Evaluation of molecularly imprinted polymer blend filtration membranes under solid phase extraction conditions.
Molecularly imprinted polymer (MIP) blend membranes from cellulose acetate (CA) and sulfonated polysulfone (SPS) with 100/0, 95/5, 90/10 and 85/15 compns. and using Rhodamine B (Rh B) as template mol. were prepd. by the phase inversion technique. Blank membranes for structural and functional evaluation were prepd. under the same conditions without addn. of Rh B. Step by step template removal was performed using water and methanol as extg. solvents under controlled conditions. Pure water permeability studies were performed at 3 bar, and contact angle measurements revealed that the MIP blends with a higher SPS content were somewhat more hydrophobic than CA. Then, all membranes were characterized as membrane adsorbers: Rh B uptake from dil. aq. solns. was measured in filtration expts. (membrane solid phase extn.). The MIP CA/SPS blend membrane with 95/5 compn. had the highest binding capacity. Rh B binding to all MIP membranes was significantly higher than binding to the resp. blank samples. Washing with water and sodium chloride and subsequent elution with methanol were carried out in order to identify and differentiate the weak and strong binding to the membrane surface. The obtained data reveal that mol. imprinting via phase inversion yields not only a higher no. of Rh B binding sites than prepn. without template but also a larger fraction of sites binding strongly under aq. conditions. Considering the impact of SPS content onto MIP surface hydrophobicity, an unexpected contribution of the polysulfone backbone to mol. recognition was postulated. Full recovery of the bound template and reusability of the membrane adsorbers were also demonstrated.
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