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18 pages, 3754 KiB

Open AccessArticle

N, S-Doped Carbon Dots (N, S-CDs) for Perfluorooctane Sulfonic Acid (PFOS) Detection

by Hani Nasser Abdelhamid

C 2025, 11(2), 36; https://doi.org/10.3390/c11020036 - 29 May 2025

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Nitrogen and sulfur-co-doped carbon dots (N, S-CDs) were synthesized using a simple, eco-friendly hydrothermal technique with L-cysteine as the precursor. The synthesis approach produced highly water-dispersible, heteroatom-doped CDs with surface functional groups comprising amine, carboxyl, thiol, and sulfonic acid. Data analysis of X-ray [...] Read more.

Nitrogen and sulfur-co-doped carbon dots (N, S-CDs) were synthesized using a simple, eco-friendly hydrothermal technique with L-cysteine as the precursor. The synthesis approach produced highly water-dispersible, heteroatom-doped CDs with surface functional groups comprising amine, carboxyl, thiol, and sulfonic acid. Data analysis of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM) confirmed their amorphous nature, nanoscale dimensions (1–8 nm, average particle size of 2.6 nm), and surface chemistry. Optical examination revealed intense and pure blue fluorescence emission under UV excitation, with excitation-dependent emission behavior attributed to surface defects and heteroatom doping. The N, S-CDs were applied as fluorescent probes for detecting perfluorooctanesulfonic acid (PFOS), a notable component of the perfluoroalkyl substances (PFAS) family, demonstrating pronounced and concentration-dependent fluorescence quenching. A linear detection range of 3.33–20 µM and a limit of detection (LOD) of 2 µM were reported using the N, S-CDs probe. UV-Vis spectral shifts and dye-interaction investigations indicated that the sensing mechanism is regulated by non-covalent interactions, primarily electrostatic and hydrophobic forces. These findings confirm the potential of N, S-CDs to be used as effective optical sensors for detecting PFOS in environmental monitoring applications. Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application (2nd Edition))

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47 pages, 2999 KiB

Open AccessReview

Advances in the Synthesis of Carbon Nanomaterials Towards Their Application in Biomedical Engineering and Medicine

by Numair Elahi and Constantinos D. Zeinalipour-Yazdi

C 2025, 11(2), 35; https://doi.org/10.3390/c11020035 - 20 May 2025

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Abstract

Carbon nanomaterials that include different forms such as graphene, carbon nanotubes, fullerenes, graphite, nanodiamonds, carbon nanocones, amorphous carbon, as well as porous carbon, are quite distinguished by their unique structural, electrical, and mechanical properties. This plays a major role in making them pivotal [...] Read more.

Carbon nanomaterials that include different forms such as graphene, carbon nanotubes, fullerenes, graphite, nanodiamonds, carbon nanocones, amorphous carbon, as well as porous carbon, are quite distinguished by their unique structural, electrical, and mechanical properties. This plays a major role in making them pivotal in various medical applications. The synthesis methods used for such nanomaterials, including techniques such as chemical vapor deposition (CVD), arc discharge, laser ablation, and plasma-enhanced chemical vapor deposition (PECVD), are able to offer very precise control over material purity, particle size, and scalability, enabling for nanomaterials catered for different specific applications. These materials have been explored in a range of different systems, which include drug-delivery systems, biosensors, tissue engineering, as well as advanced imaging techniques such as MRI and fluorescence imaging. Recent advancements, including green synthesis strategies and novel innovative approaches like ultrasonic cavitation, have improved both the precision as well as the scalability of carbon nanomaterial production. Despite challenges like biocompatibility and environmental concerns, these nanomaterials hold immense promise in revolutionizing personalized medicine, diagnostics, and regenerative therapies. Many of these applications are currently positioned at Technology Readiness Levels (TRLs) 3–4, with some systems advancing toward preclinical validation, highlighting their emerging translational potential in clinical settings. This review is specific in evaluating synthesis techniques of different carbon nanomaterials and establishing their modified properties for use in biomedicine. It focuses on how these techniques establish biocompatibility, scalability, and performance for use in medicines such as drug delivery, imaging, and tissue engineering. The implications of nanostructure behavior in biological environments are further discussed, with emphasis on applications in imaging, drug delivery, and biosensing. Full article

(This article belongs to the Special Issue Carbon Nanohybrids for Biomedical Applications (2nd Edition))

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21 pages, 1460 KiB

Open AccessArticle

The Application of a Multidisciplinary Framework for Optimizing the Monitoring System for Geological CO₂ Storage

by Yngve Heggelund, Martha Lien and Danny Otto

C 2025, 11(2), 34; https://doi.org/10.3390/c11020034 - 17 May 2025

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Abstract

The technical objective of a monitoring system is to provide the means to detect potential irregularities related to the project plan, to provide assurance that the migration of the CO₂ plume stays within the storage unit, and to show that CO₂ [...] Read more.

The technical objective of a monitoring system is to provide the means to detect potential irregularities related to the project plan, to provide assurance that the migration of the CO₂ plume stays within the storage unit, and to show that CO₂ behaves in conformance with the model predictions. From an operational point of view, monitoring will also provide data that can be used to optimize the injection schedule relative to the storage capacity and availability of CO₂ to minimize risks and long-term costs. Finally, monitoring is a crucial factor for the public perception of risks related to CO₂ storage, as surveys indicate that adequately designed monitoring can mitigate concerns. The Analytical Hierarchy Process (AHP) is a holistic, transdisciplinary, multi-criteria decision-making framework. The objective of this work is to apply the AHP framework to monitoring-solutions for a synthetic geological storage site of CO₂ to secure the technical, operational, and societal embeddedness of the solutions and gain experience in how this can be applied to a real project. Through this first application of AHP within the field of geological carbon storage, the AHP was found to be a structured and transparent framework for holistic, multi-criteria decision-making (MCDM), where the wisdom and expertise of different domain experts were considered. A further novelty in this study is introducing a measure of spread in assessing the various solution alternatives’ capacity to meet monitoring criteria. This approach was utilized to underscore disparities among respondents’ experiences and to identify potential informational deficiencies in evaluating alternatives and devising the optimal monitoring solution. Full article

(This article belongs to the Section Carbon Cycle, Capture and Storage)

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10 pages, 3906 KiB

Open AccessArticle

Graphite-like C₃N₄ and Graphene Oxide Co-Enhanced the Photocatalytic Activity of ZnO Under Natural Sunlight

by Huan Chen, Shengfeng Chen, Qun Fang and Chuansheng Chen

C 2025, 11(2), 33; https://doi.org/10.3390/c11020033 - 6 May 2025

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Abstract

To enhance the photocatalytic performance of ZnO, the ZnO/g-C₃N₄ (ZCN) composite was prepared by ZnO and g-C₃N₄ under ball milling, and then the ternary graphene oxide (GO)/ZnO/g-C₃N₄ (GZCN) composite was achieved by using sonicating, [...] Read more.

To enhance the photocatalytic performance of ZnO, the ZnO/g-C₃N₄ (ZCN) composite was prepared by ZnO and g-C₃N₄ under ball milling, and then the ternary graphene oxide (GO)/ZnO/g-C₃N₄ (GZCN) composite was achieved by using sonicating, stirring, and liquid phase evaporating. The photocatalytic performance was tested under UV light and natural solar light, respectively. The experimental results displayed that the GZCN composite revealed excellent photocatalytic performance under UV light and natural sunlight. When the ratio of ZnO to g-C₃N₄ is 1:0.2 and the mass fraction of graphene oxide is 0.25% in GZCN composite, the modified ZnO possesses optimal photocatalytic activity under UV light or natural solar light. RhB dye is degraded by 94% within 20 min under UV light, which is 3.41 times that of pure ZnO. Moreover, GZCN can degrade 88% of RhB in 60 min under natural sunlight. The enhancement for photocatalytic activity is attributed to the excellent conductivity of GO and heterojunction interaction between ZnO and g-C₃N₄, where the special electronic structure of g-C₃N₄ expands the spectral response range of ZnO and accelerates the transmission of photogenerated electrons and holes. Full article

(This article belongs to the Special Issue Advanced Graphene and g-C3N4-Based Photocatalysts for Energy Conversion)

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13 pages, 2893 KiB

Open AccessArticle

Fabrication of Wood-Derived Carbon Aerogel/Mg(OH)₂ Bio-Composite and Its High Performance for Adsorption and Separation of Cadmium Ions

by Ran An, Jinyue Liu, Haomiao Ma, Yuqing Yan, Yuanru Guo, Qingjiang Pan and Shujun Li

C 2025, 11(2), 32; https://doi.org/10.3390/c11020032 - 6 May 2025

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Abstract

To address the need for reducing carbon emissions and enhancing the sustainable utilization of non-fossil resources, a one-step calcination strategy has been developed to fabricate hierarchical carbon aerogels from balsa wood. The resulting wood-derived carbon aerogels (WCA) were functionalized with Mg(OH)₂ to [...] Read more.

To address the need for reducing carbon emissions and enhancing the sustainable utilization of non-fossil resources, a one-step calcination strategy has been developed to fabricate hierarchical carbon aerogels from balsa wood. The resulting wood-derived carbon aerogels (WCA) were functionalized with Mg(OH)₂ to boost their environmental remediation potential. Comprehensive characterization using XRD, FT-IR, XPS, and SEM confirmed that the optimized WCA/Mg(OH)₂ composite (WCAMg) retained a three-dimensional hierarchical porous structure, and Mg(OH)₂ nanosheets were attached to it. The adsorption performance of WCAMg composites towards Cd²⁺ was systematically investigated through controlled experiments, which focused on three critical variables (Mg(OH)₂ loading content, initial Cd²⁺ concentration and solution ionic strength). The functionalized WCAMg demonstrated a maximum Cd²⁺ adsorption capacity of 351.1 mg g⁻¹—a tenfold improvement over pristine WCA. Combined with exceptional adsorption efficiency, this biomass-derived composite offers an eco-friendly, cost-effective solution for heavy metal ion remediation. Its scalable fabrication from renewable resources aligns with sustainable water treatment objectives, presenting the advantage of pollution mitigation. Full article

(This article belongs to the Special Issue Carbon-Based Materials Applied in Water and Wastewater Treatment)

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11 pages, 4734 KiB

Open AccessArticle

Electron Beam-Irradiated Cross-Linked Polyethylene Composites Containing Graphene Nanoplatelets for Thermally Conducting Pipes

by Wenge Xu, Kuan Lu, Huinan Li, Chen Xiong, Yang Liu and Baijun Liu

C 2025, 11(2), 31; https://doi.org/10.3390/c11020031 - 4 May 2025

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Abstract

In this study, some polyethylene/graphene nanoplatelet (PE-GE) composites are successfully prepared via a melt-blending process used for thermally conductive pipes. A comparison study on the effect of different fillers (i.e., graphene nanoplatelet and aluminum oxide) on thermal conductivity is conducted. The conductivity was [...] Read more.

In this study, some polyethylene/graphene nanoplatelet (PE-GE) composites are successfully prepared via a melt-blending process used for thermally conductive pipes. A comparison study on the effect of different fillers (i.e., graphene nanoplatelet and aluminum oxide) on thermal conductivity is conducted. The conductivity was over 2.5 W/m·K when 30 fractions of GE were involved. Furthermore, an electron beam irradiation technology is utilized to obtain the cross-linked composite materials with excellent comprehensive performance. The relationships between thermal conductivity and filler content, and irradiation dose and gel content have been carefully investigated. Finally, a polyethylene/graphene composite with 0.72 W/m·K is used to extrude a pipe, which exhibits some attractive properties for floor heating pipes. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Composites: Synthesis, Processing, Characterization and Applications)

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19 pages, 3581 KiB

Open AccessArticle

Innovative X-Ray Absorption Technology for Improved Monitoring of the Degradation and Oxidation of Granular Activated Carbon Filters Used in Hospital Water Treatment Systems

by Jeamichel Puente Torres, Harold Crespo Sariol, Thayset Mariño Peacok, Tom Haeldermans, Guy Reggers, Jan Yperman, Peter Adriaensens, Robert Carleer and Dries Vandamme

C 2025, 11(2), 30; https://doi.org/10.3390/c11020030 - 28 Apr 2025

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Abstract

This study introduces a novel, non-invasive X-ray absorption analysis (XRA) method to evaluate the photonic absorption process of granular activated carbon (GAC) in hospital water purification systems. By leveraging digital radiographic images, this innovative technique monitors the deterioration and oxidation of the GAC [...] Read more.

This study introduces a novel, non-invasive X-ray absorption analysis (XRA) method to evaluate the photonic absorption process of granular activated carbon (GAC) in hospital water purification systems. By leveraging digital radiographic images, this innovative technique monitors the deterioration and oxidation of the GAC filter, predicts its remaining lifetime, and estimates its water dechlorinating capacity. Analyzing the entire GAC filter and making a reuse possible, the new XRA method provides valuable insights into the filter’s condition, enhancing water purification efficiency and costs without analyzing subsamples. Complementary analytical techniques on subsamples, taken at various depths, did not yield valuable additional information of the GAC filter exhaustion condition, nor additionally make a reuse impossible. Full article

(This article belongs to the Special Issue Carbon-Based Materials Applied in Water and Wastewater Treatment)

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16 pages, 4882 KiB

Open AccessArticle

Experimental Investigation of Use of Monoethanolamine with Iron Oxide Nanoparticles in a 10 kg per Day Pilot CO₂ Capture Plant: Implications for Commercialization

by Sriniwasa Prabhu, Govindaradjane Soupramaniane and Raman Saravanane

C 2025, 11(2), 29; https://doi.org/10.3390/c11020029 - 27 Apr 2025

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Abstract

This study explores enhancements in CO₂ capture and release using monoethanolamine (MEA) combined with iron oxide nanoarticles (IONPs) in a 10 kg per day pilot CO₂ capture plant. Previous studies highlighted the potential of nanoparticle additives to improve CO₂ capture [...] Read more.

This study explores enhancements in CO₂ capture and release using monoethanolamine (MEA) combined with iron oxide nanoarticles (IONPs) in a 10 kg per day pilot CO₂ capture plant. Previous studies highlighted the potential of nanoparticle additives to improve CO₂ capture via modeling and batch experiments; however, robust experimental evidence at the pilot scale is necessary for commercialization. This pilot plant employed a thermal swing process using synthetic CO₂–flue gas mixtures, conditioning systems, and Programmable Logic Controller (PLC)-based controls for heating, operation, and data acquisition. IONPs, synthesized through chemical precipitation and characterized by XRD and HR-SEM, were integrated into MEA at concentrations of 0.0001% w/v (1 ppm), 0.001% w/v (10 ppm), and 0.002% w/v (20 ppm). Their electromagnetic properties enhanced mass transfer during absorption and significantly reduced heat demand during stripper desorption. Higher concentrations of IONPs decreased desorption temperatures by up to 7 °C, resulting in estimated energy savings of approximately 10–15%, while achieving CO₂ loading rates up to 0.34 mol CO₂/mol MEA. Structural stability of the IONPs was confirmed via XRD and HR-SEM analyses following extended thermal cycling. Utilizing a common solvent and abundant catalyst, these demonstrated improvements underscore the practical scalability and commercial viability of MEA-based CO₂ capture catalyzed by IONPs, particularly suitable for deployment in large-scale CO₂ capture systems in high-CO₂-emitting industries. Full article

(This article belongs to the Section Carbon Cycle, Capture and Storage)

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28 pages, 4940 KiB

Open AccessReview

Plasma-Modified Carbon Materials for Radionuclide Absorption

by Yifan Fang, Zixuan Guo, Bing Lian, Jing Kang, Zhou Fang, Longfei Qie, Lili Liu, Luxiang Zhao and Ruixue Wang

C 2025, 11(2), 28; https://doi.org/10.3390/c11020028 - 22 Apr 2025

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Abstract

Carbon-based materials, characterized by their high specific surface area and exceptional chemical stability, have become integral to adsorption-based remediation methods. Carbon materials demonstrate exceptional efficiency, selectivity, and environmental compatibility in radionuclide adsorption. However, the practical application of conventional carbon materials is limited by [...] Read more.

Carbon-based materials, characterized by their high specific surface area and exceptional chemical stability, have become integral to adsorption-based remediation methods. Carbon materials demonstrate exceptional efficiency, selectivity, and environmental compatibility in radionuclide adsorption. However, the practical application of conventional carbon materials is limited by their insufficient adsorption capacity and selectivity. Plasma modification has emerged as a highly effective strategy for enhancing the surface chemistry of carbon materials, thereby significantly improving their adsorption performance. This process increases the specific surface area of carbon materials and introduces a variety of functional groups, which in turn boost their capacity to adsorb radionuclides. This review systematically explores the progress made in modifying carbon-based adsorbents for the remediation of radioactive nuclides, with a particular emphasis on the mechanisms and effectiveness of plasma modification, covering studies on plasma-modified carbon materials for radionuclide adsorption published between 2009 and 2024. Furthermore, the review discusses the future prospects and practical applications of plasma-modified carbon materials in nuclear wastewater treatment, providing a scientific foundation for the development of efficient and sustainable remediation technologies. Full article

(This article belongs to the Special Issue Carbon Functionalization: From Synthesis to Applications)

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16 pages, 2472 KiB

Open AccessArticle

Green Synthesis of a Highly Active Ag/Activated Carbon Nanocomposite from Tamarind Seeds for Methyl Orange Removal

by Samah Daffalla, Nura Al Mousa, Hussain Ahmed, Jana Alsuwailem, Mustafa I. Almaghasla and Mohamed R. El-Aassar

C 2025, 11(2), 27; https://doi.org/10.3390/c11020027 - 17 Apr 2025

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Abstract

This study investigated the enhanced adsorption capacity of a silver nanoparticle (AgNPs)-incorporated tamarind seed activated carbon nanocomposite (Ag/TSAC) for the elimination of methyl orange (MO) from aqueous solutions. The nanocomposite was analyzed using TGA, SEM, FTIR, and BET, revealing a mesoporous structure with [...] Read more.

This study investigated the enhanced adsorption capacity of a silver nanoparticle (AgNPs)-incorporated tamarind seed activated carbon nanocomposite (Ag/TSAC) for the elimination of methyl orange (MO) from aqueous solutions. The nanocomposite was analyzed using TGA, SEM, FTIR, and BET, revealing a mesoporous structure with a surface area of 54.92 m²/g. The results showed that the structure of tamarind seeds altered during pyrolysis, as shown by the loss of many functional groups and a weight decrease of 66.61% in the nanocomposite. The efficiency of the nanocomposite in eliminating MO was assessed by batch adsorption studies, which also examined the effects of solution pH, starting MO concentration, and nanocomposite dose. The best MO removal was seen at pH 2, indicating a positive electrostatic interaction between the dye and adsorbent. The results demonstrated that the Ag/TSAC nanocomposite significantly enhanced MO removal efficiency from 19% to 96% under optimal adsorptive conditions, due to the synergistic effect of the high surface area of activated carbon and the enhanced adsorption sites provided by the AgNPs. The study demonstrates the potential of Ag/activated carbon nanocomposite as a sustainable adsorbent for removing MO dye from wastewater using a second-order model and Langmuir model. Full article

(This article belongs to the Special Issue Carbon Functionalization: From Synthesis to Applications)

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12 pages, 19666 KiB

Open AccessArticle

Modulation of Giant Magnetoimpedance Effect in Co-Based Amorphous Wires by Carbon-Based Nanocoatings

by Zhen Yang, Jiabao Huang, Jingyuan Chen and Chong Lei

C 2025, 11(2), 26; https://doi.org/10.3390/c11020026 - 1 Apr 2025

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Abstract

Co-based amorphous wires (Co-AWs) are functional materials renowned for their high impedance change rate in magnetic fields and a pronounced giant magnetoimpedance (GMI) effect. In this study, magnetron sputtering (MS) and dip-coating (DC) techniques were employed to fabricate carbon-based nanocoatings aimed at modulating [...] Read more.

Co-based amorphous wires (Co-AWs) are functional materials renowned for their high impedance change rate in magnetic fields and a pronounced giant magnetoimpedance (GMI) effect. In this study, magnetron sputtering (MS) and dip-coating (DC) techniques were employed to fabricate carbon-based nanocoatings aimed at modulating the GMI properties of Co-AWs. The magnetic properties and GMI responses of the composite Co-AWs with carbon-based coatings were comparatively analyzed. The results demonstrate that both methods effectively enhanced the GMI properties of the coated Co-AWs. The DC method emerged as a rapid and efficient approach for forming the coated film, achieving a modest enhancement in GMI performance (10% enhancement). In contrast, the MS technique proved more effective in improving the GMI effect, yielding superior results. Co-AWs coated via Ms exhibited smoother surfaces and reduced coercivity. Notably, the GMI effect increased with the thickness of the sputtered carbon coatings, reaching a maximum GMI effect of 522% (a remarkable 357% enhancement) and a sensitivity of 33.8%/Oe at a coating thickness of 334 nm. The observed trend in the GMI effect with carbon layer thickness corresponded closely to variations in transverse permeability, as determined by vibrating sample magnetometry (VSM). Furthermore, the carbon coating induced changes in the initial quenching stress on the surface of the Co-AWs, leading to alterations in impedance and a significant reduction in the characteristic frequency of the Co-AWs. Our findings provide valuable insights into the modulation of GMI properties in Co-AWs, paving the way for their optimized application in advanced magnetic sensor technologies. Full article

(This article belongs to the Section Carbon Materials and Carbon Allotropes)

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19 pages, 4792 KiB

Open AccessArticle

Conversion of Carbon Dioxide into Solar Fuels Using MgFe₂O₄ Thermochemical Redox Chemistry

by Rahul R. Bhosale

C 2025, 11(2), 25; https://doi.org/10.3390/c11020025 - 25 Mar 2025

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Abstract

Transforming H₂O and CO₂ into solar fuels like syngas is crucial for future sustainable transportation fuel production. Therefore, the MgFe₂O₄/CO₂ splitting cycle was thermodynamically scrutinized to estimate its solar-to-fuel energy conversion efficiency in this investigation. [...] Read more.

Transforming H₂O and CO₂ into solar fuels like syngas is crucial for future sustainable transportation fuel production. Therefore, the MgFe₂O₄/CO₂ splitting cycle was thermodynamically scrutinized to estimate its solar-to-fuel energy conversion efficiency in this investigation. The thermodynamic data required to solve the modeling equations were obtained using the HSC Chemistry program. The reduction non-stoichiometry was assumed to be equal to 0.1 for all computations. One of the study’s primary goals was to examine the impact of the inert sweep gas’s molar flow rate on the process parameters related to the MgFe₂O₄/CDS cycle. Overall, it was understood that the effect of the inert sweep gas’s molar flow rate on the thermal reduction temperature was significant when it increased from 10 to 40 mol/s compared to the rise from 40 to 100 mol/s. The energy needed to reduce MgFe₂O₄ increased slightly due to the surge in the inert sweep gas’s molar flow rate. In contrast, the energy penalty for heating MgFe₂O_4-δred from the re-oxidation to thermal reduction temperature significantly decreased. Including gas-to-gas heat exchangers with a gas-to-gas heat recovery effectiveness equal to 0.5 helped reduce the energy demand for heating the inert sweep gas. Overall, although the rise in the inert sweep gas’s molar flow rate from 10 to 100 mol/s caused a drop in the thermal reduction temperature by 180 K, the total solar energy needed to drive the cycle was increased by 85.7 kW. Accordingly, the maximum solar-to-fuel energy conversion efficiency (13.1%) was recorded at an inert sweep gas molar flow rate of 10 mol/s, which decreased by 3.7% when it was increased to 100 mol/s. Full article

(This article belongs to the Section CO₂ Utilization and Conversion)

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