Fabrication of ordered microporous styrene-acrylonitrile copolymer blend imprinted membranes for selective adsorption of phenol from salicylic acid using breath figure method

Highly selective, ordered microporous molecularly imprinted membranes (MIMs) for phenol were synthesized by breath figure (BF) method using styrene-acrylonitrile copolymer (SAN) as the membrane matrix and molecularly imprinted polymer nanoparticles (nano-MIPs) as the imprinted nanoparticles. The nano-MIPs were synthesized by oil-in-water emulsion polymerization using 4-vinyl pyridine (4-VP), methyl methacrylate (MMA) or cinnamic acid (CA) as the functional monomer, respectively. The prepared nano-MIPs were characterized by transmission electron microscope (TEM) and Raman, whereas MIMs were characterized by SEM, membrane flux, and selective adsorption experiments. Morphological analysis exhibited that the addition of nano-MIPs improved the formation of ordered and well-defined porous membrane morphology. Compared with MMA-MIM and CA-MIM, the 4-VP-MIM exhibited higher membrane flux, adsorption capacity, and stronger selective binding for phenol as well as excellent permeation selectivity for phenol. Moreover, the selective effect of 4-VP-MIM on phenol was strongly affected by the amount of 4-VP imprinted nanoparticles (nano-4-VP-MIPs). The experimental data revealed that the 4-VP-MIM containing 2.0 wt % of nano-4-VP-MIPs exhibited the highest separation selectivity for the template phenol, whose selectivity coefficients for phenol relative to salicylic acid (SA) and p-hydroxybenzoic acid (p-HB) were 5.6770 and 5.5433, respectively, which was close to the predicted selectivity coefficient value.