Question

7. Adsorption of an organic solute on activated silica gel gave the following data after equilibrium. S (mg cm-3) 0.139 0.089 0.066 0.047 0.037 Ca (mg/g) 0.03 0.026 0.0225 0.021 0.018 Fit the data to an adsorption isotherm and calculate the constants.

Answer 1

Solution :

Here Adsorption of an organic solute on activated silica gel gave the following data after equilibrium :

S (mg cm-3) 0.139 0.089 0.066 0.047 0.037

Ca (mg/g) 0.03 0.026 0.0225 0.021 0.018

Here C = solute concentration in feed (S in mg/cm-3)

q = amounts of solute adsorbed on silica gel (Ca in mg/g)

now assume this adsorption follows freundlich isotherm,

frendlich isotherm equation is given as,

q = KC1/n

K and n are frendlich isotherm constants,

apply log on both side we will get,

ln(q) = ln(K) + ln(C) / n

now we draw a graph of ln(q) vs ln(C) and if it is linear then this adsorption follows freundlich isotherm.

so the graph of ln(q) vs ln(C) is linear so this adsorption follows freundlich isotherm.

So from the graph,we can find value of constants as follows:

1 / n = 0.372

n = 2.69

and ln(K) = -2.762

K = 0.0632 * 10-3 (mg cm-3)-0.372