Facile One-Step Synthesis of Inorganic-Framework Molecularly Imprinted TiO_2/WO_3 Nanocomposite and Its Molecular Recognitive Photocatalytic Degradation of Target Contaminant

摘要

Inorganic-framework molecularly imprinted TiO_2/WO_3 nanocomposites with molecular recognitive photocatalytic activity were first prepared successfully by a facile one-step sol-gel method using 2-nitrophenol and 4-nitrophenol as template molecules, and tetrabutyl orthotitanate as titanium source as well as the precursor of functional monomer which could complex with template molecules. The template molecules could be completely removed by means of high-temperature calcination, avoiding the traditional extraction procedures that are time-as well as solvent-consuming. Compared to nonimprinted TiO_2/WO_3, the molecularly imprinted TiO_2/WO_3 shows a much higher adsorption capacity and selectivity toward the template molecules. The enhancement in terms of adsorption capacity and selectivity can be attributed to the chemical interaction between target molecules and imprinted cavities, as well as size matching between imprinted cavities and target molecules. The photocatalytic activity of molecularly imprinted TiO_2/WO_3 toward the target molecules is more than two times that of non-imprinted TiO_2/WO_3, a result of selective adsorption of target molecules on molecularly imprinted TiO_2/WO_3. The formation pathway of intermediate products in 2-nitrophenol and 4-nitrophenol degradation process was provided. Moreover, molecularry imprinted TiO_2/WO_3 exhibits high stability. The results indicate that inorganic-framework molecularly imprinted TiO_2/WO_3 nanocomposites have a promising prospect in the treatment of wastewater for irrigation.