Absorption of hydrogen sulfide in aqueous solutions of iodides containing dissolved iodine: enhancements in rates due to precipitated sulfur

Abstract

The specific rates of absorption of hydrogen sulfide in aqueous solutions of iodides, containing dissolved iodine, were measured in a 55 mm i.d. stirred cell, with batch and semi-batch modes of operation. The specific rates of absorption exceeded the rates that may be realised in the instantaneous reaction regime by factors as high as 8. This effect appears to be due to the precipitating (product) colloidal sulfur transporting dissolved hydrogen sulfide, through strong interaction, from near the gas-liquid interface into the bulk liquid. The relative values of the enhancement factor due to precipitated sulfur decrease with an increase in the concentration of dissolved iodine. A two-parameter model, incorporating the uptake of hydrogen sulfide by sulfur and the agglomeration of sulfur particles, has been developed which provides a reasonable framework to correlate the experimental data.