Zirconia-chitosan beads as highly efficient adsorbent for defluoridation of water

Abstract

Zirconia modified chitosan beads (Zr-CTS) have been synthesized as adsorbent for fluoride ions from water bodies. The beads have been characterized using FTIR, SEM, EDX, TG-DTA and BET surface area analysis. Batch adsorption parameters are performed for defluoridation of water using the prepared composite. The pH point of zero charge was found to be 5.7. Maximum efficiency of the adsorbent is observed at pH 4.0, with adsorbent dose of 40 mg per 25 mL of 25 ppm fluoride solution and adsorption period of 45 min. Under these conditions, Zr-CTS is found to have an adsorption capacity of 52.63 mg g^-1 in accordance with Freundlich adsorption isotherm. Thermodynamics parameters reveal that the process of adsorption was spontaneous, exothermic and leading to increase in entropy. The process follows pseudo-second-order kinetics model. The used material is regenerated using 5% NaCl solution and could be reused in multiple cycles adding greener dimension.