Recovery of ammonia and nitrate ion from ammonium nitrate in waste water by steam distillation adding lead(II) oxide

Recovery of NH3 and NO3- from concentrated NH4NO3 solutions was studied. Lead(II) oxide was added to 0.1-2 M NH4NO3 solutions at 373 K to precipitate basic lead(II) nitrates and to recover NH3 simultaneously by steam distillation for 0.25-2 h. The effects of the molar ratio of PbO/NO3- and steam distillation time on the removal of NO3- and the recovery of NH3, and on the composition of basic lead(II) nitrate were examined. The removal of NO3- as Pb(NO3)(2) . 5Pb(OH)(2) and the recovery of NH3 reached about 100% at a PbO/NO3- molar ratio of 4 for 1 h. Above 0.5 M NH4NO3, the removal of NO3- was independent of the initial concentration of NO3-. Since the recovery of NH3 was analogous to the removal of NO3-, effective removal of NH3 was important to precipitate nitrate ion as basic lead(II) nitrates. Under the experimental conditions, basic lead(II) nitrates, 2Pb(NO3)(2) . 5Pb(OH)(2), Pb(NO3)(2) . 3Pb(OH)(2) and Pb(NO3)(2) . 5Pb(OH)(2) were formed in single phase or mixed phase.