Activation of persulfate by Fe(III) species: Implications for 4-tert-butylphenol degradation

In this study the activation of persulfate induced by Fe(III) species, including 5 kinds of iron oxhydroxides (IOs) and dissolved Fe3+ under dark condition were investigated. Ferrihydrite (FH) and akaganeite (AK) showed the highest activity in 4-tert-butylphenol (4tBP) removal. The 4tBP degradation rate constant decreased as the solution pH increased from pH 3.2 to 7.8 in FH/S2O82- system. However, the pH value had no significant effect on the 4tBP degradation in AK/S2O82- system. The degradation of 4tBP in Fe3+/S2O82- system was also performed to investigate the role of ferric species in persulfate activation. The pH dependency of 4tBP degradation rate was closely related to the speciation of Fe-III, whereas the Fe(H2O)(6)(3+) was found to be the most active soluble iron complex form in the activation of S2O82-. 4tBP degradation was mainly due to the SO4 center dot- in IOs/S2O82- system, while SO4 center dot- and HO2 center dot both had great contribution on 4tBP degradation in Fe3+/S2O82- system. Further investigations showed clearly that 4tBP degradation efficiency was decreased significantly due to the trapping of SO4 center dot- by chloride. This finding may have promising implications in developing a new technology for the treatment of contaminated waters and soils, especially where Fe3+ species are naturally occurring. (C) 2016 Elsevier B.V. All rights reserved.