Efficient pH-universal degradation of antibiotic tetracycline via Co2P decorated Neosinocalamus affinis biochar

Abstract

Considering the complexity of traditional cobalt phosphide (Co₂P) loaded biochar synthesis research on a simple and efficient synthesis method has practical significance. In this study, after phosphoric acid activation, Neosinocalamus affinis biochar (NAB) and nanoplate Co₃O₄ quickly formed a Co₂P-NAB composite material with high Co₂P crystallinity and was uniformly dispersed on the surface of NAB in a microwave reactor. Co₂P-NAB has an excellent catalytic degradation effect in the activation of peroxymonosulfate (PMS) to degrade tetracycline (TC). The optimal TC degradation efficiency was achieved with the addition of 50 mg L^-1 TC concentration, 0.2 g L^-1 catalysts, 0.406 mM PMS and pH = 6.02. In addition, according to the pseudo-first-order reaction rate constant calculation, the composite of Co₂P-NAB and PMS the synergy efficiency is 81.55 %. Compared with Co₂P-NAB (10.83 %) and PMS (7.62 %) alone, the Co₂P-NAB/PMS system has a significant promotion effect on the degradation of TC molecules. Additionally, the Co₂P-NAB/PMS system had a TC mineralization rate of 68 % in 30 min. Furthermore, after a series of characterization, detection and analysis, and influencing factor experiments, we proposed a potential mechanism for the Co₂P-NAB/PMS reaction system to degrade TC and found that singlet oxygen (¹O₂) plays an essential role in the non-radical degradation process. Finally, according to the liquid chromatography-mass spectrometry (LC-MS) detection of TC degradation intermediates, a possible degradation route was proposed. Therefore, this work uses microwave technology to present a novel and simple synthesis method for transition metal phosphides, which provides potential application value for the treatment of actual wastewater with heterogeneous catalysts.

Keywords: Cobalt phosphide; Microwave synthesis; Peroxymonosulfate activation; Tetracycline degradation.