Synthesis and Characterization of Alumina Impregnated Alginate Beads for Fluoride Removal from Potable Water

摘要

The present study was conducted to study the feasibility of alumina impregnated calcium alginate beads to sorb the excess fluoride ions from the potable water. Numerous defluoridation techniques have been explored to remove excess fluoride ions from potable water, no single method has been found to be both effective and inexpensive enough to implement widely. During this work defluoridation was done using alumina impregnated calcium alginate beads without disturbing the drinking water qualities. The optimal condition for synthesis of calcium alginate alumina (Cal-Alg-Alu) beads is 2 % (wt/vol) having 22 % (wt/vol) alumina loading, stirring time: 1 h, drying temperature: 60 ℃ for 8 h. The nature and morphology of pure and fluoride-sorbed calcium alginate alumina beads were characterized by scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX), and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) analysis. The results of batch sorption experiments suggest that Cal-Alg-Alu beads is very effective for defluoridation in the pH range of 3.5-9.0 and sorption is more than 99.9 % in the concentration range of 1-100 mg l~(-1). Equilibrium sorption follows Langmuir isotherms well and the maximum fluoride uptake calculated is 17.0 mg g~(-1). The sorption kinetics can be explained by pseudo-second-order model well and the time needed for equilibrium is 300 min.