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.

在简便，易于监控且经济高效的水热条件下，烟气脱硫（FGD）石膏可控转化为硫酸半水钙（HH）晶须可在制备高质量HH晶须方面发挥至关重要的作用，并增进我们对转型过程。这项工作评估了FGD石膏在120°C下在5×10 ^–4 mol / LH ₂ SO ₄和1.5 wt％CuCl ₂中转化为HH晶须的过程，同时确定了温度以及H ₂ SO ₄和CuCl _{2的影响。}浓度对转化动力学的影响。发现HH晶须的制备涉及从二水合物（DH）到α-HH的溶液介导的转化。确定该转变是通过溶解结晶机理进行的，该机理由HH晶须的形核和生长控制。基于HH晶须摩尔分数随时间的变化建立了自动催化动力学模型，该模型准确拟合了实验数据，R ² = 0.990。通过改变反应溶液中的过饱和度和水活度，增加温度或H ₂ SO ₄浓度可加速转化，同时增加CuCl ₂集中产生相反的效果。水热条件对从烟气脱硫石膏向HH晶须的转变有重要影响。