Abstract:

 Rich low-grade diatomite mineral was modified with calcium carbonate so as to improve the adsorption properties of diatomite for heavy metal ions. The results show that in a single component system, the dynamic laws for the adsorption of Cu2+,Pb2+ ,Cd2+and Zn2+ on the diatomite modified by calcium carbonate obey the pseudo-second-order model and the adsorption thermodynamics laws obey the Langmuir model. In a mixed component system, because of the effect of coexisting components, the adsorption rate of Pb2+,Cd2+ and Zn2+ was decreased respectively and the adsorption rate of Cu2+ was increased, but the adsorption dynamic laws of four kinds of metal ions still obey the pseudo-second-order model; at the same time, the adsorption capacities of four kinds of metal ions on the modified diatomite were decreased obviously and only the adsorption thermodynamics law of Pb2+ obeys the Langmuir model.

Key words: diatomite, modified, heavy metals, adsorption