JOURNAL of the Tunisian Chemical Society

serving the Research, the Education and the Industry

Synthesis and characterization of molecularly imprinted silica for efficient adsorption of melamine

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We report on the elaboration of a new melamine molecularly imprinted silica (MIP). It was synthesized by surface molecular imprinting technique using silica gel as rigid support. Melamine was used as template molecule, 3‑mercaptopropyl trimethoxysilane immobilized onto the silica gel surface was used as a functional monomer and tetraethoxysilane (TEOS) as crosslinker. A non imprinted polymer was used (NIP) for comparison. The prepared materials were characterized by FT-IR, ATG and BET. The batch binding tests were carried out to evaluate the adsorption kinetics and adsorption isotherms either for MIP and NIP. Results show that the imprinted sorbent exhibits higher binding capacity toward Melamine (Qmax = 912 µg.g-1) compared to the non-imprinted one (Qmax = 338 µg.g-1). Two binding isotherm models (Langmuir and Freundlich) were used to check the adsorption mode. The Freundlich model appears as the most suitable model for both imprinted and non-imprinted materials.The adsorption kinetic data were modeled using the pseudo-first and pseudo-second order equations. The results indicated that the adsorption of MEL on MIP follows a pseudo‑second‑order kinetic. Differentiation between adsorption phenomena onto each of the two substrates has been proposed and compared to the theoretical classification of adsorption isotherms. The application of intraparticle diffusion kinetics model has indicated that intraparticle diffusion was not the only rate limiting mechanism in the adsorption process.

F. Arfaoui, N. Jaoued-Grayaa, A. Riani Khlifi, R. Kalfat

Melamine, Molecularly Imprinted Polymer, silica gel

Pages 227-236

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