Electrocatalytic dechlorination of florfenicol using a Pd-loaded on blue TiO2 nanotube arrays cathode

Electrocatalytic hydrodechlorination technology provides an attractive strategy to effectively eliminate the biotoxicity of halogenated organic pollutants (HOPs). Herein, we demonstrated a highly dispersed Pd loaded on blue TiO2 nanotube arrays (Pdx-BTNA) cathode that can achieve efficient dechlorination and detoxification toward florfenicol (FLO). Characterization results indicated that strong interaction between Pd and BTNA was achieved through Pd-O bonds, which facilitated the electron transfer rate. Pdx-BTNA significantly outperformed other cathodes (i.e., BTNA, Pdx-TNA and Pdx-Ti) in the electrocatalytic dechlorination of FLO due to enhanced utilization of active H*. The dechlorination performances of FLO well followed the pseudo-first-order kinetic, and the reaction constant rate on Pdx-BTNA cathode (0.035 min-1) was 17.5, 1.94, 7.0 times higher than that on BTNA, Pdx-TNA and Pdx-Ti cathodes, respectively. Quenching experiments and electrochemical characterization indicated that both direct electron transfer and indirect reduction process mediated by H* were involved in the dechlorination of FLO. The optimal dechlorination efficiency of 98.79% was obtained by Pdx-BTNA cathode within 120 min at 1 mM PdCl2, applied cathode potential of -1.2 V. In addition, Pdx-BTNA exhibited superior stability and durability with almost no Pd leaching (0.0011 mg/L) during five dechlorination cycles. Our research proposed a novel strategy to design low noble Pd-loaded cathode material for efficient dechlorination and detoxification of HOPs.