From the intercept and slop of the linear plot you may find the constants.

The isotherm is as follows:

q=A*Ce/(1+B*Ce^a)

Due to the implicit form of the equation, you need to use a software like MATLAB to do trial and error to fined the constants.

The other tool could be Excel software. Put the experimental data in the excel worksheet. Then guess a value for "A" (e.g. A=1), then plot ln(A*Ce/q-1) vs ln(Ce). Use "Add trend line" to fit a linear equation on the data points. Write down the R^2 value. Then change the "A" (increase or decrease) and see whether the R^2 tends to unity or not. Please note that "A" may vary between 0.01 to several hundreds.

See the attached as well:

Thank you Mr. Ali for your answer, I found your explanation very useful. 

am using linear form of Redlich- Peterson Isotherm. There is a constant term A that need to be find in the equation. What are the possible ways of finding the constant term?

How to find the constant term in the linear form of Redlich-Peterson isotherm? -

you can try using Scidavis software, its free and easy to use,u can look at the tutorial in youtube;

https://www.youtube.com/watch?v=jouoShwM2ew

hope it helps =)

@ Azduwin Khasri

How to install Scidavis/ I have downloaded from source forge, but there is no installation set up, can you tell me in detail?

Thanks

Ravi Kumar D.V.

you can download the program from the following link ( if you still have the problem)

https://sourceforge.net/projects/scidavis/

Thank you Dr. Ali. Your explanation is simple and clear.