The removal of heavy metals from aqueous solution by utilizing modified β-cyclodextrin microspheres

摘要

Batch adsorption experiments were carried out to remove heavy metals Cu(II)and Ni(II) by pyromellitic dianhydride (PMDA) grafted β-Cyclodextrin (β-CD).The effects concerning the pH of the solution,contact time and initial heavy metal concentration were studied and discussed.The adsorption values increased significantly after a large number of carboxyl groups were gragfted on the microspheres surface.In order to investigate the mechanism of sorption,adsorption data were modeled using the pseudo-first-order and pseudo-second-order kinetic equation.It was found that kinetic studies showed good correlation coefficients for a pseudo-second-order kinetic model,confirming that the sorption rate was controlled by chemical adsorption.The equilibrium process was better described by the Langmuir isotherm than the Freundlich isotherm.XPS analysis further confirmed that the carboxyl group which grafted on the surface of the β-CD microspheres play a very important role in the removal of heavy metals.