Journal Description
ChemEngineering
ChemEngineering
is an international, peer-reviewed, open access journal on the science and technology of chemical engineering, published bimonthly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, ESCI (Web of Science), Inspec, CAPlus / SciFinder, and other databases.
- Journal Rank: CiteScore - Q1 (General Engineering)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 21.5 days after submission; acceptance to publication is undertaken in 7.8 days (median values for papers published in this journal in the first half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
Impact Factor:
2.5 (2022);
5-Year Impact Factor:
2.7 (2022)
Latest Articles
Low-Waste Synthesis and Properties of Highly Dispersed NiO·Al2O3 Mixed Oxides Based on the Products of Centrifugal Thermal Activation of Gibbsite
ChemEngineering 2023, 7(4), 71; https://doi.org/10.3390/chemengineering7040071 - 29 Jul 2023
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This study revealed an increased reactivity of centrifugally thermoactivated products of gibbsite toward aqueous solutions of nickel nitrate at room temperature as well as under hydrothermal conditions. X-ray, thermal, microscopy, adsorption and chemical analysis methods were used to investigate and demonstrate the possibility
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This study revealed an increased reactivity of centrifugally thermoactivated products of gibbsite toward aqueous solutions of nickel nitrate at room temperature as well as under hydrothermal conditions. X-ray, thermal, microscopy, adsorption and chemical analysis methods were used to investigate and demonstrate the possibility of obtaining highly loaded mixed aluminum–nickel oxide systems, with a nickel content of ca. 33 wt.%, using a hydrochemical treatment at room temperature or a hydrothermal treatment of suspensions of the product of the centrifugal thermal activation of gibbsite in aqueous solutions of nickel nitrate. It was shown that the thermal treatment of xerogels—hydrochemical interaction products—in the range of 350–850 °C led to the formation of NiO phases and highly dispersed solid solutions of nickel based on the NiAl2O4 spinel structure, with different ratios and a high specific surface area of 140–200 m2/g. A hydrochemical treatment of suspensions at room temperature ensures that the predominant formation of the NiO phase is distributed over the surface of the alumina matrix after calcination, whereas hydrothermal treatment at 150 °C leads to a deeper interaction of the suspension components at the treatment step, which occurs after the thermal treatment of the formed xerogel in the predominant formation of poorly crystallized NiAl2O4 spinel (“protospinel”). The considered method makes it possible to obtain complex aluminum–nickel oxide systems with different phase ratios, decreases the number of initial reagents and synthesis steps, completely excludes waste and diminishes the total amount of nitrates by 75 wt.% compared to the classical nitrate scheme for the coprecipitation of compounds with a similar elemental composition.
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Recent Progress in the Viscosity Modeling of Concentrated Suspensions of Unimodal Hard Spheres
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ChemEngineering 2023, 7(4), 70; https://doi.org/10.3390/chemengineering7040070 - 27 Jul 2023
Abstract
The viscosity models for concentrated suspensions of unimodal hard spheres published in the twenty-first century are reviewed, compared, and evaluated using a large pool of available experimental data. The Pal viscosity model for unimodal suspensions is the best available model in that the
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The viscosity models for concentrated suspensions of unimodal hard spheres published in the twenty-first century are reviewed, compared, and evaluated using a large pool of available experimental data. The Pal viscosity model for unimodal suspensions is the best available model in that the predictions of this model agree very well with the low (zero)-shear experimental relative viscosity data for coarse suspensions, nanosuspensions, and coarse suspensions thickened by starch nanoparticles. The average percentage error in model predictions is less than 6.5%. Finally, the viscous behavior of concentrated multimodal suspensions is simulated using the Pal model for unimodal suspensions.
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(This article belongs to the Special Issue Exclusive Collection: Papers from the Editorial Board Members (EBMs) of ChemEngineering)
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Hydraulic Cold-Pressed Extraction of Sacha Inchi Seeds: Oil Yield and Its Physicochemical Properties
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, , , , , and
ChemEngineering 2023, 7(4), 69; https://doi.org/10.3390/chemengineering7040069 - 27 Jul 2023
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Sacha inchi oil (SIO) extraction has been extensively studied using various oil extraction techniques to achieve a high oil recovery. However, most studies relied on heat-based methods, which led to compromised oil quality and reduced nutritional values, particularly polyunsaturated fatty acids (omega-3 and
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Sacha inchi oil (SIO) extraction has been extensively studied using various oil extraction techniques to achieve a high oil recovery. However, most studies relied on heat-based methods, which led to compromised oil quality and reduced nutritional values, particularly polyunsaturated fatty acids (omega-3 and omega-6), vitamin E, and phenolic compounds. To address these concerns, this study employed a hydraulic cold-pressed extraction (HCPE) technique for extracting SIO aiming to enhance oil yield while preserving its nutritional integrity. During the HCPE process of sacha inchi seeds (SIS), conducted at a constant temperature of 25 ± 1 °C, pressures and pressing times were varied within the range of 30–50 MPa and 10–30 min, respectively, to determine their impact on SIO yields. The results revealed that both pressure and pressing time significantly influenced the yields of SIO (p < 0.05), with the highest oil recovery of 86.31 wt.% on a wet basis achieved at 50 MPa for 30 min. Regarding physicochemical properties, the peroxide values (5.71–9.07 meq/kg), iodine values (176.22–197.76 g I2/100 g), acid values (1.82–2.16 mg KOH/g), and percentage of free fatty acids (0.91–1.08 wt.% as oleic acid) were found to be influenced by pressure and pressing time (p < 0.05). Additionally, the color variation by L* (34.22–35.17), −a* (0.39–0.81), and b* (3.48–5.62) changed with each oil yield. Notably, the high iodine value in SIO indicated a substantial content of polyunsaturated fatty acids, including omega-3 (40.86%), omega-6 (40.87%), and omega-9 (10.20%). Furthermore, a comparison with solvent extraction methods demonstrated that HCPE exhibited similar efficiency in extracting SIO, offering additional advantage in terms of its cold-pressed condition, eliminating of solvent use, simplicity, short extraction time, and higher oil recovery.
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Open AccessArticle
Experimental Investigation of Heat Losses in a Pilot-Scale Multiple Dividing Wall Distillation Column with Three Parallel Sections
ChemEngineering 2023, 7(4), 68; https://doi.org/10.3390/chemengineering7040068 - 26 Jul 2023
Abstract
For an in-depth investigation of the separation process in small-scale distillation columns, knowledge about the exact vapor load inside the column is highly important. However, since columns with small diameters have a comparatively high surface-to-volume ratio, heat losses have a significant impact on
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For an in-depth investigation of the separation process in small-scale distillation columns, knowledge about the exact vapor load inside the column is highly important. However, since columns with small diameters have a comparatively high surface-to-volume ratio, heat losses have a significant impact on fluid dynamics, as they lead to unwanted condensation, and thus, to changes in the internal flows. This work presents a procedure used to measure heat losses in a 9.6 m high distillation column with three partially parallel segments (multiple dividing wall column). The evaporator is made of stainless steel, and the column walls are made of double-walled, evacuated, mirrored glass, and additionally, these can be heated. It is found that significant amounts of heat are lost in the evaporator. Throughout the column height, around 0.8 kW are additionally lost, even with external wall heating. To determine the main reason for this significant loss, thermal images are taken, indicating that the problem mainly arises because of the flanges. Based on this, it can be concluded that proper insulation and additional heating jackets for the column walls are highly recommended for small-scale distillation columns in order to increase their thermal efficiency.
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(This article belongs to the Special Issue Process Intensification for Chemical Engineering and Processing)
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Influence of the Absolute Pressure of the Extraction System on the Yield and Composition of Corymbia citriodora (Hook.) K.D.Hill and L.A.S.Johnson Leaf Essential Oil Extracted by Steam Distillation
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, , and
ChemEngineering 2023, 7(4), 67; https://doi.org/10.3390/chemengineering7040067 - 24 Jul 2023
Abstract
This study aimed to evaluate the extraction of Corymbia citriodora (Hook.) K.D.Hill and L.A.S.Johnson essential oil by steam distillation under reduced pressure. Yield and composition of the essential oils obtained at different system pressures were analyzed. System pressure had a significant influence on
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This study aimed to evaluate the extraction of Corymbia citriodora (Hook.) K.D.Hill and L.A.S.Johnson essential oil by steam distillation under reduced pressure. Yield and composition of the essential oils obtained at different system pressures were analyzed. System pressure had a significant influence on essential oil yield, resulting in a reduction of 78.6% when the pressure was reduced from 690 Torr to 240 Torr. There were also changes in essential oil composition, with an increase in citronellol content (oxygenated monoterpene). However, the major compound (citronellal) remained at a high content in all tests. Regarding the extracted mass of the major compounds (citronellal, citronellol), there was a significant reduction for all when the system pressure was reduced. Although the reduction in the pressure of the system caused a reduction in oil yield, it was possible to carry out the steps of extraction and purification of the major compound simultaneously. Reduced pressure extraction may decrease process time, increasing its efficiency and reducing costs in the extraction of essential oils.
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(This article belongs to the Special Issue Green and Environmentally Sustainable Chemical Processes)
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Open AccessReview
Functional Nanostructured Materials in the Cosmetics Industry: A Review
ChemEngineering 2023, 7(4), 66; https://doi.org/10.3390/chemengineering7040066 - 21 Jul 2023
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Cosmetics have always been in demand across the globe among people of all age groups. In the modern cosmetic world, nanostructured materials have proven hugely advantageous in producing cosmeceuticals or ‘nano-cosmeceuticals’ and various beauty products. The application of nanostructured materials in cosmetic products
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Cosmetics have always been in demand across the globe among people of all age groups. In the modern cosmetic world, nanostructured materials have proven hugely advantageous in producing cosmeceuticals or ‘nano-cosmeceuticals’ and various beauty products. The application of nanostructured materials in cosmetic products possesses some challenges in terms of short- and long-term safety and environmental issues, despite their growing popularity. The nanostructured particles in cosmeceuticals provide a targeted route of administration due to their high penetrability, site selectivity, high effectiveness, prolonged activity, and drug encapsulation potential. However, standard methods for toxicity evaluation may not be relevant for cosmeceuticals, leading to the need for an alternative methodology. This review article compiles detailed descriptions of all significant aspects of nanostructured materials in the cosmetics industry, which include the synthesis and characterization of relevant nanostructured materials for cosmeceuticals, state-of-the-art practices, mechanisms for the synthesis of advanced materials, toxicological concerns in terms of health risks in humans, and environmental concerns. Also, a proposal for new approaches in terms of regulatory measures to mitigate these problems has been suggested. The primary focus of this article is to provide a comprehensive outlook on this subject area and contribute to the exploration of new prospects and emerging roles of nanostructured materials in the cosmetics industry.
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Open AccessArticle
Process Optimization of Biodiesel from Used Cooking Oil in a Microwave Reactor: A Case of Machine Learning and Box–Behnken Design
ChemEngineering 2023, 7(4), 65; https://doi.org/10.3390/chemengineering7040065 - 21 Jul 2023
Abstract
In the present investigation, response surface methodology (RSM) and machine learning (ML) are applied to the biodiesel production process via acid-catalyzed transesterification and esterification of triglyceride (TG). In order to optimize the production of biodiesel from used cooking oil (UCO) in a microwave
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In the present investigation, response surface methodology (RSM) and machine learning (ML) are applied to the biodiesel production process via acid-catalyzed transesterification and esterification of triglyceride (TG). In order to optimize the production of biodiesel from used cooking oil (UCO) in a microwave reactor, these models are also compared. During the process, Box–Behnken design (BBD) and an artificial neural network (ANN) were used to evaluate the effect of the catalyst content (3.0–7.0 wt.%), methanol/UCO mole ratio (12:1–18:1), and irradiation time (5.0–9.0 min). The process conditions were adjusted and developed to predict the highest biodiesel yield using BBD with the RSM approach and an ANN model. With optimal process parameters of 4.94 wt.% catalyst content, 16.76:1 methanol/UCO mole ratio, and 8.13 min of irradiation time, a yield of approximately 98.62% was discovered. The coefficient of determination (R2) for the BBD model was found to be 0.9988, and the correlation coefficient (R) for the ANN model was found to be 0.9994. According to the findings, applying RSM and ANN models is advantageous when optimizing the biodiesel manufacturing process as well as making predictions about it. This renewable and environmentally friendly process has the potential to provide a sustainable route for the synthesis of high-quality biodiesel from waste oil with a low cost and high acid value.
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(This article belongs to the Special Issue Catalytic Reactions and Development of (Bio)Chemical Processes for Synthesizing Value Added Compounds)
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Development of Mosquito-Repellent Camouflage Fabric Using Eucalyptus Oil with Moringa oleifera Gum
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, , , , , and
ChemEngineering 2023, 7(4), 64; https://doi.org/10.3390/chemengineering7040064 - 20 Jul 2023
Abstract
Military personnel are exposed to several harsh conditions and mosquitos in mountains and wild forests. Mosquito-repellent textiles can help them to cope with such conditions. The present research work established a sustainable approach for fabricating microcapsules from Eucalyptus oil, Moringa oleifera, and
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Military personnel are exposed to several harsh conditions and mosquitos in mountains and wild forests. Mosquito-repellent textiles can help them to cope with such conditions. The present research work established a sustainable approach for fabricating microcapsules from Eucalyptus oil, Moringa oleifera, and Arabic gum via a complex coacervation method. Moringa oleifera and Arabic gums were utilized as the outer shell of the microcapsules, whereas the core part was made of Eucalyptus oil in different concentrations. The military camouflage-printed polyester/cotton (PC) blended fabric was coated with the as-prepared microcapsules using the pad–dry–cure technique. The surface morphology of the microcapsules was examined using an optical microscope and scanning electron microscope (SEM), and the coated fabric’s mosquito-repellent property was investigated using a specified cage test according to a standard testing protocol. The water absorbency and air permeability of the treated samples were also evaluated in order to learn about the comfort properties. The cage test results revealed that the coated fabric had a good tendency to repel the mosquitoes used in the cage test. In addition, the coated fabric showed significant durability even after several rigorous washing cycles. However, the application of microcapsules to the fabric slightly affected the water absorbency and air permeability of the fabric. This study presents a novel sustainable approach for fabricating microcapsules from the mentioned precursors and their application in the field of textiles, particularly for military purposes.
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(This article belongs to the Special Issue Green and Environmentally Sustainable Chemical Processes)
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Evaluation of Jet Flooding in Distillation Column Olefins Plant on Naphtha to LPG Feed Substitution
ChemEngineering 2023, 7(4), 63; https://doi.org/10.3390/chemengineering7040063 - 20 Jul 2023
Abstract
The naphtha cracking process is the most commonly used technology for the production of ethylene, propylene, mixed C4s (including 1,3-butadiene and other C4 components), and pygas (pyrolysis gasoline, a mixture of benzene, toluene, and xylene), all of which are olefins. The cracking
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The naphtha cracking process is the most commonly used technology for the production of ethylene, propylene, mixed C4s (including 1,3-butadiene and other C4 components), and pygas (pyrolysis gasoline, a mixture of benzene, toluene, and xylene), all of which are olefins. The cracking furnace and distillation columns are the primary operational units. The raw material is cracked and undergoes reactions in the cracking furnaces, while the distillation columns are responsible for separating the products. Raw material costs account for 80% of production costs. There is also the possibility of using LPG as a less expensive alternative to some of the naphtha. However, changing the raw material would affect the operability of the distillation columns and influence the yield on the cracking side. To determine the optimal naphtha substitution for LPG without causing hydraulic problems (such as jet flooding) in the distillation columns, analysis using simulation tools must be conducted. A reliability model is being developed to simulate the substitution of naphtha with other feed stocks by comparing simulation results with data from the actual plant. The LPG flow is a variable that is freely adjusted to substitute for naphtha. Simulation tools can be used to assess the effects of economically advantageous naphtha substitution for LPG without compromising plant operability. The optimum naphtha substitution rate is 21.14% from the base case, resulting in jet flooding occurring at Propylene Fractionator No. 2. By implementing this substitution, the benefits that can be obtained amount to USD 22,772.02 per hour.
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(This article belongs to the Special Issue Process Intensification for Chemical Engineering and Processing)
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Using the Response Surface Methodology to Treat Tannery Wastewater with the Bicarbonate-Peroxide System
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ChemEngineering 2023, 7(4), 62; https://doi.org/10.3390/chemengineering7040062 - 16 Jul 2023
Abstract
A bicarbonate-peroxide (BAP) system was evaluated to improve the quality of industrial tannery wastewater using an I-optimal experimental design with four variables (temperature, initial pH, bicarbonate, and H2O2 concentration). The response variables were COD removal, ammonia nitrogen removal, and nitrate
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A bicarbonate-peroxide (BAP) system was evaluated to improve the quality of industrial tannery wastewater using an I-optimal experimental design with four variables (temperature, initial pH, bicarbonate, and H2O2 concentration). The response variables were COD removal, ammonia nitrogen removal, and nitrate concentration. The most critical variables were optimized using a The process was carried out in 500 mL reactors, the operational volume of 250 mL, and the agitation was at 550 rpm. A new I-optimal reaction surface design at two levels (bicarbonate concentration 0.01–0.3 mol/L and H2O2 0.05–0.35 mol/L) was used to obtain the optimal data of the experimental design. Optimal conditions were validated by one-way ANOVA statistical analysis using Prism software. Temperatures above 50 °C promote the efficiency of the BAP system, and slightly acidic initial pHs allow stabilization of the system upon inclusion of bicarbonate and peroxide in the concentration of bicarbonate, which is critical for the reaction with peroxide and formation of reactive oxygen species. With the validated optimal data, removal percentages above 78% were achieved for nitrites, ammonia nitrogen, chromium, TSS, BOD, conductivity, chromium, and chlorides; for COD and TOC, removal percentages were above 45%, these results being equal and even higher than other AOPs implemented for this type of water.
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(This article belongs to the Special Issue Chemical Engineering in Wastewater Treatment)
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Innovations in Modern Nanotechnology for the Sustainable Production of Agriculture
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ChemEngineering 2023, 7(4), 61; https://doi.org/10.3390/chemengineering7040061 - 12 Jul 2023
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Nanotechnology has an extensive series of applications in agronomy and has an important role in the future of sustainable agriculture. The agricultural industries should be supported by innovative active materials such as nanofertilizers, nanofungicides, and nanopesticides. It is necessary in the current situation
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Nanotechnology has an extensive series of applications in agronomy and has an important role in the future of sustainable agriculture. The agricultural industries should be supported by innovative active materials such as nanofertilizers, nanofungicides, and nanopesticides. It is necessary in the current situation to meet the dietary needs of the constantly expanding world population. Nearly one-third of crops grown conventionally suffer damage, mostly as a result of pest infestation, microbiological assaults, natural disasters, poor soil quality, and a lack of nutrients. To solve these problems, we urgently need more inventive technology. The application of nanotechnology in agriculture provides intelligent methods for delivering nutrients, herbicides, and genetic materials for improving soil fertility, stress tolerance, and protection. The world is currently confronting significant issues related to the rising demand for enough food and safe food as well as dealing with the environmental damage caused by traditional agriculture. Nanomaterials have important applications in agriculture for increasing plant growth and development and the quality and quantity of the crops and controlling and managing agricultural diseases. The major objective of this article is to describe the various applications and importance of nanoparticles in the agriculture sector.
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Open AccessArticle
Numerical Study of CO2 Removal from Inhalational Anesthesia System by Using Gas-Ionic Liquid Membrane
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ChemEngineering 2023, 7(4), 60; https://doi.org/10.3390/chemengineering7040060 - 12 Jul 2023
Abstract
Inhalational anesthesia is supplied through an assisted ventilation system. It is mostly composed of xenon or nitrous oxide, halogenated hydrocarbons (HHCs), and oxygen. In order to reduce costs of the anesthesia compounds, the remaining anesthetics present in exhalation are recycled and reused, in
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Inhalational anesthesia is supplied through an assisted ventilation system. It is mostly composed of xenon or nitrous oxide, halogenated hydrocarbons (HHCs), and oxygen. In order to reduce costs of the anesthesia compounds, the remaining anesthetics present in exhalation are recycled and reused, in order to minimize the amount of fresh anesthesia. An alkali hydroxide mixture (called soda lime) is employed in order to remove CO2 from the exhalation. However toxic compounds may be formed during the reaction of soda lime with halogenated hydrocarbons. Ionic liquids (ILs) have several advantages such as non-volatility, functionality, high carbon solubility, and low energy requirements for regeneration. In the framework of this research, carbon dioxide removal with ionic liquids has been numerically studied. COMSOL multi-physics finite element software has been applied. It solves the continuity, fluid flow, and diffusion equations. A new algorithm has been developed for calculating the infrared (IR) radiation absorption of CO2. Its absorption coefficient has wavelength-dependent properties. The gaseous absorption coefficient has been calculated by using HITRAN spectral database. It has been found that the CO2 is absorbed almost completely by the 1-ethyl-3-methylimidazolium dicyanamide ([emim][DCA]) ionic liquid after a period of 1000 s. It has been shown that the absorption coefficient of CO2 can be neglected in the interval below 1.565 μm, and then at 1.6 μm, it increases to the same order as that for CO. Thus, it is possible to detect CO2 by applying a laser diode which is capable to transmit IR radiation at a wavelength of 1.6 μm. This time period is a function of the diffusion coefficient of the CO2 in the membrane and in the ionic liquid.
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(This article belongs to the Special Issue The Applications of Computational Fluid Dynamics in Transport Phenomena)
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One-Dimensional Modeling of Mass Transfer Processes in an Annular Centrifugal Contactor
ChemEngineering 2023, 7(4), 59; https://doi.org/10.3390/chemengineering7040059 - 12 Jul 2023
Abstract
Due to the importance of process intensification, modeling of Annular Centrifugal Contactors (ACCs) is becoming of increasing interest. By the current state of scientific knowledge, universal modeling without high computing power of these complex apparatuses is not possible to a satisfactory degree. In
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Due to the importance of process intensification, modeling of Annular Centrifugal Contactors (ACCs) is becoming of increasing interest. By the current state of scientific knowledge, universal modeling without high computing power of these complex apparatuses is not possible to a satisfactory degree. In this article, a one-dimensional model to describe the mass transfer during a physical extraction process in an ACC is presented. The model is based on solely geometrical data and operating conditions of the ACC, as well as physical properties of the components. Regarding the selection of physical properties, only physical properties that are easily accessible were used. With this model, mass transfer calculations are possible and therefore, the output concentrations can be predicted. Simulations of an ACC based on the model were done by creating and running a python code. Validation of the model was conducted by varying and comparing operating conditions in both the simulation and the experiments. Validation was completed successfully for a representative system of components and showed good agreement over a range of rotational frequencies and temperatures.
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(This article belongs to the Special Issue Process Intensification for Chemical Engineering and Processing)
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Optimizing the Sulfates Content of Cement Using Neural Networks and Uncertainty Analysis
ChemEngineering 2023, 7(4), 58; https://doi.org/10.3390/chemengineering7040058 - 21 Jun 2023
Abstract
This study aims to approximate the optimum sulfate content of cement, applying maximization of compressive strength as a criterion for cement produced in industrial mills. The design includes tests on four types of cement containing up to three main components and belonging to
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This study aims to approximate the optimum sulfate content of cement, applying maximization of compressive strength as a criterion for cement produced in industrial mills. The design includes tests on four types of cement containing up to three main components and belonging to three strength classes. We developed relationships correlating to 7- and 28-day strength with the sulfate and clinker content of the cement (CL), as well as the clinker mineral composition (tricalcium silicate, C3S, tricalcium aluminate, C3A). We correlated strength with the ratio %SO3/CL and the molecular ratios MSO3/C3S and MSO3/C3A. The data processing stage proved that artificial neural networks (ANNs) fit the results’ distribution better than a parabolic function, providing reliable models. The optimal %SO3/CL value for 7- and 28-day strength was 2.85 and 3.00, respectively. Concerning the ratios of SO3 at the mineral phases for 28-day strength, the best values were MSO3/C3S = 0.132–0.135 and MSO3/C3A = 1.55. We implemented some of the ANNs to gain a wide interval of input variables’ values. Thus, the approximations of SO3 optimum using ANNs had a relatively broad application in daily plant quality control, at least as a guide for experimental design. Finally, we investigated the impact of SO3 uncertainty on the 28-day strength variance using the error propagation method.
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(This article belongs to the Topic Advances in Chemistry and Chemical Engineering)
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Numerical Study of Dry Reforming of Methane in Packed and Fluidized Beds: Effects of Key Operating Parameters
ChemEngineering 2023, 7(3), 57; https://doi.org/10.3390/chemengineering7030057 - 20 Jun 2023
Abstract
Replacing the conventionally used steam reforming of methane (SRM) with a process that has a smaller carbon footprint, such as dry reforming of methane (DRM), has been found to greatly improve the industry’s utilization of greenhouse gases (GHGs). In this study, we numerically
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Replacing the conventionally used steam reforming of methane (SRM) with a process that has a smaller carbon footprint, such as dry reforming of methane (DRM), has been found to greatly improve the industry’s utilization of greenhouse gases (GHGs). In this study, we numerically modeled a DRM process in lab-scale packed and fluidized beds using the Eulerian–Lagrangian approach. The simulation results agree well with the available experimental data. Based on these validated models, we investigated the effects of temperature, inlet composition, and contact spatial time on DRM in packed beds. The impacts of the side effects on the DRM process were also examined, particularly the role the methane decomposition reaction plays in coke formation at high temperatures. It was found that the coking amount reached thermodynamic equilibrium after 900 K. Additionally, the conversion rate in the fluidized bed was found to be slightly greater than that in the packed bed under the initial fluidization regime, and less coking was observed in the fluidized bed. The simulation results show that the adopted CFD approach was reliable for modeling complex flow and reaction phenomena at different scales and regimes.
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(This article belongs to the Topic Chemical and Biochemical Processes for Energy Sources)
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Mesoporous Silica-Based Catalysts for Biodiesel Production: A Review
ChemEngineering 2023, 7(3), 56; https://doi.org/10.3390/chemengineering7030056 - 16 Jun 2023
Cited by 1
Abstract
High demand for energy consumption forced the exploration of renewable energy resources, and in this context, biodiesel has received intensive attention. The process of biodiesel production itself needs to be optimized in order to make it an eco-friendly and high-performance energy resource. Within
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High demand for energy consumption forced the exploration of renewable energy resources, and in this context, biodiesel has received intensive attention. The process of biodiesel production itself needs to be optimized in order to make it an eco-friendly and high-performance energy resource. Within this scheme, development of low-cost and reusable heterogeneous catalysts has received much attention. Mesoporous silica materials with the characteristics of having a high surface area and being modifiable, tunable, and chemical/thermally stable have emerged as potential solid support of powerful catalysts in biodiesel production. This review highlights the latest updates on mesoporous silica modifications including acidic, basic, enzyme, and bifunctional catalysts derived from varied functionalization. In addition, the future outlook for progression is also discussed in detail.
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(This article belongs to the Special Issue A Themed Issue in Honor of Prof. Dr. Vicente Rives)
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Invertase Immobilization on Magnetite Nanoparticles for Efficient Fructooligosaccharide Generation: A Comprehensive Kinetic Analysis and Reactor Design Strategy
ChemEngineering 2023, 7(3), 55; https://doi.org/10.3390/chemengineering7030055 - 12 Jun 2023
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This study investigated the effectiveness of immobilizing Saccharomyces cerevisiae invertase (SInv) on magnetite nanoparticles to produce fructooligosaccharides (FOSs). Based on the existing literature and accompanied by parameter estimation, a modified kinetic model was employed to represent the kinetics of sucrose hydrolysis and transfructosylation
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This study investigated the effectiveness of immobilizing Saccharomyces cerevisiae invertase (SInv) on magnetite nanoparticles to produce fructooligosaccharides (FOSs). Based on the existing literature and accompanied by parameter estimation, a modified kinetic model was employed to represent the kinetics of sucrose hydrolysis and transfructosylation using SInv immobilized on magnetite nanoparticle surfaces. This model was utilized to simulate the performance of batch reactors for both free and immobilized enzymes. The maximum FOS concentration for the free enzyme was determined to be 123.1 mM, while the immobilized case achieved a slightly higher concentration of 125.4 mM. Furthermore, a continuous stirred-tank reactor (CSTR) model was developed for the immobilized enzyme, resulting in a maximum FOS concentration of 73.96 mM at the reactor’s outlet and a dilution rate of 14.2 h−1. To examine the impact of glucose inhibition on FOS production, a glucose oxidase reaction mechanism was integrated into the fitted immobilized theoretical model. In a batch reactor, the reduction or elimination of glucose in the reactive media led to a 2.1% increase in FOS production. Immobilizing the biocatalyst enhanced the overall performance of SInv. This enzyme immobilization approach also holds the potential for coupling glucose oxidase onto functionalized nanoparticles to minimize glucose inhibition, thereby improving FOS synthesis and facilitating optimal enzyme recovery and reuse.
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Study of Factors Affecting the Copper Ore Leaching Process
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ChemEngineering 2023, 7(3), 54; https://doi.org/10.3390/chemengineering7030054 - 09 Jun 2023
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This paper provides an overview of hydrometallurgical copper extraction studies in which liquid extraction technology has been used with four copper deposits of different compositions. The sulfuric acid consumption rate and copper extraction efficiency, which are dependent on the initial content and forms
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This paper provides an overview of hydrometallurgical copper extraction studies in which liquid extraction technology has been used with four copper deposits of different compositions. The sulfuric acid consumption rate and copper extraction efficiency, which are dependent on the initial content and forms of calcium compounds and other impurities in ore samples, were calculated, and the results are presented herein. It was established that during the leaching process, silicate compounds of alkaline earth metals, in addition to calcium and magnesium carbonate compounds, would affect the levels of sulfuric acid consumption, thereby actively lowering the acidity of the environment. Moreover, these compounds could partially sorb copper ions from sulfuric acid leaching solutions. Thus, the analysis of waste ore samples showed that residual copper is mainly contained in the form of complex silicate complexes. The presence of divalent iron compounds in the composition from one of the deposits also allowed us to perform a biochemical leaching experiment with preliminary oxidation using an Acidithiobacillus ferrooxidans bacterial culture adapted to the ore composition. The use of this biochemical method in the copper leaching process resulted in a significant reduction in sulfuric acid consumption, by 40%, and a copper recovery rate of 87.2%.
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Open AccessArticle
An Internal Model Based—Sliding Mode Control for Open-Loop Unstable Chemical Processes with Time Delay
ChemEngineering 2023, 7(3), 53; https://doi.org/10.3390/chemengineering7030053 - 02 Jun 2023
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This paper presents a dynamic sliding mode control (DSMC) for open-loop unstable chemical or biochemical processes with a time delay. The controller is based on the sliding mode and internal model control concepts. The proposed DSMC has an internal P/PD controller to provide
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This paper presents a dynamic sliding mode control (DSMC) for open-loop unstable chemical or biochemical processes with a time delay. The controller is based on the sliding mode and internal model control concepts. The proposed DSMC has an internal P/PD controller to provide systems with disturbance rejection. An identification method approximates the open-loop unstable nonlinear process to a first-order delayed unstable process (FODUP). The reduced-order model(FODUP) is used to synthesize the new controller. The performance of the controller is stable and satisfactory despite nonlinearities in the operating conditions due to set-point and process disturbance changes. In addition, the performance analysis of the control schemes was evaluated based on various indices and transient characteristics, including the integral of squared error (ISE), the total variation of control effort (TVu), the maximum overshoot (Mp), and the settling time (ts). Finally, the process output and the control action for all controllers are compared using the nonlinear process as the real plant.
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Adsorption of Lead (II) Ions onto Goethite Chitosan Beads: Isotherms, Kinetics, and Mechanism Studies
ChemEngineering 2023, 7(3), 52; https://doi.org/10.3390/chemengineering7030052 - 01 Jun 2023
Cited by 2
Abstract
Lead is a highly toxic heavy metal that creates a water pollutant. It can be released from industrial processes, agricultural chemistry, and community wastes, affecting creatures and human health even at a low concentration. As a result, it is advised that lead be
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Lead is a highly toxic heavy metal that creates a water pollutant. It can be released from industrial processes, agricultural chemistry, and community wastes, affecting creatures and human health even at a low concentration. As a result, it is advised that lead be removed before releasing wastewater into the environment. This study synthesized three chitosan bead materials from shrimp shell wastes which were chitosan powder beads (CB), chitosan powder mixed with goethite beads (CFB), and chitosan powder beads coated with goethite (CBF) for removing lead in an aqueous solution. Their surface area, pore volumes, and pore sizes were explored according to Brunauer– Emmett–Teller, and their crystalline formations were investigated using an X-ray diffractometer. Their surface structures were studied using field emission scanning electron microscopy and a focus ion beam, and their chemical compositions were determined using an energy dispersive X-ray spectrometer. Their chemical functional groups were identified via Fourier-transform infrared spectroscopy. In addition, batch experiments were conducted to investigate the effects of several factors on removing lead, and the adsorption isotherm and kinetics were also investigated for determining their adsorption pattern and mechanism. In addition, the desorption experiments were studied to confirm their possible material reusability. The CBF demonstrated the highest surface area and smallest pore size compared with the other materials. In addition, the pore sizes of the CFB and CBF were micropores, whereas those of the CB were mesopores. All materials were semicrystalline structures, and the specific goethite peaks were observed in the CFB and CBF. All materials had spherical shapes with heterogeneous surfaces. Six chemical components of O, C, Ca, N, Cl, and Na were discovered in all materials, and Fe was only found in the CFB and CBF because of the addition of goethite. Five main chemical functional groups of N–H, O–H, C–H, C–O, and –COOH were found in all materials. The optimum conditions of the CB, CFB, and CBF for removing lead were 0.5 g, 16 h, pH 5, 0.5 g, 16 h, pH 5, and 0.4 g, 14 h, pH 5, respectively. The results of the batch experiments demonstrated that the CB, CFB, and CBF were high-efficiency adsorbents for removing lead in solution by more than 95%, whereby the CBF showed the highest lead removal of 99%. The Freundlich isotherm model and pseudo-second-order kinetic model helped to well explain their adsorption pattern and mechanism. The maximum lead adsorption capacities of the CB, CFB, and CBF were 322.58, 333.33, and 344.83 mg/g, respectively. Furthermore, all chitosan materials can be reused for more than three cycles with high lead removal by more than 94%; so, they are potential materials for application in industrial applications.
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(This article belongs to the Special Issue Feature Papers in Chemical Engineering)
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