Removal of benzo(a)pyrene in polluted aqueous solution and soil using persulfate activated by corn straw biochar

An activator, corn straw biochar, was produced and applied in persulfate-based oxidation to remove benzo(a)pyrene (BaP) in polluted aqueous solution and soil. Polluted aqueous solution remediation results showed that at pH 7, approximately 88.4% of BaP was removed by 10 mM of persulfate activated by 1.6 g/L of biochar, and degradation played a dominant role. Polluted soil remediation results demonstrated that the activated persulfate solution (at 9 g/L) by biochar (at 3 wt% of soil) can remove 93.2% of BaP. In remediation of BaP-polluted soil, increasing biochar dosage and persulfate concentration accelerated BaP degradation to some extent, while excessive biochar or persulfate inhibited the degradation of BaP probably due to the unnecessary SO₄^- consumption. The biochar-activated persulfate oxidation reflected a good performance in tolerating the influences of background electrolytes (such as HCO₃^-, Cl^-, and humic acid (HA)) in soil on BaP remediation. In addition, in the removal of BaP by the oxidation systems activated by biochar, persulfate was proved as a superior oxidant compared to peroxymonosulfate and H₂O₂, and the removal efficiencies of BaP were 93.2%, 86.5%, and 84.4% under the same treatment condition. To sum up, the biochar-activated persulfate oxidation would be a potential application in remediation of BaP-polluted aqueous solution and soil.