Evaluation of surface properties of exhausted carbons used as H2S adsorbents in sewage treatment plants Original Research Article

Physical and chemical properties of carbons previously used for air purification in sewage plants are investigated. The chosen samples are characterized by pH values (estimated according to ASTM D 3838) between 2 and 10. Their H2S breakthrough capacities are less than 0.01 g of H2S/cm3 of carbon. The surface chemistry and porous structure are determined 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 long term exposure to H2S are evaluated using potentiometric titration. Thermogravimetric analysis in inert and oxidizing atmospheres reveals the dependence of ignition temperature on the surface chemistry of the sorbent (chemical compounds bound/deposited on the surface).