Kinetics of the reactive absorption of hydrogen sulfide into aqueous ferric sulfate solutions

The reactive absorption of H2S into aqueous Fe-2(SO4)(3) solutions, was studied in a stirred cell reactor operated batchwise with and without a flat interface. The temperature was varied from 25degreesC to 65degreesC and the concentrations of aqueous Fe-2(SO4)(3) solutions ranged from 0.025 to 0.8 kmol/m(3). The corresponding initial pH values ranged from 2 to 0.8, respectively. Additional measurements were conducted at other pH values by addition of NaOH. The H2S partial pressure was varied between 0 and 200 mbar. The rate of H2S absorption was measured by recording the pressure drop as a function of time during batch absorption experiments. In this system the absorbed H2S reacts with ferric iron and is oxidized to elemental sulfur. The kinetic results are in agreement with enhanced absorption due to a fast chemical reaction according to the film theory. The reaction of ferric sulfate and H2S appears to proceed irreversibly and is first order in both the total concentrations of ferric iron and H2S. The activation energy for the reaction was calculated to be 22 kJ/mol. (C) 2002 Elsevier Science Ltd. AU rights reserved.