Degradation of three typical hydroxamic acids collectors via UVA-B activated H2O2 and persulfate: Kinetics, transformation pathway, DFT calculation and toxicity evaluation

•Direct photolysis’ contribution to SHA removal was much higher than that of HO• and SO4•−.•Second-order rate constant of three HAAs with HO• and SO4•− were determined.•At pH 5.0–9.0, the degradation of BHA and NOP were always dominated driven by SO4•−.•DFT calculation was applied to predict the reactive sites and degradation pathways.•Hydrolysis, hydroxylation, decarboxylation and ring opening were the main pathways.