The coupled removal of heavy metals from electroplating wastewater induced stable electricity generation during long-time discharging in a three-chamber thermally regenerative battery

Abstract

The low cathode Cu2+ concentration and ammonia crossover jointly cause the unstable discharge, severely limiting the practical application of thermal regenerative batteries (TRBs). In order to solve this problem, an intermediate chamber coupled with the removal of heavy metals from electroplating wastewater is introduced to construct the three-chamber thermally regenerative battery (TRB-3C). The results demonstrate that it is feasible to achieve a stable electricity generation for 3 h discharging with simultaneously high-efficient Cu2+ removal from wastewater, which is due to the intermediate chamber induced continuous Cu2+ supplementation to cathode and the alleviated ammonia crossover. A nearly five-fold promotion of the maximum performance of the battery and a high Cu2+ removal efficiency of 94.6% is obtained by using a flow middle chamber with a reduced thickness and hierarchical porous composite electrodes. With the increase of Cu2+ concentration in the wastewater, a significantly improved stable discharge is found while the removal efficiency decreased due to the required long time for the treatment. With respect to the removal, high-concentration Cu2+ wastewater can be effectively treated through the multi-batch operation. Besides, TRB-3C also shows a good removal of other metal ions in the electroplating wastewater.