Example 08.03 SLE of Benzene - Ethanol Using UNIQUAC

problem:

Calculate the solubility of benzene(2) in ethanol(1) at 260 K. The activity coefficients in the liquid phase should be taken into account by the UNIQUAC equation.

general

constants

and

definitions:

input data

Solution

First calculate the activity (x*g) of solid benzene at T = 260K:

Now we need a function to calculate the activity coefficients as f(x,T) using UNIQUAC:

We use the root function to find the mole fraction of component 2 for which the liquid activity is equal to the solid activity in the mole fraction range from 0 to 1. As a starting value we set the mole fraction to the solid activity.

For a graphical representation, this calculations can be defined as function of temperature.

starting value for root