Effect of CuCl<sub>2</sub> on hydrothermal crystallization of calcium sulfate whiskers prepared from FGD gypsum

Wang, Xiao; Jin, Biao; Yang, Liu; Zhu, Xiao

doi:10.1002/crat.201500035

Cited by 23 publications

(15 citation statements)

References 28 publications

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“…Meanwhile, in order to improve the aspect ratios of crystal products, crystal modifiers preferentially adsorbed on the side facets of the crystals, tend to be added into the crystallization reaction system. For example, metal ions such as Mg 2+ 16 , 19 , Cu 2+ 28 , Al 3+ 29 , can increase the aspect ratios of the whiskers dramatically from dozens to hundreds, and some organic additives, such as cetyltrimethyl ammonium bromide (CTAB) 25 , 27 and ethylene glycol 18 , can also produce α-HH whiskers with the aspect ratio up to hundreds.…”

Section: Introductionmentioning

confidence: 99%

A facile method of transforming FGD gypsum to α-CaSO4·0.5H2O whiskers with cetyltrimethylammonium bromide (CTAB) and KCl in glycerol-water solution

Guan

Sun

et al. 2017

Sci Rep

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A facile method to transform flue gas desulfurization gypsum (FGD gypsum) to α- calcium sulfate hemihydrate (α-HH) whiskers with high aspect ratios mediated by cetyltrimethylammonium bromide (CTAB) and KCl in glycerol-water solutions was studied. Addition of KCl facilitated the dissolution of calcium sulfate dihydrate (DH) and created a much higher supersaturation, which could come into being a larger driving force for the phase transformation from DH to α-HH. CTAB as the crystal modifier can significantly promoted 1-D growth of α-HH whiskers along the c axis and the presence of 0.25% CTAB (by weight of FGD gypsum) resulted in the increase of the average aspect ratio of α-HH whiskers from 28.9 to 188.4, which might be attributed to the preferential adsorption of C16H33(CH3)3N+ on the negative side facets of α-HH crystal.

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Section: Introductionmentioning

confidence: 99%

A facile method of transforming FGD gypsum to α-CaSO4·0.5H2O whiskers with cetyltrimethylammonium bromide (CTAB) and KCl in glycerol-water solution

Guan

Sun

et al. 2017

Sci Rep

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“…Generally, CSHW with smaller diameter and higher aspect ratio can achieve excellent performance [ 7 ]. However, the diameter of the present CSHW can only achieve micrometer scale with a relatively low aspect ratio [ 8 ].…”

Section: Introductionmentioning

confidence: 99%

Preparation of CSHW with Flue Gas Desulfurization Gypsum

Gao

et al. 2022

Materials

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Calcium sulfate hemihydrate whiskers (CSHW), a multi-functional and high value-added building material, were prepared with flue gas desulfurization (FGD) gypsum by hydrothermal method, which could be a reasonable disposal of FGD gypsum. In order to obtain CSHW of a high aspect ratio, a series of manufacturing parameters such as reaction temperature, stirring speed, material–water ratio, and reaction time were investigated. The effect of stabilizing treatment and glycerol concentration on CSHW morphology were also studied by environmental scanning electron microscopy (ESEM) and statistical analysis. The results showed that the optimum preparing conditions of reaction temperature, stirring speed, water–material ratio, and reaction time were 160 °C, 200~300 rpm, 11:1 and 1 h, respectively. Furthermore, stabilizing treatment with octodecyl betaine was necessary for the preparation of CSHW. The final prepared whiskers had smooth surface, uniform morphology, a diameter of 260 nm, and a corresponding aspect ratio of 208.2. Moreover, the addition of glycerol reduced the activity of water, contributing to a lower reaction temperature and much smaller diameter.

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“…Utilization of the flue gas desulfurization (FGD) gypsum (mainly composed of CaSO 4 ·2H 2 O, DH) to prepare high value-added α-calcium sulfate hemihydrate (α-CaSO 4 ·0.5H 2 O, α-HH) is of great significance to environmental protection as well as natural gypsum resource conservation. , α-HH with different morphologies such as hexagonal prism, whisker, nanorod, sphere, and ellipsoid are synthesized for exploiting morphology/structure-directed physicochemical properties and applications. − The whiskers of α-HH prove to be useful reinforcing agents in polymer and ceramic composites due to their good thermal properties and compatibility. − Herein, preparation of α-HH whiskers with high aspect ratios from FGD gypsum attracts great interest. − …”

Section: Introductionmentioning

confidence: 99%

Sodium Cation-Mediated Crystallization of α-Hemihydrate Whiskers from Gypsum in Ethylene Glycol–Water Solutions

Huang

Shen

et al. 2018

Crystal Growth & Design

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This work reports a facile sodium cation (Na+)-mediated approach to synthesize α-calcium sulfate hemihydrate (α-HH) whiskers, with calcium sulfate dihydrate (DH) as the precursor, in ethylene glycol (EG)–water solutions at 95.0 °C and atmospheric pressure. The as-synthesized α-HH whiskers exhibit a width of 3–5 μm and a length of 600–700 μm, showing highly promising applications as reinforcing agents. An EG volume percentage of 22.5 vol % is necessary to drive the conversion of DH to α-HH at 95.0 °C, while the Na+ plays a crucial role in regulating both the conversion kinetics and the whisker quality. The conversion rate presents a volcano-like variation versus Na+ concentration (0.05–0.30 M) with the peak one achieved at 0.10 M Na+. Simultaneous boosting and retarding effects of the metallic cation on the DH-α-HH transformation were reported for the first time in alcohol–water systems. The tuning role of Na+ arises from its effect on the supersaturation for α-HH nucleation, the surface property of precursor DH via Na+ doping, as well as surface precipitate of the solid solution eugsterite (Na4Ca(SO4)3·2H2O). In shape control, an increased Na+ concentration can elongate the α-HH but simultaneously raise the possibility of whisker agglomeration. The bridging action of Na+ among the crystal interfaces associated with the α-HH nucleation accounts for the morphology evolution of whiskers, and the optimal Na+ concentration is 0.075 M with an average aspect ratio of 105. This work provides a systematical investigation on the cation-mediated crystallization of α-HH whiskers, which should lead to a deeper understanding of whisker formation and advance their scale applications.

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Effect of CuCl₂ on hydrothermal crystallization of calcium sulfate whiskers prepared from FGD gypsum

Cited by 23 publications

References 28 publications

A facile method of transforming FGD gypsum to α-CaSO4·0.5H2O whiskers with cetyltrimethylammonium bromide (CTAB) and KCl in glycerol-water solution

A facile method of transforming FGD gypsum to α-CaSO4·0.5H2O whiskers with cetyltrimethylammonium bromide (CTAB) and KCl in glycerol-water solution

Preparation of CSHW with Flue Gas Desulfurization Gypsum

Sodium Cation-Mediated Crystallization of α-Hemihydrate Whiskers from Gypsum in Ethylene Glycol–Water Solutions

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Effect of CuCl2 on hydrothermal crystallization of calcium sulfate whiskers prepared from FGD gypsum

Cited by 23 publications

References 28 publications

A facile method of transforming FGD gypsum to α-CaSO4·0.5H2O whiskers with cetyltrimethylammonium bromide (CTAB) and KCl in glycerol-water solution

A facile method of transforming FGD gypsum to α-CaSO4·0.5H2O whiskers with cetyltrimethylammonium bromide (CTAB) and KCl in glycerol-water solution

Preparation of CSHW with Flue Gas Desulfurization Gypsum

Sodium Cation-Mediated Crystallization of α-Hemihydrate Whiskers from Gypsum in Ethylene Glycol–Water Solutions

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Product

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Effect of CuCl₂ on hydrothermal crystallization of calcium sulfate whiskers prepared from FGD gypsum