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Cadmium Behavior in Sulfur-bearing Aqueous Environments: Insight from CdS Solubility Measurements at 25–80°Cстатья
Информация о цитировании статьи получена из
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 1 мая 2024 г.
- Авторы: Bazarkina E.F., Zotov A.V., Chareev D.A., Truche L., Tarnopolskaya M.E.
- Журнал: Geology of Ore Deposits
- Том: 65
- Номер: 1
- Год издания: 2023
- Издательство: Maik Nauka/Interperiodica Publishing
- Местоположение издательства: Russian Federation
- Первая страница: 28
- Последняя страница: 43
- DOI: 10.1134/s1075701523010038
- Аннотация: The present experimental study explores the effects of temperature and sulfur in Cd aqueous geochemistry under reduced conditions. Greenockite CdS solubility is measured in H2O–H2S–HClO4–NaHS solutions at 25–80°C as a function of pH and sulfur concentration. Based on solubility product measurements in highly acid solutions, the standard thermodynamic properties of greenockite (CdS) are revised, and the recommended value of ΔfG0298.15 for greenockite CdS(s) is –151.5 ± 0.3 kJ mol–1. The stability of greenockite (CdS) is higher than predicted by calculations using previous literature data. At 80°C, the stability constants for Cd–HS complexes are measured for the first time, the values are 10–5.65 ± 1.00 for CdS(s) + H+ = CdHS+, 10–6.00 ± 0.40 for CdS(s) + H2S0(aq) = Cd(HS)02(aq), 10–3.87 ± 0.10 for CdS(s) + H2S0(aq) + HS– = Cd(HS)−3, and 10–3.53 ± 0.20 for CdS(s) + H2S0(aq) + 2HS– = Cd(HS)2−4. Modeling of Cd behavior at 3–200°C shows that Cd–HS species are more important than previously believed. The fraction of Cd(HS)2−nn (n = 1–4) complexes increases with m H2S and decreases with T. Thus, in euxinic marine environments with m H2S ≥ 10–5, Cd speciation changes from Cd–Cl to Cd-HS. This speciation change is expected to affect Cd isotope fractionation and should be accounted for when applying Cd isotopic signature as a paleo tracer in marine sediments. The new thermodynamic data are indispensable for modeling Cd behavior in response to pH, T, and m H2S. As a function of these parameters, sulfur has the main control on Cd geochemistry being the main factor of Cd precipitation at low m H2S and favoring Cd mobilization at high m H2S.
- Добавил в систему: Чареев Дмитрий Александрович