定容-氧气循环燃烧法测定捕收剂的吸附量

研究了一种定容-氧气循环燃烧法测定捕收剂吸附量的方法,并与传统的溶剂萃取-分光光度法进行了比较。实验表明,定容-氧气循环燃烧法较溶剂萃取-分光光度法测定油酸钠在磷矿石表面的吸附量更简便、准确。     

聚氨酯泡沫塑料中氯的测定

研究了氧瓶燃烧-分光光度法测定聚氨酯泡沫塑料中氯含量的方法．采用氧瓶燃烧法分解聚氨酯泡沫塑料,然后用硫氰酸汞分光光度法测定其中氯含量．实验结果表明,氧瓶燃烧-分光光度法能有效地测定聚氨醣泡沫塑料中氯元索的含量,该方法简便、准确、实用性强、灵敏度高,适合快速分析。     

萃取分光光度法测定天然水中铀

为了测定天然水中铀,通常是首先分离铀,分离铀的方法有共沉淀,离子交换,活性炭吸附等;溶剂萃取具有简便快速的优点,然而,大部分溶剂萃取的方法往往缺乏必要的重现性和选择性,因此需复杂的计算或进一步纯化样品的步骤。有些萃取分光光度法测铀灵敏度比较低,不适合天然水中铀的测定。     

粉煤灰磁性吸附剂的制备及磷吸附机理

通过化学沉淀法制备了CMS@La_2O_3磁性磷吸附剂。结构及磁性表征显示,氧化镧较均匀的包覆在粉煤灰磁珠表面;样品的比磁化强度达20.35 emu·g~(-1),可实现高效磁分离。利用钼酸铵分光光度法对所得磁性吸附剂的磷吸附性能进行了试验研究。研究表明,其最高磷比饱和吸附量可达19.50 mg·g~(-1),吸附时间、pH值、共存阴离子等因素对磷吸附效果均具有显著影响。吸附动力学拟合表明,CMS@La_2O_3对含磷离子的吸附符合准二级动力学方程,以化学吸附为主,磁性吸附剂对含磷离子的吸附反应过程可由La_2O_3表面羟基化-离子交换模型解释。吸附磷后的CMS@La_2O_3吸附剂经处理后可多次循环使用。     

原子吸收分光光度法分别测定水中的三价铬和六价铬

铬的价态不同,其毒性也不一样,因而在环境水质监测中,不仅要测定铬化合物的总含量,同时也要分别测定各种价态铬化合物的含量。溶剂萃取是采用原子吸收分光光度法最常用的预处理方法。但是它的选择性和重复性都不够好,尤其是在有机溶剂雾化燃烧时,产生刺激性的烟气,影响工作。本工作采用在酸性条件下,将水样通过D_(301)大孔阴离子交换树脂柱,六价铬被交换吸附,而和三价铬分离。再用还原性反洗液使柱上的六价铬还原溶出,并得到富集。而后,用原子吸收分光光度法直接测定流出液中的三价铬和反洗溶出液中由六价转变为三价的铬。     

环境样品中硝基苯类化合物的分析方法研究进展

主要介绍了我国近年来在环境样品中硝基苯类化合物的分析研究进展,内容包括:光度法(还原-偶氮光度法、阻抑动力学光度法、化学计量学分光光度法、人工神经网络-分光光度法)、气相色谱法(固相微萃取-毛细管气相色谱法、树脂吸附-气相色谱法、液-液微萃取气相色谱法、超声萃取-气相色谱法)、高效液相色谱法(反相高效液相色谱法、固相萃取-高效液相色谱法)和极谱法等分析方法。     

萃取富集-三波长紫外分光光度法测定天然水中微量酚

酚类化合物对生物体有害,我国环保部门规定地面水中酚类化合物最高允许量为10ppb。因此寻求一种快速准确的测定天然水或废水中微量酚的方法很有必要。沿用的4-氨基安替比林法,紫外分光光度法各有缺点。Afghan总结了各种富集方法后,认为溶剂萃取富集最方便和准确,并提出了用醋酸正丁酯作萃取剂。     

牛血清白蛋白在NVP/HEMA无规共聚物水凝胶上的吸附研究

合成了不同含水量的N-乙烯吡咯烷酮(NVP)／甲基丙烯酸-β-羟乙酯(HEMA)共聚物水凝胶．研究了温度、pH值，蛋白质初浓度及离子强度等因素对牛血清白蛋白吸附性能的影响．采用紫外分光光度法测定BSA的吸附量．结果表明，蛋白质初浓度越高．温度越高，离子强度越大；蛋白质内部更多的疏水性氧基酸残基暴露于外部．吸附量增加：在等电点pH=4．7附近蛋白质沉积量最大．     

快速溶剂萃取-红外分光光度法测定低含量油污染土壤中总石油烃的含量

研究快速溶剂萃取对低含量油污染土壤中总石油烃的萃取效果,并与索氏提取、超声萃取、微波萃取进行比较。制备了模拟污染样品,并以单因素和正交试验优化快速溶剂萃取条件,红外分光光度法测定石油烃含量。结果表明快速溶剂萃取低含量油污染土壤中总石油烃的最佳条件为:压力为1.03×10~7Pa时,萃取15min,萃取温度100℃,循环4次,氮气吹扫45s,萃取剂为丙酮-二氯甲烷(1+1)混合液。按上述方法对不同污灌年限的土壤进行总石油烃含量测定,得到新疆某污灌区土壤中石油烃的质量分数为211.05~389.50mg·kg~(-1),测定值的相对标准偏差(n=5)为2.3%~6.4%。     

高价小分子型分散剂在Al2O3表面的吸附研究

采用5-硝基水杨酸合铁()分光光度法测定了2-膦酸丁烷-1,2,4-三羧酸(PBTCA)及柠檬酸在Al₂O₃表面的等温吸附线,发现二者的饱和吸附量均随pH值的升高而减小,且PBTCA比柠檬酸的饱和吸附量高.ζ电位及沉降实验亦表明,与柠檬酸相比,PBTCA的吸附使Al₂O₃表面的有效负电荷量更高,且其分散作用也更佳.采用FTIR及AES研究了PBTCA在Al₂O₃表面的吸附机理.膦酸基的存在提高了PBTCA在碱性条件下的吸附能力.     

Contribution to the technology of disposal of the liquid organic radioactive wastes

Some problems of the radioactive dowtherm disposal in the nuclear power plant Al by a method of fluid combustion are outlined. An experimental combustion station as well as its specifications are described.     

Influence of Nanoseconds Pulsed Discharges on the Composition of Intermediate and Final Combustion Products in the HCCI Engine

Plasma Chemistry and Plasma Processing - The composition of combustion products depending on the method for the organisation of combustion in the HCCI engine (with and without a non-equilibrium...     

Evaluation of the sealed‐tube low‐temperature combustion method for the 13C/12C and 2H/1H ratio determinations of cellulose nitrate

Traditionally‐suggested combustion time of 1 h at 550°C) with the sealed‐tube combustion method for determining the ¹³C/ ¹²C ratio of cellulose nitrate or other nitrogen‐containing components could produce large negative deviation up to 1°. Three types of cellulose are used to ascertain possible causes. The presence of nitrous oxide (N₂O) formed during combustion is most likely responsible for this deviation. Prolongation of the combustion time (at least 5 h at 550°C) and intimate contact between copper oxide and organic matter can greatly improve the analysis precision and effectively reduce this deviation to an acceptable level. Regardless of scattered carbon isotope data, hydrogen isotope data are all reproducible within 2° when this method is coupled with the high temperature uranium reduction method. Thus, care should be taken for determining carbon and nitrogen isotope compositions of nitrogen‐containing substances using the low temperature sealed‐tube combustion method.     

制革、造纸和湖泊污泥燃烧特性的研究

利用热重分析法对城市湖泊污泥、制革污泥,以及两种造纸污泥进行了实验研究,并分析了污泥的燃烧特性。结果表明,四种污泥都具有高挥发分、高灰分、低热值的特点。污泥的燃烧分为挥发分燃烧和固定碳燃烧两个阶段,除了制革污泥在两个阶段失重份额相当外,湖泊污泥和造纸污泥的挥发分燃烧阶段失重都超过燃烧总失重的70%,表明挥发分是污泥中的主要可燃成分,而且挥发分和燃烧过程温度范围比较宽。污泥的挥发分燃烧DTG峰有明显的多峰叠加现象,表明污泥的挥发分析出组分较为复杂。运用Coats-Redfern积分法进行动力学分析后表明,大部分污泥的燃烧过程为二级反应,污泥燃烧的活化能较低。     

On the Structure of the Spectra for a Class of Combustion Waves

The stability of a premixed laminar flame supported by a general combustion reaction system is considered using the Evans function method. The spectrum of the linearised second-order differential operator is investigated in detail. The special structure of the differential equations due to an Arrhenius temperature dependence is exploited. It is shown that, for certain combustion systems, the limit of the Jacobian of the reaction terms as the travelling wave coordinate approaches the front and rear of the flame is a lower triangular matrix. For this type of system a simple geometrical method is shown for the study of the essential spectrum of the linearised operator, and for determining the domain of the Evans function. The results are applied to some representative combustion reactions.     

CSP分析方法在简化燃烧化学反应系统中的应用

基于计算奇异摄动(CSP)思想, 对甲烷/空气预混燃烧系统进行分析. CSP将反应空间分裂, 消除刚性; 将单点分析和全局分析相结合, 合理选择主要组分和稳态物质, 使用CSP的特征指数简化方程. 构建了针对甲烷/空气预混燃烧系统的总包15步反应机理, 并利用Sandia实验室的PREMIX软件包对该系统进行分析, 验证了简化机理的准确性, 证实了CSP分析方法在燃烧系统中应用的可靠性和优越性, 并为研究简化燃烧系统的分析提供了一种新的思路.     

Study of the combustion mechanism of oil shale semicoke in a thermogravimetric analyzer

Oil shale semicoke, formed in retort furnaces, is a source of severe environmental pollution and is classified as a dangerous solid waste. For the industrial application of oil shale semicoke in combustion, this present work focused on the thermal analysis of its combustion characteristics. The pyrolysis and combustion experiments of semicoke were conducted in a Pyris thermogravimetric analyzer. From the comparison of pyrolysis curves with combustion curves, the ignition mechanism of semicoke samples prepared at different carbonization temperatures was deduced, and was found to be homogeneous for semicoke samples obtained at lower carbonization temperature, shifting to heterogeneous with an increase in the carbonization temperature. The effect of carbonization temperatures and heating rates on the combustion process was studied as well. At last, combustion kinetic parameters of semicoke were calculated with the binary linear regression method, showing that activation energy will increase with increasing the heating rate.     

The determination of the nitrogen content and nitrogen-15 abundance by means of the nitrogen gas generated from inorganic and organic materials

A method is described for the determination of the total nitrogen content, after conversion to nitrogen gas, of various types of samples before the mass-spectrometric analysis of the ¹⁵N abundance. The sample is burned with a mixture of copper oxide, copper and lime in a closed tube under vacuum (modified Dumas method). The gas is released into an evacuated chamber of known volume and the nitrogen pressure is used to determine the nitrogen content of the sample. The gas is then admitted into a mass spectrometer. In order to obtain complete combustion of the material and to generate pure nitrogen gas, various combustion temperatures, combustion times and oxidizing agents were compared.     

Effect of Preparation Method on the Structural Characteristics of NiO-ZrO2 Oxygen Carriers for Chemical-looping Combustion

Chemical-looping combustion(CLC) offers an effective approach for power generation and CO₂ capture. In this work, an NiO-ZrO₂ oxygen carrier prepared by three methods was subjected to an optimal reaction temperature test, an optimal flow test and a cyclic redox reaction test to explore the most suitable reaction conditions. Through comparative analysis, it is noted that the coprecipitation method is not suitable for the preparation of this NiO-ZrO₂ oxygen carrier, while the oxygen carrier prepared by the mechanical mixing method and solution combustion method obtained a higher CH₄ conversion rate and CO₂ selectivity. In addition, these two oxygen carriers also showed high stability during successive CLC testing. Therefore, both the mechanical mixing method and the solution combustion method can be used to prepare NiO-ZrO₂ oxygen carriers.     

两相流中煤粉的燃烧机理及动力学特征

利用微型流化床动力学分析仪研究了两相流条件下无烟煤粉的燃烧反应机理和动力学特征,并与热重法所得结果进行比较分析。结果表明,当温度大于850℃时,煤粉燃烧机理发生了变化,燃烧气态产物的生成比例也随之改变;当气速大于0.10 m/s时,气体扩散限制基本被消除,煤粉燃烧反应速率主要受界面化学反应控制;煤粉燃烧反应速率随着氧气分压的增大呈幂函数形式增长,且氧气分压对煤粉静置燃烧的影响更加显著。煤氧两相流燃烧的表观活化能与静置燃烧相比降低了49 kJ/mol,相同温度条件下两相流燃烧的界面化学反应阻力也明显小于热重法测试结果。