Mo and Mo bimetallic reactive sites accelerating Fe/Fe cycling for the activation of peroxymonosulfate with significantly improved remediation of aromatic pollutants.

In Fe/peroxymonosulfate (PMS) activation system, the slow cycle rate of Fe/Fe has been considered to be the limiting step in the remediation of organic contaminants. In this paper, commercial molybdenum (Mo) powder is employed as the cocatalyst in Fe/PMS system, which can significantly accelerate the Fe/Fe cycling efficiency by the exposed bimetallic active sites of Mo and Mo, and the process is accelerated as the amount of Mo powder increased. The Mo cocatalytic Fe/PMS system exhibits an enhanced performance for the activation of PMS and the removal of different aromatic pollutants including dyes, phenolic pollutants and antibiotics, in a wide pH range of 4.0-9.0. Importantly, Mo powder exhibits excellent cycle performance in the PMS activation system, and rhodamine B (RhB) can be removed within 10 min even after 5 cycles. Electron paramagnetic resonance (EPR) prove that the sulfate radicals (SO) is the major reactive oxides species in the PMS activation, the increase of Fe content induced by the cocatalytic effect of Mo powder can effectively promote the production of SO and increase the utilization of PMS. In addition, to observe the process of pollutant removal more intuitively, HPLC-MS is used to analyze the decomposing pathway of RhB and sulfadiazine in Mo+FeSO+PMS system. It is believed that this research provides a new idea for the efficient activation of PMS by iron ions in a wide initial pH range, which is expected to be applied to the treatment of large-scale industrial wastewater.