Enhanced Photoelectrocatalytic Decomplexation of Cu–EDTA and Cu Recovery by Persulfate Activated by UV and Cathodic Reduction

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• 作者：Huabin Zeng ; Shanshan Liu ; Buyu Chai ; Di Cao ; Yan Wang ; Xu Zhao
• 刊名：Environmental Science & Technology
• 出版年：2016
• 出版时间：June 21, 2016
• 年：2016
• 卷：50
• 期：12
• 页码：6459-6466
• 全文大小：621K
• 年卷期：0
• ISSN：1520-5851

文摘

In order to enhance Cu–EDTA decomplexation and copper cathodic recovery via the photoelectrocatalytic (PEC) process, S₂O₈^2– was introduced into the PEC system with a TiO₂/Ti photoanode. At a current density of 0.2 mA/cm² and initial solution pH of 3.0, the decomplexation ratio of Cu complexes was increased from 47.5% in the PEC process to 98.4% with 5 mM S₂O₈^2– addition into the PEC process (PEC/S₂O₈^2–). Correspondently, recovery percentage of Cu was increased to 98.3% from 47.4% within 60 min. It was observed that nearly no copper recovery occurred within the initial reaction period of 10 min. Combined with the analysis of ESR and electrochemical LSV curves, it was concluded that activation of S₂O₈^2– into SO₄^·– radicals by cathodic reduction occurred, which was prior to the reduction of liberated Cu²⁺ ions. UV irradiation of S₂O₈^2– also led to the production of SO₄^·–. The generated SO₄^·– radicals enhanced the oxidation of Cu–EDTA. After the consumption of S₂O₈^2–, the Cu recovery via cathodic reduction proceeded quickly. Acidification induced by the transformation of SO₄^·– to OH· favored the copper cathodic recovery. The combined PEC/S₂O₈^2– process was also efficient for the TOC removal from a real electroplating wastewater with the Cu recovery efficiency higher than 80%.