Molecularly Imprinted Membranes with Affinity Properties for Folic Acid

The extraction of folic acid from aqueous solutions was proposed through a novel procedure based on the membrane separation process using the approach of molecular imprinting. Molecularly imprinted membranes were prepared via the phase inversion technique using poly(acrylonitrile-co-acrylamide) copolymer as the membrane material and folic acid as the template molecule. Poly(acrylonitrile)-based membranes were also prepared as the reference material. Polymer composition, membrane preparation method, and the pH used in the binding experiments were the parameters which mostly influenced the recognition properties of the imprinted membranes. In particular, the solvent evaporation method allowed to obtain poly(acrylonitrile-co-acrylamide) imprinted membranes which at pH 5.0 showed a specific binding capacity of 5.3 µmol/g_memb. Corresponding blank membranes (prepared in absence of the template molecule), only showed a poor non-specific binding of 1.0 µmol/g_memb. Polyacrylonitrile-based membranes showed lower folic acid retention (1.5 µmol/g_memb. when prepared in the presence of the template and 0.9 µmol/g_memb. when prepared in the absence of the template).