ChemEngineering

10 pages, 7709 KiB

Open AccessCommunication

Synthesis of ZnS/Al₂O₃/TaSe₂ Core/Shell Nanowires Using Thin Ta Metal Film Precursor

by Boris Polyakov, Kevon Kadiwala, Edgars Butanovs, Luize Dipane, Annamarija Trausa, Dmitry Bocharov and Sergei Vlassov

ChemEngineering 2024, 8(1), 25; https://doi.org/10.3390/chemengineering8010025 - 19 Feb 2024

Viewed by 1252

Abstract

This study introduces a novel approach for fabricating ZnS/Al₂O₃/TaSe₂ heterostructured core/shell nanowires (NWs) through the selenization of a metallic Ta thin film precursor. The synthesis process involves a meticulously designed four-step protocol: (1) generating ZnS NWs on an [...] Read more.

This study introduces a novel approach for fabricating ZnS/Al₂O₃/TaSe₂ heterostructured core/shell nanowires (NWs) through the selenization of a metallic Ta thin film precursor. The synthesis process involves a meticulously designed four-step protocol: (1) generating ZnS NWs on an oxidized silicon substrate, (2) encapsulating these NWs with a precisely controlled thin Al₂O₃ layer via atomic layer deposition (ALD), (3) applying a Ta precursor layer by magnetron sputtering, and (4) annealing in a Se-rich environment in a vacuum-sealed quartz ampoule to transform the Ta layer into TaSe₂, resulting in the final core/shell structure. The characterization of the newly produced NWs using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) was validated using the integrity and composition of the heterostructures. Our method not only establishes a new pathway for the synthesis of TaSe₂-based core/shell NWs but also extends the potential for creating a variety of core/shell NW systems with chalcogenide shells by adapting the thin film metal precursor approach. This versatility opens the way for future advancements in nanoscale material applications, particularly in electronics and optoelectronics where core/shell geometries are increasingly important. Full article

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29 pages, 5047 KiB

Open AccessArticle

Fall and Rise: Disentangling Cycle Life Trends in Atmospheric Plasma-Synthesized FeOOH/PANI Composite for Conversion Anodes in Lithium-Ion Batteries

by Evgenii V. Beletskii, Alexey I. Volkov, Ksenia A. Kharisova, Oleg V. Glumov, Maksim A. Kamarou, Daniil A. Lukyanov and Oleg V. Levin

ChemEngineering 2024, 8(1), 24; https://doi.org/10.3390/chemengineering8010024 - 10 Feb 2024

Viewed by 1251

Abstract

Various iron oxides have been proven to be promising anode materials for metal-ion batteries due to their natural abundance, high theoretical capacity, ease of preparation, and environmental friendliness. However, the synthesis of iron oxide-based composites requires complex approaches, especially when it comes to [...] Read more.

Various iron oxides have been proven to be promising anode materials for metal-ion batteries due to their natural abundance, high theoretical capacity, ease of preparation, and environmental friendliness. However, the synthesis of iron oxide-based composites requires complex approaches, especially when it comes to composites with intrinsically conductive polymers. In this work, we propose a one-step microplasma synthesis of polyaniline-coated urchin-like FeOOH nanoparticles (FeOOH/PANI) for applications as anodes in lithium-ion batteries. The material shows excellent electrochemical properties, providing an initial capacity of ca. 1600 mA∙h∙g⁻¹ at 0.05 A∙g⁻¹ and 900 mA∙g⁻¹ at 1.2 A∙g⁻¹. Further cycling led to a capacity decrease to 150 mA∙h∙g⁻¹ by the 60th cycle, followed by a recovery that maintained the capacity at 767 mA∙h∙g⁻¹ after 2000 cycles at 1.2 A∙g⁻¹ and restored the full initial capacity of 1600 mA∙h∙g⁻¹ at a low current density of 0.05 A∙g⁻¹. Electrochemical milling—the phenomenon we confirmed via a combination of physico-chemical and electrochemical techniques—caused the material to exhibit interesting behavior. The anodes also exhibited high performance in a full cell with NMC532, which provided an energy density of 224 Wh∙kg⁻¹, comparable to the reference cell with a graphite anode (264 Wh∙kg⁻¹). Full article

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16 pages, 1279 KiB

Open AccessReview

A Review on Lanthanum-Based Materials for Phosphate Removal

by Sundarakannan Rajendran, A. V. S. L. Sai Bharadwaj, Praveen Barmavatu, Geetha Palani, Herri Trilaksanna, Karthik Kannan and Nagaraj Meenakshisundaram

ChemEngineering 2024, 8(1), 23; https://doi.org/10.3390/chemengineering8010023 - 09 Feb 2024

Viewed by 1309

Abstract

In the past decade, eutrophication and phosphate recovery from surface water have become major issues. Adsorption is an effective method for phosphate removal because of its high efficiency. Even though lanthanum-based compounds are effective at removing phosphate from water, outside factors influence them. [...] Read more.

In the past decade, eutrophication and phosphate recovery from surface water have become major issues. Adsorption is an effective method for phosphate removal because of its high efficiency. Even though lanthanum-based compounds are effective at removing phosphate from water, outside factors influence them. Hence, it is vital to develop and employ cost-effective innovations to fulfill ever-tougher requirements and address the issue of water contamination. Adsorption technology is highly effective in phosphate removal at concentrations from wastewater. This work briefly describes the preparation of lanthanum nano-adsorbents for the removal of phosphate efficiently in water, and phosphate adsorption on La-based adsorbents in various La forms. The work presented in this study offers an outline for future phosphate adsorption studies in La-based adsorbents, resulting in La-based materials with substantial adsorption capacity and strong regeneration capability. Full article

(This article belongs to the Collection Green and Environmentally Sustainable Chemical Processes)

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12 pages, 4482 KiB

Open AccessBrief Report

Chemical Species Formed on FeB-Fe₂B Layers during Wet Sliding Wear Test

by Ricardo Andrés García-León and Nelson Afanador-García

ChemEngineering 2024, 8(1), 22; https://doi.org/10.3390/chemengineering8010022 - 09 Feb 2024

Viewed by 1076

Abstract

In the present work, X-ray photoelectron spectroscopy (XPS) survey spectra of borided AISI 316L for two different times (1 and 6 h) of exposure to simulated body fluid (SBF) were obtained after wet sliding wear. A borided layer of ~39 microns was obtained [...] Read more.

In the present work, X-ray photoelectron spectroscopy (XPS) survey spectra of borided AISI 316L for two different times (1 and 6 h) of exposure to simulated body fluid (SBF) were obtained after wet sliding wear. A borided layer of ~39 microns was obtained on the surface of the AISI 316L stainless steel using the thermochemical treatment of boriding. As part of the mechanical and chemical characterization of sliding wear, Berkovich nanoindentation and X-ray spectroscopy tests were used to determine the main properties of the borided layer. The results of the specific wear rate values were higher at 5 mm/s sliding speed than those recorded at 30 mm/s due to the influence of the exposure time of the sample and the complex combinations of chemical reactions with boron (e.g., B₂S₃, Cr₂O₃, and Fe₂O₃) on the surface during the sliding during 6 h of exposure in Hank’s solution due to the formation of the passive film. The knowledge of chemical species formed during wet sliding wear tests on borided AISI 316L is essential for understanding wear mechanisms and materials’ performance and optimizing material properties and materials’ and components’ reliability in the biomedical industry for screws and fastening plates. Full article

(This article belongs to the Topic Advances in Chemistry and Chemical Engineering)

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22 pages, 3462 KiB

Open AccessArticle

Insight into the Structural and Dynamical Processes of Peptides by Means of Vibrational and Ultrasonic Relaxation Spectroscopies, Molecular Docking, and Density Functional Theory Calculations

by Afrodite Tryfon, Panagiota Siafarika, Constantine Kouderis and Angelos G. Kalampounias

ChemEngineering 2024, 8(1), 21; https://doi.org/10.3390/chemengineering8010021 - 06 Feb 2024

Viewed by 1126

Abstract

We report a detailed investigation of the vibrational modes, structure, and dynamics of glutathione (GSH) solutions using ultrasonic relaxation spectroscopy, FT-IR vibrational spectroscopy, and electronic absorption measurements. The experimental data were analyzed using density functional theory (DFT) and molecular docking calculations. Three distinct [...] Read more.

We report a detailed investigation of the vibrational modes, structure, and dynamics of glutathione (GSH) solutions using ultrasonic relaxation spectroscopy, FT-IR vibrational spectroscopy, and electronic absorption measurements. The experimental data were analyzed using density functional theory (DFT) and molecular docking calculations. Three distinct Debye-type relaxation processes can be observed in the acoustic spectra, which are assigned to conformational changes between GSH conformers, the self-association of GSH, and protonation processes. The standard volume changes for each process were estimated both experimentally and theoretically, revealing a close resemblance among them. The higher the effect of the relaxation process in the structure, the greater the induced volume changes. From the temperature dependence of specific acoustic parameters, the thermodynamic characteristics of each process were determined. The experimental FT-IR spectra were compared with the corresponding theoretically predicted vibrational spectra, revealing that the GSH dimers and extended conformers dominate the structure of GSH solutions in the high-concentration region. The absorption spectra in the ultraviolet region confirmed the gradual aggregation mechanism that takes place in the aqueous GSH solutions. The results of the present study were discussed and analyzed in the framework of the current phenomenological status of the field. Full article

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

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12 pages, 3032 KiB

Open AccessArticle

Novel Bi-Functional MoS₂/α-Fe₂O₃ Nanocomposites for High Photocatalytic Performance

by Islam Ibrahim, Pinelopi P. Falara, Elias Sakellis, Maria Antoniadou, Chrysoula Athanasekou and Michalis K. Arfanis

ChemEngineering 2024, 8(1), 20; https://doi.org/10.3390/chemengineering8010020 - 06 Feb 2024

Viewed by 1167

Abstract

In this study, 3-dimensional molybdenum disulfide (MoS₂) structures, integrated with hematite (α-Fe₂O₃) nanoparticles, were fabricated under a convenient two-step hydrothermal route. The fabricated photocatalytic nanocomposites consist of well-arranged MoS₂ flakes, resembling spherical flower-like morphology, and the [...] Read more.

In this study, 3-dimensional molybdenum disulfide (MoS₂) structures, integrated with hematite (α-Fe₂O₃) nanoparticles, were fabricated under a convenient two-step hydrothermal route. The fabricated photocatalytic nanocomposites consist of well-arranged MoS₂ flakes, resembling spherical flower-like morphology, and the nanoparticulate α-Fe₂O₃ structures decorate the 3D network. By raising the α-Fe₂O₃ weight ratio, the composites’ specific surface area and morphology were not affected, regardless of the partial cover of the cavities for higher hematite content. Moreover, the crystallinity examination with XRD, Raman, and FTIR techniques revealed that the precursor reagents were fully transformed to well-crystalized MoS₂ and Fe₂O₃ composites of high purity, as no organic or inorganic residues could be detected. The photocatalytic oxidation and reduction performance of these composites was evaluated against the tetracycline pharmaceutical and the industrial pollutant hexavalent chromium, respectively. The improvement in the removal efficiencies demonstrates that the superior photoactivity originates from the high crystallinity and homogeneity of the composite, in combination with the enhanced charge carriers’ separation in the semiconductors’ interface. Full article

(This article belongs to the Special Issue The Synthesis, Characterization, and Application of Novel Photocatalytic Materials)

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13 pages, 9431 KiB

Open AccessCommunication

Zinc Oxide Tetrapods Doped with Silver Nanoparticles as a Promising Substrate for the Detection of Biomolecules via Surface-Enhanced Raman Spectroscopy

by Edgars Vanags, Ivita Bite, Liga Ignatane, Reinis Ignatans, Annamarija Trausa, Ciro Federiko Tipaldi, Karlis Vilks and Krisjanis Smits

ChemEngineering 2024, 8(1), 19; https://doi.org/10.3390/chemengineering8010019 - 04 Feb 2024

Viewed by 1204

Abstract

In this study, we report the fabrication and characterization of silver nanoparticle-doped zinc oxide tetrapod substrates used for surface-enhanced Raman scattering to detect rhodamine B. Prior to this, silver nanoparticle-doped zinc oxide tetrapods were synthesized using the solar physical vapor deposition method. Subsequently, [...] Read more.

In this study, we report the fabrication and characterization of silver nanoparticle-doped zinc oxide tetrapod substrates used for surface-enhanced Raman scattering to detect rhodamine B. Prior to this, silver nanoparticle-doped zinc oxide tetrapods were synthesized using the solar physical vapor deposition method. Subsequently, silver-doped zinc oxide tetrapods were applied onto silicon wafers via the droplet evaporation process. The surface-enhanced Raman scattering activity of the silver nanoparticle-doped zinc oxide tetrapod substrate was evaluated by detecting rhodamine B using Raman spectroscopy. Our results demonstrate that the silver nanoparticle-doped zinc oxide tetrapod substrate exhibits surface-enhanced Raman scattering activity and can detect rhodamine B at concentrations as low as 3 μg/mL. This study suggests that silver nanoparticle-doped zinc oxide tetrapod substrates have potential as surface-enhanced Raman scattering platforms as well as potential for the detection of biomolecules. Full article

(This article belongs to the Special Issue Advanced Chemical Engineering in Nanoparticles)

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Graphical abstract

15 pages, 8961 KiB

Open AccessArticle

Characterization and Thermal Evaluation of a Novel Bio-Based Natural Insulation Material from Posidonia oceanica Waste: A Sustainable Solution for Building Insulation in Algeria

by Dhouha Ben Hadj Tahar, Zakaria Triki, Mohamed Guendouz, Hichem Tahraoui, Meriem Zamouche, Mohammed Kebir, Jie Zhang and Abdeltif Amrane

ChemEngineering 2024, 8(1), 18; https://doi.org/10.3390/chemengineering8010018 - 02 Feb 2024

Viewed by 1485

Abstract

Natural bio-based insulation materials have been the most interesting products for good performance and low carbon emissions, becoming widely recognized for their sustainability in the context of climate change and the environmental impact of the building industry. The main objective of this study [...] Read more.

Natural bio-based insulation materials have been the most interesting products for good performance and low carbon emissions, becoming widely recognized for their sustainability in the context of climate change and the environmental impact of the building industry. The main objective of this study is to characterize a new bio-sourced insulation material composed of fibers and an adhesive based on cornstarch. This innovative material is developed from waste of the marine plant called Posidonia oceanica (PO), abundantly found along the Algerian coastline. The research aims to valorize this PO waste by using it as raw material to create this novel material. Four samples with different volumetric adhesive fractions (15%, 20%, 25%, and 30%) were prepared and tested. The collected fractions underwent a series of characterizations to evaluate their properties. The key characteristics studied include density, thermal conductivity, and specific heat. The results obtained for the thermal conductivity of the different composites range between 0.052 and 0.067 W.m⁻¹.K⁻¹. In addition, the findings for thermal diffusivity and specific heat are similar to those reported in the scientific literature. However, the capillary absorption of the material is slightly lower, which indicates that the developed bio-sourced material exhibits interesting thermal performance, justifying its suitability for use in building insulation in Algeria. Full article

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31 pages, 1445 KiB

Open AccessReview

An Overview of Hydrogen Energy Generation

by Gaydaa AlZohbi

ChemEngineering 2024, 8(1), 17; https://doi.org/10.3390/chemengineering8010017 - 01 Feb 2024

Viewed by 1968

Abstract

The global issue of climate change caused by humans and its inextricable linkage to our present and future energy demand presents the biggest challenge facing our globe. Hydrogen has been introduced as a new renewable energy resource. It is envisaged to be a [...] Read more.

The global issue of climate change caused by humans and its inextricable linkage to our present and future energy demand presents the biggest challenge facing our globe. Hydrogen has been introduced as a new renewable energy resource. It is envisaged to be a crucial vector in the vast low-carbon transition to mitigate climate change, minimize oil reliance, reinforce energy security, solve the intermittency of renewable energy resources, and ameliorate energy performance in the transportation sector by using it in energy storage, energy generation, and transport sectors. Many technologies have been developed to generate hydrogen. The current paper presents a review of the current and developing technologies to produce hydrogen from fossil fuels and alternative resources like water and biomass. The results showed that reformation and gasification are the most mature and used technologies. However, the weaknesses of these technologies include high energy consumption and high carbon emissions. Thermochemical water splitting, biohydrogen, and photo-electrolysis are long-term and clean technologies, but they require more technical development and cost reduction to implement reformation technologies efficiently and on a large scale. A combination of water electrolysis with renewable energy resources is an ecofriendly method. Since hydrogen is viewed as a considerable game-changer for future fuels, this paper also highlights the challenges facing hydrogen generation. Moreover, an economic analysis of the technologies used to generate hydrogen is carried out in this study. Full article

(This article belongs to the Special Issue Advances in Hydrotreating Catalyst Synthesis for Fuel and Chemical Production Processes)

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15 pages, 1749 KiB

Open AccessArticle

Enhancing Recovery Yield of Vegetable Oil Methyl Ester for Bioresin Production: A Comparison Study Using Acid Neutralization

by Md. Sanaul Huda, Michael Odegaard, Niloy Chandra Sarker, Dean C. Webster and Ewumbua Monono

ChemEngineering 2024, 8(1), 16; https://doi.org/10.3390/chemengineering8010016 - 01 Feb 2024

Viewed by 1208

Abstract

Vegetable oil methyl ester has promising properties for bio-based resin production due to its higher degree of unsaturation. The initial low methyl ester yield from corn oil compared to soybean and canola oils requires further investigation of the influence of neutralization at the [...] Read more.

Vegetable oil methyl ester has promising properties for bio-based resin production due to its higher degree of unsaturation. The initial low methyl ester yield from corn oil compared to soybean and canola oils requires further investigation of the influence of neutralization at the end of the transesterification reaction. To evaluate the neutralization effect with HCl, corn, canola, and soybean oil were transesterified using NaOH at 60 °C with a 6:1 methanol–oil ratio. This research also investigated the effect of reaction times (0.5–1.5 h) with varying neutralization levels (0–100%) on the corn oil methyl ester yield. The yield of corn, canola, and soybean methyl ester was increased significantly by 16–25% through neutralization, indicating the positive impact of neutralization. The corn oil methyl ester yield ranged from 45 to 79% across different neutralization levels and reaction times. With 25% neutralization, the yield increased by 20%. On the other hand, the yield reduced by 18–24% over time when there was no neutralization. A statistical model was developed where the yield varied significantly with the acid amount, reaction time, and their interactions. The quality of the corn methyl ester was found to be within the limits of standard pure methyl ester. Overall, the effect of neutralization showed promise in increasing the yield of quality methyl ester from commercial corn oil. Full article

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10 pages, 4972 KiB

Open AccessCommunication

Heat-Induced Fragmentation and Adhesive Behaviour of Gold Nanowires for Surface-Enhanced Raman Scattering Substrates

by Annamarija Trausa, Ciro Federiko Tipaldi, Liga Ignatane, Boris Polyakov, Sven Oras, Edgars Butanovs, Edgars Vanags and Krisjanis Smits

ChemEngineering 2024, 8(1), 15; https://doi.org/10.3390/chemengineering8010015 - 09 Jan 2024

Cited by 1 | Viewed by 1616

Abstract

This study explores a novel approach to surface-enhanced Raman scattering (SERS) substrate fabrication through the heat-induced fragmentation of gold nanowires (Au NWs) and its impact on gold nanoparticle adhesion/static friction using atomic force microscopy manipulations. Controlled heating experiments and scanning electron microscopy measurements [...] Read more.

This study explores a novel approach to surface-enhanced Raman scattering (SERS) substrate fabrication through the heat-induced fragmentation of gold nanowires (Au NWs) and its impact on gold nanoparticle adhesion/static friction using atomic force microscopy manipulations. Controlled heating experiments and scanning electron microscopy measurements reveal significant structural transformations, with NWs transitioning into nanospheres or nanorods in a patterned fashion at elevated temperatures. These morphological changes lead to enhanced Raman signals, particularly demonstrated in the case of Rhodamine B molecules. The results underscore the critical role of NW shape modifications in augmenting the SERS effect, shedding light on a cost-effective and reliable method for producing SERS substrates. Full article

(This article belongs to the Topic Advances in Chemistry and Chemical Engineering)

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17 pages, 6779 KiB

Open AccessArticle

Oxidation of Allura Red AC Using the NaHCO₃-activated H₂O₂ System Catalyzed with Cobalt Supported on Al-PILC

by Natalia Marín-González, Camila Giraldo-Loaiza, Iván F. Macías-Quiroga, Juan D. Rivera-Giraldo, Julio A. Cardona-Castaño and Nancy R. Sanabria-González

ChemEngineering 2024, 8(1), 14; https://doi.org/10.3390/chemengineering8010014 - 08 Jan 2024

Viewed by 1423

Abstract

The oxidation of aqueous solutions containing Allura Red AC (AR–AC) using bicarbonate-activated peroxide (BAP) and cobalt-impregnated pillared clay (Co/Al–PILC) as the catalyst was investigated. Using the CCD-RMS approach (central composite design–response surface methodology), the effects of dye, H₂O₂, and [...] Read more.

The oxidation of aqueous solutions containing Allura Red AC (AR–AC) using bicarbonate-activated peroxide (BAP) and cobalt-impregnated pillared clay (Co/Al–PILC) as the catalyst was investigated. Using the CCD-RMS approach (central composite design–response surface methodology), the effects of dye, H₂O₂, and NaHCO₃ concentrations on AR–AC degradation were studied. The decolorization, total nitrogen (TN), and total carbon (TC) removals were the analyzed responses, and the experimental data were fitted to empirical quadratic equations for these responses, obtaining coefficients of determination R² and adjusted-R² higher than 0.9528. The multi-objective optimization conditions were [dye] = 21.25 mg/L, [H₂O₂] = 2.59 mM, [NaHCO₃] = 1.25 mM, and a catalyst loading of 2 g/L. Under these conditions, a decolorization greater than 99.43% was obtained, as well as TN and TC removals of 72.82 and 18.74%, respectively, with the added advantage of showing cobalt leaching below 0.01 mg/L. Chromatographic analyses (GC–MS and HPLC) were used to identify some reaction intermediates and by-products. This research showed that wastewater containing azo dyes may be treated using the cobalt-catalyzed BAP system in heterogeneous media. Full article

(This article belongs to the Topic Advances in Chemistry and Chemical Engineering)

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17 pages, 17755 KiB

Open AccessArticle

Evaluation of Ceramic Properties of Bauxitic Materials from SE of Iberian Range

by Domingo Martín, Adolfo Miras, Antonio Romero-Baena, Isabel Guerrero, Joaquín Delgado, Cinta Barba-Brioso, Paloma Campos and Patricia Aparicio

ChemEngineering 2024, 8(1), 13; https://doi.org/10.3390/chemengineering8010013 - 08 Jan 2024

Viewed by 1226

Abstract

The use of aluminum-rich clays and bauxites as refractory materials is common. Upon firing, these materials form mullite crystals in the shape of needles embedded in a siliceous and vitreous matrix, with mullite being responsible for the refractory properties. In this study, bauxite [...] Read more.

The use of aluminum-rich clays and bauxites as refractory materials is common. Upon firing, these materials form mullite crystals in the shape of needles embedded in a siliceous and vitreous matrix, with mullite being responsible for the refractory properties. In this study, bauxite samples for use in refractory applications have been characterized. Chemical analysis revealed that the alumina content varied between 34 and 40%, with silica values generally being high (around 40%), except for one sample (26%). Two samples were found to be the most suitable for use as “refractory clay” refractories. However, high silica or Fe oxide contents can affect mineralogical transformations at high temperatures. Mineralogical analysis confirmed the presence of several minerals in the bauxite materials, including kaolinite, halloysite, anatase, rutile, gibbsite and boehmite. Differential thermal analysis (DTA) showed the decomposition of gibbsite and its partial transformation to boehmite and alumina, and the dehydroxylation of kaolinite, with primary mullite crystallization observed at a high temperature. These findings provide valuable information for the selection and optimization of bauxite materials for refractory applications, considering their chemical composition and mineralogical characteristics. Full article

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11 pages, 1020 KiB

Open AccessArticle

Different Substrate Selectivity and Product Patterns of Immobilized Thermophilic Lipases from Geobacillus stearothermophilus, Anoxybacillus flavithermus, and Thermomyces lanuginosus for Glyceryl Decanoate Synthesis

by Teif A. Najm, Marie K. Walsh and Namhyeon Park

ChemEngineering 2024, 8(1), 12; https://doi.org/10.3390/chemengineering8010012 - 05 Jan 2024

Viewed by 1250

Abstract

Lipases can catalyze synthesis reactions in a micro aqueous system, producing useful partial glycerides (mono- and diglycerides), and these compounds are commonly utilized in different products as surfactants. Depending on the microbial sources for lipases, immobilization conditions, and starting substrates for synthesis reaction, [...] Read more.

Lipases can catalyze synthesis reactions in a micro aqueous system, producing useful partial glycerides (mono- and diglycerides), and these compounds are commonly utilized in different products as surfactants. Depending on the microbial sources for lipases, immobilization conditions, and starting substrates for synthesis reaction, the composition and yields of the resulting partial glycerides could be variable. These differences could lead to the final efficacy of partial glycerides as surfactants in targeted products. Therefore, it is necessary to establish a group of immobilized lipases from different microbial sources with information about substrate specificity to produce effective partial glycerides for various product types. Here, lipases from thermophilic Geobacillus stearothermophilus and Anoxybacillus flavithermus were prepared with a simple partial purification method, and after immobilization, these lipases were tested to synthesize partial glycerides using different types of decanoic acids. The distinct product patterns were analyzed using HPLC. Both immobilized lipases showed the highest substrate selectivity to decanoic acids in common, producing mainly glyceryl monodecanoate. However, commercial immobilized lipases from Thermomyces lanuginosus produced the largest glyceryl monodecanoate from methyl decanoate. These results indicate the importance of immobilization conditions like different microbial sources and substrates and the need for their optimal combination. Full article

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14 pages, 1130 KiB

Open AccessArticle

Sequential Extraction of Carbohydrates and Lipids from Chlorella vulgaris Using Combined Physical and Chemical Pre-Treatments

by William Hammann, Andrew Ross and Wayne Seames

ChemEngineering 2024, 8(1), 11; https://doi.org/10.3390/chemengineering8010011 - 05 Jan 2024

Viewed by 1583

Abstract

A key focus of microalgae-based fuels/chemicals research and development has been on the lipids that many strains generate, but recent studies show that solely recovering these lipids may not be cost competitive with fossil-derived processes. However, if the carbohydrates can also be recovered [...] Read more.

A key focus of microalgae-based fuels/chemicals research and development has been on the lipids that many strains generate, but recent studies show that solely recovering these lipids may not be cost competitive with fossil-derived processes. However, if the carbohydrates can also be recovered and ultimately converted into useful chemical intermediates, this may improve the economics for microalgae-based sustainable product technologies. In the present work, physical and chemical pre-treatments were performed on the Chlorella vulgaris microalgae strain to recover the carbohydrates from the biomass primarily in the form of glucose and galactose. The effects of temperature, acid concentration, microalgae solid-to-liquid loading, and hydrolysis time on carbohydrate hydrolysis and recovery was explored to identify optimum conditions. The highest recovery of total carbohydrates, 90 ± 1.1 wt% at 95% confidence which represents 40 wt% of the initial biomass, was obtained using temperature-assisted weak-acid extraction. Sequential extraction of carbohydrates and lipids was then explored. The highest recovery of total lipids was 71 ± 1.8 wt%, which represents 22 ± 0.9 wt% of the initial biomass. The sequential extraction of carbohydrates followed by lipids resulted in an overall recovery of 60 ± 1.6 wt% of the initial biomass, which is higher than current single product recovery strategies. These results suggest that adding carbohydrate recovery may be a viable strategy for overcoming a major economic hurdle to microalgae-derived chemical and fuel production by significantly increasing the yield of usable materials from microalgae biomass. Full article

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

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11 pages, 1445 KiB

Open AccessArticle

Simulation Process for Allyl Alcohol Production via Deoxydehydration of Glycerol

by Ghadir Assaad, Karen Silva Vargas, Benjamin Katryniok and Marcia Araque

ChemEngineering 2024, 8(1), 10; https://doi.org/10.3390/chemengineering8010010 - 03 Jan 2024

Viewed by 1617

Abstract

A process for the deoxydehydration (DODH) of glycerol to allyl alcohol in 2-hexanol as solvent was modelled with Aspen Plus. Experimental results for the DODH reaction, the liquid vapour equilibria and the catalytic hydrogenation were employed for the development of the model. The [...] Read more.

A process for the deoxydehydration (DODH) of glycerol to allyl alcohol in 2-hexanol as solvent was modelled with Aspen Plus. Experimental results for the DODH reaction, the liquid vapour equilibria and the catalytic hydrogenation were employed for the development of the model. The whole process consists of four subsystems: allyl alcohol production (S1), solvent recovery (S2), allyl alcohol purification (S3) and solvent regeneration (S4). Based on the results of the process model, allyl alcohol with 96% yield and a purity of 99.99% with product loss of only 0.2% was obtained. The optimisation of the energy consumption through an integrated heat exchange network resulted in a net primary energy input of 863.5 kW, which corresponded to a carbon footprint of 1.89 kgCO₂/kgAllylOH. Full article

(This article belongs to the Collection Green and Environmentally Sustainable Chemical Processes)

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16 pages, 2261 KiB

Open AccessArticle

Nano-Iron Oxide Coating for Enhanced Heat Transfer in Gas–Solid Fluidized Bed Systems

by Fadhl H. Faraj, Jamal M. Ali, Sarmad T. Najim, Abbas J. Sultan, Saja M. Alardhi and Hasan Sh. Majdi

ChemEngineering 2024, 8(1), 9; https://doi.org/10.3390/chemengineering8010009 - 02 Jan 2024

Viewed by 1330

Abstract

This study explores using iron oxide coatings on glass beads to improve heat transfer efficiency in fluidized bed reactors. Techniques such as BET surface area analysis, SEM imaging, and X-ray diffraction were used to characterize the coated beads. Results showed the successful creation [...] Read more.

This study explores using iron oxide coatings on glass beads to improve heat transfer efficiency in fluidized bed reactors. Techniques such as BET surface area analysis, SEM imaging, and X-ray diffraction were used to characterize the coated beads. Results showed the successful creation of a crystalline iron layer on the beads’ surface and increased thermal conductivity, especially at elevated temperatures. The study also quantified the impact of air surface velocity and heating power on the heat transfer coefficient, revealing substantial improvements, especially at higher velocities. It was found that the heat transfer coefficient for 600 µm glass beads increases significantly from 336.4 W/m²·K to 390.3 W/m²·K when the velocity is 0.27 m/s and the heating flux is 125 W. This demonstrates the effectiveness of the iron oxide coating in improving heat transfer. The results of this study emphasize the efficacy of iron oxide coatings in augmenting heat transmission characteristics, particularly in fluidized bed reactor. Full article

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19 pages, 7994 KiB

Open AccessArticle

Catalysts Based on Iron Oxides for Wastewater Purification from Phenolic Compounds: Synthesis, Physicochemical Analysis, Determination of Catalytic Activity

by Binara T. Dossumova, Larissa R. Sassykova, Tatyana V. Shakiyeva, Dinara Muktaly, Aigul A. Batyrbayeva and Madina A. Kozhaisakova

ChemEngineering 2024, 8(1), 8; https://doi.org/10.3390/chemengineering8010008 - 01 Jan 2024

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Abstract

In this work, the synthesis of magnetite nanoparticles and catalysts based on it stabilized with silicon and aluminum oxides was carried out. It is revealed that the stabilization of the magnetite surface by using aluminum and silicon oxides leads to a decrease in [...] Read more.

In this work, the synthesis of magnetite nanoparticles and catalysts based on it stabilized with silicon and aluminum oxides was carried out. It is revealed that the stabilization of the magnetite surface by using aluminum and silicon oxides leads to a decrease in the size of magnetite nanocrystals in nanocomposites (particle diameter less than ~10 nm). The catalytic activity of the obtained catalysts was evaluated during the oxidation reaction of phenol, pyrocatechin and cresol with oxygen. It is well known that phenolic compounds are among the most dangerous water pollutants. The effect of phenol concentration and the effect of temperature (303–333 K) on the rate of oxidation of phenol to Fe₃O₄/SiO₂ has been studied. It has been determined that the dependence of the oxidation rate of phenol on the initial concentration of phenol in solution is described by a first-order equation. At temperatures of 303–313 K, incomplete absorption of the calculated amount of oxygen is observed, and the analysis data indicate the non-selective oxidation of phenol. Intermediate products, such as catechin, hydroquinone, formic acid, oxidation products, were found. The results of UV and IR spectroscopy showed that catalysts based on magnetite Fe₃O₄ are effective in the oxidation of phenol with oxygen. In the UV spectrum of the product in the wavelength range 190–1100 nm, there is an absorption band at a wavelength of 240–245 nm and a weak band at 430 nm, which is characteristic of benzoquinone. In the IR spectrum of the product, absorption bands were detected in the region of 1644 cm⁻¹, which is characteristic of the oscillations of the C=O bonds of the carbonyl group of benzoquinone. The peaks also found at 1353 cm⁻¹ and 1229 cm⁻¹ may be due to vibrations of the C-H and C-C bonds of the quinone ring. It was found that among the synthesized catalysts, the Fe₃O₄/SiO₂ catalyst demonstrated the greatest activity in the reaction of liquid-phase oxidation of phenol. Full article

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22 pages, 12388 KiB

Open AccessArticle

Effect of Inserting Baffles on the Solid Particle Segregation Behavior in Fluidized Bed Reactor: A Computational Study

by Suchart Kreesaeng, Benjapon Chalermsinsuwan and Pornpote Piumsomboon

ChemEngineering 2024, 8(1), 7; https://doi.org/10.3390/chemengineering8010007 - 01 Jan 2024

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Abstract

In multi-solid, particle-size fluidized bed reactor systems, segregation is commonly observed. When segregation occurred, small solid particles were entrained to the top of the bed and escaped from the reactor. During the combustion process, the small solid particles that escaped from the boiler [...] Read more.

In multi-solid, particle-size fluidized bed reactor systems, segregation is commonly observed. When segregation occurred, small solid particles were entrained to the top of the bed and escaped from the reactor. During the combustion process, the small solid particles that escaped from the boiler were burned and subjected to damage around the cyclone separator. This study then employed a computational fluid dynamics approach to investigate solid particle behavior in the reactor using three different sizes of solid particles. The effects of baffle insertion, baffle angle, stage number, and its arrangement were examined. The percentage of segregation was calculated to compare behavior among different reactor systems. The insertion of 45-degree baffles resulted in reduced segregation behavior compared to cases without baffles and with 90-degree baffles, attributed to solid hindering and collision phenomena. Additionally, a double-stage baffle with any arrangement could reduce segregation behavior. The best arrangement was “above-arrangement” due to particles hindering, swirling, and accumulating between the baffle stages. Therefore, to diminish segregation behavior and enhance combustion chemical reactions, the insertion of baffles in the reactor zone is recommended. Full article

(This article belongs to the Topic Advances in Chemistry and Chemical Engineering)

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13 pages, 2349 KiB

Open AccessArticle

Force Field for Calculation of the Vapor-Liquid Phase Equilibrium of trans-Decalin

by Ivan P. Anashkin and Alexander V. Klinov

ChemEngineering 2024, 8(1), 6; https://doi.org/10.3390/chemengineering8010006 - 26 Dec 2023

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Abstract

Based on the TraPPE force field, previously unknown values of the parameters of the intermolecular interaction potential of trans-decalin were determined. Parametrization was carried out using experimental data on saturated vapor pressure and density at atmospheric pressure. The found parameters make it [...] Read more.

Based on the TraPPE force field, previously unknown values of the parameters of the intermolecular interaction potential of trans-decalin were determined. Parametrization was carried out using experimental data on saturated vapor pressure and density at atmospheric pressure. The found parameters make it possible to adequately describe the boiling and condensation lines of trans-decalin and also predict the critical values of pressure, density, and temperature with satisfactory accuracy. Calculations of vapor-liquid phase equilibrium conditions for a binary CO₂—trans-decalin mixture in supercritical conditions for CO₂ were carried out. When quantitatively comparing the calculated values with experimental data, an underestimation of pressure at a temperature of 345.4 K by 30% is observed, which decreases to 5% for temperatures up to 525 K. Full article

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14 pages, 4498 KiB

Open AccessArticle

Numerical Simulation of a Valorisation-Oriented Hybrid Process for the Bio-Oil-Related Separation of Acetol and Acetic Acid

by Chavdar Chilev, Farida Lamari and Patrick Langlois

ChemEngineering 2024, 8(1), 5; https://doi.org/10.3390/chemengineering8010005 - 22 Dec 2023

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Abstract

Biomass as a whole offers a more diverse potential for valorisation than any other renewable energy source. As one of the stages in the separation of bio-oil involves a liquid mixture of acetol and acetic acid, and as both components are particularly well [...] Read more.

Biomass as a whole offers a more diverse potential for valorisation than any other renewable energy source. As one of the stages in the separation of bio-oil involves a liquid mixture of acetol and acetic acid, and as both components are particularly well suited for valorisation, a hybrid method was developed for their separation with a high purity level through an approach combining liquid–liquid extraction and distillation. In order to design and simulate the flowsheet, the ChemCAD 7.0 simulation software was used. Sensitivity analyses were carried out to investigate the influence of the different parameters in the distillation columns, such as the reflux ratio, the feed stage location, and the vapour/bottom molar flow ratio. The effect of different extractants and of their excess on the separation process, as well as the possibility of regenerating the extractant, was also studied. Tri-n-octylamine was accordingly selected as a separating agent that was fully recycled. The end result for separating an initial 48/52 wt% acetol/acetic acid liquid mixture was acetol with a purity of 99.4 wt% and acetic acid with a purity of 100 wt%. Full article

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

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12 pages, 4287 KiB

Open AccessArticle

Antisolvent Crystallization of Papain

by Sasitorn Boonkerd and Lek Wantha

ChemEngineering 2024, 8(1), 4; https://doi.org/10.3390/chemengineering8010004 - 20 Dec 2023

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Abstract

Protein crystallization plays a crucial role in the food and pharmaceutical industries, enhancing product quality and efficiency by improving purity and controlled particle characteristics. This study focused on the crystallization of the versatile protein papain, extracted from papaya. Antisolvent crystallization was performed. This [...] Read more.

Protein crystallization plays a crucial role in the food and pharmaceutical industries, enhancing product quality and efficiency by improving purity and controlled particle characteristics. This study focused on the crystallization of the versatile protein papain, extracted from papaya. Antisolvent crystallization was performed. This method is cost-effective and is a simple and energy-efficient approach. Beyond protein crystal production, the antisolvent crystallization process serves as a method for encapsulating active pharmaceutical ingredients (APIs). The study investigated organic solvents like ethanol, acetone, and acetonitrile as potential antisolvents. Additionally, the impact of variables such as the solvent-to-antisolvent (S:AS) volume ratio and papain concentration on particle size, particle size distribution, zeta potential, crystallization yield, and residual activity of papain crystals were examined. Ethanol emerged as the optimal antisolvent, reducing the solubility of papain and preserving papain’s crystalline structure with minimal activity loss. Optimal conditions were identified at a 1:4 S:AS volume ratio and a papain concentration of 30 mg/mL, resulting in nanosized spherical crystals with a high yield and preserved activity. This research underscored the crucial role of thoughtful parameter selection in antisolvent crystallization to achieve specific particle characteristics while maintaining the functionality of the crystallized substance. Full article

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12 pages, 1859 KiB

Open AccessCommunication

Ultrafiltration to Increase the Consistency of Fruit Pulps: The Role of Permeate Flux

by Fulvia Chiampo

ChemEngineering 2024, 8(1), 3; https://doi.org/10.3390/chemengineering8010003 - 20 Dec 2023

Viewed by 1140

Abstract

Ultrafiltration is a well-known operation, widely used in food processing, especially to concentrate selectively liquid compounds. However, so far, it has been mainly used to change concentration and/or clarify liquids with low viscosity. Ultrafiltration has seldomly been applied to viscous fluids. In this [...] Read more.

Ultrafiltration is a well-known operation, widely used in food processing, especially to concentrate selectively liquid compounds. However, so far, it has been mainly used to change concentration and/or clarify liquids with low viscosity. Ultrafiltration has seldomly been applied to viscous fluids. In this study, it was used to increase the consistency of fruit pulps, without changing their taste and organoleptic properties. This paper reports the findings achieved in experimental runs carried out on a pilot plant, equipped with four ultrafiltration tubular membranes (total surface area = 0.8 m²). Raw fruit pulps, namely, apple, apricot, and pear, were used to study the influence of the operative parameters on the permeate flux and organoleptic properties of the final products (retentate and permeate). The flow rate was in the range of 3.0–5.1 m³/h, at 50 °C. The influence of temperature on the permeate flux was checked, with one run with apple pulp at 20 °C. As expected, the findings show that high flow rate and temperature improve the permeate flux. Membranes show different performance in permeate flux for the tested pulps. This is probably due to their different chemical and physical composition, which could be responsible for different fouling of the membrane and, as a consequence, a different resistance to the permeate flow. The final products have the same taste as the raw ones, and each of them can be used as it is or as an ingredient. These results have a technological relevance, and, besides, the study shows a methodology for future applications of ultrafiltration. Full article

(This article belongs to the Special Issue State-of-the-Art Membrane Technologies in Chemical Engineering)

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15 pages, 6399 KiB

Open AccessArticle

Significant Progress of Initiated Chemical Vapor Deposition in Manufacturing Soft Non-spherical Nanoparticles: Upgrading to the Condensed Droplet Polymerization Approach and Key Technological Aspects

by Di Zhang

ChemEngineering 2024, 8(1), 2; https://doi.org/10.3390/chemengineering8010002 - 19 Dec 2023

Viewed by 1493

Abstract

Initiated chemical vapor deposition is a unique solvent-free and completely dry vapor-phase deposition technique used to synthesize organic polymer films. In this process, an activated initiator, monomer, and carrier gas are introduced into the reaction chamber simultaneously. This technique has been widely adopted. [...] Read more.

Initiated chemical vapor deposition is a unique solvent-free and completely dry vapor-phase deposition technique used to synthesize organic polymer films. In this process, an activated initiator, monomer, and carrier gas are introduced into the reaction chamber simultaneously. This technique has been widely adopted. However, if the monomer and initiator are introduced into the chamber in stages—allowing gas-phase monomer deposition and condensation first, followed by initiator introduction and controlling the monomer partial pressure to be higher than the saturated vapor pressure—non-spherical polymer nanoparticles with dome-like shapes can be obtained. This advanced iCVD technique is referred to as the “Condensed Droplet Polymerization Approach”. This high monomer partial pressure gas-phase deposition is not suitable for forming uniformly composed iCVD films; but interestingly, it can rapidly obtain polymer nanodomes (PNDs). Using CDP technology, Franklin polymerized multifunctional nanodomes in less than 45 s, demonstrating a wide range of continuous particle size variations, from sub-20 nanometers to over 1 micron. This rapid synthesis included a variety of functional polymer nanodomes in just a matter of seconds to minutes. This review discusses the crucial process conditions of the Condensed Droplet Polymerization (CDP) Approach for synthesizing PNDs. The main focus of the discussion was on the two-step method for synthesizing PNDs, where the nucleation mechanism of PNDs, factors influencing their size, and the effect of pressure on the distinct condensation of monomer vapor into polymer nanodomes and polymer films were extensively explored. Full article

(This article belongs to the Topic Advances in Chemistry and Chemical Engineering)

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28 pages, 1620 KiB

Open AccessArticle

Improved Fault Detection in Chemical Engineering Processes via Non-Parametric Kolmogorov–Smirnov-Based Monitoring Strategy

by K. Ramakrishna Kini, Muddu Madakyaru, Fouzi Harrou, Mukund Kumar Menon and Ying Sun

ChemEngineering 2024, 8(1), 1; https://doi.org/10.3390/chemengineering8010001 - 19 Dec 2023

Cited by 1 | Viewed by 1323

Abstract

Fault detection is crucial in maintaining reliability, safety, and consistent product quality in chemical engineering processes. Accurate fault detection allows for identifying anomalies, signaling deviations from the system’s nominal behavior, ensuring the system operates within desired performance parameters, and minimizing potential losses. This [...] Read more.

Fault detection is crucial in maintaining reliability, safety, and consistent product quality in chemical engineering processes. Accurate fault detection allows for identifying anomalies, signaling deviations from the system’s nominal behavior, ensuring the system operates within desired performance parameters, and minimizing potential losses. This paper presents a novel semi-supervised data-based monitoring technique for fault detection in multivariate processes. To this end, the proposed approach merges the capabilities of Principal Component Analysis (PCA) for dimensionality reduction and feature extraction with the Kolmogorov–Smirnov (KS)-based scheme for fault detection. The KS indicator is computed between the two distributions in a moving window of fixed length, allowing it to capture sensitive details that enhance the detection of faults. Moreover, no labeling is required when using this fault detection approach, making it flexible in practice. The performance of the proposed PCA–KS strategy is assessed for different sensor faults on benchmark processes, specifically the Plug Flow Reactor (PFR) process and the benchmark Tennessee Eastman (TE) process. Different sensor faults, including bias, intermittent, and aging faults, are considered in this study to evaluate the proposed fault detection scheme. The results demonstrate that the proposed approach surpasses traditional PCA-based methods. Specifically, when applied to PFR data, it achieves a high average detection rate of 98.31% and a low false alarm rate of 0.25%. Similarly, when applied to the TE process, it provides a good average detection rate of 97.27% and a false alarm rate of 6.32%. These results underscore the efficacy of the proposed PCA–KS approach in enhancing the fault detection of high-dimensional processes. Full article

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ChemEngineering, Volume 8, Issue 1 (February 2024) – 25 articles

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