Enhanced mechanism of catalytic ozonation by ultrasound with orthogonal dual frequencies for the degradation of nitrobenzene in aqueous solution.
The experiments have been performed with a semi-continuous batch reactor to investigate the degradation efficiency of nitrobenzene in aqueous solution by ultrasound with the different orthogonal dual frequencies catalytic ozonation. The introduction of ultrasound can enhance the degradation efficiency of nitrobenzene compared to the results obtained from the processes of ozonation alone and ultrasound alone. The degradation of nitrobenzene is found to be zero-order in the two systems of ultrasound alone, and the reactions follow the pseudo-first-order kinetic model in the processes of ozone alone and ozone/ultrasound. The investigation confirms that the degradation of nitrobenzene follows the mechanism of hydroxyl radical ((*)OH) oxidation, and the enhancement function is even more pronounced in the presence of ultrasound with the greater difference between the orthogonal dual frequencies due to the obvious synergetic effect between ozone and ultrasound, which increases the utilization efficiency of ozone, and accelerates the initiation of (*)OH and the formation of H(2)O(2), resulting in the rapid formation of an increasing diversity of byproducts and the advancement degree of mineralization of total organic carbon (TOC). The oxidative byproducts have been, respectively identified in the different processes selected, including o, p, m-nitrophenols, phenol, malonic acid, 4-nitrocatechol, nitrate ion, maleic acid, oxalic acid, hydroquinone, p-quinone, 1,2,3-trihydroxy-5-nitrobenzene and acetic acid.
Zhao
Lei
L
School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090, People's Republic of China. zhaolei999999@126.com
Ma
Jun
J
Zhai
Xuedong
X
D002384:Catalysis; D009578:Nitrobenzenes / Q000737:chemistry* / Q000528:radiation effects*; D010126:Ozone / Q000737:chemistry* / Q000528:radiation effects; D011829:Radiation Dosage; D012996:Solutions; D013010:Sonication / Q000379:methods*; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000528:radiation effects; D018508:Water Purification / Q000379:methods*
D009578:Nitrobenzenes; D012996:Solutions; D014874:Water Pollutants, Chemical; D014867:Water; D010126:Ozone; C036077:nitrobenzene