Kinetics of absorption of oxygen into aqueous solutions of sodium sulphide containing finely powdered activated carbon in a slurry reactor

The oxidation of sodium sulphide solutions containing finely powdered activated carbon by gaseous oxygen was investigated in order to clarify the role of catalyst particles which were considerably smaller than the liquid-film thickness. Experiments were conducted in a stirred cell with an unbroken interface, at a temperature range of 288–308 K, and at atmospheric pressures. The system was found to have a complex nature, exhibiting first an initial induction, then a constant reaction rate and finally a catalyst poisoning periods. Only the constant gas absorption rate period, was analysed quantitatively and depending on the conditions, an enhancement factor of up to 12 was observed, which was, however, unaffected by the catalyst loadings exceeding a certain value. The reaction was found to be half order in oxygen and first order in sulphide ion, and had an activation energy of 23.2 kcal/mol.