Kinetics and Mechanisms of Carbonation Conversion of Aqueous Sodium Sulfide to Hydrogen Sulfide

Abstract

<p> The objectives of the present study were to investigate the reaction mechanisms and the effects of certain physical variables on the overall reaction rate of the conversion of aqueous Na2S to gaseous H2S by bubbling with CO2 gas, which is a simultaneous absorption-desorption reaction.</p> <p> The dependence of reaction rate on the physical variables investigated were the volumetric flow rate and the CO2 partial pressure of inlet gas and reaction temperature. Potential advantages of a pressurized reaction system were also studied. It was found that the effect of reaction temperature on the overall reaction rate was relatively small as compared to that of inlet gas flow rate and CO2 partial pressure.</p> <p> Gas-liquid interfacial area was estimated and the overall reaction rate constant determined. It was found that the carbonation conversion of Na2S is first order with respect to both the HS- ion concentration of the liquid phase and the CO2 partial pressure of the inlet gas.</p> <p> The rate limiting step of the overall conversion reaction, under the present laboratory conditions, appeared to be the desorption of hydrogen sulfide.</p>