Chinese Journal of Chemical Engineering, Vol.28, No.1, 271-278, 2020
Chlorine-free emission disposal of spent acid etchant in a three-compartment ceramic membrane reactor
Electrochemical technologies for the on-site treatment of spent acid etchant have received great attention due their ease of operation and economic benefits. On the other hand, a large amount of Cl-2 is generated during the electrolysis process, which leads to potential environmental risks. In the present work, a novel three-compartment ceramic membrane flow reactor, including a cathode chamber, an anode chamber, and a gas absorption chamber was developed. The three chambers were divided by an Al2O3 ceramic membrane and a breathable hydrophobic anode diffusion electrode (ADE). The Cl-2 evolution onset potential of the ADE was increased to 1.19 V from 1.05 V of the graphite fell, effectively inhibiting the chlorine evolution reaction (CER). The anode-generated Cl-2 diffused into the gas absorption chamber through the ADE and was eventually consumed by the H2O2 adsorbent. Cu could be recovered without emitting chlorine due to the special structure of reactor. The current efficiency of copper precipitation and cathode reduction from Cu2+ to Cu+ reached 97.7% at a working current of 150 mA. These results indicated that the novel membrane reactor had high potential for application in the copper recovery industry. (C) 2019 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.