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Langmuir Isotherm Calculator.

Calculate equilibrium loading with the Langmuir adsorption equation.

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Equilibrium loading: 5 units

Equilibrium loading

5.000000units
Saturation fraction: 0.5

Saturation fraction

0.5000

Educational arithmetic only. Keep units consistent and use measured or explicitly supplied chemistry inputs; this tool does not infer reaction pathways, property tables, or safety guidance.

Use Cases

Adsorption capacity estimation

Determine how much adsorbate will be adsorbed at a given concentration, useful for designing adsorption processes.

Example: Estimate loading of a pollutant on activated carbon at 10 mg/L.

Isotherm fitting

Compare experimental data with Langmuir predictions to check if adsorption follows monolayer behavior.

Example: Fit data for protein binding to a resin.

Frequently Asked Questions

What is the Langmuir isotherm equation used for?
The Langmuir isotherm models monolayer adsorption on a homogeneous surface. It calculates the equilibrium loading (amount adsorbed) as a function of concentration, given the maximum loading and affinity constant.
How do I interpret the affinity constant?
The affinity constant (often denoted K) indicates the strength of adsorption. A higher value means stronger binding, so the loading approaches maximum at lower concentrations.
What units should I use for concentration?
Use any consistent concentration unit (e.g., mol/L, mg/L). The affinity constant must be in reciprocal concentration units (e.g., L/mol) to match. The loading will be in the same units as maximum loading.

Tips & Common Mistakes

Tips

  • Ensure the affinity constant and concentration units are reciprocal (e.g., L/mol and mol/L) to get correct loading.
  • The Langmuir model assumes a homogeneous surface and monolayer adsorption; use it only if your system meets these assumptions.
  • For a quick check, at very high concentration, loading should approach the maximum loading value.
  • If you have multiple data points, you can use this calculator to predict loading at each concentration and compare with experiments.

Common Mistakes to Avoid

  • Using concentration and affinity constant with inconsistent units, leading to incorrect results.
  • Assuming the Langmuir isotherm applies to multilayer adsorption or heterogeneous surfaces.
  • Entering the maximum loading as a total amount instead of per unit mass or area, which can cause misinterpretation.

Last updated: August 13, 2026