The autooxidation of hydrogen sulfide in the presence of hematite

The kinetics of the catalyzed autoxidation of hydrogen sulfide to sulfate and thiosulfate has been investigated in the pH range 5.0–7.0. The concentration of H2S was varied between 1.35 and 2.02×10−3 M, and that of O2 between 3.4 10−5 and 1.35 10−4 M. The catalytic effect of the α-Fe2O3 has been observed. Experimental data suggest that the catalyzed reaction proceeds via the formation of two different inner sphere surface complexes FeIIIS− and FeIIISH. Four oxidized surface complexes FeIIISO2−,FeIIIS2O−FeIIISO4−, and FeIIIS2O3− has been postulated to explain the formation of sulfate and thiosulfate that are released into the solution without a further electron transfer to the surface. Fit parameters for the equations describing the distribution of the oxidation products are obtained.