ABSTRACT More than 2,000,000 tons of silica nanoparticles (NPs) are produced annually in the world to cover the needs of nanotechnologies. Inevitably, a quantity of NPs, will be in industrial discharges and domestic, or even in water resources. Share their high surface reactivity, these NPs may also carry with them through a specific adsorption of other toxic chemical pollutants inherent to the industrial sectors. To preserve public health and the environment from this pollution, it is necessary to remedy the potential pollution. In this context, the main motivation of this work is to answer this environmental issue by proposing a scheme of remediation based on the use of a conventional treatment process. The process of elimination nanoparticles by coagulation/flocculation was selected for its simplicity and also for its universal use. The NPs of industrial silica S30R50 were used as support to develop the process. The optimization of coagulation/flocculation, was greatly facilitated by the use of laser diffraction online. This technique allowed to follow the dynamic character of the treatment and to determine the size and the most relevant textural parameters (density, porosity and fractal dimension) of the flocs depending on the nature of the used reagents. The critical concentrations of different coagulants and flocculants used were determined by electrophoresis and turbidity. The ratio of their charge density/molecular weight has conditioned the quality of separation, the floc size and their texture. Excellent coagulation/flocculation performances are reached using organic reagents authorized by the Directorate General for Health of several countries. After optimization of the process, the size distributions are between 10 μm and 1 mm, with fractal dimensions (compactness) ranging from 2.3 to 2.5. The performances obtained show that the use of cationic polymers is a promising potential route to treat other types of NPs. The treatment proposed to reach a ratio of average diameters dFloc/dNP of 3500, and therefore it facilitates the elimination of these NPs agglomerated by filtration.
Cite this paper
Bizi, M. (2012) Stability and flocculation of nanosilica by conventional organic polymer. Natural Science, 4, 372-385. doi: 10.4236/ns.2012.46052.
 Oberd?rster, G. (2000) Toxicology of ultrafine particles: In vivo studies. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 358, 2719-2740.
 Banfield, J.F. and Navrotsky, A. (2001) Nanoparticles and the environment. Reviews in mineralogy and geochemistry. Mineralogical Society of America, Washington DC.
 Yean, S., Cong, L., Yavuz, C.T., Mayo, J.T., Yu, W.W., Kan, A.T., Colvin, V.L., and Tomson, M.B. (2005) Effect of magnetic particle size on adsorption and desorption of arsenite and arsenate. Journal of Material Research, 20, 3255-3264. doi:10.1557/jmr.2005.0403
 Clariant Klebosol Brochure 2010.
 Zantye, P.B., Kumar, A. and Sikder, A.K. (2004) Chemical mechanical planarization for microelectronics applications. Materials Science and Engineering, 45, 89-220.
 Brunauer, S., Emmett, P.H. and Teller, E. (1938) Adsorption of gases in multimolecular layers. Journal of the American Chemical Society, 60, 309-319.
 Marler, B. (1988) On the relationship between refractive index and density for SiO2 polymorphs. Physics and Chemistry of Minerals, 16, 286-290.
 Murillo, A.G. (2002) Elaboration, propriétés structurales, optiques et spectroscopiques de films sol-gel scintillants de Gd2O3 et Lu2O3 dopés Eu3+. PhD Thesis, Claude Bernard Lyon I University, Lyon.
 Henry, D.C. (1931) The cataphoresis of suspended particles. Part I. The equation of cataphoresis. Proceedings of the Royal Society, London Series, 133, 106-129.
 Ohshima, H. (1994) A simple expression for henry’s function for the retardation effect in electrophoresis of spherical colloidal particles. Journal of Colloid and Interface Science, 168, 269-271.
 Carman, P.C. (1940) Constitution of colloidal silica. Transactions of the Faraday Society, 36, 964-973.
 Iler, R.K. (1955) Colloid chemistry of silica and silicates. Cornell University Press, Ithaca, New York.
 Kent, D.B., Tripathi, V.S., Ball, N.B., Leckie, J.O. and Siegel, M.D. (1988) Surface-complexation modeling of radionuclide adsorption in subsurface environments. NUREG/CR-4807, US Nuclear Regulatory Commission, Washington DC.
 Bizi, M. and Baudet, G. (2006) Contribution of static light scattering to the textural characterization of large aggregates. Journal of Colloid Interface Science, 300, 200-209.
 Van de Hulst, H.C. (1981) Light scattering by small particles. Dover Publications, Inc., New York.
 Kerker, M. (1969) The scattering of light and other electromagnetic radiation. Academic Press, New York.
 Guinier, A. and Fournet, G. (1955) Small angle scattering of X-rays. John Wiley and Son, New York.
 Bohren, C.F. and Huffman, D.R. (1983) Absorption and scattering of light by small particles. John Wiley and Sons, New York.
 Michard, G. (1989) Chemical balances in natural waters. Eds Published, Paris.
 Bizi, M. (2012) French National Research Agency Report, NANOSEP-ANR-08-ECOT-009, RP-61015-FR.
 Bolt, G.H. (1957) Determination of the charge density of silica sols. Journal of Physical Chemistry, 61, 1166-1169.
 Iler, R.K. (1979) The chemistry of silica: Solubility, polymerization, colloid and surface properties and biochemistry of silica. John Wiley and Sons, New York.
 Prezzi, M., Monteiro, P.J.M. and Sposito, G. (1998) Alkali-silica reaction. Part 2: The effect of chemical additives. ACI Materials Journal, 95, 3-10.
 Cases, J.M. (1969) Point de charge nulle et structures des silicates. Journal of Chemical Physics, 66, 1602-1611.
 Gregory, J. (1973) Rates of flocculation of latex particles by cationic polymers. Journal of Colloid Interface Science, 42, 448-456. doi:10.1016/0021-9797(73)90311-1
 Gregory, J. (1987) Flocculation by polymers and poly- electrolytes. In: Tadros, T.F., Ed., Solid-Liquid Dispersions, Academic Press, London.
 Bizi, M. and Gaboriau, H. (2008) Flocculation analysis and control system by laser diffractometry at industrial scale. AIChE Journal, 54, 132-137.
 Thouy, R. and Jullien, R. (1996) Structure factors for fractal aggregates built off-lattice with tunable fractal dimension. Journal of Physics, 6, 1365-1376.
 Matsumoto, K. and Suganuma, A. (1977) Settling velocity of a permeable model floc. Chemical Engineering Science, 32, 445-447.