Removal of Cr(VI) from aqueous solution using chitosan-g-poly(butyl acrylate)/silica gel nanocomposite

• Synthesis of novel chitosan-g-poly(butyl acrylate)/silica gel nanocomposite for toxic chromium removal.
• Biosorption process follows Langmuir better than Freundlich isotherm model.
• Chelation of metal ion takes place with non-covalent interaction.

The present work deals with the preparation of the novel sorbent, glutaraldehye crosslinked silica gel/chitosan-g-poly(butyl acrylate) (Cs-g-PBA/SG) nanocomposite by sol–gel method for removal of toxic chromium ion. Prepared nanosorbent was then characterized by FTIR, XRD, DLS, SEM, BET isotherm for its formation and suitability. Its sorption capacity and sorption isotherms were brought under batch mode to suit the optimal parameters viz., contact time, pH, adsorbent dose and initial metal ion concentration which influence the sorption. The theoretical modeling such as Langmuir and Freundlich isotherm adsorption were applied to describe isotherm constants. Equilibrium data agreed well with the Langmuir isotherm model (R2 = 0.9763) with maximum adsorption capacity of 55.71 (mg/g). The kinetic studies showed that the adsorption follows the pseudo-second-order kinetics (R2 = 0.9999). From the results, it was concluded that Cs-g-PBA/SG nanocomposite is an excellent biosorbent for Cr removal from wastewater.