Factors controlling adsorption of tetracycline antibiotics onto graphene oxide nanoparticles
In this study,adsorption kinetics and adsorption isotherms were employed to investigate the adsorption of tetracycline antibiotics(tetracycline(TC),oxytetracycline(OTC),and chlortetracycline(CTC))onto graphene oxide(GO)nanoparticles.The results of adsorption kinetics demonstrated that the data were fitted well by the pseudo-second-order kinetic models,which indicated that the adsorption rate was probably controlled by chemisorption.Meanwhile,the results obtained by the adsorption isotherm experiments showed that GO exhibited high adsorption capacity for all the three tetracycline antibiotics,and the adsorption capacity followed the order of CTC＞OTC＞TC.The main mechanisms involved in the adsorption behaviors were π-π interaction,cation-π bonding,hydrophobic effect,and electrostatic interaction.Furthermore,the adsorption characteristics were related to solution chemistry conditions such as pH,ionic strength and divalent metal ions.The adsorption capacities of tetracycline on GO decreased with the increasing pH or ionic strength(i.e.,NaCl concentration),which was stemmed from the reduction in electrostatic attraction and the increased electrostatic repulsion between tetracycline antibiotics and GO.Additionally,the presence of divalent cations(i.e.,Cu2+)could significantly promote the adsorption of tetracycline antibiotics due to the surface-bridging mechanism.Our observations indicate that properties of tetracycline antibiotics and solution chemistries play important roles in the removal of tetracycline antibiotics from aqueous solutions by GO nanoparticles.
NETL
NSTL
万方数据
