Highly effective buoyant photocatalyst prepared with a novel layered-TiO 2 configuration on polypropylene fabric and the degradation performance for methyl orange dye under UV–Vis and Vis lights

Abstract

Different layers of TiO 2 were immobilized on polypropylene fabric (PPF) to obtain highly active buoyant photocatalysts. The prepared photocatalysts were examined for the degradation of methyl orange (MO) dye under UV and visible lights. To increase the loading rate of TiO 2, a rutile TiO 2 layer was first immobilized onto PPF, followed by another anatase TiO 2 layer on the top (denoted as ‘ R + A’). In comparison with PPF immobilized with one layer of anatase TiO 2 (denoted as ‘ A’), or two layers of anatase TiO 2 (denoted as ‘ A + A’) or even three layers of anatase TiO 2 (denoted as ‘ A + A + A’), the ‘ R + A’ approach achieved the highest loading of 116 g TiO 2 per square meter PPF, being as much as about 1.5–2.3 times of those immobilized by other approaches. All the prepared photocatalysts were buoyant and the ‘ R + A’ photocatalyst appeared to be the most active one for both UV and visible lights. Under an artificial light source (with UV 48 W/m 2 and visible light 178 W/m 2), MO dye, though usually difficult to be degraded by other methods, was found to be completely degraded within 2 h by the ‘ R + A’ photocatalyst (at an initial MO dye concentration of 15 mg/L). High performance liquid chromatography (HPLC) analysis indicated that the MO dye degradation under UV or visible light possibly followed different degradation pathways in the catalytic reactions.