Preparation and Characterization of Titania Nanoparticles from Titanium Tetrachloride and Titanium Sulfate Flocculation of Dye Wastewater

Pollutants in dye wastewater significantly vary due to the large number of dyes and other chemical compounds used in dyeing processes. The major compounds in dye wastewater are desizing and scouring agents, bleaches, reducing agents, detergents and wetting agents, finishing agents, organic acids and dyes, and fluorescent brighteners1). Physical, chemical and biological methods have been applied to remove high concentrations of such pollutants, but dye wastewater is generally nutrient deficient. Therefore, direct application of a biological process is not suitable for dye wastewater, so physico-chemical treatment based on flocculation is widely used for treating dye wastewater. Flocculation uses inorganic coagulants (FeSO4 and Al2(SO4)3) or organic polymers2) to remove color, organic acids, and some metals in dye wastewater3). However, this treatment produces large amounts of sludge requiring disposal. The problem of sludge can be resolved using an alternative Ti-salt coagulant4). Ti-salt flocculation allows a large amount of sludge to produce a valuable byproduct, titanium dioxide (TiO2) nanoparticles, after incineration of the sludge4). The recycled TiO2 produced from the Ti-salt flocculation sludge has high photoactivity and particle size of about 25 nm, which implies high potential for both TiO2 application and sludge reduction. The present study investigated flocculation of dye wastewater using TiCl4 and Ti(SO4)2 coagulants to compare the efficiency of dye wastewater flocculation in terms of chemical oxygen demand (COD) removal and precipitation efficiency. The experiments produced 167 Journal of the Japan Petroleum Institute, 53, (3), 167-172 (2010)