Ozonation of ammonia at low temperature in the absence and presence of MgO.

•The selectivity to gaseous products of single ozonation of ammonia was proved to be pH dependent.•A new and possible mechanism for single ozonation of ammonia was proposed.•Catalytic ozonation over MgO was found to be able to decompose ammonia at low temperature (0–10℃).•MgO worked as a solid alkali as well as a catalyst to facilitate ammonia oxidation.