铁粉去除电镀废水中锌镉离子的反应动力学研究

Study on Reaction Kinetics of Treatment Zinc Cadmium Ions in Electroplating Wastewater by Iron

摘要: 以商业级还原性铁粉为原材料对某公司的含锌镉电镀废水进行了正交试验研究。结果表明：影响锌、镉离子去除率的主要因素为pH和铁的投加量，次要影响因素为反应时间和反应物初始浓度。去除镉的最佳组合条件是pH为5，浓度为20 mg/L，铁的投加量为50 mg/L，反应时间达到1.5 h以上时，镉的去除率达到98.2%；去除锌的最佳组合条件是pH为9，浓度为20 mg/L，铁的投加量为75 mg/L，反应时间达到0.5 h以上时，锌的去除率达到95.4%。反应动力学研究表明：还原性铁粉去除锌、镉体系均符合准一级反应动力学。反应速率随着锌初始浓度、pH值和投加量的增加而升高，随着镉初始浓度和pH值的升高而降低，随着还原性铁粉投加量的增加而升高。

Abstract: Commercial-grade iron powder as a raw material for reducing electroplating wastewater was studied. The orthogonal test showed: the main factors of zinc of cadmium ions’ removal rate are pH and dosage of iron, and the secondary factors are reaction time and initial concentration. Cadmium is the best combination of pH 5 at a concentration of 20 mg/L, the dosage of iron is 50 mg/L, the reaction time to reach more than 1.5 h, cadmium’s removal rate reaches 98.2% under these conditions. Zinc is the best combination of pH 9 at a concentration of 20 mg/L, the dosage of iron is 75 mg/L, the reaction time to reach more than 0.5 h, zinc’s removal rate reaches 95.4%. Reaction kinetics tests showed that the removal of Zn and Cd from the reduced iron powder was consistent with the pseudo first order reaction kinetics. The reaction rate increases with the increase of initial zinc concentration, pH value and dosage, and decreases with the increase of initial cadmium concentration and pH value, and increases with the increase of the amount of reduced iron powder.