电絮凝处理甲基橙废水的实验及动力学模型

采用电絮凝法处理甲基橙模拟染料废水，研究了染料脱色的影响因素及其COD_Cr去除动力学。考察了静置时间、槽电压、极板间距、初始浓度、pH值以及电解质浓度对甲基橙染料脱色效率的影响。结果表明，槽电压为20 V，电流为0.4 A，极板间距为2.5 cm，废水体积为500 ml，甲基橙初始浓度为500 mg·L^-1，溶液pH值为3.0，电解质KCl的浓度为0.5 g·L^-1时，反应10 min后甲基橙脱色率可达97 %。根据电絮凝的絮凝沉淀理论和氧化反应机理，建立COD_Cr去除反应动力学模型，模型与实验数据拟合较好。通过模型参数的预测可以揭示甲基橙降解主要以絮凝沉淀为主，氧化降解为辅，同时溶液中二价铁Fe(II)的增加会影响COD_Cr去除率的下降。

Experiment and kinetic model for methyl orange wastewater removal by electrocoagulation

The methyl orange (MO) simulated dye wastewater was treated by electrocoagulation. The effect of operation parameters on MO decolorization and the kinetic model of chemical oxygen demand (COD_Cr) removal were investigated. Operation parameters, such as input voltage, electrode distance, initial MO concentration, electrolyte concentration and pH, were investigated based on the decolorization efficiency of MO. Experimental results showed that up to 97% of color decay was obtained after 10 min reaction with input voltage of 20 V, current of 0.4 A, electrode distance of 2.5 cm, treated volume of 500 ml, initial MO concentration of 500 mg·L^-1, electrolyte KCl concentration of 0.5 g·L^-1 and pH of 3.0. A kinetic model for COD_Cr reduction was established based on the coagulation and oxidation processes. The experimental data fitted well with the model curves. The parameters predicted from the kinetic model showed that the coagulation process was the main pathway for COD_Cr removal and the oxidation process was the next. In addition, the increase of Fe²⁺ in the solution decreased the COD_Cr removal.