Rapid atmospheric plasma spray coating preparation and photocatalytic activity of macroporous titania nanocrystalline membranes

Abstract

Macroporous TiO 2 nanocrystalline (NC) membranes with average pore size of 0.35 μm were successfully fabricated by coating on an alumina support via a rapid atmospheric plasma spraying (APS) approach. The as-prepared TiO 2 and P25 membranes were first tested for photocatalytic activity using Reactive Black-5 (RB5) dye in a batch reactor with UV light irradiation, respectively. RB5 dyes were completely decomposed with an irradiation time of 70 min, and the rate constants for the photocatalytic reactions using TiO 2 and P25 membranes were determined to be approximately 0.076 and 0.071 min −1, respectively. The photocatalytic activity of the as-prepared TiO 2 NC membranes was slightly better than P25 membranes, indicating the APS-fabricated TiO 2 NC membranes were with a high photocatalytic activity. The TiO 2 membranes were further used for the photodegradation of dextran and humic acid (HA), and the permeate fluxes of dextran and HA increased when the membranes were exposed to UV light irradiation. The dominant filtration resistances of the dextran and HA solutions were pore and cake resistances, respectively, which were reduced by a photocatalytic TiO 2 NC membrane under UV light illumination. The removal percentages of HA at an initial concentration of 2 ppm were 58% and 90% in the dark and under UV light irradiation, respectively. The increase in the HA removal resulted from the photodegradation of HA by the photocatalytic TiO 2 NC membrane. In this work, a rapid process of APS coating was first used for the preparation of macroporous TiO 2 NC membranes with high photocatalytic activities, which can be applied for water treatment, for example, in the photodegradation of bio-organisms and protein under UV light irradiation.