N-doped microcrystalline graphite for boosting peroxymonosulfate activation with highly efficient degradation of bisphenol A

With the excellent electrical conductivity and unique structure, carbonaceous materials are expected to prepare green catalysts used in sulfate radical based advanced oxidation processes. Nevertheless, most of researches are focusing on artificial synthetic material to date, thus the studies on natural carbon materials call for attention and development. Herein, impregnation-pyrolysis method was employed by adopting the urea as an extrinsic N-dopant under 850 °C to favor C–N configuration for natural microcrystalline graphite (MG). And N element presented as pyridinic N (27.42 %), pyrrolic N (40.08 %), graphitic N (25.86 %) and nitric oxide (6.65 %) in N-doped microcrystalline graphite (NMG). In addition, the catalysis performance of MG, NMG and calcined microcrystalline graphite (CMG) was examined by the degradation of bisphenol A (BPA). The NMG system exhibited high activity in a broad pH range, and acidic conditions promote the reaction rate greatly. Based on quenching tests and electron paramagnetic resonance, the degradation mechanisms comprised radical and nonradical pathway, in which 1O2 was the dominant reactive oxidative species (ROS). This study suggested that pyridinic N, pyrrolic N, graphitic N, sp (2)-hybridized carbon structure as well as defects in NMG promoted the generation of ROS, and provides a new insight in natural carbon materials for the fabrication of new eco-friendly and highly efficient PMS activation catalysts.