Dipartimento di Fisica, Università Roma Tre , Via della Vasca Navale 84, I-00146 Roma, Italy.
J Phys Chem B. 2011 Dec 8;115(48):14161-6. doi: 10.1021/jp2045977. Epub 2011 Aug 18.
In this paper we investigate by means of molecular dynamics computer simulations how the hypothesized liquid-liquid critical point of water shifts in supercooled aqueous solutions of salt as a function of concentration. We study sodium chloride solutions in TIP4P water, NaCl(aq), for concentrations c = 1.36 mol/kg and c = 2.10 mol/kg. The liquid-liquid critical point is found up to the highest concentration investigated, and its position in the P-T plane shifts to higher temperatures and lower pressures upon increasing concentration. For c = 2.10 mol/kg it is also located very close to the temperature of maximum density line of the system. The results are discussed and compared with previous results for bulk TIP4P water and for c = 0.67 mol/kg NaCl(aq) and with experimental findings. We observe a progressive shrinkage of the low-density liquid region when the concentration of salt increases; this suggests an eventual disappearance of the liquid-liquid coexistence upon further increase of NaCl concentration.
本文通过分子动力学计算机模拟研究了盐在过冷水溶液中的假设的液-液相变点如何随浓度而变化。我们研究了 TIP4P 水中的氯化钠溶液，NaCl(aq)，浓度为 c = 1.36 mol/kg 和 c = 2.10 mol/kg。在研究的最高浓度下发现了液-液相变点，并且随着浓度的增加，它在 P-T 平面上的位置向更高的温度和更低的压力移动。对于 c = 2.10 mol/kg，它也非常接近系统的最大密度线的温度。结果与以前关于 TIP4P 水的整体和 c = 0.67 mol/kg NaCl(aq)的结果以及实验结果进行了讨论和比较。当盐浓度增加时，我们观察到低密度液体区域逐渐收缩；这表明随着 NaCl 浓度的进一步增加，液-液共存可能最终消失。
