Degradation of p-Nitrophenol by Nanoscale Zero-Valent Iron Produced by Microwave-Assisted Ball Milling

Abstract

The applicability of microwave-assisted ball milling for the treatment of p-nitrophenol (PNP) was investigated in this study. The degradation process of PNP was studied by using UV-vis (ultraviolet-visible) spectra, total organic carbon (TOC), fluorescence intensities, electroconductivity, and X-ray diffraction (XRD). PNP was degraded 99.1% after microwave-assisted ball milling for only 15 min at pH 3 when the initial concentration of PNP was 3 mg/L. When the pH value of solution was 3, PNP can be mineralized completely in 12 min by microwave-assisted ball milling and adding hydrogen peroxide. The new high-activity nanoscale zero-valent iron (NZVI) was produced constantly in the process of stirring, collision, and spalling, preventing nanoparticles from reuniting. Further, the hydroxyl radical generated in the coupling effect of microwave and mechanical force also improved the reaction rate.