Determination of specific surface of activated mesocarbons by sorption of organic vapors

Abstract

The determination of specific surface of activated mesocarbons prepared from coal tar pitch by sorption of organic vapors and the operating factors affecting their performances were investigated. Proposed paper deals with alternative experimental method based on weight registration during adsorption of pure vapors of volatile organic compounds VOCs on tested samples. Thermogravimeter TGA-HP50 was used for sorption experiments where activated mesocarbon microbeads were the sorbent and vapors of benzene, toluene, acetone and cyclohexane were used as adsorbate. Primary data were actual weight of the tested sorbent and absolute pressure of organic vapor. Experimental data were fitted by Langmuir model of adsorption isotherm. Specific surface was determined from evaluated parameters. Obtained results were compared with results from standard nitrogen S-BET method. Specific surfaces evaluated from both methods are comparable. The influence of important parameters such as chemical activation, extraction and addition of catalytic agents on activated mesocarbons was studied too. Coal tar pitch as raw material was thermally treated together with Lewis acid (FeCl3). Final solid sorbents were prepared by chemical activation of pyridine-insoluble (PI) matters using potassium hydroxide. Weight ratio of activated agent (potassium hydroxide) to PI matters was 1:5, and temperature of activation was 850 °C. It was found that three samples which were activated had greater specific surface area than the one (B) that was not activated, also as they are appropriate for adsorbing the selected adsorptives.