Self-Enhanced Decomplexation of Cu-Organic Complexes and Cu Recovery from Wastewaters Using an Electrochemical Membrane Filtration System
Jiayi Li, Jinxing Ma, Ruobin Dai, Xueye Wang, Mei Chen, T. David Waite, Zhiwei Wang
Abstract
Heavy metals in industrial wastewaters are typically present as stable metal–organic complexes with their cost-effective treatment remaining a significant challenge. Herein, a self-enhanced decomplexation scenario is developed using an electrochemical membrane filtration (EMF) system for efficient decomplexation and Cu recovery. Using Cu-EDTA as a model pollutant, the EMF system achieved 81.5% decomplexation of the Cu-EDTA complex and 72.4% recovery of Cu at a cell voltage of 3 V. The •OH produced at the anode first attacked Cu-EDTA to produce intermediate Cu-organic complexes that reacted catalytically with the H2O2 generated from the reduction of dissolved oxygen at the cathode to initiate chainlike self-enhanced decomplexation in the EMF system. The decomplexed Cu products were further reduced or precipitated at the cathodic membrane surface thereby achieving efficient Cu recovery. By scavenging H2O2 (excluding self-enhanced decomplexation), the rate of decomplexation decreased from 8.8 × 10–1 to 4.1 × 10–1 h–1, confirming the important role of self-enhanced decomplexation in this system. The energy efficiency of this system is 93.5 g kWh–1 for Cu-EDTA decomplexation and 15.0 g kWh–1 for Cu recovery, which is much higher than that reported in the previous literature (i.e., 7.5 g kWh–1 for decomplexation and 1.2 g kWh–1 for recovery). Our results highlight the potential of using EMF for the cost-effective treatment of industrial wastewaters containing heavy metals.