The main purpose of this article is to study the behavior of a metallic electrode in the electrolyte which contains a surface-active substance with the property of adsorbtion-desorbtion, in the galvanodynamic and pote...The main purpose of this article is to study the behavior of a metallic electrode in the electrolyte which contains a surface-active substance with the property of adsorbtion-desorbtion, in the galvanodynamic and potentiodynamic rejimes. The study of the electrochemical behavior of a metallic electrode is carried out by operational impedance method, based on the Ohms low on the interaction between the Laplace-transformed expression of current, voltage and complex resistance (impedance). It is obtained the analytical expression of interface voltage-time dependence in a solution which contains a surface-active indifferent substance with the property of adsorbtion-desorbtion;also it is obtained the analytical expression of current density-time dependence which is passing through electrochemical cell in potentiodynamic regime of functioning of the Frumkin- Melik-Gaykazan model. It is established that the relation between the interface metallic electrode-indifferent electrolyte with property of adsorbtion-desorbtion voltage in the galvanodynamic rejime has the character of second order parabola;the relation between current density which is passing through a cell and time in potentiodynamic rejime of functioning in the Frumkin-Melik-Gaykazan model has exponential character.展开更多
The formation kinetics of the self-assembled monolayer (SAM) of an azobenzenealkanethiol,denoted as AzoC2SH on surface was studied using electrochemical techniques,and the monolayers prepared at different assembly tim...The formation kinetics of the self-assembled monolayer (SAM) of an azobenzenealkanethiol,denoted as AzoC2SH on surface was studied using electrochemical techniques,and the monolayers prepared at different assembly times and concentration were also investigated.A two-step adsorption kinetics has been confirmed:the fast adsorption process and the following long-term reorganization.The equilibrium constant(K)for the adsorptioon and the interaction factor between adsorbate-adsorbate molecules () were evaluated based on the Frumkin isotherm and determined to be (3. 17±0. 13)× 106 mol.L(-1) and -0.34±0.04, respectively The Gibbs free energy (G)of SAM was determined to be -(37. 07±0. 13)kJ.mol(-1)展开更多
The 1-octyl-3-methylimidazolium chloride, [C8 mim][Cl] ionic liquid(IL) was used as a novel surfactant in n-heptane/water system. The interfacial tensions(IFT) were measured and corresponding variations were investiga...The 1-octyl-3-methylimidazolium chloride, [C8 mim][Cl] ionic liquid(IL) was used as a novel surfactant in n-heptane/water system. The interfacial tensions(IFT) were measured and corresponding variations were investigated. An IFT reduction of 80.8% was appropriate under the IL CMC of about 0.1 mol·L^-1 and stronger effects were achieved when magnetite nanoparticles and salts were present profoundly under alkaline p Hs.The equilibrium IFT data were accurately simulated with the Frumkin adsorption model. Hereafter, the saturated surface concentration, equilibrium constant and interaction parameter were obtained and their variations were demonstrated. Further, emulsion stability and contact angle of oil/water interface over quartz surface were studied. The oil/water emulsion stability was hardly changed with nanoparticles;however, the stability of oil/water + IL emulsions was significantly improved. It was also revealed that the presence of sodium and calcium chloride electrolytes fortifies the IL impact, whereas sodium sulfate weakens. From dynamic IFT data and fitting with kinetic models, it was found that the IL migration toward interface follows the mixed diffusion–kinetic control model. Consequently, the IL diffusion coefficient and the appropriate activation energy were determined.展开更多
文摘The main purpose of this article is to study the behavior of a metallic electrode in the electrolyte which contains a surface-active substance with the property of adsorbtion-desorbtion, in the galvanodynamic and potentiodynamic rejimes. The study of the electrochemical behavior of a metallic electrode is carried out by operational impedance method, based on the Ohms low on the interaction between the Laplace-transformed expression of current, voltage and complex resistance (impedance). It is obtained the analytical expression of interface voltage-time dependence in a solution which contains a surface-active indifferent substance with the property of adsorbtion-desorbtion;also it is obtained the analytical expression of current density-time dependence which is passing through electrochemical cell in potentiodynamic regime of functioning of the Frumkin- Melik-Gaykazan model. It is established that the relation between the interface metallic electrode-indifferent electrolyte with property of adsorbtion-desorbtion voltage in the galvanodynamic rejime has the character of second order parabola;the relation between current density which is passing through a cell and time in potentiodynamic rejime of functioning in the Frumkin-Melik-Gaykazan model has exponential character.
文摘The formation kinetics of the self-assembled monolayer (SAM) of an azobenzenealkanethiol,denoted as AzoC2SH on surface was studied using electrochemical techniques,and the monolayers prepared at different assembly times and concentration were also investigated.A two-step adsorption kinetics has been confirmed:the fast adsorption process and the following long-term reorganization.The equilibrium constant(K)for the adsorptioon and the interaction factor between adsorbate-adsorbate molecules () were evaluated based on the Frumkin isotherm and determined to be (3. 17±0. 13)× 106 mol.L(-1) and -0.34±0.04, respectively The Gibbs free energy (G)of SAM was determined to be -(37. 07±0. 13)kJ.mol(-1)
基金financial support by the Bu-Ali Sina University to carry out this research.
文摘The 1-octyl-3-methylimidazolium chloride, [C8 mim][Cl] ionic liquid(IL) was used as a novel surfactant in n-heptane/water system. The interfacial tensions(IFT) were measured and corresponding variations were investigated. An IFT reduction of 80.8% was appropriate under the IL CMC of about 0.1 mol·L^-1 and stronger effects were achieved when magnetite nanoparticles and salts were present profoundly under alkaline p Hs.The equilibrium IFT data were accurately simulated with the Frumkin adsorption model. Hereafter, the saturated surface concentration, equilibrium constant and interaction parameter were obtained and their variations were demonstrated. Further, emulsion stability and contact angle of oil/water interface over quartz surface were studied. The oil/water emulsion stability was hardly changed with nanoparticles;however, the stability of oil/water + IL emulsions was significantly improved. It was also revealed that the presence of sodium and calcium chloride electrolytes fortifies the IL impact, whereas sodium sulfate weakens. From dynamic IFT data and fitting with kinetic models, it was found that the IL migration toward interface follows the mixed diffusion–kinetic control model. Consequently, the IL diffusion coefficient and the appropriate activation energy were determined.
