A readily monitored and controllable hydrothermal system for the facile, cost-effective transformation of FGD gypsum to calcium sulfate hemihydrate whiskers--颗粒学报PARTICUOLOGY

Cao, B., Wang, X., Zhang, X., Jin, B., Xu, Z., Liu, X., . . . Yang, L. (2021). A readily monitored and controllable hydrothermal system for the facile, cost-effective transformation of FGD gypsum to calcium sulfate hemihydrate whiskers. Particuology, 54, 173-180. https://doi.org/10.1016/j.partic.2020.03.003

A readily monitored and controllable hydrothermal system for the facile, cost-effective transformation of FGD gypsum to calcium sulfate hemihydrate whiskers

Bolun Cao ^a, Xiao Wang ^b, Xiaoting Zhang ^b, Biao Jin ^b, Zhuoyue Xu ^b, Xueping Liu ^b, Wei Zhang ^c, Liushuan Yang ^{a b *}

a College of Materials Science and Engineering, Zhengzhou University, Zhengzhou 410001, China
b School of Materials and Chemical Engineering, Henan University of Urban Construction, Pingdingshan 467036, China
c Zhengzhou Key Laboratory of Water Resource and Environment, Zhengzhou, 450001, China

10.1016/j.partic.2020.03.003

Volume 54, February 2021, Pages 173-180

Received 10 January 2020, Revised 3 March 2020, Accepted 16 March 2020, Available online 23 May 2020, Version of Record 28 January 2021.

E-mail: 1173315233@qq.com

Highlights

• The transformation from FGD gypsum to HH whiskers was investigated.

• An autocatalytic kinetic model was established to simulate transformation kinetics.

• Kinetic simulations and experimental data had a goodness of fit value of 0.990.

• The effects of hydrothermal conditions on transformation kinetics were examined.

Abstract

The controllable transformation of flue gas desulfurization (FGD) gypsum to calcium sulfate hemihydrate (HH) whiskers under facile, readily monitored, and cost-effective hydrothermal conditions could play a vital role in the preparation of high quality HH whiskers and improve our understanding of the transformation process. This work assessed the conversion of FGD gypsum to HH whiskers in 5×10^–4 mol/L H₂SO₄ and 1.5 wt% CuCl₂ at 120 °C while determining the effects of temperature as well as H₂SO₄ and CuCl₂ concentrations on transformation kinetics. The preparation of HH whiskers was found to involve a solution-mediated transformation from the dihydrate (DH) to the α-HH. This transition was determined to proceed via a dissolution crystallization mechanism, the rate of which was controlled by nucleation and growth of the HH whiskers. An autocatalytic kinetic model was established based on variations in the HH whiskers mole fraction over time, and this model accurately fit the experimental data with R² = 0.990. Increasing the temperature or H₂SO₄ concentration accelerated the transformation by modifying the super-saturation and water activity in the reaction solution, while increasing the CuCl₂ concentration had the opposite effect. The hydrothermal conditions had an important effect on the transformation from FGD gypsum to HH whiskers.

Graphical abstract

Keywords

FGD gypsum; Whisker; Hydrothermal condition; Transformation process; Kinetic

文章导读