Abstract
Commercial granular charcoal was evacuated at 105, 300 and 800 degrees C. The effect of evacuation on pH of charcoal solution was studied. The pH showed considerable increase with evacuation. The infrared (IR) spectra of the charcoal samples before and after evacuation at these temperatures was also recorded and interpreted for the presence of both acidic and basic groups, found in the charcoal matrix. Acidic group showed considerable decrease with increase in evacuation from 105 to 800 degrees C while no effect was found for basic group. The adsorption studies of two dyes, methyl orange (acidic) and methylene blue (basic) were conducted at all the three evacuated granular charcoal samples at 25 degrees C as function of stirring time, concentration and evacuation. Adsorption equilibrium was established at four hours in case of both the dyes irrespective of their nature, concentration and evacuation temperature. Evacuation showed a positive effect on the adsorption of dyes at equilibrium time, however, highest adsorption was found at 800 degrees C. The adsorption data was also applied to Freundlich and Langmuir isotherms.