Sorption Of Tylosin On Nano-TiO₂/HA Complex

With the increasing production and application of nano-materials, more and morenano-materials entered into the water andeffected the aquatic environment. Because therewere a lot of humic substances in environmental water, when it combined with nanomaterialswhich will likely have an impact on the environmental behavior of nanomaterials. Themigration, transformation and ecological effects of nanomaterials in the environment hasbecome a very hot of research field in recent years.In this studies, the commonly used titanium dioxide (TiO2) and macrocyclic esterantibiotics-tylosin (TYL) as a representative were employed to study the adsorption behaviorof TYL on TiO2and he adsorption of TYL on the nanometic/humic axid(HA) complexeswere investigated.(1) TYL can be adsorbed by nano-titanium dioxide and the adsorption equilibrium canbasically reach at8h. The adsorption kinetics meets two kinetic models, which illustrated theadsotption may be controlled by two or more steps. The linear model can be fitted adsorptionand desorption isotherms very well, which indicated the adsorption mechanism may be lineardistribution and hydrophobic interaction.(2) Adsorption of tylosin on titanium dioxide is closely related with the specific surfacearea of titanium dioxide, the isoelectric point and pH value of the solutions. In acidicconditions, negative charge on the titanium dioxide adsorbed positive charge of tylosin with astrong of electrostatic interaction, while in neutral and alkaline conditions, distributionfunction of tylosin uncharged molecular with the surface of the titanium dioxide is the majordeterminant of adsorption of tylosin on titanium dioxide. The adsorption capacity increasedwith pH value increased; As ionic strength increased, sorption of tylosin firstly increased, thenremained relatively reduce. It indicated that the sorption ability of nano-TiO2might beinfluenced by the environment condiations, which effected the transportation andtransformation of antibiotics in aquatic environment.（3）The adsorption was significantly enhanced after adding humic acid, which is due tothe humic acid functional groups in the process of adsorption TYL.The adsorption capacity oftylosin on nano-TiO2with different sources of DOMs complexes is different and thedesorption hysteresis is not obviously. The influence of the ionic strength and pH on tylosinadsorption on the composite is displayed. Ion exchange may be the main factors whicheffected the sorption of tylosin. In addition, hydrogen bonding, hydrophobic, andelectrostatic forces may be also contributed to the sorption of tylosin on complexes.