Example of adsorption data fitting.pdf

For the adsorption of n-hexane onto silica gel at 70 o C: (J. M. Smith, Chemical Engineering Kinetics, Chapter 7, Problem 7.6, 3rd edition, McGraw Hill (1987). T := ( 70 + 273.15) ⋅ K T = 343.15 K

 0.002   0.004    0.008   pC6H14 := ⋅ atm  0.0113   0.0156     0.0206 

R := 8.314⋅

 0.071   0.142    0.284  mol  X=  0.401  m3  0.554     0.732 

S := slope ( X , Y)

mol⋅ K

 10.5   16.0    27.2  − 5 mol  CA := ⋅ 10 ⋅  34.6  gm  43.0     47.3 

The concentration of hexane in the gas phase:

X := Cg

J

Y :=

CA = adsorbed concentration of n-hexane

Cg :=

p C6H14 R⋅ T

 0.676   0.888    1.045  kg  Y=  1.16  m3  1.288     1.547 

→  Cg 

C   A

I := intercept ( X , Y)

1.6

1.4

Y

1.2

1

0.8

0.6

0

0.2

0.4 X

0.6

0.8

Experimental points Line of best fit

The linearized form of the Langmuir adsorption isotherm: Cg CA

=

1 1 + Cg K cCm Cm

It implies that parameters are: Cm :=

Kc :=

1 S 1 I⋅ Cm

Cm = 0.831

mol

Kc = 1.815

m

kg 3

mol