Direct ultraviolet (UV) irradiation and UV-based advanced oxidation processes (AOPs) containing UV/hydrogen peroxide (UV/H2O2) and UV/persulfate (UV/PS) systems have been diffusely practiced for the attenuation of contaminations. However, with the addition of different anions, the degradation pathway and overall toxicity of these reaction systems are still debated. The chloroxylenol (PCMX) was chosen as our model pollutant for a full assessment of direct UV irradiation and the UV-based AOPs in this work. The density functional theory method was employed for the interpretation of reactive sites of contamination. As for the PCMX decontamination in the UV-based systems, the addition of Cl–, NO3–, CO32–, and HCO3– could instigate a dual consequence. Besides, the degradation intermediates in direct UV irradiation, UV/PS, and UV/H2O2 systems were quite distinct especially in the presence of various anions. The Quantitative Structure Activity Relationship method of Ecological Structure Activity Relationships predictive model was then utilized to estimate the short- and long-time toxicity of PCMX and byproducts. Finally, the semi-quantitative toxicity evaluation method was proposed based on the mixture toxicity index theory, and the results indicated that the overall toxicity of the UV/H2O2 system was lower than that of others, especially when NO3– were present. This research would be meaningful for the systematic evaluation of UV-based remediation processes.

Nonignorable involvement of water matrix: Reevaluation on degradation pathways and toxicity evolution of UV-based AOPs for chloroxylenol decontamination

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ACS Fall 2022

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