Search Results (57)

Isobaric vapor-liquid equilibrium (VLE) data for binary mixtures of biomass–derived ethyl levulinate and ethanol were measured using an apparatus comprising a modified Rose-Williams still and a condensation system. Measurements were taken at temperatures ranging from 329.58 K to 470.00 K and pressures of 40.0, 60.0 and 80.0 kPa. The thermodynamic consistency of the VLE data was evaluated using the Redlich-Kister area test, the Fredenslund test and the Van Ness point-to-point test. The data was correlated using three activity coefficient models: Wilson, NRTL and UNIQUAC. The Gibbs energy of mixing of the VLE data was analyzed to verify the suitability of the binary interaction parameters of these models. The activity coefficients and excess Gibbs free energy, calculated from the VLE experimental data and model correlation results, were analyzed to evaluate the models’ fit and the non–ideality of the binary system. The accuracy of the regression results was also assessed based on the root mean square deviation (RMSD) and average absolute deviation (AAD) for both temperature and the vapor phase mole fraction of ethyl levulinate. The results indicate that the NRTL model provided the best fit to the experimental data. Notably, the experimental data showed strong correlation with the predictions of all three models, suggesting their reliability for practical application. Full article

A novel ruthenium(II) complex, [RuCl₂(η⁶-p-cymene)(bph-κN)] (1), was synthesized and structurally characterized using FTIR and NMR spectroscopy. Density functional theory (DFT) calculations supported the proposed geometry and allowed for comparative analysis of experimental and theoretical spectroscopic data. The interaction of complex 1 with human serum albumin (HSA) and calf thymus DNA was investigated through fluorescence quenching experiments, revealing spontaneous binding driven primarily by hydrophobic interactions. The thermodynamic parameters indicated mixed quenching mechanisms in both protein and DNA systems. Ethidium bromide displacement assays and molecular docking simulations confirmed DNA intercalation as the dominant binding mode, with a Gibbs free binding energy of −34.1 kJ mol⁻¹. Antioxidant activity, assessed by EPR spectroscopy, demonstrated effective scavenging of hydroxyl and ascorbyl radicals. In vitro cytotoxicity assays against A375, MDA-MB-231, MIA PaCa-2, and SW480 cancer cell lines revealed selective activity, with pancreatic and colorectal cells showing the highest sensitivity. QTAIM analysis provided insight into metal–ligand bonding characteristics and intramolecular stabilization. These findings highlight the potential of 1 as a promising candidate for further development as an anticancer agent, particularly against multidrug-resistant tumors. Full article

CoCrFeMoNiSi_x (x = 0.25, 0.50, 0.75) HEACs were successfully prepared on Q235 steel substrates by the plasma cladding method. The phase structure, microstructure, element distribution, and wear and corrosion resistance of these coatings were investigated by XRD, OM, SEM, EDS, a friction and wear tester, and an electrochemical workstation. The results show that the CoCrFeMoNiSi_x (x = 0.25, 0.50, 0.75) coatings are composed of a major FCC phase and minor BCC phase. With an increase in Si content, the lattice constant and cell volume of both phases and the BCC phase content in these alloys gradually increase, while the enthalpy of mixing, Gibbs free energy, atomic radius difference, VEC, and phase density decrease. All the three alloys exhibit typical dendritic structures. With an increase in Si content, the enrichment of Mo and Si in the interdendrite region is significantly reduced. The friction coefficients of CoCrFeMoNiSi_x (x = 0.25, 0.50, 0.75) HEACs show a trend of first increasing, then decreasing, and gradually stabilizing with an increase in time, and are 0.604, 0.526, and 0.534, respectively. The wear resistance of the three alloys is mainly related to the changes in crystallinity and high-strength BCC phase content caused by different Si contents. The polarization curves of CoCrFeMoNiSi_x (x = 0.25, 0.50, 0.75) high-entropy alloy coatings show an obvious passivation zone, and the corrosion resistance is significantly better than that of Q235 steel substrate. The CoCrFeMoNiSi_0.75 coating has the highest self-corrosion potential, smallest self-corrosion current, largest capacitive reactance arc radius, and best corrosion resistance in a 3.5% NaCl solution. Full article

CO₂ flooding plays a crucial role in enhancing oil recovery and achieving carbon reduction targets, particularly in unconventional reservoirs with complex pore structures. The phase behavior of CO₂ and hydrocarbons at different scales significantly affects oil recovery efficiency, yet its underlying mechanisms remain insufficiently understood. This study improves existing thermodynamic models by introducing Helmholtz free energy as a convergence criterion and incorporating adsorption effects in micro- and nano-scale pores. This study refines existing thermodynamic models by incorporating Helmholtz free energy as a convergence criterion, offering a more accurate representation of confined phase behavior. Unlike conventional Gibbs free energy-based models, this approach effectively accounts for confinement-induced deviations in phase equilibrium, ensuring improved predictive accuracy for nanoscale reservoirs. Additionally, adsorption effects in micro- and nano-scale pores are explicitly integrated to enhance model reliability. A multi-scale thermodynamic model for CO₂-hydrocarbon systems is developed and validated through physical simulations. Key findings indicate that as the scale decreases from bulk to 10 nm, the bubble point pressure shows a deviation of 5% to 23%, while the density of confined fluids increases by approximately 2%. The results also reveal that smaller pores restrict gas expansion, leading to an enhanced CO₂ solubility effect and stronger phase mixing behavior. Through phase diagram analysis, density expansion, multi-stage contact, and differential separation simulations, we further clarify how confinement influences CO₂ injection efficiency. These findings provide new insights into phase behavior changes in confined porous media, improving the accuracy of CO₂ flooding predictions. The proposed model offers a more precise framework for evaluating phase transitions in unconventional reservoirs, aiding in the optimization of CO₂-based enhanced oil recovery strategies. Full article

The starting point for the preparation of polymeric membranes by phase inversion is having a thermodynamically stable solution. Ternary diagrams for the polymer, solvent, and non-solvent can predict this stability by identifying the phase separation and describing the thermodynamic behavior of the membrane formation process. Given the lack of data for the ternary system water (H₂O)/hydrochloric acid (HCℓ)/polyamide 66 (PA66), this work employed the Flory–Huggins theory for the construction of the ternary diagrams (H₂O/HCℓ/PA66 and H₂O/formic acid (FA)/PA66) by comparing the experimental data with theoretical predictions. Pure polymer and the membranes produced by phase inversion were characterized to provide the information required to create the ternary diagrams. PA66/FA and PA66/HCℓ solutions were also evaluated regarding their classification as true solutions, and the universal quasi-chemical functional group activity coefficient (UNIFAC) method was used for determining non-solvent/solvent interaction parameters (g₁₂). Swelling measurements determined the polymer/non-solvent interaction parameter (χ₁₃) for H₂O/PA66 and the solvent/polymer interaction parameter (χ₂₃) for PA66/FA and PA66/HCℓ. The theoretical cloud point curve was calculated based on “Boom’s LCP Correlation” and compared to the curve of the experimental cloud point. The ternary Gibbs free energy of mixing and χ₂₃ indicated FA as the best solvent for the PA66. However, for HCℓ, the lower concentration (37–38%), volatility, and fraction volume of dissolved PA66 (ϕ₃) indicated that HCℓ is also adequate for PA66 solubilization based on the similar membrane morphology observed when compared to the PA66/FA membrane. Full article

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. Full article

In this paper, we developed models for 21 quinary high-entropy transition metal carbide ceramics (HETMCCs), composed of carbon and the transition metals Ti, Zr, Mo, V, Nb, W, and Ta, employing the Special Quasirandom Structures (SQS) method. We investigated how the transition metal elements influence lattice distortion, mixing enthalpy, Gibbs free energy of mixing, and the electronic structure of the systems through first-principles calculations. The calculations show that 21 systems can form a stable single phase, among which (TiMoVNbTa)C₅, (ZrMoNbWTa)C₅, and (MoVNbWTa)C₅ exhibit superior stability. The formation energy and migration energy of carbon vacancies in systems with strong single-phase stability were calculated to predict their radiation resistance. The formation energy of carbon vacancies is closely related to the types of surrounding transition metal elements, with values ranging between the maximum and minimum formation energies observed in binary transition metal carbides (TMCs). The range of migration energy for carbon vacancies is wider than that observed in TMCs, which can hinder their long-range migration and enhance the radiation resistance of the materials. Full article

This review provides a critical assessment of the current state of affairs regarding the solvation thermodynamics involving mixed-solvent systems. It focuses specifically on (i) its rigorous molecular-based foundations, (ii) the underlying connections between the microstructural behavior of the mixed-solvent environment and its thermodynamic responses, (iii) the microstructural characterization of the behavior of the mixed-solvent environment around the dilute solute via unique fundamental structure-making/-breaking functions and the universal preferential solvation function, (iv) the discussion of potential drawbacks associated with the molecular simulation-based determination of thermodynamic preferential interaction parameters, and (v) the forensic examination of frequent modeling pitfalls behind the interpretation of preferential solvation from experimental data of Gibbs free energy of solute transfer. Full article

The corrosion protection property of three Brij-type surfactants, namely, Brij 35, Brij 56 and Brij 58P, was considered on OLC 45 carbon steel in a 0.5 M H₂SO₄ medium. The efficacy for these organic compounds was examined using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods, scanning electron microscopy (SEM) procedures, and Fourier transform infrared (FT-IR) spectroscopy. We hypothesized that these surfactants hinder the corrosion for OLC 45 samples through a protecting mechanism owing to the adsorption of organic molecules that form an inhibitive film or through the formation of complex oxides. These surfactants exhibited an appreciable protective effect against OLC 45 corrosion, operating as mixed inhibitors, as could be demonstrated by their influence on the electrochemical characteristics of the metallic substrates. The adsorption of surfactants over the substrates zone conformed to the representation of the Langmuir isotherm. The effect of temperature on the electrochemical comportment of the OLC 45 specimens in H₂SO₄ without and with Brij at 800 ppm was examined in the temperature interval of 293 to 333 K. The negative estimate of thermodynamic attributed as Gibbs free energy of adsorption presented the spontaneity of the adsorption activity. The investigation with FT-IR and SEM established the adsorption of Brij and the constitution of the corrosive components on the OLC 45 surface. Electrochemical determinations of these surfactants indicated its anticorrosion inhibition performance and the highest inhibition of 96% was reached when the Brij 35 concentration was at 800 or 1000 ppm, while for Brij 56 and Brij 58P, the highest inhibition was obtained when their concentrations were 500, 800, or 1000 ppm. Full article

Rare Earth Elements (REE) phosphates (monazite, xenotime, and rhabdophane) are critical REE-bearing minerals typically formed in hydrothermal and magmatic ore deposits. The thermodynamic properties of those REE minerals are crucial to understanding the solubility, speciation, and transport of REE complexes. However, the standard-state Gibbs free energy of formation (∆G°_f) values reported for these minerals in the literature vary by up to 25 kJ mol⁻¹. Here, we present linear free energy relationships that allow the evaluation and estimation of the ∆G°_f values at 25 °C and 1 bar for the three minerals from the ionic radius (r_REE³⁺) and the non-solvation Gibbs free energy contribution to the REE³⁺ aqua ion (∆G°_{n, REE}³⁺): ∆G°_f,monazite − 399.71 r_REE³⁺ = 1.0059 ∆G°_n,REE³⁺ − 2522.51; ∆G°_f,xenotime − 344.08 r_REE³⁺ = 0.9909 ∆G°_n,REE³⁺ − 2451.53; and ∆G°_{f,rhabdophane} − 416.17 r_REE³⁺ = 1.0067 ∆G°_{n, REE}³⁺ − 2688.86. Moreover, based on the new dataset derived for REE end-members, we re-fitted the binary Margules parameter (W) from previous theoretical calculations into linear correlations: W + 0.00204 ∆G°^’_n,monazite = 39.3549 ∆V + 0.0641; W + 0.00255 ∆G°^’_n,xenotime = 25.4885 ∆V − 0.0062. The internally consistent thermodynamic properties of these REE phosphates are incorporated into the computer program Supcrtbl, which is available online at Zhu’s research website. Full article

From the examples of three and four-component polymer–polymer systems characterized by amorphous separation, an original technique for determining the pair parameters of interaction between components based on the sorption isotherms of common solvent vapor, particularly water vapor, has been developed. The possibility of calculating thermodynamic characteristics of multicomponent polymer compositions with specific interactions of functional groups from experimentally obtained sorption isotherms is shown. An algorithm for calculating pair interaction parameters, estimating concentration dependences of chemical potential and Gibbs free energy of mixing, and predicting the phase state of polymer mixtures was presented for the first time for such systems. The technique was tested on the example of systems poly(N-vinylpyrrolidone) (PNVP)–polyethylene glycol (PEG), PNVP–PEG–Poly(acrylic acid) (PAA), poly(N-vinylcaprolactam) (PNVCL)–PEG, and polyvinyl alcohol (PVA)–PEG. Full article

This study reports the interfacial phenomenon of cefotaxime in combination with nonionic surfactants, Triton X-100 (TX-100) and Tween-80 (TW-80), and their mixed micellar formulations. Cefotaxime was enclosed in a micellar system to improve its solubility and effectiveness. TX-100 and TW-80 were used in an amphiphilic self-assembly process to create the micellar formulation. The effect of the addition of TX-100, a nonionic surfactant, on the ability of TW-80 to solubilize the drug was examined. The values of the critical micelle concentration (CMC) were determined via UV-Visible spectroscopy. Gibbs free energies (ΔG_p and ΔG_b), the partition coefficient (K_x), and the binding constant (K_b) were also computed. In a single micellar system, the partition coefficient (K_x) was found to be 33.78 × 10⁶ and 2.78 × 10⁶ in the presence of TX-100 and TW-80, respectively. In a mixed micellar system, the value of the partition coefficient for the CEF/TW-80 system is maximum (5.48 × 10⁶) in the presence of 0.0019 mM of TX-100, which shows that TX-100 significantly enhances the solubilizing power of micelles. It has been demonstrated that these surfactants are effective in enhancing the solubility and bioavailability of therapeutic compounds. This study elaborates on the physicochemical characteristics and solubilization of reactive drugs in single and mixed micellar media. This investigation, conducted in the presence of surfactants, shows a large contribution to the binding process via both hydrogen bonding and hydrophobic interactions. Full article

Pharmaceutical, food, and cosmetic formulations often contain binary or ternary surfactant mixtures with synergistic interactions amongst micellar building blocks. Here, a ternary mixture of the surfactants hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, and sodium deoxycholate is examined to see if the molar fractions of the surfactants in the ternary mixed micellar pseudophase are determined by the interaction coefficients between various pairs of the surfactants or by their propensity to self-associate. Critical micelle concentrations (CMC) of the analyzed ternary mixtures are determined experimentally (spectrofluorimetrically using pyrene as the probe molecule). Thermodynamic parameters of ternary mixtures are calculated from CMC values using the Regular Solution protocol. The tendency for monocomponent surfactants to self-associate (lower value of CMC) determines the molar fractions of surfactant in the mixed micelle if there is no issue with the packing of the micelle building units of the ternary mixed micelle. If a more hydrophobic surfactant is incorporated into the mixed micelle, the system (an aqueous solution of surfactants) is then the most thermodynamically stabilized. Full article

In this present study, the potential application of DCMFC for the treatment of three different sourced industrial wastewater streams: biorefinery, dairy and mixed streams was investigated. Operating conditions were optimised using the Box Behnken design in response surface methodology (RSM) with three validation experimental runs. The effect of process variables, i.e., HRT (48 h), catholyte dose (0.1 gmol/L) and electrode surface area (three carbon rods argumentation-m²) on the production of electricity as voltage yield (mV), power density (mW/m²), current density (mA/m²), Columbic efficiency (%) CE and Gibbs free energy correlation with the electromotive force of the DCMFC system. Experimental results obtained were a positive response towards the predictive values according to the DoE numerical optimisation sequence. At numerical optimum MFC conditions stated above, validation experimental responses of voltage yield by biorefinery wastewater were 645.2 mV, mixed wastewater was 549 mV, and dairy wastewater was 358 mV maximum yields. The power densities and current densities were attained, for biorefinery, mixed wastewater and dairy wastewater sources respectively as; 62 mW/m², 50 mW/m² and 27.2 mW/m², then current densities of 50 mA/m², 44,008 mA/m² and 18 mA/m². The coulombic efficiencies of 0.34%, 0.75% and 0.22%, respectively, were achieved. The validation of predicted optimum operating conditions was successfully attained, especially through the biorefinery wastewater organic substrate. This article articulates that it is highly imperative to choose the most suitable wastewater source as the viable electron donor towards scaling up and maximising the efficiency of generating electricity in the double chamber microbial fuel cell (DCMFC). Moreover, the findings of the current study demonstrate that the DCMFC can be further upscaled through a series connection in a fed-batch mode of operation using a well-designed and simulated process control system that has been computationally designed and modelled using first order MFC model bioenergy generating models MATLAB Simulink and Simscape electrical software. These findings of the simulations were successful and illustrated that an MFC power output can be successfully stepped to be a viable bio-electrochemical technology for both industrial wastewater (IWW) treatment and simultaneous sustainable power generation. Full article

This study was aimed at establishing the interactions prevailing in an anionic surfactant, sodium dodecyl sulfate, and dopamine hydrochloride in an alcoholic (ethanol) media by using volumetric, conductometric, and tensiometric techniques. Various methods were utilized to estimate the critical micelle concentration (cmc) values at different temperatures. The entire methods yielded the same cmc values. The corresponding thermodynamic parameters viz. the standard free energy of micellization ($G_{mic}^o$), enthalpy of micellization ($H_{mic}^o$), and entropy of micellization ($S_{mic}^o$) were predicted by applying the pseudo-phase separation model. The experimental density data at different temperatures (298.15 K, 303.15 K, 308.15 K, and 313.15 K) were utilized to estimate the apparent molar volumes ($V_{\varphi }^o$) at an infinite dilution, apparent molar volumes ($V_{\phi }^{cmc}$) at the critical micelle concentration, and apparent molar volumes ($\mathsf{\Delta }{V}_{\phi }^m$) upon micellization. Various micellar and interfacial parameters, for example, the surface excess concentration (${\mathsf{\Gamma }}_{\max }$), standard Gibbs free energy of adsorption at the interface ($\mathsf{\Delta }{G}^o{}_{ad}$), and the minimum surface area per molecule ($A_{\min }$), were appraised using the surface tension data. The results were used to interpret the intermolecular interactions prevailing in the mixed systems under the specified experimental conditions. Full article