Look the Links.

http://www.sciencedirect.com/science/article/pii/S1876619613000405

www.azonano.com/article.aspx?ArticleID=1480

www.labqmc.quantachrome.com/vapor_sorption.html

www.sciencemag.org/cgi/content/full/322/5898/80

www.cdc.gov/niosh/pdfs/86-102-c.pdf

You can see the following link

http://pubs.acs.org/doi/abs/10.1021/jp207332n 

To see equations and calculations can visit the site here:

 http://en.wikipedia.org/wiki/Freundlich_equation 

http://en.wikipedia.org/wiki/Langmuir_equation 

To see the Langmuir isotherm can visit the site here:

http://www.tutorvista.com/content/chemistry/chemistry-iv/surface-chemistry/langmuir-isotherm.php

And to see Freundlich isotherm, please refer to the following website:

http://www.tutorvista.com/content/chemistry/chemistry-iv/surface-chemistry/freundlich-adsorption-isotherm.php