The effect of mineral matter on the physicochemical and sorption properties of brown coal-based activated carbons

A series of new carbonaceous adsorbents has been obtained by means of direct and physical activation of Polish brown coal, characterised by high mineral matter content. The influence of activation procedure on the porous structure development, acidic and basic surface groups generation as well as the sorptive properties of the adsorbents prepared toward liquid and gas pollutants was tested. Additionally the effect of mineral matter presence on the physicochemical and sorption properties of materials prepared was studied. The final products were micro/mesoporous activated carbons of medium developed surface area ranging from 407 to 674 m2/g, showing strongly basic or intermediate acidic-basic character of the surface. The results obtained during this study showed that direct and physical activation of low quality brown coal led to activated carbons with very good sorption capacity both toward gas contamination of acidic character (especially nitrogen dioxide) as well as toward methylene blue and inorganic pollutants of molecules of size similar to that of iodine molecules. It was also proved that demineralization of prepared activated carbons by hydrochloric acid significantly reduced their ability to toxic gases sorption, but simultaneously increased the efficiency of removing impurities from the liquid phase.