Gibbs Free Energy Research Articles

Kinetic and thermodynamic study of maize stalk biomass using thermogravimetric analysis

Abstract Investigating thermodynamic and kinetic aspects is crucial for assessing efficiency of converting biomass into energy. This study presents kinetic and thermodynamic characteristics of maize stalk using thermogravimetric analysis. The novelty of this research stems from the combination of kinetic and thermodynamic analysis, the application of multiple kinetic models and understanding of pyrolysis-based bioenergy production process from maize stalk. Analysis was performed using a temperature range of 25–650 °C employing 5, 10, 15 and 20 °C/min heating rate. The temperature range of 250–650 °C was selected to analyze the complete decomposition of the three main components of maize stalk i.e. hemicellulose, cellulose and lignin and to prevent the decomposition of inorganic substances such as CaCO3 which decompose at high temperature. The apparent activation energy values were evaluated using Kissinger-Akahira-Sunose (KAS), Friedman and Ozawa-Flynn-Wall (OFW) models. The resulting mean apparent Ea values calculated for KAS, Friedman and OFW were 167.86, 177.34 and 162.96 kJ/mol, accordingly. Additionally, Gibbs free energy (ΔG) values were 164.17 kJ/mol, enthalpy (ΔH) −178.31 J/molK and entropy (ΔS) 285.59 kJ/mol, respectively. These findings suggest that maize stalk holds promise as a potential bioenergy source, aligning with sustainable goals and waste-to-energy strategies.

Reaction Pathway Regulation for Gaseous and Liquid Products of Electrocatalytic CO2 Reduction under Adsorbate Interactions

Halide anion adsorption on transition metals can improve the performance of electrochemical CO2 reduction reaction (CO2RR), while the specific reaction mechanisms governing selective CO2RR pathways remain unclear. In this study, we demonstrate for the first time the distinct pathways for gaseous (CO) and liquid products (formate and ethanol) on the well‐defined Ag‐Cu nanostructures with controlled chlorination, respectively. We show that CO2 conversion to CO on Ag/AgCl can be tuned by adjusting the thickness of AgCl layer, achieving a Faradaic efficiency (FE) near 100% over a broad potential range in a 0.5 M KHCO3 using flow cell. In contrast, the optimized Cl‐Ag/Cu system enables the conversion of CO2 into liquid products including formate and ethanol with a total FE nearing 100%, delivering high current density under similar conditions. In situ infrared experiments and theoretical calculations reveal that the lateral adsorbate of *OCHO intermediate facilitates the thermodynamics of both the CO pathway on Cl‐Ag(111) and the formate pathway on Cl‐Ag/Cu(111) by reducing Gibbs free energy barriers of each potential‐limit step. This work uncovers the role of chlorination in the tuning of C‐bound or O‐bound intermediates during CO2RR on Ag‐Cu catalysts, determining the reaction pathway under lateral adsorbate effects.

Reaction Pathway Regulation for Gaseous and Liquid Products of Electrocatalytic CO2 Reduction under Adsorbate Interactions.

Halide anion adsorption on transition metals can improve the performance of electrochemical CO2 reduction reaction (CO2RR), while the specific reaction mechanisms governing selective CO2RR pathways remain unclear. In this study, we demonstrate for the first time the distinct pathways for gaseous (CO) and liquid products (formate and ethanol) on the well-defined Ag-Cu nanostructures with controlled chlorination, respectively. We show that CO2 conversion to CO on Ag/AgCl can be tuned by adjusting the thickness of AgCl layer, achieving a Faradaic efficiency (FE) near 100% over a broad potential range in a 0.5 M KHCO3 using flow cell. In contrast, the optimized Cl-Ag/Cu system enables the conversion of CO2 into liquid products including formate and ethanol with a total FE nearing 100%, delivering high current density under similar conditions. In situ infrared experiments and theoretical calculations reveal that the lateral adsorbate of *OCHO intermediate facilitates the thermodynamics of both the CO pathway on Cl-Ag(111) and the formate pathway on Cl-Ag/Cu(111) by reducing Gibbs free energy barriers of each potential-limit step. This work uncovers the role of chlorination in the tuning of C-bound or O-bound intermediates during CO2RR on Ag-Cu catalysts, determining the reaction pathway under lateral adsorbate effects.

A comparative application of spectrophotometric and spectrofluorimetric methods to estimate levofloxacin-DNA and ofloxacin-DNA interactions.

Ofloxacin (OFL) and its (S)-enantiomer, levofloxacin (LEV), are among members of the fluoroquinolone antibiotic class, renowned for their broad-spectrum efficacy against both gram-negative and gram-positive bacteria. These potent drugs have been widely used in both human and veterinary medicine, working as bactericidal agents by binding to DNA gyrase, an essential enzyme for bacterial DNA replication. Understanding the binding constants of these drugs to DNA is vital for elucidating their interaction mechanisms and enhancing our grasp of gene expression regulation. The interactions of LEV and OFL with calf thymus DNA under a physiological medium (0.02M tris-HCl buffer, pH 7.4) using UV spectrophotometry and spectrofluorimetry were investigated. The assay results obtained by applying two spectroscopic approaches confirmed the presence of the interaction of LEV and OFL antibiotics with DNA. In the LEV-DNA and OFL-DNA interactions, hyperchromic effect and fluorescence quenching were observed for UV spectrophotometric and spectrofluorometric measurements, respectively. In the spectrophotometric analysis, the binding constants for the LEV-DNA and OFL-DNA complexes at 298K were determined as (1.24 ± 0.047) x 103 and (1.39 ± 0.040) x 103 M- 1, respectively. In the spectrofluorimetric analysis of the interaction of LEV and OFL with DNA, the thermodynamic properties were examined at three distinct temperatures. Based on the fluorescence signal changes the binding constants at 293, 298, and 310K were calculated as (8.91 ± 0.161) x 103, (7.62 ± 0.098) x 103, and (6.08 ± 0.041) x 103 M- 1 for LEV-DNA and, (3.14 ± 0.053) x 103, (3.04 ± 0.031) x 103, and (2.78 ± 0.023) x 103 M- 1 for OFL-DNA, respectively. In these assays, the Gibbs free energy (ΔG0), entropy (ΔS0), and enthalpy (ΔH0) were determined using the Van't Hoff equation. The negative ΔG⁰ values indicate that both LEV-DNA and OFL-DNA interactions are spontaneous. Furthermore, the positive ΔS⁰ and negative ΔH⁰ values revealed that electrostatic forces played a significant role in the binding LEV and OFL to DNA.

Adsorptive removal of 2,4-dichlorophenol from aqueous solution using micronized oil shale

This study investigated the utilization of a unique oil shale as a sorbent for the removal of 2,4-dichlorophenol (2,4-DCP) from aqueous solutions. The influence of various process parameters, including the contact time, sorbent/liquid ratio, pH, and temperature, on the sorption process was evaluated. The results indicated the near-complete sorption of 2,4-DCP within 24 h. Favorable sorption was observed either at a sorbent/liquid ratio of 1:10, at elevated temperatures (40 °C), or at lower pH values (pH = 5) within the examined range. The maximum adsorption capacity at 40 °C has the potential to reach up to 20.0 µmol/g. Langmuir, Freundlich, and Sips isotherms were applied to the experimental data, but the Sips isotherm provided a superior fit, suggesting a heterogeneous sorption. Kinetic studies revealed a two-stage process: intraparticle diffusion dominated the initial stage, whereas other rate-limiting mechanisms may have contributed to the second stage. The first- and second-order kinetic models suggested a combined mechanism. According to the thermodynaic study, the adsorption process was spontaneous and exothermic, as indicated by the negative Gibbs free energy change and enthalpy change, which suggest that physisorption predominated. These findings demonstrate the potential of the investigated oil shale as an unconventional and cost-effective sorbent, potentially serving as a substitute for activated carbon in 2,4-DCP removal.Graphical abstract

Exploring the Intrinsic Effects of Lattice Strain on the Hydrogen Evolution Reaction via Electric-Field-Induced Strain in FePt Films.

Strain engineering has the potential to modify the adsorption process and enhance the electrocatalytic activity, especially in the hydrogen evolution reaction (HER). However, the introduction of lattice strain in electrocatalysts is often accompanied by a change in chemical composition, surface morphology, or phase structure to a certain extent, impeding the investigation of the intrinsic strain effect on HER. In this work, the FePt film was deposited on a Pb(Mg1/3Nb2/3)0.7Ti0.3O3 (PMN-PT) substrate to construct the FePt/PMN-PT heterojunction, and the continuously adjustable nonvolatile lattice strain is induced by the asymmetric electric field manipulation avoiding the aforementioned disturbance factors. HER experimental results demonstrate a drastic improvement in the overpotential of FePt with the largest tensile strain of 3000 ppm, and the observed variation of HER performance indicates an upward trend as the tensile strain increases. Density functional theory calculations reveal that the Gibbs free energy of FePt with the appropriate tensile strain is closer to zero, attributed to the downward shift of the d-band center. Our study provides an approach to continuously regulate the lattice strain with less interference factors, facilitating the exploration of the intrinsic strain effect on a wide range of catalysts.

Synthesis, characterization, biodegradation, and evaluation of the surface‐active properties of non‐ionic gemini surfactants derived from lauryl diethanolamide

AbstractThe surface activities and application properties of aqueous solution surfactants are greatly influenced by their structure, especially the spacer group that connects the polar head groups. Herein, four new non‐ionic Gemini surfactants with different spacers were designed and synthesized, and their surfactant properties and biodegradability were studied. The synthesis of these compounds involves a two‐step procedure. The first step is the formation of an amide from lauric acid and diethanolamine. The second step is the reaction of lauryl diethanolamide with four different spacers, the latter being flexible‐hydrophilic, and rigid‐hydrophobic in structure, respectively. Their structures were characterized using 1H NMR, 13C NMR, FT‐IR, and ESI‐MS. The critical micelle concentration (CMC), the surface tension at CMC (γCMC), the efficiency of these compounds to reduce the surface tension by 20 mN/m (C20 and pC20), the effectiveness (πCMC), the maximum surface excess (Γmax), and the minimum surface area (Amin) were measured at 20, 40, and 50°C. The molecular architecture of the spacers in these compounds strongly influences the thermodynamic parameters, such as the standard change for Gibbs free energy of adsorption (ΔG°ads) and the standard change for Gibbs free energy of micellization (ΔG°mic). The ability of these surfactants to reduce surface tension is particularly good, but their distinguishing characteristic is their high relative propensity to form micellar aggregates. This aggregation ability improves as the hydrophilicity and flexibility of the spacer increase. Finally, in less than 30 days, all non‐ionic Gemini surfactants were determined to be 99% biodegradable in river water.

Insights into the anomalous hardness of the tantalum carbides from dislocation mobility

The tantalum carbides, TaCx, have been repeatedly shown to harden dramatically with some loss of carbon content, then soften with further decarburization. First observed in 1963, this anomalous hardness behavior has been reproduced for decades without satisfactory explanation. Prior attempts to characterize this phenomenon using elastic stiffnesses have failed to reproduce the anomalous hardness behavior. In this work, we demonstrate a change in slip system preference from {111}B1 to {110}B1 in TaCx as x decreases, while no such transition is observed in TiCx. We find this to be the primary mechanism of the anomalous hardness, arising from reduced energetic favorability of dissociation of dislocations on {111}B1 into Shockley partials at lower carbon contents. We also present experimental hardness measurements for bulk and thin-film TaCx at different carbon contents. An anomalous hardness peak is observed in the bulk samples, but not in the thin films, due to loss of dislocation plasticity in the nanocrystalline films.

Fundamental Thermodynamic Aspects for the Effective Dispersion of Carbon Nanotubes and Improve Performance Grade of Bitumen

The application of carbon nanotubes to enhance bitumen properties is relevant due to the need to increase the durability of asphalt concrete pavements and reduce maintenance costs. Key areas requiring further study include the processes during ultrasonic dispersion, the selection of the optimal medium, and the stability of the resulting dispersions. This study examines dispersions containing multi-walled carbon nanotubes (MWCNTs) Taunit M (from 5·10−4 to 5·10−2%) and various hydrocarbon plasticizers. For the first time, the change in Gibbs free energy, enthalpy (interaction energy), and mixing and disordering entropy was calculated based on experimental data (surface tension, average cubic diameter of MWCNTs, molecular mass, etc.). The data were compared with the storage stability of polymer-modified binders (PMBs). It was found that mixing entropy plays a key role in forming thermodynamically stable dispersions, while the contribution of disordering entropy is minimal. High dispersion enthalpy of MWCNTs can reduce dispersion stability at high concentrations despite entropy growth. Systems with selective purification extracts showed the best PMB stability despite thermodynamic instability. The property changes after 3 days at 180 °C were no more than 5%. This suggests structural changes from component interactions are critical, highlighting the need for an integrated approach considering both thermodynamic and macroscopic properties.

Natural Flavonoids as Primary Amoebic Meningoencephalitis Inhibitor: Virtual Screening, Molecular Docking, MD Simulation, MMPBSA, Density Functional Theory, Principal Component, and Gibbs Free Energy Landscape Analyses

ABSTRACTFlavonoids have been showing diversified bioactivities. Primary amoebic meningoencephalitis is a brain inflammation caused by Naegleria fowleri brain eating amoeba. In this manuscript, we selected 93 flavonoids by extensive literature survey and 83 flavonoids passed drug likeness parameter. Selected flavonoids were molecular docked against primary amoebic meningoencephalitis N. fowleri CYP51 receptor considering voriconazole as standard. Beta naphthoflavone, abyssinone I, and abyssinone III showed maximum docking scores of −10.9 kcal/mol, −10.7 kcal/mol, and −10.6 kcal/mol, respectively, whereas voriconazole showed docking scores of −7.6 kcal/mol. Molecular dynamic simulation data showed that RMSD values attained almost a static value during the simulation, and all nearest interacting amino acid residues were fluctuated within limit. Molecular Mechanics Poisson‐Boltzmann Surface Area (MMPBSA) data of beta naphthoflavone abyssinone I, abyssinone III, and voriconazole showed free binding energies of −82.755 kJ/mol, −1924.193 kJ/mol, −1890.335 kJ/mol, and −540.141 kJ/mol, respectively. Frontier molecular orbital (FMO) analysis showed that abyssinone III was the chemically reactive molecule and beta naphthoflavone showed maximum electrophilicity. Molecular electrostatic potential (MEP) analysis portrayed possible nucleophilic‐electrophilic attack areas of the structures. PCA and free energy landscape (FEL) analysis data confirmed the stable conformations between flavonoids and receptor. Abyssinone I and III showed nontoxic behavior. These data confirmed that if we repurpose these flavonoids against primary amoebic meningoencephalitis, it will be beneficial for mankind.

CALCULATION OF THERMODYNAMIC TEMPERATURES OF CHEMICAL REACTIONS OF STEPWISE IRON REDUCTION PROCESS FROM HEMATITE BY SOLID CARBON

The results of thermodynamic analysis of chemical reactions of stepwise reduction of iron from hematite by solid carbon are presented. The aims of the work are to obtain our own expressions for calculating the numerical values of Gibbs free energy depending on temperature using tabular values of standard enthalpies of formation and entropies of inorganic substances, as well as graphical dependences of Gibbs energy on temperature using formulas from literary sources and using the obtained expressions. Numerical values of boundary temperatures are obtained, above which chemical reactions of stepwise reduction of iron from hematite by solid carbon can thermodynamically proceed. It has been established that: the reduction of magnetite (Fe3O4) from hematite (Fe2O3) by solid carbon C is thermodynamically possible above the boundary temperature, the numerical value of which, according to the obtained formula, is 270°; the reduction of wustite (FeO) from magnetite (Fe3O4) by solid carbon C is thermodynamically possible above the boundary temperature, the numerical value of which, according to the obtained formula, is 658°C; the reduction of iron (Fe) from wustite (FeO) by solid carbon C is thermodynamically possible above the boundary temperature, the numerical value of which, according to the obtained formula, is 703°C, and according to formulas, taken from literary sources, is 774°C, 690°C, 680°C and 609°C, respectively, for each formula. Despite the fact that thermodynamics allows all these chemical reactions to occur above the certain above-mentioned temperature values, each of the reactions of stepwise reduction of iron from its oxides by solid carbon in a shaft reduction furnace either occurs at higher temperatures, and, which is quite obvious, with a change in the aggregate state of the reacting (initial) substances or at least one of them (given that FeO forms low-melting compounds with SiO2, this will be the reaction of reduction of iron from wustite), or does not occur at all (given that Fe2O3 and Fe3O4 do not form low-melting compounds with SiO2, and their melting temperatures are greater than 1500°C, these will be the reactions of reduction of magnetite from hematite and reduction of wustite from magnetite).

CALCULATION OF THERMODYNAMIC TEMPERATURES OF CHEMICAL REACTIONS OF STEPWISE MANGANESE REDUCTION PROCESS FROM ITS DIOXIDE BY CO GAS AND GASIFICATION OF SOLID CARBON BY DEGREES OF CHEMICAL AFFINITY OF SUBSTANCES TO OXYGEN

The results of a thermodynamic analysis of the course of chemical reactions of the stepwise reduction of manganese from its dioxide by CO gas and the gasification reaction of solid carbon (Bella-Boudoir) are presented. The goals of the work are to obtain eigenexpressions for calculating the numerical values of the Gibbs free energy depending on temperature using tabulated values of the standard enthalpies of formation and entropies of inorganic substances, as well as to construct graphical dependences of the Gibbs energy on temperature using formulas from literary sources and obtained expressions. Numerical values of the boundary temperatures are obtained above which the chemical reactions of the stepwise reduction of manganese from its dioxide by CO gas and the chemical reaction of gasification of solid carbon (Bella-Boudoir) can or cannot thermodynamically proceed. Considering the complete coincidence of the obtained data on the own (obtained) expressions using two (direct and indirect) methods, it is possible to consider with a significant degree of probability the numerical values of the boundary temperature for the reactions of stepwise reduction of manganese from its dioxide and gasification of solid carbon as reliable, which indicates the possibility of the reduction of Mn2O3 from MnO2, Mn3O4 from Mn2O3 and MnO from Mn3O4 by CO gas, the Bell-Boudoir reaction and the impossibility of the reduction of manganese from MnO by CO gas at the temperatures of the actual process in reduction furnaces. This also confirms that CO gas is not a manganese reducer at the last stage of stepwise reduction of MnO according to scheme (B), refuting any theories and assumptions about the possibility of reducing Mn from MnO by CO gas.

Changes in the structural properties of polycrystalline oxide La<sub>2</sub>O<sub>3</sub> at heating it in air and in vacuum

Changes in the phase’s structure of polycrystalline La2O3 upon heating in air and vacuum have been established. For the first time, on La2O3 samples after annealing in the range 700‒1900 оC in air, the microstructure of a monoclinic phase of type B and a hexagonal phase of type A with the presence of texture was obtained. For the first time, after annealing La2O3 samples at 1900 °C in air, the formation of loops and screw dislocations on La2O3‒х grains was discovered, through which the evaporation of crystals of different colors and the decomposition of hexagonal phase grains into cubic phase crystals of type F with an fcc lattice and type C with a bcc lattice occurred. For the first time, it has been theoretically substantiated and experimentally confirmed that heating lanthanum oxide samples at 1750 and 1900 °C leads to the decomposition of the hexagonal phase of type A with the presence of texture into two cubic phases: type F with the content of anionic vacancies and a crystal lattice parameter a = 0.5677 nm (Fm3m) and type C containing color centers and a = 1.14838 nm (Ia3). The refractive indices of these phases were determined. The energy of formation of anion vacancies in the lattice of the hexagonal phase of type A is calculated and the critical concentration of anion vacancies leading to the decomposition of this phase is determined.

Sustainable synthesis and environmental application of chitosan-Ocimum basilicum leaves-ZnO composite membrane for permanganate ion removal in wastewater treatment.

This study introduces a novel and environmentally friendly method for developing a cross-linked chitosan-Ocimum basilicum leaves-ZnO (ChOBLZnO) composite membrane, specifically designed for the adsorption of permanganate ions (MnO4-) from wastewater. Various characterization techniques, including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET) surface area analysis, were employed to confirm the membrane's synthesis quality, structural integrity, and surface properties crucial for adsorption. The BET analysis revealed a surface area of 228.64 m2/g, indicating a highly porous structure. The membrane exhibited a high adsorption capacity of 142.8mg/g and an outstanding removal efficiency of 98.5%. The adsorption kinetics were best described by the pseudo-second-order model, with a correlation coefficient (R2) of 0.998, while the Freundlich isotherm model provided the most accurate fit for the adsorption behavior, with an R2 of 0.995. Thermodynamic studies indicated that the adsorption process is spontaneous and endothermic, with negative Gibbs free energy and positive enthalpy and entropy values. Reusability tests showed that the ChOBLZnO composite membrane maintained a high removal efficiency across five cycles, with minimal performance loss. These results demonstrate the ChOBLZnO composite membrane's potential as an efficient and sustainable solution for wastewater treatment, offering both high efficiency and durability.

Excess Molar Viscosities and Excess Molar Gibbs Energies of The Mixtures of Tire Pyrolytic Oil + Diesel Fuel at 293.15 K and 303.15 K

Diesel-like fuel mixtures are obtained by blending the pyrolytic oil obtained from the pyrolysis of tires and diesel fuel. The excess thermodynamic properties of blended fuel mixtures give a preliminary idea about the transport, storage and combustion properties of the fuel mixture. In this study, pyrolytic oil and diesel fuel were mixed in different proportions at temperatures of 293.15 K and 303.15 K and their excess molar properties were determined. A positive deviation was observed in the excess molar volume and excess molar Gibbs energy values of the two-component mixture, and a negative deviation was observed in the excess molar viscosity values. Volumetric expansion and flow rate of the mixture were found to be higher at 303.15 K. It has been observed that at low pyrolytic oil concentrations, dispersive and physical forces are dominant between molecules, while at high pyrolytic oil concentrations, π-π interactions are more dominant for the molecules.

Parallel (competitive) reactions of micelle formation and cyclodextrin–surfactant inclusion complex formation in aqueous solution: A consequence of the Gibbs–Duhem equation—invariance of the mass action law and the possibility of determining the equilibrium constant of the inclusion complex

The Gibbs–Duhem equation results in the independence between the standard Gibbs free energy of micelle formation and the standard Gibbs free energy of monocomponent surfactant’s and cyclodextrin’s (CD’s) inclusion complex formation in aqueous solution. The experimental data show that the surfactant’s critical micellar concentration increases in the presence of CD. At a constant temperature, the standard Gibbs free energy of micelle formation remains constant, irrespective of the presence of parallel competitive processes such as inclusion complex formation. This indicates that the critical micellar concentration remains unchanged at the corresponding concentration scale. As a result, the equilibrium constant for surfactant–CD inclusion complex formation can be determined by changing the critical micellar concentration in the presence and absence of CD. A graphical method for determining the equilibrium constant of the inclusion complex is also presented. An analytical approach for analyzing the influence of the formation of the inclusion complex with CD on the formation of the binary mixed micellar pseudophase is presented. Suppose that different values exist for the equilibrium constants of the formation of the inclusion complex for two surfactants from their binary mixture. In this case, there is a change in the initial mole fraction from the initial mixture of surfactants, which should be considered when applying the regular solution theory protocol when determining the parameters of a binary mixed micelle in the presence of CD.

New insight into molecular interactions of surface-active ionic liquid (SAIL) with some biomolecules: Experimental and computational approaches

Understanding the influence of ionic liquids (ILs) on the solubility of biomolecules in aqueous solutions is crucial for designing and optimizing novel biotechnological processes. However, the molecular-level mechanisms underlying this influence remain inconclusive and not fully elucidated. To contribute toward the understanding of molecular interactions between amino acids and ionic liquid in aqueous media, measurements of the densities and speeds of sound for L-serine and glycyl-L-serine in (0.00, 0.005, 0.01, 0.03, and 0.05) mol·kg−1 aqueous solutions of 1-octyl-3-methylimidazolium bromide were conducted at T = (288.15, 298.15, 308.15, and 318.15) K. From experimental data various thermodynamics paramours such as apparent molar volume (Vϕ), the partial molar volume (Vϕ0), standard partial molar volumes of transfer (ΔVϕ0) partial molar isentropic compression (Kϕ,s) and partial molar isentropic compression of transfer (ΔKϕ,S0) have been examined. Along with experiment results, computational tools were also utilized for a deeper understanding of the molecular changes. From density functional theory (DFT), the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) were calculated and utilized to obtain molecular descriptors such as ionization energy (I), electron affinity (A), hardness (η), softness (S), chemical potential (μ), and electronegativity (χ). Thermochemical properties, including change in enthalpy (ΔH), and change in Gibbs free energy (ΔG), were predicted. Molecular docking studies were used to analysis the molecular interaction of ionic liquid with I-Motif structure and structural changes.

Dual active site pathways in cobalt-based bimetallic catalysts enhance oxygen evolution reaction activity: Density functional theory studies

Co single-atom catalysts show significant potential in enhancing oxygen evolution reaction (OER) efficiency, crucial for advancing renewable energy technologies. However, their performance is constrained by a single active site, making it challenging for traditional OER pathways to surpass theoretical overpotential limits. By focusing on dual active sites, this study systematically investigates the structural evolution and catalytic performance of Co based double atom catalysts using density functional theory. Co as the primary metal (M1), pairs with 15 different transition metals (M2) to create bimetallic catalysts. The formation energies, binding energies, and Gibbs free energy changes along four potential OER reaction pathways are calculated to assess the stability and activity of these catalysts. The results show enhanced catalytic performance along path II (H₂O → *OH → *2OH → *OOH → O₂) for Co-Ni, Co-Cu, Co-Pd, and Co-Pt catalysts. This improvement stems from synergistic interactions between metal atoms, bypassing high-energy barriers in traditional pathways. Notably, the d-band centers of Cu, Pd, and Pt near the Fermi level boost electron transfer. Co provides stable adsorption sites, optimizing the conversion of intermediates. This study advances understanding of the reaction mechanism and guides the development of more efficient catalysts.

Eco-friendly corrosion inhibition of steel using phenolic compounds from Cynara syriaca

This study evaluates the corrosion inhibition performance of the n-butanol (n-BuOH) fraction derived from Cynara syriaca on mild steel in acidic environments. The n-BuOH fraction achieved up to 94 % inhibition at 500 ppm, as assessed through gravimetric analysis, potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). Key phenolic compounds, including kaempferol, naringenin, myricetin, chlorogenic acid, and quercetin, were identified by UPLC-MS/MS. These compounds form stable flavonoid-metal complexes, as confirmed by UV–Vis spectroscopy. FT-IR and SEM-EDS analyses revealed the formation of protective coatings and interactions with the steel surface. Polarization curves indicate that the n-BuOH fraction acts as a mixed-type inhibitor, predominantly affecting the anodic reaction. The inhibition efficiency decreased from 93.89 % to 73.43 % with increasing temperatures. Thermodynamic analysis showed an increase in activation energy (Ea = 58.20 kJ/ mol) and a positive ΔH value of 56.17 kJ/mol, which can be attributed to the increased thickness of the double layer, enhancing the activation energy of the corrosion process. A Gibbs free energy (ΔG0ads) value of −25.48 kJ/mol confirms that the adsorption process is spontaneous and involves both physisorption and chemisorption. pKa analysis identified specific adsorption sites. This research underscores the potential of the n-BuOH fraction as a novel, eco-friendly corrosion inhibitor, offering valuable insights for sustainable corrosion control strategies.

Fe2O3/polypyrrole/peanut husk composite for the adsorptive removal of Basic Blue 41 from the aqueous medium: Kinetics, equilibrium modeling and thermodynamic studies

In this study, Basic Blue 41 (BB41) was adsorbed from an aqueous medium using a peanut husk (PH) functional composite with polypyrrole/Fe3O4. For the adsorption of BB41 dye, the effects of process variables including pH, sorbent dose, dye concentration, agitation time, and temperature were investigated. The magnetic composite showed the highest efficiency for the adsorbents at pH 7-10, 0.05 g adsorbent dose, 90 min contact time and 200 mg/L initial dye concentration at 27 °C. The qe was found up to 48 mg/g with percentage removal of up to 96% for BB41 dye for the composite. On the experimental data of BB41 dye, the Langmuir, Freundlich, Temkin, Harkin-Jura, and Dubinin-Radushkevich isotherms were applied. The BB41 adsorption data were also subjected to pseudo-first order, pseudo-second order, and intraparticle diffusion kinetic models. Thermodynamic factors, such as the change in enthalpy (ΔH°), entropy (ΔS°), and Gibbs free energy (ΔG°), were also calculated. The results show that the BB41 adsorption process is exothermic and spontaneous. Techniques such as FT-IR and scanning electron microscopy (SEM) were used to characterize the composite materials. This study demonstrated the promising adsorption potential of magnetic/polypyrrole/peanut husk composites. This class of adsorbent could be used to remediate wastewater that contains dyes.