Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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Article

15 pages, 4994 KiB  
Article
A Continuous Conical-Mill Operation for Dry Coating of Pharmaceutical Powders: The Role of Processing Time
by William Roy, Inès Esma Achouri, Sophie Hudon, Jean-Sébastien Simard and Nicolas Abatzoglou
Processes 2022, 10(3), 540; https://doi.org/10.3390/pr10030540 - 9 Mar 2022
Cited by 1 | Viewed by 1955
Abstract
Over the last decade, the conical mill has emerged as a potential piece of equipment to use for continuous dry coating pharmaceutical powders. In this work, silicon dioxide was used as a guest particle on two excipients, fast flow lactose (FFL) and grade [...] Read more.
Over the last decade, the conical mill has emerged as a potential piece of equipment to use for continuous dry coating pharmaceutical powders. In this work, silicon dioxide was used as a guest particle on two excipients, fast flow lactose (FFL) and grade PH200 microcrystalline cellulose (MCC), for dry coating by a conical mill with a modified screen that permitted batch and continuous mode operation. Samples were pre-processed in a V-blender. SEM images, particle size distribution, and EDS mapping were used to characterise the treated powders. Pre-processed samples showed some discrete coating of the host particle. After batch processing, the samples were covered with a complete coating. When processed at high impeller speed, coating of FFL was a mix of A200P and FFL fines generated by attrition. Continuous mode processed samples, which had a lower processing time, were coated discretely and showed a better coating than the pre-processed samples. Increasing guest/host mass ratio with FFL host particle had a positive impact on the quality of the coating. These results help to build the case that the processing time of the conical mill is a key parameter to the success of the conical mill as dry coating equipment in the pharmaceutical industry. Full article
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12 pages, 1078 KiB  
Article
Insights into the Impact of Rosmarinic Acid on CHO Cell Culture Improvement through Transcriptomics Analysis
by Zhuangrong Huang, Jianlin Xu, Jun Tian, Kathryn L. Aron, Yueming Qian, Michael C. Borys, Zhengjian Li and Girish Pendse
Processes 2022, 10(3), 533; https://doi.org/10.3390/pr10030533 - 8 Mar 2022
Cited by 1 | Viewed by 2867
Abstract
The use of antioxidants in Chinese hamster ovary (CHO) cell cultures to improve monoclonal antibody production has been a topic of great interest. Nevertheless, the antioxidants do not have consistent benefits of production improvement, which might be cell line specific and/or process specific. [...] Read more.
The use of antioxidants in Chinese hamster ovary (CHO) cell cultures to improve monoclonal antibody production has been a topic of great interest. Nevertheless, the antioxidants do not have consistent benefits of production improvement, which might be cell line specific and/or process specific. In this work, we investigated how treatment with the antioxidant rosmarinic acid (RA) improved cell growth and titer in CHO cell cultures using transcriptomics. In particular, transcriptomics analysis indicated that RA treatment modified gene expression and strongly affected the MAPK and PI3K/Akt signaling pathways, which regulate cell survival and cell death. Moreover, it was observed that these signaling pathways, which had been identified to be up-regulated on day 2 and day 6 by RA, were also up-regulated over time (from initial growth phase day 2 to slow growth or protein production phase day 6) in both conditions. In summary, this transcriptomics analysis provides insights into the role of the antioxidant RA in industrial cell culture processes. The current study also represents an example in the industry of how omics can be applied to gain an in-depth understanding of CHO cell biology and to identify critical pathways that can contribute to cell culture process improvement and cell line engineering. Full article
(This article belongs to the Section Biological Processes and Systems)
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49 pages, 8161 KiB  
Article
Modeling and Optimization of Heavy Metals Biosorption by Low-Cost Sorbents Using Response Surface Methodology
by Daniela Ionela Fertu, Laura Bulgariu and Maria Gavrilescu
Processes 2022, 10(3), 523; https://doi.org/10.3390/pr10030523 - 6 Mar 2022
Cited by 17 | Viewed by 2755
Abstract
This paper exploits, through modeling and optimization, the experimental laboratory data on the biosorption of heavy metal ions Pb(II), Cd(II), and Zn(II) from aqueous media using soybean and soybean waste biomasses. The biosorption modeling was performed using the Response Surface Methodology, followed by [...] Read more.
This paper exploits, through modeling and optimization, the experimental laboratory data on the biosorption of heavy metal ions Pb(II), Cd(II), and Zn(II) from aqueous media using soybean and soybean waste biomasses. The biosorption modeling was performed using the Response Surface Methodology, followed by optimization based on numerical methods. The aim of the modeling was to establish the most probable mathematical relationship between the dependent variables (the biosorption efficiency of the biosorbents when adsorbing metal ions, R(%), and the biosorption capacity of sorbents, q(mg/g)) and the process parameters (pH; sorbent dose, DS (g/L); initial metal ion concentration in solution, c0 (mg/L); contact time, tc (min); temperature, T (°C)), validated by methodologies specific to the multiple regression analysis. Afterward, sets of solutions were obtained through optimization that correlate various values of the process parameters to maximize the objective function. These solutions also confirmed the performance of soybean waste biomass in the removal of heavy metal ions from polluted aqueous effluents. The results were validated experimentally. Full article
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20 pages, 2671 KiB  
Article
Proof-of-Concept of Continuous Transfection for Adeno-Associated Virus Production in Microcarrier-Based Culture
by Brian Ladd, Kevin Bowes, Mats Lundgren, Torbjörn Gräslund and Veronique Chotteau
Processes 2022, 10(3), 515; https://doi.org/10.3390/pr10030515 - 4 Mar 2022
Cited by 3 | Viewed by 4598
Abstract
Adeno-associated virus vectors (AAV) are reported to have a great potential for gene therapy, however, a major bottleneck for this kind of therapy is the limitation of production capacity. Higher specific AAV vector yield is often reported for adherent cell systems compared to [...] Read more.
Adeno-associated virus vectors (AAV) are reported to have a great potential for gene therapy, however, a major bottleneck for this kind of therapy is the limitation of production capacity. Higher specific AAV vector yield is often reported for adherent cell systems compared to cells in suspension, and a microcarrier-based culture is well established for the culture of anchored cells on a larger scale. The purpose of the present study was to explore how microcarrier cultures could provide a solution for the production of AAV vectors based on the triple plasmid transfection of HEK293T cells in a stirred tank bioreactor. In the present study, cells were grown and expanded in suspension, offering the ease of this type of operation, and were then anchored on microcarriers in order to proceed with transfection of the plasmids for transient AAV vector production. This process was developed in view of a bioreactor application in a 200 mL stirred-tank vessel where shear stress aspects were studied. Furthermore, amenability to a continuous process was studied. The present investigation provided a proof-of-concept of a continuous process based on microcarriers in a stirred-tank bioreactor. Full article
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12 pages, 1738 KiB  
Article
Decrease in Ca2+ Concentration in Quail Cardiomyocytes Is Faster than That in Rat Cardiomyocytes
by Yuhei Ogura, Hiroaki Ito, Shukei Sugita, Masanori Nakamura and Yoshihiro Ujihara
Processes 2022, 10(3), 508; https://doi.org/10.3390/pr10030508 - 3 Mar 2022
Cited by 2 | Viewed by 1961
Abstract
Mammals and birds have quicker heart rates compared to other species. Mammalian cardiomyocytes have T-tubule membranes that facilitate rapid changes in Ca2+ concentrations. In contrast, bird cardiomyocytes do not possess T-tubule membranes, which raises the question of how birds achieve fast heartbeats. [...] Read more.
Mammals and birds have quicker heart rates compared to other species. Mammalian cardiomyocytes have T-tubule membranes that facilitate rapid changes in Ca2+ concentrations. In contrast, bird cardiomyocytes do not possess T-tubule membranes, which raises the question of how birds achieve fast heartbeats. In this study, we compared the changes in Ca2+ concentration in cardiomyocytes isolated from adult quails and rats to elucidate the mechanism resulting in rapid heart rates in birds. Cardiomyocytes isolated from quails were significantly narrower than those isolated from rats. When Ca2+ concentration changes in the entire cardiomyocytes were measured using Fura-2 acetoxymethyl ester (AM), the time to peak was statistically longer in quails than in rats. In contrast, the decay time was markedly shorter in quails than in rats. As a result, the total time of Ca2+ concentration change was shorter in quails than in rats. A spatiotemporal analysis of Ca2+ concentration changes in quail cardiomyocytes showed that the decrease in Ca2+ concentration was faster in the center of the cell than near the cell membrane. These results suggest that avian cardiomyocytes achieve rapid changes in Ca2+ concentration by increasing the Ca2+ removal capacity in the central part of the cell compared to mammalian cardiomyocytes. Full article
(This article belongs to the Section Manufacturing Processes and Systems)
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19 pages, 2305 KiB  
Article
Modulation of Volatile Thiol Release during Fermentation of Red Musts by Wine Yeast
by Antonio G. Cordente, Christopher D. Curtin, Mark Solomon, Allie C. Kulcsar, Flynn Watson, Lisa Pisaniello, Simon A. Schmidt and Damian Espinase Nandorfy
Processes 2022, 10(3), 502; https://doi.org/10.3390/pr10030502 - 2 Mar 2022
Cited by 5 | Viewed by 3272
Abstract
During the alcoholic fermentation of grape sugars, wine yeast produces a range of secondary metabolites that play a critical role in the aroma profile of wines. One of the most impactful yeast-modified compound families, particularly in white wines, are the ‘fruity’ polyfunctional thiols, [...] Read more.
During the alcoholic fermentation of grape sugars, wine yeast produces a range of secondary metabolites that play a critical role in the aroma profile of wines. One of the most impactful yeast-modified compound families, particularly in white wines, are the ‘fruity’ polyfunctional thiols, which include 3-mercaptohexan-1-ol (3-MH) and 4-mercapto-4-methylpentan-2-one (4-MMP). While the formation and stylistic contribution of these thiols have been extensively researched in white wines, little is known about the conditions leading to their formation in red wines. In this study, we explored the ability of yeast strains to modulate the release of these aroma compounds during the fermentation of two red musts. In laboratory-scale Pinot Noir fermentations, the formation of 3-MH strongly correlated with yeast β-lyase activity, particularly with the presence of certain genotypes of the flavour-releasing gene IRC7. Subsequent production of Grenache wine at the pilot scale, with detailed compositional and sensory analysis, was undertaken to confirm laboratory-scale observations. A commercial wine strain used for expressing ‘fruity’ thiols in Sauvignon Blanc was shown to produce wines that exhibited more intense red fruit aromas. These results reveal an opportunity for winemakers to shape red wine aroma and flavour by using yeasts that might typically be considered for white wine production. Full article
(This article belongs to the Special Issue Role of Yeast in Wine Fermentation Processes)
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10 pages, 2563 KiB  
Article
Study of the Factors Limiting the Efficiency of Vertical-Type Nitride- and AlInGaP-Based Quantum-Well Micro-LEDs
by Cheng-Han Ho, Shih-Min Chen and Yuh-Renn Wu
Processes 2022, 10(3), 489; https://doi.org/10.3390/pr10030489 - 28 Feb 2022
Cited by 4 | Viewed by 3255
Abstract
The efficiency of micro-light-emitting diodes (μ-LEDs) depends enormously on the chip size, and this is connected to sidewall-trap-assisted nonradiative recombination. It is known that the internal quantum efficiency (IQE) of aluminum gallium indium phosphide (AlGaInP)-based red μ-LEDs is much lower [...] Read more.
The efficiency of micro-light-emitting diodes (μ-LEDs) depends enormously on the chip size, and this is connected to sidewall-trap-assisted nonradiative recombination. It is known that the internal quantum efficiency (IQE) of aluminum gallium indium phosphide (AlGaInP)-based red μ-LEDs is much lower than that of nitride-based μ-LEDs. To establish the major reasons giving rise to this huge IQE discrepancy, we examined the limiting factors in the two structures. For the nitride-based InGaN quantum wells, the influences of random alloy fluctuations were examined. A two-dimensional Poisson and drift-diffusion solver was applied to analyze these issues. Full article
(This article belongs to the Section Materials Processes)
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11 pages, 2236 KiB  
Article
Potential Use of Microbial Fuel Cell Technology in Wastewater Treatment
by Ralitza Koleva, Gergana Peeva, Hyuseyin Yemendzhiev and Valentin Nenov
Processes 2022, 10(3), 486; https://doi.org/10.3390/pr10030486 - 28 Feb 2022
Cited by 3 | Viewed by 2594
Abstract
Two options, in regard to applying microbial fuel cells (MFCs) in water treatment, are under discussion, namely the conversion of the chemical energy of organic substrates to electricity, as well as the use their potential to reduce different species, such as the ionic [...] Read more.
Two options, in regard to applying microbial fuel cells (MFCs) in water treatment, are under discussion, namely the conversion of the chemical energy of organic substrates to electricity, as well as the use their potential to reduce different species, such as the ionic form of copper (Cu2+ converted to metal copper) and iron (Fe3+ converted to Fe2+). The high reduction potential of Cu2+ and Fe3+ makes the processes of electricity production and metal reduction, to be performed simultaneously in MFC, achievable. The electrical yield measurement during the experiments of anodic organic matter degradation by MFC in treating an artificial wastewater with chemical oxygen demand (COD) 0.6 and 1.6 g O2·dm−3, as initial COD, are given. It is demonstrated that the higher organic load is associated with better electrical yield. A comparison of MFC and conventional anaerobic digestion performance is discussed, as well. Experimental proofs of copper removal and phosphate mobilization, following the iron reduction of FePO4, are also reported. Full article
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17 pages, 3456 KiB  
Article
Climate Neutrality Concepts for the German Chemical–Pharmaceutical Industry
by Axel Schmidt, Dirk Köster and Jochen Strube
Processes 2022, 10(3), 467; https://doi.org/10.3390/pr10030467 - 25 Feb 2022
Cited by 6 | Viewed by 2621
Abstract
This paper intends to propose options for climate neutrality concepts by taking non-German international experiences and decisions made into account. Asia-Pacific and Arabic countries do have already same lessons learned by large-scale projects with regard to economic evaluations. Quite a few conceptual studies [...] Read more.
This paper intends to propose options for climate neutrality concepts by taking non-German international experiences and decisions made into account. Asia-Pacific and Arabic countries do have already same lessons learned by large-scale projects with regard to economic evaluations. Quite a few conceptual studies to generate the climate neutrality of the chemical–pharmaceutical industry in Germany have been published recently. Most of the studies differ even in magnitude but do not refer to or evaluate the other ones. These are all first theoretical feasibility studies. Experimental piloting is not far developed; only few and only stand-alone parts are operated, with no overall concepts. Economic evaluation is missing nearly completely. Economic analysis shows a factor 3 more expensive green technologies. Even if a large optimization potential of about 30% during manufacturing optimization is assumed as significant, cost increases would result. To make green products nevertheless competitive, the approach is to increase the carbon-source cost analogue, e.g., by CO2/ton taxes by around EUR 100, which would lead to about factor 3 higher consumer prices regarding the material amount. Furthermore, some countries would not participate in such increases and would have benefits on the world market. Whether any customs-duties policy could balance that is generally under question. Such increasing costs are not imaginable for any social-political system. Therefore, the only chance to realize consequent climate neutrality is to speed up research on more efficient and economic technologies, including, e.g., reaction intensification technologies such as plasma ionization, catalyst optimization, section coupling to cement, steel and waste combustion branches as well as pinch technology integration and appropriate scheduling. In addition, digital twins and process analytical technologies for consequent process automation would help to decrease costs. All those technologies seem to lead to even less personnel, but who need to be highly educated to deal with complex integrated systems. Research and education/training has to be designed for those scenarios. Germany as a resource-poor country could benefit from its human resources. Germany is and will be an energy importing country. Full article
(This article belongs to the Special Issue Towards Autonomous Operation of Biologics and Botanicals)
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14 pages, 9949 KiB  
Article
Faba Bean Fractions for 3D Printing of Protein-, Starch- and Fibre-Rich Foods
by Mathias Johansson, Klara Nilsson, Fanny Knab and Maud Langton
Processes 2022, 10(3), 466; https://doi.org/10.3390/pr10030466 - 25 Feb 2022
Cited by 13 | Viewed by 3443
Abstract
Food 3D printing allows for the production of personalised foods in terms of shape and nutrition. In this study, we examined whether protein-, starch- and fibre-rich fractions extracted from faba beans can be combined to produce fibre- and protein-rich printable food inks for [...] Read more.
Food 3D printing allows for the production of personalised foods in terms of shape and nutrition. In this study, we examined whether protein-, starch- and fibre-rich fractions extracted from faba beans can be combined to produce fibre- and protein-rich printable food inks for extrusion-based 3D printing. Small amplitude oscillatory shear measurements were used to characterise the inks while compression tests and scanning electron microscopy were used to characterise the freeze-dried samples. We found that rheological parameters such as storage modulus, loss tangent and yield stress were related to ink printability and shape stability. Investigations on the effect of ink composition, infill pattern (honeycomb/grid) and direction of compression on textural and microstructural properties of freeze-dried 3D-printed objects revealed no clear effect of infill pattern, but a strong effect of direction of compression. Microstructure heterogeneity seemed to be correlated with the textural properties of the printed objects. Full article
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23 pages, 1245 KiB  
Article
Optimal Darwinian Selection of Microorganisms with Internal Storage
by Walid Djema, Térence Bayen and Olivier Bernard
Processes 2022, 10(3), 461; https://doi.org/10.3390/pr10030461 - 24 Feb 2022
Cited by 6 | Viewed by 1249
Abstract
In this paper, we investigate the problem of species separation in minimal time. Droop model is considered to describe the evolution of two distinct populations of microorganisms that are in competition for the same resource in a photobioreactor. We focus on an optimal [...] Read more.
In this paper, we investigate the problem of species separation in minimal time. Droop model is considered to describe the evolution of two distinct populations of microorganisms that are in competition for the same resource in a photobioreactor. We focus on an optimal control problem (OCP) subject to a five-dimensional controlled system in which the control represents the dilution rate of the chemostat. The objective is to select the desired species in minimal-time and to synthesize an optimal feedback control. This is a very challenging issue, since we are are dealing with a ten-dimensional optimality system. We provide properties of optimal controls allowing the strain of interest to dominate the population. Our analysis is based on the Pontryagin Maximum Principle (PMP), along with a thorough study of singular arcs that is crucial in the synthesis of optimal controls. These theoretical results are also extensively illustrated and validated using a direct method in optimal control (via the Bocop software for numerically solving optimal control problems). The approach is illustrated with numerical examples with microalgae, reflecting the complexity of the optimal control structure and the richness of the dynamical behavior. Full article
(This article belongs to the Special Issue Mathematical Modeling and Control of Bioprocesses)
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21 pages, 4261 KiB  
Article
Purposely Development of the Adaptive Potential of Activated Sludge from Municipal Wastewater Treatment Plant Focused on the Treatment of Landfill Leachate
by Mihaela Belouhova, Ivaylo Yotinov, Irina Schneider, Nora Dinova, Yovana Todorova, Valentina Lyubomirova, Veronika Mihaylova, Elmira Daskalova, Stilyana Lincheva and Yana Topalova
Processes 2022, 10(3), 460; https://doi.org/10.3390/pr10030460 - 24 Feb 2022
Cited by 4 | Viewed by 2376
Abstract
Biological treatment is a key technology in landfill leachate treatment However, often its efficiency is not high enough due to the pollutants in concentrations above the critical ones. The present study aimed to investigate the adaptive responses that occur in activated sludge (AS) [...] Read more.
Biological treatment is a key technology in landfill leachate treatment However, often its efficiency is not high enough due to the pollutants in concentrations above the critical ones. The present study aimed to investigate the adaptive responses that occur in activated sludge (AS) during landfill leachate purification. A model process with AS from a municipal wastewater treatment plant and landfill leachate in increasing concentrations was constructed. The data showed that when dilutions 25 and 50 times had been applied the structure of the AS was preserved, but the COD cannot be reduced below 209 mg O2/L. The feed of undiluted leachate destroyed the AS structure as SVI was reduced to 1 mL/g, biotic index to 1, floc size was greatly reduced and COD remained high (2526 mg O2/L). The dominant group of protozoa was changed from attached to free-swimming ciliates. An increase of the bacterial groups responsible for the xenobiotics elimination (aerobic heterotrophs, genera Pseudomonas, Acinetobacter, Azoarcus, Thauera, Alcaligenes) was registered. This was accompanied by a significant increase in free bacteria. The obtained data showed that for optimal treatment of this type of water it is necessary to include a combination of biological treatment with another non-biological method (membrane filtration, reverse osmosis, etc.). Full article
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12 pages, 2298 KiB  
Article
Investigating the Trade-Off between Design and Operational Flexibility in Continuous Manufacturing of Pharmaceutical Tablets: A Case Study of the Fluid Bed Dryer
by Sheng-Long Jiang, Lazaros G. Papageorgiou, Ian David L. Bogle and Vassilis M. Charitopoulos
Processes 2022, 10(3), 454; https://doi.org/10.3390/pr10030454 - 24 Feb 2022
Cited by 3 | Viewed by 2014
Abstract
Market globalisation, shortened patent lifetimes and the ongoing shift towards personalised medicines exert unprecedented pressure on the pharmaceutical industry. In the push for continuous pharmaceutical manufacturing, processes need to be shown to be agile and robust enough to handle variations with respect to [...] Read more.
Market globalisation, shortened patent lifetimes and the ongoing shift towards personalised medicines exert unprecedented pressure on the pharmaceutical industry. In the push for continuous pharmaceutical manufacturing, processes need to be shown to be agile and robust enough to handle variations with respect to product demands and operating conditions. In this paper we examine the use of operational envelopes to study the trade-off between the design and operational flexibility of the fluid bed dryer at the heart of a tablet manufacturing process. The operating flexibility of this unit is key to the flexibility of the full process and its supply chain. The methodology shows that for the fluid bed dryer case study there is significant effect on flexibility of the process at different drying times with the optimal obtained at 700 s. The flexibility is not affected by the change in volumetric flowrate, but only by the change in temperature. Here the method used a black box model to show how it could be done without access to the full model equation set, as this often needs to be the case in commercial settings. Full article
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12 pages, 4045 KiB  
Article
Comparative Metagenomics of Anaerobic Digester Communities Reveals Sulfidogenic and Methanogenic Microbial Subgroups in Conventional and Plug Flow Residential Septic Tank Systems
by James Naphtali, Alexander W. Y. Chan, Faizan Saleem, Enze Li, Jacob Devries and Herb E. Schellhorn
Processes 2022, 10(3), 436; https://doi.org/10.3390/pr10030436 - 22 Feb 2022
Cited by 5 | Viewed by 2507
Abstract
On-site wastewater treatment systems (OWTS) are primarily monitored using physiochemical factors, including chemical oxygen demand (COD) and residual total suspended solids (TSS), which are indirect measures of the microbial action during the anaerobic digestion process. Changes in anaerobic digester microbial communities can alter [...] Read more.
On-site wastewater treatment systems (OWTS) are primarily monitored using physiochemical factors, including chemical oxygen demand (COD) and residual total suspended solids (TSS), which are indirect measures of the microbial action during the anaerobic digestion process. Changes in anaerobic digester microbial communities can alter the digester performance, but this information cannot be directly obtained from traditional physicochemical indicators. The potential of metagenomic DNA sequencing as a tool for taxonomic and functional profiling of microbial communities was examined in both common conventional and plug flow-type anaerobic digesters (single-pass and recirculating). Compared to conventional digesters, plug flow-type digesters had higher relative levels of sulfate-reducing bacteria (Desulfovibrio spp.) and hydrogenotrophic methanogens (Methanospirillum spp.). In contrast, recirculating anaerobic digesters were enriched with denitrifier bacteria and hydrogenotrophic methanogens, and both were significantly correlated with physicochemical factors such as COD and TSS. Stratification of microbial communities was observed along the digester treatment process according to hydrolytic, acidogenic, acetogenic, and methanogenic subgroups. These results indicate that the high-throughput DNA sequencing may be useful as a monitoring tool to characterize the changes in bacterial communities and the functional profile due to differences in digester design in on-site systems. Full article
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12 pages, 2851 KiB  
Article
Effects of Biochar Application on Vegetation Growth, Cover, and Erosion Potential in Sloped Cultivated Soil Derived from Mudstone
by Ming-Hsi Lee, Huan-Hsuan Lin and Shih-Hao Jien
Processes 2022, 10(2), 306; https://doi.org/10.3390/pr10020306 - 4 Feb 2022
Cited by 3 | Viewed by 1823
Abstract
Soil degradation is a crucial problem, particularly in tropical and subtropical areas. Prevention or reduction of soil erosion requires strategies based on thorough rapid vegetation cover (VC) and favorable soil quality in subtropical and tropical areas. This study applied wood biochar (WB) and [...] Read more.
Soil degradation is a crucial problem, particularly in tropical and subtropical areas. Prevention or reduction of soil erosion requires strategies based on thorough rapid vegetation cover (VC) and favorable soil quality in subtropical and tropical areas. This study applied wood biochar (WB) and rice husk biochar (RHB) in a mudstone soil, which is widely distributed in Southern Taiwan, to investigate the effects of biochar application on soil erosion and vegetation restoration. The standard erosion unit plots (22.13 m in length and 9% in slope gradient) were set up to determine the relationship among soil losses, VC, and natural rainfall characteristics with and without biochar application. The results indicated that biochar application increased the growth rate (identified by cover ratio) of Bahia grass (Paspalum notatum Flüggé) by 2–2.6 times within 40 days compared with control (without biochar application) and increased VC by 20% after 120 days of treatment. The biochar application could effectively reduce soil losses by 60% at least in the mudstone soil. A well-predicted regression function of soil loss with VC and rainfall kinetic energy was established (amount of soil lost = −0.435 × ln VC + 0.54 × RKE, r = 0.89, p < 0.01). Full article
(This article belongs to the Section Environmental and Green Processes)
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10 pages, 622 KiB  
Article
Bulk Process for Enrichment of Capsinoids from Capsicum Fruit
by Charles L. Cantrell and Robert L. Jarret
Processes 2022, 10(2), 305; https://doi.org/10.3390/pr10020305 - 4 Feb 2022
Cited by 3 | Viewed by 1890
Abstract
Various methods to synthesize capsinoids (the nonpungent analogs of capsaicinoids) from precursor molecules have been reported. Capsinoids are also naturally present, at typically low concentrations, in the fruit of many Capsicum species and genotypes. However, they are also present in the fruit of [...] Read more.
Various methods to synthesize capsinoids (the nonpungent analogs of capsaicinoids) from precursor molecules have been reported. Capsinoids are also naturally present, at typically low concentrations, in the fruit of many Capsicum species and genotypes. However, they are also present in the fruit of select genotypes at high concentrations. The fruit of high-capsiate genotypes represents a commercial source of these compounds. To date, no method has been published that efficiently extracts and purifies capsinoids from Capsicum fruit in a rapid and simple bulk process. This study evaluated the efficacy of various organic solvents for the extraction of capsinoids from dried Capsicum annuum fruit. Among the organic solvents evaluated, pentane appeared to provide a good combination of both recovery and purity. A subsequent liquid/liquid extraction step, utilizing pentane and acetonitrile, resulted in 26.3% (wt/wt) capsiate and 19.4% (wt/wt) dihydrocapsiate for a combined capsinoids yield of 45.7% (wt/wt). A third step, involving a rapid hp20ss chromatography column using a water/acetonitrile gradient, resulted in a combined capsinoids yield of 96.6% (wt/wt). Full article
(This article belongs to the Section Biological Processes and Systems)
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18 pages, 3838 KiB  
Article
Manno-Oligosaccharide Production from Biomass Hydrolysis by Using Endo-1,4-β-Mannanase (ManNj6-379) from Nonomuraea jabiensis ID06-379
by Shanti Ratnakomala, Prihardi Kahar, Norimasa Kashiwagi, JaeMin Lee, Motonori Kudou, Hana Matsumoto, Pamella Apriliana, Yopi Yopi, Bambang Prasetya, Chiaki Ogino and Akihiko Kondo
Processes 2022, 10(2), 269; https://doi.org/10.3390/pr10020269 - 29 Jan 2022
Cited by 3 | Viewed by 2837
Abstract
A novel endo-β-1,4-mannanase gene was cloned from a novel actinomycetes, Nonomuraea jabiensis ID06-379, isolated from soil, overexpressed as an extracellular protein (47.8 kDa) in Streptomyces lividans 1326. This new endo-1,4-β-mannanase gene (manNj6-379) is encoded by 445-amino acids. The ManNj6-379 consists of [...] Read more.
A novel endo-β-1,4-mannanase gene was cloned from a novel actinomycetes, Nonomuraea jabiensis ID06-379, isolated from soil, overexpressed as an extracellular protein (47.8 kDa) in Streptomyces lividans 1326. This new endo-1,4-β-mannanase gene (manNj6-379) is encoded by 445-amino acids. The ManNj6-379 consists of a 28-residue signal peptide and a carbohydrate-binding module of family 2 belonging to the glycoside hydrolase (GH) family 5, with 59–77% identity to GH5 mannan endo-1,4-β-mannanase. The recombinant ManNj6-379 displayed an optimal pH of 6.5 with pH stability ranging between 5.5 and 7.0 and was stable for 120 min at 50 °C and lower temperatures. The optimal temperature for activity was 70 °C. An enzymatic hydrolysis assay revealed that ManNj6-379 could hydrolyze commercial β-mannan and biomass containing mannan. Full article
(This article belongs to the Section Biological Processes and Systems)
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8 pages, 1214 KiB  
Communication
Functional Compounds from Banana Peel Used to Decrease Oxidative Stress Effects
by Ionela Avram, Florentina Gatea and Emanuel Vamanu
Processes 2022, 10(2), 248; https://doi.org/10.3390/pr10020248 - 27 Jan 2022
Cited by 6 | Viewed by 6452
Abstract
Banana peel, a little-used waste, contains a high amount of biologically active compounds. The aim of the study is to demonstrate in vitro, the antioxidant, cytotoxic, and antimicrobial effects of hydroalcoholic extracts from yellow (BP) and red (BPR) banana peels. The analysis [...] Read more.
Banana peel, a little-used waste, contains a high amount of biologically active compounds. The aim of the study is to demonstrate in vitro, the antioxidant, cytotoxic, and antimicrobial effects of hydroalcoholic extracts from yellow (BP) and red (BPR) banana peels. The analysis of the extracts by Capillary Zone Electrophoresis (CZE) has confirmed the presence of several bioactive compounds. BPR has a higher in vitro antioxidant activity than BP, which correlates with a significant cytotoxic, antimicrobial effect, with a UVA/UVB rate of 0.9. In the case of BPR, the results confirm the presence of isoquercitrin and kaempferol in a 1:3 ratio. The bioactive compounds from the extracts have shown a different interaction with HCT-8 cell lines and with tested bacterial strains with pathogenic properties. The HCA analysis proved the biological value of BPR to reduce oxidative stress and its potential use in natural products. Full article
(This article belongs to the Special Issue Bioactive Compounds from Food Waste and By-Products)
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12 pages, 1574 KiB  
Article
Applicability of Food Grade Modified Starches as a Carrier of Microelements
by Hanna Śmigielska, Wioletta Błaszczak and Grażyna Lewandowicz
Processes 2022, 10(2), 235; https://doi.org/10.3390/pr10020235 - 26 Jan 2022
Cited by 3 | Viewed by 2720
Abstract
Growth in the human population and intensive, large-scale farming results in a lowering in the quality of nutrition. An oversupply of food energy is often accompanied with a deficiency in micronutrients. To address this problem, the food industry provides products enriched with bioactive [...] Read more.
Growth in the human population and intensive, large-scale farming results in a lowering in the quality of nutrition. An oversupply of food energy is often accompanied with a deficiency in micronutrients. To address this problem, the food industry provides products enriched with bioactive substances. The main challenge of this technology is the even distribution of micronutrients in the matrix of the fortified food. A possible solution to this challenge is to use stable and effective carriers. The aim of this work was to verify the applicability of native potato starch and modified starches (commonly used in the food industry) as carriers for microelements. Adsorptions were carried out in starch suspensions at a temperature below gelatinisation. The native potato starch and the modified starches (E 1404, E 1412, E 1420, and E 1422) were assessed for their effectiveness in adsorbing copper, iron, and zinc sulphates or gluconates. Pasting characteristics were analysed using a Brabender viscograph and light microscopy. Furthermore, texture profile analysis of starch-based desserts was carried out with the use of the tested carriers. Starch in both its native and modified forms was able to effectively adsorb copper, iron, and zinc ions. Adsorption was more efficient when using modified starches containing hydrophilic carboxyl groups. The effectiveness of adsorption with oxidised starches increased with an increase in the degree of substitution. Starches containing more hydrophobic acetyl groups were less effective as adsorbents of microelements. The cation adsorption efficiency decreased in the order copper > iron > zinc, and sulphates were better adsorbed than gluconates. Copper ions influenced the pasting characteristics of the oxidised starches, and these effects were dependent on the degree of substitution with carboxyl groups. As observed by light microscopy, the presence of copper ions changes the interaction between the starch macromolecules and water. However, the above-mentioned changes did not significantly affect the texture of traditional sweet desserts. Starch, particularly its oxidised derivatives containing hydrophilic oxidised groups, can be recommended as a carrier of microelements for food fortification. The use of modified starches containing relatively hydrophobic acetyl groups is not appropriate because they absorb microelements less efficiently than native starch. Full article
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13 pages, 864 KiB  
Article
Valorising Agricultural Residues through Pelletisation
by Daniele Duca, Vittorio Maceratesi, Sara Fabrizi and Giuseppe Toscano
Processes 2022, 10(2), 232; https://doi.org/10.3390/pr10020232 - 26 Jan 2022
Cited by 5 | Viewed by 2496
Abstract
The agricultural sector and its related production chains are good sources of residual biomass. Olive and vineyard pruning residues are present in high quantities in Italy. The limited bulk and energy densities of these biomass materials affect the harvesting and logistic costs, limiting [...] Read more.
The agricultural sector and its related production chains are good sources of residual biomass. Olive and vineyard pruning residues are present in high quantities in Italy. The limited bulk and energy densities of these biomass materials affect the harvesting and logistic costs, limiting energy and environmental sustainability. Pelletisation is the most efficient process for increasing bulk and energy densities. This study evaluates the pelletisation process of olive and vineyard prunings, pure, or blended with variable quantities of spruce sawdust. A 15 kW pelletisation system was chosen, in line with production at the farm level. The most important quality parameters of the produced agripellets were analyzed. The results of this investigation suggest that blending could valorize other biomass materials less suitable for pelletisation and reach the pellet quality required by Italian technical standards. The addition of pruning residues to spruce sawdust leads to an improvement in durability. Spruce sawdust pellets have a durability value of 78.4%. Adding 20% of olive prunings (S80O20) increases this value to 92.2, while adding 20% vineyard prunings (S80V20) increases this value up to 90.3. The addition of 20% of pruning residues significantly increased the length and decreased fines. Full article
(This article belongs to the Special Issue Biomass Conversion Process and Biorefinery)
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13 pages, 800 KiB  
Article
Beetroot By-Product as a Functional Ingredient for Obtaining Value-Added Mayonnaise
by Silvia Lazăr (Mistrianu), Oana Emilia Constantin, Georgiana Horincar, Doina Georgeta Andronoiu, Nicoleta Stănciuc, Claudia Muresan and Gabriela Râpeanu
Processes 2022, 10(2), 227; https://doi.org/10.3390/pr10020227 - 25 Jan 2022
Cited by 11 | Viewed by 4599
Abstract
Beetroot peel is a by-product obtained during the processing of beetroots and is an essential source of bioactive substances beneficial to health. This study used antioxidant-rich beetroot peels powder (BPP) in different concentrations (1.5, 3, 5, and 7%) to obtain value-added mayonnaise. The [...] Read more.
Beetroot peel is a by-product obtained during the processing of beetroots and is an essential source of bioactive substances beneficial to health. This study used antioxidant-rich beetroot peels powder (BPP) in different concentrations (1.5, 3, 5, and 7%) to obtain value-added mayonnaise. The impact of BPP on the phytochemical composition, sensory characteristics, viscosity, color, and textural properties of the mayonnaises were also investigated. The BPP was characterized by a high betalain content (1.18 ± 0.03 mg/g DW) and rich polyphenolic content (225.36 ± 1.97 mg GAE/g DW) and showed high antioxidant activity. The purple-red colored powders added to the mayonnaise allowed a significant increase in total phenolic content and the antioxidant activity of purple-red colored powders added to the mayonnaise. The total color difference ΔE value in the mayonnaise samples increased with extract concentration. The instrumental texture analysis findings revealed that BPP addition to the mayonnaise increased the firmness, adhesiveness, and cohesiveness and improved the samples’ chewiness. The viscosity of mayonnaise was also significantly improved. The inclusion of BPP improved the color, according to sensory evaluation and overall acceptability of the mayonnaise formulation. The results give a novel formulation and technological insights into the influence of BPP-powder enrichment on the physical, sensory, and textural qualities of mayonnaise. BPP could be employed as a natural ingredient in several value-added emulsions, including sauces, mayonnaise, dressings, and creams. Full article
(This article belongs to the Special Issue Recent Advances in Natural Bioactive Compound Valorization)
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15 pages, 7938 KiB  
Article
Impact of Silica Additions on the Phase Composition and Electrical Transport Properties of Ruddlesden-Popper La2NiO4+δ Mixed Conducting Ceramics
by Kiryl Zakharchuk, Aleksandr Bamburov, Eugene N. Naumovich, Miguel A. Vieira and Aleksey A. Yaremchenko
Processes 2022, 10(1), 82; https://doi.org/10.3390/pr10010082 - 31 Dec 2021
Cited by 2 | Viewed by 2110
Abstract
The present work explores the possibility of incorporation of silicon into the crystal structure of Ruddlesden-Popper La2NiO4+δ mixed conducting ceramics with the aim to improve the chemical compatibility with lanthanum silicate-based solid electrolytes. Ceramics with the nominal composition La2 [...] Read more.
The present work explores the possibility of incorporation of silicon into the crystal structure of Ruddlesden-Popper La2NiO4+δ mixed conducting ceramics with the aim to improve the chemical compatibility with lanthanum silicate-based solid electrolytes. Ceramics with the nominal composition La2Ni1−ySiyO4+δ (y = 0, 0.02 and 0.05) were prepared by the glycine nitrate combustion technique and sintered at 1450 °C. While minor changes in the lattice parameters of the tetragonal K2NiF4-type lattice may suggest incorporation of a small fraction of Si into the Ni sublattice, combined XRD and SEM/EDS studies indicate that this fraction is very limited (≪2 at.%, if any). Instead, additions of silica result in segregation of apatite-type La10−xSi6O26+δ and La2O3 secondary phases as confirmed experimentally and supported by the static lattice simulations. Both total electrical conductivity and oxygen-ionic transport in La2NiO4+δ ceramics are suppressed by silica additions. The preferential reactivity of silica with lanthanum oxide opens a possibility to improve the compatibility between lanthanum silicate-based solid electrolytes and La2NiO4+δ-based electrodes by appropriate surface modifications. The promising potential of this approach is supported by preliminary tests of electrodes infiltrated with lanthanum oxide. Full article
(This article belongs to the Section Energy Systems)
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21 pages, 5147 KiB  
Article
Treatment of Winery Wastewater with a Combination of Adsorption and Thermocatalytic Processes
by Nuno Jorge, Ana R. Teixeira, Vanessa Guimarães, Marco S. Lucas and José A. Peres
Processes 2022, 10(1), 75; https://doi.org/10.3390/pr10010075 - 30 Dec 2021
Cited by 17 | Viewed by 2477
Abstract
The release of winery wastewater (WW) into the environment, without proper treatment, can cause severe problems to freshwater quality and natural fauna and flora. Therefore, in this work a treatment process was studied, combining adsorption and thermocatalytic oxidation processes. In a more specific [...] Read more.
The release of winery wastewater (WW) into the environment, without proper treatment, can cause severe problems to freshwater quality and natural fauna and flora. Therefore, in this work a treatment process was studied, combining adsorption and thermocatalytic oxidation processes. In a more specific way, it optimized the combination of activated sodium bentonite (Na-Mt) and potassium persulfate (KPS)/sodium percarbonate (SPC) as oxidant agents. With the combination of best operational conditions of adsorption ([Na-Mt] = 5.0 g/L, pH = 3.0, V = 500 mL, agitation 350 rpm, T = 298 K, t = 24 h) and thermocatalytic oxidation processes (S2O82/H2O2 ratio = 1:0.25, S2O82/H2O2 dosage = 0.1:0.025 (g/g), pH = 7.0, T = 343 K, agitation 350 rpm, t = 2 h), a total organic carbon, chemical oxygen demand and total polyphenols removal of 76.7, 81.4 and >99% was achieved, respectively. Finally, it was evaluated the effect of the treatment processes in the germination index (GI) of different plant seeds. A GI > 80% was achieved, showing a low phytotoxicity effect of the processes applied in the winery wastewater treatment. Full article
(This article belongs to the Section Environmental and Green Processes)
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18 pages, 11247 KiB  
Article
Optimal Magnetic Graphite Heater Design for Impurity Control in Single-Crystal Si Grower Using Crystal Growth Simulation
by Hye Jun Jeon, Hyeonwook Park, Salh Alhammadi, Jae Hak Jung and Woo Kyoung Kim
Processes 2022, 10(1), 70; https://doi.org/10.3390/pr10010070 - 30 Dec 2021
Viewed by 2528
Abstract
In this paper, we report a successfully modified single-crystal Si growth furnace for impurity control. Four types of arbitrary magnetic heater (AMGH) systems with 3, 4, 5, and poly parts were designed in a coil shape and analyzed using crystal growth simulation. The [...] Read more.
In this paper, we report a successfully modified single-crystal Si growth furnace for impurity control. Four types of arbitrary magnetic heater (AMGH) systems with 3, 4, 5, and poly parts were designed in a coil shape and analyzed using crystal growth simulation. The concentration of oxygen impurities in single-crystal Si ingots was compared among the designed AMGHs and a normal graphite heater (NGH). The designed AMGHs were confirmed to be able to control turbulence and convection in a molten state, which created a vortex that influenced the oxygen direction near the melt–crystal interface. It was confirmed that replacing NGH with AMGHs resulted in a reduction in the average oxygen concentration at the Si melt–crystal interface by approximately 4.8%. Full article
(This article belongs to the Special Issue Design and Optimization in Process Engineering)
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21 pages, 7269 KiB  
Article
Thermal Behavior of Ceramic Bodies Based on Estonian Clay from the Arumetsa Deposit with Oil Shale Ash and Clinker Dust Additives
by Tiit Kaljuvee, Igor Štubňa, Tomáš Húlan, Mai Uibu, Marve Einard, Rainer Traksmaa, Mart Viljus, Jekaterina Jefimova and Andres Trikkel
Processes 2022, 10(1), 46; https://doi.org/10.3390/pr10010046 - 27 Dec 2021
Cited by 7 | Viewed by 2821
Abstract
The thermal behavior of green clay samples from the Arumetsa and Füzérradvány deposits (Hungary) and the influence of two new types of Estonian oil shale (OS) ashes and cement bypass dust (clinker dust) additives on it were the objectives of this study. Thermal [...] Read more.
The thermal behavior of green clay samples from the Arumetsa and Füzérradvány deposits (Hungary) and the influence of two new types of Estonian oil shale (OS) ashes and cement bypass dust (clinker dust) additives on it were the objectives of this study. Thermal and thermo-dilatometric analysis methods were applied using a Setaram Setsys 1750 thermoanalyzer coupled with a Pfeiffer Omnistar spectrometer and a Setaram Setsys 1750 CS Evolution dilatometer. The kinetic parameters were calculated based on the differential isoconversional method of Friedman. The results of the thermal analysis of clays and blends indicated the emission of physically bound water at 200–250 °C. At temperatures from 200–250 °C to 550–600 °C the release of water is caused by oxidation of organic matter and dehydroxylation of different clay minerals like illite, illite-smectite, mica and kaolin. From blends, in addition, also from the decomposition of portlandite. The emission of CO2 at these temperatures was a result of the oxidation of organic matter contained in the clays. In the temperature range from 550–600 °C to 800–900 °C, the mass loss was caused by ongoing dehydroxylation processes in clay minerals but was mainly due to the decomposition of the carbonates contained in the OS ashes and clinker dust. These processes were accompanied by contraction and expansion of the ceramic bodies with the corresponding changes in the SSA and porosity values of the samples. Therefore, the decomposition of the clays took place in one step which blends in two steps. At first, dehydroxylation of the clay minerals occurs, followed by decomposition of the carbonates. The value of the conversion-dependent activation energy E along the reaction progress α varied for the Arumetsa and illitic clay between 75–182 and 9–206 kJ mol−1, respectively. For the blends based on Arumetsa and illitic clay, the activation energy of the first step varied between 14–193 and 5–205 kJ mol−1, and for the second step, it was between 15–390 and 135–235 kJ mol−1, respectively, indicating the complex mechanism of the processes. Full article
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18 pages, 4260 KiB  
Article
A Sustainable Process to Produce Manganese and Its Alloys through Hydrogen and Aluminothermic Reduction
by Jafar Safarian
Processes 2022, 10(1), 27; https://doi.org/10.3390/pr10010027 - 24 Dec 2021
Cited by 7 | Viewed by 4444
Abstract
Hydrogen and aluminum were used to produce manganese, aluminum–manganese (AlMn) and ferromanganese (FeMn) alloys through experimental work, and mass and energy balances. Oxide pellets were made from Mn oxide and CaO powder, followed by pre-reduction by hydrogen. The reduced MnO pellets were then [...] Read more.
Hydrogen and aluminum were used to produce manganese, aluminum–manganese (AlMn) and ferromanganese (FeMn) alloys through experimental work, and mass and energy balances. Oxide pellets were made from Mn oxide and CaO powder, followed by pre-reduction by hydrogen. The reduced MnO pellets were then smelted and reduced at elevated temperatures through CaO flux and Al reductant addition, yielding metallic Mn. Changing the amount of the added Al for the aluminothermic reduction, with or without iron addition led to the production of Mn metal, AlMn alloy and FeMn alloy. Mass and energy balances were carried out for three scenarios to produce these metal products with feasible material flows. An integrated process with three main steps is introduced; a pre-reduction unit to pre-reduce Mn ore, a smelting-aluminothermic reduction unit to produce metals from the pre-reduced ore, and a gas treatment unit to do heat recovery and hydrogen looping from the pre-reduction process gas. It is shown that the process is sustainable regarding the valorization of industrial waste and the energy consumptions for Mn and its alloys production via this process are lower than current commercial processes. Ferromanganese production by this process will prevent the emission of about 1.5 t CO2/t metal. Full article
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8 pages, 2800 KiB  
Article
The Effects of the Acid Treatment of ZrB2 Particles on Their Purity and Aqueous Dispersibility
by Jinuk Choi and Gye Seok An
Processes 2022, 10(1), 18; https://doi.org/10.3390/pr10010018 - 23 Dec 2021
Cited by 2 | Viewed by 2142
Abstract
Oxide impurities such as boria (B2O3) and zirconia (ZrO2) on the surfaces of zirconium diboride (ZrB2) particles are known to limit their sinterability. Among the impurities, B2O3 on the surface of ZrB [...] Read more.
Oxide impurities such as boria (B2O3) and zirconia (ZrO2) on the surfaces of zirconium diboride (ZrB2) particles are known to limit their sinterability. Among the impurities, B2O3 on the surface of ZrB2 particles could be easily removed by methanol or hydrofluoric acid. However, the remaining ZrO2 still gave negative influences on the sinterability. In this study, ZrB2 particles were treated with various acids to remove oxide impurities on their surfaces. The acid treatments were found to vary in efficacy, according to acid type, and affect the crystallinity and morphology of ZrB2 particles to varying degrees, in some cases forming additional impurities. In particular, the change in the oxygen content of the ZrB2 particles induced by acid treatment was found to depend on the type of acid. The results of the acid treatments were compared which revealed that HNO3 treatment optimizes the purity of ZrB2 particles. In addition, the effects of acid treatment on the surface properties of ZrB2 particles were considered. In particular, the correlation between the surface properties of the acid-treated ZrB2 particles and their dispersibility in aqueous solution was investigated. Full article
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20 pages, 5105 KiB  
Article
Oscillating Combustion—Primary Measure to Reduce Nitrogen Oxide in a Grate Furnace–Experiments and Simulations
by Hans-Joachim Gehrmann, Bo Jaeger, Siegmar Wirtz, Viktor Scherer, Krasimir Aleksandrov, Manuela Hauser, Dieter Stapf, Gregor Pollmeier and Philipp Danz
Processes 2021, 9(12), 2210; https://doi.org/10.3390/pr9122210 - 8 Dec 2021
Cited by 6 | Viewed by 2481
Abstract
The emission from industries and the mobility sector is under strong legal regulations in many countries worldwide. In Germany, the amendment to the 17th BlmSchV (Federal pollution control ordinance), which has been in force for waste incineration plants since 2013, has given rise [...] Read more.
The emission from industries and the mobility sector is under strong legal regulations in many countries worldwide. In Germany, the amendment to the 17th BlmSchV (Federal pollution control ordinance), which has been in force for waste incineration plants since 2013, has given rise to a new limit for nitrogen oxides of 150 mg/m3 as the daily mean level from 2019 on. A similar focus is on biomass-fired plants. According to the MCP (medium combustion plant) guideline of the EU, as a consequence, existing plants are required to either increase their consumption of ammonia water for nitrogen oxide reduction (SNCR process) or back fit SCR catalysts as secondary measures, which is a costly procedure. This paper presents a novel two-stage process in which an oscillating supply of secondary air allows nitrogen oxides to be reduced by approx. 50% at a good burnout level, which may obviate the need for secondary measures. Besides experimental investigations in a fixed bed reactor, CFD simulations confirm a high potential for reduction of nitrogen oxides. Together with the company POLZENITH, this process is under development for scale-up in a biomass incineration plant as a next step. Full article
(This article belongs to the Special Issue Characterization of Emissions from Fuel Combustion)
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13 pages, 3365 KiB  
Article
Microwave Dielectric Properties of β-CaSiO3 Glass–Ceramics Prepared Using Two-Step Heat Treatment
by Jin-Seok Baek, Nak-Beom Jo and Eung-Soo Kim
Processes 2021, 9(12), 2180; https://doi.org/10.3390/pr9122180 - 3 Dec 2021
Cited by 5 | Viewed by 2171
Abstract
The microwave dielectric properties of β-CaSiO3 glass–ceramics are compared with those of α-CaSiO3 ceramics. β-CaSiO3 is prepared using glass–ceramics method with two-step heat treatment at 730 °C for 1–7 h and at 900 °C for 3 h, and α-CaSiO3 [...] Read more.
The microwave dielectric properties of β-CaSiO3 glass–ceramics are compared with those of α-CaSiO3 ceramics. β-CaSiO3 is prepared using glass–ceramics method with two-step heat treatment at 730 °C for 1–7 h and at 900 °C for 3 h, and α-CaSiO3 is prepared using conventional solid-state reaction and sintered at 1460–1500 °C for 3 h. With increasing holding time at 730 °C, the degree of crystallisation and Qf of the β-CaSiO3 glass–ceramics increased. The β-CaSiO3 specimens heat-treated at 730 °C for 3 h and 900 °C for 3 h exhibit the following dielectric properties: K = 6.57, TCF = −36.22 ppm/°C, and Qf = 52,400 GHz (highest) for the entire range of heat treatment conditions. The Qf difference between β-CaSiO3 and α-CaSiO3 could be explained by the bond characteristics using Rietveld refinement. FT-IR analysis shows that the Ca–O bond is the dominant factor for the Qf of CaSiO3 ceramics compared to the Si–O bond. The higher Qf of β-CaSiO3 than that of α-CaSiO3 can be attributed to the higher bond strength of Ca–O for β-CaSiO3 than that for α-CaSiO3. Full article
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16 pages, 8547 KiB  
Article
Large Eddy Simulation of Leakage Flow in a Stepped Labyrinth Seal
by Ji-Hwan Kim and Joon Ahn
Processes 2021, 9(12), 2179; https://doi.org/10.3390/pr9122179 - 2 Dec 2021
Cited by 4 | Viewed by 2206
Abstract
Large eddy simulation (LES) and Reynolds averaged Navier-Stokes simulation (RANS) of leakage flow in straight-through and stepped labyrinth seals were performed in order to compare their performances in sealing the secondary flow passage of the gas turbine based on the respective discharge coefficients. [...] Read more.
Large eddy simulation (LES) and Reynolds averaged Navier-Stokes simulation (RANS) of leakage flow in straight-through and stepped labyrinth seals were performed in order to compare their performances in sealing the secondary flow passage of the gas turbine based on the respective discharge coefficients. The results indicate a 17.8% higher leakage prevention performance for the stepped seal relative to that of the straight seal. Further, while the LES predicts an ~7% reduction in the discharge coefficient due to shaft rotation, this effect is underestimated by the RANS. Moreover, the LES correctly predicts a laminarized flow pattern in the clearance, whereas the RANS overestimates the turbulence kinetic energy. In addition, a turbulence kinetic energy spectrum analysis was performed based on the vorticity at selected points in order to identify the flow structure that has a dominant influence on the oscillation of the discharge coefficient. This analysis also enabled identification of the changes in the flow structure due to shaft rotation. Full article
(This article belongs to the Section Manufacturing Processes and Systems)
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22 pages, 11322 KiB  
Article
Electrochemical Performance of Iron-Doped Cobalt Oxide Hierarchical Nanostructure
by Deepa Guragain, Sunil Karna, Jonghyun Choi, Romakanta Bhattarai, Tej P. Poudel, Ram Krishna Gupta, Xiao Shen and Sanjay R. Mishra
Processes 2021, 9(12), 2176; https://doi.org/10.3390/pr9122176 - 2 Dec 2021
Cited by 10 | Viewed by 3095
Abstract
In this study, hydrothermally produced Fe-doped Co3O4 nanostructured particles are investigated as electrocatalysts for the water-splitting process and electrode materials for supercapacitor devices. The results of the experiments demonstrated that the surface area, specific capacitance, and electrochemical performance of Co [...] Read more.
In this study, hydrothermally produced Fe-doped Co3O4 nanostructured particles are investigated as electrocatalysts for the water-splitting process and electrode materials for supercapacitor devices. The results of the experiments demonstrated that the surface area, specific capacitance, and electrochemical performance of Co3O4 are all influenced by Fe3+ content. The FexCo3-xO4 with x = 1 sample exhibits a higher BET surface (87.45 m2/g) than that of the pristine Co3O4 (59.4 m2/g). Electrochemical measurements of the electrode carried out in 3 M KOH reveal a high specific capacitance of 153 F/g at a current density of 1 A/g for x = 0.6 and 684 F/g at a 2 mV/s scan rate for x = 1.0 samples. In terms of electrocatalytic performance, the electrode (x = 1.0) displayed a low overpotential of 266 mV (at a current density of 10 mA/cm2) along with 52 mV/dec Tafel slopes in the oxygen evolution reaction. Additionally, the overpotential of 132 mV (at a current density of 10 mA/cm2) and 109 mV with 52 mV/dec Tafel slope were obtained for x = 0.6 sample towards hydrogen evolution reaction (HER). According to electrochemical impedance spectroscopy (EIS) measurements and the density functional theory (DFT) study, the addition of Fe3+ increased the conductivity at the electrode–electrolyte interface, which substantially impacted the high activity of the iron-doped cobalt oxide. The electrochemical results revealed that the mesoporous Fe-doped Co3O4 nanostructure could be used as potential electrode material in the high-performance electrochemical capacitor and water-splitting catalysts. Full article
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10 pages, 3507 KiB  
Article
Kinetic Behavior of Fabricated CuO/ZrO2 Oxygen Carriers for Chemical Looping Oxygen Uncoupling
by Young Ku, Chia-Wei Chang, Shr-Han Shiu, Hsuan-Chih Wu and Niels Michiel Moed
Processes 2021, 9(12), 2156; https://doi.org/10.3390/pr9122156 - 29 Nov 2021
Cited by 1 | Viewed by 1192
Abstract
Chemical looping with oxygen uncoupling (CLOU) is an innovative alternative to conventional combustion. CuO/ZrO2 oxygen carriers were tested in this system for their effectiveness and resilience. Cupric oxide (CuO) was demonstrated to be a reliable oxygen carrier for oxygen-uncoupling with consistent recyclability [...] Read more.
Chemical looping with oxygen uncoupling (CLOU) is an innovative alternative to conventional combustion. CuO/ZrO2 oxygen carriers were tested in this system for their effectiveness and resilience. Cupric oxide (CuO) was demonstrated to be a reliable oxygen carrier for oxygen-uncoupling with consistent recyclability even after 50 redox cycles in a thermogravimetric analyzer (TGA). The reduction of CuO to generate Cu2O and oxygen was observed to be improved markedly for experiments operated at higher temperatures; however, the oxidation of Cu2O by air to generate CuO was hindered for experiments carried out at elevated temperatures. The reduction rate of fabricated CuO/ZrO2 particles containing 40% CuO was enhanced with increasing temperature and decreased with increasing particle size for experiments operated in a fixed bed reactor. The geometrical contraction and Avrami-Erofe’ev models were demonstrated to be appropriate for describing the reduction and oxidation of CuO/ZrO2, respectively. The activation energies for the reduction and oxidation were determined to be 250.6 kJ/mol and 57.6 kJ/mol, respectively, based on experimental results in the temperature range between 850 and 1000 °C. Full article
(This article belongs to the Special Issue Characterization of Emissions from Fuel Combustion)
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19 pages, 6692 KiB  
Article
Measurement of Heat Transfer and Flow Resistance for a Packed Bed of Horticultural Products with the Implementation of a Single Blow Technique
by Adam Łapiński, Kamil Śmierciew, Huiming Zou and Dariusz Butrymowicz
Processes 2021, 9(12), 2151; https://doi.org/10.3390/pr9122151 - 28 Nov 2021
Viewed by 1668
Abstract
This paper provides the practical implementation of the single blow technique as an effective approach of average convective heat transfer coefficient measurement for a packed bed of horticultural products. The measurement approach was positively validated for the case of a packed bed of [...] Read more.
This paper provides the practical implementation of the single blow technique as an effective approach of average convective heat transfer coefficient measurement for a packed bed of horticultural products. The measurement approach was positively validated for the case of a packed bed of balls. The presented results cover heat transfer coefficient results for carrots stored in packed beds for two various arrangements (regular and irregular) and bed of apples under conditions of various turbulent intensity at the inlet to the bed. The turbulent intensity (defined as the ratio of the root mean square of the turbulent fluctuation of the air velocity to the mean air velocity) varied from 0.02 to 0.14. The applied velocity ranges for the tests refers to the conventional storage conditions. The heat transfer correlations were proposed based on the obtained results for each arrangement. It was demonstrated that due to flow laminarization inside the bed, the turbulence intensity has no significant effect on heat transfer inside the bed. Heat transfer enhancement of up to 25% was demonstrated for the case of the irregular carrot arrangement in the tested bed. The flow resistance correlations were additionally proposed for the tested beds. It was demonstrated that the product arrangement does not produce an important effect on the pressure drop. Full article
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30 pages, 9939 KiB  
Article
Applicability of Constitutive Models to Describing the Compressibility of Mining Backfill: A Comparative Study
by Ruofan Wang, Feitao Zeng and Li Li
Processes 2021, 9(12), 2139; https://doi.org/10.3390/pr9122139 - 26 Nov 2021
Cited by 7 | Viewed by 2126
Abstract
The compressibility of mining backfill governs its resistance to the closure of surrounding rock mass, which should be well reflected in numerical modeling. In most numerical simulations of backfill, the Mohr–Coulomb elasto-plastic model is used, but is constantly criticized for its poor representativeness [...] Read more.
The compressibility of mining backfill governs its resistance to the closure of surrounding rock mass, which should be well reflected in numerical modeling. In most numerical simulations of backfill, the Mohr–Coulomb elasto-plastic model is used, but is constantly criticized for its poor representativeness to the mechanical response of geomaterials. Finding an appropriate constitutive model to better represent the compressibility of mining backfill is critical and necessary. In this paper, Mohr–Coulomb elasto-plastic model, double-yield model, and Soft Soil model are briefly recalled. Their applicability to describing the backfill compressibility is then assessed by comparing numerical and experimental results of one-dimensional consolidation and consolidated drained triaxial compression tests made on lowly cemented backfills available in the literature. The comparisons show that the Soft Soil model can be used to properly describe the experimental results while the application of the Mohr–Coulomb model and double-yield model shows poor description on the compressibility of the backfill submitted to large and cycle loading. A further application of the Soft Soil model to the case of a backfilled stope overlying a sill mat shows stress distributions close to those obtained by applying the Mohr–Coulomb model when rock wall closure is absent. After excavating the underlying stope, rock wall closure is generated and exercises compression on the overlying backfill. Compared to the results obtained by applying the Soft Soil model, an application of the Mohr–Coulomb model tends to overestimate the stresses in the backfill when the mine depth is small and underestimate the stresses when the mine depth is large due to the poor description of fill compressibility. The Soft Soil model is recommended to describe the compressibility of uncemented or lightly cemented backfill with small cohesions under external compressions associated with rock wall closure. Full article
(This article belongs to the Special Issue Numerical Modeling in Civil and Mining Geotechnical Engineering)
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31 pages, 22815 KiB  
Article
Development of a General PAT Strategy for Online Monitoring of Complex Mixtures—On the Example of Natural Product Extracts from Bearberry Leaf (Arctostaphylos uva-ursi)
by Christoph Jensch, Larissa Knierim, Martin Tegtmeier and Jochen Strube
Processes 2021, 9(12), 2129; https://doi.org/10.3390/pr9122129 - 25 Nov 2021
Cited by 7 | Viewed by 2253
Abstract
For the first time, a universally applicable and methodical approach from characterization to a PAT concept for complex mixtures is conducted—exemplified on natural products extraction processes. Bearberry leaf (Arctostaphylos uva-ursi) extract is chosen as an example of a typical complex mixture [...] Read more.
For the first time, a universally applicable and methodical approach from characterization to a PAT concept for complex mixtures is conducted—exemplified on natural products extraction processes. Bearberry leaf (Arctostaphylos uva-ursi) extract is chosen as an example of a typical complex mixture of natural plant origin and generalizable in its composition. Within the quality by design (QbD) based process development the development and implementation of a concept for process analytical technology (PAT), a key enabling technology, is the next necessary step in risk and quality-based process development and operation. To obtain and provide an overview of the broad field of PAT, the development process is shown on the example of a complex multi-component plant extract. This study researches the potential of different process analytical technologies for online monitoring of different component groups and classifies their possible applications within the framework of a QbD-based process. Offline and online analytics are established on the basis of two extraction runs. Based on this data set, PLS models are created for the spectral data, and correlations are conducted for univariate data. In a third run, the prediction potential is researched. Conclusively, the results of this study are arranged in the concept of a holistic quality and risk-based process design and operation concept. Full article
(This article belongs to the Special Issue Towards Autonomous Operation of Biologics and Botanicals)
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18 pages, 5095 KiB  
Article
Zn–Al Layered Double Hydroxides Synthesized on Aluminum Foams for Fluoride Removal from Water
by Yuliu Li, Riccardo Narducci, Alessandra Varone, Saulius Kaciulis, Eleonora Bolli and Roberto Pizzoferrato
Processes 2021, 9(12), 2109; https://doi.org/10.3390/pr9122109 - 24 Nov 2021
Cited by 4 | Viewed by 2146
Abstract
Fluoride excess in water represents an environmental issue and a risk for human health since it can cause several diseases, such as fluorosis, osteoporosis, and damage of the nervous system. Layered double hydroxides (LDHs) can be exploited to remove this contaminant from water [...] Read more.
Fluoride excess in water represents an environmental issue and a risk for human health since it can cause several diseases, such as fluorosis, osteoporosis, and damage of the nervous system. Layered double hydroxides (LDHs) can be exploited to remove this contaminant from water by taking advantage of their high ion-exchange capability. LDHs are generally mixed with polluted water in the form of powders, which then cause the problem of uneasy separation of the contaminated LDH sludge from the purified liquid. In this work, Zn–Al LDH films were directly grown in situ on aluminum foams that acted both as the reactant and substrate. This method enabled the removal of fluoride ions by simple immersion, with ensuing withdrawal of the foam from the de-contaminated water. Different LDH synthesis methods and aluminum foam types were investigated to improve the adsorption process. The contact time, initial fluoride concentration, adsorbent dosage, and pH were studied as the parameters that affect the fluoride adsorption capacity and efficiency. The highest absorption efficiency of approximately 70% was obtained by using two separate growth methods after four hours, and it effectively reduced the fluoride concentration from 3 mg/L to 1.1 mg/L, which is below the threshold value set by WHO for drinking water. Full article
(This article belongs to the Section Materials Processes)
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12 pages, 4591 KiB  
Article
Optimalization of Design Parameters of Experimental Installation Concerning Preparation of Liquid Feed Mixtures
by Pavel Solonscikov, Jan Barwicki, Peter Savinyh and Marek Gaworski
Processes 2021, 9(12), 2104; https://doi.org/10.3390/pr9122104 - 23 Nov 2021
Cited by 1 | Viewed by 1057
Abstract
The article describes the initial conditions for the development of universal mechanization means for the process of mixing dry and liquid components. The essence of the method is to study the motion of a particle with different constructive and physical properties of the [...] Read more.
The article describes the initial conditions for the development of universal mechanization means for the process of mixing dry and liquid components. The essence of the method is to study the motion of a particle with different constructive and physical properties of the medium. The mathematical model of particle motion is based on theoretical mechanics and hydraulics. In this case, the main purpose of the study is to find the optimal design parameters for the installation. At the beginning, a theoretical analysis of the installation was carried out using the methods of classical mechanics and hydraulics. Experimental studies were carried out in several stages. At the beginning, one-factor experiments were conducted, followed by allocating the main factors and determining their interaction. Then, using the methods of planning the experiment, we obtained the regression equations and further optimized the parameters to summarize the main findings of the article. Modern installations should have versatility in any technological line; for example, an installation is presented that can not only mix, but further transport the mixture like a conventional pump, while providing a dosing device that is necessary for the feeding of dry components. Theoretical studies have been carried out in which the design of the impeller is substantiated at various speeds. Experimental studies to determine the design parameters of the installation are in continuous operation. The degree of homogeneity was Θ = 74%, with β2 = 80 … 100° and βst = 65 … 102°, while the value of the consumption of electrical energy is equal to Eel = 0.265 … 0.28 kWh/t. Full article
(This article belongs to the Section Process Control and Monitoring)
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19 pages, 2881 KiB  
Article
Biodesulfurization of Dibenzothiophene and Its Alkylated Derivatives in a Two-Phase Bubble Column Bioreactor by Resting Cells of Rhodococcus erythropolis IGTS8
by George Prasoulas, Konstantinos Dimos, Panayiotis Glekas, Styliani Kalantzi, Stamatis Sarris, Chrysovalantis Templis, Konstantinos Vavitsas, Dimitris G. Hatzinikolaou, Nikolaos Papayannakos, Dimitris Kekos and Diomi Mamma
Processes 2021, 9(11), 2064; https://doi.org/10.3390/pr9112064 - 18 Nov 2021
Cited by 7 | Viewed by 2985
Abstract
Biodesulfurization (BDS) is considered a complementary technology to the traditional hydrodesulfurization treatment for the removal of recalcitrant sulfur compounds from petroleum products. BDS was investigated in a bubble column bioreactor using two-phase media. The effects of various process parameters, such as biocatalyst age [...] Read more.
Biodesulfurization (BDS) is considered a complementary technology to the traditional hydrodesulfurization treatment for the removal of recalcitrant sulfur compounds from petroleum products. BDS was investigated in a bubble column bioreactor using two-phase media. The effects of various process parameters, such as biocatalyst age and concentration, organic fraction percentage (OFP), and type of sulfur compound—namely, dibenzothiophene (DBT), 4-methyldibenzothiophene (4-MDBT), 4,6-dimethyldibenzothiophene (4,6-DMDBT), and 4,6-diethyldibenzothiophene (4,6-DEDBT)—were evaluated, using resting cells of Rhodococcus erythropolis IGTS8. Cells derived from the beginning of the exponential growth phase of the bacterium exhibited the highest biodesulfurization efficiency and rate. The biocatalyst performed better in an OFP of 50% v/v. The extent of DBT desulfurization was dependent on cell concentration, with the desulfurization rate reaching its maximum at intermediate cell concentrations. A new semi-empirical model for the biphasic BDS was developed, based on the overall Michaelis-Menten kinetics and taking into consideration the deactivation of the biocatalyst over time, as well as the underlying mass transfer phenomena. The model fitted experimental data on DBT consumption and 2-hydroxibyphenyl (2-HBP) accumulation in the organic phase for various initial DBT concentrations and different organosulfur compounds. For constant OFP and biocatalyst concentration, the most important parameter that affects BDS efficiency seems to be biocatalyst deactivation, while the phenomenon is controlled by the affinities of biodesulfurizing enzymes for the different organosulfur compounds. Thus, desulfurization efficiency decreased with increasing initial DBT concentration, and in inverse proportion to increases in the carbon number of alkyl substituent groups. Full article
(This article belongs to the Section Biological Processes and Systems)
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16 pages, 3071 KiB  
Article
Optimization and Modeling of Ammonia Nitrogen Removal from High Strength Synthetic Wastewater Using Vacuum Thermal Stripping
by Arif Reza and Lide Chen
Processes 2021, 9(11), 2059; https://doi.org/10.3390/pr9112059 - 17 Nov 2021
Cited by 6 | Viewed by 2955
Abstract
Waste streams with high ammonia nitrogen (NH3-N) concentrations are very commonly produced due to human intervention and often end up in waterbodies with effluent discharge. The removal of NH3-N from wastewater is therefore of utmost importance to alleviate water [...] Read more.
Waste streams with high ammonia nitrogen (NH3-N) concentrations are very commonly produced due to human intervention and often end up in waterbodies with effluent discharge. The removal of NH3-N from wastewater is therefore of utmost importance to alleviate water quality issues including eutrophication and fouling. In the present study, vacuum thermal stripping of NH3-N from high strength synthetic wastewater was conducted using a rotary evaporator and the process was optimized and modeled using response surface methodology (RSM) and RSM–artificial neural network (ANN) approaches. RSM was first employed to evaluate the process performance using three independent variables, namely pH, temperature (°C) and stripping time (min), and the optimal conditions for NH3-N removal (response) were determined. Later, the obtained data from the designed experiments of RSM were used to train the ANN for predicting the responses. NH3-N removal was found to be 97.84 ± 1.86% under the optimal conditions (pH: 9.6, temperature: 65.5 °C, and stripping time: 59.6 min) and was in good agreement with the values predicted by RSM and RSM–ANN models. A statistical comparison between the models revealed the better predictability of RSM–ANN than that of the RSM. To the best of our knowledge, this is the first attempt comparing the RSM and RSM–ANN in vacuum thermal stripping of NH3-N from wastewater. The findings of this study can therefore be useful in designing and carrying out the vacuum thermal stripping process for efficient removal of NH3-N from wastewater under different operating conditions. Full article
(This article belongs to the Special Issue Emerging Technologies for Water and Wastewater Treatment)
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15 pages, 6168 KiB  
Article
Closed-Cell Powder Metallurgical Aluminium Foams Reinforced with 3 vol.% SiC and 3 vol.% Graphite
by Jaroslav Kováčik, Martin Nosko, Natália Mináriková, František Simančík and Jaroslav Jerz
Processes 2021, 9(11), 2031; https://doi.org/10.3390/pr9112031 - 13 Nov 2021
Cited by 9 | Viewed by 3341
Abstract
Closed-cell aluminium foams (nominal composition: AlSi12Mg0.6Fe0.3) were prepared by the powder metallurgical route (using 0.4 wt.% TiH2 untreated powder as the foaming agent). Pure foams and foams with the addition of 3 vol.% graphite or SiC powder were prepared. The microstructure and [...] Read more.
Closed-cell aluminium foams (nominal composition: AlSi12Mg0.6Fe0.3) were prepared by the powder metallurgical route (using 0.4 wt.% TiH2 untreated powder as the foaming agent). Pure foams and foams with the addition of 3 vol.% graphite or SiC powder were prepared. The microstructure and mechanical properties of the prepared aluminium foams containing reinforcing particles were investigated at constant density and compared to those of the pure foam. Vibration measurements were performed to determine the damping properties and modulus of elasticity of the foams. Uniaxial compression tests were performed to determine the following mechanical properties: collapse stress, efficiency of energy absorption, plateau length and densification strain of the foams. All the foams behaved in a brittle manner during compression. Finally, the effect of admixed graphite and SiC powders on the properties of the investigated foam was evaluated, discussed and modelled. The addition of powders changed all investigated properties of the foams. Only the efficiency of energy absorption at constant density was almost identical. Full article
(This article belongs to the Special Issue Foam Matrix Composites: Preparation and Application)
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10 pages, 661 KiB  
Article
Influence of the Preliminary Storage on Methane Yield of Anaerobic Digestion of the Organic Fraction of Municipal Solid Waste
by Domenica Pangallo, Altea Pedullà, Demetrio Antonio Zema and Paolo S. Calabrò
Processes 2021, 9(11), 2017; https://doi.org/10.3390/pr9112017 - 11 Nov 2021
Cited by 4 | Viewed by 1583
Abstract
Anaerobic digestion (AD) is a suitable management option for the energy valorization of many wastes, including the organic fraction of municipal solid waste (OFMSW). However, in some cases, long storage after the separate collection of this waste is required for management reasons, especially [...] Read more.
Anaerobic digestion (AD) is a suitable management option for the energy valorization of many wastes, including the organic fraction of municipal solid waste (OFMSW). However, in some cases, long storage after the separate collection of this waste is required for management reasons, especially when the amount of waste to be treated temporarily exceeds the capacity of available AD plants. This study evaluates the biochemical methane potential (BMP) of the OFMSW after preliminary storage of 2, 6, and 10 days, in order to assess whether they are still suitable for AD or not. Moreover, the accuracy of three kinetic models (first order, Gompertz, and logistic models) in estimating the methane yield of stored OFMSW is tested. The resulting methane yield was between about 500 and 650 NmL·gVS−1 and slightly increased with the increase of the storage time after collection. Overall, this study has demonstrated that storage of OFMSW, when the collected amount of solid waste exceeds the treatment capacity of AD plants, a storage time up to 10 days does not impact the methane yield of the process. Full article
(This article belongs to the Special Issue Lignocellulose Pretreatment and Utilization)
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18 pages, 39351 KiB  
Article
In Situ Observation of the Carbothermic Reduction and Foaming of Slags in Silicomanganese Production
by Vincent Canaguier and Merete Tangstad
Processes 2021, 9(11), 2020; https://doi.org/10.3390/pr9112020 - 11 Nov 2021
Cited by 1 | Viewed by 1579
Abstract
The carbothermic reduction of slag in silicomanganese production is accompanied by the release of carbon monoxide. This gas can accumulate as bubbles within the slag, leading to foaming and, potentially, disturbances to furnace operation. This study investigated the reduction in the slag together [...] Read more.
The carbothermic reduction of slag in silicomanganese production is accompanied by the release of carbon monoxide. This gas can accumulate as bubbles within the slag, leading to foaming and, potentially, disturbances to furnace operation. This study investigated the reduction in the slag together with its foaming using a sessile drop furnace. Five silicomanganese slags produced from industrial raw materials (Assmang ore, Comilog ore, high-carbon FeMn slag with quartz, and FeS additions) were reduced by a graphite substrate at isothermal conditions (i.e., 1540–1660 °C) under CO atmosphere. The reduction reaction was tracked by photographing the slag droplet, and the cyclic expansion and burst of the droplet were used to estimate the gas evolution. The reacted samples were analyzed by wavelength-dispersive X-ray spectroscopy (WDS) to determine MnO and SiO2 reduction. While no foaming was observed using Comilog ore, extensive retention of CO in the slag phase was observed when using Assmang ore or Assmang with high-carbon FeMn slag. The beginning of foaming was attributed to an increase in the reaction rate; the absence of foaming when using Comilog can be attributed to the acidity of the charge. Addition of sulfur to the Comilog-based charge did not influence the reduction. Full article
(This article belongs to the Section Materials Processes)
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16 pages, 2335 KiB  
Article
Miniaturization of Anthracene-Containing Nonapeptides for Selective Precipitation/Recovery of Metallic Gold from Aqueous Solutions Containing Gold and Platinum Ions
by Kin-ya Tomizaki, Tatsuki Tonoda, Shungo Teramura, Haruka Okazaki, Takahito Imai and Masahiro Asano
Processes 2021, 9(11), 2010; https://doi.org/10.3390/pr9112010 - 10 Nov 2021
Cited by 1 | Viewed by 1432
Abstract
The separation and recovery of noble metals is increasingly of interest, in particular the recovery of gold nanocrystals, which have applications in medicine and industry. Typically, metal recovery is performed using liquid–liquid extraction or electrowinning. However, it is necessary to develop noble metal [...] Read more.
The separation and recovery of noble metals is increasingly of interest, in particular the recovery of gold nanocrystals, which have applications in medicine and industry. Typically, metal recovery is performed using liquid–liquid extraction or electrowinning. However, it is necessary to develop noble metal recovery systems providing high selectivity in conjunction with a one-pot setup, ready product recovery, and the use of dilute aqueous solutions. In prior work, our group developed a selective gold recovery process using peptides. This previous research showed that RU065, a nonapeptide containing an anthracene moiety (at a concentration of 2.0 × 10−4 M), is capable of selective reduction of HAuCl4 to recover gold from a solution of HAuCl4 and H2PtCl6, each at 5.0 × 10−5 M. However, peptide molecules are generally costly to synthesize, and therefore it is important to determine the minimum required structural features to design non-peptide anthracene derivatives that could reduce operational costs. In this study, we used RU065 together with 23 of its fragment peptides and investigated the selective precipitation/recovery of metallic gold. RU0654–8, a fragment peptide comprising five amino acid residues (having two lysine, one L-isoleusine, and one L-alanine residue (representing six amide groups) along with an L-2-anthrylalanine residue) provided an Au/Pt atomic ratio of approximately 8, which was comparable to that for the full-length original RU065. The structural features identified in this study are expected to contribute to the design of non-peptide anthracene derivatives for low-cost, one-pot selective gold recovery. Full article
(This article belongs to the Special Issue The Amazing World of Peptide Engineering)
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16 pages, 9502 KiB  
Article
Investigation of the Mechanical Behavior of Electrodes after Calendering and Its Influence on Singulation and Cell Performance
by Dominik Mayer, Ann-Kathrin Wurba, Benjamin Bold, Jonathan Bernecker, Anna Smith and Jürgen Fleischer
Processes 2021, 9(11), 2009; https://doi.org/10.3390/pr9112009 - 10 Nov 2021
Cited by 15 | Viewed by 4864
Abstract
Battery cell production is a complex process chain with interlinked manufacturing processes. Calendering in particular has an enormous influence on the subsequent manufacturing steps and final cell performance. However, the effects on the mechanical properties of the electrode, in particular, have been insufficiently [...] Read more.
Battery cell production is a complex process chain with interlinked manufacturing processes. Calendering in particular has an enormous influence on the subsequent manufacturing steps and final cell performance. However, the effects on the mechanical properties of the electrode, in particular, have been insufficiently investigated. For this reason, the impact of different densification rates during calendering on the electrochemical cell performance of NMC811 (LiNi0.8Mn0.1Co0.1O2) half-cells are investigated to identify the relevant calendering parameters. Based on this investigation, an experimental design has been derived. Electrode elongations after calendering in and orthogonal to the running direction of the NMC811 cathode are investigated in comparison with a hard carbon anode after calendering. Elongations orthogonal to the machine direction are observed to have no major dependencies on the compaction rate during calendering. In the machine direction, however, significant elongation occurs as a dependency of the compaction rate for both the hard carbon anode and the NMC811. In addition, the geometric shape of the NMC811 electrodes after separation into individual sheets is investigated with regard to different compaction rates during calendering. It is shown that the corrugations that occur during calendering are propagated into the single electrode, depending on the compaction rate. Full article
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16 pages, 3126 KiB  
Article
Functional Ingredients and Food Preservative in Immature Persimmon “Tekka-Kaki”
by Akiyoshi Sawabe, Natsumi Ohnishi, Sachiko Yoshioka, Kunihiro Kusudo, Kenichi Kanno and Yoshiyuki Watanabe
Processes 2021, 9(11), 1989; https://doi.org/10.3390/pr9111989 - 8 Nov 2021
Cited by 4 | Viewed by 2121
Abstract
Immature persimmons are unripe fruits that are cut off during the persimmon cultivation process and immediately discarded, amounting to an annual fruit loss of approximately 100 to 400 kg per 1000 m2. The purpose of this study was to make effective [...] Read more.
Immature persimmons are unripe fruits that are cut off during the persimmon cultivation process and immediately discarded, amounting to an annual fruit loss of approximately 100 to 400 kg per 1000 m2. The purpose of this study was to make effective use of unused resources, namely, immature persimmons, and attempt to use them as food additives. In this study, we studied the Tone Wase (fully astringent persimmon) and Fuyu (fully sweet persimmon) cultivars. As a result, we performed a component analysis of the immature persimmons, isolating 12 compounds, of which two were newly identified. Differences in the components and their contents were found between cultivars and between the peel and flesh. To effectively use immature persimmons as food for the elderly, we searched for active substances that inhibit AGE formation and found that extracts of immature persimmons and isolated compounds showed high activity. In particular, high activity was observed for catechin and its polymeric form, procyanidin. Regarding the inhibition of aroma deterioration, 5 mg/L of gallic acid in octadecane was found to be the optimal condition for the inhibition of citral deterioration. As for antimicrobial activity, we found that extracts at a concentration of 500 mg/L had no antimicrobial effect. Based on these findings, we made a microencapsulation process, and plan to advance to the clinical trial study in future. These findings confirmed the effectiveness of immature persimmons, which are an unused resource, and reveal their potential as a food for the elderly and as a food additive in other food products, which we hope will lead to new industrial innovations. Full article
(This article belongs to the Special Issue Plants as Functional Food Ingredients and Food Preservative)
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12 pages, 2936 KiB  
Article
The Biological Effects of Ozone Gas on Soft and Hard Dental Tissues and the Impact on Human Gingival Fibroblasts and Gingival Keratinocytes
by Alin Daniel Floare, Alexandra Denisa Scurtu, Octavia Iulia Balean, Doina Chioran, Roxana Buzatu, Ruxandra Sava Rosianu, Vlad Tiberiu Alexa, Daniela Jumanca, Laura-Cristina Rusu, Robert Cosmin Racea, Dorina Coricovac, Iulia Pinzaru, Cristina Adriana Dehelean and Atena Galuscan
Processes 2021, 9(11), 1978; https://doi.org/10.3390/pr9111978 - 5 Nov 2021
Cited by 5 | Viewed by 2521
Abstract
Ozone is an allotropic form of oxygen, so in the medical field ozone therapy has special effects. Starting from the premise that bio-oxidative ozone therapy reduces the number of bacteria, in the present study two approaches were proposed: to evaluate the biological effects [...] Read more.
Ozone is an allotropic form of oxygen, so in the medical field ozone therapy has special effects. Starting from the premise that bio-oxidative ozone therapy reduces the number of bacteria, in the present study two approaches were proposed: to evaluate the biological effects of ozone gas on the tooth enamel remineralization process and to demonstrate its impact on the morphology and confluence of human primary gingival cells, namely keratinocytes (PGK) and fibroblasts (HGF). The ozone produced by HealOzone was applied in vivo to 68 M1s (first permanent molars), both maxillary and mandibular, on the occlusal surfaces at pit and fissure. The molars included in the study recorded values between 13 and 24 according to the DIAGNOdent Pen 2190 scale, this being the main inclusion/exclusion criterion for the investigated molars. Because the gas can make contact with primary gingival cells during the ozonation process, both human gingival fibroblasts and keratinocytes were exposed to different doses of ozone (20 s, 40 s, 60 s), and its effects were observed with the Olympus IX73 inverted microscope. The contact of ozone with the human primary gingival cells demonstrates cell sensitivity to the action of ozone, this being higher in fibroblasts compared to keratinocytes, but it is not considered toxic because all the changes are reversible at 48 h after exposure. Full article
(This article belongs to the Special Issue Basic, Biological and Therapeutic Processes of Ozone Therapy)
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16 pages, 3368 KiB  
Article
Highly Stable and Nontoxic Lanthanum-Treated Activated Palygorskite for the Removal of Lake Water Phosphorus
by Bhabananda Biswas and Ravi Naidu
Processes 2021, 9(11), 1960; https://doi.org/10.3390/pr9111960 - 2 Nov 2021
Cited by 2 | Viewed by 1864
Abstract
Nutrient pollution of surface water, such as excess phosphate loading on lake surface water, is a significant issue that causes ecological and financial damage. Despite many technologies that can remove available phosphate, such as material-based adsorption of those available phosphate ions, the development [...] Read more.
Nutrient pollution of surface water, such as excess phosphate loading on lake surface water, is a significant issue that causes ecological and financial damage. Despite many technologies that can remove available phosphate, such as material-based adsorption of those available phosphate ions, the development of a material that can trap them from the surface water is worth doing, considering other aspects. These aspects are: (i) efficient adsorption by the material while it settles down to the water column, and (ii) the material itself is not toxic to the lake natural microorganism. Considering these aspects, we developed a trace lanthanum-grafted surface-modified palygorskite, a fibrous clay mineral. It adsorbed a realistic amount of phosphate from the lake water (typically 0.13–0.22 mg/L). The raw and modified palygorskite (Pal) includes unmodified Australian Pal, heated (at ~400 °C) Pal, and acid (with 3 M HCl)-treated Pal. Among them, while acid-treated Pal grafted a lower amount of La, it had a higher adsorption capacity (1.243 mg/g) and a quicker adsorption capacity in the time it took to travel to the bottom of the lake (97.6% in 2 h travel time), indicating the adsorption role of both La and clay mineral. The toxicity of these materials was recorded null, and in some period of the incubation of the lake microorganism with the material mixture, La-grafted modified clays increased microbial growth. As a total package, while a high amount of La on the already available material could adsorb a greater amount of phosphate, in this study a trace amount of La on modified clays showed adsorption effectiveness for the realistic amount of phosphate in lake water without posing added toxicity. Full article
(This article belongs to the Special Issue Novel Adsorbent for Environmental Remediation)
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13 pages, 1173 KiB  
Article
Ammonium and Phosphate Recovery in a Three Chambered Microbial Electrolysis Cell: Towards Obtaining Struvite from Livestock Manure
by Míriam Cerrillo, Laura Burgos, Joan Noguerol, Victor Riau and August Bonmatí
Processes 2021, 9(11), 1916; https://doi.org/10.3390/pr9111916 - 27 Oct 2021
Cited by 6 | Viewed by 2381
Abstract
Ammonia and phosphate, which are present in large quantities in waste streams such as livestock manure, are key compounds in fertilization activities. Their recovery will help close natural cycles and take a step forward in the framework of a circular economy. In this [...] Read more.
Ammonia and phosphate, which are present in large quantities in waste streams such as livestock manure, are key compounds in fertilization activities. Their recovery will help close natural cycles and take a step forward in the framework of a circular economy. In this work, a lab-scale three-chambered microbial electrolysis cell (MEC) has been operated in continuous mode for the recovery of ammonia and phosphate from digested pig slurry in order to obtain a nutrient concentrated solution as a potential source of fertilizer (struvite). The maximum average removal efficiencies for ammonium and phosphate were 20% ± 4% and 36% ± 10%, respectively. The pH of the recovered solution was below 7, avoiding salt precipitation in the reactor. According to Visual MINTEQ software modelling, an increase of pH value to 8 outside the reactor would be enough to recover most of the potential struvite (0.21 mmol L−1 d−1), while the addition of up to 0.2 mM of magnesium to the nutrient recovered solution would enhance struvite production from 5.6 to 17.7 mM. The application of three-chambered MECs to the recovery of nutrients from high strength wastewater is a promising technology to avoid ammonia production through industrial processes or phosphate mineral extraction and close nutrient natural cycles. Full article
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20 pages, 5847 KiB  
Article
Purification of Textile Effluents Containing C.I. Acid Violet 1: Adsorptive Removal versus Hydrogen Peroxide and Peracetic Acid Based Advanced Oxidation
by Monika Wawrzkiewicz, Urszula Kotowska and Aneta Sokół
Processes 2021, 9(11), 1911; https://doi.org/10.3390/pr9111911 - 26 Oct 2021
Cited by 8 | Viewed by 2092
Abstract
Textile effluent containing azo dyes such as C.I. Acid Violet 1 (AV1) can be degraded to toxic aromatic amines in the environment. Thus, there is a legitimate need to treat such effluents before they are discharged to surface waters. Two methods were proposed [...] Read more.
Textile effluent containing azo dyes such as C.I. Acid Violet 1 (AV1) can be degraded to toxic aromatic amines in the environment. Thus, there is a legitimate need to treat such effluents before they are discharged to surface waters. Two methods were proposed to remove AV1 from aqueous solutions: adsorption and advanced oxidation processes (AOPs). The sorption capacity of the strongly basic anion exchanger Purolite A520E of the polystyrene matrix determined from the Langmuir isotherm model was found to be 835 mg/g, while that of Lewatit S5428 of the polyacrylamide matrix Freundlich model seems to be more appropriate for describing the experimental data. The pseudo-second-order kinetic model and external diffusion are the rate limiting steps of adsorption. The removal efficiency of AV1 by the anion exchangers was higher than 99% after 40 min of phase contact time. AOPs involved the usage of hydrogen peroxide and peracetic acid (PAA) as oxidizing agents, while Fe2+ and simulated sunlight were used as oxidizing activators. AV1 oxidation followed the pseudo-first-order kinetics, and the systems with the highest values of the rate constants turned out to be those in which Fe2+ was present. The efficiency of oxidation measured by the degree of decolorization in the systems with Fe2+ was higher than 99% after 10–60 min. AV1 mineralization was slower, but after 120 min of oxidation it was higher than 98% in the H2O2/Fe2+, PAA/Fe2+ and PAA/Fe2+/sunlight systems. Full article
(This article belongs to the Special Issue Various Adsorbents for Water Purification Processes, Volume II)
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20 pages, 4674 KiB  
Article
Novel Insights on the Sustainable Wet Mode Fractionation of Black Soldier Fly Larvae (Hermetia illucens) into Lipids, Proteins and Chitin
by Harish Karthikeyan Ravi, Côme Guidou, Jérôme Costil, Christophe Trespeuch, Farid Chemat and Maryline Abert Vian
Processes 2021, 9(11), 1888; https://doi.org/10.3390/pr9111888 - 22 Oct 2021
Cited by 6 | Viewed by 4905
Abstract
The black soldier fly larvae (BSFL) is a sustainable ingredient for feed applications, biofuels, composite materials and other biobased products. Processing BSFL to obtain lipid and protein fractions with enhanced functional properties as a suitable replacement for conventional feed ingredients has gained considerable [...] Read more.
The black soldier fly larvae (BSFL) is a sustainable ingredient for feed applications, biofuels, composite materials and other biobased products. Processing BSFL to obtain lipid and protein fractions with enhanced functional properties as a suitable replacement for conventional feed ingredients has gained considerable momentum. In this regard, a novel and sustainable wet mode fractionation (WMF) scheme for BSFL was explored. Fresh BSFL were steam blanched and pulped to obtain BSFL juice and juice press cake. Subsequent treatment of BSFL juice employing homogenization or enzyme incubation and further centrifugation resulted in the obtention of four different BSFL fractions (Lipid—LF; Cream—CF; Aqueous—AF; and Solid—SF). Total energy consumption for a batch BSFL (500 g) WMF process was 0.321 kWh. Aqueous and solid fractions were the predominant constituents of BSFL juice. Lauric acid (44.52–49.49%) and linoleic acid (19.12–20.12%) were the primary fatty acids present in BSFL lipids. Lipid hydrolysis was observed in lipids belonging to the solid (free fatty acids > triacylglycerides) and cream fractions. Aqueous fraction proteins (ctrl) displayed superior emulsion stability and foam capacity than other treatments. Juice press cake retained 60% of the total chitin content and the rest, 40%, was found in the solid fraction (ctrl). The material distribution of principal constituents in different fractions of the WMF process and amino acid profile was elucidated. Overall, the versatile WMF process proposed in this study involves simple unit operations to obtain functional ingredients from BSFL, which can be further explored by researchers and industry stakeholders. Full article
(This article belongs to the Special Issue Redesign Processes in the Age of the Fourth Industrial Revolution)
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