Enhancements in the absorption rate of acetylene into aqueous solutions of iron chelates of HEDTA, caused by the presence of fine, freshly precipitated sulfur particles, have been investigated in a stirred cell reactor with flat interface. The acetylene gas is essentially inert towards the iron chelate, whose presence is required solely for in situ precipitation of sulfur from hydrogen sulfide, i.e. for introducing sulfur into the system prior to acetylene absorption. The sulfur particle size distributions were determined using Coulter Counter measurements. The rate data were interpreted by developing, and using, a heterogeneous, unsteady state mass transfer model based on Danckwerts' surface renewal theory and particle-to-interface adhesion. The enhancement factor is shown to depend upon the fraction of the interface 'covered' by the solid particles, the average particle size, the distribution coefficient of the solute partitioning between the solid and the liquid phases and the physical gas-liquid (liquid side) mass transfer coefficient. The model predicts the trends in the enhancements correctly, and has been shown to interpret the experimental data reasonably well.
As a reference case, the absorption of acetylene into slurries of fine carbon particles in similar liquid media was also studied. The sulfur and carbon particles indeed behave similarly and the additional data on carbon particle systems also points to the qualitative validity of the proposed model. Nevertheless, the new model seems to be too simple for predicting quantitative agreement.