Adsorption experiments were conducted with reciprocate
shaker (incubator personal Lt, TAI TEC, Japan). Various amounts
of CaCO3 (particle size of 0.1 mm) were added into HA solutions
and shaken for 2 h. The solution pH was adjusted to 7.0 with
0.1 mol/L HCl. After the experiments, supernatant samples were
withdrawn and
filtered through 0.45 mm pore diameter membrane
filter (mixed cellulose ester, ADVANTEC, Japan) and the UV
absorbance at 260 nm was measured. The solution pH was