Abstract
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•Perchlorate could be effectively reduced to chloride by Re-Pd/BC particle electrode.•The sorption kinetics of Re-Pd/BC could be increased by using benzalkonium chloride.•Superfluous oxygen, high pH and coexisting nitrate were harmful to reduction.•Existing form of Re and Pd, H∗ and current-density played a critical role in reduction.
This work had demonstrated a novel and high-efficiency perchlorate reduction particle electrode using benzalkonium chloride as dynamics strengthener and coupling with rhenium (Re) and palladium (Pd) nanoparticles (Re-Pd/BC). Perchlorate ions could be rapidly adsorbed in the presence of benzalkonium chloride, facilitating its subsequent reduction on the Re-Pd/BC particle electrode. On the basis of the characterization results and kinetics analysis, a synergistic effect of Re and Pd was observed, perchlorate could be efficiently reduced and completely converted into chlorine in optimized conditions (pH 3.0, anaerobic and current density 20 mA/cm2) and the reduction rate constant of Re-Pd/BC was 0.9451 L−1 gcat−1. The superfluous oxygen in solution could lead to Re-Pd/BC deactivation, and increased current density was beneficial of electro-reduction. The increased pH lead to decrease of reduction efficiency, and the coexisting anion of nitrate could be competed with perchlorate for reduction sites which lead to decrease of reduction rate. Based on the experimental results, it was found that the existing form of Re and Pd on the surface of Re-Pd/BC, the number of atomic H∗ and current density played an important role in perchlorate electro-reduction process.