钛基修饰电极催化电解去除水中硝酸盐氮的研究

利用热分解法制备CuO修饰Ti基阴极和SnO2-Sb2O5修饰Ti基阳极,组成无隔膜电解体系,以模拟废水(NO3--N 50mg/L)为对象,进行了水中NO3--N去除实验研究.结果数据表明,CuO修饰Ti基阴极对水中NO3--N的去除率随电流密度、极板间距、搅拌强度和电解时间增加而增加,在电流密度10mA/cm2、极板间距9mm、中等搅拌强度下电解150min,NO3--N催化还原去除率可达93.8%.Cl-支持电解可使NO3--N催化还原产物NH4+-N氧化为N2-N去除.在电流密度10mA/cm2、极板间距9mm、NaCl添加量600mg/L、中等搅拌强度下电解120min后,NO3--N和TN的去除率达到89.3%和86.9%,NO2--N和NH4+-N未检出.分析认为NO3--N还原机制为NOx中O被阴极表面Cu吸附固定,N—O键受氢攻击破坏,逐步还原.阳极电解Cl-生成HOCl,HOCl氧化NH4+-N成N2-N.

Catalytic electrolysis removal of nitrate in water by modified Ti substrate electrodes

A comprehensive experimental study was conducted to investigate a new method of NO3--N removal in a septum-free electrolysis system based on simulated wastewater, i.e. 50mg/L NO3--N. CuO modified-Ti and SnO2-Sb2O5 modified-Ti were prepared via pyrolyticprocess and adopted as cathode and anode, respectively. CuO modified-Ti cathode could work as catalyst to reduce NO3--N and the resulting rate of removal increased with the increasing in current density, space between electrodes, stirring intensity and reaction time. A high rate of removal (93.8%) was obtained when applying current density at 10mA/cm2, space between electrodes at 9mm, stirring intensity at middle-scale for 150 min. In addition, NH4+-N which was the reduction product of NO3--N could be oxidized to N2-N under the support electrolysis of Cl-. With a starting NaCl concentration at 600mg/L, current density at 10mA/cm2, space between electrodes at 9mm, stirring intensity at middle-scale for 120 min, the removal rate of NO3--N and TN is 89.3% and 86.9%, respectively, and no NO2--N or NH4+-N were detected. The NO3--N reducing mechanism may be O in NOx fixed by Cu adsorbing, then gradual reduced via reductant attacking N—O. In addition, NH4+-N oxidized to N2 due to the HOCl generation from anode electrolysis of Cl-