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.