Degradation pathways and organic matter transformation of acesulfame potassium electro-oxidation in real water matrices

Abstract

Abstract This paper presents the pathways of acesulfame potassium (ACE-K) electro-degradation on a boron-doped diamond (BDD) electrode and the removal/mineralization of ACE-K in different environmental water matrices (biologically treated (hospital) wastewater (BTW), river water (RW), and ground water (GW)). The ACE-K was initially electrochemically transformed to an unknown compound ( m / z = 196) and then organic acids and inorganic compounds before mineralization. In the water matrices, ACE-K was completely degraded (pseudo-first-order apparent rate constants = (1.22‒2.25) × 10 −3 s −1 ). Before electrolysis, all ACE-K spiked solutions showed aromaticity (SUVA 254 ), while during electrolysis the variation of aromaticity was consistent with that of total organic carbon removal. The spike of ACE-K covered or lowered the intensities of fluorescence excitation-emission peaks in humic acid-like, aromatic protein I, and fulvic acid-like regions for BTW and those in soluble microbial by-product-like and tyrosine regions for RW and GW. After 120 min electrolysis, the ACE-K-associated fluorescence peaks disappeared but the original dissolved organic matter (DOM)-related ones slightly remained, so the removal/mineralization was harder for the DOM than for the ACE-K in the tested matrices. Electrolysis or spiking ACE-K increased the Microtox acute toxicity response in BTW.