In-situ desorption of hydrogen sulfide from activated carbon: effect of temperature, pH and flowrate

Hydrogen sulfide is an odorous gas anaerobically produced from decaying organic matter. It causes irritation when inhaled and is lethal at higher concentrations. Adsorption using activated carbon is one of the most effective methods for the removal of H₂S from gas streams. The desorption of H₂S from activated carbon can be facilitated using water. Due to their weak attachment affinity to H₂S, the desorption energy requirements are low. In this paper, activated carbon is used to adsorb H₂S from the air. The activated carbon is later regenerated using water. The effect of various parameters like temperature, pH and flowrate is studied. GC Sulfursorb Plus™ was used for this adsorption–desorption method. The H₂S stream passed through the activated carbon column, where the concentration was recorded at both the influent and effluent. Desorption was conducted with water at different temperatures (10 °C, 20 °C, 40 °C, 60 °C, 80 °C and 100 °C), flowrates (10 mL/min, 20 mL/min, 50 mL/min, 100 mL/min and 150 mL/min) and pH (5, 8, 10 and 12). The temperature was maintained using a hotplate and heat tape. Whereas pH was maintained using hydrochloric acid and sodium hydroxide, and flowrate using a peristaltic pump. Samples were collected and analyzed for sulfide concentration. Maximum sulfide concentration (560 µg/L) was noted at pH 5. However, the maximum cumulative mass (165 µg) was observed at 100 °C. Flowrate at which maximum removal (82.5 µg) was observed at 50 mL/min. GC Sulfursorb Plus™ has a high adsorption capacity, so desorption was partially effective.