Study On Electrochemical Electrode Behavior Of Nitrobenzene Compouds

In this paper, titania-bearing blast furnace slag (TBBFS), high-titania slag and concentrated titania ore (CTO) as semiconductor catalytic materials and graphite powder were prepared into carbon paste electrodes, and then electrochemical reaction of nitrobenzene on the carbon paste electrode by cyclic voltammetry, differential pulse, quasi-steady-state polarization curves and constant potential step was studied.In this paper, the effects of catalyst content, particle size and calcination temperature on the catalytic activity were investigated by cyclic voltammetry. Experiments show that in 0.5 mol/L sulfuric acid solution, the content of catalyst about 1% took on the best catalytic activity; the smaller size of catalyst particle, the better of catalytic activity; chengde steel slag, panzhihua steel slag, titanium slag which were not calcined took on the best catalytic activity; concentrated titania ore (CTO) which was calcined in the 400 to 600℃had the best catalytic activity; in the condition of the best catalytic activity, the order of catalytic activity of four raw materials:high-titania slag> concentrated titania ore (CTO)> panzhihua steel slag> chengde steel slag.The reaction of nitrobenzene on the carbon paste electrode by cyclic voltammetry and HPLC was studied. The results show that:the reaction of nitrobenzene which was reduced to aniline on the electrode was irreversible direct electrode reaction; the synergy of ultrasound and magnetic fields can speed up the reaction rate of reduction of nitrobenzene on the electrode; when the pH value of solution was changed, the mechanism of the reduction of nitrobenzene may be to change; Nitrobenzene electrode reaction were controlled by the diffusion steps; the rate of electrode reaction was accelerated by appropriately improving reaction temperature; the rate of nitrobenzene electrode reaction can be accelerated under 254nm UV irradiation. Through the quasi-steady-state polarization curves, when the carbon paste electrode was in acid medium, the apparent activation energy of reduction of nitrobenzene was 14.11 kJ/mol. Through the constant potential step analyzed:when the electrodes was in acid medium, the apparent activation energy of the gains and losses electron nitrobenzene reduction steps was 11.354 kJ/mol.Through the study of behavior of the electrode the possible formation of intermediate product during the process of degradation of nitrobenzene, we found that the redox reactions of these intermediate products were limited to functional group of benzene, and benzene was more difficult to direct oxidation; the potential the reduction of nitro-benzene was between-0.4 to -0.5 V. To the peaks of the reduction of nitrobenzene and aniline-for quantitative, differential pulse method was used for quantitative analysis, at 0.5mol/L sulfuric acid solution as bottom solution, the time of electrode stability was 150 s, scan rate was 100 mV/s, the concentration of nitrobenzene in the 5 to 160 mg/L and the peak current of reduction had a good linear relationship; the concentration of aniline in the 5 to 100 mg/L and the peak current of reduction had a good linear relationship. When the mixed solution of 0.5 mol/L of sulfuric acid and 100 mg/L of nitrobenzene was electrolysed in 120 minutes at constant potential of -0.4 V, the degradation rate of nitrobenzene could reach 38.70%, and the production rate of aniline was 33.19%.