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Reverse Microemulsion Synthesis of Hydroxyapatite Nanoparticles and Adsorption Performance Study

Hydroxyapatite (HA) nanopowder was synthesized by reverse microemulsion technique using calcium nitrate and phosphoric acid as starting materials in aqueous phase. Cyclohexane was used as organic solvents, TX-100 as surfactants and n-butyl alcohol to make the emulsion. Synthesized powder was characterized by X-ray diffraction (XRD) and scanning electron microscopy(SEM). The results showed that different pH values and temperatures had significant effect on the purity and crystallinity of HA by using the reverse microemulsion. When the pH value is 11 and at 700°C, high purity and well crystallinity HA was obtained. There is a dicalcium phosphate phase present at pH 9, which is easily disassembled to CPP at 700°C. This HA powders have a rapid Cu2+ and Cd2+ sorption rate and good removal efficiency. The removal rates for heavy metal ions were Cd2+＞Cu2+.