The Study on the Novel Adsorbent Modified Cycledextrin Microspheres to Remove Dyes from Aqueous Solution

The new adsorben pyromellitic dianhydride (PMDA) grafted beta-Cyclodextrin (beta-CD) microspheres were used to remove cationic dyes malachite green (MG) and crystal violet (CV). The different variables affecting the adsorption capacity of the adsorbent such as contact time, initial dye concentration, pH were investigated on a batch sorption basis. The experiments results showed that this adsorbent exhibited high sorption capacities toward MG and CV. The adsorption values increased significantly after a large number of carboxyl groups were gragfted on the microspheres surface. The adsorption kinetics was determined by fitting pseudo-first and second-order kinetic models. The data were better described by the pseudo-second-order model, which confirmed that the sorption rate was controlled by chemical adsorption. The experimental sorption equilibrium data were better fitted by Langmuir(R>0.999) than Freundlich isotherm. The maximum adsorption capacities were 775.19 and 598.8 mg g(-1) for malachite green and methyl vide, respectively.