The degradation of p-nitrotoluene by O3/H2O2 process in a bubble contact column was investigated. Effects of the molar ratio of hydrogen peroxide to ozone,pH value and t-butanol on the oxidation process were discussed...The degradation of p-nitrotoluene by O3/H2O2 process in a bubble contact column was investigated. Effects of the molar ratio of hydrogen peroxide to ozone,pH value and t-butanol on the oxidation process were discussed. It was found that the proper H2O2/O3 molar ratio for the degradation of p-nitrotoluene was around 0.6, different pH values and the presence of t-butanol highly influenced the removal efficiency of p-nitrotoluene. 5-methyl-2-nitrophenol, 2-methyl-5-nitrophenol, (4-nitrophenyl) methanol, 5-(hydroxymethyl)-2-nitro phenol, acetic acid, 2-methylpropane diacid and 2-(hydroxylmethyl)propane diacid were identified as degradation intermediates and products through GC-MS. Radical reaction mechanism and degradation pathway were proposed based on the results of experiments. It is deduced that the benzene ring of p-nitrotoluene can be only destroyed by hydroxyl radicals through a polyhydroxy intermediate pathway. Then unstable polyhydroxy intermediates can be oxidized to different acids with low molecular weight rapidly.展开更多
The oxidation of pnitrotoluene with electro-generated superoxide ion in the presence or absence of metallo-porphyrins FeTPP, MnTPP and CoTPP in DMF was studied by cyclic voltammetry and controlled potential electrolys...The oxidation of pnitrotoluene with electro-generated superoxide ion in the presence or absence of metallo-porphyrins FeTPP, MnTPP and CoTPP in DMF was studied by cyclic voltammetry and controlled potential electrolysis, Metallo-porphyrins as catalysts for electroreduction of O_2, they can not only increase yields of p-nitrobensoic acid and selectivities of reaction but also enable the reaction proceed at lower negative potential.展开更多
2024年3月,依据“未来导航”(FutureNAV)计划,欧洲航天局(ESA)与多家欧洲航天公司签署了总金额为2.33亿欧元的合同,用于开发“创世”(GENESIS)和“低地球轨道定位、导航与授时”(LEO-PNT)演示卫星,以增强卫星导航和新的地球测绘能力。其...2024年3月,依据“未来导航”(FutureNAV)计划,欧洲航天局(ESA)与多家欧洲航天公司签署了总金额为2.33亿欧元的合同,用于开发“创世”(GENESIS)和“低地球轨道定位、导航与授时”(LEO-PNT)演示卫星,以增强卫星导航和新的地球测绘能力。其中,GENESIS合同价值为7660万欧元,由不来梅轨道高科技系统公司意大利分公司(OHB Italia SpA)牵头,包括意大利、比利时、法国、瑞士、英国、匈牙利等国家的14个实体机构负责有效载荷及卫星的开发、制造、鉴定、校准、发射和卫星运营。展开更多
从导航增强与弹性定位、导航和授时(Positioning,Navigation and Timing,PNT)两个方向,系统阐述基于低轨星座的PNT性能提升能力,包括全球天基监测、全球准实时高精度、可信认证、弹性应急备份等。综合国内外低轨星座发展现状,分析了低...从导航增强与弹性定位、导航和授时(Positioning,Navigation and Timing,PNT)两个方向,系统阐述基于低轨星座的PNT性能提升能力,包括全球天基监测、全球准实时高精度、可信认证、弹性应急备份等。综合国内外低轨星座发展现状,分析了低轨星座实现PNT性能提升的两种实现途径:一是在导航频段播发信号实现性能提升,可与现有各全球卫星导航系统(Global Navigation Satellite System,GNSS)实现良好的兼容与互操作性能;二是利用通信频段播发导航通信(导通)融合信号,实现与现有导航频段信号的弹性应急备份。二者均可实现定位精度及其收敛时间、完好性、安全性等性能提升,但因信号频段和业务类型差异,两者的技术体制、实现能力和代价有所不同。为此,文章从星载接收与处理技术、导航增强和导通融合信号体制设计、同时同频收发干扰抑制技术、弹性终端融合接收处理技术等方面,分析了实现导航增强和弹性PNT服务的关键技术,最后给出了基于低轨星座的PNT性能提升的发展建议。文章的研究成果,有助于进一步探索低轨星座的潜力,促进全球卫星导航系统的发展,并为低轨PNT性能提升技术的研究和应用提供参考。展开更多
基金Sponsored by the National Natural Science Foundation of China(Grant No.50378028)
文摘The degradation of p-nitrotoluene by O3/H2O2 process in a bubble contact column was investigated. Effects of the molar ratio of hydrogen peroxide to ozone,pH value and t-butanol on the oxidation process were discussed. It was found that the proper H2O2/O3 molar ratio for the degradation of p-nitrotoluene was around 0.6, different pH values and the presence of t-butanol highly influenced the removal efficiency of p-nitrotoluene. 5-methyl-2-nitrophenol, 2-methyl-5-nitrophenol, (4-nitrophenyl) methanol, 5-(hydroxymethyl)-2-nitro phenol, acetic acid, 2-methylpropane diacid and 2-(hydroxylmethyl)propane diacid were identified as degradation intermediates and products through GC-MS. Radical reaction mechanism and degradation pathway were proposed based on the results of experiments. It is deduced that the benzene ring of p-nitrotoluene can be only destroyed by hydroxyl radicals through a polyhydroxy intermediate pathway. Then unstable polyhydroxy intermediates can be oxidized to different acids with low molecular weight rapidly.
文摘The oxidation of pnitrotoluene with electro-generated superoxide ion in the presence or absence of metallo-porphyrins FeTPP, MnTPP and CoTPP in DMF was studied by cyclic voltammetry and controlled potential electrolysis, Metallo-porphyrins as catalysts for electroreduction of O_2, they can not only increase yields of p-nitrobensoic acid and selectivities of reaction but also enable the reaction proceed at lower negative potential.
文摘2024年3月,依据“未来导航”(FutureNAV)计划,欧洲航天局(ESA)与多家欧洲航天公司签署了总金额为2.33亿欧元的合同,用于开发“创世”(GENESIS)和“低地球轨道定位、导航与授时”(LEO-PNT)演示卫星,以增强卫星导航和新的地球测绘能力。其中,GENESIS合同价值为7660万欧元,由不来梅轨道高科技系统公司意大利分公司(OHB Italia SpA)牵头,包括意大利、比利时、法国、瑞士、英国、匈牙利等国家的14个实体机构负责有效载荷及卫星的开发、制造、鉴定、校准、发射和卫星运营。
