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Retardation Behavior of Hydration of Calcium Sulfate Hemihydrate (Bassanite) Induced by Sodium Trimetaphosphate (STMP)


The intermediate bassanite sub-micro crystals were isolated through the introduction of sodium trimetaphosphate (STMP) during the hydration process of bulk bassanite. The precipitated particle size and morphology were firstly checked by the scanning electron microscopy (SEM), and it was found that the particle size was significantly reduced with an increment of STMP, and the majority of the precipitation with >80 mM STMP adding level became sub-micro size. Detailed crystal size was determined by atomic force microscopy (AFM) to be the length of ~1 μm, the height of ~150 nm and the width of ~300nm. The surface structural information at the molecular level was then characterized by the Diffuse Reflectance Infrared Fourier Transform (DRIFT). Afterwards, the crystal structure evolution with different amount of STMP was determined by wide angle X-ray diffraction (WAXD). Both analytical results show the final precipitated sub-micro rods (100 mM STMP) is almost all bassanite rather than gypsum. Moreover, the multi-peak deconvolution of WAXD presents a quantitive analysis of the weight percent of bassanite in final precipitation. The final concentration of bassanite is close to 100% (100 mM STMP). Based on these results, it is proposed that the hydration process of bulk basanite can be described as the dissolution of original bulk bassanite, the formation of bassanite sub-micro rods, and finally the self-assembly of sub-micro rods along c-axis to form gypsum micro-crystal without the additive.

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Publication details

The article was received on 12 Dec 2017, accepted on 02 Feb 2018 and first published on 02 Feb 2018

Article type: Paper
DOI: 10.1039/C7CE02144E
Citation: CrystEngComm, 2018, Accepted Manuscript
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    Retardation Behavior of Hydration of Calcium Sulfate Hemihydrate (Bassanite) Induced by Sodium Trimetaphosphate (STMP)

    W. Chen, Y. Wu, B. Zhang, Y. Wang, F. Li and Z. Qi, CrystEngComm, 2018, Accepted Manuscript , DOI: 10.1039/C7CE02144E

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