Oxidation and degradation of nitrobenzene by ozone micro-nano bubbles

Abstract

The remediation of ozone oxidation to nitrobenzene (NB) contaminated groundwater has limitations such as low ozone solubility and poor gas transmission capacity. In this paper, we combine the ozone oxidation and the micro-nano bubbles (MNBs) and investigate the oxidation of the degradation of NB using a semi-continuous experimental approach. The experimental results show that the degradation efficiency of NB by ozone MNBs system (98.69%) is significantly higher than that of traditional ozone oxidation. The presence of MNBs significantly increase the rate of ·OH, ·O₂^– and ¹O₂ production compared to large bubbles produced by ozone aeration. This is due to OH^– adsorbed at the interface will accelerate the conversion of ozone to ·OH during bubble rupture. And conversion between O₃,·OH, ·O₂^– and ¹O_2。 The degradation of NB in ozone MNBs could be described by quasi-first-order kinetics. The degradation kinetics of ozone MNBs are obviously affected by the initial concentration of NB, the initial pH of the reaction system, salinity, gas species and flow rate. Oxidative degradation products (p-benzoquinone, phenol, o-nitrophenol, p-nitrophenol, aniline, acetic acid, NO₃^–, etc.) have been identified by GC–MS, IC, UV–Vis. They show that the degradation results from the attack of the aromatic ring and –NO₂ of NB through nitrification, free radicals and O₃. This research introduces a novel approach for degrading NB and offers crucial insights into the degradation of organic substances using MNBs.