The role of sulfur in palladium transport and fractionation from platinum by hydrothermal fluids

IF 4.5 1区 地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS Geochimica et Cosmochimica Acta Pub Date : 2024-12-17 DOI:10.1016/j.gca.2024.12.019
C. Laskar, E.F. Bazarkina, G.S. Pokrovski
{"title":"The role of sulfur in palladium transport and fractionation from platinum by hydrothermal fluids","authors":"C. Laskar, E.F. Bazarkina, G.S. Pokrovski","doi":"10.1016/j.gca.2024.12.019","DOIUrl":null,"url":null,"abstract":"The solubility of palladium sulfide (PdS<ce:inf loc=\"post\">(s)</ce:inf>) has been measured in H<ce:inf loc=\"post\">2</ce:inf>S/HS<ce:sup loc=\"post\">–</ce:sup> aqueous solutions across wide ranges of sulfur concentrations (0.5–1.2 molal) and pH (5–8) at temperatures from 50 to 300 °C and pressures from 90 to 600 bar, using a hydrothermal flexible-cell reactor allowing controlled fluid injection and sampling. Combined with thermodynamic modeling and analysis of available literature data, our results demonstrate that palladium tetrahydrosulfide, Pd<ce:sup loc=\"post\">II</ce:sup>(HS)<ce:inf loc=\"post\">4</ce:inf><ce:sup loc=\"post\">2–</ce:sup>, is the dominant complex in sulfide-rich moderate-temperature hydrothermal fluids. The equilibrium constants of PdS<ce:inf loc=\"post\">(s)</ce:inf> dissolution reaction, PdS<ce:inf loc=\"post\">(s)</ce:inf> + 3 H<ce:inf loc=\"post\">2</ce:inf>S<ce:sup loc=\"post\">0</ce:sup><ce:inf loc=\"post\">(aq)</ce:inf> = Pd(HS)<ce:inf loc=\"post\">4</ce:inf><ce:sup loc=\"post\">2–</ce:sup> + 2H<ce:sup loc=\"post\">+</ce:sup> (K<ce:inf loc=\"post\">s4,Pd</ce:inf>), generated in this study can be described by the function log<ce:inf loc=\"post\">10</ce:inf>K<ce:inf loc=\"post\">s4,Pd</ce:inf> = (196.4 ± 60.0) – (11384 ± 3567)/<ce:italic>T</ce:italic>(K) – (71.24 ± 19.52) × log<ce:inf loc=\"post\">10</ce:inf><ce:italic>T</ce:italic>(K), valid over the temperature range 25–300 °C and from saturated vapor pressure to 600 bar. Our results, combined with recent analogous PtS<ce:inf loc=\"post\">(s)</ce:inf> solubility data, enabled the derivation of a self-consistent set of thermodynamic properties of Pd(HS)<ce:inf loc=\"post\">4</ce:inf><ce:sup loc=\"post\">2–</ce:sup> and Pt(HS)<ce:inf loc=\"post\">4</ce:inf><ce:sup loc=\"post\">2–</ce:sup> in the framework of the HKF model. Solubility predictions of PdS<ce:inf loc=\"post\">(s)</ce:inf> using these properties yield maximum solubility values of 1 ppb Pd, as the tetrahydrosulfide complex, in H<ce:inf loc=\"post\">2</ce:inf>S-bearing hydrothermal fluids (&gt;0.01 m S) at moderate temperatures (50–350 °C) and near-neutral pH (6–7), whereas chloride complexes are predominant at acidic pH (&lt;4). The Pd/Pt atomic ratio in typical H<ce:inf loc=\"post\">2</ce:inf>S-bearing hydrothermal fluids at 300 °C in equilibrium with PdS<ce:inf loc=\"post\">(s)</ce:inf> and PtS<ce:inf loc=\"post\">(s)</ce:inf> varies from &gt; 10<ce:sup loc=\"post\">4</ce:sup> at pH &lt; 2 to 10<ce:sup loc=\"post\">–2</ce:sup> at pH &gt; 3, corresponding to the change from chloride- to sulfide-dominated speciation for both metals. However, the absolute solubilities of both chloride and sulfide complexes are too small over the whole pH range to significantly contribute to Pd vs. Pt fractionations observed in hydrothermal environments. Among different factors that may lead to such fractionations, the role of polysulfide sulfur species, including trisulfur radical ions, should be considered in future studies.","PeriodicalId":327,"journal":{"name":"Geochimica et Cosmochimica Acta","volume":"28 1","pages":""},"PeriodicalIF":4.5000,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Geochimica et Cosmochimica Acta","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1016/j.gca.2024.12.019","RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}
引用次数: 0

Abstract

The solubility of palladium sulfide (PdS(s)) has been measured in H2S/HS aqueous solutions across wide ranges of sulfur concentrations (0.5–1.2 molal) and pH (5–8) at temperatures from 50 to 300 °C and pressures from 90 to 600 bar, using a hydrothermal flexible-cell reactor allowing controlled fluid injection and sampling. Combined with thermodynamic modeling and analysis of available literature data, our results demonstrate that palladium tetrahydrosulfide, PdII(HS)42–, is the dominant complex in sulfide-rich moderate-temperature hydrothermal fluids. The equilibrium constants of PdS(s) dissolution reaction, PdS(s) + 3 H2S0(aq) = Pd(HS)42– + 2H+ (Ks4,Pd), generated in this study can be described by the function log10Ks4,Pd = (196.4 ± 60.0) – (11384 ± 3567)/T(K) – (71.24 ± 19.52) × log10T(K), valid over the temperature range 25–300 °C and from saturated vapor pressure to 600 bar. Our results, combined with recent analogous PtS(s) solubility data, enabled the derivation of a self-consistent set of thermodynamic properties of Pd(HS)42– and Pt(HS)42– in the framework of the HKF model. Solubility predictions of PdS(s) using these properties yield maximum solubility values of 1 ppb Pd, as the tetrahydrosulfide complex, in H2S-bearing hydrothermal fluids (>0.01 m S) at moderate temperatures (50–350 °C) and near-neutral pH (6–7), whereas chloride complexes are predominant at acidic pH (<4). The Pd/Pt atomic ratio in typical H2S-bearing hydrothermal fluids at 300 °C in equilibrium with PdS(s) and PtS(s) varies from > 104 at pH < 2 to 10–2 at pH > 3, corresponding to the change from chloride- to sulfide-dominated speciation for both metals. However, the absolute solubilities of both chloride and sulfide complexes are too small over the whole pH range to significantly contribute to Pd vs. Pt fractionations observed in hydrothermal environments. Among different factors that may lead to such fractionations, the role of polysulfide sulfur species, including trisulfur radical ions, should be considered in future studies.
查看原文
分享 分享
微信好友 朋友圈 QQ好友 复制链接
本刊更多论文
求助全文
约1分钟内获得全文 去求助
来源期刊
Geochimica et Cosmochimica Acta
Geochimica et Cosmochimica Acta 地学-地球化学与地球物理
CiteScore
9.60
自引率
14.00%
发文量
437
审稿时长
6 months
期刊介绍: Geochimica et Cosmochimica Acta publishes research papers in a wide range of subjects in terrestrial geochemistry, meteoritics, and planetary geochemistry. The scope of the journal includes: 1). Physical chemistry of gases, aqueous solutions, glasses, and crystalline solids 2). Igneous and metamorphic petrology 3). Chemical processes in the atmosphere, hydrosphere, biosphere, and lithosphere of the Earth 4). Organic geochemistry 5). Isotope geochemistry 6). Meteoritics and meteorite impacts 7). Lunar science; and 8). Planetary geochemistry.
期刊最新文献
Methane Index and TEX86 values in cold seep sediments: Implications for paleo-environmental reconstructions Gamma-irradiation-induced reduction of aqueous Se(VI) by natural pyrite Two isotopically distinct populations of refractory inclusions in the EHa3 chondrite Sahara 97072 – Significance for understanding the evolution of the CAI-formation region Competitive and cooperative effects of chloride on palladium(II) adsorption to iron (oxyhydr)oxides: Implications for mobility during weathering Oxygen isotope constraints on proto-kimberlite melt modification through assimilation of low δ18O recycled crust in the deep lithosphere
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
现在去查看 取消
×
提示
确定
0
微信
客服QQ
Book学术公众号 扫码关注我们
反馈
×
意见反馈
请填写您的意见或建议
请填写您的手机或邮箱
已复制链接
已复制链接
快去分享给好友吧!
我知道了
×
扫码分享
扫码分享
Book学术官方微信
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术
文献互助 智能选刊 最新文献 互助须知 联系我们:info@booksci.cn
Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。
Copyright © 2023 Book学术 All rights reserved.
ghs 京公网安备 11010802042870号 京ICP备2023020795号-1