Analytical Sciences

Extraction of Metal Ions Using Chemically Modified Silica Gel Covalently Bonded with 4,4′-Diaminodiphenylether and 4,4′-Diaminodiphenylsulfone-salicylaldehyde Schiff Bases

R. K. DEY,* Usha JHA,* A. C. SINGH,* S. SAMAL,** and Alok R. RAY***

*Department of Applied Chemistry, Birla Institute of Technology, Mesra-835 215, Ranchi, India
**Department of Material Science and Engineering, K-JIST, 1, Oryong Dong, Buk-gu, South Korea
***Centre for Biomedical Engineering, Indian Institute of Technology, New Delhi-110 016, India

Two new chelating materials (Si-DDE-o-HB, and Si-DDS-o-HB) were synthesized by modifying the activated silica gel phase with Schiff bases of 4,4′-diaminodiphenylether (DDE)/4,4′-diaminodiphenylsulfone (DDS) and o-hydroxybenzaldehyde (o-HB). The synthesized materials were characterized by FTIR and BET surface area measurement techniques. The extraction of metal ions such as Zn²⁺, Mn²⁺ and Cr³⁺ by the chelating material Si-DDE-o-HB was found to be higher than that by Si-DDS-o-HB. The order of metal sorption was found to be Zn²⁺ > Mn²⁺ > Cr³⁺. The correlation coefficients for Freundlich and Langmuir adsorption isotherms were compared for the sorption of Zn²⁺ onto the chelating material. The loading and elution of the metal ion solution was examined at optimum pH 7.5 and 0.5 cm³ min^-1 flow rate of the solution using a column technique. The preconcentration factor for the elution of Zn²⁺ using dilute HNO₃ was found to be 66.2 with a breakthrough volume of 15 cm³. The data obtained for the preconcentration of Zn²⁺ by the column technique suggested that the material Si-DDE-o-HB can find industrial applications.

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