Kinetics of SO2 absorption into fairly concentrated sulphuric acid solutions containing hydrogen peroxide

Absorption of SO2, diluted with nitrogen up to partial pressures of 500 Pa, was performed at 20 °C and 1 atm with water and sulphuric acid solutions containing hydrogen peroxide in a cable contactor. The absorption rate was determined for various SO2 partial pressures and different concentrations of sulphuric acid (within the range 0–40 wt.%) and hydrogen peroxide in the scrubbing liquid. It was found that the SO2 absorption rate increases with the hydrogen peroxide concentration and decreases as the acidity of the scrubbing liquid increases. Experimental results were interpreted according to the two-film theory of absorption with chemical reaction, considering fast irreversible reaction of SO2 with H2O2. This led to the determination of an overall kinetic parameter, depending on the sulphuric acid concentration, which can be used to design absorption towers. A kinetic constant, which decreases strongly with the rise of cH2SO4, was deduced thanks to the estimation of diffusivities and Henryʹs coefficients of SO2 for sulphuric solutions.