What are types of adsorption isotherms?

1. Langmuir isotherm
2. Freundlich isotherm
3. BET isotherm
4. Temkin isotherm
5. Dubinin-Radushkevich isotherm
6. Flory-Huggins isotherm
7. Redlich-Peterson isotherm
8. Sips isotherm
9. Toth isotherm
10. Jovanovic isotherm

Langmuir Isotherm:

- Assumes a monolayer of adsorbate on the adsorbent surface.
- Adsorption occurs on specific, uniform sites.
- No interaction between adsorbed molecules.
- Describes saturation behavior at high adsorbate concentrations.

Freundlich Isotherm:

- Empirically derived equation that describes a heterogeneous surface.
- Adsorption occurs on multiple sites with varying affinities.
- Adsorbate molecules interact and form multilayers.

BET Isotherm (Brunauer-Emmett-Teller):

- Assumes a multilayer formation on a heterogeneous surface.
- Adsorption occurs in layers, with each layer having a constant adsorption energy.
- Describes both monolayer and multilayer adsorption.

Type I Isotherm:

- Applies to microporous solids.
- Shows a sharp rise in adsorption at low adsorbate concentrations, followed by saturation.
- Indicates monolayer formation within the micropores.

Type II Isotherm:

- Describes non-porous or mesoporous solids.
- Exhibits a gradual increase in adsorption and a plateau at high adsorbate concentrations.
- Suggests the formation of multilayers on the surface.

Type III Isotherm:

- Indicates weak interactions between the adsorbate and adsorbent.
- Adsorption increases steadily without reaching a plateau.

Type IV Isotherm:

- Exhibits a hysteresis loop during adsorption and desorption.
- Indicates capillary condensation in mesoporous solids.

Type V Isotherm:

- Similar to Type I, but with a weaker initial rise in adsorption.
- Suggests adsorption on a heterogeneous surface with both strong and weak sites.