title: Co-sorption of ofloxacin and Cu(II) in soils before and after organic matter removal.
abstract: Various mechanisms play roles simultaneously for antibiotic sorption on solid particles. Previous studies simply emphasized mechanisms that match the increased or decreased antibiotic sorption by metal ions, without a general concept including these diverse mechanisms in their co-sorption. We observed both increased and decreased OFL and Cu(II) sorption in their co-sorption system. The comparison of the sorption coefficients of primary adsorbate (Kd(pri)) and co-adsorbate (Kd(co)) suggested that enhanced sorption occurred at high Kd(pri) region (low primary adsorbate concentration). Competitive sorption was observed when Kd(pri) was decreased to a certain value depending on solid particle properties. We thus summarized that if the adsorbates were introduced with low concentrations, OFL (such as hydrophobic region in solid particles) and Cu(II) (such as inner-sphere complexation sites) occupied their unique high-energy sorption sites. Cu(II) complexed with the adsorbed OFL, and OFL bridged by the adsorbed Cu(II) promoted the sorption for both chemicals. With the increased concentrations, the adsorbates spread to some common sorption sites with low sorption energy, such as cation exchange and electrostatic attraction region. The overlapping of Cu(II) and OFL on these sorption sites resulted in competitive sorption at high concentrations. The previously reported apparently increased or decreased sorption in antibiotic-metal ion co-sorption system may be only a part of the whole picture. Extended study on the turning point of decreased and increased sorption relating to water chemistry conditions and solid particle properties will provide more useful information to predict antibiotic-metal ion co-sorption.
authors.affiliation: Faculty of Environmental Science & Engineering, Kunming University of Science & Technology, Kunming 650500, China.
authors.forename: Di
authors.initials: D
authors.lastname: Wu
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.
authors.forename: Shaohua
authors.initials: S
authors.lastname: Liao
authors.affiliation: College of Environmental Science and Engineering, Southwest Forestry University, Kunming 650224, China.
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Sun
authors.affiliation: Faculty of Environmental Science & Engineering, Kunming University of Science & Technology, Kunming 650500, China.
authors.forename: Hongbo
authors.initials: H
authors.lastname: Peng
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: 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
mesh_terms: D000327:Adsorption; D000900:Anti-Bacterial Agents / Q000032:analysis / Q000737:chemistry; D003300:Copper / Q000032:analysis / Q000737:chemistry*; D052918:Environmental Restoration and Remediation; D057927:Hydrophobic and Hydrophilic Interactions; D008956:Models, Chemical; D015242:Ofloxacin / Q000032:analysis / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D012987:Soil; D012989:Soil Pollutants; D003300:Copper; D015242:Ofloxacin
keywords: Binary sorption; Cation bridge; Competitive sorption; Complementary sorption; Complexation