Electrocatalytic deep hydrogenation of 4-chlorophenol into cyclohexanol on microchannel-enhanced Ru/TiO2 for wastewater detoxification and simultaneous resource recovery

Abstract

Chlorophenols (CPs) are among the most significant environmental concerns worldwide, which pose a serious threat to global water safety and human health. Herein, a novel electrocatalytic hydrogenation (ECH) pathway was proposed for the detoxification of CPs, where both the cleavage of C−Cl bond and hydrogenation of phenol ring take place. Employing a fibrous Ru/TiO2 electrode (f-Ru/TiO2) with massive microchannels, we achieved over 99.8% removal of 1 mM 4-chlorophenol (4-CP) within 60 min, with a corresponding kinetic constant of 0.101 min−1. The toxic 4-CP was completely transformed into cyclohexanol, which possesses almost no biotoxicity and could be rapidly recovered from treated water. The ECH system exhibited high 4-CP removal efficiencies at different pH conditions (3−11). Besides, a 4-CP removal efficiency of over 99.1% was achieved even at a remarkably high concentration (10 mM). Mechanism analysis confirms that direct electron transfer dominates the ECH process, while the contribution of atomic hydrogen (H*) is less prominent. Overall, this study demonstrates an inspiring ECH approach with enhanced pollutants diffusion and electron transfer for not only the detoxification of but also resource recovery from chlorophenol wastewater.