Removal of phosphate ions from wastewater by treated hydrogel based on chitosan

Abstract

Chitosan/Gelatin/2-(Dimethylamino) ethyl methacrylate (Cs/Gltn/PDMAEMA) hydrogel was synthesized by gamma irradiation for the expulsion of phosphate ions from wastewater. Chemical adjustment of the hydrogel with thiourea was performed to introduce thiol groups Cs/Gltn/PDMAEMA-treated. Moreover trapping of SiO2 into the hydrogel matrix to acquire Cs/Gltn/PDMAEMA/SiO2 composite. It was found that the gelation increases with increasing PDMAEMA content in the hydrogel. The maximum gelation performed at an equal ratio of Cs/Gltn at a radiation dose of 15 kGy. The adsorption capacities of the prepared systems towards phosphate ions were investigated. It was obtained that the maximum removal is achieved at pH 6 through 180 min. However, the removal percent decreases with increasing phosphate ions concentration and temperature. The ability of the prepared adsorbents towards phosphate ions removal are ascending ordered in the sequence of Cs/Gltn/PDMAEMA hydrogel, Cs/Gltn/PDMAEMA-treated, and Cs/Gltn/PDMAEMA/SiO2 composite. The pseudo second-order equation fits well the adsorption kinetics. The adsorption isotherm follows the Freundlich model higher than the Langmuir model.