Removal performance and mechanism of aniline from landfill leachate by ozone oxidation process using iron-based packed catalyst.

Aniline in landfill leachate was used as a target pollutant and treated by a catalytic ozonation process (COP). The catalyst was based on waste iron shavings, which were oxidatively modified to form an iron-based ozonation catalyst (FOC), and subsequently compressed into an iron-based packing for catalyzing the ozonolysis of aniline (FCOP). The special porous structure of the compressed packing material enhanced the decomposition of O3. FCOP achieved 93% removal of aniline from the simulated wastewater, which was significantly better than the ozonation alone process (OOP). At low pH (<3), the removal of aniline relied on the endo-Fenton mechanism due to the presence of Fe2+ and H2O2. At high pH (>5), aniline was removed by the COP mechanism. At the FOC surface, electron transfer facilitated ozonolysis to produce •OH radicals, which simultaneously produced Fe2+ oxidation and Fe3+ reduction, establishing a redox cycle. The main role of -OH in the FCOP system and the aniline degradation pathway were determined using EPR and related techniques. FCOP is a cost-effective and environmentally friendly process that can be used to treat aniline in the future.