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 center dot 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, HPO42xe213; and HCO3xe213; 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. CH3C(O)OO center dot 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.

Automated summary

Peracetic acid (PAA) is an efficient oxidant that, when combined with nanoscale zero-valent iron, shows promising results in the removal of tetracycline (TC). Factors such as the presence of humic acid, phosphate, and bicarbonate ions can inhibit the removal of TC. Nanoscale zero-valent iron exhibits good reusability and the predominant active radical for TC removal is identified as CH3C(O)OO center dot, generated through Fe (II) leakage. Formation of Fe (II)-TC complexes accelerates PAA decomposition and TC removal.