脱硫石膏转化α-半水石膏的特征及机理：实验与模拟

doi:10.16085/j.issn.1000-6613.2023-1118

摘要/Abstract

摘要：

脱硫石膏的高效利用可以有效缓解一系列环境问题，变废为宝。本文利用二水石膏在含有微量无水硫酸钠的乙二醇水溶液中制备α-半水石膏，探究温度（94~98℃）、乙二醇体积分数（25%~35%）、硫酸钠浓度（0.1~0.3mol/L）对二水石膏向α-半水石膏脱水转化过程的α-半水石膏摩尔分数和动力学参数变化。研究发现，在乙二醇水溶液中，二水石膏向α-半水石膏脱水转化过程符合分散动力学模型。随着温度和乙二醇浓度的增加，动力学参数α基本保持不变，而参数β显著增加，导致活化熵∆S*增大，进而导致能垒E_a降低，促进了二水石膏向α-半水石膏脱水转化。微量无水硫酸钠的添加，显著缩短了α-半水石膏的成核诱导时间。通过分子动力学模拟，增加硫酸钠的浓度，Na⁺与SO₄^2-的配位数增加，扩散系数绝对差值∆D降低，从而导致配位能力增加，解耦能力降低。本研究对高效利用脱硫石膏、掌握其向α-半水石膏的转化特征具有重要意义。

关键词: 二水石膏, α-半水石膏, 乙二醇, 结晶, 动力学模型, 分子模拟

Abstract:

The efficient utilization of desulfurized gypsum can effectively alleviate a series of environmental problems and turn waste into treasure. This paper used dihydrate gypsum to prepare α-hemihydrate gypsum in ethylene glycol aqueous solution containing trace anhydrous sodium sulfate, and explored the effects of temperature (94—98℃), ethylene glycol volume fraction (25%—35%), sodium sulfate concentration (0.1—0.3mol/L) on the mole fraction of α-hemihydrate gypsum and kinetic parameters in the dehydration conversion process from dihydrate gypsum to α-hemihydrate gypsum. The results showed that in ethylene glycol aqueous solution, the dehydration conversion process of dihydrate gypsum to α-hemihydrate gypsum conformed to the dispersion kinetic model. With the increase of temperature and ethylene glycol concentration, the kinetic parameter α remained basically unchanged, while the parameter β increased significantly, leading to an increase in the activation entropy (∆S*), which in turn led to a decrease in the energy barrier (E_a) and promoted the dehydration of dihydrate gypsum to α‍-hemihydrate gypsum. The addition of a small amount of anhydrous sodium sulfate significantly shortened the nucleation induction time of α-hemihydrate gypsum. Through molecular dynamics simulation, with increasing the concentration of sodium sulfate, the coordination number of Na⁺ and SO₄^2- increased, and the absolute difference of diffusion coefficient ∆D decreased, resulting in the increase of coordination ability and the decrease of decoupling ability. This study was of great significance for efficient utilization of desulfurized gypsum and mastering its conversion characteristics to α-hemihydrate gypsum.

Key words: dihydrate gypsum, α-hemihydrate gypsum, ethylene glycol, crystallization, kinetic model, molecular simulation

中图分类号:

TQ177.3⁺7

怀立业, 仲兆平, 杨宇轩. 脱硫石膏转化α-半水石膏的特征及机理：实验与模拟[J]. 化工进展, 2024, 43(8): 4694-4703.

HUAI Liye, ZHONG Zhaoping, YANG Yuxuan. Characteristics and mechanism of desulfurization gypsum to α-hemihydrate gypsum: Experiments and simulations[J]. Chemical Industry and Engineering Progress, 2024, 43(8): 4694-4703.

图/表 14

参考文献 26

1	JIANG Guangming, WANG Hao, CHEN Qiaoshan, et al. Preparation of alpha-calcium sulfate hemihydrate from FGD gypsum in chloride-free Ca(NO₃)₂ solution under mild conditions[J]. Fuel, 2016, 174: 235-241.
2	中华人民共和国生态环境部. 2020年全国大、中城市固体废物污染环境防治年报[EB/OL]. (2020-12-28) [2023-06-25]. .
	Ministry of Ecology and Environment of the People's Republic of China. Annual report on the prevention and control of environmental pollution by solid waste in large and medium cities in 2020 [EB/OL]. (2020-12-28) [2023-06-25]. .
3	王文飚, 许月阳, 薛建明, 等. 燃煤电厂脱硫技术研究进展及建议[J]. 电力科技与环保, 2020, 36(3): 1-5.
	WANG Wenbiao, XU Yueyang, XUE Jianming, et al. The research progress and suggestions of desulfurization technology in coal-fired power plants[J]. Electric Power Technology and Environmental Protection, 2020, 36(3): 1-5.
4	ZHU Zhencai, XU Lei, CHEN Guo'an. Effect of different whiskers on the physical and tribological properties of non-metallic friction materials[J]. Materials & Design, 2011, 32(1): 54-61.
5	ZHAO Wenpeng, GAO Chuanhui, SANG Hongfei, et al. Calcium sulfate hemihydrate whisker reinforced polyvinyl alcohol with improved shape memory effect[J]. RSC Advances, 2016, 6(58): 52982-52986.
6	JIANG Guangming, CHEN Qiaoshan, JIA Caiyun, et al. Controlled synthesis of monodisperse α-calcium sulfate hemihydrate nanoellipsoids with a porous structure[J]. Physical Chemistry Chemical Physics, 2015, 17(17): 11509-11515.
7	郝卓, 赵建华, 石秀芹, 等. 脱硫石膏液相法生产高强度α-石膏的工艺研究[J]. 电力科技与环保, 2011, 27(3): 33-34.
	HAO Zhuo, ZHAO Jianhua, SHI Xiuqin, et al. Research on parameters of liquid phase process in FGD gypsum utilization[J]. Electric Power Technology and Environmental Protection, 2011, 27(3): 33-34.
8	张小军, 许旭斌, 冯斌, 等. 630MW机组石膏高含水率原因分析及处理[J]. 电力科技与环保, 2022, 38(3): 238-244.
	ZHANG Xiaojun, XU Xubin, FENG Bin, et al. Analysis and treatment of high water content of gypsum in a 630MW unit[J]. Electric Power Technology and Environmental Protection, 2022, 38(3): 238-244.
9	LI Xianbo, ZHANG Qin, SHEN Zhihui, et al. L-aspartic acid: A crystal modifier for preparation of hemihydrate from phosphogypsum in CaCl₂ solution[J]. Journal of Crystal Growth, 2019, 511: 48-55.
10	GUAN Qingjun, SUN Wei, HU Yuehua, et al. A facile method of transforming FGD gypsum to α-CaSO₄·0.5H₂O whiskers with cetyltrimethylammonium bromide (CTAB) and KCl in glycerol-water solution[J]. Scientific Reports, 2017, 7: 7085.
11	GUAN Baohong, YANG Li, FU Hailu, et al. Alpha-calcium sulfate hemihydrate preparation from FGD gypsum in recycling mixed salt solutions[J]. Chemical Engineering Journal, 2011, 174(1): 296-303.
12	FU Hailuo, HUANG Jianshi, SHEN Luming, et al. Sodium cation-mediated crystallization of α-hemihydrate whiskers from gypsum in ethylene glycol-water solutions[J]. Crystal Growth & Design, 2018, 18(11): 6694-6701.
13	GUAN Baohong, YANG Liuchun, WU Zhongbiao, et al. Preparation of α-calcium sulfate hemihydrate from FGD gypsum in K, Mg-containing concentrated CaCl₂ solution under mild conditions[J]. Fuel, 2009, 88(7): 1286-1293.
14	LI Zhibao, DEMOPOULOS George P. Model-based construction of calcium sulfate phase-transition diagrams in the HCl-CaCl₂-H₂O system between 0 and 100℃[J]. Industrial & Engineering Chemistry Research, 2006, 45(13): 4517-4524.
15	FU Hailu, JIANG Guangming, WANG Hao, et al. Solution-mediated transformation kinetics of calcium sulfate dihydrate to α-calcium sulfate hemihydrate in CaCl₂ solutions at elevated temperature[J]. Industrial & Engineering Chemistry Research, 2013, 52(48): 17134-17139.
16	FELDMANN Thomas, DEMOPOULOS George P. Influence of impurities on crystallization kinetics of calcium sulfate dihydrate and hemihydrate in strong HCl-CaCl₂ solutions[J]. Industrial & Engineering Chemistry Research, 2013, 52(19): 6540-6549.
17	JIANG Guangming, FU Hailu, SAVINO Keith, et al. Nonlattice cation-SO₄ ^2– ion pairs in calcium sulfate hemihydrate nucleation[J]. Crystal Growth & Design, 2013, 13(11): 5128-5134.
18	WANG Bingqi, YANG Lin, CAO Jianxin. The influence of impurities on the dehydration and conversion process of calcium sulfate dihydrate to α-calcium sulfate hemihydrate in the two-step wet-process phosphoric acid production[J]. ACS Sustainable Chemistry & Engineering, 2021, 9(43): 14365-14374.
19	MAO Xiulong, SONG Xingfu, LU Guimin, et al. Control of crystal morphology and size of calcium sulfate whiskers in aqueous HCl solutions by additives: Experimental and molecular dynamics simulation studies[J]. Industrial and Engineering Chemistry Research, 2015, 54(17): 4781-4787.
20	孔令云, 全秀洁, 李朝波, 等. 乳化剂在集料化学成分表面吸附行为的分子模拟与试验论证[J]. 化工进展, 2020, 39(8): 3196-3204.
	KONG Lingyun, QUAN Xiujie, LI Chaobo, et al. Molecular simulation and experimental demonstration of adsorption behavior of emulsifier on surface of chemical composition of aggregate[J]. Chemical Industry and Engineering Progress, 2020, 39(8): 3196-3204.
21	GUAN Baohong, JIANG Guangming, FU Hailu, et al. Thermodynamic preparation window of alpha calcium sulfate hemihydrate from calcium sulfate dihydrate in non-electrolyte glycerol-water solution under mild conditions[J]. Industrial and Engineering Chemistry Research, 2011, 50(23): 13561-13567.
22	AVRAMI Melvin. Kinetics of phase change. I. General theory[J]. The Journal of Chemical Physics, 1939, 7(12): 1103-1112.
23	SKRDLA Peter J, ROBERTSON Rebecca T. Semiempirical equations for modeling solid-state kinetics based on a Maxwell-Boltzmann distribution of activation energies: Applications to a polymorphic transformation under crystallization slurry conditions and to the thermal decomposition of AgMnO₄ crystals[J]. The Journal of Physical Chemistry B, 2005, 109(21): 10611-10619.
24	JIANG Guangming, FU Wenyang, WANG Yuzheng, et al. Calcium sulfate hemihydrate nanowires: One robust material in separation of water from water-in-oil emulsion[J]. Environmental Science & Technology, 2017, 51(18): 10519-10525.
25	WANG Bingqi, YANG Lin, LUO Tong, et al. Study on the kinetics of hydration transformation from hemihydrate phosphogypsum to dihydrate phosphogypsum in simulated wet process phosphoric acid[J]. ACS Omega, 2021, 6(11): 7342-7350.
26	COLLINS Kim D. Ion hydration: Implications for cellular function, polyelectrolytes, and protein crystallization[J]. Biophysical Chemistry, 2006, 119(3): 271-281.

编辑推荐 0

Metrics

阅读次数

全文

HTML			PDF

最新录用	在线预览	正式出版	最新录用	在线预览	正式出版
0	0	1	0	0	71

来源	本网站	其他网站

次数	14	58
比例	19%	81%

摘要

111

最新录用	在线预览	正式出版

0	0	111

来源	本网站	其他网站

次数	20	91
比例	18%	82%

温度/℃	α/h	β/h^-2	R²	t_ind/h	v/h^-1	t_tot/h	K_sp,DH	K_sp,HH	a_w	S_HH
94	0.2821	0.1393	0.9995	2.01	0.23	5.93	1.61×10^-5	1.83×10^-5	0.853	1.10
95	0.2992	0.2021	0.9992	1.21	0.29	4.35	1.58×10^-5	1.76×10^-5	0.854	1.13
96	0.3177	0.2779	0.9978	0.63	0.39	2.94	1.55×10^-5	1.7×10^-5	0.855	1.15
97	0.2392	0.3783	0.9995	0.53	0.60	2.01	1.53×10^-5	1.63×10^-5	0.855	1.17
98	0.2572	0.6314	0.9998	0.41	0.75	1.61	1.50×10^-5	1.57×10^-5	0.856	1.20

温度/℃	α/h	β/h^-2	R²	t_ind/h	v/h^-1	t_tot/h	K_sp,DH	K_sp,HH	a_w	S_HH
94	0.2821	0.1393	0.9995	2.01	0.23	5.93	1.61×10^-5	1.83×10^-5	0.853	1.10
95	0.2992	0.2021	0.9992	1.21	0.29	4.35	1.58×10^-5	1.76×10^-5	0.854	1.13
96	0.3177	0.2779	0.9978	0.63	0.39	2.94	1.55×10^-5	1.7×10^-5	0.855	1.15
97	0.2392	0.3783	0.9995	0.53	0.60	2.01	1.53×10^-5	1.63×10^-5	0.855	1.17
98	0.2572	0.6314	0.9998	0.41	0.75	1.61	1.50×10^-5	1.57×10^-5	0.856	1.20

乙二醇体积分数/%	α/h	β/h^-2	R²	t_ind/h	v/h^-1	t_tot/h	K_sp,DH	K_sp,HH	a_w	S_HH
25.0	0.2522	0.1093	0.9997	2.59	0.21	6.85	1.55×10^-5	1.7×10^-5	0.872	1.09
27.5	0.2365	0.1810	0.9998	1.80	0.26	5.21	1.55×10^-5	1.7×10^-5	0.866	1.11
30.0	0.2992	0.2421	0.9992	1.21	0.29	4.35	1.55×10^-5	1.7×10^-5	0.854	1.13
32.5	0.2532	0.3234	0.9996	1.06	0.34	3.74	1.55×10^-5	1.7×10^-5	0.839	1.16
35.0	0.2965	0.5798	0.9993	0.77	0.44	2.78	1.55×10^-5	1.7×10^-5	0.823	1.19

乙二醇体积分数/%	α/h	β/h^-2	R²	t_ind/h	v/h^-1	t_tot/h	K_sp,DH	K_sp,HH	a_w	S_HH
25.0	0.2522	0.1093	0.9997	2.59	0.21	6.85	1.55×10^-5	1.7×10^-5	0.872	1.09
27.5	0.2365	0.1810	0.9998	1.80	0.26	5.21	1.55×10^-5	1.7×10^-5	0.866	1.11
30.0	0.2992	0.2421	0.9992	1.21	0.29	4.35	1.55×10^-5	1.7×10^-5	0.854	1.13
32.5	0.2532	0.3234	0.9996	1.06	0.34	3.74	1.55×10^-5	1.7×10^-5	0.839	1.16
35.0	0.2965	0.5798	0.9993	0.77	0.44	2.78	1.55×10^-5	1.7×10^-5	0.823	1.19

Na₂SO₄浓度/mol·L^-1	α/h	β/h^-2	R²	t_ind/h	v/h^-1	t_tot/h	K_sp,DH	K_sp,HH	a_w	S_HH
0.10	0.3364	0.0644	0.9994	3.19	0.16	8.76	1.55×10^-5	1.7×10^-5	0.889	1.06
0.15	0.3132	0.1031	0.9976	2.40	0.20	6.87	1.55×10^-5	1.7×10^-5	0.871	1.09
0.20	0.2992	0.2421	0.9992	1.21	0.29	4.35	1.55×10^-5	1.7×10^-5	0.854	1.13
0.25	0.2760	0.6871	0.9988	0.39	0.47	2.29	1.55×10^-5	1.7×10^-5	0.834	1.22
0.30	0.2967	2.0467	0.9995	0.17	0.83	1.26	1.55×10^-5	1.7×10^-5	0.751	1.37