Theory of the von Weimarn rules governing the average size of crystals precipitated from a supersaturated solution

Barlow, Douglas A.; Baird, James K.; Su, Ching‐Hua

doi:10.1016/j.jcrysgro.2003.12.047

Cited by 79 publications

(62 citation statements)

References 15 publications

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“…To put the overall behavior of growth rate with increasing supersaturation (molar inflow rate) into perspective, von Weimarn's second law may be recalled. This law, which was first described in the early twentieth century and later confirmed by experiments and theoretically [48][49][50], states that for a given crystallization time the average particle size passes through a maximum as a function of initial supersaturation [50]. In the present study the employed mode of reagent inflow resulted in a nearly constant supersaturation environment that is comparable with the initial supersaturation situation in a batch experiment.…”

Section: Figure 4: Influence Of Reagent Inflow Rate On Crystal Size Dsupporting

confidence: 75%

The crystal growth kinetics of alpha calcium sulfate hemihydrate in concentrated CaCl2–HCl solutions

Feldmann

Demopoulos²

2012

Journal of Crystal Growth

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The crystal growth kinetics of calcium sulfate α-hemihydrate (α-HH) in nearly constant supersaturated HCl-CaCl 2 solutions were investigated. Two types of solutions were used, the first had a low HCl (1.4 mol/L) and high CaCl 2 (2.8 mol/L) concentration and the second had a high HCl (5.6 mol/L) and low CaCl 2 (0.7 mol/L) concentration. These conditions were chosen to represent the first and last stage of a newly developed stage-wise HCl regeneration process. The seeded growth experiments were carried out in a stirred, temperature controlled semi-batch reactor in which supersaturation was kept constant by simultaneous addition of CaCl 2 and Na 2 SO 4 solutions. The influence of the following parameters on α-HH crystal growth was studied: temperature (70-95°C), specific power input of stirring (0.02-1.29 W/kg) and equimolar inflow rate of CaCl 2 and Na 2 SO 4 (0-0.6 mol/h). The crystal growth rate was derived from particle size distribution measurements made with the laser light diffraction technique. It was found that the surface area normalized crystal growth rate increased linearly with the molar inflow rate up to 0.3 mol/h, at higher inflow rates no further increase of the growth rate was observed. Temperature and specific power input, within the investigated ranges, did not show a marked effect on the growth rate, attributable to a diffusion/adsorption controlled growth process. An interesting finding of the present research is the establishment of a positive relationship between the narrowing of the width of the particle size distribution with increasing crystal growth rate. The results show that the resulting particle size distribution is positively related to the reagent inflow rate, a finding that can be applied to the industrial design and scale-up of the α-HH crystallization/HCl regeneration process.

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Section: Figure 4: Influence Of Reagent Inflow Rate On Crystal Size Dsupporting

confidence: 75%

The crystal growth kinetics of alpha calcium sulfate hemihydrate in concentrated CaCl2–HCl solutions

Feldmann

Demopoulos²

2012

Journal of Crystal Growth

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“…This is an interesting result in that it predicts that the maximum value for J can be for some s other than at s(0), unlike the previously mentioned studies [1,2] where the model used for J always gives the maximum value at s(0). The maximum value for J as given by Eq.…”

Section: Theorymentioning

confidence: 63%

“…Unfortunately, these expressions for the distribution function and time-dependent supersaturation are cumbersome and difficult to compare with experimental data. One group has since studied how the mean crystal size given by this distribution function depends upon initial concentration and the nucleation rate [2]. This sizedistribution function has also been used to predict how initial undercooling might relate to the equilibrium grain size in certain metals [3].…”

Section: Introductionmentioning

confidence: 99%

Theory of the intermediate stage of crystal growth with applications to protein crystallization

Barlow

2009

Journal of Crystal Growth

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“…The starting time and supersaturation of the ripening stage is given in terms of the initial supersaturation and other known physical parameters. In Section 6, a short summary is given, and the von Weimarn rules [7,8] found experimentally are examined with the present results.…”

Section: Introductionmentioning

confidence: 94%

Transition from nucleation to ripening in the classical nucleation model

Uwaha

Koyama

2010

Journal of Crystal Growth

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Theory of the von Weimarn rules governing the average size of crystals precipitated from a supersaturated solution

Cited by 79 publications

References 15 publications

The crystal growth kinetics of alpha calcium sulfate hemihydrate in concentrated CaCl2–HCl solutions

The crystal growth kinetics of alpha calcium sulfate hemihydrate in concentrated CaCl2–HCl solutions

Theory of the intermediate stage of crystal growth with applications to protein crystallization

Transition from nucleation to ripening in the classical nucleation model

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