Enhanced degradation of sweetener acesulfame by fluidized activated coke in a 3D electrochemical oxidation process

Activated coke (ACO) has proven effective in treating secondary effluent. In this study, fluidized ACO was utilized as particle microelectrode to catalyze peroxydisulfate (PDS) in a three-dimensional (3D) electrochemical oxidation (EO) process, referred to as 3D EO/ACO-PDS process, for the treatment of sweetener acesulfame. The pseudo-first-order constant for the EO/ACO-PDS process was found to be 4.08 times that of the total of EO-PDS and ACO processes, indicating a significant synergy between ACO and EO-PDS process. The optimized operational parameters through response surface methodology were ACO dosage of 1.21 g/L, PDS concentration of 0.734 mM, and initial solution pH 3.19, resulting in 99.9 % ACE removal efficiency experimentally. Coexisting chloride and natural organic matter slightly enhanced ACE degradation while NO3− evidently inhibited it. It was found that bulk •OH, interface •OH and SO4•−, O2−•, 1O2 and h+ played crucial roles in acesulfame degradation. The introduction of fluidized ACO shifted the oxidation mechanism from being primarily •OH-based in the EO process to a more complex radical and non-radical mechanism in the EO/ACO-PDS process. Our study shows that the 3D EO/ACO-PDS technology offers a promising solution for industrial wastewater treatment applications.