Reaction hazard and mechanism study of H2O2 oxidation of 2-butanol to methyl ethyl ketone using DSC,Phi-TEC II and GC-MS

Methyl ethyl ketone (MEK) oxidation via H₂O₂ with tungsten-based polyoxometalate catalysts has gained much attention with an ever-growing body of knowledge focusing on the development of environmentally benign processes in chemical industry. In this study, two calorimetry techniques, differential scanning calorimetry (DSC) and Phi-TEC II adiabatic calorimetry, were employed to analyze the thermal hazards associated with the 2-butanol oxidation reaction system. Hydrogen peroxide was the oxidant and a tungsten-based polyoxometalate as the catalyst. Gas chromatography-mass spectrometry was used for identification of the organic products. Important thermal kinetic data were obtained including “onset” temperature, heat of reaction, adiabatic temperature rise and self-heat rate. From DSC results, three exothermic peaks were detected with a total heat generation of approximately 1.26 kJ/g sufficiently to induce a thermal runaway. Possible reaction pathway for three stages were proposed based on both DSC and GC-MS results. One exotherm was detected by Phi-TEC II calorimeter and the pressure versus temperature profile together with the DSC and GC-MS data demonstrate the complexity of 2-butanol reaction system under both thermal screening and adiabatic conditions.     

北方县城生活垃圾填埋场的探讨

本文对垃圾填埋场垃圾处理工艺进行阐述,详细描述垃圾填埋场建设内容,并对垃圾填埋场建设的必要性进行分析。     

特殊环境中气载放射性物质的监测研究

本文对特殊环境下气载放射性物质中β放射性气体以及β放射性气溶胶做以实验,并根据后期的实验结果进行分析,详细探讨两者的测量结果,希望能为相关人士提供有效参考。     

基于二氧化钛纳米管有序阵列的氢气探测

基于气体传感器对H_2的泄漏进行探测监控,可以有效预防和控制H_2火灾爆炸事故的发生。通过阳极氧化法制备了高度有序的二氧化钛(TiO_2)纳米管阵列并制成气体传感器元器件,研究其在空气气氛中对H_2的气敏特性。通过粉末X射线衍射(XRD)、扫描电子显微镜(SEM),透射电子显微镜(TEM)表征手段研究了TiO_2纳米管的相组成和微观结构。TiO_2纳米管具有优异的气敏性能,可在200℃以上对H_2进行有效探测,检测极限达到20ppm。325℃对1 000ppm H_2灵敏度为446,响应时间为2s,对H_2选择性好。     

Assessing Aerobic Biodegradability of Plastics in Aqueous Environment by GC-Analyzing Composition of Equilibrium Gaseous Phase

Testing biodegradability of plastics under varied conditions of the environment as well as under laboratory conditions in accordance with valid international standards is very laborious, lengthy and often also economically demanding. For this reason, applicability was verified of gas chromatography to analyze gaseous phase when investigating the biodegradation course of plastics in an aqueous environment as an alternative to customary employed methods. A mathematical model of acid–basic CO₂ equilibrium in a gas–liquid system was worked out, enabling to determine quantity of produced CO₂ through chromatographic analysis of gaseous phase, in dependence on ratio of liquid and gas phase volumes (V _l/V _g) and on actual pH of liquid phase. Experimental conditions for organizing the tests were optimized. A ratio that proved suitable was V _l/V _g ≅ 0.1 at pH ≈ 7.1 of liquid phase. Under these test conditions, biodegradability of model samples, PHB, Gellan gum and Xanthan gum, was explored; course of biodegradation was studied through produced CO₂ (values ) determined by analyzing gaseous phase through gas chromatography on the one hand, and through customary “titration” procedure on the other. With water-soluble polymers, the decrement in dissolved organic carbon (values D _DOC) was also studied. Difference between values does not exceed 5%. The procedures in question are alternative “substituting” procedures for observing course of aerobic biodegradation of substances in an aqueous environment.     

毛细管柱气相色谱法同时测定水中甲醇、乙醇和N,N-二甲基甲酰胺

采用HP-PLOT Q毛细管柱,气相色谱氢火焰离子化检测器同时测定地表水和废水中甲醇,乙醇,N,N-二甲基甲酰胺,方法不受水中苯系物的干扰,在甲醇,乙醇,N,N-二甲基甲酰胺分别为7.92~792 mg/L,7.98~798 mg/L和9.45~945 mg/L范围内线性良好,相关系数均0.999,准确度高,加标回收率均94.2%,精密度好,相对标准偏差均≤5.79%,检出限分别为1.17,1.31和2.05 mg/L。     

GC-MS/MS法测定石油污染土壤中的多环芳烃

采用丙酮-正己烷混合溶液(体积比为1∶1)提取石油污染土壤样品中10种典型多环芳烃,用GC-MS/MS法测定。通过优化前处理和测定条件,使方法在0.100 mg/L～10.0 mg/L范围内线性良好,方法检出限为5.00μg/kg～15.8μg/kg。土壤样品加标回收试验6次测定结果的RSD为0.1%～16.6%,加标回收率为43.1%～109%。将该方法用于测定湖南某石化项目周边的实际土壤,结果表明该地区不同点位土壤中多环芳烃测定值为未检出～300μg/kg,在国家标准规定的范围内。     

气相色谱法测定空气中三氯乙烯和四氯乙烯

应用气相色谱法以５％ＰＥＧ－６０００为固定液、６２０１为担体填充柱分离,电子捕获检测器检测,直接进样测定环境空气中三氯乙烯和四氯乙烯。对０．０２９ｍｇ／ｍ＾３四氯乙烯标准样作重复５次测定,其相对标准差分别为５．７％和１．５％,并在实际样品中进行加标回收试验,回收率三氯乙烯在９０％～１１０％、四氯乙烯在９４％～１０８％之间。检测限分别为０．００６ｍｇ／ｍ＾３和０．０００５ｍｇ／ｍ＾３,完全能满足环境     

气相色谱法测定环境空气中1,2-环氧丙烷

以活性炭吸附环境空气中 1,2 -环氧丙烷 ,用二硫化碳洗脱 ,OV - 10 1:30m× 0 32mm× 0 2 5 μm毛细管柱低温分流进样分离 ,氢火焰离子化检测器测定 ,保留时间定性 ,峰高定量 ,采样吸附率达 99%。方法有较宽的线性范围 ,较高的灵敏度和精密度。当采样体积为 30L时 ,1,2 -环氧丙烷的检测限为 0 0 0 5mg/m3     

动态顶空气相色谱法测定水中极性水溶性有机物

采用动态顶空气相色谱FID法测定水中乙醛、丙酮、甲醇、丙烯醛、丙烯腈、乙腈、吡啶等7种极性水溶性有机物,通过优化动态顶空条件,使该方法在0．157mg／L～7．92mg!L之间线性良好。方法检出限在0．008mg／L～0．048mg／L之间,空白水样的加标回收率为103％～111％,RSD为5．4％～8．7％。用该方法测定某制药企业排口污水和地表水,只有污水中甲醇、乙腈、吡啶有响应值。