Structural, thermal and energetic characteristics of synthetic active carbons prepared on the basis of ion-exchange resin Amberlite IRC 84

Abstract

A series of activated carbons was prepared from the ion-exchange resin (Amberlite IRC-84, Rohm and Haas) differing in Ca2+ content and studied by means of adsorption (N2 adsorption) and thermogravimetric methods. Thermogravimetry was performed in two ways: classical and quasi-isothermal. Preparation processes proceeded in different conditions (temperature and atmosphere). This resulted in changes of their porosity and thermal stability. As shown by the studies, low temperature and calcium ion content are not suitable for obtaining carbon materials with desirable structural properties and good thermal resistance. Ca2+ ions increase makes it possible to obtain carbonaceous materials with a large specific surface area, well-developed porosity and high thermal stability. The quasi-isothermal thermogravimetric analysis allowed to characterize energetic and structural heterogeneity of active carbons. Changes in the free energies of adsorbed water layer during their desorption as well as dependence of the effective radius of a drop evaporated from the surface on the adsorbed water concentration were determined. The dependence {text{d}}G/{text{d}}M_{{{text{H}}_{2} {text{O}}}} left( {{text{C}}_{{{text{H}}_{2} {text{O}}}} } right) was examined under the conditions of low coverage of carbon surfaces with the adsorbed water which may indicate formation of various types of water clusters on the surfaces.