Nano-MoO activates peroxymonosulfate for the degradation of PAH derivatives.

The rapid and efficient degradation of polycyclic aromatic hydrocarbon (PAH) derivatives with toxicological properties remains a substantial challenge. In this study, a cost-effective and eco-friendly catalyst, nano-MoO (0.05 g L), exhibited excellent performance in activating 4.0 mmol L peroxymonosulfate (PMS) for the degradation of naphthalene derivatives with 1 mg L in aqueous systems; these derivatives include 1-methylnaphthalene, 1-nitronaphthalene, 1-chloronaphthalene, 1-naphthylamine and 1-naphthol, with high degradation rates of 87.52%, 86.23%, 97.87%, 99.74%, and 77.16%. Nano-MoO acts as an electron donor by transferring an electron causing O-O bond of PMS to cleave producing SO, and later OH. Electron paramagnetic resonance (EPR) analysis combined with free radical quenching research indicated that SO and OH dominated the degradation of naphthalene derivatives, and O and O participated in the processes. X-ray photoelectron spectroscopy (XPS) revealed the transformation of Mo(IV) to Mo(V) and Mo(VI), which suggested that the activation process proceeded via electron transfer from nano-MoO to PMS. The applicability of the nano-MoO/PMS system in influencing parameters and stability was explored. The degradation pathways were primarily elucidated for each naphthalene derivative based on the intermediates identified in the systems. The -CH, -NO, -Cl, -OH substituents increased the positive electrostatic potential (ESP) on the molecular surface of 1-methylnaphthalene, 1-nitronaphthalene, 1-chloronaphthalene, and 1-naphthol, which reduced the electrophilic reaction and electron transfer between the reactive species and pollutants, leading to a lower degradation rate of naphthalene derivatives than the parent compound. However, the effect of -NH substituents is the opposite. These findings suggest that nano-MoO may aid as a novel catalyst in the future remediation of environments polluted with PAH derivatives.