Effect of surface characteristics of wood-based activated carbons on adsorption of hydrogen sulfide

Three wood-based commercial activated carbons supplied by Westvaco were stu died as adsorbents of hydrogen sulfide. The initial materials were characte rized using sorption of nitrogen, Boehm titration, potentiometric titration , water sorption, thermal analysis, and temperature-programmed desorption. The breakthrough tests were done at low concentrations of H2S in the input gas to simulate conditions in water pollution control plants where carbon b eds are used as odor adsorbents. In spite of apparent general similarities in the origin of the materials, method of activation, surface chemistry, an d porosity, significant differences in their performance as hydrogen sulfid e adsorbents were observed. Results show that the combined effect of the pr esence of pores large enough to accommodate surface functional groups and s mall enough to have the film of water at relatively low pressure contribute s to oxidation of hydrogen sulfide. Moreover, there are features of activat ed carbon surfaces such as local environment of acidic/basic groups along w ith the presence of alkali metals which are important to the oxidation proc ess, (C) 1999 Academic Press.