Preparation and Characterization of Imprinted Porous Materials with High Selectivity for Luteolin

Abstract

In order to selectively separate luteolin from its crude solution, we synthesized imprinted porous materials with high recognition specificity for luteolin, using an imprinting technique. Modified luteolin was used as template, vinyltriethoxysilane as the functional monomer, and tetraethyl orthosilicate (TEOS) as the cross-linking agent. The results showed the following optimum reaction conditions: The reaction ratio between luteolin and acryloyl chloride was 1 : 2 (0.10 g/0.20 g), adding 1.0 g precursor; the feasible elution time was 12 h; when the molar quantity of modified template molecule was 0.01 mol and ethenyltriethyloxy-silane (VTEO) was 0.04 mol, the maximum yield reached 91.6 %. All samples were tested by Brunauer-Emmett-Teller method, Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy, equilibrium adsorption experiments and selective adsorption experiments. It was found that the imprinted porous materials showed excellent selectivity for luteolin in aqueous solution. Characterization by FTIR suggested that an addition reaction had occurred between the modified template molecule and VTEO while forming ester bonds in the functional precursor. Results from pore structure analysis indicated that the imprinted porous materials had good channels, and the average pore size of the prepared porous materials was between 35.85 and 95.82 Å. Adsorption dynamics analysis suggested that, when the adsorption time reached 3 h, the adsorption process had reached balance and the adsorption capacity was at steady state. These porous materials had highly selective recognition properties and high equilibrium adsorption capacity for the template molecule. The equilibrium adsorption capacity of the imprinted porous materials to the template molecule was 11.4 times that of the blank porous materials.