硝酸尾气中氮氧化物含量的分析研究

氮氧化物气体被氧气完全氧化成二氧化氮,用氨水吸收,盐酸萘乙二胺分光光度法检测硝酸尾气中NOx的含量.     

对二氧化氮气体快速检测方法的研究

研究一种简便、快速监测二氧化氮气体的方法,即二氧化氮被动式检气管法。主要结合气体分子扩散原理和化学吸收原理,在检气管内装有浸渍过显色剂的载体,检气管处于有二氧化氮气体的环境中,在一定时间内,两端载体发生一定长度的显色反应。根据时间和显色长度可求出环境中二氧化氮的浓度。该检气管集采样与分析为一体,可以快速测定二氧化氮气体的浓度,经应用实验表明,具有较高的灵敏度,基本上达到设计要求。     

液态二氧化氮储罐泄漏引起中毒的影响分析

叙述了二氧化氮的来源、用途及其危险特性,分析了液态二氧化氮泄漏后引起中毒事故的扩散模型。并以具体工程实例,分析出二氧化氮泄漏后引起中毒的伤害程度及影响半径,提出了预防和防止二氧化氮泄漏的安全措施,以及泄漏后采取的安全处理措施。最后,综述了对液态二氧化氮中毒事故模型分析所具有的重要意义。     

2013年石家庄市空气质量情况及污染成因分析

文章对2013年石家庄市7个自动监测点的环境空气质量的检测数据进行了分析,得出石家庄市首要污染物为细颗粒物和可吸入颗粒物.二氧化硫、二氧化氮、细颗粒物和可吸入颗粒物的变化趋势是冬季高,春夏秋低.燃煤、机动车尾气、建筑扬尘是石家庄市大气污染的三大污染源,大气污染防治必须严抓二氧化硫、二氧化氮、细颗粒物和可吸入颗粒物这四类污染物,不断减少污染物的排放.     

NO_2催化氧化合成己二酸的研究

以二氧化氮为氧化剂,自制吸收塔为反应发生器,通过催化氧化环己醇合成了己二酸。用红外光谱、核磁共振对合成产物的结构进行表征,由结果可知合成产物为己二酸;采用单因素法考察了反应温度、反应时间、二氧化氮气体流速等因素对己二酸收率的影响,优化了合成反应条件。最佳实验条件为:二氧化氮气体流速0.3 L/min,反应温度50—60℃,反应时间6 h,此条件下己二酸的收率可达87.4%,环己醇对二氧化氮的平均吸收率为98.9%。另外,本方法还为二氧化氮的回收利用提供了一种新的途径。     

糖精钠生产过程中废气的回收利用研究与探讨

在糖精生产过程中有氨气、氯化氢、二氧化氮、二氧化硫等废气放出。其中氨气用水吸收生成的氨水可吸收氯化氢、二氧化氮,所得溶液经处理可制成氮肥再利用;二氧化硫气体经洗涤后,用柠檬酸钠缓冲溶液吸收,再经解析、干燥、压缩后得到二氧化硫液体,然后供生产使用。     

分光光度法测定工作场所空气中二氧化氮浓度的不确定度评定

对盐酸萘乙二胺分光光度法测定工作场所空气中二氧化氮浓度进行不确定度评定。分析测定过程中不确定度的来源,包括测量重复性的不确定度、标准溶液配制的不确定度、标准曲线变动性的不确定度、采集样品的不确定度、采样效率的不确定度以及仪器重复性的不确定度。确定各不确定度分量值,给出了工作场所空气中二氧化氮浓度测量的合成标准不确定度和扩展不确定度,为准确评价工作场所空气中二氧化氮浓度提供依据。     

芳烃甲苯的催化选择性硝化

研究分子印迹聚合物催化剂在甲苯二氧化氮硝化反应的催化特性.应用酸性基团的聚合物单体制得的MIP具有较好的催化性能,在乙腈溶剂中甲苯二氧化氮硝化反应区域选择性达到90%以上.     

电镀工厂废气治理

从大气污染的角度看,电镀行业和一些主要的引起大气污染的行业如电力、冶金、化工等相比,它的排放量小得多,排放污染物的品种较少,其影响通常只限于电镀工厂周围的局部地区。我国目前电镀行业排放的大气污染物质主要是由硝酸分解产生的氧化氮,氧化氮有毒,对人体与环境有害。这里指的氧化氮包括一氧化氮与二氧化氮。一氧化氮是无色气体,二氧化氮则是红棕色的气体。电镀厂排放的氧化氮中以二氧化氮居多,因此俗称黄龙。虽然废气数     

Kyodai硝化法合成1-硝基金刚烷

将二氧化氮-臭氧体系用于金刚烷的直接硝化合成重要中间体1-硝基金刚烷,研究二氧化氮用量、反应时间、反应温度和臭氧流量等因素对反应的影响,在n（金刚烷）：n（二氧化氮）=1：15、臭氧流量为0．4L／min、-30℃下反应2h的优化条件下,金刚烷的转化率为99．9％,1-硝基金刚烷的收率为90．9％,当n（金刚烷）：n（二氧化氮）=1：30时,1-硝基金刚烷的收率可达92．1％。     

环境空气中二氧化氮测定的不确定度评定

对Saltzman法测定环境空气中二氧化氮含量的不确定度进行评定,通过对测量过程重复性、所用的计量玻璃量器、标准溶液的浓度、标准曲线的绘制、采样体积和吸收液体积等影响测定结果的不确定度分量进行分析,找出影响测量结果的关键因素,对进一步优化测试方法,提高实验的准确度有重要意义。     

盐酸萘乙二胺分光光度法测定大气中二氧化氮的浓度

本文介绍了盐酸萘乙二胺分光光度法测定大气中NO2的浓度,本方法的检出限为0.018Iμg·mL-1,最低检出浓度为0.009mg·m-3,测定范围为0.018～0.7 μg·mL-1,相对标准偏差1.3%～3.4%,采样效率为98.4%.     

Capture of Nitrogen Oxides with a Fibre Chemisorbent

A system for cleaning nitrogen oxides from a gas-air mixture was proposed. The degree of sorption of nitrogen dioxide is determined by the rate of passage of the gas–air mixture through the filter and its concentration. Weakly basic VION AN-1 fibre treated with 3% sodium hydroxide solution was used as the chemisorbent. A hypothesis was advanced concerning the chemistry of capture of nitrogen dioxide by weakly basic VION AN-1 fibre treated with 3% sodium hydroxide solution.     

Headspace gas analysis of salad oils by mass spectrometry

A mass spectrometer was used to analyze the content of hydrogen, nitrogen, oxygen, carbon dioxide and argon in headspace gas of commercially packaged soybean, cottonseed and corn salad oils. A leakproof sampling system was designed to avoid air contamination and obtain a representative headspace gas sample. Some edible oils are packaged under pure nitrogen, whereas other samples contained various amounts of oxygen in the headspace gas. The presence or absence of argon in the headspace gas indicates that some oils are packaged with pure nitrogen and others with nitrogen obtained by controlled burning of hydrocarbons to remove all the oxygen in air. The presence of hydrogen in some samples where argon was also present suggested that catalytic purifiers were used to remove the last traces of oxygen and to ensure pure nitrogen for packaging oils. The decrease in oxygen of oils bottled in air was followed during storage at room and at elevated temperatures. No. Market. and Nutr. Res. Div., ARS, USDA.     

The reaction of low levels of nitrogen dioxide with methyl linoleate in the presence and absence of oxygen

The reaction of methyl linoleate with low levels of nitrogen dioxide in a carrier gas, such as helium or air, at nitrogen dioxide concentrations ranging from 2 to 228 ppm was studied and the products formed were monitored. In both aerobic and anaerobic conditions, low concentrations of nitrogen dioxide reacted with methyl linoleate predominately to form allylic products. When a 1∶1 mixture of methyl palmitate/methyl linoleate was layered over an aqueous buffer and a nitrogen dioxide stream was passed from underneath, so that the stream passed through the aqueous layer before contacting the organic layer, allylic products again predominated. In the absence of air, the allylic products consisted of allylic nitro and nitrite derivatives of linoleate, whereas in the presence of air, allylic hydroperoxides were the principal products. The findings suggest that fatty acids with doubly allylic hydrogen atoms react preferentially by a hydrogen atom abstraction reaction rather than by the addition of nitrogen dioxide to a double bond.     

我国变压吸附技术的工业应用现状及展望

介绍了我国变压吸附技术近十多年发展状况及变压吸附技术在各应用领域的最新发展,并对今后的应用和发展作了展望。     

Ethylene recovery from low grade gas stream by adsorption on zeolites and controlled desorption

Carbon dioxide was partially removed from a nitrogen stream, which also contained some ethylene, by adsorption on a 4A (Na-A) zeolite. The treated nitrogen stream was then passed over a 13X (Na-X) zeolite bed upon which ethylene and any remaining carbon dioxide were adsorbed. Ethylene was recovered by desorption at 68 Pa pressure into a slow flow of nitrogen as stripping gas. The ethylene concentration in the extracted gas was extremely dependent on the nitrogen flow-rate, whereas the concentration of carbon dioxide remained practically constant. Thus, it was possible to obtain a gas mixture greatly enriched in ethylene with a reasonably low content of carbon dioxide.     

Determining the carbon dioxide permeability of paint films

An in-house set-up was developed for determining the permeability of, paint films towards carbon dioxide. The system implemented the so-called Wicke-Kallenback method, described in EN 1062-6. This method consists of a two-chamber permeation cell divided by a supported paint film. A carbon dioxide/nitrogen mixture stream (15% CO₂/85% N₂) is fed to the retentate chamber and a nitrogen carrier stream is fed to the permeate chamber. Carbon dioxide permeates from the retentate to the permeate chamber. The carbon dioxide flow rate is obtained from the permeate concentration and flow rate. From the carbon dioxide flow rate it is possible to calculate the paint film permeability towards this gas. The coating system is applied on a Kraft paper support sheet; the Kraft paper by itself shows negligible permeation, resistance. Coatings to be considered as “surface protection systems for concrete” must comply with EN 1504-2. This standard requires that the paint film permeability have an equivalent air thickness of S_D≥50 m. The unit developed was able to quickly determine permeabilities as low as an equivalent air thickness of S_D=1500 m.     

优化能源结构 改善宣城市大气环境质量

通过对宣城市能源结构和大气环境质量现状的分析,提高了天然气、电能和太阳能等清洁能源在能源结构中的比例,并运用城市多源扩散模式进行浓度预测.结果表明:采取清洁能源替代措施以后,大气中的二氧化氮和二氧化硫按功能区划分均可达到相应的国家标准.