Degradation of pyrene in contaminated water and soil by Fe2+-activated persulfate oxidation: Performance, kinetics, and background electrolytes (Cl-, HCO3- and humic acid) effects

Abstract

SO4−-based oxidation technologies have been considered as key solution in polycyclic aromatic hydrocarbons (PAHs) degradation. This study constructed Fe2+-activated persulfate oxidation to degrade pyrene in water and soil by using batch and column experiments. Pyrene degradation kinetic in polluted water and effects of soil background electrolytes (Cl−, HCO3− and humic acid) on pyrene degradation were both investigated. The variation of soil properties during pyrene degradation in soil was evaluated. Polluted water remediation results showed that approximately 93.2 % of pyrene was degraded by 65 mM of persulfate with Fe2+/persulfate molar ratio of 0.25. In soil, 88.5 % of pyrene was degraded under the same persulfate concentration and Fe2+/persulfate molar ratio, and there was a slight decrease of soil pH (from 6.7 to 5.4). Cl−, HCO3− and humic acid in soil brought an adverse effect to pyrene degradation through scavenging SO4−. Column study of soil remediation proved the superiority of Fe2+ in activating persulfate, whose application in soil remediation can finally reduce soil pollution and simultaneously avoid the excessive soil acidification in in-situ remediation. In addition, by evaluating the soil organic matter and total organic carbon during the remediation process, it was found that the soil properties have been improved. Therefore, Fe2+-activated persulfate oxidation would be a feasible way to remediate pyrene polluted water/soil.