title: Recovery of high surface area mesoporous silica from waste hexafluorosilicic acid (H2SiF6) of fertilizer industry.
abstract: In this article we report recovery of mesoporous silica from the waste material (hexafluorosilicic acid) of phosphate fertilizer industry. The process involves the reaction of hexafluorosilicic acid (50 ml, 24 wt% H(2)SiF(6)) and 100ml, 0.297 M Na(2)CO(3) to generate the alkaline aqueous slurry. Silica was separated from the slurry by filtration and the sodium fluoride was extracted from the aqueous solution by evaporation method. The obtained mesoporous silica was characterized by N(2) absorption/desorption (BET), thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscope (SEM), and EDS. The results confirm that the separation of silica and NaF was successful and the final products have high purity. The silica product was found to have an average pore diameter of 4.14 nm and a high surface area (up to 800 m(2)/g). The process reported in this study may significantly reduce the release of hazardous materials into the environment and it might confer economic benefits to the responsible industries.
authors.affiliation: Department of Chemical Engineering, Hanyang University, 1271 Sa 3-dong, Sangnok-gu, Ansan-si, Gyeonggi-do 426-791, Republic of Korea.
authors.forename: Pradip B
authors.initials: PB
authors.lastname: Sarawade
authors.forename: Jong-Kil
authors.initials: JK
authors.lastname: Kim
authors.forename: Askwar
authors.initials: A
authors.lastname: Hilonga
authors.forename: Hee Taik
authors.initials: HT
authors.lastname: Kim
mesh_terms: D004563:Electrochemistry; D005308:Fertilizers / Q000032:analysis*; D005459:Fluorides / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D007220:Industrial Waste / Q000032:analysis*; D007221:Industry; D008855:Microscopy, Electron, Scanning; D009584:Nitrogen / Q000737:chemistry; D016062:Porosity; D012824:Silicic Acid / Q000032:analysis*; D012822:Silicon Dioxide / Q000032:analysis*; D012969:Sodium Fluoride / Q000737:chemistry; D013499:Surface Properties; D013818:Thermogravimetry; D014961:X-Ray Diffraction
chemical_list: D005308:Fertilizers; D007202:Indicators and Reagents; D007220:Industrial Waste; D012824:Silicic Acid; C035291:hexafluorosilicic acid; D012822:Silicon Dioxide; D012969:Sodium Fluoride; D009584:Nitrogen; D005459:Fluorides