Technical Bulletin No. 0023: Absorption of Odorous Sulfur Compounds in Chlorine and Caustic Solutions (AQTB)

The attached National Council Technical Bulletin #23 is a summary of research on the absorption and oxidation of hydrogen sulfide and methyl mercaptan in off-gas streams. This investigation was conducted by George L. Jensen, under the direction of Prof. Donald Adams, at the National Council's Washington State University air pollution research project. These gases were selected for study because they are representative of odorous sulfur compounds present in kraft pulping off-gases. It was concluded from these studies, that acidic and basic hypochlorite solutions are not effective in deodorizing methyl mercaptan since the only reaction product formed is odorous dimethyl disulfide. Hydrogen sulfide, however, was converted to elemental sulfur by hypochlorite solutions having a pH of 12 or greater. Caustic solutions act as effective absorbents for both gases when the hydroxide to sulfide feed ratio is maintained greater than 1.8. It can be concluded from these investigations that elimination of aliphatic sulfur compounds from off-gas stream represent more of a problem than does the removal of hydrogen sulfide.