Electrocatalytic Reduction Of NO₃～- Based On Polypyrrole Nanowires Modified Electrode

As an inherently conducting polymer, polypyrrole has promising applications in many fields, such as in sensors and electrocatalytic fields. Electrodes modified with porous conducting polymer nanowires provide much more active sites for immobilization of catalyst and reation than ordinary electrodes do. The researches on polypyrrole nanowire modified electrode will provide helpful information for electrocatalytic reation of a certain substance, which makes it important for theory study and practical application to synthesize and apply polypyrrole nanowires. Nitrate is a common contaminant in water-body. Nitrate can be microbially reduced to nitrite, which is an essential precursor in the formation of nitrosamines, many of which have been shown to be potent carcinogens. The study of electrocatalytic performance of polypyrrole nanowires modified electrode towards nitrate should have significant effects on electrochemical catalytic process of conductive polymers.The electrocatalytic reduction of nitrate based on polypyrrole nanowires modified electrodes was developed. The reduction over-potential of nitrate is reduced, and nitrate sensor operated at -0.15 V was developed. Further more, removal of nitrate by electrolysis method was carried out under the potential range of -1.2 and -2.4 V. The effects of preparation parameters of PPy nanowire modified electrodes on electrochemical sensor performance were studied. The experimental results show that scanning rate, polymerization upper potential, circle number of cyclic voltammetric polymerization, temperature of polymerization and polymerization time, etc. have significant effects on the morphology of PPy, and consequently effective surface area of the electrode and electroreduction current density of nitrate. The experimential results also indicate that polymerization solution parameters such as concentration of pyrrole, concentration of electrolyte, acidity of polymerization solution, the kinds and concentration of dopants and the"memory effect"of NO₃^- have significant effects on the morphology of PPy nanowires and electroreduction current density of nitrate.Amperometric determination of nitrate based on electrochemical solid-phase extraction was established. The determination sensitivity and detection limit under the optimized condition is 606.54 mA/mol·L^-1cm² and 9.98×10^-6 mol·L^-1, respectively. The proposed method was successfully applied to determination of nitrate in the real samples, and the obtained result has no obvious difference with that of Ion...