In situ optical and Raman spectroscopic observations of the effects of pressure and fluid composition on liquid-liquid phase separation in aqueous cadmium sulfate solutions (<= 400 degrees C, 50 MPa) with geological and geochemical implications

doi:10.1016/j.gca.2017.05.020

CORC > 深海科学与工程研究所 > 中国科学院深海科学与工程研究所 > 深海科学研究部 > 深海极端环境模拟研究实验室

	In situ optical and Raman spectroscopic observations of the effects of pressure and fluid composition on liquid-liquid phase separation in aqueous cadmium sulfate solutions (<= 400 degrees C, 50 MPa) with geological and geochemical implications
	Wang, Xiaoyu 2; Wan, Ye 2; Wang, Xiaolin 1,2; Hu, Wenxuan 1,2; Chou, I-Ming3 ; Chen, Ying3 ; Xu, Zhimin 2; Wang, Xiaolin(Nanjing Univ, Sch Earth Sci & Engn, State Key Lab Mineral Deposits Res, Nanjing 210023, Jiangsu, Peoples R China)
刊名	GEOCHIMICA ET COSMOCHIMICA ACTA
	2017-08-15
卷号	211 页码:133-152
DOI	10.1016/j.gca.2017.05.020
产权排序	第1完成单位 ; 第2完成单位 ; 第3完成单位
文献子类	Article
英文摘要	This study presents the first description of liquid-liquid phase separation in a vapor-saturated CdSO4 solution at temperatures above 222.2 degrees C in fused silica capillary tubing, in which a sulfate-rich liquid (Srich) phase separates from an initially homogeneous aqueous solution and coexists with the remaining sulfate-poor liquid (Spoor) phase and a vapor phase. This phase behavior is characterized by a lower critical solution temperature (similar to 222.2 degrees C), which is a macroscale property of polymer mixtures. In situ Raman spectroscopy shows an increase in Cd2+-SO42- associations with increasing temperature, especially in the immiscible Srich phase. Phase behavior observations and in situ Raman spectroscopic analyses confirm our previous conclusion that strong ion associations are responsible for the liquid-liquid phase separation in inorganic solutions. The effects of pressure and the fluid composition on liquid-liquid phase separation are also investigated. The temperature of liquid-liquid phase separation increases almost linearly with pressure at a rate of similar to 0.5 degrees C/MPa and decreases with the addition of methanol. Both decreases in pressure and increases in the methanol concentration decrease the dielectric constant of the solutions, favoring the Cd2+-SO42- interaction and thus liquid-liquid phase separation. The capillary size also exerts a strong influence on liquid-liquid phase separation because the immiscible Srich phase is more stable in fused silica capillary tubing with an inner diameter of <= 300 mu m. Therefore, liquid-liquid phase separation can occur in hydrothermal fluids hosted in porous rocks/sediments, especially those that are rich in low-dielectric-constant components and/or at low pressures. Liquid-liquid phase separation may play an important role in the formation of Mississippi-valley-type ore deposits because the ore-forming fluids are enriched in low-dielectric-constant components. The occurrence of liquid-liquid phase separation can promote the enrichment of Zn and S in fluids and accelerate thermochemical sulfate reduction as well as the mineralization of sphalerite. In addition, liquid-liquid phase separation may contribute to the enrichment and transport of metals in other hydrothermal systems because it significantly increases the capability of fluids to carry certain components. Finally, we observe crystallization within the S-rich droplet, confirming that large clusters and separated dense liquids can act as pre-cursors for crystallization. Therefore, crystallization through liquid-liquid phase separation can represent an important mechanism of nucleation and crystal growth in hydrothermal fluids. (C) 2017 Elsevier Ltd. All rights reserved.
URL标识	查看原文
WOS关键词	AMORPHOUS CALCIUM-CARBONATE ; VALLEY-TYPE DEPOSITS ; HYDROTHERMAL ORE-DEPOSITS ; PORE-SIZE DISTRIBUTION ; ZINC-LEAD DISTRICT ; DIELECTRIC-CONSTANT ; HIGH-TEMPERATURES ; HYGROSCOPIC PROPERTIES ; URANYL SULFATE ; SUPERCRITICAL FLUIDS
语种	英语
WOS记录号	WOS:000405786800009
内容类型	期刊论文
源URL	[http://ir.idsse.ac.cn/handle/183446/3958]
专题	深海科学研究部_深海极端环境模拟研究实验室
通讯作者	Wang, Xiaolin; Wang, Xiaolin(Nanjing Univ, Sch Earth Sci & Engn, State Key Lab Mineral Deposits Res, Nanjing 210023, Jiangsu, Peoples R China)
作者单位	1.Nanjing Univ, Inst Energy Sci, Nanjing 210023, Jiangsu, Peoples R China 2.Nanjing Univ, Sch Earth Sci & Engn, State Key Lab Mineral Deposits Res, Nanjing 210023, Jiangsu, Peoples R China 3.Chinese Acad Sci, Inst Deep Sea Sci & Engn, Lab Expt Study Deep Sea Extreme Condit, Sanya 572000, Hainan, Peoples R China
推荐引用方式 GB/T 7714	Wang, Xiaoyu,Wan, Ye,Wang, Xiaolin,et al. In situ optical and Raman spectroscopic observations of the effects of pressure and fluid composition on liquid-liquid phase separation in aqueous cadmium sulfate solutions (<= 400 degrees C, 50 MPa) with geological and geochemical implications[J]. GEOCHIMICA ET COSMOCHIMICA ACTA,2017,211:133-152.
APA	Wang, Xiaoyu.,Wan, Ye.,Wang, Xiaolin.,Hu, Wenxuan.,Chou, I-Ming.,...&Wang, Xiaolin.(2017).In situ optical and Raman spectroscopic observations of the effects of pressure and fluid composition on liquid-liquid phase separation in aqueous cadmium sulfate solutions (<= 400 degrees C, 50 MPa) with geological and geochemical implications.GEOCHIMICA ET COSMOCHIMICA ACTA,211,133-152.
MLA	Wang, Xiaoyu,et al."In situ optical and Raman spectroscopic observations of the effects of pressure and fluid composition on liquid-liquid phase separation in aqueous cadmium sulfate solutions (<= 400 degrees C, 50 MPa) with geological and geochemical implications".GEOCHIMICA ET COSMOCHIMICA ACTA 211(2017):133-152.