H2S adsorption/oxidation on unmodified activated carbons: importance of prehumidification

Three microporous activated carbons supplied by Norit(R) (of peat and bituminous coal origin) were used in this study as hydrogen sulfide adsorbents. Their surface properties were evaluated by means of nitrogen adsorption, Boehm titration, potentiometric titration, and thermal analysis. The results show that the carbons significantly differ in their pore structure and surface chemistry. This is reflected in their hydrogen sulfide breakthrough capacity. The breakthrough capacity is underestimated when not enough water is adsorbed on the carbon surface. The performance follows the expectations after extensive humidification of the sorbents' surfaces. Moderately low pH in the acidic range of coal-based carbon, Vapure 612, promotes the oxidation of H2S to sulfur oxides which is important from the point of view of water regeneration. The high pH of peat-based carbon, RB 4, results in H2S oxidation to elemental sulfur. (C) 2001 Elsevier Science Ltd. All rights reserved.