A Novel Source of Radicals from UV/Dichloroisocyanurate for Surpassing Abatement of Emerging Contaminants Versus Conventional UV/Chlor(am)ine Processes.

Ultraviolet (UV)/chlor(am)ine processes are emerging advanced oxidation processes (AOPs) for water decontamination and raising continuous attention. However, limitations appear in the UV/hypochlorite and UV/monochloramine for removing specific contaminants ascribed to the differences in the sorts and yields of free radicals. Here, this study reports UV/dichloroisocyanurate (NaDCC) as a novel source of radicals. NaDCC was demonstrated to be a well-balanced compound between hypochlorite and monochloramine, and it had significant UV absorption and a medium intrinsic quantum yield. The UV/NaDCC produced more substantial hydroxyl radicals (·OH) and reactive chlorine species (RCSs, including Cl·, ClO·, and Cl 2 · - ) than conventional UV/chlor(am)ine, thereby generating a higher oxidation efficiency. The reaction mechanisms, environmental applicability, and energy requirements of the UV/NaDCC process for emerging contaminants (ECs) abatement were further investigated. The results showed that ·OH and ·NH 2 attacked ECs mostly through hydrogen atom transfer (HAT) and radical adduct formation, whereas Cl· destroyed ECs mainly through HAT and single electron transfer, with ClO· playing a certain role through HAT. Kinetic model analyses revealed that the UV/NaDCC outperformed the conventional UV/chlor(am)ine in a variety of water matrices with superior degradation efficiency, significantly saving up to 96% electrical energy per order. Overall, this study first demonstrates application prospects of a novel AOP using UV/NaDCC, which can compensate for the deficiency of the conventional UV/chlor(am)ine AOPs.