Activation Entropy Change Research Articles

Synthesis, characterization and thermal behavior of antibacterial and antifungal active zinc complexes of bis (3(4-dimethylaminophenyl)-allylidene-1,2-diaminoethane

In this work, synthesis of a new series of zinc halide/pseudohalide complexes of a bidentate Schiff base ligand entitled as bis (3-(4-dimethylaminophenyl)-allylidene)-1,2-diaminoethane(L) is described. The ligand and its zinc complexes were characterized by various techniques such as elemental analysis, FT-IR, UV–visible, 1H and 13C NMR spectra, cyclic voltammetry, and conductometry. Accordingly ZnLX2 (X=Cl−, Br−, I−, SCN− and N3−) was suggested as molecular formula of the complexes. Redox behaviors of ligand and its zinc complexes were investigated by cyclic voltammetry method. Furthermore, the ligand and its zinc halide/pseudohalide complexes were tested for their in vitro antibacterial activities against two gram positive bacteria (Staphylococcus aureus and Bacillus subtilis) and two gram negative bacteria (Escherichia coli and Pseudomonas aeruginosa). Also in vitro antifungal activities of them against Candida albicans and Aspergillus niger were investigated. The results indicated that all compounds are antibacterial and antifungal active. Thermal behaviors of ligand and its zinc complexes were studied from room temperature to 1100°C under argon atmosphere. It was found that the ligand and zinc iodide are decomposed completely via three and four steps respectively while other zinc complexes leave out the metal or organometallic compounds as final residuals after 3–4 decomposition steps at above temperature range. Moreover evaluation of some thermo-kinetic parameters such as activation energy (∆E⁎), enthalpy (∆H⁎), entropy (∆S⁎) and Gibbs free energy change (∆G⁎) of the thermal decomposition steps were performed based on the Coats–Redfern relation.

Ion-exchange and humidity sensing properties of poly-o-anisidine Sn(IV) arsenophosphate nano-composite cation-exchanger

In order to develop a new kind of humidity sensing material, the poly-o-anisidine nano-composite containing Sn(IV) arsenophosphate cation-exchanger was synthesized using by sol–gel method. Cation-exchange behaviors were studied in order to get the material suitable for its application as ion-exchanger. By studying ion exchange kinetics some of the physical parameters like self diffusion coefficient (D°), energy of activation (Ea) and standard entropy change (ΔS°) have been evaluated under conditions favoring a particle diffusion controlled mechanism. The humidity sensing response (adsorption) and recovery (desorption) time of the nano-composite was examined at room temperature (25°C). It was observed that the electrical conductivity varied according to low humidity to high humidity increased from 10−4 to 10−1Scm−1 when pressed pellets made from the synthetic nano-composite was exposed to the range of humidity level from 20% to 90%. The results indicated that in comparison with pristine poly-o-anisidine not only the morphology of nanocomposite was entirely changed, but its thermal stability as well as water vapour sensitivity was also improved appreciably by adding Sn(IV) arsenophosphate cation exchanger when incorporated in poly-o-anisidine.

PtII-Catalyzed Ethylene Hydrophenylation: Influence of Dipyridyl Chelate Ring Size on Catalyst Activity and Longevity

Expansion of the dipyridyl ligand from a five- to six-membered chelate for PtII-catalyzed ethylene hydrophenylation provides an enhancement of catalyst activity and longevity. Mechanistic studies of [(dpm)Pt(Ph)(THF)][BAr′4] [dpm = 2,2′-dipyridylmethane, and Ar′ = 3,5-(CF3)2C6H3] attribute the improved catalytic performance at elevated temperatures to a favorable change in entropy of activation with an increase in chelate ring size. The PtII catalyst precursor [(dpm)Pt(Ph)(THF)][BAr′4] is among the most active catalysts for ethylene hydrophenylation by a non-acid-catalyzed mechanism.

Thermoanalytical investigation of terazosin hydrochloride.

Thermal analysis (TGA, DTG and DTA) and differential scanning calorimetry (DSC) have been used to study the thermal behavior of terazosin hydrochloride (TER). Thermogravimetric analysis (TGA/DTG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC) were used to determine the thermal behavior and purity of the used drug. Thermodynamic parameters such as activation energy (E*), enthalpy (∆H*), entropy (∆S*) and Gibbs free energy change of the decomposition (∆G*) were calculated using different kinetic models. The purity of the used drug was determined by differential scanning calorimetry (99.97%) and specialized official method (99.85%) indicating to satisfactory values of the degree of purity. Thermal analysis technique gave satisfactory results to obtain quality control parameters such as melting point (273 ºC), water content (7.49%) and ash content (zero) in comparison to what were obtained using official method: (272 ºC), (8.0%) and (0.02%) for melting point, water content and ash content, respectively. Thermal analysis justifies its application in quality control of pharmaceutical compounds due to its simplicity, sensitivity and low operational costs. DSC data indicated that the degree of purity of terazosin hydrochloride is similar to that found by official method.

Thermal behaviour and thermodegradation kinetics of poly(vinyl chloride) plasticized with polymeric and oligomeric medium-chain-length poly(3-hydroxyalkanoates)

Poly(vinyl chloride) (PVC) is a well-known polymer with low thermal stability. With the aim to improve the physical properties of PVC, biopolyesters were investigated for the plasticizing and thermal effects in PVC. In this study, polymeric medium-chain-length poly(3-hydroxyalkanoates) (mcl-PHA) were produced by Pseudomonas putida PGA1 using renewable carbon substrates and oligomeric mcl-PHA were generated by partial thermal degradation of the polymers. The effects of blending these biopolyesters with PVC were investigated in terms of thermal behaviour and thermodegradation kinetics. The PVC/PHA blends showed a single Tg with lower values than PVC, indicating that mcl-PHA was compatible with PVC. Tg from DSC analysis agreed well with theoretical Tg predicted from Gordon–Taylor equation. The apparent activation energy (Ed) and pre-exponential factor (A) for the thermodegradation of PVC and its blends were determined using Kissinger method. Change in entropy of activation (ΔS) for the thermodegradation was also determined. All PVC/PHA blends had lower Ed, A and ΔS than PVC. Higher reduction of Ed, A and ΔS was observed when the proportion of PHA was increased in the blend; and when oligomeric PHA was used as the plasticizer instead of polymeric PHA. The dependence of Ed on the extent of conversion (α) for the thermodegradation process of PVC and PVC/PHA was determined by Flynn–Wall–Ozawa method and results showed that Ed is an increasing function of α. This indicated that the thermal decomposition of PVC and its blends display complex reaction mechanism(s).

Thermodynamic Analysis of the Interaction of Factor VIII with von Willebrand Factor

Factor VIII (FVIII) is a glycoprotein that plays an important role in the intrinsic pathway of coagulation. In circulation, FVIII is protected upon binding to von Willebrand factor (VWF), a chaperone molecule that regulates its half-life, distribution, and activity. Despite the biological significance of this interaction, its molecular mechanisms are not fully characterized. We determined the equilibrium and activation thermodynamics of the interaction between FVIII and VWF. The equilibrium affinity determined by surface plasmon resonance was temperature-dependent with a value of 0.8 nM at 35 °C. The FVIII-VWF interaction was characterized by very fast association (8.56 × 10(6) M(-1) s(-1)) and fast dissociation (6.89 × 10(-3) s(-1)) rates. Both the equilibrium association and association rate constants, but not the dissociation rate constant, were dependent on temperature. Binding of FVIII to VWF was characterized by favorable changes in the equilibrium and activation entropy (TΔS° = 89.4 kJ/mol, and -TΔS(++) = -8.9 kJ/mol) and unfavorable changes in the equilibrium and activation enthalpy (ΔH° = 39.1 kJ/mol, and ΔH(++) = 44.1 kJ/mol), yielding a negative change in the equilibrium Gibbs energy. Binding of FVIII to VWF in solid-phase assays demonstrated a high sensitivity to acidic pH and a sensitivity to ionic strength. Our data indicate that the interaction between FVIII and VWF is mediated mainly by electrostatic forces, and that it is not accompanied by entropic constraints, suggesting the absence of conformational adaptation but the presence of rigid "pre-optimized" binding surfaces.

Adsorption and Inhibitive Effects of 2-Thiobenzylbenzimidazole (TBBI) at Aluminium Alloy AA3003/ 1M Hydrochloric Acid Interface

The interfacial behavior of 2-Thiobenzylbenzimidazole (TBBI) between aluminium alloy AA 3003 and 1M hydrochloric acid solution was investigated by mass loss technique. Mass loss is concentration and temperature dependent. The influence of temperature has been studied in the absence and in presence of TBBI in the hydrochloric solution in the range 35-55oC. Adsorption isotherms models including Langmuir, Temkin, Freundlich and El-Awady were tested. It was found that the inhibitor adsorbs on the metal according to the modified Langmuir adsorption isotherm. Some thermodynamic adsorption parameters (�G ° �H ° ,�S ° ) as well as activation parameters including apparent activation energy (Ea), change in activation enthalpy (� � ) and change in activation entropy (� � ) have been calculated and analyzed. Furthermore the DubininRaduskevitch model has been used to distinguish between chemisorption and physisorption. The properties most relevant to the potential action as a corrosion inhibitor of TBBI have been calculated: highest occupied molecular orbital energy (EHOMO), lowest unoccupied molecular orbital energy (ELUMO), energy gap (ΔE), dipole moment (µ) and charges on the adsorption centers (S, N) and C atoms in benzimidazole and benzyl rings. These calculations were performed using the Gaussian Research Article

Viscometric study of lysozyme solution with sugar and urea at various temperatures

This paper presents the results of viscosity measurement of three ternary systems i.e.1-d (−) Glucose+lysozyme+water2-Maltose+lysozyme+water3-Urea+lysozyme+waterat temperatures (293.15, 303.15, 313.13 and 323.15K) at various concentrations of glucose, maltose and urea. Change in entropy (ΔH), enthalpy (ΔS) and free energy of activation (ΔG) have also been evaluated for these systems. Value of B-coefficient of d (−) glucose, maltose and urea has also been calculated from viscosity data in aqueous lysozyme solution. Viscosity B-coefficients of glucose and maltose in aqueous lysozyme solution are positive while that of the urea–lysozyme water system it is negative due to the structure breaking effect of urea. The values of entropy of activation are negative due to attainment of transition state for viscous flow, which is accompanied by bond formation and increase in order.

Effects of fluazinam on soil sucrase activitiy and respiration

使用农药控制作物害虫和疾病可提高农业生产力, 然而农药的使用对土壤造成的污染已成为巨大且日益严重的问题。重复、广泛使用的农药进入土壤影响土壤生物、生物代谢及其生物活性, 已成为农业生态环境重要的研究内容。为了更好地了解氟啶胺对土壤微生物活性和土壤质量等潜在环境危险, 采用实验室模拟的方法研究了氟啶胺农药残留动态, 以及氟啶胺对土壤呼吸强度、蔗糖酶活性及其动力学和热力学特征参数的影响。结果表明: 高剂量(100 mg·kg^-1)氟啶胺在土壤的降解速率常数最大, 氟啶胺在土壤中的半衰期范围为0.38~0.59 d。高剂量(50 mg·kg^-1、100 mg·kg^-1 和1 000 mg·kg^-1)氟啶胺对土壤蔗糖酶表现出不同程度的抑制作用; 低剂量(1 mg·kg^-1、5 mg·kg^-1)处理表现为抑制-激活-抑制作用, 且波动范围较大; 10 mg·kg^-1 氟啶胺对土壤蔗糖酶前期表现为抑制、后期表现为激活作用, 波动范围较大。不同浓度氟啶胺胁迫下蔗糖酶促反应的Michaelis 常数(<em>K_m</em>)和最大反应速率(<em>V</em>_max)发生改变, 但变化不大。土壤中氟啶胺浓度为1 mg·kg^-1 时蔗糖酶所需的活化能(<em>E_a</em>)比CK 高, 其他浓度都低于CK; 5 mg·kg^-1、10 mg·kg^-1、50 mg·kg^-1、100 mg·kg^-1 和1 000 mg·kg^-1 所需的活化焓变(Δ<em>H</em>)随氟啶胺的浓度降低而变小; 在相同温度下蔗糖酶的活化熵变(Δ<em>S</em>)表现为: 1 mg·kg^-1<CK;活化自由能(Δ<em>G</em>)变化差异较小; 320~330 K (开氏温度)时最大速度常数(<em>Q</em>₁₀)最大, 而290~300 K 时<em>Q</em>₁₀ 较小。低剂量氟啶胺对土壤微生物呼吸作用的影响表现为随时间变化呈现抑制-激活趋势, 高低剂量表现为抑制作用。土壤微生物的呼吸活性因氟啶胺的加入而产生波动。本研究结果有助于进一步分析研究受农药污染土壤的质量和酶活之间的相关性。

Rheology and processability of polyamide66 filled with different‐sized and size‐distributed calcium carbonate

AbstractTwo‐sized calcium carbonates (CaCO3) were blended and filled into polyamide66 (PA66). The shear viscosity of PA66/CaCO3 composites was measured with a capillary extrusion rheometer. The results showed that the shear viscosity of the efficient size distribution samples (PA66 was filled with 600/2500 mesh CaCO3 blending) obviously decreased compared with that of the single‐size distribution samples (PA66 was filled with 600 or 2500 mesh CaCO3). The shear viscosity of PA66/CaCO3 composites at different temperatures was also studied. The results showed that the flow activation energy and flow activation entropy of the efficient size distribution samples obviously increased compared with those of the single‐size distribution samples. The change in flow activation entropy was used to explain the experimental results of shear viscosity. The processability of PA66/CaCO3 composites was evaluated with a HAAKE torque rheometer. The results showed that the processability of the efficient size distribution samples was obviously improved and the best efficiency of processability improvement appeared in the 30 wt% CaCO3 content. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers

Effects of CuCl2·6H2O and ZnCl2·6H2O on the viscosity of aqueous ethanol mixtures

The effects of CuCl2 and ZnCl2 on the viscosity in aqueous ethanol mixtures (10%–50% v/v) were studied in the concentration range 1.0×10−2–8.0×10−2 mol·dm−3 at different temperatures. It was found that the viscosities increased with an increase in the concentration of the salts and percent composition of ethanol content, whereas it decreased with an increase in temperature. Ion-ion and ion-solvent interactions are determined with the help of A- and B-coefficients of Jones-Dole equation. The values of A- and B-coefficients are irregular and increase with a rise in temperature and also with an increase in ethanol contents for both salts. Negative values of B-coefficients show that ion solvent interactions is comparatively small and suggest that CuCl2 and ZnCl2 behave as structure breakers in aqueous ethanol mixtures. Thermodynamic parameters like the energy of activation (Eη) and change in entropy of activation (ΔS*) were also evaluated which confirm the structure breaker behavior of salts in aqueous ethanol mixtures.

Thermodynamic analysis of the kinetics reactions of the production of FAME and FAEE using Novozyme 435 as catalyst

Biodiesel is a biofuel expected to become a substitute for petroleum diesel. One of the most promising technologies for production of biodiesel is enzymatic catalysis. However, low catalytic performance of most of the enzymes employed makes such processes expensive and time-consuming. This work describes a kinetic study of the enzymatic production of biodiesel at different temperatures using either methanolysis or ethanolysis, using immobilized lipase from Candida antarctica (Novozym 435) as catalyst. Reactions kinetics were followed by GC, and data were used to perform thermodynamic analysis of the transition state using Arrhenius equation. We found that methanolysis is faster than ethanolysis at temperatures above 13°C. Thermodynamic analysis of the kinetics of reactions showed that methanol is favored as acyl acceptor due to the positive activation entropy change of reaction. These data may be useful in the development of new enzymes and new processes for enzymatic production of biodiesel.

Spectrophotometric Study on Kinetics of Solvatochromism of Methyl Violet in Aqueous Methanol

AbstractThe kinetics of the reaction of methyl violet with iodide in aqueous methanol system was studied by spectrophotometric method. The rate of reaction of methyl violet in different alcoholic composition in presence of potassium iodide was observed at pH 4 and 6 at various temperatures (298–318 K). Solvatochromic effect was studied in different percentages of methanol (0–50%). Bathochromic shift was observed with the decrease in polarity of solvent. The color change was attributed to molecule's structure, the delocalization of unit electrical charge causes deepening of color and decrease of delocalization causes fading of color due to reduction of dye. Increase in the rate of reaction was observed with increase in alcoholic content and also affected by potassium iodide salt and increased with increase in concentration of potassium iodide. Energy of activation (Ea) and transition energy (ET) were calculated with the help of kinetic data. Thermodynamic parameters such as enthalpy change of activation (ΔH*), Gibbs free energy change of activation (ΔG*) and entropy change of activation (ΔS*) were evaluated as a function of concentration of solvent and salt.

KINETICS AND MECHANISM OF OXIDATION OF L-ASCORBIC ACID BY CHROMIUM (VI)

The kinetics of oxidation of L-ascorbic acid by potassium chromate was studied as a function of pH, L-ascorbic acid concentration and temperature using the spectrophotometric technique. The rate of reaction is first order with respect to the concentration of each reactant and increases as [H+] increases. The kinetic data indicate involvement of the monoprotonated ascorbate species (HA-) in the redox process. A mechanism involving the formation of chromium (VI)- ascorbate intermediate is a rate-determining step followed by a redox step was suggested. The activation enthalpy and activation entropy changes for the reaction have been calculated to be ΔH*= 69 kJmol-1 and ΔS*= -209 JK-1 mol-1, respectively.

Crystallinity effect on the gas transport in semicrystalline coextruded films based on linear low density polyethylene

AbstractThis article describes the diffusion and permeability of oxygen, carbon dioxide, methane, ethane, ethylene, propane, and propylene in 1‐octene based polyethylene of densities 0.94, 0.92, 0.904, and 0.87. The isotherms obtained in the time‐lag experimental device display a diffusion coefficient and permeability behavior similar to that of glassy polymers. We apply the dual model to semicrystalline polymers assuming that Henry's sites are related to the amorphous phase, which decreases when the crystallinity percentage increases. Whereas the interphase of the polymeric matrix and the crystalline phase prevails and acts as Langmuir sites. Their effect is to increase both, the tortuosity of diffusion trajectories and the chain immobilization. We now explain this effect using thermodynamic considerations. In fact, the tortuosity is related to the change in activation entropy, and the chain immobilization to the cohesive energy of the polymeric matrix. In those terms, the diffusion coefficient does not follow the same crystalline percentage dependence than the solubility. According to the previous findings, the solubility changes in proportion to amorphous percentages. Instead, diffusion coefficient has exponential dependence. Furthermore, we show that the permeability changes as a consequence of the modification of diffusion and solubility, according to the product of both quantities. Comparison with previous publication has been included. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 634–642, 2010

Signatures of activation parameters reveal substrate-dependent rate determining steps in polysaccharide turnover by a family 18 chitinase

Glycoside hydrolases play an important role in the degradation of biomass such as cellulose and chitin. Many of these enzymes act by a processive mechanism, which is generally considered favorable because it improves substrate-accessiblity. Recently we showed that this only applies to insoluble substrates. Towards more soluble and accessible substrates, processivity may in fact reduce the catalytic activity. Here, we describe kinetic studies showing how the type of substrate, insoluble or soluble, affects the activation parameters and rate determining steps for catalysis by the processive two-domain chitinase A (ChiA) from Serratia marcescens. The activation parameters show a large entropic activation barrier, indicative of a bimolecular (associative) rate determining step, for the degradation of insoluble crystalline β-chitin. For the water-soluble polymeric chitin-derivative chitosan, the rate determining step is associated with product-displacement and release. Furthermore, the degree of processivity is reflected in the activation parameters for chitosan hydrolysis; increase in processivity results in increase in activation enthalpy change and decrease in activation entropy change.

Characterization and Evaluation of Thermodynamic Parameters for Egyptian Heap Fired Rice Straw Ash (RSA)

The composition of the studied ash was confirmed by elemental analysis, IR, XRD spectra, and thermal data (TG & DTA). These analyses were used to determine thermodynamic parameters such as the activation energy (ΔEa), enthalpy change (ΔH*), entropy change (ΔS*) and free energy change (ΔG*) related to the thermal decomposition process were calculated. Analytical reactions were also used to evaluate the composition of the ash.

Dielectric relaxations in chitosan solution with varying concentration and temperature: analysis coupled with a scaling approach and thermodynamical functions

The dielectric properties of chitosan in an aqueous solution with no added salts have been measured as a function of concentration and temperature in the frequency range from 40 Hz to 110 MHz, respectively. After reducing the contribution of the electrode polarization effects, the dielectric spectra of chitosan semidilute solutions show two relaxations at 100 kHz and MHz, respectively. The observed two dielectric relaxations have been strictly analyzed using the Cole-Cole function and the possible relaxation mechanisms were attributed to the fluctuation of condensed counterions and free counterions, respectively. The dependence of the dielectric increment and relaxation time on concentration was interpreted in light of the scaling properties of polyelectrolyte solutions. It was found that the dependence of relaxation time on the Cp follows the expected exponents of the scaling laws, both in the low-frequency and high-frequency cases. The good agreement between experimental results and theoretical analysis suggests that the low- and high-frequency relaxation mechanisms are the fluctuation of condensed counterions and free counterions, respectively. In addition to this, this analysis gives further support to the scaling approach of the dynamic behavior of polyelectrolytes. The temperature dependence of the dielectric spectrum of chitosan solutions showed that the low- and high-frequency dielectric increment generally decreases with the rise of temperature, which is considered to be due to the acceleration of the reorientation motion of the counterions. Moreover, the thermodynamic parameters, such as activation free energy Ea, activation enthalpy change ΔH and activation entropy change ΔS of low- and high-frequency were calculated from the relaxation time, and discussed from the microscopic thermodynamical view.

Ionic studies of sodium alginate isolated from Sargassum terrarium (brown algea) karachi coast with 2,1-electrolyte

Physical and chemical analysis of the polysaccharide isolated from Sargassum Terarrium (brown algae) of Karachi coast showed characteristics of the sodium alginate. Optical rotations and sulphated ash content were found and FTIR spectra showed a sharp and strong absorption band at 1600cm−1 representing carboxylate ion which conforms high uronic acid content of the product. The viscosities of aqueous 0.1% sodium alginate solution were measured in the presence of copper II chloride (CuCl2). The viscosities were found to be increased with the increase in the concentration of electrolyte. Viscosities were also found affected with temperature. ‘A’ and ‘B’ coefficients of Jones–Dole equation were evaluated. The increase in positive values of ‘B’ coefficient with the rise of temperature led to conclusion that given electrolyte in 0.1% aqueous sodium alginate solution behaves as structure maker. Thermodynamic parameters regarding to activated state like energy of activation Eη, change in free energy of activation ΔGη and change of entropy of activation ΔSη were also evaluated. Straight-line plots of log η versus 1/T observed with positive slopes show the effect of temperature on the viscosities of solutions. Energy of activation (Eη) was found to be decreased with the rise of temperature. Change in free energy of activation (ΔGη) was also found to be increased with increase in concentrations of electrolyte and also with rise of temperature. The values of change in entropy of activation (ΔSη) were also calculated. Negative values of ΔSη were found to be increased with increase in concentration of electrolyte and also with rise of temperature.

Kinetics and mechanism of extraction of Cu(II) by CYANEX 302 from nitrate medium and oxidative stripping of Cu(I) using Lewis cell technique

The extraction of Cu(II) from nitrate medium using CYANEX 302 (bis(2,4,4-trimethylpentyl) monothiophosphinic acid) in kerosene under equilibrium conditions showed that copper is first extracted as Cu 2+ followed by reduction of CuA 2 (HA) 2 to Cu + while the CYANEX 302 extractant is correspondingly oxidized. The stripping of Cu(II) from loaded organic solutions by using different stripping agents showed that effective stripping is obtained upon using high concentration of nitric acid which oxidizes the extracted Cu(I) to Cu(II). In the present work, the forward extraction kinetics of Cu(II) from nitrate medium using CYANEX 302 in kerosene and kinetics of oxidative stripping of Cu(I)-CYANEX 302 chelate have been investigated using a Lewis cell. Extraction and stripping rates are governed by reactions at liquid–liquid interface rather than in the bulk phase. Extraction and stripping regimes are deduced to be chemical-controlled for Cu(II) and Cu(I). The different parameters affecting the extraction rate were separately studied and the extraction mechanism is discussed according to the dimeric model of CYANEX 302 in non-polar solvent. The stripping of Cu(I) from loaded organic solutions was achieved by using high concentration of nitric acid which oxidizes the extracted Cu(I) to Cu(II). Kinetic studies on the stripping of Cu(I) from loaded CYANEX 302 with nitric acid were also carried out using the same Lewis cell, and the mechanism of stripping process has been also proposed. From the temperature dependence of the rate measurement, the values of activation energy ( E), enthalpy change (Δ H) and entropy change (Δ S) are calculated for both systems.