Removal of NO2 from gas stream by activated bio-carbons from physical activation of residue of supercritical extraction of hops

Abstract Production of activated bio-carbons from the residue of supercritical extraction of hops has been described. The precursor was first subjected to pyrolysis at 500 and 700 °C in nitrogen atmosphere. The bio-chars were next subjected to physical activation at 700 and 800 °C in carbon dioxide atmosphere. The effects of pyrolysis and activation temperature on the physicochemical properties and sorption capacity toward NO2 were established. The results have shown that by physical activation of residue of supercritical extraction of hops it is possible to produce bio-sorbents with very high capacity towards NO2, reaching maximum 79.2 mg/g. It has been proved that the effectiveness of NO2 removal to large extent depends on the conditions of adsorption. The presence of steam in the stream of gases and preliminary wetting of the adsorbent bed have positive effect on the adsorption of NO2 by the bio-sorbents obtained.