Langmuir Adsorption

Langmuir (1916): adsorption equilibrium θ = KP/(1+KP) where K=kₐ/k_d. Assumes monolayer, identical sites, no lateral interactions. The kinetics: dθ/dt = kₐP(1−θ) − k_d·θ. This model underlies heterogeneous catalysis, gas sensors, and drug-receptor binding. The isotherm (right) shows equilibrium coverage vs pressure with your current K value.