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ChemEngineering, Volume 5, Issue 4 (December 2021) – 19 articles

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Article
Synthesis and Structural Characterisation of Yttrium-Doped α-Zirconium Phosphate
ChemEngineering 2021, 5(4), 83; https://doi.org/10.3390/chemengineering5040083 (registering DOI) - 02 Dec 2021
Viewed by 137
Abstract
There has been a considerable amount of interest in the ion-exchange properties of layered zirconium phosphates. Potential applications in the remediation of nuclear waste have renewed interest in these inorganic materials, due to their high stability under the acidic conditions typically found in [...] Read more.
There has been a considerable amount of interest in the ion-exchange properties of layered zirconium phosphates. Potential applications in the remediation of nuclear waste have renewed interest in these inorganic materials, due to their high stability under the acidic conditions typically found in legacy waste pools. It has been well documented that the substitution of metals with different ionic radii into the frameworks of inorganic materials can alter the chemical properties including ion-exchange selectivity. The work presented here focusses on the synthesis and characterisation of yttrium-doped α-zirconium phosphates which are reported for the first time. Two different synthetic methods were used, reflux and hydrothermal syntheses, and the products were characterised by various methods such as powdered X-ray diffraction, MAS-NMR and scanning electron microscopy. It was found that up to 15% of zirconium could be replaced by yttrium before any noticeable impurity phases could be observed. Rietveld refinement from the doping showed that the products did not obey the Vegard’s law. However, the ion-exchange results clearly showed enhanced capacities and selectivity towards Co2+ ions for the substituted materials. Full article
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Article
A Framework for Multi-Objective Optimization of Plate-Fin Heat Exchangers Using a Detailed Three-Dimensional Simulation Model
ChemEngineering 2021, 5(4), 82; https://doi.org/10.3390/chemengineering5040082 (registering DOI) - 02 Dec 2021
Viewed by 93
Abstract
The design of a multi-stream plate-fin heat exchanger is a highly integrated task with multiple opposing objectives and many degrees of freedom. This work shows how it can be fully or partially automated by the combination of a detailed three-dimensional simulation model and [...] Read more.
The design of a multi-stream plate-fin heat exchanger is a highly integrated task with multiple opposing objectives and many degrees of freedom. This work shows how it can be fully or partially automated by the combination of a detailed three-dimensional simulation model and an optimization routine. The desired task is formulated as the target of a multi-objective optimization and solved using a genetic algorithm. The workflow is presented using a cryogenic plate-fin heat exchanger with four process streams. The design is optimized towards high efficiency, low pressure drop, and low unit weight by adjusting the outer geometry, the inlet and outlet distributor configuration, and the detailed stream geometry. A detailed analysis of the Pareto-set gives a good overview of possible solutions, and the optimization routine can automatically find a feasible design with a reasonable tradeoff between the objectives. All elements of the framework are implemented in open source software. A highlight of this research is that a very comprehensive and detailed simulation model is employed in the optimization framework. Thus, the presented method can be easily adjusted to fit the needs of other engineering tasks. Full article
(This article belongs to the Special Issue Process Intensification for Chemical Engineering and Processing)
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Article
Life Cycle Assessment of Solid Recovered Fuel Gasification in the State of Qatar
ChemEngineering 2021, 5(4), 81; https://doi.org/10.3390/chemengineering5040081 - 19 Nov 2021
Viewed by 376
Abstract
Gas products from gasified solid recovered fuel (SRF) have been proposed as a replacement for natural gas to produce electricity in future power generation systems. In this work, the life cycle assessment (LCA) of SRF air gasification to energy was conducted using the [...] Read more.
Gas products from gasified solid recovered fuel (SRF) have been proposed as a replacement for natural gas to produce electricity in future power generation systems. In this work, the life cycle assessment (LCA) of SRF air gasification to energy was conducted using the Recipe2016 model considering five environmental impact categories and four scenarios in Qatar. The current situation of municipal solid waste (MSW) handling in Qatar is landfill with composting. The results show that using SRF gasification can reduce the environmental impact of MSW landfills and reliance on natural gas in electricity generation. Using SRF gasification on the selected five environmental impact categories—climate change, terrestrial acidification, marine ecotoxicity, water depletion and fossil resource depletion—returned significant reductions in environmental degradation. The LCA of the SRF gasification for the main four categories in the four scenarios gave varying results. The introduction of the SRF gasification reduced climate change-causing emissions by 41.3% because of production of renewable electricity. A reduction in water depletion and fossil resource depletion of 100 times were achieved. However, the use of solar technology and SRF gasification to generate electricity reduced the impact of climate change to almost zero emissions. Terrestrial acidification showed little to no change in all three scenarios investigated. This study was compared with the previous work from the literature and showed that on a nominal 10 kg MSW processing basis, 5 kg CO2 equivalent emissions were produced for the landfilling scenarios. While the previous studies reported that 8 kg CO2 produced per 10 kg MSW is processed for the same scenario. The findings indicate that introducing SRF gasification in solid waste management and electricity generation in Qatar has the potential to reduce greenhouse gas (GHG) emission load and related social, economic, political and environmental costs. In addition, the adoption of the SRF gasification in the country will contribute to Qatar’s national vision 2030 by reducing landfills and produce sustainable energy. Full article
(This article belongs to the Special Issue Feature Papers in Chemical Engineering)
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Article
Low-Cost Eddy-Resolving Simulation in the Near-Field of an Annular Swirling Jet for Spray Drying Applications
ChemEngineering 2021, 5(4), 80; https://doi.org/10.3390/chemengineering5040080 - 18 Nov 2021
Viewed by 321
Abstract
Spray drying is one of many industrial applications that use annular swirling jets. For this particular application, the flow characteristics in the near-field of the jet are fundamental to obtaining high-quality dried products. In this article, an annular swirling jet configuration is numerically [...] Read more.
Spray drying is one of many industrial applications that use annular swirling jets. For this particular application, the flow characteristics in the near-field of the jet are fundamental to obtaining high-quality dried products. In this article, an annular swirling jet configuration is numerically studied using three low-cost eddy-resolving turbulence methods: detached-eddy simulation (DES), delayed-DES (DDES) and scale-adaptive simulation (SAS). To focus in industrial applicability, very coarse grids are used. The individual performance of these models is assessed through a comparison with laser-Doppler anemometry (LDA) measurements and large-eddy simulation (LES) data from available studies. Results show that all the three turbulence models are suitable for performing industrial cost-effective simulations, capable of reproducing LES results of mean velocities and first-order turbulence statistics at a fraction of the computational cost. Differences in the results of the evaluated models were minor; however, the simulation with DDES still provided a better reproduction of experimental results, especially in the very-near field of the jet, as it enforced RANS behavior near the inlet walls and a better transition from modeled to resolved scales. Full article
(This article belongs to the Special Issue Chemical Engineering and Multidisciplinary)
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Article
A Newly Developed Empirical Predictive Model for the Dispersed Phase (DP) Holdup in Rotating Disc Contactors
ChemEngineering 2021, 5(4), 79; https://doi.org/10.3390/chemengineering5040079 - 15 Nov 2021
Viewed by 304
Abstract
Newly novel developed correlations were derived to predict the dispersed phase (DP) holdup in a rotating disc contactor (RDC) extraction column. DP holdup is one of the significant parameters in the design of liquid–liquid contactors and for calculating their production capacity. Despite the [...] Read more.
Newly novel developed correlations were derived to predict the dispersed phase (DP) holdup in a rotating disc contactor (RDC) extraction column. DP holdup is one of the significant parameters in the design of liquid–liquid contactors and for calculating their production capacity. Despite the availability of quite a large number of holdup prediction correlations for the RDC, most of these correlations are either general in nature or valid for a limited range of operating conditions. This study conducted an experimental and theoretical investigation of the RDC holdup under the influence of varying geometries, including variations in the dispersed phase distributor, speed of the disc, flow rate, and physical characteristics of the system. The analysis revealed that the holdup decreased with an increasing distributor hole diameter and increased with an increasing disc speed and total flow rate. The effect of the physical properties on the holdup was larger than the effect of the disc speed. Using the measurements of over 150 runs, two RDC column holdup predictive models were proposed and evaluated. The first correlation was derived in terms of the distributor hole diameter, operating parameters, system physical properties, and column geometry. The second correlation excluded the column geometry. These correlations, which consider the distributor hole inlet diameter in predicting the DP holdup for an RDC column, were presented for the first time in this study. The predictive capability of these correlations was evaluated via their standard deviation (SD) and mean average percentage error (MAPE). The respective SD and MAPE of the two correlations were 1.7 and 5.2% for the first correlation and 1.6 and 11.4% for the second. Full article
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Review
An Overview of Natural Polymers as Reinforcing Agents for 3D Printing
ChemEngineering 2021, 5(4), 78; https://doi.org/10.3390/chemengineering5040078 - 08 Nov 2021
Viewed by 467
Abstract
Three-dimensional (3D) printing, or additive manufacturing, is a group of innovative technologies that are increasingly employed for the production of 3D objects in different fields, including pharmaceutics, engineering, agri-food and medicines. The most processed materials by 3D printing techniques (e.g., fused deposition modelling, [...] Read more.
Three-dimensional (3D) printing, or additive manufacturing, is a group of innovative technologies that are increasingly employed for the production of 3D objects in different fields, including pharmaceutics, engineering, agri-food and medicines. The most processed materials by 3D printing techniques (e.g., fused deposition modelling, FDM; selective laser sintering, SLS; stereolithography, SLA) are polymeric materials since they offer chemical resistance, are low cost and have easy processability. However, one main drawback of using these materials alone (e.g., polylactic acid, PLA) in the manufacturing process is related to the poor mechanical and tensile properties of the final product. To overcome these limitations, fillers can be added to the polymeric matrix during the manufacturing to act as reinforcing agents. These include inorganic or organic materials such as glass, carbon fibers, silicon, ceramic or metals. One emerging approach is the employment of natural polymers (polysaccharides and proteins) as reinforcing agents, which are extracted from plants or obtained from biomasses or agricultural/industrial wastes. The advantages of using these natural materials as fillers for 3D printing are related to their availability together with the possibility of producing printed specimens with a smaller environmental impact and higher biodegradability. Therefore, they represent a “green option” for 3D printing processing, and many studies have been published in the last year to evaluate their ability to improve the mechanical properties of 3D printed objects. The present review provides an overview of the recent literature regarding natural polymers as reinforcing agents for 3D printing. Full article
(This article belongs to the Special Issue Feature Papers in Chemical Engineering)
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Article
Heavy Metal Accumulation in Soil and Water in Pilot Scale Rice Field Treated with Sewage Sludge
ChemEngineering 2021, 5(4), 77; https://doi.org/10.3390/chemengineering5040077 - 04 Nov 2021
Viewed by 382
Abstract
Widespread use of chemical fertilizers in agricultural activities poses a high risk of multi-micro metal contamination in soils and potentially causes health issues through consumption of contaminated foods. Bio-organic fertilizers from sewage sludge have been regarded as a suitable substitute for chemical fertilizer [...] Read more.
Widespread use of chemical fertilizers in agricultural activities poses a high risk of multi-micro metal contamination in soils and potentially causes health issues through consumption of contaminated foods. Bio-organic fertilizers from sewage sludge have been regarded as a suitable substitute for chemical fertilizer for rice farming. In this study, we investigated accumulation of heavy metals (Cu and Zn) in soil, water and rice plant in three pilot-scale rice paddy fields treated with different fertilization schemes. The control field was treated with conventional chemical fertilizers while the soil of two treatment fields was mixed with biological sewage sludge obtained from a local wastewater treatment system in Vietnam at different ratios (1% and 3%). Initial results showed that heavy metals accumulated in the soil, water, and rice plant at varying levels and most of the Cu and Zn contents found in soils, water and rice products exceeded permissible Vietnamese standards (QCVN 03: 2008) and US EPA 503. Notably, the rice field whose soil was treated with sludge at 3% ratio showed a significantly lower accumulation of heavy metals in soil, water and in rice plant. However, treatment of sludge at this level seemed to cause higher heavy metal retention in soil after one harvest. Semi-quantitative risk analysis revealed that the risk of metal contamination in soil and water of the control field ranged from medium (RQ index between 0.1 and 1) to high risk (RQ index higher than 1) and that fertilization methods would also affect the level of risk to the environment. Full article
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Article
Investigation of Duplex Brass Membranes with Metallography, Permeability and Treatments: Work-Hardening, Annealing and Quenching
ChemEngineering 2021, 5(4), 76; https://doi.org/10.3390/chemengineering5040076 - 03 Nov 2021
Viewed by 325
Abstract
This paper consists of the fabrication and investigation of metal membranes and the study of their behaviour and applications in gas separation processes. The scope is to produce and characterize the porous crystal structure of brass alloy (standardization: DIN 17660) membranes and measure [...] Read more.
This paper consists of the fabrication and investigation of metal membranes and the study of their behaviour and applications in gas separation processes. The scope is to produce and characterize the porous crystal structure of brass alloy (standardization: DIN 17660) membranes and measure their permeability with helium as a penetrant medium. Another part of this study is to alter the brass alloy’s structure throughout metallurgical treatments and investigate how the permeability is allied to the structure’s alteration. This work merges the knowledge and technology of inorganic porous materials science in metallurgy. The novelty of the current research resides in the process to alternate the brass alloy structure throughout metallurgical treatments and how it is allied to the permeability of the membrane, which is of interest to be investigated. The results of the research are analysed and compared conducting the final inferences. All metallurgical treatments resulted in low permeability values when compared to a non-treated specimen. Specifically, the drop in permeance ranged from 76 up to 99.56%. It is noted that consecutive treatments contributed to even further decreases. Full article
(This article belongs to the Special Issue Feature Papers in Chemical Engineering)
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Article
Effects of Constant Electric Field on Biodegradation of Phenol by Free and Immobilized Cells of Bradyrhizobium japonicum 273
ChemEngineering 2021, 5(4), 75; https://doi.org/10.3390/chemengineering5040075 - 02 Nov 2021
Viewed by 247
Abstract
It is shown that bacteria Bradyrhizobium japonicum 273 were capable of degrading phenol at moderate concentrations either in a free cell culture or by immobilized cells on granulated activated carbon particles. The amount of degraded phenol was greater in an immobilized cell preparation [...] Read more.
It is shown that bacteria Bradyrhizobium japonicum 273 were capable of degrading phenol at moderate concentrations either in a free cell culture or by immobilized cells on granulated activated carbon particles. The amount of degraded phenol was greater in an immobilized cell preparation than in a free culture. The application of a constant electric field during cultivation led to enhanced phenol biodegradation in a free culture and in immobilized cells on granulated activated carbon. The highest phenol removal efficiency was observed for an anode potential of 1.0 V/S.H.E. The effect was better pronounced in a free culture. The enzyme activities of free cells for phenol oxidation and benzene ring cleavage were very sensitive to the anode potential in the first two steps of the metabolic pathway of phenol biodegradation catalyzed by phenol hydroxylase—catechol-1,2-dioxygenase and catechol-2,3-dioxygenase. It was observed that at an anode potential of 0.8 V/S.H.E., the meta-pathway of cleavage of the benzene ring catalyzed by catechol-2,3-dioxygenase became competitive with the ortho-pathway, catalyzed by catechol-1,2-dioxygenase. The obtained results showed that the positive effect of constant electric field on phenol biodegradation was rather due to electric stimulation of enzyme activity than electrochemical anode oxidation. Full article
(This article belongs to the Special Issue Feature Papers in Chemical Engineering)
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Review
Cleavage via Selective Catalytic Oxidation of Lignin or Lignin Model Compounds into Functional Chemicals
ChemEngineering 2021, 5(4), 74; https://doi.org/10.3390/chemengineering5040074 - 01 Nov 2021
Viewed by 293
Abstract
Lignin, a complex aromatic polymer with different types of methoxylated phenylpropanoid connections, enables the sustainable supply of value-added chemicals and biofuels through its use as a feedstock. Despite the development of numerous methodologies that upgrade lignin to high-value chemicals such as drugs and [...] Read more.
Lignin, a complex aromatic polymer with different types of methoxylated phenylpropanoid connections, enables the sustainable supply of value-added chemicals and biofuels through its use as a feedstock. Despite the development of numerous methodologies that upgrade lignin to high-value chemicals such as drugs and organic synthesis intermediates, the variety of valuable products obtained from lignin is still very limited, mainly delivering hydrocarbons and oxygenates. Using selective oxidation and activation cleavage of lignin, we can obtain value-added aromatics, including phenols, aldehydes, ketones, and carboxylic acid. However, biorefineries will demand a broad spectrum of fine chemicals in the future, not just simple chemicals like aldehydes and ketones containing simple C = O groups. In particular, most n-containing aromatics, which have found important applications in materials science, agro-chemistry, and medicinal chemistry, such as amide, aniline, and nitrogen heterocyclic compounds, are obtained through n-containing reagents mediating the oxidation cleavage in lignin. This tutorial review provides updates on recent advances in different classes of chemicals from the catalytic oxidation system in lignin depolymerization, which also introduces those functionalized products through a conventional synthesis method. A comparison with traditional synthetic strategies reveals the feasibility of the lignin model and real lignin utilization. Promising applications of functionalized compounds in synthetic transformation, drugs, dyes, and textiles are also discussed. Full article
(This article belongs to the Special Issue Feature Papers in Chemical Engineering)
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Review
Recent Advances on Quinazoline Derivatives: A Potential Bioactive Scaffold in Medicinal Chemistry
ChemEngineering 2021, 5(4), 73; https://doi.org/10.3390/chemengineering5040073 - 26 Oct 2021
Viewed by 513
Abstract
This paper intended to explore and discover recent therapeutic agents in the area of medicinal chemistry for the treatment of various diseases. Heterocyclic compounds represent an important group of biologically active compounds. In the last few years, heterocyclic compounds having quinazoline moiety have [...] Read more.
This paper intended to explore and discover recent therapeutic agents in the area of medicinal chemistry for the treatment of various diseases. Heterocyclic compounds represent an important group of biologically active compounds. In the last few years, heterocyclic compounds having quinazoline moiety have drawn immense attention owing to their significant biological activities. A diverse range of molecules having quinazoline moiety are reported to show a broad range of medicinal activities like antifungal, antiviral, antidiabetic, anticancer, anti-inflammatory, antibacterial, antioxidant and other activities. This study accelerates the designing process to generate a greater number of biologically active candidates. Full article
(This article belongs to the Special Issue Feature Papers in Chemical Engineering)
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Article
Increasing the Adherence of Metallic Copper to the Surface of Titanium Hydride
ChemEngineering 2021, 5(4), 72; https://doi.org/10.3390/chemengineering5040072 - 25 Oct 2021
Viewed by 315
Abstract
Studies have been carried out to increase the adhesive interaction between a titanium hydride substrate and a copper coating. An additional layer containing chemically active groups was created on the surface of the spherical titanium hydride by chemisorption modification. This paper discusses the [...] Read more.
Studies have been carried out to increase the adhesive interaction between a titanium hydride substrate and a copper coating. An additional layer containing chemically active groups was created on the surface of the spherical titanium hydride by chemisorption modification. This paper discusses the results of scanning electron microscopy (SEM) using energy-dispersive X-ray spectroscopic mapping of coatings obtained on spherical granules of titanium hydride before and after adsorption modification. The mechanism of interaction of the surface of spherical granules of titanium hydride and titanium sulfate salt is proposed. It is shown that the creation of a chemisorbed layer of hydroxotitanyl and the subsequent electrodeposition of metallic copper contribute to the formation of a multilayer shell of a titanium–copper coating on the surface of spherical titanium hydride granules (≡Ti-O-Cu-) with a high adhesive interaction. Results have been given for an experimental study of the thermal stability of the initial spherical granules of titanium hydride and granules coated with a multilayer titanium-copper shell. Full article
(This article belongs to the Special Issue Chemical Engineering and Multidisciplinary)
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Article
Amino Ethers of Ortho-Phosphoric Acid as Extragents for Ethanol Dehydration
ChemEngineering 2021, 5(4), 71; https://doi.org/10.3390/chemengineering5040071 - 21 Oct 2021
Viewed by 333
Abstract
Amino ethers of ortho-phosphoric acid prepared using triethanolamine; ortho-phosphoric acid; polyoxyethylene glycol, diethylene glycol, triethylene glycol and glycerol (AEPA-DEG/TEG/Gl) were investigated as extractants for the separation of aqueous ethanol solutions by extractive distillation. Using the method of open evaporation, the influence [...] Read more.
Amino ethers of ortho-phosphoric acid prepared using triethanolamine; ortho-phosphoric acid; polyoxyethylene glycol, diethylene glycol, triethylene glycol and glycerol (AEPA-DEG/TEG/Gl) were investigated as extractants for the separation of aqueous ethanol solutions by extractive distillation. Using the method of open evaporation, the influence of the molecular structure of AEPA-DEG/TEG/Gl on the conditions of vapor–liquid equilibrium in ethanol–water solutions was studied. It has been shown that the addition of AEPA-DEG/TEG/Gl removes the azeotropic point. At the same time, the observed effect turned out to be significantly higher in comparison with the use of pure glycerol or glycols for these purposes. The UNIFAC model was used to calculate the activity coefficients in a three-component ethanol–water–AEPA-DEG/TEG/Gl mixture. Within the framework of this model, a division of AEPA-DEG/TEG/Gl molecules into group components is proposed. Previously unknown parameters of the groups PO–CH, PO–CH2, PO–OCH2, PO–NHCH2, PO–OH, and PO–H2O were determined from our own and published experimental data. The concentration dependences of the density and dynamic viscosity of AEPA-Gl aqueous solutions have been experimentally measured. Experimental studies of the extractive distillation of ethanol–water using AEPA-Gl as an extractant have been carried out in a column with bubble cap plates and a packing, and its high efficiency has been established. Full article
(This article belongs to the Special Issue Feature Papers in Chemical Engineering)
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Article
Methanol–Water Purification Control Using Multi-Loop PI Controllers Based on Linear Set Point and Disturbance Models
ChemEngineering 2021, 5(4), 70; https://doi.org/10.3390/chemengineering5040070 - 20 Oct 2021
Viewed by 416
Abstract
Dimethyl ether (DME), derived from methanol, has been issued as an alternative to diesel and LPG. This study will continue the research of an optimized process control design for DME purification plants, specifically the methanol purification process. This way, water can be separated, [...] Read more.
Dimethyl ether (DME), derived from methanol, has been issued as an alternative to diesel and LPG. This study will continue the research of an optimized process control design for DME purification plants, specifically the methanol purification process. This way, water can be separated, and the main product, methanol, can be recycled for DME synthesis. A setpoint-based linear model of a methanol–water purification system has been developed with four controlled variables (CV) with objectives to; maintain a separated liquid water stream in the bottom stage (Stage 30) of the distillation column for methanol–water separation at 11.22%, keep the purified liquid methanol at a condenser at 58.81 °C and 49.96% of level, and the last CV is the cooler in the distillate stream, to keep the purified methanol’s top product at 40.75 °C. To complete the model, a first order plus dead time (FOPDT) disturbance model is created against the inlet temperature and flow rate of the feed, the major cause of disturbances in the industry. Using a traditional proportional integral controller connected to each controlled variable, a multi-loop control system is formed with optimization and compared to the disturbance rejection of multivariable model predictive control (MMPC). The final improvement against the feed temperature and flow for CV1, CV2, CV3, and CV4 is shown by, respectively, Integral Absolute Error (IAE) values of 79.49%, 99.90%, 100%, and 99.99% and Integral Square Error (ISE) values of 97.1%, 100%, 99.99%, and 100%. Full article
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Review
Application of Gold Nanoparticle-Based Materials in Cancer Therapy and Diagnostics
ChemEngineering 2021, 5(4), 69; https://doi.org/10.3390/chemengineering5040069 - 16 Oct 2021
Cited by 1 | Viewed by 551
Abstract
Several metal nanoparticles have been developed for medical application. While all have their benefits, gold nanoparticles (AuNPs) are ideal in cancer therapy and diagnosis as they are chemically inert and minimally toxic. Several studies have shown the potential of AuNPs in the therapeutic [...] Read more.
Several metal nanoparticles have been developed for medical application. While all have their benefits, gold nanoparticles (AuNPs) are ideal in cancer therapy and diagnosis as they are chemically inert and minimally toxic. Several studies have shown the potential of AuNPs in the therapeutic field, as photosensitizing agents in sonochemical and photothermal therapy and as drug delivery, as well as in diagnostics and theranostics. Although there is a significant number of reviews on the application of AuNPs in cancer medicine, there is no comprehensive review on their application both in therapy and diagnostics. Therefore, considering the high number of studies on AuNPs’ applications, this review summarizes data on the application of AuNPs in cancer therapy and diagnostics. In addition, we looked at the influence of AuNPs’ shape and size on their biological properties. We also present the potential use of hybrid materials based on AuNPs in sonochemical and photothermal therapy and the possibility of their use in diagnostics. Despite their potential, the use of AuNPs and derivatives in cancer medicine still has some limitations. In this review, we provide an overview of the biological, physicochemical, and legal constraints on using AuNPs in cancer medicine. Full article
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Article
Kinetics of Simultaneous Ammonium and Phosphate Recovery by Natural Zeolite
ChemEngineering 2021, 5(4), 68; https://doi.org/10.3390/chemengineering5040068 - 08 Oct 2021
Viewed by 371
Abstract
Nowadays, fertilizers containing nitrogen and phosphorus are indispensable for medium and large-scale industrial agriculture. To meet the growing demand of nutrients and reduce the accompanied ecological footprint of primary fertilizer production, processes and technologies for nutrient recovery are necessary and have to be [...] Read more.
Nowadays, fertilizers containing nitrogen and phosphorus are indispensable for medium and large-scale industrial agriculture. To meet the growing demand of nutrients and reduce the accompanied ecological footprint of primary fertilizer production, processes and technologies for nutrient recovery are necessary and have to be developed. This study represents the basis of an extension of the ion-exchange-loop-stripping process (ILS), which is a combined stripping and ion exchange process using natural zeolite for nitrogen recovery. In batch experiments with a special zeolite filled stirrer, the mechanism and kinetics of simultaneous ammonium and phosphate recovery by natural zeolite were determined. Zeolite loadings of 6.78 mg PO43− g−1 were reached and after regeneration, phosphate recovery rates up to 75% of the initial concentration were achieved. The speed of phosphate precipitation is mostly controlled by the pH value of synthetic wastewater. Phosphate removal in simultaneous experiments does not affect ammonium sorption onto zeolite. These findings and the different removal mechanisms of ammonium and phosphate lead to versatile applications in wastewater treatment and reveal great potential of natural zeolite in simultaneous nutrient recovery processes. Full article
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Perspective
Space and Time Crystal Engineering in Developing Futuristic Chemical Technology
ChemEngineering 2021, 5(4), 67; https://doi.org/10.3390/chemengineering5040067 - 07 Oct 2021
Viewed by 457
Abstract
In the coming years, multipurpose catalysts for delivering different products under the same chemical condition will be required for developing smart devices for industrial or household use. In order to design such multipurpose devices with two or more specific roles, we need to [...] Read more.
In the coming years, multipurpose catalysts for delivering different products under the same chemical condition will be required for developing smart devices for industrial or household use. In order to design such multipurpose devices with two or more specific roles, we need to incorporate a few independent but externally controllable catalytically active centers. Through space crystal engineering, such an externally controllable multipurpose MOF-based photocatalyst could be designed. In a chemical system, a few mutually independent secondary reaction cycles nested within the principal reaction cycle can be activated externally to yield different competitive products. Each reaction cycle can be converted into a time crystal, where the time consuming each reaction step could be converted as an event and all the reaction steps or events could be connected by a circle to build a time crystal. For fractal reaction cycles, a time polycrystal can be generated. By activating a certain fractal event based nested time crystal branch, we can select one of the desired competitive products according to our needs. This viewpoint intends to bring together the ideas of (spatial) crystal engineering and time crystal engineering in order to make use of the time–space arrangement in reaction–catalysis systems and introduce new aspects to futuristic chemical engineering technology. Full article
(This article belongs to the Special Issue Green Photocatalysts for Energy and Environmental Process)
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Article
Development of a Dynamic Modeling Approach to Simulate a Segmented Distillation Column for Flexible Operation
ChemEngineering 2021, 5(4), 66; https://doi.org/10.3390/chemengineering5040066 - 01 Oct 2021
Viewed by 468
Abstract
The need for flexible process equipment has increased over the past decade in the chemical industry. However, process equipment such as distillation columns have limitations that significantly restrict flexible operation. We investigate a segmented tray column designed to allow flexible operation. The design [...] Read more.
The need for flexible process equipment has increased over the past decade in the chemical industry. However, process equipment such as distillation columns have limitations that significantly restrict flexible operation. We investigate a segmented tray column designed to allow flexible operation. The design consists of radial trays connected at the downcomer of each tray. Each segment can be operated separately, but depending on the capacity of the feed stream, additional segments can be activated or deactivated. The connection between the trays aims to transfer liquid from one stationary segment to the adjacent inactive segment, thereby reducing the time required for the start-up process. In a case study on the separation of methanol and water, we perform dynamic simulations to assess the reduction in the start-up time of inactive segments. The results confirm the advantages over standard tray designs. The segmented distillation column is a step towards improving the flexibility of separation operations. Full article
(This article belongs to the Special Issue Feature Papers in Chemical Engineering)
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Article
Comparison of the Fluidized State Stability from Radioactive Particle Tracking Results
ChemEngineering 2021, 5(4), 65; https://doi.org/10.3390/chemengineering5040065 - 01 Oct 2021
Viewed by 401
Abstract
Currently, various industrial processes are carried out in fluidized bed reactors. Knowing its internal dynamics is fundamental for the intensification of these processes. This work assesses the motion of fluidized calcium alginate spheres under the influence of an upward fluid flow within a [...] Read more.
Currently, various industrial processes are carried out in fluidized bed reactors. Knowing its internal dynamics is fundamental for the intensification of these processes. This work assesses the motion of fluidized calcium alginate spheres under the influence of an upward fluid flow within a 1.2 m high and 0.1 m inner diameter acrylic column. The liquid–solid fluidized bed was compared with a gas–liquid–solid fluidized bed operation mode in terms of mixing behavior. The radioactive particle tracking technique is a proper methodology to study the internal dynamics of these kinds of equipment. Data gathered were analyzed with Shannon entropy as a dynamic mixing measure. Mixing times were found to be between 1 and 2.5 seconds for both fluidization modes. The liquid–solid fluidized bed presents a rather smooth mixing time profile along the column. On the other hand, the gas–liquid–solid fluidized bed showed high sensitivity of entropy production with height, reaching a sharp tendency break at the second quartile of the column. The Glansdorff–Prigogine stability measure can accurately capture flow regime transitions of the gas–liquid–solid fluidized bed, allowing it to be used to construct reliable operative windows for fluidization equipment. Full article
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