Adsorption of SO2 on sewage sludge-derived materials

Sewage sludge-derived materials carbonized at temperatures between 400 and 950 degreesC were used for adsorption of sulfur dioxide from dry and moist air. The materials were characterized using sorption of nitrogen and thermal analysis. The sulfur dioxide capacity was measured according to a laboratory-developed breakthrough test. It was found that the capacity of the adsorbents increases with increasing temperature of carbonization. It is likely that during carbonization at high temperatures such catalytic metals as calcium become active. They play a significant role in the SO2 removal process by neutralization of sulfuric acid formed as a result of oxidation of sulfur dioxide in wet conditions. Besides sulfuric acid, various sulfur-containing salts are formed. It was shown that, after their removal using water washing, the SO2 capacity significantly decreased.