Electrochemical Hydrogenation of Refractory Organic Pollutants for Wastewater Treatment

Abstract

Wastewater treatment is an essential process for the sustainable development of a society. The handling and degrading of different refractory and toxic organic pollutants heavily relies on conventional biodegradation. Herein, we developed an electrochemical hydrogenation method to enhance the biodegradability of organic substrates, which subsequently improves their availability to existing biological-driven denitrification, a key step that turned NO3 - into harmless N2. The strategy presents an unprecedented "kill-two-birds-with-one-stone" method to simultaneously deal with excessive organic components, aka. Chemical Oxygen Demand (COD), and nitrate's presence in wastewater. The strategy was discovered by comparing the biodegradability of some organic compounds and their hydrogenation forms. It was found that the hydrogenation product was much more bioavailable. Motivated by this discovery, we synthesized a carbon-supported Ru electrode by electrodepositing Ru on activated carbon cloth (ACC), named Ru/ACC. After that, 4-chlorophenol was used to optimize the experimental conditions, and Ru/ACC electrodes successfully converted 99.9% of 4-chlorophenol with an overall yield reached 90.9%. After that, the Ru/ACC electrodes proved efficient in transferring various wastewater organic pollutants. Besides, the electrochemical hydrogenation effect on biochemical degradation and denitrification was studied. Our electrochemical treatment was significant for the electrochemical hydrogenation method to be applied to wastewater treatment.