Removal of nitrate and phosphate ions from aqueous solution using zirconium encapsulated chitosan quaternized beads: Preparation, characterization and mechanistic performance

Abstract

The traditional adsorbents are generally retrieval for reutilizing or direct disposal properties. In this work, a more effective and cost-effective technique is employed for adsorbent materials. Chitosan beads (CS) are recognized to be efficient bio-adsorbent for the remediation of toxic anions from aqueous solutions. In the present study, the zirconium encapsulated chitosan quaternized (Zr@CSQ) beads were prepared and its application for the adsorptive removal of nitrate and phosphate ions from water. The fabricated Zr@CSQ beads were characterized by a sequence of analytical techniques, including XRD, SEM, EDAX, BET, FTIR and TGA–DSC analysis. The different kinetic models and known Langmuir, Freundlich and Dubinin–Radushkevich (D–R) isotherm models were used to define the isotherm and kinetic saturations for toxic anions adsorption using Zr@CSQ beads. The Zr@CSQ beads showed superior adsorption capacity at 80.2 and 67.7 mg/g for nitrate and phosphate ions, respectively. Thermodynamic parameters demonstrated that the sorption process is spontaneous, feasible and exothermic nature. The impact of other influencing co-ions like bicarbonate, chloride and sulphate on the removal efficiency of nitrate and phosphate ions were examined. Toxic anions removal by Zr@CSQ beads were found to occur through the adsorption of nitrate and phosphate ions on the surface of beads via electrostatic attraction, ion exchange, and surface complexation mechanism. The obtained results revealed that the removal efficiency of toxic anions, good adsorption–desorption performance and appropriate form, Zr@CSQ beads considered as a promising adsorbent for water/ wastewater purifications.