Chapter 26, Problem 26.2P

(a)

Interpretation Introduction

Interpretation:

The membrane selectivity for the given separation process is to be determined.

Concept Introduction:

For a membrane separation of binary mixture, the membrane selectivity $\left(\alpha \right)$ is defined as:

  $\alpha =\frac{Q_A}{Q_B}$ .......…… (1)

Here, $Q_A$ and $Q_B$ are the permeabilities of species A and B through the membrane respectively.

(b)

Interpretation Introduction

Interpretation:

The permeate composition obtained is to be calculated if vacuum is used on the downstream side.

Concept Introduction:

For a binary mixture being separated in a membrane separator, when $R=0$ , the equation used to calculate the mole fraction of species A in permeate $\left({x^{\prime }}_{P\left(A\right)}\right)$ is:

  ${y^{\prime }}_A=\frac{x_{F\left(A\right)}\alpha }{1+x_{F\left(A\right)}\left(\alpha -1\right)}$ ...........…… (2)

Here, $x_{F\left(A\right)}$ is the mole fraction of A in feed, $\alpha$ is the membrane selectivity, and $R$ is the ratio of permeate pressure to the feed pressure.