title: Sorption of aromatic hydrocarbons onto montmorillonite as affected by norfloxacin.
abstract: Effect of norfloxacin (Nor) on the sorption of 1,3-dinitrobenzene (1,3-DNB), and PAHs (naphthalene (NAPH), phenanthrene (PHEN) and pyrene (PYR)) to K(+)-montmorillonite was studied. Nor suppressed 1,3-DNB sorption due to their competition for the same sorption sites. 1,3-DNB was sorbed on K(+)-montmorillonite surface via cation-polar interaction and n-π electron donor-acceptor interaction. Nor also was sorbed on these sites through cation exchange, cation bridging and/or surface complexation. Nor increased three PAHs sorption on montmorillonite and the enhanced magnitude was positively correlated with the π-donor strength of three PAHs. The enhanced sorption of PAHs by Nor was primarily attributed to π-π interaction between π-electron-depleted quinoline ring of Nor and π-electron-rich PAHs. Compared with cation (Nor(+)) and anion (Nor(-)), zwitterion (Nor(±)) of Nor increased PHEN and PYR sorption more pronounced due to additional cation-π interaction between the sorbed Nor(±) and PAHs. (1)H NMR spectrum provided direct evidence for π-π and cation-π complexation between PAHs and Nor(+) in solution by ring-current-induced upfield chemical shifts of amino group and methylene group of Nor(+).
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, PO Box 2871, Beijing 100085, China. peizg@rcees.ac.cn
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Pei
authors.forename: Jingjing
authors.initials: J
authors.lastname: Kong
authors.forename: Xiao-quan
authors.initials: XQ
authors.lastname: Shan
authors.forename: Bei
authors.initials: B
authors.lastname: Wen
mesh_terms: D000327:Adsorption; D000900:Anti-Bacterial Agents / Q000737:chemistry*; D001546:Bentonite / Q000737:chemistry*; D006838:Hydrocarbons / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D009643:Norfloxacin / Q000737:chemistry*; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D000900:Anti-Bacterial Agents; D006838:Hydrocarbons; D001546:Bentonite; D009643:Norfloxacin