Lead and copper removal from aqueous solutions by porous glass derived calcium hydroxyapatite

A porous glass was prepared by sintering Na2O–CaO–B2O3 glass powder with powdered sodium chloride. Subsequently, the sodium chloride was dissolved in water resulting in a highly porous material. A sample was prepared consisting of 60 vol% glass and 40 vol% salt which both had particle sizes <100 and 400–500 μm, respectively. The sample was sintered at a temperature of 580 °C for 15 min which resulted in an optimum structure with 57.5% porosity and 0.944 MPa compressive strength. Amorphous calcium hydroxyapatite was formed by immersing these materials in 0.1 M K2HPO4 solutions at room temperature for 1 day. The porous glass derived hydroxyapatite matrix was then processed for removing lead and copper ions from aqueous solutions. The results showed that the glass derived calcium hydroxyapatite matrix effectively immobilizes lead and copper ions in solution. The adsorption mechanism was investigated by the X-ray Diffraction (XRD) and Scanning Electron Microscopy including Energy Dispersive X-Ray Spectrometry (SEM-EDX).

. Adsorption of Pb2+ increases with the increase in NaCl volume percentage (1:0%, 2:30%, 3:40%, 4:40%) of the Glass Derived Hydroxyapatite and reaches equilibrium after 24 h.Figure optionsDownload as PowerPoint slideHighlights
► Novel porous glass derived hydroxyapatite matrix is prepared.
► Glass derived hydroxyapatite matrix adsorbs lead and copper ions in solutions effectively.
► Two adsorption mechanisms including ion exchange theory and the dissolution and precipitation theory are involved in removal of the heavy metal ions from the solutions.