Modeling the kinetics of silica nanocolloid formation and precipitation in geologically relevant aqueous solutions

Conrad, Christine F.; Icopini, Gary A.; Yasuhara, Hajime; Bandstra, Joel Z.; Brantley, Susan L.; Heaney, Peter J.

doi:10.1016/j.gca.2006.10.001

Cited by 79 publications

(55 citation statements)

References 34 publications

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“…Experiments performed on much smaller time scales, rather find average radii of the order of a few nm 7,8 , in agreement with earlier speculations 2 . Only recently has Small Angle X-Ray Scattering (SAXS) been used to in-situ determine the time evolution of the mean particle sizes in precipitation experiments induced by neutralization of a high-pH silica solution or fast cooling, allowing a more complete description of the amorphous silica precipitation characteristics 9,10 .…”

Section: Introductionsupporting

confidence: 90%

“…For these reasons, the mechanism of amorphous silica precipitation has been the subject of intensive research. Results obtained in laboratory have yielded precious information on the role of temperature, pH, ionic strength and initial supersaturation [2][3][4][5][6][7][8][9][10] . The whole precipitation process is usually described as a succession of steps.…”

Section: Introductionmentioning

confidence: 99%

“…The first stage of monomer association is promoted by increasing the total aqueous (SiO 2 ) aq concentration and by decreasing temperature. For the formation of solid particles, in some * e.mail: claudine.noguera@insp.jussieu.fr tel: 33 1 44 27 46 65 cases, the existence of an induction period is invoked, function of temperature and initial supersaturation 2,4,7,8 . It is followed by a stage, during which the degree of silica supersaturation strongly decreases, which allows the determination of global-reaction rates.…”

Section: Introductionmentioning

confidence: 99%

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Precipitation mechanism of amorphous silica nanoparticles: A simulation approach

Noguera

Fritz

Clément

2015

Journal of Colloid and Interface Science

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Hypothesis: Despite its importance in numerous industrial and natural processes, many unsolved questions remain regarding the mechanism of silica precipitation in aqueous solutions: order of the reaction, role of silica oligomers, existence of an induction time and characteristics of the particle population. This may be traced back, in past models, to the lack of account of the first stages of nucleation, size dependence of the growth law, and full particle population.Computational method: A microscopic description of the nucleation and growth of amorphous silica nanoparticles is achieved which reproduces a large set of experimental measurements, under various thermodynamic conditions. The time evolution of the solution supersaturation and of the precipitate characteristics is established.Findings : A growth law of order 6 allows reproducing experimental results, without being correlated to the presence of silica oligomers in the aqueous solution. The saturation plateaus are shown not to be due to an induction period. The characteristics of the particle population are more complex than assumed by simple precipitation models (Johnson-Mehl-Avrami-Kolmogorov or Chronomal models) and strongly depend on how supersaturation is reached. Such a microscopic approach thus proves to be well suited to elucidate the mechanism of nanoparticle formation in natural and industrial contexts.

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Section: Introductionsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Precipitation mechanism of amorphous silica nanoparticles: A simulation approach

Noguera

Fritz

Clément

2015

Journal of Colloid and Interface Science

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“…The dissolution of opal-A and reprecipitation to opal-CT, which in turn is transformed into secondary micro-crystalline quartz, may be mediated by condensation reactions of silica polymers onto metal hydroxides (Drees et al, 1989;Monger and Kelly, 2002). Moreover, nano-colloidal silica particles (<3 nm, equivalent to 300 silica monomer units) can be important for the precipitation of SiO 2 (Conrad et al, 2007). The partial dissolution of the biogenic opal-A in topsoil also provides DSi for sequestration in secondary minerals (clay neoformation and Si adsorption) in upper soil horizons (Lucas et al, 1993;Lucas, 2001;Michalopoulos and Aller, 2004;Barré et al, 2009;Opfergelt et al, 2010).…”

Section: Neoformation and Precipitation Of Si-mineralsmentioning

confidence: 99%

Tracing the origin of dissolved silicon transferred from various soil-plant systems towards rivers: a review

et al. 2011

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“…Also, colloidal silica was less stable in high ionic strength solution (0.24M) in compared to the low ionic strength solution (0.01M). Conrad et al (2007) studied the factors affecting not only the colloidal silica formation but also the conversation of colloidal silica into precipitated silica. It was found that degree of supersaturation, pH, and ionic strength are the key factors which control the growth and aggregation kinetics of colloidal silica.…”

Section: Silica Solubilitymentioning

confidence: 99%

Silica Characterization in Coal Seam Gas Water and Its Removal by Activated Alumina

Zaman¹

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The scope of work for this thesis includes: (1) characterization of silica and other scaling compounds in coal seam gas (CSG) water, and (2) study of the removal of silica from aqueous solution using activated alumina.In the first phase of this research, coal seam gas water from a full scale water treatment facility was characterized with spectroscopic and other analytical techniques. Silica and other scaling compounds, all of which were present in dissolved and non-dissolved forms, were characterized. Transmission electron microscopic analysis showed the existence of spherical siliceous particles with a size range of 10-100 nm and aggregates of 1 to 10 microns in CSG brine.Elemental characterization confirmed that the particulate matters in CSG brine consist of the following elements in decreasing order: K, Si, Sr, Ca, B, Ba, Mg, P, and S. A plant-wide silica characterization showed that the ratio of particulate to dissolved silica varies as CSG water passes through the various process units and nearly one-third of the total silicon in the RO brine was present in particulate form. In search for the origin of particulate matters, it was found that RO brine is super-saturated with respect to several carbonate and sulphate based mineral salts and precipitation of such salts during the RO process should take place and could be responsible for subsequently capturing silica in the solid phase. However, the precipitation of crystalline carbonates and sulphates is complex. X-ray diffraction analysis did not confirm the presence of common calcium carbonates or sulphates but instead showed the presence of a suite of complex minerals, to which amorphous silica and/or silica rich compounds could have adhered. A filtration study showed that majority of the siliceous particles were less than 220 nm in size, but could still be potentially captured using a low molecular weight ultrafiltration membrane.In the second phase of this research, the potential of activated alumina for removing silica from aqueous solution was studied. Equilibrium, kinetics, and column study were performed to investigate the silica removal efficiency of activated alumina. pH studies showed that a pH of 8.8 is optimum for removal of silica using activated alumina. The equilibrium data fits the well-known Langmuir and Freundlich isotherms. The maximum monolayer adsorption capacity was found to be 17.63 mg/g at pH 8.8. A second order kinetic model fitted the experimental data better than a first order model. Analysis of the kinetic data with Weber-Morris intraparticle diffusion model suggests both external and internal mass transfer controls the overall adsorption process. It was also found that as initial silica concentration increases, external mass transfer becomes important and cannot be ignored in the overall mass transfer process. From the continuous column study, it was surprising to find that feed flow rate did not affect the overall performance of the column between 1 mL/min (2.25 bed volume/hr) and 4.2 mL/min (9.65 bed volume/hr).This th...

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Modeling the kinetics of silica nanocolloid formation and precipitation in geologically relevant aqueous solutions

Cited by 79 publications

References 34 publications

Precipitation mechanism of amorphous silica nanoparticles: A simulation approach

Precipitation mechanism of amorphous silica nanoparticles: A simulation approach

Tracing the origin of dissolved silicon transferred from various soil-plant systems towards rivers: a review

Silica Characterization in Coal Seam Gas Water and Its Removal by Activated Alumina

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