Porous PMMA-titania composites: A step towards more sustainable photocatalysis

Abstract

TiO2 is an effective photocatalyst for the degradation of aqueous and airborne contaminants when activated by UV light. TiO2 nanoparticles are often deposited onto the surface of a support material to avoid the need for post-use removal of the nanoscale photocatalyst. Polymers have been shown to be suitable photocatalytic support materials, but solvent based methods for TiO2 deposition using hazardous organic solvents such as dichloromethane have negative and avoidable environmental repercussions. In this work, green chemistry principles have inspired a new approach to the formation of polymer–TiO2 composite materials. An existing surfactant-mediated method for the fabrication of porous poly(methylmethacrylate) (PMMA) membranes has been used to form a support material for the photocatalyst while replacing hazardous dichloromethane with the much more benign acetone. The deposition of TiO2 within the UV-transparent porous support material facilitates the construction of flow-through photocatalytic reactors for both aqueous and gas-phase applications. These systems were characterized by the photocatalytic degradation of aqueous methyl orange and gas phase carbon monoxide, electron microscopy, N2 adsorption/desorption surface area measurements, as well as long-term UV durability. The porous PMMA-TiO2 composites possess a methyl orange decolorization rate over 6 times higher than that of the non-porous composite reference materials with comparable TiO2 content. The porous materials reported here are more active, and have superior TiO2 retention than the non-porous benchmark materials, and thus provide a greener foundation for future photocatalytic applications.