Transformation of flue gas desulfurization (FGD) gypsum to β-CaSO4·0.5H2O whiskers using facile water treatment

Abstract

A novel way for transformation of flue gas desulfurization (FGD) gypsum, an industrial by-product to β-CaSO4·0.5H2O whiskers is investigated for calcium sulfate rich alternative construction material. As the consumption of gypsum products is increasing in construction industry and limited amount of natural gypsum is available, herein facile water treatment is used to generate fine tubular particles by recrystallization and growth of β-CaSO4·0.5H2O without any chemical for the first time. Remarkable properties of FGD gypsum are characterized with mean particle size of 42.875–48.759 µm, bulk density of 1.08–1.21 g/cm3 and specific gravity of 3.06–3.35. XRD, FTIR, WD-XRF, FESEM-EDS and HR-TEM analysis confirm the composition and morphology of the synthesized material. XRD pattern of treated FGD gypsum confirms the presence of highly crystalline β-CaSO4·0.5H2O. FESEM micrographs confirm the micro-needle type morphology with very high aspect ratio of 25:1.Results showed that magnetic stirring improves the removal efficacy of impurities. This study will open the perspective for development of FGD gypsum whiskers with very high aspect ratio and will pave the way for future investigation for a green alternate of natural gypsum for construction applications.