Degradation evaluation of acrylamide in advanced oxidation processes based on theoretical method: Mechanisms, kinetics, toxicity evaluation and the role of soil particles

Acrylamide (AA) is now recognized as an imminent hazardous chemical in the aqueous environment, causing a potential threat to human health. As a neo-formed contaminant (NFC), the degradation measure of AA is largely lacking. In this work, we used quantum chemistry and experimental methods to identify the main degradation mechanism of AA in the UV/H2O2 advanced oxidation process (AOP) for the first time. Radical addition reactions dominate the •OH-initiated AA reaction, resulting in few toxic nitrosamines formation. The interaction between AA and the surface model of soil particles (SixOy(OH)z) is weak, and AA can rapidly migrate down to groundwater via seepage. However, the total rate constants of AA and COMADS2-AA with •OH are 2.75 × 109 and 2.09 × 109 M-1 s-1, and the removal of AA from aqueous and heterogeneous systems reaches 62.30% and 62.05% within 2 h. Whether in the aqueous-phase or on the surface of soil particles, •OH initiated AA reaction is an efficient way to remove AA. Furthermore, the toxicity of the main by-products of AA show less harmful to three aquatic organisms and rats than AA. UV/H2O2 AOP is evaluated as an efficient method to degrade AA while decreasing harm.