same initial state as the experiments, that is, all the beds saturated with the desorbent
at a given initial pressure [113].
The SMB process performance was evaluated according to Equations 40 until
47, where Q represents the flow rates in standard liters per minute (SLPM) and P and
T are the standard pressure and temperature. R is the ideal gas constant and M
i is the
molar mass in kgÁmol
À1 . y
i is the average molar fraction of species i during one step,
y i is the molar fraction of species i, and V s is the adsorbent volume in m
3 . The
subscripts X, R, F, and D correspond to extract, raffinate, feed, and desorbent,
respectively. A and B superscripts correspond to the less retained species and the
more retained species, respectively.
Desorbent Free Raffinate Purity (%)
Pu R ¼
y
A
R
y
A
R þ y
B
R
 100
ð40Þ
Desorbent Free Extract Purity (%)
Pu X ¼
y
B
X
y
A
X þ y
B
X
 100
ð41Þ
Raffinate Recovery (%)
Rec R ¼
y
A
R Q R
y A
F Q F
 100
ð42Þ
Extract Recovery (%)
Re c X ¼
y
B
X Q X
y B
F Q F
 100
ð43Þ
180
V. F. D. Martins et al.