Plant-Cell mediated synthesis of MnCo2O4 nanoparticles and their activation of peroxymonosulfate to remove Tetracycline

Nanosized bimetallic oxides can efficiently activate peroxymonosulfate (PMS) to degrade organic pollutants attributed to their synergetic electron transfer between the two metals. However, their scalable and controllable synthesis remains challenging. In this study, small and regular MnCo2O4 nanoparticles (NPs) were successfully synthesized via a facile bio-templating method. Leaf cells were used as structure-directing agents, and the nucleation and growth of MnCo2O4 were restricted in the confined space of cells, resulting in MnCo2O4 spinel with an average size of 22 nm. The MnCo2O4 NPs can activate PMS to achieve 99 % degradation of TC (C-0 = 20 mg<middle dot>L-1) within 10 min. Moreover, the MnCo2O4 NPs also show a wide applicable pH range (3.0 - 11.0, RE > 94 %), excellent reusability (RE = 96 % after four cycles), and good adaptability in the complex water matrix. Analysis of the catalytic mechanisms suggests that radical O-2(center dot-) and non-radical O-1(2) dominate this MnCo2O4 + PMS + TC system. Besides, 17 major degradation intermediates of TC were identified (most of them were predicted to be harmless), and 3 possible degradation pathways were proposed. This study provides a feasible strategy for synthesizing spinel-structured MnCo2O4 NPs, which show great potential in removing antibiotics from wastewater.