Adsorption Properties of the Natural Carbon–Mineral Sorbent Shungite

Physicochemical methods were used for a comprehensive study of the structural/sorption properties of the natural mineral shungite. It was shown that the composite structure of the mineral determines its main physicochemical characteristics. The isosteric heat of adsorption of water vapour was estimated by calorimetric methods as 70 kJ/mol. This value corresponds to the interaction of water molecules with the vicinal hydroxy groups of the silica constituent of shungite; adsorption heats with values in the range 40–45 kJ/mol are characteristic of the carbon constituent of the sorbent. The heat of adsorption of benzene onto shungite was higher than that for hexane adsorption onto the mineral, indicating that specific interaction occurs between the benzene molecules and the active centres which exist on both the carbon and silica constituents of the mineral. It was shown that the adsorption parameters of shungite with respect to organic compounds which dissociate in an anionic manner suggest that the mineral could be applied as a filtering material with a sorptive action for water cleansing.