Immobilization of TiO_2 nanopowders in multilayer fluorinated coatings for highly efficient clear and turbid wastewater remediation

摘要

The use of nanosized photocatalytic TiO_2 in suspension or slurry type reactors is well reported. However, the industrial feasibility of such systems is limited, on account of the low quantum efficiency reported for slurry processes and of the need for a post-treatment catalyst recovery stage, which may present poor efficiency, with the double drawback of dispersing nanoparticles in the environment and losing precious photocatalyst. In this work, the photodegradative activity of titanium dioxide immobilized into a multilayered transparent fluoropolymeric matrix has been studied. Several TiO_2 nanostructured powders featuring different primary particle size, crystalline phase and specific surface area have been produced by the flame spray pyrolysis (FSP) of organic solutions containing titanium (IV) isopropoxide. The activity of such powders has been tested and compared to that of TiO_2 P25 by Evonik Degussa, which is the reference nanopowder commonly employed in the evaluation of the photocatalytic activity of non-commercial TiO_2. A multilayer ionomeric-perfluorinated matrix has been used to immobilize the powders, having high chemical resistance and transparency towards UV light, good permeability to oxygen and good wettability to favor interactions with the polluted aqueous solutions.