ADSORPTION

1
ADSORPTION
2
Surface Activity of Solutes
Solute, c
?
?
?o
Solute, c
Solutes that decrease surface tension are called
surfactants
3
Here is me. I am trying to get your attention
now.
4
Adsorption
More solute we have more surface tension (free
energy) is - unfavorable Solute is repelled
by surface
More solute we have less surface tension (free
energy) is - favorable As a result solute
concentrates onto surface - adsorption
5
Specific Adsorption
Surface area, ?
? - thickness of adsorption layer
Volume of adsorption layer, ?.?
Solute concentration, c
Surface concentration, c ?
Specific adsorption, ?
6
Adsorption Isotherms
?
Langmuir isotherm
?max
(for a solution)
c or p
(for a gas)
7
More Adsorption Isotherms
(a) Langmuir
(b) Multilayer formation
?
?
first layer
c or P
c or P
(c) Positive cooperativity
(d) Hysteresis
?
?
c or P
c or P