nonlinear_bet: Non-linear BET Model

In AdsorpR: Adsorption Isotherm Models

Non-linear BET Model

Description

The non-linear BET isotherm extends the Langmuir model to multilayer adsorption and is used to evaluate surface area and porosity of adsorbents. It fits the model directly using non-linear least squares estimation.

The BET equation is expressed as:

Q = \frac{Q_m \cdot C_b \cdot C_e}{(C_s - C_e) \left(1 + (C_b - 1) \cdot \frac{C_e}{C_s} \right)}

where Q is the amount adsorbed, C_e is the equilibrium concentration, C_s is the saturation concentration, Q_m is the monolayer adsorption capacity, and C_b is the BET constant.

The model uses non-linear regression to estimate parameters.

Usage

nonlinear_bet(Ce, Qe, Cs = max(Ce) * 1.1)

Arguments

Ce	Numeric vector of equilibrium concentrations.
Qe	Numeric vector of amount adsorbed.
Cs	Saturation concentration (default is 110% of the maximum equilibrium concentration).

Value

A named list of BET parameters and model details, including estimated parameters, model statistics, and a diagnostic plot.

See Also

Other nonlinear models: nonlinear_freundlich(), nonlinear_langmuir(), nonlinear_temkin()

Examples

Ce <- c(1, 2.5, 4, 5.5, 7)
Qe <- c(0.4, 1.0, 1.7, 2.3, 2.7)
result <- nonlinear_bet(Ce, Qe)
print(result$`BET Qm (mg/g)`)
print(result$`BET Cb`)
print(result$AIC)
print(result$`Pseudo R2`)
print(result$Plot)

AdsorpR documentation built on April 12, 2025, 1:23 a.m.