Degradation and mineralization of aniline by O 3 /Fenton process enhanced using high-gravity technology

Abstract

The degradation and mineralization of aniline (AN) using ozone combined with Fenton reagent (O3/Fenton) in a rotating packed bed (RPB) was proposed in this study, and the process (RPB-O3/Fenton) was compared with conventional O3/Fenton in a stirred tank reactor (STR-O3/Fenton) or single ozonation in an RPB (RPB-O3). Effects of high gravity factor, H2O2 dosage, H2O2 dosing method and initial pH on the AN mineralization efficiency were investigated in the RPB-O3/Fenton process. In addition, the behavior of Fe(II) was monitored at different H2O2 dosing methods and pH values. Finally, the optimal operation conditions were determined with high gravity factor of 100, initial pH of 5, Fe(II) concentration of 0.8 mmol·L− 1 and H2O2 dosage of 2.5 ml. Under these conditions, for aniline wastewater at the volume of 1 L and concentration of 200 mg·L− 1, a fast and thorough decay of AN was conducted in 10 min, and the TOC removal efficiency reached 89% in 60 min. The main intermediates of p-benzoquinone, nitrobenzene, maleic acid and oxalic acid were identified by liquid chromatography/mass spectroscopy (LC/MS), and the degradation pathways of AN in RPB-O3/Fenton system were proposed based on experimental evidence. It could be envisioned that high-gravity technology combined with O3/Fenton processes would be promising in the rapid and efficient mineralization of wastewater.