๐งฒ Adsorption Isotherms Calculator
Fit and evaluate Langmuir, Freundlich, and BET adsorption isotherms. Estimate adsorption capacity, saturation capacity, Langmuir constant, BET monolayer capacity, and specific surface area.
๐งซ Surface Adsorption Schematic
๐ Configuration
Key Equations:
Langmuir: q = qmaxKLC/(1+KLC)
Freundlich: q = KFC1/n
BET: q = qmCBETx/[(1โx)(1+(CBETโ1)x)]
Surface area: S = qmNAa
Langmuir: q = qmaxKLC/(1+KLC)
Freundlich: q = KFC1/n
BET: q = qmCBETx/[(1โx)(1+(CBETโ1)x)]
Surface area: S = qmNAa
๐ Results & Visualization
Configure inputs and click Calculate to view results.
๐ Calculation Methodology
Mathematical Model
Langmuir assumes monolayer adsorption on finite identical sites. Freundlich is empirical for heterogeneous surfaces. BET extends monolayer adsorption to multilayer adsorption and is commonly used for surface-area estimation.
Worked Example
For activated carbon with qmax = 250 mg/g, KL = 0.08 L/mg and C = 50 mg/L, the Langmuir equation estimates q and fractional surface coverage. For BET, qm and molecular area are converted to mยฒ/g.
Assumptions
- Equilibrium isothermal adsorption.
- Langmuir uses homogeneous monolayer sites.
- Freundlich does not enforce saturation at high concentration.
- BET surface area assumes known molecular cross-sectional area.