EVALUATION OF SURFACE-PROPERTIES OF EXHAUSTED CARBONS USED AS H2S ADSORBENTS IN SEWAGE-TREATMENT PLANTS

Physical and chemical properties of carbons previously used for air pu rification in sewage plants are investigated. The chosen samples are c haracterized by pH values (estimated according to ASTM D 3838) between 2 and 10. Their H2S breakthrough capacities are less than 0.01 g of H 2S/cm(3) of carbon. The surface chemistry and porous structure are det ermined using sorption of nitrogen. The influence of carbon pH and the type of deposited species on the capacity for physical adsorption are discussed. Compounds adsorbed/bound on the surface as a result of lon g term exposure to H2S are evaluated using potentiometric titration. T hermogravimetric analysis in inert and oxidizing atmospheres reveals t he dependence of ignition temperature on the surface chemistry of the sorbent (chemical compounds bound/deposited on the surface). (C) 1997 Elsevier Science Ltd.