Revealing the characteristics of coagulant and ·OH generation in the electrocoagulation coupled with E-peroxone process and comparison of the synergistic effect for water purification

Abstract

Electrocoagulation (EC) coupled with E-peroxone process (ECP) offers a promising approach for simultaneous coagulation and oxidation, enhancing contaminant removal efficiency and current efficiency within a single electrochemical system. However, understanding the production characteristics of active species and their synergistic effects remains limited. This study comprehensively investigated the production of active species (i.e., ·OH and coagulant) during the ECP process and explored their synergistic effect in real water purification. Increasing current density and O3 dosage led to significant enhancements in ·OH and Alb production. The synergistic factor (β) for ·OH production ranged from 1.68 to 1.73 for lower current density and from 1.19 to 1.32 for higher current density, while β for ·OH production in ECP increased from 0.77 to 1.16–1.19 with increased O3 dosage. Besides O3 decomposition and cathodically-induced H2O2 production, alternative pathways contributed to enhanced ·OH production and synergistic effects. The Al-based coagulant facilitated the reaction with O3, initiating a chain reaction for ·OH and Alb production. Furthermore, the feasibility and synergistic effects of ECP for two water matrices (surface water and shale gas produced water) were compared. ECP exhibited superior performance for both matrices, with TOC removal exceeding 63.2 % for surface water and 87.0 % for shale gas produced water. The study provides deeper insights into the ECP process, highlighting its potential for sustainable water treatment.