Carbonized polyaniline activated peroxymonosulfate (PMS) for phenol degradation: Role of PMS adsorption and singlet oxygen generation

N-doped carbonaceous materials are promising efficient catalysts for peroxymonosulfate (PMS) activation. In this study, the high-efficient N-doped carbon materials were prepared by direct carbonization of polyaniline (PANI) at 700 °C–1000 °C. It was optimized that the CPANI-9 (carbonized polyaniline prepared at 900 °C) exhibited excellent catalytic performance to activate PMS for phenol degradation, which was efficient over a wide pH range (pH 3.5∼9). In the CPANI-9/PMS system, the PMS adsorption/activation was identified as the key step determining the reaction rate. The quenching experiments and electron paramagnetic resonance demonstrated that the non-radical pathway was dominant in phenol degradation and singlet oxygen (1O2) was the main active specie. Graphitic N, pyridinic N, defects and ketonic groups (CO) were identified as catalytic sites. Interestingly, only the presence of PO43− greatly decreased the phenol degradation rate and PMS decomposition. The CPANI-9/PMS system could also degrade effectively various organic pollutants, indicating that it had potential practical application.