Abstract:

At present，the development of green and efficient heavy metal adsorption materials has attracted extensive attention.Using diatomite as raw material，two kinds of silicate materials，namely，magadiite and analcime，were selectively prepared by hydrothermal method.The Na⁺ between the layers of wheat hydroxysodalite could exchange cations with Li⁺，Mg²⁺，Zn²⁺，Co²⁺，Ni²⁺，Cu²⁺，etc.，and maintain the stability of the layered parent framework.The adsorption kinetics and mechanisms were detailedly studied by using Co²⁺ and Ni²⁺ adsorption.It is indicated that the distance of magadiite lamellar structure was reduced from 1.56 nm to 0.24 nm（Co²⁺）and 0.23 nm（Ni²⁺）.The maximum adsorption capacity towards Co²⁺ and Ni²⁺ reached 45 mg/g and 39 mg/g at room temperature，respectively.The adsorption processes were fitted with the Langmuir model.The released Na⁺ was approximate double of the adsorbed divalent Co²⁺ and Ni²⁺，showing that cation exchange dominated the adsorption processes.Thus，the prepared magadiite materials demonstrated great potentials for constructing multi-metal silicates and environmental purification applications.

Key words: diatomite, magadiite, cation exchange, layer structure