Degradation kinetics and mechanism of trace nitrobenzene by granular activated carbon enhanced microwave/hydrogen peroxide system.
The kinetics of the degradation of trace nitrobenzene (NB) by a granular activated carbon (GAC) enhanced microwave (MW)/hydrogen peroxide (H202) system was studied. Effects of pH, NB initial concentration and tert-butyl alcohol on the removal efficiency were examined. It was found that the reaction rate fits well to first-order reaction kinetics in the MW/GAC/H202 process. Moreover, GAC greatly enhanced the degradation rate of NB in water. Under a given condition (MW power 300 W, H202 dosage 10 mg/L, pH 6.85 and temperature (60 +/- 5)degrees C), the degradation rate of NB was 0.05214 min-1when 4 g/L GAC was added. In general, alkaline pH was better for NB degradation; however, the optimum pH was 8.0 in the tested pH value range of 4.0-12.0. At H202 dosage of 10 mg/L and GAC dosage of 4 g/L, the removal of NB was decreased with increasing initial concentrations of NB, indicating that a low initial concentration was beneficial for the degradation of NB. These results indicated that the MW/GAC/H202 process was effective for trace NB degradation in water. Gas chromatography-mass spectrometry analysis indicated that a hydroxyl radical addition reaction and dehydrogenation reaction enhanced NB degradation.
College of Environmental Science and Engineering Guilin University of Technology, Guilin 541004, China. dinah88@163.com
Dina
D
Tan
Honghu
H
Zeng
Jie
J
Liu
Xiaozhang
X
Yu
Yanpeng
Y
Liang
Lanjing
L
Lu
D002244:Carbon / Q000737:chemistry* / Q000528:radiation effects; D006861:Hydrogen Peroxide / Q000737:chemistry* / Q000528:radiation effects; D007700:Kinetics; D008872:Microwaves; D009578:Nitrobenzenes / Q000737:chemistry* / Q000528:radiation effects; D016877:Oxidants / Q000737:chemistry* / Q000528:radiation effects; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000528:radiation effects; D018508:Water Purification / Q000379:methods
D009578:Nitrobenzenes; D016877:Oxidants; D014874:Water Pollutants, Chemical; D002244:Carbon; D006861:Hydrogen Peroxide; C036077:nitrobenzene