Thermodynamic Experiments Research Articles

The Interaction of Linear and Network Poly(diallyldimethylammonium chloride) with Water. Thermodynamic Experiment and Modeling

The Interaction of Linear and Network Poly(diallyldimethylammonium chloride) with Water. Thermodynamic Experiment and Modeling

Separation of 1,3,5-trimethylbenzene and 1,2,4-trimethylbenzene by metal-organic framework Co(aip)(bpy)0.5

BackgroundThe separation of trimethylbenzene isomers is one of the most challenging problems in chemical industry because of their similar boiling points and kinetic diameters. The adsorption performance of 1,3,5-trimethylbenzene (1,3,5-TMS) and 1,2,4-trimethylbenzene (1,2,4-TMS) (1,3,5-TMS/1,2,4-TMS = 1:1) on Co(aip)(bpy)0.5 with cobalt-based columnar lamellae were investigated in this paper. MethodsIn this study, we used competitive adsorption experiments, kinetic and thermodynamic experiments, and regeneration experiments to investigate the adsorption amount and relative selectivity of 1,3,5-TMS and 1,2,4-TMS on Co(aip)(bpy)0.5, adsorption mechanism, and regeneration properties of Co(aip)(bpy)0.5. Significant findingsCompetitive adsorption experiments showed that Co(aip)(bpy)0.5 presented the highest relative selectivity α1,2,4-TMS/1,3,5-TMS among the eight MOFs studied. Both pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetic models were used to fit the data, which indicated that the PSO model was more compatible. Thermodynamic data was fitted by Langmuir, Freundlich, and Temkin models, from which the Langmuir model was most suitable. Thermodynamic parameters demonstrated that the adsorption was spontaneous and exothermic. The α1,2,4-TMS/1,3,5-TMS could reach 3.5 at 298.15 K. The crystal structure and adsorption experiments suggested that the separation of 1,3,5-TMS from 1,2,4-TMS on Co(aip)(bpy)0.5 was mainly due to π-π interaction, unsaturated metal ions, and Lewis acid-base interaction. After five adsorption-regeneration cycles, the adsorption amount of 1,3,5-TMS and 1,2,4-TMS decreased by 0.12 % and 0.05 %, respectively, and α1,2,4-TMS/1,3,5-TMS remained above 3.0.

Use of welding powder as a low‐cost adsorbent for waste motor oil removal

AbstractWaste motor oil (WMO), which has no stable form or structure, causes major environmental problems and damage to the ecosystem once it is disposed to the environment. Because of the high toxicity of contents in such effluent, it must be treated before being discharged into the receiving environment. In recent years, the valorization and the use of waste materials to remove toxic pollutants is of great importance to researchers and diverse industries. In this study, the usability of waste welding powder (WWP) as an adsorbent for waste oil removal was investigated. For this purpose, investigating the usability of material, which is generated as industrial waste, in wastewater treatment will lead to the evaluation of waste. The effects of temperature, pH, WWP amount, and initial WMO amount were investigated. According to the adsorption studies, 1 g WWP/L of the processed adsorbent was able to effectively remove 95.05% of WMO (100 mg) at a pH of 2 at 30°C. Stereo microscopy images showed a large amount of oil adsorbed on the WWP surface. The different WWP properties were determined by adsorption isotherm (Harkins–Jura), kinetic (pseudo‐second order), and thermodynamic (ΔG: −5.1 kJ mol–1) experiments. It is thought that WWP, which is a low‐cost and waste material, can be used as a promising adsorbent in WMO removal.

Insights into adsorption performance and mechanism of chitosan-bentonite biocomposites for removal of imazethapyr and imazamox

In the present study, chitosan-bentonite biocomposites were synthesised by ultrasonication, characterized using spectral techniques and assessed for their effectiveness in removing imazethapyr and imazamox from aqueous solution. The response surface methodology based box behnken design was utilized to generate optimum conditions viz. pH (1 to 9), adsorbent dose (0.01 to 1.0 g), contact time (0.5 to 48 h) and temperature (15 to 55 °C) for adsorption of herbicides on biocomposites. Based on model predictions, 60.4 to 91.5 % of imazethapyr and 31.7 to 46.4 % of imazamox was efficiently removed under optimal conditions. Adsorption data exhibited a strong fit to pseudo-second-order kinetic (R2 > 0.987) and Freundlich isotherm (R2 > 0.979). The adsorption capacity ranged from 3.88 to 112 μg1−ng−1mLn and order of adsorption was: low molecular weight chitosan-bentonite> medium molecular weight chitosan-bentonite> high molecular weight chitosan-bentonite> bentonite. Thermodynamic experiments suggested a spontaneous, exothermic process, reducing the system randomness during adsorption. Desorption experiments revealed successful desorption ranging from 91.5 to 97.0 % using 0.1 M NaOH. The adsorption mechanism was dominated by synergistic electrostatic interactions and hydrogen bonding. These results collectively indicated the potential environmental remediation application of chitosan-bentonite biocomposites to adsorb imazethapyr and imazamox from wastewaters.

Influence of Blending High-Calcium Additive on Environmental Safety of B, F, and Se: A Case Study from Thermodynamic Calculation

Coal remains an important fuel for use in thermal power plants. However, coal-burning power plants produce large amounts of CFA, which contains TEs such as B, F, and Se, which are leached upon contact with water and act as potential polluters of aquifer systems and soil. To study the transformation of TEs, a thermodynamic calculation (FactSage 7.2) was used. Paper sludge ash was used as a calcium compound additive. The influence of blending a high-calcium additive on the environmental safety of TEs was investigated based on the effect of the mass addition ratio of PS ash. This study’s results confirmed that the leaching processes of TEs, namely (CaO)2(Al2O3), CaF2, Ca10(PO4)F2, and CaSeO4(H2O)2, were caused by the formation of B, F, and Se compounds during the leaching process. Thus, it is clear that calcium has the greatest influence on the transformation of TEs due to their reaction, which, in turn, minimizes the effects of the TEs’ release into the environment. The concentrations of TEs from the sample and addition of PS ash decreased slightly, indicating that the inhibition of TEs was enabled through the addition of PS ash. Although the PS ash YB had the highest calcium content, the PS ash YC gave the best results during the B and Se inhibition processes. The experimental observation was also evaluated for comparison. For the analysis of TEs’ leaching ratios using the thermodynamic calculation and experiment, the experimental results were lower than those initially predicted. These results will help us to choose the best available control technology to minimize the effects of TEs released into the environment.

Fabrication of cellulose nanocrystals/carboxymethyl cellulose/zeolite membranes for methylene blue dye removal: understanding factors, adsorption kinetics, and thermodynamic isotherms.

This study introduces environmentally-friendly nanocellulose-based membranes for AZO dye (methylene blue, MB) removal from wastewater. These membranes, made of cellulose nanocrystals (CNCs), carboxymethyl cellulose (CMC), zeolite, and citric acid, aim to offer eco-friendly water treatment solutions. CNCs, obtained from sugarcane bagasse, act as the foundational material for the membranes. The study aims to investigate both the composition of the membranes (CMC/CNC/zeolite/citric acid) and the critical adsorption factors (initial MB concentration, contact time, temperature, and pH) that impact the removal of the dye. After systematic experimentation, the optimal membrane composition is identified as 60% CNC, 15% CMC, 20% zeolites, and 5% citric acid. This composition achieved a 79.9% dye removal efficiency and a 38.3mg/g adsorption capacity at pH 7. The optimized membrane exhibited enhanced MB dye removal under specific conditions, including a 50mg adsorbent mass, 50ppm dye concentration, 50mL solution volume, 120-min contact time, and a temperature of 25°C. Increasing pH from neutral to alkaline enhances MB dye removal efficiency from 79.9% to 94.5%, with the adsorption capacity rising from 38.3mg/g to 76.5mg/g. The study extended to study the MB adsorption mechanisms, revealing the chemisorption of MB dye with pseudo-second-order kinetics. Chemical thermodynamic experiments determine the Freundlich isotherm as the apt model for MB dye adsorption on the membrane surface. In conclusion, this study successfully develops nanocellulose-based membranes for efficient AZO dye removal, contributing to sustainable water treatment technologies and environmental preservation efforts.

Thermodynamic and kinetic modeling and experiment on plasma ignition of pulverized high-ash coal

Solid fuels are relatively inexpensive and widely available, making them an attractive option for energy producers. However, they are currently inefficient in converting heat energy into electricity, and new technological advances are needed to make them more efficient. Plasma ignition and stabilization of pulverized coal flame provides a cost-effective and sustainable approach to boiler start-up and combustion stabilization, avoiding the traditionally used fuel oil or gas. This technology consists of heating the air-coal mixture with electric arc plasma to the temperature of coal devolatilization and partial gasification of the coke residue. Thus, a highly reactive two-component fuel, consisting of combustible gas and coke residue, is obtained from the original coal. In this paper, a comprehensive thermodynamic and kinetic analysis was carried out. A thermodynamic analysis was carried out to study the optimal parameters of plasma ignition and stabilization of combustion of a pulverized fuel flame. Kinetic modeling of the process of plasma ignition and stabilization of combustion of pulverized fuel made it possible to obtain changes in temperatures, velocities and concentrations of high-temperature two-component fuel components along the length of the plasma-fuel system. In experiments on plasma ignition of thermal coal, a stable coal-dust flame was obtained, and its temperature, composition and degree of carbon gasification were determined. Comparison of experimental and calculated data showed satisfactory agreement.

Methylene blue dye adsorption on Ghana’s activated clay from Teleku Bukazo

In this work, a clay sample from Teleku Bukazo in the Western Region of Ghana was activated by an acid activation process and the material used for adsorbing methylene blue from wastewater. Zeta potential, scanning electron microscopy, X-ray diffraction analysis, and Fourier transform infrared spectroscopy, analysis were used to characterize the material. To ascertain the impact of temperature, pH, contact time, starting concentration, and adsorbent dosage on the adsorbent, kinetic and thermodynamic experiments were conducted. The optimal dosage required for the removal of MB was 0.1 g in 50 mg/L for 80 min at a pH of 9. The maximum adsorption capacity and removal efficacy were found to be 35 mg/g and 98%, respectively. With an R2 value of 0.9992, the adsorption data most closely matched the Freundlich isotherm. The nature of the adsorption process is pseudo-second-order as confirmed by the correlation (R2 = 0.9982). A spontaneous adsorption process is shown by the negative change in Gibbs free energy at all temperatures (ΔG0 = −1.83 KJ/mol to −1.92 KJ/mol). The decrease in enthalpy change (ΔH0 = −1.08 KJ/mol) indicates an exothermic process. Statistical analyses, including ANOVA in Microsoft Excel, were employed to assess the impact of various parameters such as time, pH, concentration, dosage, and temperature on adsorption. Notably, all tested parameters exhibited statistically significant effects on dye removal (p < 0.05), emphasizing their substantial influence on the adsorption process.

Optimization of pyroprocessing of zinc sulfide ore to produce ferroalloy and zinc

The article presents the results of thermodynamic analysis and experiments on the electric smelting of Shalkiya ore (5.2% of ZnS, 1.0% of PbS, 50% of SiO2) with the joint producing a silicon-containing ferroalloy and extracting zinc and lead into sublimates. The studies included the thermodynamic modeling using the HSC-6.0 software package and electric smelting in an arc furnace. It was established that the interaction in a ZnS-Fe3O4-2C system under equilibrium conditions is of a stepwise nature with the initial reduction of Fe3O4 to Fe and FeO at 600-1000 °C, then the interaction of ZnS with Fe at 1100-1800 °C with the formation of gaseous zinc, and the interaction of ZnS with FeO with the predominant formation of zinc at temperatures above 1600 °C. The electric smelting a charge containing the Shalkiya ore, coke, magnetite concentrate (85.9% of Fe3O4) and steel shavings allowed us to establish that FeSi45 grade ferrosilicon (41.8-44.6% of Si), with the extraction of 80-85.4% of Si, can be produced in the presence of 24.9-30% of coke with the replacement of magnetite’s iron by steel shavings’ iron from 20.9 to 91.8%. A lower degree of this replacement is associated with intensive development of foaming and a decrease in the extraction of silicon into the alloy. At least 98% of zinc and 96% of lead are extracted into the resulting sublimates containing 29.4% of zinc and 15.1% of lead.

Biosorption of nickel by ground fallen waste coffee plant leaves powder: Equilibrium, kinetics, Thermodynamics and Optimization (RSM)

This study reports the biosorption of nickel using powdered fallen coffee leaves. BET, SEM, FTIR, and XRD characterize the biosorbents. We go over the findings from thermodynamic, kinetic, and equilibrium biosorption experiments. Here are some of the factors that were studied: agitation duration (t), biosorbent size, pH of the aqueous solution (ranging from 1 to 8), initial nickel concentration (C0), pH (ranging from 5 to 150), temperature (ranging from 283 to 323), and so on. Coffee leaf powder is best when the pH is 4. This biosorbent pair works best when dosed at 18 g/L for nickel biosorption. Nitrogen absorption is 4.219 mg/g when coffee leaf powder is used. For nickel biosorption, CCD has optimized four parameters. The data on nickel biosorption are tightly matched to the biosorbent model of pseudo-second-order. The negative sign of the free energy change (ΔG) for coffee leaf powder (-1546 J/mol) reflects both the practicality and spontaneous nature of the biosorbent-material. Powdered coffee leaves are predicted to undergo enthalpy changes of 62.99 J/mol K and entropy changes of 51.08 J/mol K. When the value of ΔS is positive, it indicates that the randomness is increasing, and when the value of enthalpy change is positive, it indicates that the process is endothermic.

Preparation of Titanium Carbide by Carburisation of Titanium Dioxide

Titanium carbide has attracted widespread attention due to its excellent properties. This study investigates the process of carbon thermally reducing TiO2 to prepare TiC through a combination of thermodynamic analysis and experiments. The effects of temperature, TiO2/C molar ratio, and time on the phase transformation and morphology evolution of the products are investigated. The synthesis of titanium carbide involves the main reduction path of TiO2–Magnéli–Ti3O5–Ti2O3–TiCxO1−x. With the increase in reaction temperature and TiC content, the microstructure transitions from a smooth disc-like structure to a loose and porous layered structure, while the particle size decreases significantly. The carburisation rate of the reduced product is more affected by temperature, according to chemical analysis. The carburisation rate increased from 18.37% to 36.09% for 2 h–10 h of holding time at 1400 °C, and from 51.43% to 77.57% for 2 h–10 h of holding time at 1500 °C. The quantification of the carburisation rate provides a valuable reference for the preparation of titanium carbide by TiO2.

Exploration and Practice of Teaching Reform in Chemical Thermodynamics Theory and Experiments Based on the “Dual Carbon” Background

Exploration and Practice of Teaching Reform in Chemical Thermodynamics Theory and Experiments Based on the “Dual Carbon” Background

Three water-soluble copper(II) N-heterocyclic carbene complexes: toward copper-catalyzed ketone reduction under sustainable conditions.

A series of tridentate copper(II) N-heterocyclic carbene (NHC) complexes with imidazole, benzimidazole, and 5,6-dimethylbenzimidazole azole rings were synthesized and comprehensively characterized via X-ray crystallography, ESI-MS, cyclic voltammetry, and UV-Vis and EPR spectroscopic studies. These complexes were then utilized for the optimization of ketone reduction under sustainable conditions using 2-acetylpyridine and phenylsilane. The relationships between product formation, temperature, reaction time, and catalyst loading for the hydrogenation reactions are covered in detail. Reduction of eighteen different aliphatic, cyclic, and aromatic ketones were demonstrated, which were compatible to produce the corresponding products in moderate to good yields. These systems were used to develop related DNA-hybrid catalytic systems, but only supported weak enantioselectivity. Further thermodynamic experiments showed Cu-NHC complexes did not demonstrate specific binding to DNA, which is consistent with their limited selectivity.

Exploring the carbon-chain structure-activity relationship of CO2 and ketone-based absorbents

With regard to the physical absorbents for CO2 removal, the alteration of carbon-chain structure may benefit the CO2 absorption performance. However, the relationship between the carbon-chain structure of ketones absorbents and their CO2 absorption capacity has rarely been studied, and the related mechanism is unclear. In this study, theoretical calculations and thermodynamic experiments were carried out to explore the effects of the carbon-chain length and isomerism of ketones on their CO2 absorption performance. The density functional theory (DFT) simulations show that the F-∥ configuration is more stable than the others for the CO2+ketone complex in most cases. The followings are obtained according to the experimental results, which are pretty consistent with DFT calculations. The dissolution of CO2 in the ketone is a typical physical process. As the number of carbon atom increases, the CO2 absorption capacity of straight-chain ketones increases. Straight-chain ketones exhibit higher CO2 absorption capacity than branched-chain ones. The effect of increasing carbon-chain length and isomerism on CO2 absorption capacity are both stronger for the ketones with fewer carbon atoms; the influence mechanism can be attributed to different degrees of weak hydrogen-bond interaction between CO2 and ketone molecules, suggested by the DFT simulation results. The above conclusions are beneficial for the development of potential CO2 capture absorbents. In addition, the industrial application feasibility of surveyed ketone absorbents is also discussed.

Green-engineered clay- and carbon-based composite materials for the adsorption of benzene from air

Benzene is a carcinogenic volatile organic compound (VOC) that is ubiquitously detected in enclosed spaces due to emissions from cooking activities, building materials, and cleaning products. To remove benzene and other VOCs from indoor air and protect public health, traditional fabric filters have been modified to contain activated carbons to enhance the filtration efficacy. In this study, composites derived from natural clay minerals and activated carbon were individually green-engineered with chlorophylls and were attached to the surface of filter materials. These systems were assessed for their adsorption of benzene from air using in vitro and in silico methods. Isothermal, thermodynamic, and kinetic experiments indicated that all green-engineered composites had improved binding profiles for benzene, as demonstrated by increased binding affinities (Kf ≥ 900 vs 472) and lower values of Gibbs free energy (ΔG = −16.8 vs −15.2) compared to activated carbon. Adsorption of benzene to all composites was achieved quickly (< 30 min), and the green-engineered composites also showed low levels of desorption (≤ 25%). While free chlorophyll is known to be photosensitive, chlorophylls in the green-engineered composites showed photostability and maintained high binding rates (≥ 70%). Additionally, the in silico simulations demonstrated the significant contribution of chlorophyll for the overall binding of benzene in clay systems and that chlorophyll could contribute to benzene binding in the carbon-based systems. Together, these studies indicated that novel, green-engineered composite materials can be effective filter sorbents to enhance the removal of benzene from air.

Hydrophobic deep eutectic solvents as the green media for highly efficient extraction of Cr(VI) over a broad pH range and low oil-water ratio

The occurrence of Cr(VI) ions in aquatic ecosystems poses serious public health risks, making the development of effective removal technology for Cr(VI) ions urgent. This study presents a green and effective method for extracting Cr(VI) ions using hydrophobic deep eutectic solvents (HDESs) composed of tetran-octyl ammonium bromide and carboxylic acids. The results show that the extraction efficiency of [N8888][Br]-C6OOH(1:2) for Cr(VI) is as high as 98.2 % for high concentration of Cr(VI) (500 mg⋅g−1) with a low oil–water ratio of 1:66. Surprisingly, these HDESs demonstrate remarkable efficacy in extracting Cr(VI) ions over a broad pH range and at a low oil–water ratio, even in the presence of multiple competing ions. A serious of kinetic, thermodynamic, and spectroscopic experiments suggested that the extraction mechanism of Cr(VI) ions is a synergistic dissolution diffusion and ion exchange. As a proof of concept, we have successfully demonstrated the application of prepared HDESs for extracting trace amounts of Cr(VI) ions from H3PO4 solutions with varying mass fractions, and the extraction process resulted in a Cr(VI) removal rate that achieved 99.7 %. Furthermore, the extraction performance HDESs for Cr(VI) ions remained nearly unchanged after eight cycles of continuous extraction and regeneration. Impressively, a precipitation method was also employed to convert the isolated Cr(VI) ions into valuable BaCrO4. The research findings provide valuable insights for the development of highly efficient Cr(VI) extractants.

New and effective cassava bagasse-modified biochar to adsorb Food Red 17 and Acid Blue 9 dyes in a binary mixture.

A promissory technic for reducing environmental contaminants is the production of biochar from waste reuse and its application for water treatment. This study developed biochar (CWb) and NH4Cl-modified biochar (MCWb) using cassava residues as precursors. CWb and MCWb were characterized and evaluated in removing dyes (Acid Blue 9 and Food Red 17) in a binary system. The adsorbent demonstrated high adsorption capacity at all pH levels studied, showing its versatility regarding this process parameter. The equilibrium of all adsorption experiments was reached in 30 min. The adsorption process conformed to pseudo-first-order kinetics and extended Langmuir isotherm model. The thermodynamic adsorption experiments demonstrated that the adsorption process is physisorption, exhibiting exothermic and spontaneous characteristics. MCWb exhibited highly efficient and selective adsorption behavior towards the anionic dyes, indicating maximum adsorption capacity of 131 and 150 mg g-1 for Food Red 17 and Acid Blue 9, respectively. Besides, MCWb could be reused nine times, maintaining its original adsorption capacity. This study demonstrated an excellent adsorption capability of biochars in removing dyes. In addition, it indicated the recycling of wastes as a precursor of bio composts, a strategy for utilization in water treatment with binary systems. It showed the feasibility of the reuse capacity that indicated that the adsorbent may have many potential applications.

Preparation of novel polyvinyl alcohol–carbon nanotubes containing imidazolyl ionic liquid/chitosan hydrogel for highly efficient uranium extraction from seawater

A novel polyvinyl alcohol–carbon nanotube containing an imidazolyl ionic liquid/chitosan composite hydrogel (termed CBCS) was prepared for highly selective uranium adsorption from seawater. The results show that CBCS has good adsorption properties for uranium within the pH range of 5.0–8.0. Kinetics and thermodynamics experiments show that the theoretical maximum adsorption capacity of CBCS to U(VI) is 496.049 mg/g (288 K, pH = 6.0), indicating a spontaneous exothermic reaction. Mechanism analysis shows that the hydroxyl group, amino group, and CN bond on the surface of CBCS directly participate in uranium adsorption and that the dense pores on the surface of CBCS play an important role in uranium adsorption. The competitive adsorption experiment shows that CBCS has excellent uranium adsorption selectivity. In addition, CBCS exhibits good reusability. After five adsorption–desorption cycles, the uranium adsorption rate of CBCS can still reach >98 %. Hence, CBCS has excellent potential for uranium extraction from seawater.

Dispersive solid phase extraction based on cross-linked hydroxypropyl β-cyclodextrin polymers for simultaneous enantiomeric determination of three chiral triazole fungicides in water.

Anefficient method is presentedfor simultaneous enantioselective determination of three chiral triazole fungicides (namely paclobutrazol, hexaconazole, and diniconazole) in water samples by DSPE-HPLC-UV. The perfect chiral separation of the enantiomers was achieved on a Chiralpak IH column within 15min. In order to adsorb and enrich the analytes from water matrices, a cross-linked hydroxypropyl β-cyclodextrin polymer was synthesized. The prepared material exhibited good adsorption capacity, which was assessed by adsorption kinetic and adsorption thermodynamic experiments. One-variable-at-a-time and the response surface methodology were used to optimize the extraction parameters. Under the optimum sample preparation conditions, good linearity (2.0 ~ 800µg L-1, R2 ≥ 0.9978), detection limits (0.6 to 1.0µg L-1), quantitation limits (2.0 to 3.2µg L-1), recoveries (86.7 ~ 105.8%), and the relative standard deviation (intra-day RSD ≤ 3.7%, inter-day RSD ≤ 5.1%) were obtained, satisfying the requirements of pesticides residues determination. These results demonstrated that the proposed method was applicable for routine determination of chiral triazole fungicide residues in water samples.

Iopamidol Abatement from Waters: A Rigorous Approach to Determine Physicochemical Parameters Needed to Scale Up from Batch to Continuous Operation.

The abatement of iopamidol (IPM), an X-ray iodinated contrast agent, in aqueous solution using powdered activated carbon (PAC) as a sorbent was investigated in the present work. The material was characterized by various analytical techniques such as thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller analysis, dynamic light scattering, and zeta potential measurements. Both thermodynamic and kinetic experiments were conducted in a batch apparatus, and the effects of the initial concentration of IPM, the temperature, and the adsorbent bulk density on the adsorption kinetics were investigated. The adsorption isotherms were interpreted well using the Langmuir model. Moreover, it was demonstrated that IPM adsorption on PAC is spontaneous and exothermic (ΔH0 = -27 kJ mol-1). The adsorption kinetic data were described using a dynamic intraparticle model for fluid-solid adsorption kinetics (ADIM) allowing determination of a surface activation energy Es = 6 ± 1 kJ mol-1. Comparing the experimental results and the model predictions, a good model fit was obtained.