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Processes, Volume 6, Issue 4 (April 2018)

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Cover Story (view full-size image) An increasing number of researchers and professionals are struggling with converting processes from [...] Read more.
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Open AccessArticle Experimental Investigation of the Mechanical Behaviors of Grouted Sand with UF-OA Grouts
Processes 2018, 6(4), 37; https://doi.org/10.3390/pr6040037
Received: 29 March 2018 / Revised: 14 April 2018 / Accepted: 15 April 2018 / Published: 19 April 2018
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Abstract
A detailed understanding of the engineering properties for grouted sand is a key concern in foundation engineering projects containing sand layers. In this research, experiments of grouting with various grain sizes of sand specimens using a new type of improved chemical material-urea formaldehyde
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A detailed understanding of the engineering properties for grouted sand is a key concern in foundation engineering projects containing sand layers. In this research, experiments of grouting with various grain sizes of sand specimens using a new type of improved chemical material-urea formaldehyde resin mixed with oxalate curing agent (UF-OA), which has rarely been used as grout in the reinforcement of soft foundations, were conducted on the basis of a self-developed grouting test system. After grouting tests, the effects on the mechanical behaviors of grouted sand specimens were investigated through uniaxial compression tests considering the grain size, the presence or absence of initial water in sand, and the curing time for grouted sand. Experimental results show that with the increase in the grain size and the presence of initial water in the sand specimen, the values of uniaxial compressive strength (UCS) and elastic moduli (E) of the grouted specimens decreased obviously, indicating that the increase of grain size and the presence of initial water have negative impacts on the mechanical behaviors of grouted sand; the peak strains (εc) were almost unchanged after 14 days of curing; no brittle failure behavior occurred in the grouted specimens, and desirable ductile failure characteristics were distinct after uniaxial compression. These mechanical behaviors were significantly improved after 14 days of curing. The micro-structural properties obtained by scanning electron microscopy (SEM) of the finer grouted sand indicate preferable filling performance to some extent, thereby validating the macroscopic mechanical behaviors. Full article
(This article belongs to the Special Issue Fluid Flow in Fractured Porous Media)
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Open AccessArticle Laboratory Investigation of Granite Permeability after High-Temperature Exposure
Processes 2018, 6(4), 36; https://doi.org/10.3390/pr6040036
Received: 13 March 2018 / Revised: 13 April 2018 / Accepted: 17 April 2018 / Published: 19 April 2018
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Abstract
This study experimentally analysed the influence of temperature levels (200, 300, 400, 500, 600, and 800 °C) on the permeability of granite samples. At each temperature level, the applied confining pressure was in the range of 10–30 MPa, and the inlet hydraulic pressure
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This study experimentally analysed the influence of temperature levels (200, 300, 400, 500, 600, and 800 °C) on the permeability of granite samples. At each temperature level, the applied confining pressure was in the range of 10–30 MPa, and the inlet hydraulic pressure varied below the corresponding confining pressure. The results are as follows: (i) With an increase in the temperature level, induced micro-fractures in the granites develop, and the decrement ratios of both the P-wave velocity and the density of the granite increase; (ii) The relationship between the volume flow rate and the pressure gradient is demonstrably linear and fits very well with Darcy’s law. The equivalent permeability coefficient shows an increasing trend with the temperature, and it can be best described using the mathematical expression K0 = A × 1.01T; (iii) For a given temperature level, as the confining pressure increases, the transmissivity shows a decrease, and the rate of its decrease diminishes gradually. Full article
(This article belongs to the Special Issue Fluid Flow in Fractured Porous Media)
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Open AccessArticle Structure Manipulation of Carbon Aerogels by Managing Solution Concentration of Precursor and Its Application for CO2 Capture
Processes 2018, 6(4), 35; https://doi.org/10.3390/pr6040035
Received: 2 February 2018 / Revised: 1 April 2018 / Accepted: 7 April 2018 / Published: 12 April 2018
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Abstract
A series of carbon aerogels were synthesized by polycondensation of resorcinol and formaldehyde, and their structure was adjusted by managing solution concentration of precursors. Carbon aerogels were characterized by X-ray diffraction (XRD), Raman, Fourier transform infrared spectroscopy (FTIR), N2 adsorption/desorption and scanning
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A series of carbon aerogels were synthesized by polycondensation of resorcinol and formaldehyde, and their structure was adjusted by managing solution concentration of precursors. Carbon aerogels were characterized by X-ray diffraction (XRD), Raman, Fourier transform infrared spectroscopy (FTIR), N2 adsorption/desorption and scanning electron microscope (SEM) technologies. It was found that the pore structure and morphology of carbon aerogels can be efficiently manipulated by managing solution concentration. The relative micropore volume of carbon aerogels, defined by Vmicro/Vtol, first increased and then decreased with the increase of solution concentration, leading to the same trend of CO2 adsorption capacity. Specifically, the CA-45 (the solution concentration of precursors is 45 wt%) sample had the highest CO2 adsorption capacity (83.71 cm3/g) and the highest selectivity of CO2/N2 (53) at 1 bar and 0 °C. Full article
(This article belongs to the Special Issue Transport of Fluids in Nanoporous Materials)
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Open AccessArticle Assessment of Industrial Modules to Design a GFMA Process for Cyanide Recovery Based on a Phenomenological Model
Processes 2018, 6(4), 34; https://doi.org/10.3390/pr6040034
Received: 19 March 2018 / Revised: 4 April 2018 / Accepted: 6 April 2018 / Published: 11 April 2018
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Abstract
Cyanide recovery in the gold-mining industry is a crucial step in terms of the cost of operation. Currently, a process such as AVR (acidification, volatilization and recycling), based on packed towers for stripping and absorption stages, addresses this issue with high levels of
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Cyanide recovery in the gold-mining industry is a crucial step in terms of the cost of operation. Currently, a process such as AVR (acidification, volatilization and recycling), based on packed towers for stripping and absorption stages, addresses this issue with high levels of investment and operational costs. Gas-filled membrane absorption (GFMA) emerges then as an attractive alternative because the stripping and absorption stages can be performed in a single stage, reducing associated investment and operational costs. Despite the advantages of this technology, applications at industrial scale are still emerging. A possible reason is the lack of clear scaling-up methodologies where experimental data can be taken to select the optimum industrial hollow-fiber membrane contactor module (HFMC). The present study proposes a methodology to select adequately between available industrial Liqui-CelTM modules to design a process under optimal operational conditions. The methodology is based on a phenomenological model developed for recovering cyanide by using the GFMA process. Simulation of the Liqui-CelTM industrial membrane modules employed to recover cyanide in the GFMA process, both in a batch arrangement with a feed-flow rate, and in the range 10–125 m3/h, showed that in terms of cyanide recovery there are no differences between the modules tested when they work at the same feed-flow rate. The design criteria to scale-up was determined: to ensure performance at different scales, the length of the transfer unit (HTU) should be kept at different capacities of HFMC modules that comprise the equipment characteristics (mass-transfer area, stream velocities, and mass-transfer coefficient values). Additionally, the number of commercial modules Liqui-CelTM required to treat 57 m3/h and 250 m3/h ensuring a cyanide recovery of 95% was also determined. Finally, the most profitable option (lower pressure drop and module cost) resulted in the use of the 14 × 40 Liqui-CelTM module. Full article
(This article belongs to the Special Issue Membrane Materials, Performance and Processes)
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Open AccessReview Preparation and Potential Applications of Super Paramagnetic Nano-Fe3O4
Processes 2018, 6(4), 33; https://doi.org/10.3390/pr6040033
Received: 14 February 2018 / Revised: 23 March 2018 / Accepted: 3 April 2018 / Published: 9 April 2018
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Abstract
Ferroferric oxide nanoparticle (denoted as Nano-Fe3O4) has low toxicity and is biocompatible, with a small particle size and a relatively high surface area. It has a wide range of applications in many fields such as biology, chemistry, environmental science
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Ferroferric oxide nanoparticle (denoted as Nano-Fe3O4) has low toxicity and is biocompatible, with a small particle size and a relatively high surface area. It has a wide range of applications in many fields such as biology, chemistry, environmental science and medicine. Because of its superparamagnetic properties, easy modification and function, it has become an important material for addressing a number of specific tasks. For example, it includes targeted drug delivery nuclear magnetic resonance (NMR) imaging in biomedical applications and in environmental remediation of pollutants. Few articles describe the preparation and modification of Nano-Fe3O4 in detail. We present an evaluation of preparation methodologies, as the quality of material produced plays an important role in its successful application. For example, with modification of Nano-Fe3O4, the surface activation energy is reduced and good dispersion is obtained. Full article
(This article belongs to the Special Issue Transport of Fluids in Nanoporous Materials)
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Open AccessFeature PaperReview Rotor-Stator Mixers: From Batch to Continuous Mode of Operation—A Review
Processes 2018, 6(4), 32; https://doi.org/10.3390/pr6040032
Received: 16 March 2018 / Revised: 28 March 2018 / Accepted: 30 March 2018 / Published: 3 April 2018
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Abstract
Although continuous production processes are often desired, many processing industries still work in batch mode due to technical limitations. Transitioning to continuous production requires an in-depth understanding of how each unit operation is affected by the shift. This contribution reviews the scientific understanding
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Although continuous production processes are often desired, many processing industries still work in batch mode due to technical limitations. Transitioning to continuous production requires an in-depth understanding of how each unit operation is affected by the shift. This contribution reviews the scientific understanding of similarities and differences between emulsification in turbulent rotor-stator mixers (also known as high-speed mixers) operated in batch and continuous mode. Rotor-stator mixers are found in many chemical processing industries, and are considered the standard tool for mixing and emulsification of high viscosity products. Since the same rotor-stator heads are often used in both modes of operation, it is sometimes assumed that transitioning from batch to continuous rotor-stator mixers is straight-forward. However, this is not always the case, as has been shown in comparative experimental studies. This review summarizes and critically compares the current understanding of differences between these two operating modes, focusing on shaft power draw, pumping power, efficiency in producing a narrow region of high intensity turbulence, and implications for product quality differences when transitioning from batch to continuous rotor-stator mixers. Full article
(This article belongs to the Special Issue Feature Papers for Celebrating the Fifth Founding Year of Processes)
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Open AccessFeature PaperReview Free-Radical Graft Polymerization onto Starch as a Tool to Tune Properties in Relation to Potential Applications. A Review
Processes 2018, 6(4), 31; https://doi.org/10.3390/pr6040031
Received: 28 February 2018 / Revised: 22 March 2018 / Accepted: 30 March 2018 / Published: 2 April 2018
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Abstract
Grafting of acrylic monomers onto the renewable feedstock starch via free radical polymerizations has been investigated for many years. Many potential applications have been studied, such as superabsorbents, flocculants, thickening agents and so forth. It is expected that size and spacing of the
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Grafting of acrylic monomers onto the renewable feedstock starch via free radical polymerizations has been investigated for many years. Many potential applications have been studied, such as superabsorbents, flocculants, thickening agents and so forth. It is expected that size and spacing of the grafts have a large influence on the performance of such polymers. Yet, information upon the structure-property relationships is only scarcely found in literature. Moreover, there is no clear overview of how reaction variables can be used to influence the grafted structure. In this review, an assessment has been made of the relation between the architecture of the grafts and potential applications. Then, from a selection of relevant literature data it is demonstrated that reaction variables such as the relative concentrations of initiator and monomer, have a large impact on the average size and spacing of the grafts. The emergence of controlled radical polymerizations, like Atom Transfer Radical Polymerization (ATRP) and Reversible Addition-Fragmentation chain Transfer (RAFT), is discussed, both the current status and future prospects. These methods are promising in the future of starch grafting, especially for systems where homopolymer formation may be a problem. Nevertheless, higher costs and other related issues make these advanced methods more suitable in high added-value products. Full article
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Open AccessFeature PaperArticle Genome-Scale In Silico Analysis for Enhanced Production of Succinic Acid in Zymomonas mobilis
Processes 2018, 6(4), 30; https://doi.org/10.3390/pr6040030
Received: 18 January 2018 / Revised: 12 March 2018 / Accepted: 26 March 2018 / Published: 1 April 2018
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Abstract
Presented herein is a model-driven strategy for characterizing the production capability of expression host and subsequently identifying targets for strain improvement by resorting to network structural comparison with reference strain and in silico analysis of genome-scale metabolic model. The applicability of the strategy
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Presented herein is a model-driven strategy for characterizing the production capability of expression host and subsequently identifying targets for strain improvement by resorting to network structural comparison with reference strain and in silico analysis of genome-scale metabolic model. The applicability of the strategy was demonstrated by exploring the capability of Zymomonas mobilis, as a succinic acid producer. Initially, the central metabolism of Z. mobilis was compared with reference producer, Mannheimia succiniciproducens, in order to identify gene deletion targets. It was followed by combinatorial gene deletion analysis. Remarkably, resultant in silico strains suggested that knocking out pdc, ldh, and pfl genes encoding pyruvate-consuming reactions as well as the cl gene leads to fifteen-fold increase in succinic acid molar yield. The current exploratory work could be a promising support to wet experiments by providing guidance for metabolic engineering strategies and lowering the number of trials and errors. Full article
(This article belongs to the Special Issue Biological Networks)
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Open AccessArticle Ball Milling Treatment of Black Dross for Selective Dissolution of Alumina in Sodium Hydroxide Leaching
Processes 2018, 6(4), 29; https://doi.org/10.3390/pr6040029
Received: 27 February 2018 / Revised: 22 March 2018 / Accepted: 23 March 2018 / Published: 25 March 2018
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Abstract
A process consisting of ball milling followed by NaOH leaching was developed to selectively dissolve alumina from black dross. From the ball milling treatment, it was found that milling speed greatly affected the leaching behavior of silica and the oxides of Ca, Fe,
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A process consisting of ball milling followed by NaOH leaching was developed to selectively dissolve alumina from black dross. From the ball milling treatment, it was found that milling speed greatly affected the leaching behavior of silica and the oxides of Ca, Fe, Mg, and Ti present in dross. The leaching behavior of the mechanically activated dross was investigated by varying NaOH concentration, leaching temperature and time, and pulp density. In most of the leaching conditions, only alumina and silica were dissolved, while the leaching percentage of other oxides was negligible. The leaching percentage of silica decreased rapidly to nearly zero as pulp density increased to 100 g/L. At the optimum leaching conditions (5 M NaOH, 50 °C, 2 h, pulp density of 100 g/L), the purity of Al in the leaching solution was higher than 98%, but the leaching percentage of alumina was only 35%. Full article
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Open AccessArticle Steam Explosion and Vibrating Membrane Filtration to Improve the Processing Cost of Microalgae Cell Disruption and Fractionation
Processes 2018, 6(4), 28; https://doi.org/10.3390/pr6040028
Received: 8 February 2018 / Revised: 10 March 2018 / Accepted: 20 March 2018 / Published: 22 March 2018
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Abstract
The aim of this study is to explore an innovative downstream route for microalgae processing to reduce cost production. Experiments have been carried out on cell disruption and fractionation stages to recover lipids, sugars, and proteins. Steam explosion and dynamic membrane filtration were
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The aim of this study is to explore an innovative downstream route for microalgae processing to reduce cost production. Experiments have been carried out on cell disruption and fractionation stages to recover lipids, sugars, and proteins. Steam explosion and dynamic membrane filtration were used as unit operations. The species tested were Nannochloropsis gaditana, Chlorella sorokiniana, and Dunaliella tertiolecta with different cell wall characteristics. Acid-catalysed steam explosion permitted cell disruption, as well as the hydrolysis of carbohydrates and partial hydrolysis of proteins. This permitted a better access to non-polar solvents for lipid extraction. Dynamic filtration was used to moderate the impact of fouling. Filtration enabled two streams: A permeate containing water and monosaccharides and a low-volume retentate containing the lipids and proteins. The necessary volume of solvent to extract the lipids is thus much lower. An estimation of operational costs of both steam explosion and membrane filtration was performed. The results show that the steam explosion operation cost varies between 0.005 $/kg and 0.014 $/kg of microalgae dry sample, depending on the cost of fuel. Membrane filtration cost in fractionation was estimated at 0.12 $/kg of microalgae dry sample. Full article
(This article belongs to the Special Issue Novel Membrane Technologies for Traditional Industrial Processes)
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Open AccessFeature PaperArticle The Impact of Global Sensitivities and Design Measures in Model-Based Optimal Experimental Design
Processes 2018, 6(4), 27; https://doi.org/10.3390/pr6040027
Received: 14 February 2018 / Revised: 15 March 2018 / Accepted: 19 March 2018 / Published: 21 March 2018
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Abstract
In the field of chemical engineering, mathematical models have been proven to be an indispensable tool for process analysis, process design, and condition monitoring. To gain the most benefit from model-based approaches, the implemented mathematical models have to be based on sound principles,
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In the field of chemical engineering, mathematical models have been proven to be an indispensable tool for process analysis, process design, and condition monitoring. To gain the most benefit from model-based approaches, the implemented mathematical models have to be based on sound principles, and they need to be calibrated to the process under study with suitable model parameter estimates. Often, the model parameters identified by experimental data, however, pose severe uncertainties leading to incorrect or biased inferences. This applies in particular in the field of pharmaceutical manufacturing, where usually the measurement data are limited in quantity and quality when analyzing novel active pharmaceutical ingredients. Optimally designed experiments, in turn, aim to increase the quality of the gathered data in the most efficient way. Any improvement in data quality results in more precise parameter estimates and more reliable model candidates. The applied methods for parameter sensitivity analyses and design criteria are crucial for the effectiveness of the optimal experimental design. In this work, different design measures based on global parameter sensitivities are critically compared with state-of-the-art concepts that follow simplifying linearization principles. The efficient implementation of the proposed sensitivity measures is explicitly addressed to be applicable to complex chemical engineering problems of practical relevance. As a case study, the homogeneous synthesis of 3,4-dihydro-1H-1-benzazepine-2,5-dione, a scaffold for the preparation of various protein kinase inhibitors, is analyzed followed by a more complex model of biochemical reactions. In both studies, the model-based optimal experimental design benefits from global parameter sensitivities combined with proper design measures. Full article
(This article belongs to the Special Issue Feature Papers for Celebrating the Fifth Founding Year of Processes)
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Open AccessArticle Assessment of On-Site Treatment Process of Institutional Building’s Wastewater
Processes 2018, 6(4), 26; https://doi.org/10.3390/pr6040026
Received: 12 February 2018 / Revised: 14 March 2018 / Accepted: 17 March 2018 / Published: 21 March 2018
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Abstract
This study is conducted to investigate the characteristics of outflow wastewater of the 1 m3 on-site wastewater treatment unit on the basis of the testing and measurement data of the samples that were taken during the study monitored period (August 2017 to
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This study is conducted to investigate the characteristics of outflow wastewater of the 1 m3 on-site wastewater treatment unit on the basis of the testing and measurement data of the samples that were taken during the study monitored period (August 2017 to January 2018). For this purpose, samples were taken on a weekly basis from the treated wastewater effluent and five quality parameters (biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), pH, E-coli counts) were monitored and measured. The average values of the five parameters were compared with the Jordanian standard maximum values, and water reuse in irrigation of plants classifications have been assessed and investigated. Average values of BOD, COD, TSS, pH, and E-coli in treated wastewater were 11 mg/L, 104 mg/L, 15 mg/L, 7.51, and 387 counts, respectively. The installation of in-line ultraviolet (UV) unit in recirculating delivery system played a vital role in the reduction of counts far below the permissible maximum level (1000 counts). Based on national and international standards and criteria, results showed that the treated wastewater is suitable for the irrigation of two classifications of plants: (i) Fruit trees, road-green sides outside cities, and green landscape; (ii) Crops, commercial crops, and forest trees. Hence, such very low water flow rate treatment system can be utilized in refugees’ camps and water scarce residential areas in Jordan. Full article
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