Development of molecularly imprinted membranes able to selectively recognize toxic organic compounds

Aim of this work was the development of molecularly imprinted membranes (MIMs) for the selective recognition of dimethoate, which is a pesticide used in agricultural productivity. It was identified as one type of organophosphorus pesticides listed in guidelines for drinking water by World Health Organization [1]. Is emerging as contaminant in water. In fact, it is highly soluble in water and adsorbs very weakly to soil particles. MIMs are advanced functional membranes with high specificity and selectivity toward a molecule of specific interest named template. This peculiarity is due to the presence of specific recognition sites in the membrane matrix, which are complementary to the template in chemical function, shape and size. These sites contains the molecular memory of the template. The molecular imprinting technique [2] to introduce them into a membrane is used. The phase inversion technique for preparing MIMs from polymers ad hoc synthesized was used. Polyacrylonitrile and its co-polymers, with different functional co-monomers (acrylic acid, methacrylic acid, itaconic acid and acrylamide) were chosed as membrane forming material. Membranes were characterized by IR analysis, pure water water permeability and contact angle measurements. SEM analysis were also done. The membrane performance was evaluated by means of rebinding experiments aiming to determine the membranes affinity to the template molecules versus other structural analogues pesticides. First, screening experiments were carried out in order to determine the best functional monomer able to interact with the template [3]. Subsequently, some advances of imprinting technique [4] for developing novel hybrid imprinted membranes with enhanced recognition properties towards dimethoate were employed. In this perspective, cross-linked imprinted polymer powders were hybridized with Poly(acrylonitrile-co-acrylic acid) co-polymer. Results showed that the best functional monomer for interacting with the template was acrylic acid. Hybrid membranes exhibited high hydraulic permeability and selective recognition ability with respect to other kind of membranes. Results of this wok suggest that dimethoate-imprinted membranes could be potentially employed for the detection and/or removal of this pesticide from polluted sites.