Removal of lead ions using phosphorylated alginic acid gel and beads

The hydroxyl groups of alginic acid were modified into phosphate groups to increase the uptake capacity of heavy metals. The phosphorylated alginic acid prepared through chemical reaction with a mixture of H3PO4 and NaH2PO4 showed a high uptake capacity of ca. 2.95 mmol Pb/g-dry resin at pH 4. The increased number of phosphate groups was confirmed by analyzing the content of phosphate through molybdophosphoric acid formation. The phosphorylated alginic acid was successfully immobilized through the PVA-Boric acid method using glutaraldehyde to reduce the hydration of the immobilized beads. When the phosphorylated alginic acid bead was applied to the process, the breakthrough point for lead ions appeared at ca. 700 bed volumes and it showed a high selectivity toward alkaline metals, such as calcium and magnesium ions.