title: Removal of antibiotics from water in the coexistence of suspended particles and natural organic matters using amino-acid-modified-chitosan flocculants: A combined experimental and theoretical study.
abstract: Contamination of trace antibiotics is widely found in surface water sources. This work delineates removal of trace antibiotics (norfloxacin (NOR), sulfadiazine (SDZ) or tylosin (TYL)) from synthetic surface water by flocculation, in the coexistence of inorganic suspended particles (kaolin) and natural organic matter (humic acid, HA). To avoid extra pollution caused by petrochemical products-based modification reagents, environmental-friendly amino-acid-modified-chitosan flocculants, Ctrp and Ctyr, with different functional aromatic-rings structures were employed. Jar tests at various pHs exhibited that, Ctyr, owning phenol groups as electron donors, was favored for elimination of cationic NOR (∼50% removal; optimal pH: 6; optimal dosage: 4mg/L) and TYL (∼60% removal; optimal pH: 7; optimal dosage: 7.5mg/L), due to π-π electron donator-acceptor (EDA) effect and unconventional H-bonds. Differently, Ctrp with indole groups as electron acceptor had better removal rate (∼50%) of SDZ anions (electron donator). According to correlation analysis, the coexisted kaolin and HA played positive roles in antibiotics' removal. Detailed pairwise interactions in molecular level among different components were clarified by spectral analysis and theoretical calculations (density functional theory), which are important for both the structural design of new flocculants aiming at targeted contaminants and understanding the environmental behaviors of antibiotics in water.
authors.affiliation: School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, Nanjing Normal University, Nanjing 210023, PR China.
authors.forename: Shuying
authors.initials: S
authors.lastname: Jia
authors.affiliation: School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, Nanjing Normal University, Nanjing 210023, PR China. Electronic address: yangzhen@njnu.edu.cn.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Yang
authors.affiliation: School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, Nanjing Normal University, Nanjing 210023, PR China.
authors.forename: Kexin
authors.initials: K
authors.lastname: Ren
authors.affiliation: Department of Chemistry, University of California, Riverside, CA 92521, United States.
authors.forename: Ziqi
authors.initials: Z
authors.lastname: Tian
authors.affiliation: School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, Nanjing Normal University, Nanjing 210023, PR China.
authors.forename: Chang
authors.initials: C
authors.lastname: Dong
authors.affiliation: School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, Nanjing Normal University, Nanjing 210023, PR China.
authors.forename: Ruixue
authors.initials: R
authors.lastname: Ma
authors.affiliation: School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, Nanjing Normal University, Nanjing 210023, PR China.
authors.forename: Ge
authors.initials: G
authors.lastname: Yu
authors.affiliation: School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, Nanjing Normal University, Nanjing 210023, PR China. Electronic address: yangwb007@njnu.edu.cn.
authors.forename: Weiben
authors.initials: W
authors.lastname: Yang
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D000900:Anti-Bacterial Agents / Q000032:analysis*; D048271:Chitosan / Q000737:chemistry*; D005427:Flocculation; D006812:Humic Substances / Q000032:analysis*; D007616:Kaolin / Q000032:analysis*; D008962:Models, Theoretical; D010316:Particle Size; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
chemical_list: D000596:Amino Acids; D000900:Anti-Bacterial Agents; D006812:Humic Substances; D014874:Water Pollutants, Chemical; D007616:Kaolin; D048271:Chitosan
keywords: Amino acid-modified-chitosan flocculant; Antibiotics; DFT calculation; Environmental behavior; Surface water