Theoretical studies on the aqueous phase and graphene heterogeneous degradation of acrylamide and acrylonitrile by HO, ClO, and BrO radicals

The newly discovered ClO center dot and BrO center dot contribute to pollutant degradation in advanced oxidation processes, while acrylamide (AM) and acrylonitrile (ACN) are always the focus of scientists concerned due to their continuous production and highly toxic effects. Moreover, various particles with a graphene-like structure are the companions of AM/ACN in dry/wet sedimentation or aqueous phase existence, which play an important role in heterogeneous oxidation. Thus, this work focuses on the reaction mechanism and environmental effect of AM/ ACN with ClO center dot/BrO center dot/HO center dot in the water environment under the influence of graphene (GP). The results show that although the reactivity sequence of AM and ACN takes the order of with HO center dot > with BrO center dot > with ClO center dot, the easiest channel always occurs at the same C-position of the two reactants. The reaction rate constants (k) of AM with three radicals are 2 times larger than that with ACN, and amide groups have a better ability to activate C--C bonds than cyanide groups. The existence of GP can accelerate the target reaction, and the k increased by 9-13 orders of magnitude. The toxicity assessment results show that the toxic effect of most products is lower than that of parent compounds, but the environmental risk of products from ClO center dot/BrO center dot-adducts is higher than those from HO center dot-adducts. The oxidative degradation process based on ClO center dot and BrO center dot deserves special attention, and the catalytic effect of GP and its derivatives on the oxidation process is non-negligible.