The oxidation of ferrous ions in acidic sulfate solutions in the presence of cupric ions at elevated air pressures was investigated in a high-intensity gas-liquid contactor. The study was required for the design of the regeneration steps of the novel Vitrisol V R desulphurization process. The effects of the Fe 2þ concentration, Cu 2þ concentration, Fe 3þ concentration, initial H 2 SO 4 concentration, and partial oxygen pressure on the reaction rate were determined at three different temperatures, i.e., T ¼ 50 C, 70 C, and 90 C. Most of the experiments were determined to be affected by the mass transfer of oxygen, and therefore true intrinsic kinetics could not be fully determined. An increase in Fe 2þ and Cu 2þ concentrations, as well as the partial pressure of oxygen and temperature, increased the Fe 2þ oxidation rate. H 2 SO 4 did not influence the Fe 2þ oxidation rate. An increase in Fe 3þ concentration decreased the Fe 2þ oxidation rate. Although determined from experiments partially affected by mass transfer, a first order of reaction in Fe 2þ was observed, fractional orders in both Cu 2þ and O 2 were measured, a zero order in H 2 SO 4 was determined, and a negative, fractional order in Fe 3þ was obtained. The activation energy was estimated to be 31.3 kJ/mol. KEYWORDS Gas-liquid reaction; H 2 S removal; Fe(II) oxidation; influence of Cu(II); mass transfer; reaction behavior Fe 2 ðSO 4 Þ 3 þ CuSðsÞ ! 2FeSO 4 þ CuSO 4 þ S o ðsÞ: (2)

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