Question

iii. What are the differences between Freundlinch and Langmuir isotherms, explain which one is better? Use data in Table 1 to conclude your arguments. Use: Langmuir Isotherm SK[C] [CS]= 1+K,[C] Freundlich Isotherm [CS] = K[C]" Table 1. Concentration of the solute in the stationary phase Solute concentration q(mg/g) 2x10- 8x10-2 1x10- 5x10- 7x10- 1.00 c (mg/ml) 3.2x10-9 3.28x10-6 1x10 3.12 x102 1.68x10" 1.0

Answer 1

Chemical Engireesing (1) Difference between Freundlinch and longmuir isotherms. 6 (a) Langmuir Isotherm The molewles are adsorbed at discrete active sites on the surface. Each active site adsorb one mokule only. The adsorbing sunface is energetically uniform There is no interaction among the adsorbed molecules. It considess as a monolayer Phenomena. [e-do keq [E (6) Freundlinch Isotherm It keq [c It consider possiblity of multilayer adsorption. It has assumed that the heat of adsorption is not some for all the sites, it means they are not en Uniform. energetically Each site can adsorb moleculle. more than one It assumes that the amant adsorbed at equilibrium has a power low dependence on the partial pressure (or concentredion) of the solente. qe = ker [Ca]'n