Insights on the degradation mechanism of neotame using UV/periodate: Roles of reactive species, kinetics, and pathways

Abstract

As a new artificial sweetener (ASs), the jeopardize of neotame (NEO) to aquatic environment is attracting concern due to its widespread usage and difficulty in removing from wastewater. UV/periodate (UV/PI) is being considered as an effective process for the degradation of micropollutants in wastewater. However, there are few studies of the roles of reactive species (RS) and the effects of complex water matrices on the degradation of NEO via UV/PI. The degradation of NEO in aqueous media by UV/PI was investigated herein. NEO was effectively removed (>97 %) by UV/PI within 4 min. The degradation of NEO was mainly attributed to •OH (75.7 %), IO3• (23.0 %) and 1O2 (1.3 %) with the observed second-order rate constants of 7.71 × 109, 1.56 × 108 and 2.94 × 105 M−1 s−1, respectively. The contribution of IO3• and 1O2 to NEO degradation was greater at acidic and high PI concentrations, but significantly decreased in the presence of natural organic matter. The presence of anions in the water did not obviously impact NEO degradation. During the degradation of NEO, •OH attacked NEO through hydroxylation reaction, while IO3• and 1O2 predominantly participated in decarboxylation and amide hydrolysis reactions. Toxicity evaluation showed that the UV/PI treatment of NEO enhanced the toxicity to Vibrio fischeri within 5 min, and the toxicity reduced with the prolongation of treatment time. The study provides meaningful information on the roles of IO3• and 1O2 for NEO degradation by UV/PI.