Measurement of equilibrium nitrogen adsorption capacity of granular activated carbon including detail error analysis

Any adsorption based application needs information of equilibrium adsorption capacity of adsorbent (for any adsorptive). Measurement of equilibrium adsorption capacity and fitting the data into adsorption isotherm is not new in adsorption research, yet it is essential for every new adsorbent sample prepared. Accurate measurement in the cryogenic temperature domain needs special attention. Equilibrium nitrogen adsorption capacity of granular activated carbon prepared from coconut shell has been measured. Simple and cost effective volumetric method has been adopted for the measurement. Adsorption isotherms are measured from 300K to 175K with decrements of 25K. Experimental data are fitted into Langmuir equation. An exchange gas type cryostat has been used in the experiment to account the isotherms. Isosteric heat of adsorption has been calculated using Clausius-Clapeyron equation. The sources of error involving use of real gas equation and dead volume corrections particularly at low temperature and high pressure has been analyzed in details.