Biogenic hydroxyapatite (Apatite II™) dissolution kinetics and metal removal from acid mine drainage

Removal of Pb2+, Zn2+, Mn2+ and Cu2+ was by formation of phosphate-metal compounds on the Apatite II™ substrate, whereas removal of Cd2+ was by surface adsorption. Increase in pH enhanced the removal of aqueous heavy metals. Using the kinetic parameters obtained (e.g., dissolution rate and pH-rate dependence law), reactive transport simulations reproduced the experimental variation of pH and concentrations of Ca, P and toxic divalent metal in a column experiment filled with Apatite II™ that was designed to simulate the Apatite II™-metal polluted water interaction.