Analytical Sciences

Adsorption Behavior of Divalent Metal Ions onto Surface-functionalized Mesoporous Silicate MCM-41 Having Schiff Base Structure

Syunichi OSHIMA,*1 Hidekazu OHINATA,*2 Takushi MATSUNO,*1 Kenta TAKASAWA,*1 Yujiro WATANABE,*3 Kaoru FUJINAGA,*1 Geoffrey W. STEVENS,*4 and Yu KOMATSU*1

*1 College of Bioscience and Chemistry, Kanazawa Institute of Technology, Ishikawa 921-8501, Japan
*2 Technology Planning Div., Nomura Micro Science Co., Ltd., Kanagawa 243-0021, Japan
*3 Faculty of Bioscience and Applied Chemistry, Hosei University, Tokyo 184-8584, Japan
*4 Department of Chemical Engineering, The University of Melbourne, Victoria 3010, Australia

Surface functionalized mesoporous silicates, MCM-41s, having 3-(2-pyridylmethylideneimino)propyl group (PI-MCM-41) or 3-(2-quinolylmethylideneimino)propyl group (QI-MCM-41) were prepared via Schiff base reaction, and the adsorption behavior of metal ions onto the modified MCM-41s was investigated. The function groups on the modified MCM-41 surface were confirmed by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and elemental analysis. The metal ions examined, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, and Pb²⁺, were quantitatively adsorbed on the PI-MCM-41 and QI-MCM-41, except for Mn²⁺. In the complexation with these metal ions, it was suggested that imine-N and heterocyclic-N atoms act as donor atoms. In addition, it was considered that the hydrophobicity derived from the organo-functional groups modified on MCM-41 contributed to improving the adsorption ability.

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