Electrocatalytic Study Of Polypyrrole Nanowire Modified Electrode-Electrocatalytic Reduction Of Nitrite

Nitrite is widely existed in soil, water and food. It can change hemoglobin (HB) into methaemoglobin (FeIII) in men's body. Methaemoglobin can't carry oxygen, so men will be poisoned because of lacking oxygen. Nitrite also can react with amine to form product of N-nitrosoamines, and N-nitrosoamines is a carcinogenic substance. So it is necessary to study the method of detecting nitrite from aqueous solution. The chemically modified electrodes have been a most burgeoning and one of the most flourish research realms in the electrochemistry and electroanalytic chemistry since it was developed in the middle of 70's. It was for the moment widely applied in many cases such as life sciences, environmental science, analytic science and material science. The mediators modified on the surfaces of electrodes can realize the electrocatalytic reactions by accelerating electron transferring between redox centers and the electrode surface. Polypyrrole nanowires were modified on the surface of graphite electrode in by aqueous solution by the method of electrochemical synthesis. The electrochemical behavior of polypyrrole nanowire modified electrode was studied using the technique of cyclic voltammetry and chronoamperometry. The results show that the modified electrode has very good activity toward nitrite electroreduction. The electroreduction current is linearly dependent on the concentration of nitrite. The experimental parameters such as thickness of polypyrrole film, pH and temperature of the test solution, scan rate and coexisting anions what has effects on the reduction current were examined. The good linearity between the electroreduction current and the concentration of nitrite makes it possible to determine nitrite concentration accurately. Heteropolyanions, multiple negative charged anions, can be easily doped into PPy films as counterion. An amperometric nitrite sensor based on Phosphomolybdic acid / Polypyrrole (PPy) nanowire coated graphite electrode was studed. The length of the PPy nanowires, the temperature and acidity of the test solution, the electrolyte concentration and the charge of the corresponding anions were studied and it is found that these parameters have significant effects on the corresponding current density. The determination sensitivity may be varied according to the modification parameters and the determination conditions. Under a certain condition, the sensor shows linear respond towards nitrite.