Protonated Hydroxylamine-Assisted Iron Catalytic Activation of Persulfate for the Rapid Removal of Persistent Organics from Wastewater

This research aims at optimizing the effects of processing conditions, salts, natural organic materials, and water matrices quality on the effectiveness of the Fe(II)/K₂S₂O₈/hydroxylamine process in the degradation of pararosaniline. Assisting the Fe(II)/KPS (potassium persulfate) treatment with protonated hydroxylamine (H₃NOH⁺) increases the degradation rate of pararosaniline by more than 100%. Radical scavenger experiments show that the SO₄^●? radical dominates pararosaniline degradation in the Fe(II)/KPS system, whereas ^●OH is the dominant reactive species in the presence of H₃NOH⁺. The disparity in pararosaniline removal effectiveness upon the Fe(II)/KPS/H₃NOH⁺ and Fe(II)/KPS systems gets more significant with increasing reactants doses (i.e., H₃NOH⁺, H₂O₂, Fe(II)) and solution pH (2–7). Interestingly, H₃NOH⁺ increased the working pH to 6 instead of pH 4 for the Fe(II)/KPS process. Moreover, mineral anions such as Cl^?, NO₃^?, NO₂^?, and SO₄^? (up to 10 × 10^?3 m ) do not affect the efficiency of the Fe(II)/KPS/H₃NOH⁺ process. In contrast, acid humic decreases the performance of the process by ≈20%. In natural mineral water, treated wastewater, and river water samples, the Fe(II)/KPS/H₃NOH⁺ process maintains higher degradation performance (≈95%), whereas the process efficiency is greatly amortized in seawater. The efficiency of the Fe(II)/KPS process was drastically decreased in the various water matrices.