The Kinetics of Crystal Growth in Barium Sulfate Precipitation. II. Temperature Dependence and Mechanism.

Nielsen, Arne E.; Takki-Luukkainen, I.-T.; Smith-Kielland, I.; Sömme, R.; Stenhagen, Einar; Palmstierna, H.

doi:10.3891/acta.chem.scand.13-0784

Cited by 54 publications

(18 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Compared to empirical models used in the past (simplified rate equations, the Johnson-Mehl-AvramiKolmogorov model [23][24][25] or the Chronomal approach 26 ), the present formalism fully accounts for all processes possibly taking place at each time step, without assuming that nucleation, growth, and ripening occur sequentially. Since it follows the size variation of all particle classes that have been nucleated, it is able to yield thorough information on the time evolution of the particle population, for example the mean particle size, as well as of the aqueous solution composition.…”

Section: Methodsmentioning

confidence: 99%

“…The net balance nearly exactly vanishes during some period of time as far as the aqueous solution saturation state is concerned, although, when looking carefully at the values of I, one may see that it displays tiny fluctuations on the plateaus (not visible at the scale of Figure 1) . It is clear that precipitation models assuming that nucleation and growth are successive stages [23][24][25][26] (1) would find an immediate decrease of the saturation state of the aqueous solution in the nucleation period, except if they impose the size of critical nuclei to be zero, and (2) would never be able to produce plateaus in the saturation curves. Moreover, precipitation models which do not include Ostwald ripening would not be able either to produce such plateaus.…”

Section: Saturation Plateausmentioning

confidence: 99%

“…It is thus timely to apply an advanced simulation technique to decipher the microscopic mechanism of amor-phous silica precipitation, beyond empirical approaches used in the past, such as simplified rate-equations 4,7,8 , the Johnson-Mehl-Avrami-Kolmogorov model 9,10,[23][24][25] or the Chronomal approach 9,10,26 . In the present computational approach, we demonstrate that use of the classical nucleation theory and of a size dependent growth law, as embedded in the NANOKIN code [27][28][29][30] , allows a quantitative description of precipitation occurring under largely different experimental conditions : pre-established initial supersaturation 4 , supersaturation reached by neutralization of a high-pH silica solution 9 or by fast cooling 10 .…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Precipitation mechanism of amorphous silica nanoparticles: A simulation approach

Noguera

Fritz

Clément

2015

Journal of Colloid and Interface Science

View full text Add to dashboard Cite

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.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Saturation Plateausmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Precipitation mechanism of amorphous silica nanoparticles: A simulation approach

Noguera

Fritz

Clément

2015

Journal of Colloid and Interface Science

View full text Add to dashboard Cite

show abstract

“…Nanoscale barium sulfate (BaSO 4 ) particles are applied in polymer strengthening or in producing composite materials. In production of crystalline thermoplastic materials the fine particles on the base of BaSO 4 are used as nucleation centers.…”

Section: Introductionmentioning

confidence: 99%

“…Angerhöfer [9] examined the nucleus building and growth speed of BaSO 4 nanoparticles for a wide range of supersaturations and stated that integration limited growth, taking place at a low degree of supersaturation. However, a transition to diffusion-limited growth occurs at high degrees of supersaturation [2].…”

Section: Introductionmentioning

confidence: 99%

Optimization of a Continuous Precipitation Process to Produce Nanoscale BaSO4

Pieper

Aman

Hintz

et al. 2011

Chem. Eng. Technol.

View full text Add to dashboard Cite

The effect of supersaturation, reaction temperature, and mixing intensity on particle size was investigated. Sterical stabilization of barium sulfate suspensions was applied to prevent formation of agglomerates. This allowed a reactant ratio of 1:1, thus maximizing product yield. The local supersaturation is strongly affected by the mixing intensity that can be characterized by Reynolds numbers. The significant decrease in particle size was observed by increasing the Reynolds number from 600 to 8000. A higher reactant concentration leads to a higher degree of supersaturation, and finer particles are precipitated. The particle size can be reduced with increasing reactant concentration. The degree of supersaturation increases with temperature reduction, i.e., the particle size will be reduced at low temperature. In addition, nucleation and growth kinetics are changed in a way that reduces the particle size. The optimized lab-scale process is capable of producing over 1 kg h -1 of nanoscaled BaSO 4 with a median diameter of 75 nm.

show abstract

Investigation of the Precipitation of Barium Sulfate Nanoparticles

2008

View full text Add to dashboard Cite

Precipitation is a promising process for nanoparticle production because it is a fast, economic process and simple to design. In the present work, barium sulfate particles were produced by discontinuous precipitation in a stirred tank reactor. Particle sizes of less than 100 nm were achieved. Particle size distributions strongly depend on the mechanical mixing and the molar ratio of the reactants as well as on the stabilization of the particles in the suspension.

show abstract

The Kinetics of Crystal Growth in Barium Sulfate Precipitation. II. Temperature Dependence and Mechanism.

Cited by 54 publications

References 0 publications

Precipitation mechanism of amorphous silica nanoparticles: A simulation approach

Precipitation mechanism of amorphous silica nanoparticles: A simulation approach

Optimization of a Continuous Precipitation Process to Produce Nanoscale BaSO4

Investigation of the Precipitation of Barium Sulfate Nanoparticles

Contact Info

Product

Resources

About