Molecularly imprinted membranes in advanced separations

The prompt industrial development, the necessity of recovering and recycling raw materials as well as the increased demand of high purification level of targeted compounds amplified the awareness and the activities devoted to the production of highly selective and efficient separation systems. In this scenario, the development of membrane science and the advent of the imprinting technology assumed a significant role in the production of molecularly imprinted membranes (MIMs). They are “smart membranes” that exhibit selective recognition properties towards specific compounds of interest called “templates” and are able of separating them from a mixture containing other substances or similar compounds, including their structural homologues [1, 2]. In comparison with traditional membranes MIMs exhibit improved selectivity but preserve their stability and permeability. Their ability of achieving high separation level of the target compounds through their selective facilitated or retarded permeation as well as via their selective adsorption, has rendered them promising for the development of advanced sustainable membrane separation processes [2]. Nowadays, MIMs are applied for the selective detection and separation of a wide variety of compounds, including bioactive compounds, pharmaceuticals, optical isomers, pesticides and so on. This work summarized three examples dealing with the preparation and application of MIMs in nutraceutical and pharmaceutical fields. In particular, the application of the alternative molecular imprinting for producing phase-inversion MIMs able of selectively separating the flavonoid quercetin, the vitamin B9 (folic acid) and the xanthine theophillyne used in the treatment of the chronic obstructive pulmonary disease are presented. All the prepared imprinted membranes were competitive with their corresponding non-imprinted ones and exhibited good selectivity towards template molecules with respect competing similar compounds.