How can i fit for BET adsorption isotherm for liquid phase on origin? I tried Langmuir , freudlich and temkin model but none fit, adjusted R2 was less than 0.9
The BET isotherm possesses 3 adjustable parameters, so, you need to use a try-and-error method. For this, guess the parameter Cs and fit the model to obtain R2 (call it R1^2). Then guess another Cs and fit the model and obtain R2^2. If R2^2>R1^2, it means the second guess is better than the first one. So, guess the third value for Cs close to the second guess. Continue guessing the Cs until you reach to a maximum achievable R2.