A conventional, speciated Pitzer ion-interaction model at 298 K and 0.1 MPa is presented for the NdCl₃ + H₂O system and mixtures containing HCl, NaCl, KCl, and CaCl₂. The model uses Nd³⁺, NdOH²⁺, Nd(OH)₂⁺, Nd(OH)₃⁰, NdCl²⁺, and NdCl₂⁺ solute species and was fitted to isopiestic, electromotive force (emf), and NdCl₃∙6H₂O solubility data. The model was then extended to pH values at which Nd(OH)₃, Nd(OH)₂Cl, and a speculative double salt, Nd(OH)₃∙NdCl₃, are stable. The two hydroxychloride salts enabled the model to join the stability fields of NdCl₃∙6H₂O and Nd(OH)₃ ensuring continuity in the range 2 < pH < 13. The activity coefficient model developed from the low pH [NdCl₃ + NaCl](aq) system reproduces the solubility of solid Nd(OH)₃(s) in water and NaCl(aq) with only the addition of standard state free energy terms for crystalline (cr) and amorphous (am) NdOH₃(s) and the Nd(OH)₂⁺ and Nd(OH)₃⁰ solute species. No Pitzer parameters involving NdOH²⁺, Nd(OH)₂⁺ and Nd(OH)₃⁰ were necessary to reproduce the full body of thermodynamic data over an ionic strength range from infinite dilution to the solubility limits of NaCl, KCl, CaCl₂∙6H₂O, Nd(OH)₃(s), the hydroxychloride salts, and for mixtures containing up to 4.5 molal HCl(aq). The model adds only five ‘binary’ and three ‘ternary’ Pitzer ion-interaction parameters to the H-Na-K-Ca-Cl-OH parameters in Harvie et al. (1984; hereafter HMW). The model is simpler, compositionally broader, and more accurate than previously published Pitzer ion-interaction models for aqueous neodymium-chloride and -hydroxide solutions containing HCl, NaCl, KCl or CaCl₂. The model has ramifications for geochemical modeling and uncertainty quantification of An(III) solubilities used to support certification of evaporite hosted nuclear waste repositories.

针对NdCl ₃ + H ₂ O系统以及含有HCl，NaCl，KCl和CaCl _2的混合物，给出了在298 K和0.1 MPa下的常规指定Pitzer离子相互作用模型。该模型使用的Nd ³⁺，NdOH ²⁺，钕（OH）₂ ⁺，钕（OH）₃ ⁰，氯化钕²⁺，和氯化钕_2个⁺溶质种类，并安装到等压，电动势（EMF），和氯化钕₃ ∙6H ₂ O溶解度数据。然后将模型扩展到pH值，在该值下Nd（OH）₃，Nd（OH）₂ Cl和投机性复盐Nd（OH）₃∙NdCl ₃稳定。两种羟基氯化物盐使模型能够加入NdCl ₃ ∙6H ₂ O和Nd（OH）₃的稳定性场，确保在2 <pH <13的范围内连续。活性系数模型是从低pH [NdCl ₃ + NaCl]建立的]（aq）系统仅添加晶体（cr）和无定形（am）NdOH ₃（s）的标准状态自由能项，即可重现固体Nd（OH）₃（s）在水和NaCl（aq）中的溶解度Nd（OH）₂ ⁺和Nd（OH）₃ ⁰溶质。涉及NdOH没有匹兹参数²⁺，钕（OH）₂ ⁺从无限稀释到NaCl，KCl，CaCl ₂ ∙6H ₂ O，Nd（OH）₃（s）的离子强度范围内，需要Nd（OH）₃ ⁰来重现整个热力学数据。羟基氯化物盐，以及含有不超过4.5摩尔HCl（aq）的混合物。该模型仅在Harvie等人的H-Na-K-Ca-Cl-OH参数中添加了五个“二元”和三个“三元” Pitzer离子相互作用参数。（1984年；以下简称HMW）。该模型比先前发布的含盐酸，氯化钠，氯化钾或氯化钙₂的氯化钕和氢氧化物水溶液的Pitzer离子相互作用模型更简单，组成更广泛且更准确。。该模型具有地球化学建模的分枝和用于支持蒸发岩托管核废料储存库认证的An（III）溶解度的不确定性量化。