Electrocatalytic Oxidation Degradation Of P-nitrophenol In Wastewater

In this paper, the electrocatalysts oxidation technology of p- nitrophenol polluted water had beeen studied. The p-nitrophenol was electrolyzed with constant electronic current in three-electrode non-membrane electrolytic cell with Ti/PbO——2 as anode, Ti plate as cathode, and saturated potassium chloride calomel electrode as reference electrode. The optimal conditions of temperature and pH, current density and PNP initial concentration were determined by orthogonal design experiments and change in single factor experiments. The results showed the most suitable conditions of electricity catalytic oxidation degradation of PNP is: PNP initial concertration is 1.0mmol/L, solution pH is 5, electrolysis temperature is 35℃, and current density is 40 mA/cm². Under these conditions, when the electrolysis time is 2.5 hour, the degradation ratio of PNP has reached 92.37 %.With high-performance liquid chromatography inspected in the process of electrolysis, the PNP and its degradation products of the middle of the electrolysis time change, then speculated the PNP degradation mechanism.To further increase the degradation ratio of PNP, some anions and cations were added to the electrolyte. The results show that Fe²⁺, Ni²⁺, Co²⁺ and Cl^-, ClO^-, BrO₃^- all can promote the degradation of the PNP, in another word, that has significantly improved compared to the direct electro-oxidation of PNP under the same conditions. Applied HPLC and HPIC to research PNP and its degradation products, and speculated the mechanism of indirect electro-oxidation of PNP.