The Chemical Behavior of Low Valence Sulfur Compounds. VII. The Oxidation of Ammonium Sulfide and Ammonium Sulfite with Compressed Oxygen in Aqueous Ammonia Solution

Abstract The oxidation of ammonium sulfide and ammonium sulfite with compressed oxygen in aqueous ammonia soultion was studied in order to confirm the formation of ammonium sulfamate. Ammonium sulfite is easily oxidized to ammonium thiosulfate through polysulfides with oxygen and further to ammonium sulfamate and ammonium sulfate. Suitable conditions for producing ammonium sulfamate were found to be: initial concentration of ammonium sulfide 2.0 mol/l, temperature 100°C, concentration of ammonia 12 mol/l, concentration of cupric ion 0.1 mol/l and oxygen pressure 50 kg/cm2. Though ammonium sulfite is wholly oxidized to ammonium sulfate under the same conditions, it is partially oxidized to ammonium sulfamate besides sulfate in the presence of cupric ion under high concentration of ammonia. The mode of oxidation might differ from that of ammonium thiosulfate, ammonium sulfide and elemental sulfur because of no formation of polythionate as an intermediate.