Investigations on the semi-batch precipitation of silica

Schlomach, Jan; Kind, Matthias

doi:10.1016/j.jcis.2004.04.051

Cited by 87 publications

(50 citation statements)

References 41 publications

(48 reference statements)

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“…The course of the solubility is shown in Figure S1 that can be found in the Supplementary Material at the end of this publication. For pH < 8, the solubility is constant and very low ( This is due to an equilibrium between the monomeric silicic acid and its deprotonated anion that can be stabilized by water molecules [1,14]. The equilibrium is shifted to the anion with increasing pH.…”

Section: Influence Of Phmentioning

confidence: 99%

“…For pH < 8, the solubility is constant and very low (r cS i(OH) 4 = 2 mmol/L, but it increases dramatically for pH > 8 by several orders of magnitude. This is due to an equilibrium between the monomeric silicic acid and its deprotonated anion that can be stabilized by water molecules [1,14]. The equilibrium is shifted to the anion with increasing pH.…”

Section: Influence Of Phmentioning

confidence: 99%

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Influence of pH, Temperature and Sample Size on Natural and Enforced Syneresis of Precipitated Silica

Wilhelm

Kind

2015

Polymers

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Abstract:The production of silica is performed by mixing an inorganic, silicate-based precursor and an acid. Monomeric silicic acid forms and polymerizes to amorphous silica particles. Both further polymerization and agglomeration of the particles lead to a gel network. Since polymerization continues after gelation, the gel network consolidates. This rather slow process is known as "natural syneresis" and strongly influences the product properties (e.g., agglomerate size, porosity or internal surface). "Enforced syneresis" is the superposition of natural syneresis with a mechanical, external force. Enforced syneresis may be used either for analytical or preparative purposes. Hereby, two open key aspects are of particular interest. On the one hand, the question arises whether natural and enforced syneresis are analogous processes with respect to their dependence on the process parameters: pH, temperature and sample size. On the other hand, a method is desirable that allows for correlating natural and enforced syneresis behavior. We can show that the pH-, temperature-and sample size-dependency of natural and enforced syneresis are indeed analogous. It is possible to predict natural syneresis using a correlative model. We found that our model predicts maximum volume shrinkages between 19% and 30% in comparison to measured values of 20% for natural syneresis.

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Section: Influence Of Phmentioning

confidence: 99%

Section: Influence Of Phmentioning

confidence: 99%

Influence of pH, Temperature and Sample Size on Natural and Enforced Syneresis of Precipitated Silica

Wilhelm

Kind

2015

Polymers

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“…In the following, these simulation results are compared with the experiment of Schlomach and Kind [22]. Figure 6 shows data from a stirred vessel experiment [22], along with the MC simulation of Schlomach (2006) [40] and the simulated data (LJ) computed here. The fractal dimension is plotted as a function of the time after the gelation point.…”

Section: Consolidation Of a Single Clustermentioning

confidence: 99%

“…Figure 6. Experimental data of the fractal dimension vs. time after gelation point [22] (rhombi) along with the fractal dimension computed in the MC [40] resp. MD simulations (curves).…”

Section: Consolidation Of a Single Clustermentioning

confidence: 99%

“…The consolidation of a gel fragment is computed and compared with experimental data and a former MC simulation of Schlomach and Kind (2007). The temporal development of the structural factor that is measured in Schlomach (2004) [22] is only valid for a certain experiment. Since the experimental investigation of the consolidation of microscale gel fragments is difficult, an experiment for quantifying the consolidation of macroscale silica gels was developed by Sahabi and Kind (2011) [23].…”

Section: Introductionmentioning

confidence: 99%

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Experimentally Justified Model-Like Description of Consolidation of Precipitated Silica

Sahabi

Kind

2011

Polymers

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Abstract:Colloidal gels are intermediates in the production of highly porous particle systems. In the production process, the gels are fragmented after their creation. These gel fragments consolidate to particles whose application-technological properties are determined by their size and porosity. A model of the consolidation process is proposed: The consolidation process of a gel fragment is simulated with the Molecular Dynamics (MD) method with the assumption of van der Waals forces in interplay with the thermal motion as driving forces for the consolidation. The simulation results are compared with experimental data and with a Monte Carlo (MC) simulation.

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Investigation of Precipitation of Calcium Carbonate at High Supersaturations

Schlomach¹,

Quarch²,

Kind³

2006

Chem Eng & Technol

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The formation mechanism of precipitated calcium carbonate from aqueous solution under industrial conditions (high supersaturation) was investigated in a semi-batch and in a continuous mixing nozzle process. The influence of potassium hydroxide and magnesium chloride on crystal modification and particle size were investigated in both processes. Rheological properties of the magnesium stabilized amorphous gel structure have been measured. A similarity between the formation process of calcium carbonate and precipitated silica has been proven.

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Investigations on the semi-batch precipitation of silica

Cited by 87 publications

References 41 publications

Influence of pH, Temperature and Sample Size on Natural and Enforced Syneresis of Precipitated Silica

Influence of pH, Temperature and Sample Size on Natural and Enforced Syneresis of Precipitated Silica

Experimentally Justified Model-Like Description of Consolidation of Precipitated Silica

Investigation of Precipitation of Calcium Carbonate at High Supersaturations

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