Study on preparation of composite membrane with molecular recognizing property and its selective permeance mechanism

To enhance the selectivity of separation membrane in complex system, a composite membrane with molecule recognizing property is prepared according to the molecular imprinted technology. Firstly, functional silica sol was prepared by taking the luteolin as the template molecule, the γ-aminopropyltriethoxysilane (γ-APTS) as the functional monomer and the tetraethoxysilane (TEOS) as the cross-linker, and then the composite membrane was prepared through coating and grafting on the upper-side of the Al2O3 microporous membrane by using functional silica sol and removing of the template molecule. The composite membranes were examined by scanning electron microscope (SEM), fourier transform infrared spectroscopy (FTIR), and otherwise. Meanwhile, the results showed that the functional silica gel film connected with the Al2O3 microporous membrane through chemical bond, and it had high selectivity for template molecule. The amounts of equilibrium binding are 1.87 mmol/g and 0.21 mmol/g for luteolin and rutin, respectively by binding analysis. Relative to corresponding blank membrane, the composite membrane had a more excellent recognition to luteolin in aqueous solution. The permeation and selectivity analysis showed that the selective separation of template was accomplished by using composite membrane from mixture aqueous solution containing rutin and luteolin. Evidence of the separation of the mixture indicated that the separation factor of luteolin and rutin was estimated as 14.12. The selective permeance mechanism was studied.