Keywords: Kinetics; autoxidation; sulphur(IV); Ag(I); catalysis; inhibition; organic compounds

Abstract

The kinetics of atmospheric autoxidation of sulphur(IV) by silver(I) in the pH range 4.02−5.25 was studied. The aqueous phase autoxidation of sulphur(IV) was the major factor responsible for acidification of atmospheric aqueous system. The role of organics which act as inhibitors of silver(I) catalysed autoxidation of sulphur(IV) in the acidic medium was identified and based on the observed results following rate law and a free radical mechanism was proposed: d[S(lV)]/dt = (k1+ k2[Ag(I)]) [S(lV)]/1 + B [organics].