Effect of glycerol on the preparation of phosphogypsum-based CaSO4·0.5H2O whiskers

Abstract

Phosphogypsum-based CaSO4·0.5H2O whiskers were successfully prepared in the presence of glycerol by hydrothermal method. The action mechanism of glycerol on the morphology of CaSO4·0.5H2O whiskers was investigated and discussed in detail. The as-prepared products were characterized by X-ray powder diffraction spectrometer, scanning electron microscopy, Fourier transform infrared spectrometer, and thermal analyzer. The main phase of the as-prepared products was CaSO4·0.5H2O, and the morphology was uniform fiber. Moreover, the aspect ratio and productivity of the as-prepared CaSO4·0.5H2O whiskers increased with the concentration of glycerol. Even whiskers with mean length of 38–83 μm, mean width of 1.33–0.73 μm, aspect ratio of 29–118, and productivity of 89–96 % were obtained under the condition of glycerol/water volume ratio of 10–100 %. As far as mechanism was concerned, the hydroxyl groups of glycerol adsorbed and occupied the vacancies of Ca sites on (001) plane of CaSO4·0.5H2O whiskers, and however, on (100) plane, hydroxyl groups of glycerol adsorbed mainly on Ca sites and formed hydrogen bond layered structure on both sides of that, which should be the reason that CaSO4·0.5H2O whiskers grew along the c-axis observed in this study.