The formation of trichloronitromethane (TCNM) from natural waters and organic substances in the UV/monochloramine (UV/NH2Cl) process was investigated. Using 15NH2Cl as the nitrogen tracer, we found that 15N-TCNM accounted for more than 70.7% of total TCNM generated from natural waters in the UV/NH2Cl process, highlighting the NH2Cl was the predominant nitrogen source of TCNM rather than the organic nitrogen in natural waters. Additionally, RNS play important roles on formation of the TCNM formation precursor. meta-substituents phenolics and the phenolics containing electron-withdrawing groups facilitated TCNM formation in the UV/NH2Cl process. The TCNM yields in the UV/NH2Cl process were found to be correlated with the Hammett constants (σ). The reactive radicals contributed to the degradation of resorcinol, as a model phenolic compound, and leading to the formation of five nitro(so)-intermediates in the UV/NH2Cl process. The incorporation of reactive nitrogen species with phenolic ring is the key pathways of the formation of TCNM precursors. Increasing pH greatly decreased TCNM yields in the UV/NH2Cl process, which is an effective TCNM control strategy.

UV/monochloramine process ehanced the trichloronitromethane formation: Roles of reactive radicals

ACS Fall 2021

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