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

Abstract

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 wellbalanced 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.

A High-Radical-Yield Advanced Oxidation Process Coupling Far-UVC Radiation with Chlorinated Cyanurates for Micropollutant Degradation in Water

“…Sodium dichloroisocyanurate (NaCl 2 Cy) is a solid form of chlorine that is widely used in treating both swimming pool water and drinking water in many countries (e.g., the United States and New Zealand). − It is simpler to handle than liquid and gaseous forms of chlorine and can be stored for years . NaCl 2 Cy is stable under solar light because of the minimum absorption at wavelengths longer than 290 nm .…”

Graphitic N-Rich Graphene for Nonradical Peroxymonosulfate Activation

“…During the past decades, heavy metals and microbial and organic pollutants have been recognized as main threats to water quality, putting a huge burden on the sustainability of our society. − In comparison with other pollutants, organic pollutants possess the features of structural diversity, environmental stability, bioaccumulation, and long-lasting toxicity, which have drawn great research interest. − To remove organic pollutants from water bodies, peroxymonosulfate (PMS)-based advanced oxidation processes have shown the greatest potential because it can effectively generate reactive oxidant species (ROS) to oxidize organic pollutants. , Commonly, PMS can be activated by thermal heating, UV-lighting, ultrasound, transition metals, or nanocarbons . Among these methods, the metal-free nanocarbons are highly efficient, of low cost, and environmentally friendly, without the requirement of external energy input and special equipment during PMS activation.…”

The degradation of ciprofloxacin in the UV/NH2Cl process: kinetics, mechanism, pathways and DBP formation

“…7,8 AOPs based on ultraviolet treatment, such as UV/persulfate, UV/H 2 O 2 , UV/chlorine, and UV/NH 2 Cl, have developed rapidly in the past two decades and are being widely used in water pollution treatment. 9,10 Among them, NH 2 Cl as a long-lasting disinfectant may decrease the formation of DBPs due to its low reactivity compared to chlorine 11 and it could be as a possible alternative disinfectant for chlorine recommended by the World Health Organization (WHO). 12 The UV/NH 2 Cl oxidation process has a better effect than UV/H 2 O 2 in water pollution treatment, and there is no need to remove the excess H 2 O 2 generated in the process, which reduces the cost.…”