The kinetics of crystal growth of calcium sulfate dihydrate

Liu, Sung-Tsuen; Nancollas, G.H.

doi:10.1016/0022-0248(70)90081-3

Cited by 175 publications

(70 citation statements)

References 11 publications

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“…The calcite saturation index computed using these field rates and the Zhang and Dawe laboratory determined rate constants range from 1.51 to 3.28 or 0.18 < log X < 0.51 which is closely consistent with the bulk of the saturation indexes listed in Fig. 5 Gypsum dissolution and/or precipitation rates have been reported by Liu and Nancollas (1970), Brandse et al (1977), Christoffersen et al (1982), Brant and Bosbach (2001), and Jeschke et al (2001). These studies suggest that gypsum growth rates are consistent with Eq.…”

Section: Comparison Of Field Based With Laboratory Measured Precipitasupporting

confidence: 72%

Mineral precipitation rates during the complete evaporation of the Merouane Chott ephemeral lake

Hacini

Kherici

Oelkers

2008

Geochimica et Cosmochimica Acta

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Section: Comparison Of Field Based With Laboratory Measured Precipitasupporting

confidence: 72%

Mineral precipitation rates during the complete evaporation of the Merouane Chott ephemeral lake

Hacini

Kherici

Oelkers

2008

Geochimica et Cosmochimica Acta

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“…As described elsewhere (1,4,16) the seeded crystal growth of a sparingly soluble salt provides a sensitive and reproducible technique for the evaluation of inhibitor effects. The technique involves the addition of a fixed amount of seed crystals to a metastable solution of the inorganic salt followed by periodic analysis for changes in the salt concentration.…”

Section: Methodsmentioning

confidence: 99%

Kinetics of crystal growth of calcium sulfate dihydrate. The influence of polymer composition, molecular weight, and solution pH

Amjad¹

1988

Can. J. Chem.

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A seeded crystal growth technique has been used to study the influence of solution pH and temperature ranging from 25 to 50°C on the performance of polymers of varying functional groups as calcium sulfate dihydrate (CaS04.2H20, gypsum) crystal growth inhibitors. Results indicate that at constant temperature and at a constant solution pH, crystallization in the presence of polyacrylic acids is preceded by an initial slow growth reaction, hcreaftcr called induction period, following which crystal growth of gypsum proceeds with a rate close to that in pure supersaturated solution. Results suggest that at a constant pH, polyacrylic acid concentration, molecular weight, and temperature greatly affect the duration of induction period. Kinetic data collected as a function of solution pH in the range 2.5 to 9.0 suggest that solution pH has a marked effect on the induction period. The observed dependence of induction period on solution pH may be explained in terms of the degree of ionization of polyacrylic acid. Among the polymers of varying functional groups studied, i.e. carboxyl, sulfonate, acrylamide, dimethyldiallylammonium, etc., only those polymers having carboxyl group showed marked inhibitory activity for the growth of gypsum crystals.ZAHID AMJAD. Can. J . Chem. 66, 1529 (1988) On a fait appel i une technique de croissance de cristaux ensemencCs pour Ctudier I'influence du pH de la solution ainsi que de la tempkrature (allant de 25 i 50°C) sur la performance de polymkres portant divers groupements fonctionnels comme inhibiteurs de la croissance de cristaux du sulfate de calcium dihydratC (&SO4. 2H20, gypse). Les rCsultats indiquent que, i tempCrature constante et i un pH de solution constant, la cristallisation en prCsence d'acides polyacryliques est prCcCdCe par une rCaction initiale de croissance qui est lente, appelCe par la suite pCriode d'induction, et qui est suivie par une croissanee du cristal de gypse se produisant i une vitesse qui est proche de celle qui est observie avec une solution sursaturke pure. Les rCsultats suggerent que, i des pH constants, la concentration en acide polyacrylique, le poids molCculaire et la tempirature influencent beaucoup la pCriode d'induction. Les donnCes cinCtiques recueillies en fonction du pH allant de 2,5 2 9,O suggtrent que le pH de la solution a une influence marquCe sur la pCriode d'induction. On peut expliquer cette observation en fonction du degri d'ionisation de I'acide polyacrylique. Parmi les polymeres portant divers groupements fonctionnels, eomme carboxyle, sulfonate, acrylamide, dirnithyldiallylammonium, etc, seuls les polymeres portant des groupements carbonyles prisentent une activitC inhibitrice marquee sur la croissance des cristaux de gypse.[Traduit par la revue]

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“…E A /kJ·mol −1 Observations [27] 62.8 Crystallization of gypsum on the addition of seed crystals to stable supersaturated solutions was studied from 15-45 • C.…”

Section: Referencementioning

confidence: 99%

Physicochemical and Additive Controls on the Multistep Precipitation Pathway of Gypsum

et al. 2017

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Synchrotron-based small-and wide-angle X-ray scattering (SAXS/WAXS) was used to examine in situ the precipitation of gypsum (CaSO 4 ·2H 2 O) from solution. We determined the role of (I) supersaturation, (II) temperature and (III) additives (Mg 2+ and citric acid) on the precipitation mechanism and rate of gypsum. Detailed analysis of the SAXS data showed that for all tested supersaturations and temperatures the same nucleation pathway was maintained, i.e., formation of primary particles that aggregate and transform/re-organize into gypsum. In the presence of Mg 2+ more primary particle are formed compared to the pure experiment, but the onset of their transformation/reorganization was slowed down. Citrate reduces the formation of primary particles resulting in a longer induction time of gypsum formation. Based on the WAXS data we determined that the precipitation rate of gypsum increased 5-fold from 4 to 40 • C, which results in an effective activation energy of~30 kJ·mol −1 . Mg 2+ reduces the precipitation rate of gypsum by more than half, most likely by blocking the attachment sites of the growth units, while citric acid only weakly hampers the growth of gypsum by lowering the effective supersaturation. In short, our results show that the nucleation mechanism is independent of the solution conditions and that Mg 2+ and citric acid influence differently the nucleation pathway and growth kinetics of gypsum. These insights are key for further improving our ability to control the crystallization process of calcium sulphate.

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The kinetics of crystal growth of calcium sulfate dihydrate

Cited by 175 publications

References 11 publications

Mineral precipitation rates during the complete evaporation of the Merouane Chott ephemeral lake

Mineral precipitation rates during the complete evaporation of the Merouane Chott ephemeral lake

Kinetics of crystal growth of calcium sulfate dihydrate. The influence of polymer composition, molecular weight, and solution pH

Physicochemical and Additive Controls on the Multistep Precipitation Pathway of Gypsum

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