Thermoelectric Generator-Driven Electrodeposition for Efficient Treatment of Low-Concentration Copper-Containing Wastewater
Industrial processes generate substantial low-grade waste heat and cold, which can be harnessed via thermoelectric generators (TEGs) based on the Seebeck effect. However, the low-voltage output of TEGs poses application challenges. This study investigates a TEG-driven electrodeposition system for efficient treatment of low-concentration copper-containing wastewater from electroplating, integrated circuit, and energy industries. The TEG system, comprising two series-connected semiconductor modules, achieved a maximum power of 0.36 W at a temperature difference (ΔT) of 130 °C. Optimal operating parameters for the coupled system were determined: ΔT = 90 °C, counter-current flow (two-side inlet), flow rate of 20 mL·min⁻¹, initial Cu²⁺ concentration of 500 mg·L⁻¹, and electrode gap of 0.7 cm. Under these conditions, after 60 min of electrodeposition, copper removal efficiency reached 99.42%, current efficiency was 67.93%, and the energy conversion efficiency of the TEG-electrodeposition system was 36.96%. The system also treated real copper-containing wastewater, achieving 95.83% removal within 100 min. Characterization via SEM, XRD, and XPS revealed that the electrodeposited product consisted of metallic copper and cuprous oxide, with metallic copper accounting for approximately 60%. This work provides a promising approach for utilizing industrial waste heat and cold to achieve low-energy, high-efficiency treatment of heavy metal wastewater.