Analysis of the relationship between H2S removal capacity and surface properties of unimpregnated activated carbons

The H2S breakthrough capacity was measured on two series of activated carbo ns of a coconut shell and a bituminous coal origins. To broaden the spectru m of surface features the samples were oxidized using nitric acid or ammoni um persulfate under conditions chosen to preserve their pore structures. Th en the carbons were characterized using Boehm titration, potentiometric tit ration, thermal analysis, temperature programmed desorption, sorption of ni trogen, and sorption of water. It was found that the choice of unimpregnate d carbon for application as H2S adsorbent should be made based on parameter s of its acidity such as number of acidic groups, pH of surface, amount of surface groups oxygen, or weight loss associated to decomposition of surfac e oxygen species. The results obtained from the analyses of six unimpregnat ed carbon samples suggest that there are certain threshold values of these quantities which, when exceeded, have a dramatic effect on the H2S breakthr ough capacity.