靛蓝废水无机盐环境下铝极板溶解与电化学行为分析

Analysis of aluminum electrode dissolution and electrochemical behavior in inorganic salt environment of indigo wastewater

为提升靛蓝染色废水电絮凝效率,确定电絮凝过程中最佳水解金属盐形态形成条件,采用Al-Ferron逐时络合比色法探讨电絮凝过程中初始pH、共存阴离子种类、电流密度对铝盐形态分布的影响,同时监测絮体Zeta电位、终止pH、体系电流密度与电导率的变化。通过显微镜观察电极溶解腐蚀情况,利用电化学工作站测定电极的极化曲线与电化学阻抗谱,分析其电化学行为。结果表明,靛蓝废水电絮凝过程中,最佳初始pH范围为6~7,此时具有优势絮凝形态的中聚合态铝(Al_(b))含量较高;Cl–的加入可抑制电极钝化,提升电絮凝反应速率;低电流密度有利于电极均匀腐蚀和Al_(b)的存在,当电流密度为15 m A/cm(2)时体系内Al_(b)含量达4.76 mg/L,可产生较好的絮凝效果。

In order to improve the electrocoagulation efficiency of indigo dyeing wastewater,and determine the optimal formation conditions of hydrolyzed metal salts,the Al-Ferron timed spectrophotometry was used to investigate the influence of initial pH,coexisting anion species,and current density on the distribution of aluminum salts during electrocoagulation.Meanwhile,the changes of floc Zeta potential,termination pH,system current density and conductivity were monitored.The dissolution and corrosion of the electrode were observed microscopically,and the electrochemical behavior was analyzed by measuring the electrode polarization curve and electrochemical impedance spectroscopy using an electrochemical workstation.The results showed that,when the initial pH range was 6~7 during the electrocoagulation,the content of medium polyaluminum(Al_(b))with the dominant flocculation form was higher.The addition of chloride ions inhibited the electrode passivation and enhanced the electrocoagulation reaction rate.The low current density was beneficial to the uniform corrosion of electrode and the existence of Al_(b).The content of Al_(b)in the system could reach 4.76 mg/L at a current density of 15 mA/cm^(2),which could produce good flocculation.