Abstract: We studied the absorption of cadmium by medical stone in vitro under the following four different conditions,which were the amount of medical stone added,solution pH,solution initial concentration and reaction time aiming at finding out the optimum absorption conditions. Besides we studied the absorption of other mineral elements too. The results showed that the absorption rate would increase when the amount of medical stone added and the solution pH increased,while it would fall when the solution initial concentration increased,the unit absorption quantity would peak as the concentration being 50 mg/L, and with the initial concentration of cadmium increasing, the absorption rate reduced.The time of absorption equilibrium was 60 min. The mixed solution contained zinc,iron,cooper,selenium,manganese,cadmium and cobalt,in which we could see that the adsorption capacity of 7 metals followed Cd＞Fe＞Se＞Co＞Cu＞Zn＞Mn.

Key words: medical stone; heavy metal; cadmium; absorption