School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China; Key Laboratory of Hunan Province for Clean and Efficient Utilisation of Strategic Calcium-containing Mineral Resources, Central South University, Changsha 410083, China.
School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China; Key Laboratory of Hunan Province for Clean and Efficient Utilisation of Strategic Calcium-containing Mineral Resources, Central South University, Changsha 410083, China.
Sci Total Environ. 2019 Feb 1;649:344-352. doi: 10.1016/j.scitotenv.2018.08.416. Epub 2018 Aug 30.
This study introduces the use of a waste by-product from wet limestone flue gas desulfurization as a potential material for fluoride removal. Systematic laboratory-scale experiments were tested to identify the fluoride removal performance and determine the underlying mechanism. Flue gas desulfurization (FGD) gypsum removes 93.31% of fluoride from 109 mg/L to 7.3 mg/L. Fluoride can be efficiently removed at the optimum pH range of 5-11. Kinetics analysis indicates that the theoretical fluoride capacity at 1 g/L FGD gypsum is 96.9 mg/g. Equilibrium speciation analysis indicates that the decrease of system pH to lower than 5 is unsuitable for the formation of calcium fluoride, and the increase of system pH to higher than 11 opposes calcium release from FGD gypsum. Thermodynamic analysis confirms the feasibility of converting calcium sulphate into calcium fluoride at pH > 5. FGD gypsum and precipitates were characterized to describe their surface morphology, elemental composition and crystalline phase. Results indicate that FGD gypsum removes fluoride through the combination of calcium with fluoride to generate calcium fluoride.
本研究介绍了一种将湿式石灰石烟气脱硫的副产物用作潜在氟化物去除材料的方法。通过系统的实验室规模实验测试，确定了氟化物去除性能并阐明了其作用机制。烟气脱硫石膏可将 109mg/L 的氟化物去除至 7.3mg/L，去除率达 93.31%。氟化物可在最佳 pH 值范围 5-11 内有效去除。动力学分析表明，在 1g/L 烟气脱硫石膏时的理论氟化物容量为 96.9mg/g。平衡形态分析表明，体系 pH 值降低至 5 以下不利于氟化钙的形成，而 pH 值升高至 11 以上则不利于 FGD 石膏中钙的释放。热力学分析证实了在 pH 值>5 的条件下将硫酸钙转化为氟化钙的可行性。通过对 FGD 石膏和沉淀物进行特性描述，阐明了它们的表面形态、元素组成和晶体相。结果表明，FGD 石膏通过钙与氟的结合去除氟，生成氟化钙。
