A solar thermoelectric system by temperature difference for efficient removal of chromium (VI) in water and soil

In this work, we designed and developed a facile solar thermoelectric generator (STEG)-based system and a new electrokinetic remediation (EKR) system, which consists of main electrodes and unenergized auxiliary electrodes. The prepared nanocomposite was investigated for the effectiveness of the STEG+PANI-CNT/GF system in remediating Cr-contaminated. Photothermal performance test were applied in order to examine this STEG could export a power density of 365.56 mW/dm² and output potential of 801 mV at the temperature difference of 50 ℃. Thus the STEG could be used as the power to construct a Cr(VI) removal system using polyaniline (PANI) film/carbon nanotubes (CNT) modified graphite felt (GF) electrode (PANI-CNT/GF) as cathode and graphite rod as anode. The as-prepared STEG+PANI-CNT/GF system exhibited a significant Cr(VI) removal efficiency (96.2 % in water) through electromigration, electro-adsorption and electroreduction. Moreover, a multi auxiliary electrodes (AEs) system (STEG+PANI-CNT/GF+AEs) with six PANI-CNT/GF auxiliary electrodes was constructed in remediating Cr(VI)-contaminated soil, showing Cr(VI) removal efficiency of 16.7-60.1 % higher than that of STEG+PANI-CNT/GF. The PANI-CNT/GF auxiliary electrodes could bind Cr(VI) and adjust electric field distribution, contributing to adsorption and reduction of Cr(VI). Consequently, this work provides a promoting approach for heavy metals removal in future application.