Solubility of α-Calcium Sulfate Hemihydrate in Ca–Mg–K Chloride Salt Solution at (353.0 to 371.0) K

2012 ◽  
Vol 58 (1) ◽  
pp. 48-54 ◽  
Author(s):  
Xiaoqin Wu ◽  
Kemiao Wang ◽  
Zhiyang Xiong ◽  
Xiaoli Ye
Keyword(s):  
Salt Solution ◽  
Calcium Sulfate ◽  
Chloride Salt ◽  
Calcium Sulfate Hemihydrate

Influence of Seed Crystal and Modifier on the Morphology of α-calcium Sulfate Hemihydrate Prepared by Salt Solution Method in Pilot Scale

2010 ◽  
Vol 168-170 ◽  
pp. 8-12
Author(s):  
Bao Kong ◽  
Bao Hong Guan ◽  
Liu Chun Yang
Keyword(s):  
Salt Solution ◽  
Calcium Sulfate ◽  
Solution Method ◽  
Pilot Scale ◽  
Seed Crystal ◽  
Flue Gas Desulfurization ◽  
Fgd Gypsum ◽  
Mixed Salts ◽  
Spherical Crystals ◽  
Calcium Sulfate Hemihydrate

Preparation of α-calcium sulfate hemihydrate (α-HH) from flue gas desulfurization (FGD) gypsum is of great value in effectively utilizing the FGD gypsum. This paper focuses on the effect of seed crystal and some modifiers on the morphology of α-HH on a 500-1000 kg/batch setup based on a salt solution method established on the previous work. The pilot tests were carried out in a Ca-Mg-K chloride solution medium at 94 oC (±2 oC) under atmospheric pressure. The results show that a small amount of seeds is advantageous to prepare short-prism α-HH but results in needle-like and spherical crystals in the case of more than 1% addition. The well-shaped α-HH crystals can also be obtained by adding appropriate amounts of crystal modifiers like Fe3+ and the mixed salts of Al3+ and organics.

Effects of phosphorus impurities on the preparation of α-calcium sulfate hemihydrate from waste phosphogypsum with the salt solution method under atmospheric pressure

CrystEngComm ◽  
2019 ◽  
Vol 21 (16) ◽  
pp. 2631-2640 ◽  
Author(s):  
Yang Mi ◽  
Deyu Chen ◽  
Aiwen Wang
Keyword(s):  
Salt Solution ◽  
Atmospheric Pressure ◽  
Calcium Sulfate ◽  
Solution Method ◽  
Crystallization Process ◽  
Calcium Sulfate Hemihydrate

Impurity is an important factor that determines the crystallization process of α-calcium sulfate hemihydrate (α-CSH), but the effects of phosphorus impurities in waste phosphogypsum on the α-CSH prepared using the salt solution method are still not well known.

Effects of sterilization modes on the mechanical strengths of plaster of paris implants

1989 ◽  
Vol 47 ◽  
pp. 890-891
Author(s):  
K. Cowden ◽  
B. Giammara ◽  
T. Devine ◽  
J. Hanker
Keyword(s):  
Gamma Radiation ◽  
Calcium Sulfate ◽  
Significant Loss ◽  
Potassium Sulfate ◽  
Limiting Factors ◽  
Radiation Sterilization ◽  
Plaster Of Paris ◽  
Hardness Tester ◽  
Dry Heat ◽  
Calcium Sulfate Hemihydrate

Plaster of Paris (calcium sulfate hemihydrate, CaSO4. ½ H2O) has been used as a biomedical implant material since 1892. One of the primary limiting factors of these implants is their mechanical properties. These materials have low compressive and tensile strengths when compared to normal bone. These are important limiting factors where large biomechanical forces exist. Previous work has suggested that sterilization techniques could affect the implant’s strength. A study of plaster of Paris implant mechanical and physical properties to find optimum sterilization techniques therefore, could lead to a significant increase in their application and promise for future use as hard tissue prosthetic materials.USG Medical Grade Calcium Sulfate Hemihydrate Types A, A-1 and B, were sterilized by dry heat and by gamma radiation. Types A and B were additionally sterilized with and without the setting agent potassium sulfate (K2SO4). The plaster mixtures were then moistened with a minimum amount of water and formed into disks (.339 in. diameter x .053 in. deep) in polyethylene molds with a microspatula. After drying, the disks were fractured with a Stokes Hardness Tester. The compressive strengths of the disks were obtained directly from the hardness tester. Values for the maximum tensile strengths σo were then calculated: where (P = applied compression, D = disk diameter, and t = disk thickness). Plaster disks (types A and B) that contained no setting agent showed a significant loss in strength with either dry heat or gamma radiation sterilization. Those that contained potassium sulfate (K2SO4) did not show a significant loss in strength with either sterilization technique. In all comparisons (with and without K2SO4 and with either dry heat or gamma radiation sterilization) the type B plaster had higher compressive and tensile strengths than that of the type A plaster. The type A-1 plaster however, which is specially modified for accelerated setting, was comparable to that of type B with K2SO4 in both compressive and tensile strength (Table 1).

scholarly journals Tetracalcium Phosphate/Monetite/Calcium Sulfate Hemihdrate Biocement Powder Mixtures Prepared by the One-Step Synthesis for Preparation of Nanocrystalline Hydroxyapatite Biocement-Properties and In Vitro Evaluation

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2137
Author(s):  
Lubomir Medvecky ◽  
Maria Giretova ◽  
Radoslava Stulajterova ◽  
Lenka Luptakova ◽  
Tibor Sopcak
Keyword(s):  
Simulated Body Fluid ◽  
Body Fluid ◽  
Calcium Sulfate ◽  
Powder Mixtures ◽  
Liquid Component ◽  
Tetracalcium Phosphate ◽  
Nanocrystalline Hydroxyapatite ◽  
One Step ◽  
Calcium Sulfate Hemihydrate

A modified one-step process was used to prepare tetracalcium phosphate/monetite/calcium sulfate hemihydrate powder cement mixtures (CAS). The procedure allowed the formation of monetite and calcium sulfate hemihydrate (CSH) in the form of nanoparticles. It was hypothesized that the presence of nanoCSH in small amounts enhances the in vitro bioactivity of CAS cement in relation to osteogenic gene markers in mesenchymal stem cells (MSCs). The CAS powder mixtures with 15 and 5 wt.% CSH were prepared by milling powder tetracalcium phosphate in an ethanolic solution of both orthophosphoric and sulfuric acids. The CAS cements had short setting times (around 5 min). The fast setting of the cement samples after the addition of the liquid component (water solution of NaH2PO4) was due to the partial formation of calcium sulfate dihydrate and hydroxyapatite before soaking in SBF with a small change in the original phase composition in cement powder samples after milling. Nanocrystalline hydroxyapatite biocement was produced by soaking of cement samples after setting in simulated body fluid (SBF). The fast release of calcium ions from CAS5 cement, as well as a small rise in the pH of SBF during soaking, were demonstrated. After soaking in SBF for 7 days, the final product of the cement transformation was nanocrystalline hydroxyapatite. The compressive strength of the cement samples (up to 30 MPa) after soaking in simulated body fluid (SBF) was comparable to that of bone. Real time polymerase chain reaction (RT-PCR) analysis revealed statistically significant higher gene expressions of alkaline phosphatase (ALP), osteonectin (ON) and osteopontin (OP) in cells cultured for 14 days in CAS5 extract compared to CSH-free cement. The addition of a small amount of nanoCSH (5 wt.%) to the tetracalcium phosphate (TTCP)/monetite cement mixture significantly promoted the over expression of osteogenic markers in MSCs. The prepared CAS powder mixture with its enhanced bioactivity can be used for bone defect treatment and has good potential for bone healing.

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