Revealing the pivotal role of B/N-co-doping onto carbon nanospheres for promoted sulfamethoxazole degradation and its bio-toxicity evaluation

Abstract

The doping of hetero-atoms into carbon framework could significantly regulate and activate inherent active sites of carbon configuration, thus promoting the catalytic performance of carbon catalysts. However, the mechanisms are contradictory, more effort needs to be put into mechanism insight. Herein, we designed and synthesized B/N-co-doped carbon nanospheres (B/N-CNS) in activating peroxymonosulfate (PMS) for promoted sulfamethoxazole degradation via nonradical oxidation pathway. Fully physical characterizations highlighted that as-obtained B/N-CNS exhibited a uniform structure of nanosphere with abundant B-N bond and B-C bond at the surface, which was beneficial to attract PMS and sulfamethoxazole (SMX) via Lewis acid-base effect. Quenching tests and electron paramagnetic resonance (EPR) analysis confirmed that the co-doped B/N atoms in B/N-CNS was conducive to the selective singlet oxygen(¹O₂) generation from PMS activation. Indeed, B/N-CNS also exhibited a much higher degradation efficiency (93.12 %) and mineralization rate (73.29 %) than those of N-CNS (78.00 %, 59.39 %) and B-CNS (47.55 %, 26.20 %) on SMX degradation, respectively. In addition, Ecological Structure-Activity Relationships (ECOSAR) model also illustrated the bio-toxicity of SMX to green algae, fish and daphnid was significantly reduced to ecological environment safety standards after treatment of B/N-CNS/PMS system.