电化学脱硝过程参数的响应曲面优化研究

以Ti/IrO2-TiO2-RuO2为阳极,Cu/Zn合金电极为阴极,在无隔膜电解池中对这一新构造电极对的脱硝氮性能进行了研究。为了有效结合阴极硝氮还原能力和阳极氧化能力,采用响应曲面法中的Box-Behnken设计优化了对电化学脱硝过程有显著影响的4个重要因素:氯化钠含量、电流密度、pH和初始硝氮浓度。优化结果表明,相对于pH和初始硝氮浓度,氯化钠含量和电流密度对脱硝性能影响更大,而阴极硝氮还原性能主要受初始硝氮浓度、pH的影响。以6 h内电极对脱氮百分率为响应量,优化得最佳电化学脱硝过程参数为:氯化钠含量,1 g/L;电流密度,24.99 mA/cm2;pH,1.81;初始硝氮浓度100 mg/L。在此实验条件下,6 h内电极对脱氮百分率预测值为99.84%。通过3次重复验证实验,确认实际6 h内电极对脱氮百分率为91.34%。预测值与实测值两者相差不大,由此可知,Box-Behnken设计是一种优化电化学脱氮实验参数的有效方法,经过优化后的电极对具有较佳的脱氮效率。

Optimization of electrochemical denitrification process parameters with Box-Behnken design

This study investigated the performance of electrochemical denitrification using Ti/IrO₂-TiO₂-RuO₂ as the anode and Cu/Zn as the cathode in an undivided cell. In order to obtain an ideal performing condition of cathodic reduction of nitrate and anodic oxidation of the formed by-product, Box-Behnken design of response surface method was employed to optimize the factors that were NaCl dosage, current density, pH and initial nitrate concentration and which were proved to have a significant effect on electrochemical nitrate removal. Current density and NaCl dosage had stronger effects on nitrate removal efficiency than initial nitrate concentration and pH in the present study. The optimal value of NaCl dosage, current density, pH and initial nitrate concentration for nitrate removal efficiency are 1 g/L, 24.99 mA/cm², 1.81 and 100 mg/L, respectively, at which the predicted nitrate removal efficiency after 6 h electrolysis calculated with the fitted equation is 99.84%, as against the actual nitrate removal efficiency of 91.34% which was obtained through duplicate confirmatory experiments. The difference between the predicted and actual nitrate removal efficiency is minor, indicating Box-Behnken design can be effectively used to optimize the design for experiments on the electrochemical reduction of nitrate.