Research On The Characteristic Of Electrochemical Degradation Of Nitrophonels In Aqueous Solution

The electrolysis process has attracted a great deal of attention recently, mainly because of its ease of control, amenability to automation, high efficiency and environment compatibility. Nitrophenols are among the most common organic pollutants in industrial and agricultural wastewaters. The current study of nitrophenols focus on p-nitrophenol (PNP) and o-nitrophenol (ONP), but there is few study of m-nitrophenol(MNP).With the method of undivided/divided electrolysis cell, this paper studied the electrolytic degradation of nitrophenlos using Ti/Pt as anode and stainless steel plate as cathode. The electrolytic degradation was carried out galvanostatically. The influences of key factors such as pH, current density have been investigated in an undivided electrolysis cell. Under different pH conditions, the degradation processes of nitrophenlos have been investigated with undivided cell.The experimental results showed that increasing current density, the degradation efficiency of nitrophenols was improved. But when the current densities are 20and 30mA/cm2 respectively, the nitrophenols conversion was almost the same, which indicated that subsidiary reaction is more enhanced than positive reaction. The optimum parameters are pH of 2.0, current density of 20mA/cm2. Under these optimum conditions of electrochemical degradation, the degradation pathways of nitrophenols were discussed. In divided cell, ONP was first reduced for 3 hours and then oxidated for 2 hours. The ONP reomoval and COD removal were higher than undivided cell.Cyclic valtammetry showed that the nitrophenols were mainly oxidated by·OH. By HPLC, amino-phenols and benzenediols have been found. In the anodic cell, nitrophenols were firstly oxidateb into benzenediols then the ring cleavage reactions took place. In the cathodic cell, nitrophenols were firstly reduced into amino-phenols then the amnio-phenols were oxidated into benzenediols by anode.