The kinetics of thedegradation of trace nitrobenzene （NB） by a granular activated carbon （GAC） enhanced microwave （MW）/hydrogen peroxide （H202 ） systemwas studied. Effects of pH, NB initial concentration and t...The kinetics of thedegradation of trace nitrobenzene （NB） by a granular activated carbon （GAC） enhanced microwave （MW）/hydrogen peroxide （H202 ） systemwas studied. Effects of pH, NB initial concentration and tert-butyl alcohol on the removal efficiencywere examined. Itwas found that the reaction rate fitswell to first-order reaction kinetics in the MW/GAC/H202 process. Moreover, GAC greatly enhanced thedegradation rate of NB inwater. Under a given condition （MW power300 W, H202dosage 10 mg/L, pH 6.85 and temperature （60 ± 5）°C）, thedegradation rate of NBwas 0.05214 min 1when4 g/L GACwas added. In general, alkaline pHwas better for NBdegradation; however, the optimum pHwas 8.0 in the tested pH value range of4.0-12.0. At H202dosage of 10 mg/L and GACdosage of4 g/L, the removal of NBwasdecreasedwith increasing initial concentrations of NB, indicating that a low initial concentrationwas beneficial for thedegradation of NB. These results indicated that the MW/GAC/H202 processwas effective for trace NBdegradation inwater. Gas chromatography-mass spectrometry analysis indicated that a hydroxyl radical addition reaction anddehydrogenation reaction enhanced NBdegradation.展开更多
To evaluate possible use of microwave- enhanced H2O2-based （MW/H2O2） process to degrade trace nitrobenzene （NB） in water, a series of batch experiments were conducted. The results showed that 2450MHz microwave irr...To evaluate possible use of microwave- enhanced H2O2-based （MW/H2O2） process to degrade trace nitrobenzene （NB） in water, a series of batch experiments were conducted. The results showed that 2450MHz microwave irradiation significantly enhanced oxidative decomposition of nitrobenzene （NB） in a H2O2 system. About 90% NB was degraded by the MW/H2O2 process in 30 min. Moreover, the MW/H2O2 process could enhanced the oxidative degradation of NB even at relatively low temperature （50℃）. When the initial concentration of NB was 300gg/L, the optimum ratio of H2O2 to NB and MW power were 70 and 300W respectively. The presence of humic acid significantly increased H2O2 dosage. The ultraviolet absorbance at 254 nm （UV254） indicated degradation of NB was stepwise and some intermediates were produced. The gas chromatography-mass spectrometric （GC-MS） analysis showed that main intermediates were nitrophenolic and carbonyl compounds.展开更多
基金supported by the National Natural Science Foundation of China(No.51268008,21207024)the Key Project of Chinese Ministry of Education(No.210170,JiaoJiSi[2010]114)+1 种基金the Program for Excellent Talentsin the Guangxi Higher Education Institutions(No.Gui-JiaoRen[2010]65)the Guangxi Scientific Research and Technological Development Plan(No.GuiKeZhuan1298009-17)
文摘The kinetics of thedegradation of trace nitrobenzene （NB） by a granular activated carbon （GAC） enhanced microwave （MW）/hydrogen peroxide （H202 ） systemwas studied. Effects of pH, NB initial concentration and tert-butyl alcohol on the removal efficiencywere examined. Itwas found that the reaction rate fitswell to first-order reaction kinetics in the MW/GAC/H202 process. Moreover, GAC greatly enhanced thedegradation rate of NB inwater. Under a given condition （MW power300 W, H202dosage 10 mg/L, pH 6.85 and temperature （60 ± 5）°C）, thedegradation rate of NBwas 0.05214 min 1when4 g/L GACwas added. In general, alkaline pHwas better for NBdegradation; however, the optimum pHwas 8.0 in the tested pH value range of4.0-12.0. At H202dosage of 10 mg/L and GACdosage of4 g/L, the removal of NBwasdecreasedwith increasing initial concentrations of NB, indicating that a low initial concentrationwas beneficial for thedegradation of NB. These results indicated that the MW/GAC/H202 processwas effective for trace NBdegradation inwater. Gas chromatography-mass spectrometry analysis indicated that a hydroxyl radical addition reaction anddehydrogenation reaction enhanced NBdegradation.
基金The authors thank the financial support from the Critical Patented Projects in the Control and Management of the National Polluted Water Bodies （No. 2008ZX07317-02-03E）, the Key Science Research Projects of Ministry of Education of China and the Provincial Natural Science Foundation of Guangxi （No. Guikegung 0992008-3, Guikeqing 0640070）.
文摘To evaluate possible use of microwave- enhanced H2O2-based （MW/H2O2） process to degrade trace nitrobenzene （NB） in water, a series of batch experiments were conducted. The results showed that 2450MHz microwave irradiation significantly enhanced oxidative decomposition of nitrobenzene （NB） in a H2O2 system. About 90% NB was degraded by the MW/H2O2 process in 30 min. Moreover, the MW/H2O2 process could enhanced the oxidative degradation of NB even at relatively low temperature （50℃）. When the initial concentration of NB was 300gg/L, the optimum ratio of H2O2 to NB and MW power were 70 and 300W respectively. The presence of humic acid significantly increased H2O2 dosage. The ultraviolet absorbance at 254 nm （UV254） indicated degradation of NB was stepwise and some intermediates were produced. The gas chromatography-mass spectrometric （GC-MS） analysis showed that main intermediates were nitrophenolic and carbonyl compounds.
