Physchem

This review explores CO₂ methanation and steam methane reforming (SMR) as two key thermochemical processes governed by reversible reactions, each offering distinct contributions to carbon-neutral energy systems. The objective is to provide a comparative assessment of both processes, highlighting how reaction reversibility can be strategically leveraged for decarbonization. The study addresses methane production via CO₂ methanation and hydrogen production via SMR, focusing on their thermodynamic behaviors, catalytic systems, environmental impacts, and economic viability. CO₂ methanation, when powered by renewable hydrogen, can result in emissions ranging from −471 to 1076 kg CO₂-equivalent per MWh of methane produced, while hydrogen produced from SMR ranges from 90.9 to 750.75 kg CO₂-equivalent per MWh. Despite SMR’s lower production costs (USD 21–69/MWh), its environmental footprint is considerably higher. In contrast, methanation offers environmental benefits but remains economically uncompetitive (EUR 93.53–204.62/MWh). Both processes rely primarily on Ni-based catalysts, though recent developments in Ru-based and bimetallic systems have demonstrated improved performance. The review also examines operational challenges such as carbon deposition and catalyst deactivation. By framing these technologies through the shared lens of reversibility, this work outlines pathways toward integrated, efficient, and circular energy systems aligned with long-term sustainability and climate neutrality goals. Full article

Plastic waste and water pollution demand circular economy-driven innovations. This review examines metal–organic framework (MOF) synthesis from polyethylene terephthalate (PET) waste for wastewater treatment. Depolymerized PET yields terephthalic acid and ethylene glycol—essential MOF precursors. We evaluate the following: (1) PET depolymerization (hydrolysis, glycolysis, ammonolysis) for monomer recovery efficiency; (2) MOF synthesis (solvothermal, microwave, mechanochemical) using PET-derived linkers; (3) performance in adsorbing heavy metals, dyes, and emerging contaminants. PET-based MOFs match or exceed commercial adsorbents in pollutant removal while lowering costs. Their tunable porosity and surface chemistry enhance selectivity and capacity. By converting waste plastics into functional materials, this strategy tackles dual challenges: diverting PET from landfills and purifying water. The review underscores the environmental and economic benefits of waste-sourced MOFs, proposing scalable routes for sustainable water remediation aligned with zero-waste goals. Full article

Conductive polymer composites (CPCs) filled with anisotropic materials such as carbon nanotubes (CNTs) exhibit electrical behavior governed by percolation through filler networks. While filler volume and shape are commonly studied, the influence of orientation and alignment remains underexplored. This study uses Monte Carlo simulations to examine how the mean orientation angle and angular dispersion of CNTs affect conductive network formation. The results demonstrate that electrical connectivity is highly sensitive to orientation. Contrary to conventional assumptions, maximum connectivity occurred not at 45° but at around 55–60°. A Gaussian-based orientation probability function was proposed to model this behavior. Additionally, increased orientation dispersion enhanced conductivity in cases where alignment initially hindered connection, highlighting the dual role of alignment and randomness. These findings position orientation as a critical design parameter—beyond filler content or geometry—for engineering CPCs with optimized electrical performance. The framework provides guidance for processing strategies that control alignment and supports applications such as stretchable electronics, directional sensors, and multifunctional materials. Future research will incorporate full 3D orientation modeling to reflect complex manufacturing conditions. Full article

The research reviews and contrasts two studies based on the gas-phase reaction OH + D₂(v, j). In these studies, Quasi-Classical Trajectory (QCT) calculations and the Gaussian Binning (GB) technique were used on the Wu–Schatz–Lendvay–Fang–Harding (WSLFH) potential energy surface. Large sample sizes allow for precise energy state distribution analysis across translational, vibrational, and rotational components in the products. A key observation is the influence of the vibrational and rotational excitation of D₂ on the total angular momentum (J′) of the HOD* product. This study reveals that increasing the vibrational level, vD₂, significantly shifts P(J′) distributions toward higher values, broadening them due to increased isotropy. In contrast, increasing the rotational level, jD₂, results in a smaller shift but introduces greater anisotropy, leading to a more selective distribution of J′ values. The dual Gaussian Binning selection—Vibrational-GB followed by Rotational-GB—further highlights a preference for either odd or even J′ values, depending on the specific excitation conditions. These findings have implications for the development of chemical lasers, as the excitation and emission properties of HOD* can be leveraged in the laser design. Future research aims to extend this study to a broader range of initial conditions, refining the understanding of reaction dynamics in controlled gas-phase environments. Full article

Solid oxide fuel cells (SOFCs) represent a pivotal technology in renewable energy due to their clean and efficient power generation capabilities. Their role in potential carbon mitigation enhances their viability. SOFCs can operate via a variety of alternative fuels, including hydrocarbons, alcohols, solid carbon, and ammonia. However, several solutions have been proposed to overcome various technical issues and to allow for stable operation in dry methane, without coking in the anode layer. To avoid coke formation thermodynamically, methane is typically reformed, contributing to an increased degradation rate through the addition of oxygen-containing gases into the fuel gas to increase the O/C ratio. The performance achieved by reforming catalytic materials, comprising active sites, supports, and electrochemical testing, significantly influences catalyst performance, showing relatively high open-circuit voltages and coking-resistance of the CH₄ reforming catalysts. In the next step, the operating principles and thermodynamics of methane reforming are explored, including their traditional catalyst materials and their accompanying challenges. This work explores the components and functions of SOFCs, particularly focusing on anode materials such as perovskites, Ruddlesden–Popper oxides, and spinels, along with their structure–property relationships, including their ionic and electronic conductivity, thermal expansion coefficients, and acidity/basicity. Mechanistic and kinetic studies of common reforming processes, including steam reforming, partial oxidation, CO₂ reforming, and the mixed steam and dry reforming of methane, are analyzed. Furthermore, this review examines catalyst deactivation mechanisms, specifically carbon and metal sulfide formation, and the performance of methane reforming and partial oxidation catalysts in SOFCs. Single-cell performance, including that of various perovskite and related oxides, activity/stability enhancement by infiltration, and the simulation and modeling of electrochemical performance, is discussed. This review also addresses research challenges in regards to methane reforming and partial oxidation within SOFCs, such as gas composition changes and large thermal gradients in stack systems. Finally, this review investigates the modeling of catalytic and non-catalytic processes using different dimension and segment simulations of steam methane reforming, presenting new engineering designs, material developments, and the latest knowledge to guide the development of and the driving force behind an oxygen concentration gradient through the external circuit to the cathode. Full article

Food irradiation is gaining popularity worldwide due to its potential to extend shelf life, improve hygienic quality, and meet trade requirements. The electron paramagnetic resonance (EPR) method is a reliable and sensitive technique for detecting untreated and irradiated foods. This study investigated the effectiveness of EPR in identifying irradiated meat and seafood containing bones. Beef, lamb, chicken, and various fish were irradiated with electron beams at different doses and analysed using an EPR spectrometer. During irradiation, the food samples were surrounded by small ice bags to prevent autodegradation of cells and nuclei. After the irradiation process, the samples were stored at −20 °C. For EPR signal recording, the flesh, connective tissues, and bone marrow were removed from the bone samples, which were then oven-dried at 50 °C. The EPR spectra were recorded using an X-band EPR analyzer. Unirradiated and irradiated samples were identified based on the nature of the EPR signals as well as the g-values of symmetric and asymmetric signals. The study found that the EPR method is effective in distinguishing between unirradiated and irradiated bone-containing foods across nearly all applied radiation doses. The peak-to-peak amplitude of the EPR signals increased with increasing radiation doses. It was observed that unirradiated bone samples showed low-intensity symmetrical signals, while irradiated samples showed typical asymmetric signals. Overall, the study demonstrated that the EPR method is a reliable and sensitive technique for identifying irradiated foods containing bones and can be used for the control, regulation, and proper surveillance of food irradiation. Full article

In power transformers, insulating liquids are essential for cooling, insulation, and condition monitoring. However, the environmental impact and biodegradability issues of traditional hydrocarbon-based liquids have spurred interest in green alternatives like natural esters. Despite their benefits, natural esters are highly prone to oxidation, limiting their broader use. This study explores a novel blend of two plant-based oils, canola oil and methyl ester derived from palm kernel oil, enhanced with two antioxidants, Tert-butylhydroquinone (TBHQ) and 2,6-Di-tert-butyl-4-methyl-phenol (BHT), to improve oxidation resistance. The performance of this antioxidant-infused oil was evaluated in terms of its interaction with Kraft paper insulation through accelerated thermal aging over periods of 10, 20, 30, and 40 days. Key properties, including the viscosity, breakdown voltage, conductivity, and FTIR spectra of oils, were analyzed before and after aging. Additionally, the degradation of the Kraft paper was investigated using scanning electron microscopy (SEM), optical microscopy, and dielectric strength tests. The results show that the antioxidant-treated oil exhibits significantly enhanced molecular stability, reduced viscosity, lower conductivity, and improved breakdown voltage (53.16 kV after 40 days). Notably, the oil mixture maintained the integrity of the Kraft paper insulation better than traditional natural esters, demonstrating superior dielectric properties and a promising potential for more sustainable and reliable power transformer applications. Full article

A comprehensive investigation of the chemical bonding, electronic structure, and spectroscopic properties of the lanarkite-type Pb₂SO₅ (PSO) structure was conducted, for the first time, using density functional theory simulations. Thus, different functionals, PBE, PBE0, PBESOL, PBESOL0, BLYP, WC1LYP, and B3LYP, were used, and their results were compared to predict their fundamental properties accurately. All DFT calculations were performed using a triple-zeta valence plus polarization basis set. Among all the DFT functionals, PBE0 showed the best agreement with the experimental and theoretical data available in the literature. Our results also reveal that the [PbO₅] clusters were formed with five Pb–O bond lengths, with values of 2.29, 2.35, 2.57, 2.60, and 2.79 Å. Meanwhile, the [SO₄] clusters exhibited uniform S–O bond lengths of 1.54 Å. Also, a complete topological analysis based on Bader’s Quantum Theory of Atoms in Molecules (QTAIM) was applied to identify atom–atom interactions in the covalent and non-covalent interactions of the PSO structure. Additionally, PSO has an indirect band gap energy of 4.83 eV and an effective mass ratio ($m_h^{*}$/$m_e^{*}$) of about 0.192 (PBE0) which may, in principle, indicate a low degree of recombination of electron–hole pairs in the lanarkite structure. This study represents the first comprehensive DFT investigation of Pb₂SO₅ reported in the literature, providing fundamental insights into its electronic and structural properties. Full article

The recovery of green waste and biomass presents a significant challenge in the 21st century. In this context, this study aims to valorize waste generated by the fruit juice processing industry at the N’Gaous unit (composed of the orange peel, fibers, pulp, and seeds) as an adsorbent to eliminate an anionic dye and to enhance its adsorption capacity through thermal activation at 200 °C and 400 °C. The aim is also to determine the parameters for the adsorption process including contact time (0–120 min), solution pH (2–10), initial dye concentration (50–700 mg/L), and adsorbent dosage (0.5–10 g/L). The adsorption tests showed that waste activated at 400 °C (AR400) demonstrated a higher efficiency for removing indigo carmine (IC) from an aqueous solution than waste activated at 200 °C (AR200) and unactivated waste (R). The experimental maximum adsorption capacities for IC were 70 mg/g for unactivated waste, 500 mg/g for waste activated at 200 °C, and 680 mg/g for waste activated at 400 °C. These tests were conducted under conditions of pH 2, an equilibrium time of 50 min, and an adsorbent concentration of 1 g/L. The analysis of the kinetic data revealed that the pseudo-second-order model provides the best fit for the experimental results, indicating that this mechanism predominates in the sorption of the pollutant onto the three adsorbents. In terms of adsorption isotherms, the Freundlich model was found to be the most appropriate for describing the adsorption of dye molecules on the R, AR200, and AR400 supports, owing to its high correlation coefficient. Before adsorption tests, the powder R, AR200 and AR400 were characterized by various analyses, including Fourier transform infrared (FTIR), pH zero charge points and laser granularity for structural evaluation. According to the results of these analyses, the specific surface area (SSA) of the prepared material increases with the increase in the activation temperature, which expresses the increase in the adsorption of material activated at 400 °C, compared with materials activated at 200 °C and the raw material. Full article

A 3-Amino-Propyl Trimethoxy Silane (APTS) functionalized silica was prepared and investigated. The functionalized silica showed a powerful removal behavior towards Chromium (III) [Cr (III)] and Cadmium (II) [Cd (II)] ions in aqueous solution. Different factors affecting the heavy metal ions adsorption on these substrates such as pH, initial concentration, contact time, and temperature were investigated. FT-IR analyses were carried out to characterize the functionalization of salicylaldehyde unto 3-aminopropyl silica. Results showed that optimum adsorption of the metal ions occurred at a pH of 7 and 6 by the pure silica and functionalized silica, respectively. Removal efficiencies of the adsorbents showed the trend: Salicylaldehyde-APTS modified > pure silica. The adsorption was described by the Langmuir adsorption isotherm. The kinetic results showed that the adsorption was described well with the pseudo second-order kinetic model. The study reveals that both pure silica and functionalized silica can be used as good adsorbents for the removal of the heavy metal pollutants from aqueous solutions and may be applied in the treatment of industrial waste waters, and they may be useful in detoxifying our already polluted environments. Full article

The aim of the study was to investigate the fixation of Cr(VI) ions from contaminated sediments using synthetic zeolite 4A and natural zeolite clinoptilolite. Parameters such as pH, contact time, adsorption mass and temperature were investigated. If the ions of the heavy metals were mobile, they would become toxic to the environment. After sediment digestion, the initial and final concentrations of Cr(VI) were measured in sediment samples with or without zeolite. Inductively coupled plasma with optical emission spectroscopy (ICP-OES) and X-ray diffraction (XRD) were used to characterize the material. The adsorption kinetics were investigated using a pseudo-first order model, a pseudo-second order model, and an intra-particle diffusion model. The results showed that the zeolites enhanced the fixation of Cr(VI). Chemisorption was the main mechanism when using acid-modified zeolite. Full article

Aluminium is an attractive material for proton-exchange-membrane fuel cell bipolar plates as it has a much lower density than steel and is easier to form than both steel and graphite. This work focused on the development of amorphous carbon films deposited using closed-field unbalanced magnetron sputtering (CFUBMS) in order to improve the corrosion resistance of aluminium bipolar plates and to enhance fuel cell performance and durability. Chromium and tungsten adhesion layers were used for the coatings. It was possible to achieve good electrical conductivity and high electrochemical corrosion resistance up to 70 °C on polished Aluminium alloy 6082 by tuning the deposition parameters. Coatings with a tungsten adhesion layer showed better corrosion resistance than those with a chromium adhesion layer. In situ, accelerated stress testing of single cells was performed using uncoated and coated Al6082 bipolar plates. Both coatings resulted in improved fuel cell performance compared to uncoated aluminium when used on the cathode side of the fuel cell. Full article

This work successfully synthesized green zinc oxide nanoparticles using extracts from strawberry guava leaves (Psidium cattleianum Sabine). Additionally, the reducing effect of the antioxidant extracts obtained through traditional techniques, such as infusion and maceration, was studied and compared against an emerging unconventional technology like ultrasound assisted extraction. Regarding the physical and chemical characteristics, it was found that all three systems were confined within a wavelength range of 357 to 370 nm (UV-vis) and sizes from 60 to 140 nm for the ultrasound-assisted nanoparticles (SEM), corroborated with DLS (134 ± 60 nm). Through X-ray diffraction, the hexagonal wurtzite structure was elucidated, and it was observed that ultrasound favored a higher percentage of crystallinity (98%) compared to the infusion (84%) and maceration (72%). This could be correlated with different functional groups via FTIR and with thermal events associated with thermogravimetric curves, where the total biomass weight loss was lower for nanoparticles using ultrasound extract (6.25%), followed by maceration (15.55%) and infusion (18.01%) extracts. Furthermore, these nanostructures were evaluated against clinically relevant pathogens, including Salmonella enteritidis, Staphylococcus aureus, Escherichia coli O157:H7, and Pseudomonas aeruginosa, assessing bacterial growth inhibition using the microdilution technique, and achieving inhibitions of 75%. Biofilm activity was evaluated through Congo red and crystal violet assays, where ultrasound-derived NPs proved to be good inhibitors for all pathogens. Finally, the toxicity of the nanoparticles was analyzed against peripheral blood leukocytes from goats as well as on the 3 T3-L1 cell line used in anti-obesity assays; the nanoparticles proved to be suitable in all concentrations reaching around 100% cell viability, positioning them as good candidates for diverse industrial applications that align with the principles of green chemistry towards a circular economy. Full article

Troponin C (TnC) is the Ca²⁺-sensing subunit of troponin that is responsible for activating thin filaments in striated muscle, and, in turn, for regulating the systolic and diastolic contractile function of cardiac muscle. The secondary structure of vertebrate TnC is mainly composed of α-helices, with nine helices named sequentially, starting from the amino terminus, from N to A–H. The N-helix is a 12-residue-long α-helix located at the extreme amino terminus of the protein and is the only helical structure that does not participate in forming Ca²⁺-binding EF-hands. Evolutionarily, the N-helix is found only in TnC from mammalian species and most other vertebrates and is not present in other Ca²⁺-binding protein members of the calmodulin (CaM) family. Furthermore, the primary sequence of the N-helix differs between the genetic isoforms of the fast skeletal TnC (sTnC) and cardiac/slow skeletal TnC (cTnC). The 3D location of the N-helix within the troponin complex is also distinct between skeletal and cardiac troponin. Physical chemistry and biophysical studies centered on the sTnC N-helix demonstrate that it is crucial to the thermal stability and Ca²⁺ sensitivity of thin filament-regulated MgATPase activity in solution and to isometric force generation in the sarcomere. Comparable studies on the cTnC N-helix have not yet been performed despite the identification of cardiomyopathy-associated genetic variants that affect the residues of cTnC’s N-helix. Here, we review the current status of the research on TnC’s N-helix and establish future directions to elucidate its functional significance. Full article

Bio-hybrid fuels, chemically derived from sustainable raw materials and green energies, offer significant potential to reduce carbon dioxide emissions in the transport sector. However, when these fuels are used as drop-in replacements in internal combustion engines, material compatibility with common sealing materials is not always given. Within the cluster of excellence, “The Fuel Science Center (FSC)” at RWTH Aachen, experimental immersion tests were conducted on a limited set of fuel and sealing material combinations. Given the extensive range of possible fuel and sealing combinations, a data-based machine learning prediction framework was developed and validated to pre-select promising fuel candidates. Due to the limited number of samples, preliminary results indicate a need to expand the database. Since experimental investigations are time-consuming and costly, this work explores faster physics-motivated data generation approaches by modeling molecular interactions between fuel and sealing materials. Two modeling scales are employed. One calculates the intermolecular distance using density functional theory. The other uses Hansen solubility parameters, representing an abstract modeling of intermolecular forces. Both approaches are compared, and their limitations are assessed. Including the generated data in the prediction framework improves its accuracy. Full article

This review focuses on the rheological behavior of polystyrene (PS) composites reinforced with carbon nanotubes (CNTs), providing an in-depth analysis of how CNT incorporation affects the viscosity, elasticity, and flow properties of these materials. The review covers fundamental aspects of PS and CNT structures, emphasizing their influence on the composite’s rheological properties. Key interaction mechanisms, including van der Waals forces and covalent bonding, are discussed for their role in determining material behavior. Various preparation methods, such as melt mixing, solution mixing, and in situ polymerization, are evaluated based on their impact on CNT dispersion and rheological performance. The study examines critical rheological parameters such as relative and complex viscosity, shear thinning, and elasticity, supported by theoretical models and experimental findings. The review also identifies major challenges, such as achieving uniform CNT dispersion and addressing processing limitations, while offering insights into future research directions aimed at improving the rheological performance and scalability of PS/CNT composites for advanced applications. Full article

The removal of cadmium ions (Cd²⁺) using raw argan shells (ArS) was optimized through experimental and theoretical studies. Adsorption experiments revealed optimal conditions at an adsorbent dose of 3.5 g, an initial Cd²⁺ concentration of 20 mg·L⁻¹, and a pH of 8, achieving a maximum sorption capacity of 3.92 mg·g⁻¹. The kinetic analysis showed that the adsorption followed a pseudo-second-order model (R² = 0.98), and the Langmuir isotherm model predicted a maximum adsorption capacity of 4 mg·g⁻¹. Thermodynamic analysis indicated an endothermic adsorption process, with ΔG° shifting from positive to negative as temperature increased, confirming that adsorption is favored at higher temperatures. Desorption studies demonstrated that HCl was the most effective eluting agent, achieving a desorption efficiency of 90.02%, followed by HNO₃ (76.65%) and CH₃COOH (71.59%). The varying desorption efficiencies were attributed to differences in acid strength and ionic interactions with Cd²⁺. This study demonstrates the potential of raw argan shells as an efficient, reusable, and sustainable biosorbent for cadmium removal, offering a promising solution for water treatment and environmental remediation. Full article

In this research, the use of machine learning techniques for predicting the state of health (SoH) of 5 Ah—21,700 lithium-ion cells were explored; data from an experimental aging test were used to build the prediction model. The main objective of this work is to develop a robust model for battery health estimation, which is crucial for enhancing the lifespan and performance of lithium-ion batteries in different applications, such as electric vehicles and energy storage systems. Two machine learning models: support vector regression (SVR) and random forest (RF) were designed and evaluated. The random forest model, which is a novel strategy for SoH prediction application, was trained using experimental features, including current (A), potential (V), and temperature (°C), and tuned through a grid search for performance optimization. The developed models were evaluated using two performance metrics, including R² and root mean squared error (RMSE). The obtained results show that the random forest model outperformed the SVR model, achieving an R² of 0.92 and an RMSE of 0.06, compared to an R² of 0.85 and an RMSE of 0.08 for SVR. These findings demonstrate that random forest is an effective and robust strategy for SoH prediction, offering a promising alternative to existing SoH monitoring strategies. Full article

Nanomaterials have attracted significant attention in recent decades for their diverse applications, including energy storage devices like supercapacitors. Among these, cobalt oxide (Co₃O₄) nanostructures stand out due to their high theoretical capacitance, unique electrical properties, and tunable morphology. This study explores the hydrothermal synthesis of Co₃O₄, revealing that the molar ratio of cobalt nitrate to potassium hydroxide significantly influences the morphology, crystal structure, and electrochemical performance. An optimized 1:1 molar ratio (COK 11) yielded well-defined cubic nanostructures with uniform elemental distribution, as confirmed by SEM, TEM, and EDS analyses. Structural characterization through XRD, XPS, and FTIR validated the formation of the Co₃O₄ spinel phase with distinctive lattice and surface oxygen features. Electrochemical property analysis demonstrated the superior performance of the COK 11 electrode, achieving a high specific capacity of 825 ± 3 F/g at a current density of 1 A/g, a rate capability of 56.88%, and excellent cycle stability of 88% at 3 A/g after 10,000 cycles. These properties are attributed to the nano-cubic morphology and interconnected porosity, which enhanced ion transport and active surface area. This study highlights the importance of synthesis parameters in tailoring nanomaterials for energy storage, establishing COK 11 as a promising candidate for next-generation high-performance supercapacitor applications. Full article