The kinetics of dissolution of slaked lime

Giles, Dion E.; Ritchie, I.M.; Xu, Bingan

doi:10.1016/0304-386x(93)90061-h

Cited by 52 publications

(29 citation statements)

References 2 publications

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“…33,34 However, in the presence of certain macromolecules, like natural glycoproteins and polysaccharides or synthetic polymers and even magnesium ions, ACC can be stabilized due to inhibition of its dissolution. 35,36 Giles et al 37 found that the dissolution of Ca(OH) 2 at low stirring rate is controlled by the diffusion of calcium and hydroxide ions away from the surface, while the dissolution is surface controlled at an intensive stirring. Since it is generally accepted that polysaccharides adsorb on mineral surfaces through hydrogen bonds or chemical complexation process in which C-2, C-3 and C-6 hydroxyl groups play crucial roles, [38][39][40] the inhibition of Ca(OH) 2 dissolution is likely to occur.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Calcium Carbonate by Semicontinuous Carbonation Method in the Presence of Dextrans

Kontrec¹,

Ukrainczyk²,

Babić-Ivančić³

et al. 2011

Croat. Chem. Acta

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Abstract. Precipitated calcium carbonate (PCC) was prepared by means of semicontinuous carbonation of Ca(OH) 2 suspension, at 35 and 45 °C and in the presence of non-ionic dextran and dextran sulfate. The carbonation process was regulated at different predetermined values of electrical conductivity, that corresponded to different concentrations of dissolved Ca(OH) 2 : 0.5 mS cm. The results of physicalchemical characterization of the product showed that calcite was the only polymorphic modification obtained in the whole range of experimental conditions investigated. In addition, it was found that morphology, crystal size distribution and specific surface area of PCC strongly depended on the electrical conductivity / concentration of dissolved Ca(OH) 2 , at which the process was performed: predominantly scalenohedral crystals of higher surface area (about 5 m 2 g −1) were produced at higher electrical conductivity, while at lower electrical conductivity predominantly rhomohedral calcite crystals of relatively low specific surface area were obtained. In the system of the highest electrical conductivity, κ 25 = 5.0 mS cm, and at 35 °C, the addition of non-ionic dextran significantly influenced the process by preventing the regulation. The crystals that appeared were in the form of irregular aggregates of high specific surface area, S ≈ 29 m 2 g −1. FT-IR and TG analyses indicated that the non-ionic dextran was adsorbed onto the calcite surface, most probably by relatively strong and specific interactions between oxygen from the hydroxyl groups of dextran molecules and calcium ions from the crystal surface. On the contrary, the anionic dextran (dextran sulfate) exerted minor effects in the course of semicontinuous carbonation process and in the properties of the final product, PCC. However, the analysis of the precipitate indicated that dextran sulfate was adsorbed at the surfaces, most probably by the weak and non-specific electrostatic interactions. (doi: 10.5562/cca1746)

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Section: Resultsmentioning

confidence: 99%

Synthesis of Calcium Carbonate by Semicontinuous Carbonation Method in the Presence of Dextrans

Kontrec¹,

Ukrainczyk²,

Babić-Ivančić³

et al. 2011

Croat. Chem. Acta

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“…On the experimental (continuum) scale, the rate of portlandite dissolution is generally observed to be controlled by transport (Giles et al, 1993;Wang et al, 1998;Johannsen and Rademacher, 1999;Shih et al, 1999;Galan et al, 2011). In the BRNS reactor however, surface reaction controlled kinetics are required, since pore scale diffusive and advective transport is already explicitly taken into account in the MDPN part of the model.…”

Section: Reaction Kinetics and Equilibriamentioning

confidence: 94%

“…In the BRNS reactor however, surface reaction controlled kinetics are required, since pore scale diffusive and advective transport is already explicitly taken into account in the MDPN part of the model. Rotating disc type dissolution experiments provide transport independent portlandite dissolution rates (k p ) of about 5.5 × 10 − 4 mol m −2 s −1 at 25 • C (Giles et al, 1993;Wang et al, 1998). Unfortunately, to our knowledge all apparent activation energies published were obtained under transport controlled conditions and thus include the temperature dependence of diffusion.…”

Section: Reaction Kinetics and Equilibriamentioning

confidence: 96%

Pore-scale modeling of reactive transport in wellbore cement under CO2 storage conditions

Raoof

Nick

Wolterbeek

et al. 2012

International Journal of Greenhouse Gas Control

103

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“…The possible formation of the CaCO 3 coating on the Portlandite crystals [10,11] can however, act as a barrier and hinder further Portlandite dissolution. In this regard, it may also be possible that the dissolution of Ca(OH) 2 may be partially diffusion-controlled [31]. Thus, the kinetically limited dissolution of Portlandite, specially under conditions of accelerated carbonation, may be the reason why the pH of the pore solution initially decreased down to pH ≈12 before it increased and remained constant at pH ≈12.5 (Fig.…”

Section: Discussion 4 Ph Evolution During Carbonation Process-41 Thementioning

confidence: 99%

PH-monitoring in mortar with thermally-oxidized iridium electrodes

2017

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The pH of the concrete pore solution plays a vital role in protecting the reinforcing steel from corrosion. Here, we present results from embeddable pH sensors that permit the continuous, in-situ monitoring of the pH in the concrete pore solution. These are potentiometric sensors, based on thermallyoxidized iridium/iridium oxide (IrO x ) electrodes. We propose an iterative calculation algorithm taking into account diffusion potentials arising from pH changes, thus permitting the reliable, non-destructive determination of the pore solution pH over time. This calculation algorithm forms an essential part of the method using IrO x electrodes. Mortar samples were exposed to accelerated carbonation and the pH was monitored at different depths over time. Comparative tests were also performed using thymolphthalein pH-indicator. The results from the pH sensors give insight in the carbonation process, and can, in contrast to thermodynamic modelling and titration experiments, provide insight in kinetic processes such as transport and phases transformations. It was found that the front at which the pH is decreased from initially 13-14 down to 12.5 can be significantly ahead of the common carbonation front corresponding to pH 9-10. This has major implications for laboratory testing and engineering practice.

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The kinetics of dissolution of slaked lime

Cited by 52 publications

References 2 publications

Synthesis of Calcium Carbonate by Semicontinuous Carbonation Method in the Presence of Dextrans

Synthesis of Calcium Carbonate by Semicontinuous Carbonation Method in the Presence of Dextrans

Pore-scale modeling of reactive transport in wellbore cement under CO2 storage conditions

PH-monitoring in mortar with thermally-oxidized iridium electrodes

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