Recovery of high specific area silica and sodium fluoride from sodium hexafluorosilicate

Abstract

Sodium fluoride and high specific area silica were synthesized by using sodium hexafluorosilicate (Na₂SiF₆) and sodium carbonate decahydrate (Na₂CO₃·10H₂O). The influencing factors of react temperature, contact time, sodium dodecyl sulfate (SDS) and molar ratio of Na₂SiF₆ to Na₂CO₃·10H₂O were investigated. The optimum process involves the reaction of 0.075 mol Na₂SiF₆ and 150 mL, 0.225 mol Na₂CO₃·10H₂O (molar ratio of 1:3) at 85 °C for 90 min, and 2.0×10⁻³ mol sodium dodecyl sulfate (SDS) as additive. The results show that the purities of SiO₂ and NaF at extraction yields of 96.5% and 98.0% are 91.0% and 98.6%, respectively. The obtained SiO₂ were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared ray (FTIR), differential scanning calorimetry and thermogravimetric analysis (DSC-TGA), N₂ absorption/desorption (BET) and laser particle size analyzer. The result demonstrates that SiO₂ particles have a high BET surface area of 103 m²/g, and a mean grain size of 985 nm.

Keywords

recovery / sodium hexafluosilicate / sodium fluoride / silica

References

[1] LiJ, ZuoG-l, LiR-lin. Preparation of sodium fluoride and white carbon black from sodium flurosilicate and natural brine [J]. Inorganic Chemical Industry, 2010, 42(7): 52-54

[2] ChenZ-m, ChenX-rong. Sodium fluoride production out of fluorosilicic acid solution by direct one-step process [J]. Nonferrous Metals Science and Engineering, 2011, 3(2): 32-35

[3] ZhongZ-x, LiuX, ChenR-z, XingW-h, XuN-ping. Adding microsized silica particles to the catalysis/ultrafiltration system catalyst: Catalyst dissolution inhibition and flux enhancement [J]. Industrial & Engineering Chemistry Research, 2009, 48(10): 4933-4938

[4] BanerjeeA K, LayaM S, VereavegasW J. Silica gel in organic synthesis [J]. Russian Chemical Reviews, 2001, 70(11): 971-990

[5] MeynenV, CoolP, VansantE F. Verified syntheses of mesoporous materials [J]. Microporous Mesoporous Material, 2009, 125(3): 170-223

[6] HyoS Y, KangR, ChurlK L, DongH Y. Two-step ammoniation of by-product fluosilicic acid to produce high quality amorphous silica [J]. Korean Journal of Chemical Engineering, 2000, 17(4): 401-408

[7] AndrezejK, BozenaR, MarekM. Silica recovery from waste obtained in hydrofluoric acid and aluminum fluoride production from fluosilicic acid [J]. Journal of Hazardous Materials, 1996, 48(1/2/3): 31-49

[8] SarawadeP B, KimJ K, HilongaA, KimH T. Recovery of high surface area mesoporous silica from waste hexafluorosilicic acid (H₂SiF₆) of fertilizer industry [J]. Journal of Hazardous Materials, 2010, 173(1/2/3): 576-580

[9] ShiG-ming. A new process of sodium fluoride production by sodium carbonate decahydrate [J]. Chlor-Alkali Industry, 2009, 45(11): 29-30

[10] AlexanderF I, AllanS M. Monentum and mass transfer in supersaturated solutions and crystal growth from solution [J]. Journal of Crystal Growth, 1997, 174(1/2/3/4): 362-368

[11] KalapathyU, ProctorA, SchultzJ. Silica xerogels from rice hull ash: Structure, density and mechanical strength as affected by gelation pH and silica concentration [J]. Journal of Chemical Technology and Biotechnology, 2000, 75(6): 464-468

[12] SorapongJ. Polyethyleneimine/sodium dodecyl sulphate adsorbed silica particles and their adsorption properties [J]. Colloids and Surfaces A, 2010, 369(1/2/3): 186-190

[13] WangW, GuB-h, LiangL-yuan. Effect of anionic surfactants on synthesis and self-assembly of silica colloidal nanoparticles [J]. Journal of Colloid and Interface Science, 2007, 313(1): 169-173

[14] SavitaR K, AndrewP. Silica gel from rice hull ash: preparation and characterization [J]. Cereal Chemistry, 1998, 75(4): 484-487

[15] ChukinG D, IgnatevaL A. A study of the active centers of silica gel by IR spectroscopy [J]. Journal of Applied Spectroscopy, 1968, 5(8): 527-529

[16] LiuY-r, TuM-j, ZhangJ, SongZ-r, TangYing. Synthesis of hydrophobic mesoporous silica films using poly (dimethylsiloxane)-poly (ethylene oxide) (PDMS-PEO) as co-template [J]. Microporous and Mesoporous Materials, 2011, 145(1/2/3): 182-187

[17] HuaZ-l, ShiJ-l, WangL, ZhangW-hua. Preparation of mesoporous silica films on a glass slide: Surfactant template removal by solvent extraction [J]. Journal of Non-crystalline Solids, 2001, 292(1/2/3): 177-183

[18] WangL-j, LuA-h, WangC-q, ZhengX-s, ZhaoD-j, LiuRui. Nano-fibriform production of silica from natural chrysotile [J]. Journal of Colloid and Interface Science, 2006, 295(2): 436-439

[19] ZhuravlevL T. The surface chemistry of amorphous silica: Zhuravlev model [J]. Colloids and Surfaces A, 2000, 173(1/2/3): 1-38

[20] GorlovY L, GolovatyiV G, KonoplyaM M, ChuikoA A. Field desorption of water from the surface of silica and the structure of its hydrate coating [J]. Theoretical and Experimental Chemistry, 1980, 16(2): 164-168

[21] FripiatJ J, UytterhoevenJ. Hydroxyl content in silica gel “aerosil” [J]. The Journal of Physical and Chemistry, 1962, 66(5): 800-805

[22] KiseleviA V, UvarovA V. Infrared spectra and electron spin resonance of aluminium, silica and titanium oxides and of adsorbed substances [J]. Surface and Science, 1967, 4(4): 399-421

[23] HassanH H, AteiaE, DarwishN A, HalimS F, Abd ElazizA K. Effect of filler concentration on the physic-mechanical properties of super abrasion furnace black and silica loaded styrene butadiene rubber [J]. Materials and Design, 2012, 34: 533-540

[24] SarawutP, NittayaR. Mechanical and damping properties of silica/nature rubber composites prepared from latex system [J]. Polymer Testing, 2011, 30(5): 515-526

[25] RenX-d, LiuY-e, PangG-l, ZhenW-j, ChenJ-j, ChangC-feng. Study on preparation process of silica with wollastonite from Hami [J]. Non-Metallic Mines, 2010, 33(2): 11-14