Abstract
Porous hydroxyapatite (HAp) monoliths synthesized from gypsum mold waste were used for removing lead ions from aqueous solution. The gypsum waste was crushed into small blocks and converted directly to porous HAp pieces in a 0.5mol/dm3 diammonium hydrogen phosphate solution at 55 and 80°C. Porous structures were effected by reaction temperatures. Twenty and 40mg of lead ions were removed from 100cm3 aqueous solution by stirring with 1.0g porous HAp monoliths at pH 3 for 5 to 30min. HAp was dissolved in the pH 3 acidic solution, but Pb-Cl apatite, which was formed from Pb2+, PO43- and Cl-, was stable in the pH 3 acidic solution.
