Synthesis of a novel adsorbent, hydrous bismuth oxide (HBO2) for the removal of fluoride from aqueous solutions

Hydrous bismuth oxides (HBOs) have been reported to have sorptive capacity to remove anions from water. We have synthesized three HBO adsorbents. The designations of all HBO media (HBO1, HBO2, and HBO3) are based on the increasing concentrations of hydroxides. Present study has been devoted to explore the potential of HBO for the removal of fluoride from aqueous solutions. The removal of fluoride increased by increasing the temperature. The kinetics of removal of fluoride was governed by intraparticle diffusion. From the Dubinin–Radushkevich (D–R) isotherm model, the values of mean adsorption energy (E) were calculated and found below 8 KJ mol−1 which is an indication of physical adsorption of fluoride on HBO2. Out of the competitive anions viz. bicarbonate, chloride, and sulfate, presence of chloride in solution has much effect on fluoride removal by HBO2 adsorbent.