Effects of addition of cationic ligands in hydrous bismuth oxide on removal of fluoride from aqueous solutions

Hydrous bismuth oxides (HBO2) have been reported to have anionic sorptive properties. In the present study, removal of fluoride from aqueous solution has been explored for its possible application in drinking water treatment. The performance of fluoride removal from aqueous solutions has been studied by adding four cationic ligands (Fe2+, Mg2+, Ca2+ and Cu2+) in the matrix of hydrous bismuth oxide (HBO2). Enhanced fluoride removals properties were observed by addion of cations in hydrous bismuth oxide as compared to hydrous bismuth oxide alone. The pH of the treated water was remained in the range 6.9-9.1, indicating that OH- ions are not released from the adsorbents during fluoride adsorption. Characterizations of HBO2 and HBO2 with four cationic ligands were achieved by using XRD analyses and the tested powders are found crystalline in nature as they show large and sharp peaks. FTIR analyses of tested materials support the results obtained through XRD analyses. Ca and Mg ions in HBO2 appear to increase the pH of point of zero charge (pHPZC) of the powders.