Comparative study on Pb2+ removal using hydrothermal synthesized β-SrHPO4, Sr3(PO4)2, and Sr5(PO4)3(OH) powders

In this work, β-SrHPO 4 , Sr 3 (PO 4 ) 2 , and Sr 5 (PO 4 ) 3 (OH) (SrHAp) powders were successfully prepared by a controllable hydrothermal method and were utilized in removal of lead ion (Pb 2+ ). The effects of pH value, contact time and initial ion concentration on the immobilization of Pb 2+ were investigated systematically. Results showed that β-SrHPO 4 exhibited a capacity of 1438 ± 45 mg/g for Pb 2+ , while Sr 3 (PO 4 ) 2 and SrHAp showed values of 1223 ± 45 mg/g and 543 ± 45 mg/g respectively under the optimum conditions. The XRD , SEM and EDX results revealed that the mechanism of Pb 2+ immobilization by β-SrHPO 4 , Sr 3 (PO 4 ) 2 and SrHAp was mainly due to a process of dissolution and precipitation in the acidic solution. Comparing the immobilization behavior and capacities of β-SrHPO 4 , Sr 3 (PO 4 ) 2 and SrHAp for Pb 2+ removal, it is shown that β-SrHPO 4 is an effective and eco-friendly material for the removal of Pb 2+ from acidic aqueous solutions among strontium phosphates materials.