title: Manipulation of persistent free radicals in biochar to activate persulfate for contaminant degradation.
abstract: This study investigated the effects of metals (Fe3+, Cu2+, Ni2+, and Zn2+) and phenolic compounds (PCs: hydroquinone, catechol, and phenol) loaded on biomass on the formation of persistent free radicals (PFRs) in biochar. It was found that metal and phenolic compound treatments not only increased the concentrations of PFRs in biochar but also changed the types of PFRs formed, which indicated that manipulating the amount of metals and PCs in biomass may be an efficient method to regulate PFRs in biochar. These results provided direct evidence to elucidate the mechanism of PFR formation in biochar. Furthermore, the catalytic ability of biochar toward persulfate activation for the degradation of contaminants was evaluated. The results indicated that biochar activates persulfate to produce sulfate radicals (SO4•-) and degraded polychlorinated biphenyls (PCBs) efficiently. It was found that both the concentration and type of PFRs were the dominant factors controlling the activation of persulfate by biochar and that superoxide radical anions account for 20-30% of sulfate radical generation in biochar/persulfate. This conclusion was supported by linear correlations between the concentration of PFRs consumed and the formation of SO4•- and between λ (λ=[formed sulfate radicals]/[consumed PFRs]) and g-factors. The findings of this study provide new methods to manipulate PFR concentration in biochar for the transformation of contaminants and development of new alternative activators for persulfate-based remediation of contaminated soils.
authors: †Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008 Jiangsu, P. R. China.
authors: Guodong
authors: G
authors: Fang
authors: †Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008 Jiangsu, P. R. China.
authors: Cun
authors: C
authors: Liu
authors: †Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008 Jiangsu, P. R. China.
authors: Juan
authors: J
authors: Gao
authors: §Environmental Engineering and Science Program, University of Cincinnati, Cincinnati, Ohio 45221-0012, United States.
authors: Dionysios D
authors: DD
authors: Dionysiou
authors: †Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008 Jiangsu, P. R. China.
authors: Dongmei
authors: D
authors: Zhou
mesh_terms: D000838:Anions; D002606:Charcoal / Q000737:chemistry*; D004785:Environmental Pollutants / Q000032:analysis*; D052918:Environmental Restoration and Remediation; D005609:Free Radicals / Q000737:chemistry*; D007501:Iron / Q000737:chemistry; D008670:Metals / Q000737:chemistry; D011078:Polychlorinated Biphenyls / Q000737:chemistry; D013431:Sulfates / Q000737:chemistry*; D013481:Superoxides / Q000737:chemistry; D013696:Temperature; D013997:Time Factors
chemical_list: D000838:Anions; D004785:Environmental Pollutants; D005609:Free Radicals; D008670:Metals; D013431:Sulfates; C540010:biochar; D013481:Superoxides; D002606:Charcoal; D011078:Polychlorinated Biphenyls; D007501:Iron