ChemEngineering

18 pages, 7328 KiB

Open AccessEditor’s ChoiceReview

Electrocatalysts for the Oxygen Reduction Reaction: From Bimetallic Platinum Alloys to Complex Solid Solutions

by Ricardo Martínez-Hincapié and Viktor Čolić

ChemEngineering 2022, 6(1), 19; https://doi.org/10.3390/chemengineering6010019 - 16 Feb 2022

Cited by 7 | Viewed by 5390

The oxygen reduction reaction has been the object of intensive research in an attempt to improve the sluggish kinetics that limit the performance of renewable energy storage and utilization systems. Platinum or platinum bimetallic alloys are common choices as the electrode material, but [...] Read more.

The oxygen reduction reaction has been the object of intensive research in an attempt to improve the sluggish kinetics that limit the performance of renewable energy storage and utilization systems. Platinum or platinum bimetallic alloys are common choices as the electrode material, but prohibitive costs hamper their use. Complex alloy materials, such as high-entropy alloys (HEAs), or more generally, multiple principal component alloys (MPCAs), have emerged as a material capable of overcoming the limitations of platinum and platinum-based materials. Theoretically, due to the large variety of active sites, this new kind of material offers the opportunity to identify experimentally the optimal binding site on the catalyst surface. This review discusses recent advances in the application of such alloys for the oxygen reduction reaction and existing experimental challenges in the benchmarking of the electrocatalytic properties of these materials. Full article

(This article belongs to the Special Issue New Insights into Electrocatalysis)

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29 pages, 36350 KiB

Open AccessArticle

A Detailed Hydrodynamic Study of the Split-Plate Airlift Reactor by Using Non-Invasive Gamma-Ray Techniques

by Laith S. Sabri, Abbas J. Sultan, Hasan Shakir Majdi, Shadha K. Jebur and Muthanna H. Al-Dahhan

ChemEngineering 2022, 6(1), 18; https://doi.org/10.3390/chemengineering6010018 - 10 Feb 2022

Cited by 7 | Viewed by 3322

Abstract

This study focused on detailed investigations of selected local hydrodynamics in split airlift reactor by using an unconventional measurements facility: computed tomography (CT) and radioactive particle tracking (RPT). The local distribution in a cross-sectional manner with its radial’s profiles for gas holdup, liquid [...] Read more.

This study focused on detailed investigations of selected local hydrodynamics in split airlift reactor by using an unconventional measurements facility: computed tomography (CT) and radioactive particle tracking (RPT). The local distribution in a cross-sectional manner with its radial’s profiles for gas holdup, liquid velocity flow field, shear stresses, and turbulent kinetic energy were studied under various gas velocity 1, 2 and 3 cm/s with various six axial level z = 12, 20, 40, 60, 90 and 112 cm. The distribution in gas–liquid phases in the whole split reactor column, the riser and downcomer sides, including their behavior at the top and bottom sections of the split plate was also described. The outcomes of this study displayed an exemplary gas–liquid phases dispersion approximately in all reactor’s zones and had large magnitude over the ring of the sparger as well as upper the split plate. Furthermore, the outcomes pointed out that the distribution of this flow may significantly impacts the performance of the split reactor, which may have essential influence on its performance particularly for microorganisms culturing applications. These outcomes are dependable as benchmark information to validate computational fluid dynamics (CFD) simulations and other models. Full article

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12 pages, 3608 KiB

Open AccessArticle

Effect of Surfactant HLB Value on Enzymatic Hydrolysis of Chitosan

by Nur Rokhati, Tutuk Djoko Kusworo, Aji Prasetyaningrum, Nur ‘Aini Hamada, Dani Puji Utomo and Teguh Riyanto

ChemEngineering 2022, 6(1), 17; https://doi.org/10.3390/chemengineering6010017 - 8 Feb 2022

Cited by 5 | Viewed by 3460

Abstract

Nonionic surfactants are reported as being able to enhance enzyme stability and increase the conversion of enzymatic reactions. Surfactant-assisted enzymatic hydrolysis conversion is affected by surfactant HLB values. This work investigated the influence of nonionic surfactants with different HLB values on chitosan enzymatic [...] Read more.

Nonionic surfactants are reported as being able to enhance enzyme stability and increase the conversion of enzymatic reactions. Surfactant-assisted enzymatic hydrolysis conversion is affected by surfactant HLB values. This work investigated the influence of nonionic surfactants with different HLB values on chitosan enzymatic hydrolysis using cellulase enzyme by measuring the reducing sugars formation, viscosity, and molecular weight of hydrolyzed chitosan. A characterization analysis of hydrolyzed products was also carried out. A higher HLB value exhibits a better enzymatic chitosan hydrolysis performance, shown by the decrease in a solution’s viscosity and the increase in reducing sugar formation. Increasing the surfactant concentration will also increase the hydrolysis rate. Nonionic surfactants can protect cellulase enzyme from the denaturation of temperature and stirring influence. The higher the HLB value, the lower the molecular weight of the hydrolyzed chitosan. The result of UV–Vis demonstrated aldehyde groups formation during hydrolysis. The SEM analysis showed that the chitosan, hydrolyzed using different HLB values of surfactants, had different surface morphologies. However, it did not change the chemical structure of the hydrolysis product seen by the FTIR analysis. The XRD patterns showed that the relative crystallinity of raw chitosan decreased when hydrolyzed with surfactants. Full article

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18 pages, 3977 KiB

Open AccessArticle

Chemical Model for Thermal Treatment of Sewage Sludge

by Corinna Netzer and Terese Løvås

ChemEngineering 2022, 6(1), 16; https://doi.org/10.3390/chemengineering6010016 - 7 Feb 2022

Cited by 8 | Viewed by 3572

Abstract

Sewage sludge is here studied as a valuable source for processing or energy conversation thanks to its high nutrition and energy content. However, various origins of the wastewater, different water cleaning technologies, and seasonal and regional dependencies lead to the high variability of [...] Read more.

Sewage sludge is here studied as a valuable source for processing or energy conversation thanks to its high nutrition and energy content. However, various origins of the wastewater, different water cleaning technologies, and seasonal and regional dependencies lead to the high variability of the sewage sludge properties. In thermal treatment units, that is, incineration, gasification and pyrolysis, sewage sludge serves as feedstock or fuel, hence a proper characterization and a mathematical description of the sewage sludge are required to estimate product streams and to formulate numerical simulations and optimization methods. The presented work introduces a surrogate concept that allows replication of sewage sludge’s ultimate composition, moisture, and ash content. The surrogate approach aims to model the decomposition of any sewage sludge sample, opposite to the established determination of kinetic rates for individual samples. Based on chemical solid surrogate species and corresponding reaction mechanisms, the thermal decomposition path is described. Sewage sludge is represented by a combination of lignocellulosic species, proteins, sugars, lipids, and representative inorganic species. The devolatilization and heterogeneous reactions are formulated such that they can be used together with a detailed gas-phase model, including tar oxidation and emission models for nitrogen and sulfur oxides, recently proposed by the authors. The developed chemical model is applied using a zero-dimensional gasification reactor in order to model weight loss within the thermogravimetric analysis, pyrolysis, gasification and combustion conditions. Weight loss, the composition of product gases, and emission release (nitrogen and sulfur oxides) are captured well by the model. The flexible surrogate approach allows us to represent various sewage sludge samples. Full article

(This article belongs to the Special Issue Thermal Treatment of Biomass and Solid Municipal Waste)

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14 pages, 1552 KiB

Open AccessArticle

Reliability of Biodegradation Measurements for Inhibitive Industrial Wastewaters

by Hanna Prokkola, Anne Heponiemi, Janne Pesonen, Toivo Kuokkanen and Ulla Lassi

ChemEngineering 2022, 6(1), 15; https://doi.org/10.3390/chemengineering6010015 - 3 Feb 2022

Cited by 3 | Viewed by 3357

Abstract

Industrial wastewaters may contain toxic or highly inhibitive compounds, which makes the measurement of biological oxygen demand (BOD) challenging. Due to the high concentration of organic compounds within them, industrial wastewater samples must be diluted to perform BOD measurements. This study focused on [...] Read more.

Industrial wastewaters may contain toxic or highly inhibitive compounds, which makes the measurement of biological oxygen demand (BOD) challenging. Due to the high concentration of organic compounds within them, industrial wastewater samples must be diluted to perform BOD measurements. This study focused on determining the reliability of wastewater BOD measurement using two different types of industrial wastewater, namely pharmaceutical wastewater containing a total organic carbon (TOC) value of 34,000 mg(C)/L and industrial paper manufacturing wastewater containing a corresponding TOC value of 30 mg(C)/L. Both manometric respirometry and the closed-bottle method were used in the study, and the results were compared. It was found that the dilution wastewaters containing inhibitive compounds affected BOD values, which increased due to the decreased inhibiting effect of wastewater pollutants. Therefore, the correct BOD for effluents should be measured from undiluted samples, while the diluted value is appropriate for determining the maximum value for biodegradable organic material in the effluent. The accuracy of the results from the blank samples was also examined, and it was found that the readings of these were different to those from the samples. Therefore, the blank value that must be subtracted may differ depending on the sample. Full article

(This article belongs to the Special Issue Feature Papers in Chemical Engineering)

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21 pages, 3185 KiB

Open AccessFeature PaperArticle

The Oxygen Paradigm—Quantitative Impact of High Concentrations of Dissolved Oxygen on Kinetics and Large-Scale Production of Arthrospira platensis

by Sabine Franke, Juliane Steingröwer, Thomas Walther and Felix Krujatz

ChemEngineering 2022, 6(1), 14; https://doi.org/10.3390/chemengineering6010014 - 2 Feb 2022

Cited by 8 | Viewed by 3588

Abstract

The cultivation of Arthrospira platensis in tubular photobioreactors (tPBRs) presents a promising approach for the commercial production of nutraceuticals and food products as it can achieve high productivity and effective process control. In closed photobioreactors, however, high amounts of photosynthetically produced oxygen can [...] Read more.

The cultivation of Arthrospira platensis in tubular photobioreactors (tPBRs) presents a promising approach for the commercial production of nutraceuticals and food products as it can achieve high productivity and effective process control. In closed photobioreactors, however, high amounts of photosynthetically produced oxygen can accumulate. So far, there has been a wide range of discussion on how dissolved oxygen concentrations (DOCs) affect bioprocess kinetics, and the subject has mainly been assessed empirically. In this study, we used photorespirometry to quantify the impact of DOCs on the growth kinetics and phycocyanin content of the widely cultivated cyanobacterium A. platensis. The photorespirometric routine revealed that the illumination intensity and cell dry weight concentration are important interconnected process parameters behind the impact that DOCs have on the bioprocess kinetics. Unfavorable process conditions such as low biomass concentrations or high illumination intensities yielded significant growth inhibition and reduced the phycocyanin content of A. platensis by up to 35%. In order to predict the biomass productivity of the large-scale cultivation of A. platensis in tPBRs, a simple process model was extended to include photoautotrophic oxygen production and accumulation in the tPBR to evaluate the performance of two configurations of a 5000 L tPBR. Full article

(This article belongs to the Special Issue Industrial Cultivation of Microalgae: Technologies, Applications and Challenges)

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18 pages, 1303 KiB

Open AccessReview

Process Intensification Strategies for Power-to-X Technologies

by Thomas Cholewa, Malte Semmel, Franz Mantei, Robert Güttel and Ouda Salem

ChemEngineering 2022, 6(1), 13; https://doi.org/10.3390/chemengineering6010013 - 2 Feb 2022

Cited by 15 | Viewed by 4957

Abstract

Sector coupling remains a crucial measure to achieve climate change mitigation targets. Hydrogen and Power-to-X (PtX) products are recognized as major levers to allow the boosting of renewable energy capacities and the consequent use of green electrons in different sectors. In this work, [...] Read more.

Sector coupling remains a crucial measure to achieve climate change mitigation targets. Hydrogen and Power-to-X (PtX) products are recognized as major levers to allow the boosting of renewable energy capacities and the consequent use of green electrons in different sectors. In this work, the challenges presented by the PtX processes are addressed and different process intensification (PI) strategies and their potential to overcome these challenges are reviewed for ammonia (NH₃), dimethyl ether (DME) and oxymethylene dimethyl ethers (OME) as three exemplary, major PtX products. PI approaches in this context offer on the one hand the maximum utilization of valuable renewable feedstock and on the other hand simpler production processes. For the three discussed processes a compelling strategy for efficient and ultimately maintenance-free chemical synthesis is presented by integrating unit operations to overcome thermodynamic limitations, and in best cases eliminate the recycle loops. The proposed intensification processes offer a significant reduction of energy consumption and provide an interesting perspective for the future development of PtX technologies. Full article

(This article belongs to the Special Issue Process Intensification for Chemical Engineering and Processing)

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10 pages, 1278 KiB

Open AccessArticle

Development of Continuous Gas Generation Method for Hydrogen Chloride Using Azeotropic Hydrochloric Acid System

by Reiji Aoyagi, Yoshika Sekine, Yuichiro Kaifuku and Kunitoshi Matsunobu

ChemEngineering 2022, 6(1), 12; https://doi.org/10.3390/chemengineering6010012 - 1 Feb 2022

Cited by 2 | Viewed by 4083

Abstract

Standard gases are often prepared using high-pressure gas cylinders. However, it is difficult to accurately prepare a known concentration of hydrogen chloride (HCl) gas using this method because HCl is highly corrosive and adsorptive. In this study, a simple method for the continuous [...] Read more.

Standard gases are often prepared using high-pressure gas cylinders. However, it is difficult to accurately prepare a known concentration of hydrogen chloride (HCl) gas using this method because HCl is highly corrosive and adsorptive. In this study, a simple method for the continuous generation of HCl gas was developed using a diffusion tube containing hydrochloric acid and a nitrogen carrier gas. The concentration of HCl produced from this system was almost unstable, but constant gas generation was realized for several hours when azeotropic hydrochloric acid (20.6% HCl in water) and a temperature near the azeotropic point (108.5 °C) were used, resulting in the generation of 103.6 ppm (mean, n = 5) of HCl gas with a relative standard deviation (RSD) of 2.34%. In this case, the percentage of HCl present in the entire gas mixture of HCl and water vapor was 22.5%, which is almost equivalent to the HCl content in the azeotropic hydrochloric acid (20.6%). The HCl concentration could also be controlled by changing the flow rate of the carrier gas. This work demonstrates a simple technique based on the diffusion theory that allows for the constant, controllable generation of a known concentration of HCl gas using an azeotropic hydrochloric acid system. Full article

(This article belongs to the Special Issue Chemical Engineering and Multidisciplinary)

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20 pages, 6037 KiB

Open AccessArticle

Numerical Simulation of Heat and Mass Transfer in an Open-Cell Foam Catalyst on Example of the Acetylene Hydrogenation Reaction

by Sergei A. Solovev, Olga V. Soloveva, Irina G. Akhmetova, Yuri V. Vankov and Daniel L. Paluku

ChemEngineering 2022, 6(1), 11; https://doi.org/10.3390/chemengineering6010011 - 1 Feb 2022

Cited by 19 | Viewed by 3711

Abstract

In the present work, based on numerical simulation, a comparative analysis of the flow of a chemically reacting gas flow through a catalyst is performed using the example of selective hydrogenation of acetylene in a wide range of flow temperatures variation. Catalyst models [...] Read more.

In the present work, based on numerical simulation, a comparative analysis of the flow of a chemically reacting gas flow through a catalyst is performed using the example of selective hydrogenation of acetylene in a wide range of flow temperatures variation. Catalyst models are based on open-cell foam material. A comparison is also made with calculations and experimental data for a granular catalyst. The porosity and cell diameter were chosen as variable parameters for the porous catalyst. The results of numerical studies were obtained in the form of component concentration fields of the gas mixture, vector fields of gas movement, values of conversion, and selectivity of the reaction under study. The parameters of the porous material of the catalyst are determined for the maximum efficiency of the process under study. Full article

(This article belongs to the Special Issue Feature Papers in Chemical Engineering)

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8 pages, 2307 KiB

Open AccessArticle

Poly(Lactic-co-glycolic) Acid and Phospholipids Hybrid Nanoparticles for Regeneration of Biological Tissue

by Antonio Minó, Giuseppe Cinelli, Gianluca Paventi, Gianluca Testa, Fabiana Passaro, Francesco Lopez and Luigi Ambrosone

ChemEngineering 2022, 6(1), 10; https://doi.org/10.3390/chemengineering6010010 - 27 Jan 2022

Cited by 2 | Viewed by 2436

Abstract

In tissue regeneration, biomaterials facilitate biological processes. However, a treatment with biomaterials will be successful only if supported by simple and inexpensive technologies which stimulate the regenerative processes. The present study focused on the possibility of creating formulations from which then to obtain [...] Read more.

In tissue regeneration, biomaterials facilitate biological processes. However, a treatment with biomaterials will be successful only if supported by simple and inexpensive technologies which stimulate the regenerative processes. The present study focused on the possibility of creating formulations from which then to obtain suitable materials for the regeneration of heart tissue. The experimental procedure for precipitation of polymer- nanoparticles was modified ad hoc to obtain hybrid poly lactic-co-glycolic acid (PLGA)-phospholipid nanoparticles. The properties of the formulations produced by direct PLGA-phospholipid co-precipitation depend on the mass ratio

R =

polymer mass/phospholipid mass. The value of this parameter allows us to modulate the properties of the formulations. Formulations with

R

= 1.5, 2.3, 4, and 9 were prepared, and for each of them the particle-size distribution obtained by dynamic light scattering was studied. All samples showed that the hydrodynamic diameter decreases with increasing

R

value. This behavior is interpreted as polymer coil shrinkage due to contacts with the non-solvent. The spreadability and ease of obtaining thin sheets were evaluated for each formulation. The formulation with

R = 4

resulted in a homogeneous and easily workable material in thin sheets. Full article

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3 pages, 176 KiB

Open AccessEditorial

Acknowledgment to Reviewers of ChemEngineering in 2021

by ChemEngineering Editorial Office

ChemEngineering 2022, 6(1), 9; https://doi.org/10.3390/chemengineering6010009 - 24 Jan 2022

Viewed by 1866

Abstract

Rigorous peer-reviews are the basis of high-quality academic publishing [...] Full article

22 pages, 1781 KiB

Open AccessEditor’s ChoiceReview

Key Points of Advanced Oxidation Processes (AOPs) for Wastewater, Organic Pollutants and Pharmaceutical Waste Treatment: A Mini Review

by Pavlos K. Pandis, Charalampia Kalogirou, Eirini Kanellou, Christos Vaitsis, Maria G. Savvidou, Georgia Sourkouni, Antonis A. Zorpas and Christos Argirusis

ChemEngineering 2022, 6(1), 8; https://doi.org/10.3390/chemengineering6010008 - 18 Jan 2022

Cited by 167 | Viewed by 19625

Abstract

Advanced oxidation procedures (AOPs) refer to a variety of technical procedures that produce OH radicals to sufficiently oxidize wastewater, organic pollutant streams, and toxic effluents from industrial, hospital, pharmaceutical and municipal wastes. Through the implementation of such procedures, the (post) treatment of such [...] Read more.

Advanced oxidation procedures (AOPs) refer to a variety of technical procedures that produce OH radicals to sufficiently oxidize wastewater, organic pollutant streams, and toxic effluents from industrial, hospital, pharmaceutical and municipal wastes. Through the implementation of such procedures, the (post) treatment of such waste effluents leads to products that are more susceptible to bioremediation, are less toxic and possess less pollutant load. The basic mechanism produces free OH radicals and other reactive species such as superoxide anions, hydrogen peroxide, etc. A basic classification of AOPs is presented in this short review, analyzing the processes of UV/H₂O₂, Fenton and photo-Fenton, ozone-based (O₃) processes, photocatalysis and sonolysis from chemical and equipment points of view to clarify the nature of the reactive species in each AOP and their advantages. Finally, combined AOP implementations are favored through the literature as an efficient solution in addressing the issue of global environmental waste management. Full article

(This article belongs to the Special Issue Feature Papers in Chemical Engineering)

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14 pages, 2693 KiB

Open AccessFeature PaperArticle

Prediction of B20 Storage Tank Precipitate Removal Based on Biodiesel Monoglyceride Content

by Misri Gozan, Imam Paryanto, Muhammad Arif Darmawan, Muhammad Sahlan, Heri Hermansyah, Eriawan Rismana, Alfan Danny Arbianto, Tirto Prakoso, Mohamed Kheireddine Aroua and Patrick Cognet

ChemEngineering 2022, 6(1), 7; https://doi.org/10.3390/chemengineering6010007 - 13 Jan 2022

Cited by 1 | Viewed by 3024

Abstract

Precipitate in B20 fuel stored in storage tanks can accumulate at the bottom level of the tank and affect the fuel filter, clogging in the fuel distribution and engine system. This study examines the precipitate formation prediction in B20 fuel based on the [...] Read more.

Precipitate in B20 fuel stored in storage tanks can accumulate at the bottom level of the tank and affect the fuel filter, clogging in the fuel distribution and engine system. This study examines the precipitate formation prediction in B20 fuel based on the monoglyceride content in biodiesel. This research used a modified CSFT method of ASTM D7501 for the precipitation test. Monopalmitin was added to biodiesel with a variation of monoglyceride content. Each biodiesel sample was then blended with petroleum diesel fuel to produce two groups of samples. Each sample was separately soaked in the cooling chamber at constant and room temperature for 21 days. The bottom layer of each B20 fuel sample stored in the measuring cylinder was then pipetted and filtered, washed with petro-ether, vacuum-dried, and weighed for a constant amount of precipitate retained on the filter. The simulation results show that the ratios between the amount of collected precipitate at the bottom layer of the 2-liter measuring cylinder and the total amount of collected precipitate for the 2-liter measuring cylinder increased with the monoglyceride content biodiesel. This ratio was used to predict the amount of accumulated sludge for a given volume of B20 fuel loaded into the storage tank. This study shows the effect of monoglyceride content on the precipitation behaviour in the storage tank concerning general tank storage dimension parameters and B20 loading frequency. This approach can be applied to estimate the sludge removal frequency for biodiesel storage. Full article

(This article belongs to the Special Issue Feature Papers in Chemical Engineering)

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21 pages, 349 KiB

Open AccessReview

Ionic Liquids as Components of Systems for Metal Extraction

by Pavel A. Yudaev and Evgeniy M. Chistyakov

ChemEngineering 2022, 6(1), 6; https://doi.org/10.3390/chemengineering6010006 - 6 Jan 2022

Cited by 27 | Viewed by 7414

Abstract

This review addresses research and development on the use of ionic liquids as extractants and diluents in the solvent extraction of metals. Primary attention is given to the efficiency and selectivity of metal extraction from industrial wastewater with ionic liquids composed of various [...] Read more.

This review addresses research and development on the use of ionic liquids as extractants and diluents in the solvent extraction of metals. Primary attention is given to the efficiency and selectivity of metal extraction from industrial wastewater with ionic liquids composed of various cations and anions. The review covers literature sources published in the period of 2010–2021. The bibliography includes 98 references dedicated to research on the extraction and separation of lanthanides (17 sources), actinides (5 sources), heavy metals (35 sources), noble metals, including the platinum group (16 sources), and some other metals. Full article

(This article belongs to the Special Issue Ionic Liquids as New Alternative Engineering Solvents)

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16 pages, 10066 KiB

Open AccessReview

Recent Developments in Supercapacitor Electrodes: A Mini Review

by Sumedha Harike Nagarajarao, Apurva Nandagudi, Ramarao Viswanatha, Basavanakote Mahadevappa Basavaraja, Mysore Sridhar Santosh, Beekanahalli Mokshanatha Praveen and Anup Pandith

ChemEngineering 2022, 6(1), 5; https://doi.org/10.3390/chemengineering6010005 - 5 Jan 2022

Cited by 39 | Viewed by 9041

Abstract

The use of nonrenewable fossil fuels for energy has increased in recent decades, posing a serious threat to human life. As a result, it is critical to build environmentally friendly and low-cost reliable and renewable energy storage solutions. The supercapacitor is a future [...] Read more.

The use of nonrenewable fossil fuels for energy has increased in recent decades, posing a serious threat to human life. As a result, it is critical to build environmentally friendly and low-cost reliable and renewable energy storage solutions. The supercapacitor is a future energy device because of its higher power density and outstanding cyclic stability with a quick charge and discharge process. Supercapacitors, on the other hand, have a lower energy density than regular batteries. It is well known that the electrochemical characteristic of supercapacitors is strongly dependent on electrode materials. The current review highlights advance in the TMOs for supercapacitor electrodes. In addition, the newly discovered hybrid/pseudo-supercapacitors have been discussed. Metal oxides that are employed as electrode materials are the focus of this study. The discovery of nanostructured electrode materials continues to be a major focus of supercapacitor research. To create high-performance electrode materials from a morphological standpoint, various efforts have been attempted. Lastly, we analyze the supercapacitor’s evolving trend and our perspective for the future generations of supercapacitors. Full article

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9 pages, 2171 KiB

Open AccessArticle

Experimental Study on Absorption Behavior and Efficiency of Brine in Hazardous Gas Absorption Treatment

by Ga-young Jung, Seul-gi Lee, Jun-seo Lee and Byung-chol Ma

ChemEngineering 2022, 6(1), 4; https://doi.org/10.3390/chemengineering6010004 - 4 Jan 2022

Cited by 1 | Viewed by 2609

Abstract

There have been studies recently on bubble-column scrubbers with low cost and high efficiency for the absorption and treatment of hazardous gases in the event of a chemical spill. Bubble columns are vulnerable to freezing at temperatures below zero because the absorbents generally [...] Read more.

There have been studies recently on bubble-column scrubbers with low cost and high efficiency for the absorption and treatment of hazardous gases in the event of a chemical spill. Bubble columns are vulnerable to freezing at temperatures below zero because the absorbents generally do not circulate. To address this issue, this study focused on the applicability, absorbed amount, and performance of brine as an absorbent. Under three different temperatures, i.e., −5 °C, −8 °C and −10 °C we examined brine (NaCl, CaCl₂, and MgCl₂) by varying the concentration required at each temperature. Following the experiments, CaCl₂ brine was determined as the optimal brine for its absorption performance and affordability. Based on the experimental results, the absorption performance for ammonia, ethylene oxide, and methylamine, which are hazardous and water-soluble gases among accident preparedness substances (APS), was tested by using ASEPN PLUS. Our results suggested although the efficiency dropped by about 5% to 25% when brine was used as an absorbent, it can be used at the low temperatures because the gas solubility increased with decreasing temperature. Therefore, if brine, as an alternative, is used at temperatures about 15 °C, it can operate efficiently and stably without deterioration in the absorption performance. Given our experimental results and design data on the absorbed amount and absorbent replacement period for major hazardous gases are utilized to prevent bubble columns from freezing, it can be commercially used for small and medium-sized enterprises because it can help reduce installation and operation costs. Full article

(This article belongs to the Special Issue Feature Papers in Chemical Engineering)

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16 pages, 2890 KiB

Open AccessArticle

Development of Integrated Electrocoagulation-Sedimentation (IECS) in Continuous Mode for Turbidity and Color Removal

by Saret Bun, Penghour Hong, Nattawin Chawaloesphosiya, Sreynich Pang, Sreyla Vet, Phaly Ham, Rathborey Chan and Pisut Painmanakul

ChemEngineering 2022, 6(1), 3; https://doi.org/10.3390/chemengineering6010003 - 4 Jan 2022

Cited by 3 | Viewed by 2926

Abstract

The present work focused on the development and evaluation of a compact electrocoagulation (EC) reactor, combined between EC and clarifier processes in continuous modes for decolorization and turbidity removal, named the integrated electrocoagulation-sedimentation reactor (IECS). The experiments were firstly conducted in the four-liter [...] Read more.

The present work focused on the development and evaluation of a compact electrocoagulation (EC) reactor, combined between EC and clarifier processes in continuous modes for decolorization and turbidity removal, named the integrated electrocoagulation-sedimentation reactor (IECS). The experiments were firstly conducted in the four-liter batch column in order to optimize the EC configuration and operation condition. The removal kinetics were also investigated and predicted for kinetic correlations. After various optimization steps, the IECS reactor was conducted, consisting of EC and clarifier compartments. Liquid flow pattern in EC compartment was examined through resident time distribution technique for defining the number of EC units and divided baffles. In summary, four units of EC were placed in the EC compartment of the IECS reactor with 90% in the width of three baffles. Each EC unit had two pairs of aluminum electrode plats in monopolar arrangement with a 1.5 cm gap and required a current density of 13.5 mA/cm². For the clarifier compartment, it was mainly designed based on the batch settling test for separating the precipitated particles. The treatment performance of the IECS reactor was tested at different liquid flows in order to reduce the pollutant to a certain level. For the individual condition, liquid flow rates of 3 and 1 L/min were defined for turbidity and color, respectively. If both pollutants are presented simultaneously, a liquid flow rate of 1–2 L/min can be used for decreasing turbidity from 250 to <20 NTU and color from 6000 to <300 ADMI. Full article

(This article belongs to the Special Issue Chemical Engineering and Multidisciplinary)

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21 pages, 2911 KiB

Open AccessArticle

Evaluation of the Heat Produced by the Hydrothermal Liquefaction of Wet Food Processing Residues and Model Compounds

by Morgane Briand, Geert Haarlemmer, Anne Roubaud and Pascal Fongarland

ChemEngineering 2022, 6(1), 2; https://doi.org/10.3390/chemengineering6010002 - 4 Jan 2022

Cited by 5 | Viewed by 3483

Abstract

Hydrothermal liquefaction has proven itself as a promising pathway to the valorisation of low-value wet food residues. The chemistry is complex and many questions remain about the underlying mechanism of the transformation. Little is known about the heat of reaction, or even the [...] Read more.

Hydrothermal liquefaction has proven itself as a promising pathway to the valorisation of low-value wet food residues. The chemistry is complex and many questions remain about the underlying mechanism of the transformation. Little is known about the heat of reaction, or even the thermal effects, of the hydrothermal liquefaction of real biomass and its constituents. This paper explores different methods to evaluate the heat released during the liquefaction of blackcurrant pomace and brewers’ spent grains. Some model compounds have also been evaluated, such as lignin, cellulose and glutamic acid. Exothermic behaviour was observed for blackcurrant pomace and brewers’ spent grains. Results obtained in a continuous reactor are similar to those obtained in a batch reactor. The heat release has been estimated between 1 MJ/kg and 3 MJ/kg for blackcurrant pomace and brewers’ spent grains, respectively. Liquefaction of cellulose and glucose also exhibit exothermic behaviour, while the transformation of lignin and glutamic acid present a slightly endothermic behaviour. Full article

(This article belongs to the Special Issue Feature Papers in Chemical Engineering)

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12 pages, 6504 KiB

Open AccessArticle

Study on Behavior of the Heat Exchanger with Conically-Corrugated Tubes and HDD Baffles

by Zhiwei Wu and Caifu Qian

ChemEngineering 2022, 6(1), 1; https://doi.org/10.3390/chemengineering6010001 - 2 Jan 2022

Cited by 4 | Viewed by 2906

Abstract

Baffles with holes in different diameters (or HDD baffles) and conically-corrugated tubes are respectively longitudinal flow baffle and high-efficiency heat exchange tubes proposed by the author. In this paper, vibrations of tube bundles with HDD baffles and fluid flow as well as heat [...] Read more.

Baffles with holes in different diameters (or HDD baffles) and conically-corrugated tubes are respectively longitudinal flow baffle and high-efficiency heat exchange tubes proposed by the author. In this paper, vibrations of tube bundles with HDD baffles and fluid flow as well as heat transfer inside conically-corrugated tubes were numerically simulated, and the heat exchanger with conically-corrugated tubes and HDD baffles was tested for the heat transfer efficiency. It is found that compared with the traditional segmental baffles, tube bundle vibrations in heat exchangers, if using the HDD baffles, can be significantly reduced. Regarding heat transfer efficiency, conically-corrugated tubes are much better than smooth tubes and even better than other high-efficiency heat transfer tubes. Compared with the traditional heat exchangers, heat exchangers constructed with conically-corrugated tubes and the HDD baffles can provide better heat transfer efficiency and less tube bundle vibration. Full article

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ChemEngineering, Volume 6, Issue 1 (February 2022) – 19 articles

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