We have developed a new apparatus for the measurement of adsorption isotherms on the basis of desorption method between two equilibrium states, and the enthalpy of adsorption at constant adsorbate, pressure and temperature conditions. The adsorption isotherms of methane on highly porous activated carbon (Maxsorb-III) over a temperature ranging from 278 to 333K and pressures varying from 0.1 to 2.0 MPa have been measured experimentally by the newly developed apparatus. The experimentally measured isotherm data are fitted in Dubinin-Astakhov (DA), Langmuir and Tóth isotherm models, extrapolated up to 5 MPa and agreed well within the acceptable uncertainty limits. The results are also compared with the studies of similar specimens previously conducted by other researchers using different adsorption measurement methods and found to be fairly consistent.
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