Nitrogen-enriched activated carbons prepared by the activation of coniferous tree sawdust and their application in the removal of Nitrogen dioxide

Abstract

A technology of obtaining nitrogen-enriched activated carbons from coniferous tree sawdust by direct activation of the precursor and physical activation with CO2 is described. The effect of activation time, pyrolysis temperature as well as modification with urea on the textural parameters, acid–base character of the surface and sorption properties of activated carbons has been tested. The resulting carbons were characterised by low-temperature nitrogen sorption and determination of the number of surface oxygen groups. The sorption properties of the materials obtained were characterised by nitrogen dioxide adsorption in dry and wet conditions. The final products were nitrogen-enriched microporous activated carbons of medium-developed surface, showing very diverse nitrogen content and acidic–basic character of the surface. The results obtained in our study have proved that through suitable choice of the activation and modification procedure of coniferous tree sawdust, activated carbons can be produced with high capacity towards nitrogen dioxide adsorption, reaching to 69 and 46 mg NO2/g in dry and wet conditions, respectively. The results of our study have also shown that the adsorption ability of carbonaceous adsorbents depends both on the method of preparation as well as on the textural parameters and acid–base properties of the adsorbents surface.