Undaria pinnatifida (wakame)-derived Fe, N co-doped graphene-like hierarchical porous carbon as highly efficient catalyst for activation of peroxymonosulfate (PMS) toward degradation of tetracycline (TC)

Abstract

The use of biomass as a catalyst offers a cost-effective and efficient approach for various processes, including the activation of peroxymonosulfate (PMS) to degrade contaminants. In this study, we successfully obtained Fe and N co-doped graphene-like hierarchical porous structure carbon (Fe-N/BC) by using undaria pinnatifida (wakame) as the precursor. The Fe-N/BC catalyst was utilized to activate PMS and degrade tetracycline (TC). Characterization results demonstrated an even distribution of Fe and N on the surface of the porous structure carbon. Compared to BC@PMS and N/BC@PMS, the Fe-N/BC@PMS system exhibited excellent degradation performance, achieving an 83.9 % degradation of TC in just 5 min with an ultralow catalyst dosage (Ca = 0.05 g/L) and a high TC concentration (TC = 0.03 g/L). Furthermore, experiments on radicals quenching and electron paramagnetic resonance (EPR) analysis indicated that singlet oxygen (1O2), a non-radical species, was demonstrated as the primary reactive oxygen species (ROS). The degradation mechanical analysis suggested that zero-valent iron (Fe0), pyridinic N, graphitic N, and Fe-Nx in the Fe-N/BC were the reason for the high catalytic activity. Moreover, the degradation pathways of TC were suggested through the use of LC-MS. Additionally, the ECOSAR system was employed to assess the toxicity of the intermediate products. This study reveals the active site and its mechanism in Fe-N composite biocarbon catalysts, providing a new method for synthesizing algal biocarbon catalysts.