Separation of phenylalanine by ultrafiltration using D-Phe imprinted polyacrylonitrile-poly(acrylic acid)-poly(acryl amide) terpolymer membrane

A D-phenylalanine (D-Phe) imprinted terpolymer P(AN-AA-AAm) membrane was prepared by the wet phase inversion method. Acrylamide (AAm) and acrylic acid (AA) were used as the functional monomer and acrylonitrile (AN) was used as a physical cross linker. The template molecules were removed from the terpolymer matrix by washing with a 5 percent acetic acid solution. The removal of template molecules from the membrane matrix increased the population of free COOH groups and reduced that of dimerized COOH groups in the membrane matrix, which is an indirect evidence of the formation of recognition sites. The adsorption selectivity of the D-Phe imprinted terpolymer membrane prepared by in-situ implanting method was 0.37 at pH 2 after 3 h batch adsorption using 100 mg Phe/l racemate solution and reached nearly 1 after 24 h. In the ultrafiltration process, the permselectivity was 0.38 at pH 2 after 2.5 min. Separation of D-Phe from the racemate solution was demonstrated by a repeated ultrafiltration batch work.