Processing fly ash stabilized hydrogen titanate nano-sheets for industrial dye-removal application

• Published in: Journal of hazardous materials Vol. 229-230; pp. 177 - 182
• Main Authors: Hareesh, P., Babitha, K.B., Shukla, S.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 30.08.2012; Elsevier
• Subjects: Adsorption; Adsorption kinetics; Applied sciences; aqueous solutions; autoclaves; Chemical engineering; Coal Ash - chemistry; coatings; Coloring Agents - chemistry; Dye-adsorption; Environmental Pollutants - chemistry; Exact sciences and technology; fly ash; General treatment and storage processes; hot water treatment; hydrogen; Hydrothermal; Industrial Waste; Ion exchange; Methylene blue; Nanostructures - chemistry; nanotubes; Pollution; Reactors; silica; Sol–gel; surface area; temperature; Titanium - chemistry; titanium dioxide; Wastes; Water Purification - methods; Dye-adsorption; Adsorption kinetics; Sol–gel; Hydrothermal; Methylene blue; Discoloration; Dyes; Stabilization; Waste treatment; Specific surface area; Fly ash; Hydrothermal treatment; Manufacturing; Ion exchange; Intermediate product; Microsphere; Sol-gel; Electrostatic interaction; Dissolution; Adsorption; Autoclave; Morphology; Physicochemical purification; Kinetics; Aqueous solution; Titanium oxide; Catalyst; Hydrothermal condition
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2012.05.093

► Fly ash (FA) is obtained from National Thermal Power Corporation (NTPC), India. ► Hydrogen titanate nano-sheets (HTNS) are processed via hydrothermal. ► FA constituents stabilize the hydrogen titanate in the nano-sheet morphology. ► HTNS exhibit higher specific surface-area and pore volume. ► HTNS show dye-adsorption capacity larger than that of as-received FA. We report a new method for the processing of fly ash (FA) stabilized hydrogen titanate nano-sheets in the form of aggregated microspheres. The industrial silica-based FA has been utilized for this purpose which has been surface-modified by coating with the anatase-titania (TiO2) via sol–gel. The anatase-TiO2 coated FA particles are subjected to the hydrothermal treatment in an autoclave under high temperature and pressure conditions in a highly alkaline solution. The hydrothermal conditions cause dissolution of silica resulting in the disintegration of other constituents of FA which are adsorbed in ionic and/or oxidized form on the surface of intermediate product of the hydrothermal treatment of anatase-TiO2, specifically the hydrogen titanate. The adsorption of FA constituents has resulted in the stabilization of hydrogen titanate in the nano-sheet morphology instead of nanotubes. The FA stabilized hydrogen titanate nano-sheets exhibit higher specific surface-area than that of the hydrogen titanate nanotubes and have been successfully utilized for the removal of an organic synthetic-dye from an aqueous solution via surface-adsorption, involving the electrostatic-attraction and ion-exchange mechanisms operating, in the dark-condition.