Removal of H2S gas by in situ generation of ferrate (VI) in aqueous alkaline solution

This study demonstrated a new approach of odorous gas treatment in a wet scrubbing-oxidation system with in situ generation of ferrate(VI), in which gaseous H2S could be quickly absorbed by aqueous alkaline solution and rapidly oxidized by liquid ferrate(VI) generated through electrochemical synthesis in situ. Ferrate(VI) ion production in alkaline solution (NaOH) was studied and the results showed optimum temperature for producing ferrate(VI) ion in 14 molar electrolyte solution was 50°C, and increasing voltage in rang of 1 to 10 V leading to more ion production. From ferrate(VI) self-decomposition test, it was found that 80% of ferrate ion was decomposed in 100 minutes and the increase in the temperature from 23°C to 80°C result in self-decomposing of 57% of ferrate ion. In the second part of tests, in situ generated ferrate(VI) has been used to H2S removal. The effect of temperature, ferrate ion solution concentration and gas containing H2S flow rate on H2S removal efficiency was investigated and these results were found: the optimum temperature for H2S removal was 50 °C in the test conditions, at increasing of ferrate ion concentration from 0.6 to 1.65  , 98% of H2S was removed from the gas, as well as at increasing the solution by 1 , 95% of H2S was removed.