Mouedhen G, Feki M, Wery M De Petris, Ayedi H F
Unité de Chimie Industrielle et Matériaux (UCIM), ENIS, B.P.W. Sfax, Tunisie.
J Hazard Mater. 2008 Jan 15;150(1):124-35. doi: 10.1016/j.jhazmat.2007.04.090. Epub 2007 Apr 24.
In the present work, electrocoagulation process with aluminum electrodes was investigated. Different operational conditions such as composition of Na(2)SO(4) based solutions, pH and current density were examined in a systematic manner. Their influence on (i) electrode polarization phenomena, (ii) pH evolution during electrolysis and (iii) the amount of Al released (coagulant) was investigated. For this purpose, potentiodynamic tests and electrolyses using different electrochemical cell configurations were conducted. It is mainly found that (i) a minimum Cl(-) concentration of the electrolyte of about 60ppm is required to breakdown the anodic passive film and considerably reduce the cell voltage during electrolysis; (ii) the anodic dissolution efficiency is unit; (iii) the global amount of coagulant (Al(3+)) generated has two origins: electrochemical oxidation of the anode and "chemical" attack of the cathode and (iv) electrolysis with Al electrodes acts as pH neutralization of the electrolytic medium. Taking into account advantage of the pH evolution observed during electrolysis, electrocoagulation tests were performed to treat a synthetic wastewater containing heavy metallic ions (Ni(2+), Cu(2+), Zn(2+)). Removal efficiencies over 98% were reached. Furthermore, our results displayed prominently that an increase of current density notably reduces the treatment duration without inducing a strong increase of the charge loading.
在本研究中，对铝电极电凝聚过程进行了研究。系统地考察了不同操作条件，如基于Na₂SO₄溶液的组成、pH值和电流密度。研究了它们对（i）电极极化现象、（ii）电解过程中的pH值变化以及（iii）铝释放量（凝聚剂）的影响。为此，进行了动电位测试以及使用不同电化学池配置的电解实验。主要发现如下：（i）电解质中Cl⁻浓度至少约为60ppm才能破坏阳极钝化膜并在电解过程中显著降低电池电压；（ii）阳极溶解效率为单位值；（iii）产生的凝聚剂（Al³⁺）总量有两个来源：阳极的电化学氧化和阴极的“化学”侵蚀；（iv）用铝电极进行电解可实现电解介质的pH值中和。考虑到电解过程中观察到的pH值变化优势，进行了电凝聚试验以处理含重金属离子（Ni²⁺、Cu²⁺、Zn²⁺）的合成废水，去除效率达到了98%以上。此外，我们的结果显著表明，电流密度的增加显著缩短了处理时间，而不会导致电荷负载大幅增加。
