Estimation of Specific Surface Area using Langmuir Isotherm Method

A comparison of four widely used linear equations of the langmuir types of isotherm (the langmuir type 1, 2, 3 and 4 ) were examined in an experiment using dye sorption onto derived acid and salt treated fish activated carbon (h3po4-fac and zncl2-fac respectively). isotherm parameters obtained from the four langmuir linear equations differed. though langmuir type 1 is the most popular form, but the type 2 had the highest coefficient of determination (r2 = 0.931-0.984) compared with the other langmuir linear equations (with r2 values ranges of 0.696-0.982, 0.613-0.926 and 0.613-0.926 for langmuir type 1,3 and 4 isotherm models respectively). 3,7 bis(dimethylamino) phenothiazin-5-ium ion was used to measure the extent of monolayer coverage (qm) and specific surface areas (smb) following the application of type 1 isotherm. from this study, value obtained for the acid treated carbon (h3po4-fac with smb ; 18.170) is higher than that of the salt treated carbon, (zncl2-fac, smb ; 13.579) which compared more to that of commercial carbon, cac (smb ; 13.884) units in multiple of 10-3km2kg-1. the reliability of the langmuir type 1 and 2 methods seems very good in specific surface area estimation.