Carbonized polyaniline-activated peracetic acid advanced oxidation process for organic removal: Efficiency and mechanisms

Recently, advanced oxidation processes (AOPs) based upon peracetic acid (PAA) with high efficiency for degrading aqueous organic contaminants have attracted extensive attention. Herein, a novel metal-free N-doped carbonaceous catalyst, namely, carbonized polyaniline (CPANI), was applied to activate PAA to degrade phenolic and pharmaceutical pollutants. The results showed that the CPANI/PAA system could effectively degrade 10 μM phenol in 60 min with low concentrations of PAA (0.1 mM) and catalyst (25 mg L−1). This system also performed well within a wide pH range of 5–9 and displayed high tolerance to Cl−, HCO3− and humic acid. The nonradical pathway [singlet oxygen (1O2)] was found to be the dominant pathway for degrading organic contaminants in the CPNAI/PAA system. Systematic characterization revealed that the graphitic N, pyridinic N, carbonyl groups (CO) and defects played the role of active sites on CPANI during the activation of PAA. The catalytic capacity of spent CPANI could be conveniently recovered by thermal treatment. The findings will be helpful for the application of metal-free carbonaceous catalyst/PAA processes in decontaminating water. •Peracetic acid could be activated efficiently by a metal-free N-doped carbon material.•High degradation efficiency of phenol was observed in a wide pH range of 5–9.•1O2 was the primary reactive species while HO.• and R–C• were the minor ones.•The graphitic N, pyridinic N, carbonyl groups and defects were the reactive sites for 1O2 generation.