In the literature [20] there are already some urea solubility data
in electrolyte solutions at 298.15 K. However, since most of the
results in the present work were obtained at physiological temperature
(i.e. 310.15 K), the urea solubility was also measured at
310.15 K in 3 and 5 molal NaCl solutions in the present work.
Fig. 4 represents the effect of temperature and salt addition on
the solubility of urea in aqueous solutions. As this figure shows,
the solubility of urea increases as the temperature increases. Also,
a salting-in effect can be observed, which is obviously independent
of the temperature. ePC-SAFT predicts this behavior without introducing
any new adjustable parameter. It should be mentioned that
the procedure and the related parameters for solid–liquid equilibrium
calculation were published in previous works and for the sake
of brevity do not repeated in this work [27].