Could help me please, what is the procedimeinto to calculate the pore size distribution by the BJH method, what is the equation and what corrections made are
BJH is an iterative method, which means you probably should use a computer procedure to do the calculations. You need the BJH expression and an adequate thickness curve (which one you use depends on the nature of the adsorbate and of your sample) [1,2]
You could also have a look at more modern methods, like NLDFT for example. Googling it will provide you with a bunch of good references.
The kelvin equation (base for BJH) takes into account the formation of a meniscus (which does not exist during the adsorption), this explains why it is "more correct" to use the desorption data. However in some cases the desorption data will only show information on pore entry and it is very common to observe a phantom peak around 4 nm. Therefore, it is interesting to observe BJH for adsorption and desorption.
I also have the same question as I worked with MIP as adsorbent so I have to compare the data for blank polymer and MIP. When I used the BJH desorption my pore size categorized as micropore whereas if used BET my pore classified as mesopore..