Chitosan based radiation crosslinked and grafted matrix: An environment friendly adsorbent for dye uptake

Abstract

The adsorption capacity of [2-(methacryloxy) ethyl] trimethylammonium chloride (MAETC) grafted-crosslinked chitosan (CRChitosan-g-MAETC) using ionizing radiation was evaluated for adsorption of anionic dyes namely Acid Blue-25 (AB25), Reactive Orange-16 (RO16) and Reactive Red-120 (RR120) from manufactured aqueous solutions. Effect of various experimental variables like dye concentration, pH, contact time duration, temperature and adsorption on adsorbent grafted to different extent on adsorption kinetics and on equilibrium adsorption was investigated. To understand the equilibrium adsorption of dyes on the adsorbent the data was fitted into Langmuir, Freundlich and Temkin adsorption isotherms while adsorption kinetics was examined using pseudo-first order, pseudo-second order and intraparticle diffusion kinetic models. It was observed that the adsorption of all the three anionic dyes studied was better explained by the Freundlich model. Adsorption extent of dye varied with number of charge sites on the dye molecule. The adsorption of all the three anionic dyes followed pseudo-second order kinetics. Thermodynamic parameters such as standard enthalpy (ΔHo), standard entropy (ΔSo) and standard free energy (ΔGo) were estimated. The radiation grafted cationic adsorbent showed promising adsorbent properties for removal of anionic dyes.