Due to its high chemical stability,good thermal resis ta nce, ideal conductivity and ion-selective permeability, Nafion membrane has bee n used in many electrochemical systems.The significant progress has been made in the applied research of Nafion membranes in fuel cell, membrane separation and organic electro-synthesis.For organic electro-synthesis,the studies on permeat ion of organic compounds through the membrane were seldom reported in literature .3-methylpyridine is the main raw material for electrochemical synthesis of nia cin.In this work, the permeating fluxes of 3-methylpyridine were measured in th e H 2SO 4 aqueous solution at different concentrations and temperatures.The re sults showed that the permeating flux was directly proportional to the molar con centration of 3-methylpyridine at a given temperature.The relationship between the natural logarithm of proportional coefficient and the reciprocal of temperat ure was linear.The Arrhenius equation for the relationship between permeating fl ux and temperature was obtained.The apparent activation energy and apparent pre -exponential factor were estimated as 63.3 kJ·mol -1 and 2.69×108 m ·h -1.
A new green technology of producing chromic anhydride with an electrochemical synthesis method was studied to solve the pollution problems in the traditional production process of chromic anhydride.The anolyte used was sodium dichromate solution, and the anode used was a self-made combination electrode of titanium matrix with a multiple-unit metal oxides active coating.The electrochemical behavior of sodium dichromate solution on a combination electrode of titanium matrix was studied with cyclic voltammetry as a part of the fundamental researches of this technique.The electrooxidation reaction of 160 cycles indicated that the electrode possessed a very stable electrochemical behavior.The peak currents ip and peak potentials Ep of the oxidation peaks for sodium dichromate solution of different concentrations, i.e., water under the existence of sodium dichromate, were experimentally measured at different temperatures and sweep rates v on the electrode.The equations of peak current ip versus v1/2 and peak potential Ep versus lnv were established, indicating that the electrode reaction was an irreversible diffusion-controlled reaction.The kinetic parameters and activation energy of electrode reaction was calculated, and the effects of temperature on the kinetic parameters and activation energy were preliminarily discussed.
A new green technology of producing chromic anhydride with an electrochemical synthesis method was studied to solve the pollution problems in the traditional production process of chromic anhydride.A self-made electrosynthesis reactor of pure titanium and stainless steel, with a multiple-unit metal oxides combination anode, a cathode of stainless steel, and a reinforced combination cation exchange membrane with perfluorosulfonic and perfluorocarboxylic polymers was used to carry out, the direct electrochemical synthesis experiment of chromic anhydride from sodium dichromate.From the experimental results and the principle of electrochemical reaction, it was found that the process of electrochemical synthesis reaction of chromic anhydride might be quantitatively followed by the variation of operating voltage measured macroscopically with reaction time. Operating voltages were experimentally measured at the different initial sodium dichromate concentrations of the anolyte in the electrosynthesis process of chromic anhydride, and the variation of operating voltage with reaction time was discussed. The mathematical model of the variation of operating voltages with reaction time and the rate of change equations of operating voltage were established.The model characterizes the change of operating voltages in the electrosynthesis process of chromic anhydride, and provideds the foundations for the further study and process monitoring of the electrochemical synthesis of chromic anhydride.
