Photocatalytic TiO2 films and membranes for the development of efficient wastewater treatment and reuse systems

In order to develop efficient photocatalytic TiO2 films and membranes for application in water and wastewater treatment and reuse systems, there is a great need to tailor-design the structural properties of TiO2 material and enhance its photocatalytic activity. Through a simple sol–gel route, employing self-assembled surfactant molecules as pore directing agents along with acetic acid-based sol–gel route, we have fabricated nanostructured crystalline TiO2 thin films and TiO2/Al2O3 composite membranes with simultaneous photocatalytic, disinfection, separation, and anti-biofouling properties. The highly porous TiO2 material exhibited high specific surface area and porosity, narrow pore size distribution, homogeneity without cracks and pinholes, active anatase crystal phase, and small crystallite size. These TiO2 materials were highly efficient in the decomposition of methylene blue dye and creatinine, destruction of biological toxins (microcystin-LR), and inactivation of pathogenic microorganisms (Escherichia coli). Moreover, the photocatalytic TiO2 membranes exhibited not only high water permeability and sharp polyethylene glycol retention but also less adsorption fouling tendency. Here, we report results on the synthesis, characterization, and environmental application and implication of photocatalytic TiO2 films and membranes.

The sol–gel method modified with surfactant presented in this study was successfully used to prepare nanostructured photocatalytic TiO2 materials with high photocatalytic activity and desired pore structure. The synthesis route resulted in promising TiO2 films and membranes with better structural properties such as homogeneity, controlled pore size distribution, and high pore volume, as well as enhanced catalytic properties such as high surface area, active anatase phase, and small crystal size. Due to their highly porous structure, the photocatalytic TiO2 films and membranes tested here were very effective in destroying organic pollutants in water such as biological toxins, methylene blue dye, and creatinine, as well as in inactivating pathogenic microorganisms such as E. coli. In addition, the photocatalytic TiO2/Al2O3 composite membranes exhibited high water permeability, reliable organic retention, and anti-biofouling properties. Consequently, these photocatalytic TiO2 films and membranes, when further optimized, can be applied in the development of promising water and wastewater treatment and reuse systems.