Rapid synthesis of alpha calcium sulfate hemihydrate whiskers in glycerol-water solution by using flue-gas-desulfurization gypsum solid waste

Teng, Weili; Wang, Jinshu; Wu, Junshu; Du, Yukou; Jia, Xinjian; Li, Hongyi; Wang, Tianning

doi:10.1016/j.jcrysgro.2018.05.008

Cited by 23 publications

(5 citation statements)

References 42 publications

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“…Controlling the morphology of micro/nanosized inorganic materials has attracted intensive interest because in many cases, it allows one to fine-tune properties with a greater versatility than can be achieved by controlling size, crystallinity, and other parameters. − For instance, as it has been predicted by theoretical calculations and confirmed by experimental work, the catalytic performance can be easily tuned by controlling the morphology of inorganic catalysts. − As an important class of cementitious minerals, α-calcium sulfate hemihydrate (α-CaSO 4 ·0.5H 2 O, α-HH) is widely used in cement, , fertilizers, road-building materials, and so on. Up to the present, much more attention has been paid to the crystal habit control of α-HH crystals − because most of their properties, such as mechanical strength, filtration rate, stability, and so on, are closely associated with the crystal habit. For example, α-HH whiskers and rods have been used as reinforcing agents in polymer and ceramic composites because of their good thermal stability and compatibility, while the α-HH crystals with a low aspect ratio or spherical shape possess better injectability and mechanical properties after hydration .…”

Section: Introductionmentioning

confidence: 99%

Single-Crystal Regular Hexagonal Microplates of Two-Dimensional α-Calcium Sulfate Hemihydrate Preparation from Phosphogypsum in Na₂SO₄ Aqueous Solution

Sun

Wang

et al. 2020

Ind. Eng. Chem. Res.

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Large quantities of solid waste phosphogypsum (PG) not only occupy the farmland but also cause severe pollution to the surrounding environment. The most effective way to achieve a high-value utilization of PG is to prepare α-calcium sulfate hemihydrate (α-HH) with various morphologies. In this study, we developed a simple and Cl-free one-pot synthetic strategy to effectively transform PG into single-crystal α-HH regular hexagonal microplates (RHMPs) in Na 2 SO 4 aqueous solution at 98 °C assisted with sodium citrate (TSC). Na 2 SO 4 plays a role in accelerating the transformation rate, whereas TSC regulates the crystal habit of α-HH from rod to regular hexagonal plate. The rate of DH−α-HH transformation in aqueous solutions can be effectively controlled by regulating water activity (α H 2 O ), which decreases with the increase in Na 2 SO 4 concentration. Crystal habit control is attributed to the strong preferential adsorption of citrate ions to the ( 001) and ( 002) top facets of α-HH by chemical adsorption. The paste made from the obtained α-HH RHMPs deserves higher dry compressive/bending strength of 46.1/15.2 MPa, which is comparable with that of α-HH prepared by other methods. Our work provides a simple and low-corrosiveness strategy to transform PG into α-HH RHMPs with excellent mechanical property, thus showing great promise for a wide range of challenging reuse of solid waste in environmental protection.

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Section: Introductionmentioning

confidence: 99%

Single-Crystal Regular Hexagonal Microplates of Two-Dimensional α-Calcium Sulfate Hemihydrate Preparation from Phosphogypsum in Na₂SO₄ Aqueous Solution

Sun

Wang

et al. 2020

Ind. Eng. Chem. Res.

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“…Like IPA, even if the L-Glu contains two COOH, it cannot regulate the crystal habit of α-CaSO 4 •0.5H 2 O from acicular crystal to short columnar crystal when the two COOH are separated by more than two methylene/methine groups. Inversely, Teng et al [27] synthesized α-CaSO 4 •0.5H 2 O whiskers with high aspect ratios of 200 at atmospheric pressure with the assistance of L-Glu. Therefore, the L-Glu is unable to convert the morphology of α-CaSO 4 •0.5H 2 O from needle-like shape to a short columnar shape.…”

Section: Effect Of Amino Acid On the Crystal Habit Of α-Caso4• 05h2omentioning

confidence: 99%

Effect of Molecular Structure of Organic Acids on the Crystal Habit of α-CaSO4·0.5H2O from Phosphogypsum

Zhang

2020

Crystals

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The organic acid crystal modifiers play an important role in the control of the crystal habit of α-hemihydrate gypsum (α-CaSO4·0.5H2O) from phosphogypsum, but the molecular structure characteristics of crystal modifiers have not been clarified, which makes it difficult to judge whether an organic acid has the ability to regulate the crystal habit of α-CaSO4·0.5H2O directly. In this work, the effect of organic acids with different molecular structures on the crystal habit of α-CaSO4·0.5H2O and its adsorption differences onto the α-CaSO4·0.5H2O surface were explored. The results show that the molecular structure characteristics of crystal modifiers contain two or more carboxylic groups (COOH) that are separated by two methylene or methine groups. Furthermore, organic acids with the regulation ability can adsorb on the surface of α-CaSO4·0.5H2O and change its growth habit. With the increase in the crystal modifier concentration, the α-CaSO4·0.5H2O crystals are shortened in length and enlarged in width, resulting in the decrease in aspect ratio and the increase in compressive strength. Conversely, when the adsorption of ineffective organic acids on the surface of α-CaSO4·0.5H2O was not detected, the α-CaSO4·0.5H2O crystals remained long hexagonal prisms. These results have guiding significance for the screening of novel organic acid crystal modifiers.

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“…As a result, several researchers have started to make calcium sulfate whiskers using the industrial byproduct gypsum as a raw material. Teng prepared calcium sulfate whiskers in an aqueous glycerol–aqueous solution using flue gas desulfurization gypsum as raw material . Wang synthesized calcium sulfate whiskers by the hydrothermal method using phosphogypsum as raw material .…”

Section: Introductionmentioning

confidence: 99%

“…Teng gas desulfurization gypsum as raw material. 14 Wang synthesized calcium sulfate whiskers by the hydrothermal method using phosphogypsum as raw material. 15 The preparation of high value−added calcium sulfate whiskers using industrial byproduct gypsum as raw materials is of great significance for saving resources and protecting the environment.…”

Section: ■ Introductionmentioning

confidence: 99%

Recovery of Tungsten in the Process of Preparation of Calcium Sulfate Whiskers from Scheelite Decomposed Residue

Liu

Zhai

Chen

et al. 2022

ACS Sustainable Chem. Eng.

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When treating complex co–associated low–grade scheelite with sulfur and phosphorus mixed acid co–decomposition techniques, the deterioration in tungsten resource endowment can result in significantly lower decomposition rates, with tungsten content in the decomposition residue (gypsum residue) as high as 2%. In this paper, it is envisaged that by dissolving the gypsum residue in hydrochloric acid to separate it from insoluble tungsten and then regulating the supersaturation of calcium sulfate in the hydrochloric acid solution to prepare calcium sulfate whiskers, not only can the tungsten in the decomposition residue be recovered but also the resource utilization of gypsum can be realized. The effect of Fe3+, Na+, and NH4 + on the crystallization process and morphology of calcium sulfate whiskers was investigated using atmospheric pressure acidification. When the addition amount of gypsum residue was 5.75 g/100 mL, the concentration of hydrochloric acid was 100 g/L, the stirring rate was 100 rpm, the addition amount of NaCl was 30 g/L, the temperature was reduced from 80 to 50 °C, and the L/D ratio of calcium sulfate whiskers could reach 48. The effect of mother liquor circulation on the morphology of calcium sulfate whiskers was also investigated, and the morphology of calcium sulfate whiskers was still good after 10 cycles. During the cycling process, tungsten could be enriched in the residue, and the residue tungsten content could be increased from 3 to 14%.

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Rapid synthesis of alpha calcium sulfate hemihydrate whiskers in glycerol-water solution by using flue-gas-desulfurization gypsum solid waste

Cited by 23 publications

References 42 publications

Single-Crystal Regular Hexagonal Microplates of Two-Dimensional α-Calcium Sulfate Hemihydrate Preparation from Phosphogypsum in Na₂SO₄ Aqueous Solution

Single-Crystal Regular Hexagonal Microplates of Two-Dimensional α-Calcium Sulfate Hemihydrate Preparation from Phosphogypsum in Na₂SO₄ Aqueous Solution

Effect of Molecular Structure of Organic Acids on the Crystal Habit of α-CaSO4·0.5H2O from Phosphogypsum

Recovery of Tungsten in the Process of Preparation of Calcium Sulfate Whiskers from Scheelite Decomposed Residue

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Rapid synthesis of alpha calcium sulfate hemihydrate whiskers in glycerol-water solution by using flue-gas-desulfurization gypsum solid waste

Cited by 23 publications

References 42 publications

Single-Crystal Regular Hexagonal Microplates of Two-Dimensional α-Calcium Sulfate Hemihydrate Preparation from Phosphogypsum in Na2SO4 Aqueous Solution

Single-Crystal Regular Hexagonal Microplates of Two-Dimensional α-Calcium Sulfate Hemihydrate Preparation from Phosphogypsum in Na2SO4 Aqueous Solution

Effect of Molecular Structure of Organic Acids on the Crystal Habit of α-CaSO4·0.5H2O from Phosphogypsum

Recovery of Tungsten in the Process of Preparation of Calcium Sulfate Whiskers from Scheelite Decomposed Residue

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Single-Crystal Regular Hexagonal Microplates of Two-Dimensional α-Calcium Sulfate Hemihydrate Preparation from Phosphogypsum in Na₂SO₄ Aqueous Solution

Single-Crystal Regular Hexagonal Microplates of Two-Dimensional α-Calcium Sulfate Hemihydrate Preparation from Phosphogypsum in Na₂SO₄ Aqueous Solution