title: Formation of environmentally persistent free radicals as the mechanism for reduced catechol degradation on hematite-silica surface under UV irradiation.
abstract: Iron is rich in soils, and is recently reported to form stable complexes with organic free radicals, generating environmentally persistent free radicals (EPFRs). The observation may challenge the common viewpoint that iron is an effective catalyst to facilitate the degradation of various organic chemicals. But no study was specifically designed to investigate the possible inhibited degradation of organic chemicals because of the formation of EPFRs in dry environment. We observed that catechol degradation under UV irradiation was decreased over 20% in silica particles coated with 1% hematite in comparison to uncoated silica particles. Stabilized semiquinone or quinine and phenol radicals were involved in HMT-silica system. EPFR formation was thus the reason for the reduced catechol degradation on HMT-silica surface under UV irradiation at ambient temperature. EPFRs should be incorporated in the studies of organic contaminants geochemical behavior, and will be a new input in their environmental fate modeling.
authors.affiliation: Faculty of Environmental Science & Engineering, Kunming University of Science & Technology, Kunming 650500, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Li
authors.affiliation: Faculty of Environmental Science & Engineering, Kunming University of Science & Technology, Kunming 650500, China. Electronic address: panbocai@gmail.com.
authors.forename: Bo
authors.initials: B
authors.lastname: Pan
authors.affiliation: Faculty of Environmental Science & Engineering, Kunming University of Science & Technology, Kunming 650500, China.
authors.forename: Shaohua
authors.initials: S
authors.lastname: Liao
authors.affiliation: Faculty of Environmental Science & Engineering, Kunming University of Science & Technology, Kunming 650500, China.
authors.forename: Di
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, USA.
authors.forename: Baoshan
authors.initials: B
authors.lastname: Xing
mesh_terms: D002396:Catechols / Q000032:analysis / Q000737:chemistry*; D004777:Environment; D005290:Ferric Compounds / Q000737:chemistry*; D005609:Free Radicals / Q000737:chemistry*; D007501:Iron / Q000737:chemistry; D008956:Models, Chemical; D055668:Photochemical Processes; D012822:Silicon Dioxide / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D002396:Catechols; D005290:Ferric Compounds; D005609:Free Radicals; D012987:Soil; C000499:ferric oxide; D012822:Silicon Dioxide; D007501:Iron; C034221:catechol
keywords: Anthropogenic pollutants; Environmental fate; Fate modeling; Iron oxides; Stabilized radicals