Novel vacuum ultraviolet/dichloroisocyanurate process for efficient oxidation of organic pollutants in water: Degradation, detoxification, and mechanism

Vacuum ultraviolet (VUV) can split water in situ to generate reactive species and activate oxidant to promote radical production, benefiting the rapid degradation of organic pollutants. Herein, VUV was used to activate dichloroisocyanurate (DCCNa, an emerging oxidant) to construct novel VUV/DCCNa process for the first time. VUV/DCCNa achieved 99.67% removal of carbamazepine (CBZ) within 5 min and its kinetic constant (1.19 min −1 ) was 1.83–6.61 times that of UV/DCCNa and VUV. With a synergy factor of 1.44, VUV/DCCNa saved energy consumption by 46.58%–83.99%. Influence mechanisms of DCCNa dose and solution pH on VUV/DCCNa process were analyzed. Hydroxyl radical, chlorine radical, and oxychlorine radical were identified as major radicals in VUV/DCCNa for CBZ degradation, with contribution ratios of 74.78%, 15.12%, and 6.72% respectively, and their concentrations were quantified. Besides, degradation pathways of CBZ were recommended via theoretical calculation and determination of intermediates, mainly including deamidation, heterocyclic ring opening, and heterocyclic oxidation recombination. Synergistic reaction mechanisms of VUV/DCCNa were elaborated. Moreover, theoretical calculations and algal growth were used to evaluate the detoxification effect of VUV/DCCNa. Furthermore, water matrices of environmental concentration did not interfere with CBZ removal obviously. Novel VUV/DCCNa process could effectively degrade multiple organics and showed promising prospects in actual waters.