Free Energy Change Research Articles

Interpretation of Hydrogen/Deuterium Exchange Mass Spectrometry.

This paper sheds light on the meaning of hydrogen/deuterium exchange-mass spectrometry (HDX-MS) data. HDX-MS data provide not structural information but dynamic information on an analyte protein. First, the reaction mechanism of backbone amide HDX reaction is considered and the correlation between the parameters from an X-ray crystal structure and the protection factors of HDX reactions of cytochrome c is evaluated. The presence of H-bonds in a protein structure has a strong influence on HDX rates which represent protein dynamics, while the solvent accessibility only weakly affects the HDX rates. Second, the energy diagrams of the HDX reaction at each residue in the presence and absence of perturbation are described. Whereas the free energy change upon mutation can be directly measured by the HDX rates, the free energy change upon ligand binding may be complicated due to the presence of unbound analyte protein in the protein-ligand mixture. Third, the meanings of HDX and other biophysical techniques are explained using a hypothetical protein folding well. The shape of the protein folding well describes the protein dynamics and provides Boltzmann distribution of open and closed states which yield HDX protection factors, while a protein's crystal structure represents a snapshot near the bottom of the well. All biophysical data should be consistent yet provide different information because they monitor different parts of the same protein folding well.

Various investigations of ameliorative role of Ashwagandha seeds (Withania somnifera) against amoxicillin toxicity.

Several studies showed the adverse effects of amoxicillin on various body organs. So, this research has been designed to evaluate the modulatory role of Ashwagandha seed extract (ASE) against amoxicillin (AM) toxicity. Rats treated with AM (90mg/kg), protected by ASE doses (100, 200 and 300mg/kg), and treated by ASE at the same three doses. At the end of the experimental period, DNA comet assay, cytogenetic examinations, sperm-shape analysis, evaluation of the malondialdehyde (MDA) percentages, histopathological examinations, and biophysical tests (modulus, relaxation time, permittivity, entropy, and internal energy change of brain) were documented. The results confirmed that AM treatment induced significant elevation of DNA damage, cytogenetic aberrations, and MDA content in brain, liver, and testis tissues and sperm-shape anomalies. ASE treatment significantly minimized the genetic changes, sperm-shape anomalies, and MDA generation. These enhancements were more pronounced by protective ASE and increased by increasing the dose level. In histopathological examinations, AM treatment caused neurotoxicity in brain tissue. ASE treatment, partially, minimized these damages and the positive effects of therapeutic ASE were more noticeable. Biophysical parameters showed that therapeutic ASE was better for relaxation time, permittivity, and free energy change. Protective and therapeutic ASE were able to recover entropy and internal energy changes in variant degrees.

Oxidation mechanism of iodate to metaperiodate on a tungsten trioxide photoanode

The mechanisms involved in the photoelectrochemical oxidation of iodate (IO3−) to metaperiodate (IO4−) and H2O to O2 on WO3 were investigated using density functional theory. The oxygen evolution reaction (OER) included four proton-coupled electron transfer (PCET) steps via H2O2 intermediates. After the first PCET of the rate-limiting step, instead of H2O adsorption, IO3− was adsorbed and the second PCET step generated IO4− species (PI1 mechanism). Although another mechanism, PI2, with the two PCET steps followed by the IO3− adsorption was found, IO4− was energetically generated via PI1 rather than via PI2. Based on the free energy changes in the PCET steps, alkaline cations such as Li+, Na+, and K+ on WO3 suppressed the OER process. In addition, Na+ promoted the IO3− adsorption and subsequent PCET step of PI1. The computational results verified that using NaIO3 aqueous solution on WO3 effectively inhibits OER and facilitates IO4− generation, resulting in a higher (lower) selectivity of IO4− (O2) than using LiIO3 and KIO3 aqueous solutions.

Computational Study of Designed Peptide Analogs against Pseudomonas aeruginosa as a Possible Inhibitor of LptD Membrane Protein

Background: Pseudomonas aeruginosa is a common cause of nosocomial infection worldwide and is responsible for 18-61% of deaths alone. The organism has gained resistance to many known antibiotics and evolved into a multidrug-resistant strain. The LptD outer membrane protein of P. aeruginosa is a special target of interest due to its role in outer membrane biogenesis. Objective: The study aimed to gain an insight into how mutations affect the overall properties of antimicrobial peptides and to identify novel peptide analogs against P. aeruginosa. Methods: The peptide analogs were designed and shortlisted based on physicochemical parameters and estimated free energy change in the current study. The docking studies for wild type and shortlisted peptides were performed against LptD protein of P. aeruginosa. The toxicity, allergenicity, and solubility analyses of peptide analogs with high binding affinity to LptD were also conducted. Results: The molecular docking results indicated that peptide analogs 523M26, 523M29, 523M34, and 523M35 for AP00523 (wild type); 608M12, 608M13, 608M19, 608M31, 608M32, 608M39, and 608M43 for AP00608 (wild type); and 2858M25 for AP02858 (wild type) bound effectively with LptD membrane than their wild types. The toxicity, allergenicity, and solubility analyses revealed all these peptide analogs to be nontoxic, non-allergen, and have good water solubility. Conclusion: The binding energies predicted 523M26, 608M39, and 2858M25 bind effectively to LptD proteins than their wild type. Based on docking analysis, it was further predicted that 608M39 has an estimated binding affinity greater than L27-11, which is a known peptidomimetic inhibitor of the LptD protein.

Bis(dimethylpyrazolyl)-aniline-s-triazine derivatives as efficient corrosion inhibitors for C-steel and computational studies.

4,6-Bis(3,5-dimethyl-1H-pyrazol-1-yl)-N-phenyl-1,3,5-triazin-2-amine (PTA-1), N-(4-bromophenyl)-4,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)-1,3,5-triazin-2-amine (PTA-2) and 4,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)-N-(4-methoxyphenyl)-1,3,5-triazin-2-amine (PTA-3) were synthesized and characterized. Their corrosion inhibition of carbon C-steel in 0.25 M H2SO4 was studied by electrochemical impedance. The inhibition efficiency (IE%) of triazine was superior due to the cumulative inhibition of triazine core structure and pyrazole motif. Potentiodynamic polarizations suggested that s-triazine derivatives behave as mixed type inhibitors. The IE% values were 96.5% and 93.4% at 120 ppm for inhibitor PTA-2 and PTA-3 bearing -Br and -OCH3 groups on aniline, respectively. While PTA-1 without an electron donating group showed only 79.0% inhibition at 175 ppm. The adsorption of triazine derivatives followed Langmuir and Frumkin models. The values of adsorption equilibrium constant K°ads and free energy change ΔG°ads revealed that adsorption of inhibitor onto steel surface was favoured. A corrosion inhibition mechanism was proposed suggesting the presence of physical and chemical interactions. Density functional theory computational investigation corroborated nicely with the experimental results. Monte Carlo simulation revealed that the energy associated with the metal/adsorbate arrangement dE ads/dN i, for both forms of PTA-2 and PTA-3 with electron donating groups (-439.73 and -436.62 kcal mol-1) is higher than that of PTA-1 molecule (-428.73 kcal mol-1). This aligned with experimental inhibition efficiency results.

Theoretical insights on 3D transition metal anchored poly[5,10,15,20-tetra(4-ethynylphenyl)porphyrin]diyne as highly efficient bifunctional catalyst toward ORR and OER

Searching for highly active oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts is a challenging task in the development of clean energy devices. Herein, by using the poly[5,10,15,20-tetra(4-ethynyl-phenyl)porphyrin]diyne (TEPPD), we designed ORR and OER catalysts by anchoring 3d transition metal into TEPPD (TM@TEPPD, TM = Mn-Zn). Our study indicated that Fe@TEPPD is the best bifunctional catalyst for both ORR and OER. By proposing a proper descriptor, Ni-N3@TEPPD (Ni is only coordinated with three N atoms) is designed and also predicted to be a promising bifunctional catalyst. For Fe@TEPPD, ORR and OER become inactive when the acetylene bond in TEPPD is broken. The surface Pourbaix diagram indicated that on the surface of Fe@TEPPD, ORR and OER can be carried out at the whole pH region due to the high dissolution potential of Fe2+. For Ni-N3@TEPPD, however, the dissolution potential 0.71 V for Ni2+is low. Thus, for Ni-N3@TEPPD, ORR can be carried out only after pH>2.54, while OER is not likely at the whole pH region. This suggested that the conclusions from the free energy changes at URHE=0 and pH=0 could be different when different potentials and pH values are considered.

Highly selective electrocatalytic CO2 reduction to multi-carbon products at CuPd synergistic sites over OD-Cu based catalysts

CO2 reduction is a potential way to kill two birds with one stone by converting greenhouse gas into fuels through clean energy. Cu-based catalysts, with a wide range of products, often have limited selectivity and low activity for specific products. In this study, Cu2O was used as the oxide-derived copper (OD-Cu) substrate, which was loaded with CuPd nanoparticles by using pulsed potential and galvanic replacement. Theoretical calculations revealed that the strong H-affinity Pd sites can reduce the selectivity of formate by stabilizing *COOH and simultaneously lowering the d-band center of neighboring Cu. Additionally, the asymmetric C–C coupling of *CHO+*CO, distributed between Cu and Pd sites, can lower the free energy change of rate-determining step to promote production of the C2+ products. Faradaic efficiency (FE) of the C2+ products over Cu2O-CuPd0.5μM was more than three times higher than that over untreated Cu2O NW, rising from 16.50 % to 54.47 % under −1 V (vs RHE) bias. Moreover, the FE for formate and CO decreased respectively from 28.57 % and 19.30 % to 3.69 % and 11.82 %, accompanied by a simultaneous increase in current density by 71.49 %.

Chemical Repair of Radical Damage to the GC Base Pair by DNA-Bound Bisbenzimidazoles.

The migration of an electron-loss center (hole) in calf thymus DNA to bisbenzimidazole ligands bound in the minor groove is followed by pulse radiolysis combined with time-resolved spectrophotometry. The initially observed absorption spectrum upon oxidation of DNA by the selenite radical is consistent with spin on cytosine (C), as the GC• pair neutral radical, followed by the spectra of oxidized ligands. The rate of oxidation of bound ligands increased with an increase in the ratio (r) ligands per base pair from 0.005 to 0.04. Both the rate of ligand oxidation and the estimated range of hole transfer (up to 30 DNA base pairs) decrease with the decrease in one-electron reduction potential between the GC• pair neutral radical of ca. 1.54 V and that of the ligand radicals (E0', 0.90-0.99 V). Linear plots of log of the rate of hole transfer versus r give a common intercept at r = 0 and a free energy change of 12.2 ± 0.3 kcal mol-1, ascribed to the GC• pair neutral radical undergoing a structural change, which is in competition to the observed hole transfer along DNA. The rate of hole transfer to the ligands at distance, R, from the GC• pair radical, k2, is described by the relationship k2 = k0 exp(constant/R), where k0 includes the rate constant for surmounting a small barrier.

Hot Carrier Controlled Nitrogen Fixation Reaction in Metal-Free Boron-Anchored Aza-COF: Insight from Nonadiabatic Molecular Dynamics Simulation.

Designing highly efficient photocatalysts for the production of renewable energy is a challenging task that necessitates simultaneous control of chemical activity and photocarrier dynamics for a particular reaction. To this end, we have investigated the catalytic mechanism and real-time photocarrier dynamics of the nitrogen reduction reaction (NRR) at the metal-free boron-functionalized 2D aza-COF (B-aza-COF), an inexpensive and environmentally friendly semiconductor. By employing density functional theory (DFT) and time-dependent ab initio nonadiabatic molecular dynamics simulation, we have investigated the electronic structure, light harvesting ability, free energy change, and dynamics of photoexcited carriers. Our calculated results reveal that the gas phase N2 molecule can be effectively reduced into NH3 on B-aza-COF under UV-visible light. Therefore, our investigation on the design of efficient photocatalysts for the nitrogen reduction reaction (NRR) provides a cost-effective opportunity for the sustainable production of NH3.

Elucidating the Mechanism of Copper-Induced Photoluminescence Quenching in 2-Phenylbenzimidazole-5-Sulfonic Acid.

To explore the possible impact of 2-Phenylbenzimidazole-5-sulfonic acid (PBSA) on the function of a sunscreen, in this work we investigate the binding of copper metal ions (Cu2+) to PBSA. Due to the existence of an intrinsic interaction phenomenon between Cu2+ ions and PBSA molecules, the photoluminescence (PL) quenching arises owing to the charge transfer from PBSA to Cu2+ ions. The mechanism of fluorescence quenching is probed experimentally following excitation at 306 nm by evaluating various quenching parameters with the help of the Stern-Volmer plot. Through the assessment of the values of the Stern-Volmer constant ( ) and bimolecular quenching rate constant ( ), it is deduced that the dynamic mode of PL quenching is operative between PBSA and Cu2+ ions. We evaluate the number of binding sites (n = 1) that advocate the presence of a single binding site in PBSA for Cu2+ ions. The numerical value of standard Gibbs free energy change, ~ -27.485 kJ.mol-1 implies the spontaneous binding between Cu2+ ions and PBSA molecules. The results obtained give an insight into the mechanism of metal-induced PL quenching of water soluble PBSA sunscreen.

Solubilization study of antihypertensive drug Irbesartan in EO-PO based polymeric nanomicelle and optimization of its release behavior

Irbesartan (IRB) has low bioavailability due to its poor aqueous solubility and dissolution rate, thereby making it imperative to understand their absorption behavior. The present research work is aimed for improvement of solubilization of IRB, by investigating the effect of molecular characteristics/hydrophobicity of Pluronic® copolymers; P84 and F108 micelles with and without added salt (NaCl). The solubility of IRB was increased with copolymer concentration. Effect of added salt (NaCl) showed completely opposite behavior for both the copolymers; where F108 with NaCl has adverse effect on IRB solubilization and considerable decrease was observed. The micelle/water partition coefficient and the standard free energy change (∆G◦) were also evaluated from thermodynamic view point. The in vitro release kinetics of IRB drug was carried out for 1% P84 with and without 1 M NaCl and compared with its release in water. It was found that P84/NaCl reduces the release rate more efficiently for IRB compared to other systems. There are few reports about the solubilization improvement of IRB; but this is the first time where the study of Pluronic® micelle carried out for IRB solubilization with varying solvent condition as per best of our knowledge. This information can be useful to understand the solubilization behaviour of Pluronic® copolymers available in varieties of molecular weights and can be used to identify possible solvent condition for newer applications of Pluronic® copolymers in pharmaceutical field.

Neem biomass derived carbon quantum dots synthesized via one step ultrasonification method for ecofriendly methylene blue dye removal

This article presents a one-step ultrasonication technique for generating biomass carbon dots (BCDs) from neem bark (Azadirachta indica) powder. The BCDs were characterized using modern techniques such as UV–Vis, FTIR, Raman, XRD, HRTEM, FESEM, EDAX, and Zeta potential analyses. Unlike traditional nanocomposite bed systems, this study utilized BCDs as a liquid-phase adsorbent for the regenerative adsorption of the environmentally harmful dye, methylene blue (MB), through an in-situ precipitation reaction. This involved the formation of BCDs-MB adduct via an electrostatic mechanism. The adsorption capacity and percentage of removal were remarkable at 605 mg g–1 and 64.7% respectively, exceeding various solid-based adsorption methods in the literature. The Langmuir isotherm and pseudo-second-order kinetics model provided an excellent fit for this system. The calculated thermodynamic parameter, Gibbs free energy change (ΔG) was negative, indicating a spontaneous, exothermic, and physisorption-based mechanism. The regenerative capacity of our system was further demonstrated by successfully extracting and recovering the MB dye (64%) using ethyl alcohol as the solvent. This method provides an efficient means of recovering valuable cationic organic dye compounds from contaminated environments.

Surface-active ionic liquids as drug carriers: A physico-chemical study

This work evaluates the potential of two surface active ionic liquids (SAILs) 1-dodecyl-3-methylimidazolium bromide and 1-tetradecyl-3-methylimidazolium bromide as drug carrier for ciprofloxacin (CPF) and compares them with their conventional counterparts dodecyltrimethylammonium bromide and tetradecyltrimethylammonium bromide using spectroscopic and electrochemical techniques. Different physico-chemical parameters including critical micelle concentration (CMC), binding constants, partition coefficients and their corresponding free energy changes, thermodynamic parameters of micellization and redox behavior of micelle-drug systems were investigated. Both the SAILs demonstrated higher solubilization powers and binding constants owing to the less polar nature of imidazolium ring. Lower CMCs indicated relatively stronger hydrophobic forces existing in all SAILs-CPF systems tested. The cyclic voltammetry displayed shifting of oxidation peaks towards higher positive potential in the micellar region indicating the protection of CPF against oxidation. This work demonstrates the benefits of using SAILs as drug carriers due to their lower CMCs, improved binding and partition coefficients, and favorable electrochemical results.

Exploring the influence of invasive weed biochar on the sorption and dissipation dynamics of imazethapyr in sandy loam soil.

The management of invasive weeds on both arable and non-arable land is a vast challenge. Converting these invasive weeds into biochar and using them to control the fate of herbicides in soil could be an effective strategy within the concept of turning waste into a wealth product. In this study, the fate of imazethapyr (IMZ), a commonly used herbicide in various crops, was investigated by introducing such weeds as biochar, i.e., Parthenium hysterophorus (PB) and Lantana camara (LB) in sandy loam soil. In terms of kinetics, the pseudo-second order (PSO) model provided the best fit for both biochar-mixed soils. More IMZ was sorbed onto LB-mixed soil compared to PB-mixed soil. When compared to the control (no biochar), both PB and LB biochars (at concentrations of 0.2% and 0.5%) increased IMZ adsorption, although the extent of this effect varied depending on the dosage and type of biochar. The Freundlich adsorption isotherm provided a satisfactory explanation for IMZ adsorption in soil/soil mixed with biochar, with the adsorption process exhibiting high nonlinearity. The values of Gibb's free energy change (ΔG) were negative for both adsorption and desorption in soil/soil mixed with biochar, indicating that sorption was exothermic and spontaneous. Both types of biochar significantly affect IMZ dissipation, with higher degradation observed in LB-amended soil compared to PB-amended soil. Hence, the findings suggest that the preparation of biochar from invasive weeds and its utilization for managing the fate of herbicides can effectively reduce the residual toxicity of IMZ in treated agroecosystems in tropical and subtropical regions.

The impact of plasticisers on crystal nucleation, growth and melting in linear polymers

Plasticisers are often added to crystallising polymers to improve their processability. Despite many experimental studies, very few modelling studies have been performed to provide fundamental understanding of the impact of plasticisers on polymer cyrstallisation kinetics and thermodynamics. In this work, molecular dynamics simulations are used to study crystallisation in a model linear polymer with plasticiser. We first demonstrate that the plasticiser lowers the amorphous phase glass transition, with the extent of the effect increasing with plasticiser concentration, due to increased polymer mobility. Using a model filler surface to induce crystallisation, we find that the plasticiser also reduces crystallisation and melting temperatures. Furthermore, we find that the plasticiser is expelled from the crystals during growth so that its concentration in the amorphous matrix increases with degree of crystallisation. This has a pronounced consequence for crystal melting, and we find a broad temperature range where the crystal is in equilibrium with the amorphous phase, which we rationalise in terms of free energy changes. This has potentially important consequences for the processing of linear polymers such as polyhydroxybutyrate (PHB), poly(l-lactic acid) (PLLA) and polyvinyl alcohol (PVA), by providing the opportunity for processing the polymer in a semicrystalline rather than fully amorphous state.

Adsorption Isotherms and Thermodynamics of <i>Thymol Blue</i> Removal from Aqueous Solution Using Native Pear (<i>Dacryodes edulis</i>) Seed Biomass

The release of dyes into watercourses not only upsets their beautiful nature but also hinders the transmission of sunlight into streams, reducing photosynthesis and resulting in the loss of aquatic life and reduction of water quality. Therefore, there is need to remove such colored substances. One of such dyes is thymol blue. This study was conducted with a view to removing thymol blue (TB) dye from an aqueous solution using a low-cost agricultural biomass, the African native pear (Dacryodes edulis), as the adsorbent. Batch experiments showed that the process was affected by pH, temperature, contact time, and initial thymol blue concentration. Optimum dye adsorption was achieved at pH 12. The data was analyzed using Langmuir and Freundlich isotherm models. The latter isotherm better described this process than the former. The thermodynamic quantities like free energy change (∆G°), enthalpy change (∆H°), and entropy change (∆S°) were also evaluated. It was inferred from the results that the adsorption process was spontaneous, feasible, endothermic in nature, and occured by a physisorption mechanism. These findings indicate that the native peer seed is an efficient biosorbent for thymol blue removal from an aqueous environment.

Hollow fiber gas-diffusion electrodes with tailored crystal facets for tuning syngas production in electrochemical CO2 reduction

Electrochemical reduction of CO2 (CO2RR) in aqueous electrolytes not only relies on advanced gas diffusion electrodes (GDEs) to improve CO2 mass transportation but also efficient electrocatalysts to produce specific products. Herein, to produce syngas (CO and H2 mixture), a facet-orientated zinc nanosheet catalyst was electrodeposited on the Cu hollow fiber GDE via a controllable facile surfactant-assisted method. The introduction of cationic surfactant cetyl trimethyl ammonium bromide (CTAB) could manipulate the nucleation and crystal growth of zinc ions around the GDE during the electrodeposition process, leading to controlled changes in the surface free energy and tuned zinc crystal growth orientation. Consequently, the ZncNS-HF with the largest ratio of Zn (101)/Zn (002), resulted in a high current density of 73.3 mA/cm2 and a high syngas production rate of 1328.6 µmol/h∙cm2 at applied potential −1.3 V (vs. RHE). This comes from the hierarchical structure of HFGDE, which provides sufficient CO2 reaching the catalyst/electrolyte interface, and the well-connected zinc nanosheets contribute to a significant number of active sites for CO2RR. This is the first time to configure flow-through or gas-penetrated HFGDEs with zinc crystal facets controlled nanosheet catalysts for syngas production. This research demonstrates the high potential of nanoengineering catalysts for HFGDEs to achieve high production rates of syngas.

Thermodynamic analysis of anaerobic digestion of Eichornia crassipes (Water Hyacinth) biomass from the Volta River basin of Ghana using fruit waste sludge as inoculum

In order to gain understanding on the utilization of biogas fuel derived from water hyacinth (WH) biomass and render it appealing as a sustainable gaseous fuel, the study reports on its various thermophysical, combustion and thermodynamic parameters. The parameters include, specific enthalpy, internal energy, low heating value, Wobbe number index, changes in Enthalpy, Entropy and Gibbs free energy. The experimental procedure was performed at temperature range of 29±3 °C for 61 days in a BlueSens laboratory-scale anaerobic digestion equipment. It comprised of three fermenter bottles designated as F1, F2 and F3. F1 served as the control and the rest served as the test fermenter bottles. The digestion of water hyacinth and fruit waste sludge (WH+FWS) recorded the highest biogas volumes of 19,798.79 ml in fermenter F2 and 19,168.55 ml in fermenter F3 with methane contents of 53.46 % and 51.85 %, respectively. In comparison, the biogas produced exclusively from the water hyacinth (WH) biomass yielded 12,014.49 ml in F2 and 11,384.25 ml in F3, with methane contents of 46.41 % and 43.31 %, respectively. The best biogas fuel was produced from the digestion of (WH+FWS) in fermenter F2 with an internal energy and enthalpy values of 258.6 KJ/kg. K and 344.9 KJ/kg. K, respectively. A low heating value and Wobbe number of 17.51 MJ/m³ and 17.78 MJ/m³ were determined respectively. The biogas production was simulated using the Gompertz modified kinetic equation in MATLAB and an average specific rate (Kexp) of 371.49 ml/gVS.day was obtained. The rate constant (Kexp) was applied in the linearized form of the Erying-Polanyi equation to determine the changes in Enthalpy Entropy, and Gibbs free energy as -2510.66 J, -304.78 J and 94,219 J, respectively which indicated that, the anaerobic digestion process in this study was only thermodynamically feasible at low temperatures.

Microcalorimetry Techniques for Studying Interactions at Solid–Liquid Interface: A Review

Solid–liquid interfacial phenomena play an essential role in our everyday lives and are often regarded as the outcome of interactions at the solid–liquid interface. However, the intricately intrinsic mechanism underlying interfacial interactions renders in situ simulations and direct measurements challenging. As an effective analytic method for studying solid–liquid interfacial interactions, microcalorimetry can provide the most basic thermodynamic information (including changes in enthalpy, entropy, and Gibbs free energy during solid–liquid binding/separation processes), which is extremely crucial for understanding interaction directionality and limitation. This review is dedicated to highlighting the pivotal role of microcalorimetry in studying solid–liquid immersion and adsorption processes. Specifically, we provide an overview of the commonly employed microcalorimetric methods, including differential scanning calorimetry (DSC), isothermal titration calorimetry (ITC), and immersion microcalorimetry (IM), and delve into the influence factors of enthalpy change, and finally discuss the specific applications of microcalorimetry in studying various solid–liquid binding processes. There remains a vast expanse of thermodynamic information regarding solid–liquid interactions that await exploration via calorimetry.

Effect of alcohol on synergistic interaction between amino sulfonate amphoteric surfactant and zwitterionic cocamidopropyl hydroxysultaine in aqueous solution

Micellization behavior for quasi-binary mixtures of an amino sulfonate amphoteric surfactant, sodium 3-(N-dodecyl ethylenediamino)-2-hydropropyl sulfonate (DES), with a zwitterionic surfactant cocamidopropyl hydroxysultaine (CAHS) both in water-glycerol and in water-glycol and the effect of alcohol were investigated using both the tensiometry and the conductometry. In the framework of regular solution theory and based on the pseudophase separation model, the Rubingh’s model, the Rodenas’ model and the Clint’s model were adopted to successfully estimate the related micellar and thermodynamic parameters. The synergistic interaction between DES and CAHS along with the nonideal mixing are observed in the entire range of mixing. Besides the hydrophobic effect, the compatibility in molecular conformation, the steric hindrance, the feeble electrostatic repulsion, the interaction between dipoles and the formation of hydrogen bond can account for the dependence of the mixed critical micelle concentration and the micellar composition on the content in bulk solution. In comparison with the case of glycerol, the presence of glycol partly disfavors the micellization process. Thermodynamic parameters show that the entropy makes an overwhelming contribution to the spontaneous micellization process, the release of mixing heat promotes the formation of stably mixed micelle, the greater share of entropy in the presence of glycol than in the presence of glycerol displays the disadvantage in the micellization process as well as the dependence of both the free energy change and the share of entropy on the mixing ratio in bulk solution is approximately symmetric with respect to about 0.500.