Effect Of Typical Heavy Metals On Sorption Of Norfloxacin And Lindane To Solid Materials In Natural Water

Norfloxacin(NOR)is a antibiotics in quinolone antibiotics and lindane is one of the pesticides in organochlorine pesticides,which are treated as emerging organic pollutants and raditional organic pollutants in the field of environmental science and technology,respectively.The study of environmental characteristics of NOR and lindane in natural water environment has been one of the hot spots to researchers.Sorption process is an important way for organic pollutants to migrate and transform in natural water and affect other processes such as decomposition,evaporation and bioaccumulation of organic pollutants in the environment.In natural water environment,sediments,biofilms and suspended particles are typical solid materials,which affect the migration and transformation of organic pollutants in water by sorption process.In addition,contaminated natural water bodies usually contain a variety of pollutants,such as heavy metals and organic pollutants.The role of coexisting pollutants and multi-phase media in water and their mutual influence are of great significance to understand the migration and transformation of pollutants in real water environment.This paper was mainly studing the effects of Pb(II),Cd(II)cation and Cr(VI),As(V)acid anions,usually existed in natural water,on the sorption of NOR and lindane to sediments,biofilms and suspended particles.The effects of fixed concentrations and concentration change of heavy metals on the sorption of NOR and lindane were studied and analyzed the different effects.The mechanism of effects of heavy metals on the sorption of NOR and lindane to solid materials were analyzed by calculating morphological heavy metals in the sorption system and analysing the variation of composition and structure signatures of dissolved organic matter(DOM)from the solid materials by Ultraviolet-visible and three-dimensional fluorescence spectroscopy.The results indicated that Pb(II),Cd(II),Cr(VI)and As(V)inhibited the sorption of NOR on the sediments and suspended particles,while the sorption of NOR on the biofilms showed an overall trend of promotion.Pb(II)and Cd(II)cations directly competed with NORH2+ for cationic sorption sites on the surface of the solid materials was the main reason for the Pb(II)and Cd(II)inhibited the sorption of NOR on the high cationic capacity of sediments and suspended particles.The Pb(II)and Cd(II)cations flocculated the DOM,interacted with NOR through the electrostatic interaction,in the solution on the surface of the biofilms by cation bridging,which was the main reason for the Pb(II)and Cd(II)promoted the sorption of NOR on the highest content of DOM of biofilms.Cr(VI)and As(V)combined with NORH2+ by static electricity to reduce the positive charge of NOR,and Cr(VI)and As(V)reduced the flocculation of DOM in the solution by electrostatic repulsion with DOM or surface of solid materials,so that norfloxacin bound to DOM was still presented in the solution,these were the main reason for the Cr(VI)and As(V)inhibited the sorption of NOR to sediments and suspended particles.Cr(VI)and As(V)make the surface morphology of solid materials become loose and the hydrophilicity was enhanced by the action of electrostatic repulsion,which was the main reason for the Cr(VI)and As(V)promoted the sorption of NOR containing hydrophilic group on the biofilms.The presence of Pb(II)and Cd(II)overall promoted the sorption of lindane to the three solid materials,while Cr(VI)and As(V)generally inhibited the sorption of lindane by three solid materials.The Pb(II)and Cd(II)cations flocculated the DOM on the surface of the solids by cation bridging and blocking effect of hea vy metal hydration film when Pb(II)and Cd(II)bind to solids surface both enhanced the hydrophobicity of the solid surface,which were the main reason for the Pb(II)and Cd(II)promoted the sorption of lindane to three solid materials.Cr(VI)and As(V)make the surface morphology of solid materials become loose and the hydrophobicity was weakened by the action of electrostatic repulsion with the negatively charged solids surface,which were the main reason for the Cr(VI)and As(V)inhibited the sorption of lindane to three solid materials.Heavy metal cations and acid anions can affect the sorption of ionizable organic compounds by competitive sorption and electrostatic interactions,while affect the sorption of hydrophobic organic compounds by changing the hydrophobicity of solid surface from electrostatic interaction and cation bridging.