Enthalpy Energy Research Articles

Quantum cluster equilibrium theory applied to liquid ammonia.

Through this paper, the authors propose using the quantum cluster equilibrium (QCE) theory to reinvestigate ammonia clusters in the liquid phase. The ammonia clusters from size monomer to hexadecamer were considered to simulate the liquid ammonia in this approach. The clusterset used to model the liquid ammonia is an ensemble of different structures of ammonia clusters. After studious research of the representative configurations of ammonia clusters through the cluster research program ABCluster, the configurations have been optimized at the MN15/6-31++G(d,p) level of theory. These optimizations lead to geometries and frequencies as inputs for the Peacemaker code. The QCE study of this molecular system permits us to get the liquid phase populations in a temperature range of 190-260 K, covering the temperatures from the melting point to the boiling point. The results show that the population of liquid ammonia comprises mainly the ammonia hexadecamer followed by pentadecamer, tetradecamer, and tridecamer. We noted that the small-sized ammonia clusters do not contribute to the population of liquid ammonia. In addition, the thermodynamic properties, such as heat of vaporization, heat capacity, entropy, enthalpy, and free energies, obtained by the QCE theory have been compared to the experiment given some relatively good agreements in the gas phase and show considerable discrepancies in liquid phase except the density. Finally, based on the predicted population, we calculated the infrared spectrum of liquid ammonia at 215 K temperature. It comes out that the calculated infrared spectrum qualitatively agrees with the experiment.

Temperature-dependent viscometry of baobab pectin (Adansonia digitata L.)

This study uses the Arrhenius-type equation and the Frenkel-Eyring equation to evaluate the viscosity-temperature dependency of the baobab pectin (BoP) solution at 278.16-353.16 K. The viscosity parameters (apparent viscosity, ηA and intrinsic viscosity, [η]) were analysed for polymeric systems of WEp (pectin extracted using water), AEp (pectin extracted using acid), and Cp (citrus pectin, a control). A Vibro-viscometer was used to measure ηA, while [η] values were estimated from the Kuwara equation. The viscosity parameters decrease with an increase in temperature, though the effects were more pronounced in WEp than in AEp and Cp. Data from [η] indicated that activation energy Ea was higher for AEp (12.24 kJ/mol) and lower for WEp (10.18 kJ/mol). In contrast, the ηA data had a higher Ea for WEp (21.38 kJ/mol) and a lower Ea for Cp (16.49 kJ/mol). The ηA data showed a non-linear viscosity-temperature relationship, and the Vogel-Fulcher-Tammann-Hesse equation was used instead to relate the temperature dependency of BoP. The flow patterns of all pectin solutions showed positive entropy (ΔS + v ), positive enthalpy (ΔH+ v ), and negative Gibbs free energy (ΔG−v ). This revealed that the flow was disordered, dependent on temperature, and spontaneous. Overall, the viscous flow of WEp was more sensitive and less dependent on temperature compared to AEp and Cp.

Capturing CO2 in Quadrupolar Binding Pockets: Broadband Microwave Spectroscopy of Pyrimidine-(CO2)n, n = 1,2.

Pyrimidine has two in-plane CH(δ+)/N̈(δ-)/CH(δ+) binding sites that are complementary to the (δ-/2δ+/δ-) quadrupole moment of CO2. We recorded broadband microwave spectra over the 7.5-17.5 GHz range for pyrimidine-(CO2)n with n = 1 and 2 formed in a supersonic expansion. Based on fits of the rotational transitions, including nuclear hyperfine splitting due to the two 14N nuclei, we have assigned 313 hyperfine components across 105 rotational transitions for the n = 1 complex and 208 hyperfine components across 105 rotational transitions for the n = 2 complex. The pyrimidine-CO2 complex is planar, with CO2 occupying one of the quadrupolar binding sites, forming a structure in which the CO2 is stabilized in the plane by interactions with the C-H hydrogens adjacent to the nitrogen atom. This structure is closely analogous to that of the pyridine-CO2 complex studied previously by (Doran, J. L. J. Mol. Struct. 2012, 1019, 191-195). The fit to the n = 2 cluster gives rotational constants consistent with a planar cluster of C2v symmetry in which the second CO2 molecule binds in the second quadrupolar binding pocket on the opposite side of the ring. The calculated total binding energy in pyrimidine-CO2 is -13.7 kJ mol-1, including corrections for basis set superposition error and zero-point energy, at the CCSD(T)/ 6-311++G(3df,2p) level, while that in pyrimidine-(CO2)2 is almost exactly double that size, indicating little interaction between the two CO2 molecules in the two binding sites. The enthalpy, entropy, and free energy of binding are also calculated at 300 K within the harmonic oscillator/rigid-rotor model. This model is shown to lack quantitative accuracy when it is applied to the formation of weakly bound complexes.

SB‐2 cationic resin: an efficient and reusable organocatalyst for the synthesis of α‐aminophosphonates, DFT calculations and, computer aided design in antifungal activity

AbstractSB‐2 cationic resin has been employed as an unexpected and reusable heterogeneous organocatalyst in multicomponents reaction for the synthesis of the α‐aminophosphonates derivatives that act as antifungal agents, this reaction proceeds under eco‐friendly and simple procedure by condensation in one pot of substituted aromatic aldehydes, anilines and diethylphosphite. Excellent isolated product yields are obtained (up to 70 %) for (4 a–o) within shorter reaction times in solvent‐free condition. The synthesized compounds were determined by spectroscopic analyses such as: NMR (1H, 13C and 31P), IR and HRMS.Molecular geometries, electronic properties, stability and reactivity such as: HOMO/LUMO, , dipole moment (6.1308<D<10.5829), electronegativity (2.3490<X<3.5892), electrophilicity (1.1046<ω<3.2185) and the calculated thermodynamic descriptors (Zero‐point Energies, Enthalpy and Gibbs Free Energy) of four trimethoxy α‐aminophosphonates derivatives (4 j, 4 k, 4 l and 4 m) were carried by DFT at B3LYP 6‐31G (d, p) basis set. Computer aided design by molecular docking of studied compounds revealed a good binding energy against 5HS1 receptor to be considered as antifungal candidates and compared with Voriconazole. In additionally, druglikeness parameters of selected compounds were found through in silico pharmacological ADME/T properties estimation.

Engineering the optical, and dielectric properties of (PVA: PVP)/BaSnO3 polymer nanocomposites as promising films for optoelectronics and energy storage applications

AbstractThis work is devoted to optimizing the optical and dielectric parameters of polyvinyl alcohol (PVA): polyvinyl pyrrolidone (PVP) (1:1) polymer nanocomposites by controlling barium stannate contents (BaSnO3) aspiring to engage it into flexible optoelectronics and thermally stable capacitors. Herein, high purity BaSnO3 was synthesized by solid‐state route and loaded with different ratios (5–20 wt%) into PVA/PVP blend to form films by solution casting method. Further, the degree of crystallinity (Xc) was highly increased upon increasing the filler contents (BaSnO3), as confirmed by X‐ray diffractometer measurement. The surface morphology pictured by a field emission scanning electron microscope revealed the variation of the surface from smooth to rough surface upon insertion of BaSnO3. The thermodynamic parameters including enthalpy (ΔH), entropy (ΔS), and Gibb's free energy (ΔG) were extracted from TGA measurements and studied in detail. The optical characteristics of plain PVA/PVP and polymer nanocomposite films are explored by UV–Vis–NIR spectrophotometer. The presence of charge‐transfer complexes within the polymer nanocomposites was certified via shifting of band gap energy from 5.02 to 4.33 eV and variation of band tailing energy (Eu) from 0.22 to 0.44 eV. The real and imaginary part of optical conductivity (σp1, σp2) was confirmed to be enhanced with the insertion of BaSnO3. It is also found that the dielectric constant and DC current increased with the insertion of BaSnO3 content, while the dielectric loss decreases. The findings recommend these polymer nanocomposites as a good candidate for green energy applications and high‐performance capacitors.

Synthesis, spectroscopic characterisation, DFT insight, and molecular docking studies of a coumarin derivative 3-acetyl-2-oxo-2H-chromene-6-carbohydrazide

In this study, a coumarin derivative, 3-Acetyl-2-oxo-2H-chromene-6-carbohydrazide that could be a new antifungal agent was synthesised, and characterised by elemental analysis, FT-IR, 1H and 13C NMR spectroscopic techniques. DFT calculation data (IR, 1H, and 13C NMR chemical shifts) reveals the good correlation with the experimental values to support the structure of the compound. Molecular geometry, stability, reactivity, and spontaneity were also predicted based on frontier molecular orbitals (FMO), electrostatic potential (ESP) and thermodynamic parameters like entropy, enthalpy, and Gibbs free energy. In addition, molecular docking study results implicate its strong binding (−7.1 to −7.8 kcal/mol) and inhibitory activity against four pathogenic fungal strains A. niger (5GHL), P. chrysogenum (3A72), S. cerevisiae (4G4S), and N. crassa (6MVJ). Thus, this compound may be considered biologically important and serve as a lead for the development of antifungal agents.

Kinetic, Thermodynamic, and Parametric Studies on Batch Synthesis of 1,1‐Diethoxybutane Catalyzed by Amberlyst‐15 Wet

Abstract1,1‐Diethoxybutane is a high‐potential biofuel additive that enhances various fuel properties, which include cetane number, lubricity, biodegradability, and flash point. This work presents a kinetic and thermodynamic study on the acetalization reaction between butanal and ethanol in the presence of Amberlyst‐15 wet in a batch reactor. The experiments were conducted in the temperature range 313–333 K at atmospheric pressure with three different initial molar ratios of reactants and catalyst loadings. An optimal parameter setting to achieve maximum equilibrium conversion of butanal was derived from a parametric study with these three factors. The equilibrium constant for the reaction was determined. Standard thermodynamic properties of the reaction, such as enthalpy, entropy, and Gibbs free energy, were experimentally evaluated. The activity‐based two‐parameter Langmuir‐Hinshelwood‐Hougen‐Watson rate expression was used for reaction kinetics. The activity coefficients were calculated by the UNIFAC method. The kinetic parameters and the activation energy were evaluated from the experimental data. The experimental data and data predicted by the model were found to be in good agreement.

Dopamine adsorption on OH-functionalized metal phthalocyanines [MPc] (M = Mg, Co) in gas and solvent (water, ethanol) medium: A DFT study

The sensing behavior of the neurotransmitter dopamine (DA) on metal phthalocyanines (MPcs), specifically containing cobalt (CoPc) and magnesium (MgPc) in the presence of solvents (water and ethanol), was investigated using density functional theory (DFT). The outcomes of our study demonstrate that both Mg-Pc and Co-Pc exhibit a higher affinity towards dopamine molecules. The negative values of enthalpy and Gibbs free energy and entropy suggest that the adsorption process is exothermic, spontaneous, reversible, and thermodynamically favorable. Further, the charge transfer and conduction capacity of both Mg-Pc and Co-Pc indicate their potential as sensitive materials for dopamine biosensors. Furthermore, the high recovery time and sensitivity indicate both the materials perform exceptionally well in water, as dopamine sensors with slight edges favouring the DA/CoPc complex.

Crystal structure, phase transitions, dielectric and conduction mechanisms of the new long chain organic-inorganic hybrid [(CH2)8(NH3)2]CoCl4

Two dimensional long chain organic inorganic hybrid [NH3(CH2)8NH3]CoCl4, (2C8CoCl) crystallizes in triclinic system, (P1/P 1̅ ), lattice parameters: a = 8.368 Ǻ, b = 12.888 Ǻ, c = 15.045 Ǻ, α = 97.56°, β = 86.82°, γ = 89.82°, Z = 4, d = 1.44 gm cm−3 and V = 1597.3 Ǻ3. Calculated lattice potential energy (ΔUpot) and change of enthalpy (ΔH) are ΔUpot = 1835.01 (kJ mol−1) and ΔH = 425.92 (kJ mol−1) respectively. Thermal study using differential thermal analysis (DTA) and thermogravimetric analysis (TGA) confirm different phase transitions, in the temperature range (300 < T(K) < 500) with onset temperatures at T1 = 401 ± 1 K, T2 = 358.3 K and T3 = 328.9 K, such transitions are reflected in impedance spectroscopy. The transition at T3 corresponds to chain melting. Dielectric constant and ac-conductivity are studied in the temperature range (300 < T (K) < 420) and frequency range (0.11 < f(kHz) < 65). Three different thermally activated conduction regions were observed corresponding to phases I (404–414) K; (ΔEo~ 0.83 eV), II (360–400) K; (ΔEo~ 1.19 eV) and III (T < 348 K); ΔEo = (0.03 eV– 0.006 eV). Equivalent circuit derived from impedance analysis, is composed of combination of resistor and two series of parallel (R//CPE) circuits. Super-linear power law dominates for ac- conduction in the measured temperature ranges. Conduction mechanism is analyzed on the basis of different conduction models which varies as the phases change. Quantum mechanical tunneling prevails at low temperatures with s value ~0.77 while correlated barrier hopping dominates in the range (363 < T (K) < 400) with barrier height WM = 0.34 eV. Comparison to previously studied long chain hybrids [NH3(CH2)nNH3]CoCl4, n = 6 and 7 is discussed. A linear decrease in lattice potential energy and enthalpy values is observed as chain length increases. The room temperature conductivity reveals that σ ac(2C7CoCl) > σ ac(2C6CoCl) >σ ac(2C8CoCl), which is discussed in light of structural characteristics.

Water desorption isotherms and thermodynamic properties of Ora-pro-nóbis (Pereskia aculeata Miller)

Desorption isotherms of ora-pro-nóbis leaves were determined at storage (5 °C, 10 °C, 20 °C, 30 °C, and 40 °C) and drying (40 °C, 50 °C, 60 °C, 70 °C, and 80 °C) temperatures by the gravimetric static method using saturated saline solutions to obtain relative humidities ranging from 5.20% to 98.48%. The net isosteric heat of desorption and thermodynamic properties such as differential enthalpy, differential entropy, and Gibbs free energy were also estimated. The GAB model presented the best parameters of fitting and the lowest Akaike and Bayesian information criteria values. The desorption isotherm patterns presented a sigmoid shape and were categorized as BET Type II sigmoid shape. The monolayer moisture content was estimated in 0.06 kg of water/kg of dry matter using the GAB model, and it remained constant at all temperatures. The leaves presented an optimal water activity equal to 0.35 at storage temperatures. The net isosteric heat of desorption decreased with increasing Xeq, and differential entropy increased with rising equilibrium moisture content (Xeq > 0.07). The enthalpy-entropy compensation was evaluated, and the desorption process is revealed to be entropy-driven and non-spontaneous.

Effect of hydrogen on the mechanical, electronic, and thermodynamic properties of YMgNi4 alloys from first-principles calculations

Using the Density Functional Theory, we investigated the mechanical, electronic, and thermodynamic properties of YMgNi4 alloys and its two hydrides. The results of formation enthalpy and impurity formation energy indicate that an increase in H doping content contributes to the thermodynamic stability of YMgNi4 alloy, and the phonon dispersion curves show that these models are consistent with dynamic stability. Additionally, the elastic modulus Poisson's ratio and AU were studied using the Voigt-Reuss-Hill approximation method. The band structures and density of states confirm their metallic nature. The free energy and heat capacity were also calculated to further investigate the thermodynamic properties.

Hydration of p-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$p-$$\\end{document}aminobenzoic acid: structures and non-covalent bondings of aminobenzoic acid-water clusters

ContextMicro-hydration of the aminobenzoic acid is essential to understand its interaction with surrounding water molecules. Understanding the micro-hydration of the aminobenzoic acid is also essential to study its remediation from wastewater. Therefore, we explored the potential energy surfaces (PESs) of the para-aminobenzoic acid-water clusters, ABWn\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_n$$\\end{document}, n=1-10\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$n=1-10$$\\end{document}, to study the microsolvation of the aminobenzoic acid in water. In addition, we performed a quantum theory of atoms in molecules (QTAIM) analysis to identify the nature of non-covalent bondings in the aminobenzoic acid-water clusters. Furthermore, temperature effects on the stability of the located isomers have been examined. The located structures have been used to calculate the hydration free energy and the hydration enthalpy of the aminobenzoic acid using the cluster continuum solvation model. The hydration free energy and the hydration enthalpy of the aminobenzoic acid at room temperature are evaluated to be −7.0 kcal/mol and −18.1 kcal/mol, respectively. The hydration enthalpy is in perfect agreement with a previous experimental estimate. Besides, temperature effects on the calculated hydration enthalpy and free energy are reported. Finally, we calculated the gas phase binding energies of the most stable structures of the ABWn\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_n$$\\end{document} clusters using twelve functionals of density functional theory (DFT), including empirical dispersion. The DFT functionals are benchmarked against the DLPNO-CCSD(T)/CBS. We have found that the three most suitable DFT functionals are classified in the following order: PW6B95D3 > MN15 > ω\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\omega $$\\end{document}B97XD. Therefore, the PW6B95D3 functional is recommended for further study of the aminobenzoic acid-water clusters and similar systems.MethodsThe exploration started with classical molecular dynamics simulations followed by complete optimization at the PW6B95D3/def2-TZVP level of theory. Optimizations are performed using Gaussian 16 suite of codes. QTAIM analysis is performed using the AIMAll program.

Low‐Electronegativity Mn‐Contraction of PtMn Nanodendrites Boosts Oxygen Reduction Durability

AbstractPlatinum metal (PtM, M=Ni, Fe, Co) alloys catalysts show high oxygen reduction reaction (ORR) activity due to their well‐known strain and ligand effects. However, these PtM alloys usually suffer from a deficient ORR durability in acidic environment as the alloyed metal is prone to be dissolved due to its high electronegativity. Herein, we report a new class of PtMn alloy nanodendrite catalyst with low‐electronegativity Mn‐contraction for boosting the oxygen reduction durability of fuel cells. The moderate strain in PtMn, induced by Mn contraction, yields optimal oxygen reduction activity at 0.53 A mg−1 at 0.9 V versus reversible hydrogen electrode (RHE). Most importantly, we show that relative to well‐known high‐electronegativity Ni‐based Pt alloy counterpart, the PtMn nanodendrite catalyst experiences less transition metals’ dissolution in acidic solution and achieves an outstanding mass activity retention of 96 % after 10,000 degradation cycles. Density functional theory calculation reveals that PtMn alloys are thermodynamically more stable than PtNi alloys in terms of formation enthalpy and cohesive energy. The PtMn nanodendrite‐based membrane electrode assembly delivers an outstanding peak power density of 1.36 W cm−2 at a low Pt loading and high‐performance retention over 50 h operations at 0.6 V in H2‐O2 hydrogen fuel cells.

Low-Electronegativity Mn-Contraction of PtMn Nanodendrites Boosts Oxygen Reduction Durability.

Platinum metal (PtM, M=Ni, Fe, Co) alloys catalysts show high oxygen reduction reaction (ORR) activity due to their well-known strain and ligand effects. However, these PtM alloys usually suffer from a deficient ORR durability in acidic environment as the alloyed metal is prone to be dissolved due to its high electronegativity. Herein, we report a new class of PtMn alloy nanodendrite catalyst with low-electronegativity Mn-contraction for boosting the oxygen reduction durability of fuel cells. The moderate strain in PtMn, induced by Mn contraction, yields optimal oxygen reduction activity at 0.53 A mg-1 at 0.9 V versus reversible hydrogen electrode (RHE). Most importantly, we show that relative to well-known high-electronegativity Ni-based Pt alloy counterpart, the PtMn nanodendrite catalyst experiences less transition metals' dissolution in acidic solution and achieves an outstanding mass activity retention of 96 % after 10,000 degradation cycles. Density functional theory calculation reveals that PtMn alloys are thermodynamically more stable than PtNi alloys in terms of formation enthalpy and cohesive energy. The PtMn nanodendrite-based membrane electrode assembly delivers an outstanding peak power density of 1.36 W cm-2 at a low Pt loading and high-performance retention over 50 h operations at 0.6 V in H2 -O2 hydrogen fuel cells.

High‐temperature phase transformation and thermodynamic properties of Ca3(VO4)2

AbstractCa3(VO4)2 is a promising candidate for applications in ferroelectric, laser host, and optical materials owing to its unique whitlockite structure and excellent physicochemical properties. In this study, the Ca3(VO4)2 powder was fabricated via a conventional solid‐phase route in air, using V2O5 and CaO as precursors. The trigonal Ca3(VO4)2 belongs to the space group R3c, having unit cell parameters of a = 10.8074 Å, b = 10.8074 Å, and c = 37.98871 Å, respectively. Ca3(VO4)2 melts congruently at 1680 K, as determined from differential scanning calorimetry measurements of the thermal profile of the second heating test. Enthalpy changes in Ca3(VO4)2 were experimentally determined for the first time across temperatures between 573 and 1623 K by drop calorimetry. The temperature‐dependent molar heat capacity of Ca3(VO4)2 was calculated from the enthalpy changes at elevated temperatures. Thermodynamic properties (entropy, enthalpy, and Gibbs free energy changes) were also calculated. The thermodynamic properties measured in this study were further applied to evaluate the appropriate precursors for fabricating Ca3(VO4)2 via solid‐state calcination. The results strongly recommend the use of V2O5 and Ca(OH)2 precursors for preparing the Ca3(VO4)2 samples because of their thermodynamic advantages.

Hydrothermal synthesis of eco-friendly ZnO/CNT nanocomposite and efficient removal of Brilliant Green cationic dye

In this study, seeking to get a more efficient adsorbent, comparable to the commercially available adsorbent, is attracting significant interest as a good adsorbent for wastewater treatment. An approach according to the use of ZnO NPs loaded on the surface of carbon nanotube (ZnO/CNT) nanocomposite to adsorb Brilliant green (BG) dye. ZnO/CNT nanocomposite was chemically synthesized by hydrothermal method and the physicochemical properties were analyzed extensively by using several techniques such as as Fourier-Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), Field Emission Scanning Electron Microscopy (FESEM), Energy-Dispersive X-ray spectroscopy, (EDX), Transmission electron microscopy (TEM), and Thermogravimetric analysis TGA. The effect of different parameters on adsorption processes such as equilibrium time, pH of solution, adsorbent dosage as well as initial concentration of dye has been examined. Results show contact time was (2.00 h), based on the outputs, high capacity of adsorption even at higher initial concentration of dye. With regard to the kinetic analysis, a pseudo second order kinetic model could successfully describe the process of adsorption (R2 0.9910). Then, we used Langmuir, Freundlich isotherm models to obtain the best fit, indicating the role of a multilayer formation for adsorption of BG on the ZnO/CNT nanocomposite from an aqueous solution. Also, the best multilayer adsorption capacity of BG reached to 94.29 mg g−1. The change in free energy of Gibbs (ΔG), entropy (ΔS), and enthalpy (ΔH) were calculated from experimental adsorption results. The obtained negative value of (ΔG) and positive value of (ΔH) show spontaneous nature and endothermic nature of the adsorption process. The regenerated adsorbents in the acidic media (pH 4.0) and basic media (pH10.0) for their performance to removal of BG. The best regenerating has been distilled water. Therefore, it suggests that (ZnO/CNT nanocomposite) is an effective adsorbent and friendly environmentally and inexpensive substance for effective elimination of the dye from wastewater effluent.

Enhanced remediation of U(vi) ions from water resources using advanced forms of morphologically modified glauconite (nano-sheets and nano-rods): experimental and theoretical investigations.

Two forms of morphologically transformed glauconite (GL) involved exfoliated nanosheets (EXG) and nanorods (GRs), which were synthesized by facile exfoliating and scrolling modification under sonication. The two advanced forms (EXG and GRs) were applied as enhanced adsorbents for U(vi) ions and compared with using raw glauconite. The developed GRs structure displays higher saturation retention properties (319.5 mg g-1) in comparison with both EXG (264.8 mg g-1) and GL (237.9 mg g-1). This enhancement is assigned to the noticeable increment in the surface area (32.6 m2 g-1 (GL), 86.4 m2 g-1 (EXG), and 123.7 m2 g-1 (GRs)) in addition to the surface reactivity and exposure of effective siloxane groups. This was supported by the steric investigation based on the isotherm basics of the monolayer model of one energy site. The steric functions declared a strong increase in the density of the existing effective uptake receptors throughout the modification stages (GRs (112.1 mg g-1) > EXG (87.7 mg g-1) > 72.5 mg g-1 (GL)). Also, each active site can be filled with 4 U(vi) ions, donating the parallel orientation of these ions and the operation of multi-ionic mechanisms. The energetic functions, either the uptake energy (<13 kJ mol-1) or Gaussian energy (<5 kJ mol-1), validate the retention of U(vi) by physical reactions. These reactions displayed spontaneous properties and exothermic behaviors based on the investigated thermodynamic functions, including entropy, enthalpy, and internal energy. The structures also showed significant recyclability, indicating potential application on a realistic and commercial scale.

Alkylimidazolium-based ionic liquids with tailored anions and cations for CO2 capture.

A systematic investigation was conducted in the present study to determine how various cations and anions affected the solubility of CO2. To investigate the influence of different cations and anions on the solubility of CO2, twelve ILs were synthesized, characterized, and utilized. These ILs comprised five distinct anions (dioctylsulfosuccinate [DOSS], triflouromethanesulfonate [TFMS], dodecylsulfate [DDS], 3-sulfobezoate [SBA], and benzene sulfonate [BS]), and four distinct cations (1-butyl-3-propanenitrile imidazolium [C2CN Bim], 1-hexyl-3-propanenitrile imidazolium [C2CN Him], 1-octyl-3-propanenitrile imidazolium [C2CN Oim], and 1-decyl-3-propanenitrile imidazolium [C2CN Dim]). The synthesized ILs were characterized using NMR and elemental analysis. Their moisture and halide contents were determined. The gravimetric method (MSB) was employed to determine the solubility of CO2 at various pressures (20, 15, 10, 5, and 1 bar). In addition, the effects of temperature on the solubility of CO2 were investigated. The constant of Henry's law (kH) was also calculated, along with thermodynamic properties including standard enthalpy (H0), entropy (S0), and Gibbs free energy (G0).

Thermodynamic analysis of electric field enhanced CO2 capture by moisture-sensitive quaternary ammonium-based sorbents

Climate change incurred by the increasing amount of CO2 released into the atmosphere has become a global priority, and triggers the development of carbon capture, utilization, and storage. Low energy requirement and cost by employing moisture swing process make quaternary ammonium-based materials applicable for CO2 capture. The moisture-sensitive sorbents suffer decreased CO2 affinity and cyclic capacities with moderate or high humidity, while water vapor ubiquitously exists in flue gas or ambient air. The effect of applying electric field on CO2 adsorption, especially the water-involved proton transfer step, by quaternary ammonium-based sorbents in the existence of water, is analyzed. The discrepancy in the hydrophilicity between reactant and product species is enhanced by the electric field, which indicates more favorable chemisorption. Thermodynamics of CO2 adsorption coupling interfacial water evaporation under the electric field are depicted with changes of enthalpy and free energy calculated. Therefore, the rationality of electric field enhanced CO2 capture of quaternary ammonium-based sorbents in moist circumstance is theoretically validated, providing the methodology of optimizing moisture swing adsorption from process intensification apart from material design.

Divergent self-assembly propensity of enantiomeric phenylalanine amphiphiles that undergo pH-induced nanofiber-to-nanoglobule conversion.

This study presents the pathway diversity in the self-assembly of enantiomeric single phenylalanine derived amphiphiles (single F-PDAs), viz.L-NapF-EDA and D-NapF-EDA, that form supramolecular hydrogels at varied concentrations (≥1 mg mL-1 and ≥3 mg mL-1, respectively). By fitting the variable temperature circular dichroism (VT-CD) data to the isodesmic model, various thermodynamic parameters associated with their self-assembly, such as association constant (K), changes in enthalpy (ΔH), entropy (ΔS), and Gibbs free energy (ΔG), were extracted. The self-assembly of these single F-PDAs was found to be enthalpy-driven but entropically-disfavored. Although self-assembly of the D-isomer was slow, it also exhibited greater free energy of association than the L-isomer. Consequently, thermally and mechanically more robust self-assemblies were formed by the D-isomer than the L-isomer. We term these results as the "butterfly effect in self-assembly" wherein the difference in the stereochemical orientation of the residues at a single chiral center present in these molecules resulted in strong differences in the self-assembly propensity as well as in their thermal and mechanical stability. These single F-PDAs form helical nanofibers of opposite chirality upon self-assembly at basic pH (≥8) that produce intense CD signals. However, upon decreasing the pH, a gradual nanofiber-to-nanoglobular transformation was noticed due to protonation-induced structural changes in the PDAs.