title: Sorption of tylosin and sulfamethazine on solid humic acid.
abstract: Tylosin (TYL) and sulfamethazine (SMT) are ionizable and polar antimicrobial compounds, which have seeped into the environment in substantial amounts via fertilizing land with manure or sewage. Sorption of TYL and SMT onto humic acid (HA) may affect their environmental fate. In this study, the sorption of TYL and SMT on HA at different conditions (pH, ionic strength) was investigated. All sorption isotherms fitted well to the Henry and Freundlich models and they were highly nonlinear with values of n between 0.5 and 0.8, which suggested that the HA had high heterogeneity. The sorption of TYL and SMT on HA decreased with increasing pH (2.0-7.5), implying that the primary sorption mechanism could be due to cation exchange interactions between TYL(+)/SMT(+) species and the functional groups of HA. Increasing ionic strength resulted in a considerable reduction in the Kd values of TYL and SMT, hinting that interactions between H bonds and π-π EDA might be an important factor in the sorption of TYL and SMT on HA. Results of Fourier transform infrared (FT-IR) and (13)C-nuclear magnetic resonance (NMR) analysis further demonstrated that carboxyl groups and O-alkyl structures in the HA could interact with TYL and SMT via ionic interactions and H bonds, respectively. Overall, this work gives new insights into the mechanisms of sorption of TYL and SMT on HA and hence aids us in assessing the environmental risk of TYL and SMT under diverse conditions.
authors.affiliation: School of Earth and Environment, Anhui University of Science and Technology, Huainan 232001, China.
authors.forename: Xuetao
authors.initials: X
authors.lastname: Guo
authors.affiliation: School of Earth and Environment, Anhui University of Science and Technology, Huainan 232001, China.
authors.forename: Bei
authors.initials: B
authors.lastname: Tu
authors.affiliation: School of Earth and Environment, Anhui University of Science and Technology, Huainan 232001, China.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Ge
authors.affiliation: College of Environment and Energy, South China University of Technology, Guangzhou 510006, China. Electronic address: cyanggz@scut.edu.cn.
authors.forename: Chen
authors.initials: C
authors.lastname: Yang
authors.affiliation: School of Earth and Environment, Anhui University of Science and Technology, Huainan 232001, China.
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Song
authors.affiliation: College of Environment and Energy, South China University of Technology, Guangzhou 510006, China.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Dang
mesh_terms: D000327:Adsorption; D000900:Anti-Bacterial Agents / Q000737:chemistry*; D006812:Humic Substances; D006863:Hydrogen-Ion Concentration; D008956:Models, Chemical; D009994:Osmolar Concentration; D013418:Sulfamethazine / Q000737:chemistry*; D015645:Tylosin / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D006812:Humic Substances; D013418:Sulfamethazine; D015645:Tylosin
keywords: Antibiotics; Cation exchange; Humic acid; Sorption