The SIT model parameters for interactions of phosphate ions with Na+ and K+ ions accounting for dimerization of the H2PO4‐ anion

IF 3.1 3区 地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS
Andrey V. Plyasunov, Elena V. Cherkasova
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引用次数: 0

Abstract

The SIT model is a simple yet physically sound model for activity coefficients in aqueous solutions, which has only one binary interaction parameter for each pair of cations and anions. It has long been known that the SIT model performs poorly for the thermodynamic activity data for aqueous solutions of NaH2PO4 and KH2PO4. However, the previous treatment ignored the dimerization of the H2PO4 anion with the formation of H4P2O82, which has been convincingly demonstrated, mainly in Raman experiments. Here we show that explicitly taking into account the dimerization of the H2PO4 anion allows to reproduce accurately the experimental data on the stoichiometric mean ionic activity coefficients for aqueous NaH2PO4 and KH2PO4. The data were processed using relations from the thermodynamics of partially associated electrolytes. An additional source of information were the values of the dissociation constants of phosphoric acid in NaCl and KCl solutions. In total, we determined 8 SIT parameters for the interactions of Na+ and K+ with different phosphate ions at 298.15 K and 0.1 MPa.
磷酸盐离子与Na+和K+离子相互作用的SIT模型参数,说明H2PO4阴离子的二聚化
SIT模型是水溶液活度系数的一个简单而物理合理的模型,它对每一对阳离子和阴离子只有一个二元相互作用参数。人们早就知道,SIT模型对NaH2PO4和KH2PO4水溶液的热力学活度数据表现不佳。然而,先前的处理忽略了H2PO4‐阴离子形成H4P2O82‐的二聚化,这主要是在拉曼实验中得到了令人信服的证明。在这里,我们表明,明确考虑H2PO4阴离子的二聚化,可以准确地再现NaH2PO4和KH2PO4水溶液的化学计量平均离子活度系数的实验数据。利用部分缔合电解质的热力学关系对数据进行了处理。另一个信息来源是磷酸在NaCl和KCl溶液中的解离常数值。我们总共确定了Na+和K+与不同磷酸盐离子在298.15 K和0.1 MPa下相互作用的8个SIT参数。
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来源期刊
Applied Geochemistry
Applied Geochemistry 地学-地球化学与地球物理
CiteScore
6.10
自引率
8.80%
发文量
272
审稿时长
65 days
期刊介绍: Applied Geochemistry is an international journal devoted to publication of original research papers, rapid research communications and selected review papers in geochemistry and urban geochemistry which have some practical application to an aspect of human endeavour, such as the preservation of the environment, health, waste disposal and the search for resources. Papers on applications of inorganic, organic and isotope geochemistry and geochemical processes are therefore welcome provided they meet the main criterion. Spatial and temporal monitoring case studies are only of interest to our international readership if they present new ideas of broad application. Topics covered include: (1) Environmental geochemistry (including natural and anthropogenic aspects, and protection and remediation strategies); (2) Hydrogeochemistry (surface and groundwater); (3) Medical (urban) geochemistry; (4) The search for energy resources (in particular unconventional oil and gas or emerging metal resources); (5) Energy exploitation (in particular geothermal energy and CCS); (6) Upgrading of energy and mineral resources where there is a direct geochemical application; and (7) Waste disposal, including nuclear waste disposal.
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