SYNTHESIS OF NANO-APATITE CRYSTALS ON THE SURFACE OF PHILLIPSITE

Abstract

Ca-type phillipsite (PHI) synthesized from natural zeolite was covered with the needle-like scaly nano-apatite crystals by a hydrothermal treatment at 80°C for 8h under autogenous pressure. The crystal structure of PHI was not destroyed but the surface morphology was only changed by the formation of hydroxyapatite (HA) with 100×30 nm in size. The HA nano-crystals were grown in a reaction between Ca ions discharged from the nano-channels and cavities of PHI and phosphate ions in (NH₄)₃PO₄ solution as a reaction solution. The Ca ions in Ca-type PHI were involved in the formation of HA on the surface of NH₄-type PHI. The novel nanocomposite obtained here is an ideal material for adsorbing and fixing radioactive elements.