Aplicação de Processos Eletroquímicos Oxidativos Avançados (PEOA) para degradação do complexo EDTA-Ni(II)

Abstract

In wastewater , the presence of metal ions can delay the degradation of organic contaminants. On the other hand , the metal recovery efficiency can be reduced in the presence of organic species. According to the literature, ethylenediamine tetraacetic acid (EDTA) is resistant to biodegradation, being persistent in the environment. In this study, the electrochemical degradation of the EDTA-Ni (II) complex was performed, using a bench scale electrochemical cell, a Dimensionally Stable Anode (DSA®) (Ti/Ru0,.3Ti0,7O2) and a Ti plate counter electrode. The supporting eletrolyte was NaCl and constant current electrolysis was performed. The best effect of the NaCl concentration and the current applied was obtained by employing an experimental design. Degradation tests were followed by analysis of COD , TOC and Phytotoxicity. From the experimental design, it was concluded that the optimal concentration of NaCl was 79,281 g L-1 and best applied current was 95 mA. The photoassisted degradation process allowed the degradation of the EDTA-Ni (II) complex, leading to the TOC removal of approximately 70% and COD removal of 47%. The phytotoxicity tests showed no generation of toxic degradation products against the test organism (Lactuca sativa). The results showed that the degradation of the complex and recovery of nickel ions simultaneously is possible, but for total mineralization, long-term tests should be performed.