Abstract
Titanium dioxide (TiO2) is the most widely used metal oxide for environmental applications, cosmetics, paints, electronic paper and solar cells, so demand is increasing rapidly. TiO2 can be produced from Ti-flocculated sludge, which is superior to the commercially available TiO2 in terms of photocatalytic activity and surface area. This process also reduces the amount of sludge for disposal after waste water treatment. In this study, flocculation of dye wastewater using TiCl4 and Ti(SO4)2 coagulants was investigated to prepare TiO2 nanoparticles from Ti-salt flocculated sludge. Both coagulants showed high flocculation performance in removing organic matter (77%), total nitrogen (76%) and total phosphorus (95%) from dye wastewater. Therefore, Ti-salt coagulants can be used in dye wastewater treatment. Incineration of the Ti-salt flocculated sludge at 600°C was performed to produce TiO2 nanoparticles. Detailed characteristics of the TiO2 nanoparticles were investigated in terms of X-ray diffraction, surface area, functional group, microscopy and photocatalytic activity. The TiO2 produced from TiCl4 and Ti(SO4)2 flocculated sludge (DCT and DST, respectively) had only the anatase structure with 20 nm particle size. The specific area of DCT and DST was 71 and 69 m2/g, respectively. Both DCT and DST were doped with carbon, silicon and sodium. Both exhibited high photocatalytic activity with complete degradation of acetaldehyde within 80 min under UV irradiation. These findings imply that TiO2 nanoparticles produced from wastewater sludge have significant potential for applications such as photocatalyst bricks, ceramic filters for air/water purification, and selective catalytic reduction catalysts.
