This work focuses on a new aqueous biphasic system (ABS) composed of hydrophilic ionic liquids (1,3-dimethylimidazole phosphate dimethyl, [Mmim][DMP]), salts (K₃PO₄·3H₂O or K₂CO₃), and water. Liquid–liquid equilibrium (LLE) data for the ABS have been determined experimentally at T = 298.15 K. The binodal curves were fitted to the Merchuk, Pirdashti, and Jayapal equations. The order K₃PO₄·3H₂O > K₂CO₃ of recovery efficiency may be related to the Gibbs energy of hydration of the anions, the molar entropy of hydration of the anions, and the Hofmeister series for the strength of the kosmotropic salts, and the strength of [Mmim][DMP]–H₂O interactions and salt–H₂O interactions determined the phase ratio of the ABS. The effects of the anions structure on the phase equilibrium were investigated by Gaussian 09 software. It was found that the salting-out ability of different salts could be promoted by the increase of the anion valence of salt which can hydrate more water molecules, and the greater the binding energy of the salt with a single water molecule is, the easier it is for the salt to combine with water to form an ABS. To sum up, [Mmim][DMP] could be recovered from aqueous solution using a new ABS, and the recovery efficiency could reach 98.56%. This proposed method can be used as an effective way to recycle [Mmim][DMP] from aqueous solutions.

中文翻译：

---

[Mmim][DMP] + 盐水溶液双相系统的液-液平衡数据及其在 [Mmim][DMP] 回收中的应用

这项工作的重点是由亲水性离子液体（1,3-二甲基咪唑磷酸二甲酯，[Mmim][DMP]）、盐（K ₃ PO ₄ ·3H ₂ O 或 K ₂ CO ₃ ）组成的新型水性双相系统 (ABS ) ，和水。ABS 的液-液平衡 (LLE) 数据已在T = 298.15 K 时通过实验确定。双节点曲线适合 Merchuk、Pirdashti 和 Jayapal 方程。K ₃ PO ₄ ·3H ₂ O > K ₂ CO _3的顺序回收效率的高低可能与阴离子水合的吉布斯能、阴离子水合的摩尔熵、亲液盐强度的霍夫迈斯特级数和[Mmim][DMP]-H ₂的强度有关。 O 相互作用和盐-H ₂O 相互作用决定了 ABS 的相位比。采用Gaussian 09软件研究阴离子结构对相平衡的影响。研究发现，不同盐的盐析能力可以通过提高盐的阴离子化合价来促进，可以水合更多的水分子，盐与单个水分子的结合能越大，越容易水合。是盐与水结合形成ABS。综上所述，新型ABS可以从水溶液中回收[Mmim][DMP]，回收率可达98.56%。该方法可用作从水溶液中回收[Mmim][DMP]的有效方法。