Preferential removal of pesticides from water by molecular imprinting on TiO2 photocatalysts

Abstract

In order to achieve a selective removal of specific pesticides from water, we synthesized, through the sol-gel technique, molecularly imprinted TiO2 photocatalysts with the only use of the standard reactants of the TiO2 sol-gel synthesis together with the pesticide molecules, without any addition of further reactants supports or matrices. It is a new, easy, smart and scalable method that avoid the multistep and solvent-consuming procedures, typical of the molecular imprinting. Two widely-used pesticides, i.e. the herbicide 2,4D, and the insecticide imidacloprid, were chosen as template for the molecular imprinting and as contaminants target for the photocatalytic tests. A remarkable enhancement of the photocatalytic activity was verified with the TiO2 imprinted with the corresponding pesticide-target. The selectivity of the photodegradation process was verified thanks to the comparison with the degradation of pesticides not-used as template. Furthermore, the eventual toxic effects of the molecularly imprinted materials were evaluated by biological tests.The combination of molecular imprinting with photocatalysis, here investigated for the first time with pesticides, it is a promising strategy to selectively catch (through the molecular imprinting process) and degrade (through the photocatalysis) specific organic contaminants from water.