Porous zirconium alginate beads adsorbent for fluoride adsorption from aqueous solutions

Abstract

Porous zirconium alginate beads as a novel adsorbent were prepared for fluoride removal and characterized by SEM, FTIR, TG, EDX and XPS. The effect of solution pH, adsorbent dose, initial fluoride concentration, contact time, medium temperature and the coexisting ions on adsorption capacity of fluoride ion has been studied. The presence of HCO₃⁻, SO₄²⁻ and PO₄³⁻ had a large negative impact on fluoride removal. The kinetics of fluoride ion adsorption onto porous zirconium alginate was followed the pseudo-second-order with correlation of 0.9953. The isotherm data were well fitted to the Langmuir isotherm model and the maximum capacity was 32.797 mg g⁻¹. The values of ΔH⁰, ΔS⁰ and ΔG⁰ were calculated and the results indicated that the process of fluoride adsorption was exothermic and spontaneous. The comparison between porous zirconium alginate and other adsorbents suggested that porous zirconium alginate beads possessed a potential for fluoride removal.