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

Abstract

In order to enhance Cu−EDTA decomplexation and copper cathodic recovery via the photoelectrocatalytic (PEC) process, S 2 O 8 2− was introduced into the PEC system with a TiO 2 /Ti photoanode. At a current density of 0.2 mA/cm 2 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 S 2 O 8 2− addition into the PEC process (PEC/S 2 O 8 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 S 2 O 8 2− into SO 4 ·− radicals by cathodic reduction occurred, which was prior to the reduction of liberated Cu 2+ ions. UV irradiation of S 2 O 8 2− also led to the production of SO 4 ·− . The generated SO 4 ·− radicals enhanced the oxidation of Cu−EDTA. After the consumption of S 2 O 8 2− , the Cu recovery via cathodic reduction proceeded quickly. Acidification induced by the transformation of SO 4 ·− to OH· favored the copper cathodic recovery. The combined PEC/S 2 O 8 2− process was also efficient for the TOC removal from a real electroplating wastewater with the Cu recovery efficiency higher than 80%.

Enhancement of photoelectrocatalytic degradation of diclofenac with persulfate activated by Cu cathode

“…However, the mechanism remained unclear about the interaction between PS and PEC reaction. Zeng et al reported that PS was added to a photoelectrocatalytic system driven by UV light in order to enhance the Cu-EDTA decomplexation and Cu recovery [25]. This paper indicated the PS activation through cathodic electron and served as a bridge between two techniques.…”

Persulfate enhanced photocatalytic degradation of bisphenol A by g-C3N4 nanosheets under visible light irradiation

“…Recently, persulfate (PS), a kind of oxidant agent, was used for in situ chemical oxidation in the remediation of organic pollutants in aqueous systems (Ahmad et al, 2013;Hazimea et al, 2013). A large number of studies showed that PS can be active by UV, heat, alkaline, transition metals to produce sulfate radicals (SO 4 À ) and hydroxyl radicals ( OH) (Chen and Huang, 2015;Hazimea et al, 2013;Waldemer et al, 2007;Zeng et al, 2016;Hu et al, 2016), which have high redox potential and can destroy most of organic compounds efficiently. Hu and tian investigated the g-C 3 N 4 /Fe(III)/ PS system which found that the phenol degradation efficiency can be significantly improved by combing photocatalysis and light Fenton interaction (Hu et al, 2016).…”

A Bifunctional Electroactive Ti4O7-Based Membrane System for Highly Efficient Ammonia Decontamination

“…The successful deposition of Cu onto the NF can be verified by the Cu 2p XPS spectra. As displayed in Figure S4d, the signals located at 931.8 eV and 953.0 eV were assignable to the emissions from Cu 2p 3/2 and Cu2p 1/2 levels, which corresponded to the typical binding energy of Cu 0 [19]. Other binding energies present at 934.4 eV for Cu 2p 3/2 and 954.0 eV for Cu 2p 1/2 were ascribed to Cu 2+ [6,20].…”