The effect of hydroxyapatite (HA) particles with various grain sizes and dentifrice containing hydroxyapatite on aqueous cadmium adsorption was studied. Three kinds of suspensions were prepared by adding dentifrice to HA suspensions containing 3% HA with grain sizes of 20 nm

60 nm and 12 μm with different concentrations. Cadmium ion solutions with initial concentration of 0.2 mg/L were mixed with HA suspensions and dentifrice suspensions respectively

and then were kept still for 24 h. The residual cadmium ion concentration of the supernatant was measured by inductively coupled plasma emission spectrometer

and the sorption rate of cadmium ion was calculated. The sorption rates of cadmium ion of HA particle with 3 grain sizes were above 70%

and 20 nm HA was the best.The sorption rates of cadmium ion of dentifrice containing HA were over 50% by average

and dentifrice containing 20nm HA was the highest. Pure HA and dentifrice containing HA could absorb cadmium ions. HA with size of 20 nm showed the best sorption property. The sorption property decreased by adding dentifrice.