Synthesizing a Novel Zr/Fe/Al-Incorporated Cross-linked Chitosan as Absorbent for Effective Removal of Fluoride from Aqueous Solution

Zr/Fe/Al-modified chitosan beads were synthesized as a potential absorbent to remove fluoride on wastewater. In this study, the effects of solution pH, absorbent dosage, initial concentration, adsorption time, and coexisting ions were evaluated through a series of experiments. It was found that an adsorption capacity of 37.49 mg/g was achieved in the conditions with pH at 6.0, 1.6 g/L of the dose of CS-ZFA, 60 mg/L of fluoride concentration, and 120 min adsorption time. The adsorption results indicated that fluoride adsorption by CS-ZFA can be explained by Langmuir isotherm. Moreover, the kinetic studies indicated that the adsorption process was in good compliance with the pseudo-second-order kinetics and intra-particle diffusion model. The newly synthesized absorbents were characterized by SEM, EDS, FTIR, and TG analysis. Based on the characterization, the high adsorption capacity of the newly synthesized absorbent is due to the electrostatic attraction between amino and metal ions and the formation of CS-ZFA complex for fluoride. These excellent adsorption properties revealed that CS-ZFA is an effective absorbent for removing fluoride in aqueous solutions of environmental remediation.