Titania Nanomaterials Produced from Ti-Salt Flocculated Sludge in Water Treatment

Abstract

Titania is the most widely used metal oxide for the applications of pigments, paper, solar cells and environmental purification. In order to meet the demand of a large amount of titania, our group has developed a novel process which could significantly lower the cost of waste disposal in water treatment, protect the environment and public health and yield economically valuable titania. Titanium tetrachloride (TiCl4) or titanium sulfate (Ti(SO4)2) as an alternative coagulant in water treatment has been explored for the removal of various pollutants from contaminated water or wastewater. Flocculation efficiencies of the Ti-salts were superior to those of Al- and Fe- salts with additional benefits in that a large amount of titania can be produced by calcinating the flocculated floc. The produced titania showed high photocatalytic activity for the removal of volatile organic compounds. The large amount of titania can be applied to pigments, environment and construction materials which require a lot of titania usages. This review paper presents an historical progress from fundamental to application in terms of the detailed production process, characterization, photoactivity of titania produced from Ti-salt flocculated sludge, and its various applications.