Activation of peracetic acid with zero-valent iron for tetracycline abatement: The role of Fe(II) complexation with tetracycline

Peracetic acid (PAA) is an excellent oxidant that can produce multiple carbon-centered radicals (R•C). A novel advanced oxidation process (AOP) that combines PAA and nanoscale zero-valent iron (i.e. nZVI/PAA) is constructed to evaluate its performance toward tetracycline (TC) abatement. The nZVI/PAA process shows excellent abatement efficacy for TC in the pH range of 3.5–7.5. The presence of humic acid , HPO 4 2− and HCO 3 − exerts inhibitory effects on TC abatement, while the presence of Cl − displays negligible influence in the nZVI/PAA process. Nanoscale zero-valent iron (nZVI) exhibits excellent reusability with no apparent variation in crystallinity . CH 3 C(O)OO• is the predominant active radical that contributes to TC abatement, in which leakage of Fe(II) from the nZVI surface is crucial for a radical generation. Due to the strong complexation tendency of TC towards Fe(II), the Fe(II)-TC complexes are formed, which significantly accelerates the PAA decomposition and TC abatement compared to free Fe(II). In addition, the degradation intermediates of TC are identified, and a possible degradation pathway is proposed. These results will be useful for the application of PAA-based AOPs in the treatment of water containing organic micropollutants.