Enhanced Organic Contaminants Degradation Via Coupling Molybdenum Powder with Tripolyphosphate in Fe(Ⅱ)-Based Peroxymonosulfate Activation

Abstract

To overcome the challenges of pH application range, slow cycling of Fe(III)/Fe(II) and low oxidant activation efficiency, we propose a strategy of combining molybdenum powder (Mo) cocatalyst with sodium tripolyphosphate (STPP) to accelerate peroxymonosulfate (PMS) activation and achieve efficient degradation of acetaminophen (ACT). The ACT degradation efficiency and rate were 99.7% and 0.065 min-1, respectively, which were significantly improved compared to the system without Mo due to the abundance of active sites of Mo that accelerate the dissolved Fe species complexed with STPP. Additionally, the degradation efficiency remained above 95%, and there was only a slight change in morphology after 5 cycles, demonstrating the excellent co-catalytic performance and reusability of Mo. The several oxidizing active substances (·OH, SO4·-, 1O2, Fe(Ⅳ)) were synergistically worked for ACT removal, which were investigated the origin and activation mechanism via multiple measures. Satisfactorily, the system exhibited desirable anti-jamming capability and superiority in the removal of various contaminants. ACT degradation intermediate products were measured and proposed three degradation pathways according to the results of Liquid chromatograph-mass spectrometer (LC-MS). The development of combining Mo and STPP for organic pollutant degradation is significant in broadening the application range of PMS-AOPs in environmental remediation.

Keywords: Molybdenum powder, Co-catalyst, Sodium tripolyphosphate, Fe(III)/Fe(II) conversion, Acetaminophen degradation