HAP/UV催化降解活性艳蓝K-3R的研究

用化学沉淀法合成羟基磷灰石(HAP),并用XRD、SEM、FT-IR对其进行分析。以活性艳蓝K-3R为降解底物,研究HAP对其光催化降解性能。探讨了HAP煅烧温度、通气量、投加量、初始浓度等因素对光催化降解活性艳蓝K-3R效果的影响。研究表明化学沉淀法合成的HAP粒度均匀,HAP对活性艳蓝的吸附作用较强,30min之内即能达到吸附平衡,其对初始浓度为100mg/L的活性艳蓝的吸附率可达17.5%。适当的煅烧有利于提高HAP的催化活性,以200℃煅烧2h最佳。在投加量为4g/L,鼓气量为300L/h和pH=6的试验条件下,HAP(200℃)对初始浓度为100mg/L的活性艳蓝K-3R 3h的降解率达68%。降解反应动力学研究表明,HAP/UV光催化降解活性艳蓝K-3R的过程符合Langmuir-Hinshel-wood一级动力学方程,降解速率常数k随着活性艳蓝K-3R浓度的增大而减小。     

使用量和单位常见错误浅析

以《量和单位》(GB3100-3102-1993)为依据,列举了各种常见的错误使用量和单位的名称和符号、量和单位非标准化的例子,对其进行了分析和探讨,提出标准化对策。     

挥发性有机物泄漏检测与修复技术规范体系的设想研究

泄漏检测与修复技术对于控制工业企业无组织挥发性有机物排放效益明显,通过分析泄漏检测与修复技术的国内外发展状况,结合该技术在实际操作中的相关要求,提出建立和完善包括工业企业泄漏元件编码原则、泄漏检测与修复操作技术规范、泄漏检测与修复核查与评估方法、LDAR技术泄漏量核算方法以及LDAR技术信息管理系统接口规范在内的挥发性有机物泄漏检测与修复技术环境管理规范体系的整体设想,以促进挥发性有机物总量减排和环境空气质量改善.     

Thermal hazard assessment for synthesis of 3-methylpyridine-N-oxide

The exothermic oxidation of 3-methylpyridine with hydrogen peroxide was analyzed by Reaction Calorimeter (RC1e) in semi-batch operation. Heat releasing rate and heat conversion were studied at different operating conditions, such as reaction temperature, feeding rate, the amount of catalyst and so on. The thermal hazard assessment of the oxidation was derived from the calorimetric data, such as adiabatic temperature rise (ΔT_ad) and the maximum temperature of synthesis reaction (MTSR) in out of control conditions. Along with thermal decomposition of the product, the possibility of secondary decomposition under runaway conditions was analyzed by time to maximum rate (TMR_ad). Also, risk matrix was used to assess the risk of the reaction. Results indicated that with the increase of the reaction temperature, the reaction heat release rate increased, while reaction time and exotherm decreased. With the increase of feeding time, heat releasing rate decreased, but reaction time and exotherm increased. With the amount of the catalyst increased, heat releasing rate increased, reaction time decreased and exothermic heat increased. The risk matrix showed that when the reaction temperature was 70 °C, feeding time was 1 h, and the amount of catalyst was 10 g and 15 g, respectively, the reaction risk was high and must be reduced.     

Reaction mechanism and process safety assessment of acid-catalyzed synthesis of tert-butyl peracetate

Esterification during the synthesis of tert-butyl peracetate (TBPA) is highly exothermic. Since peroxides (tert-butyl hydroperoxide TBHP and TBPA) are intrinsically thermosensitive, this synthesis process is potentially dangerous. In this work, the exothermic process and mechanism of TBPA synthesis using acetic anhydride (Ac₂O) and TBHP under the catalysis of sulphuric acid (H₂SO₄) were clarified by calorimetry, infrared spectroscopy, and high-performance liquid chromatography. To substantially alleviate the thermal risk of the reaction, and to feasibly select appropriate synthesis conditions for ensuring the process safety of the synthesized products, several sets of isothermal and isoperibol experiments were performed using calorimetry. The intermediates formed and concentration changes during the reaction were monitored using in-situ Fourier-transform infrared spectroscopy. Differential scanning calorimetry and adiabatic calorimetry were used to assess the thermal hazard of the materials during the synthesis process. The reaction mechanism was verified using density functional theory calculations. The results revealed that a controlled increase in exothermicity could be achieved by adding aqueous TBHP to Ac₂O in semi-batch experiments in isothermal mode, and accordingly, the highest yield was 95.71%. Experiments combined with theoretical calculations revealed that the primary exothermic event was the TBPA formation reaction, and the removal of a large amount of water from TBHP prior to this is favourable for the reaction. The criticality classes of this reaction were of Grade 2.     

Process hazard assessment of energetic ionic liquid with kinetic evaluation and thermal equilibrium

With the continuous development of battery technology, there are new research investments in materials of various parts. In the field of electrolytes, ionic liquids (IL) are considered to be excellent electrolytes and have been widely studied in distinct energy fields. However, it is necessary to pay attention to the safety characteristics of ionic liquids at high temperature due to the application of energy, but there is little research on the reaction and kinetics of ionic liquids. To ensure the safety of ionic liquids, such as high temperature, the common ionic liquid 1-Ethyl-3-methylimidazolium nitrate ([Emim] NO₃) was selected for analysis. The exothermic mode is obtained from the data of differential scanning calorimetry. The basic reaction parameters of [Emim] NO₃ were determined with thermodynamic equation simulation. For ionic liquids in the actual situation, consider adding a heat balance model to estimate its temperature change pattern and find out the hazard temperature and related safety parameters. Temperature changes were estimated by constructing 25.0 g and 50.0 g packages to simulate material reactions and heat transfer in the external environment. The results showed that [Emim] NO₃ had shorter TMR_ad and TCL (<1 day) when the temperature was above 180 °C.     

催化湿式氧化处理H-酸溶液的反应动力学

两阶段一级反应动力学模型和广义动力学模型被用来描述湿式氧化 ( WAO)及催化湿式氧化 ( CWAO)反应过程 ,并确定了动力学参数 .2个模型的计算值均与实验值相符 ,而广义动力学模型相对更准确些 .2个模型均表明反应分 2个步骤 :首先是H-酸被迅速氧化成小分子有机酸 ,后者再缓慢氧化 .这 2个步骤由模型参数加以表征 ,因而模型可被用来对 CWAO催化剂进行评价 .     

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.     

Are network indices robust indicators of food web functioning? A Monte Carlo approach

Indices based on network theory are often used to describe food web functioning. These indices take as input food web flows that are estimated based on merging of (scarce) data with linear inverse methods (LIMs). Due to under sampling, most food webs are highly uncertain and can only be quantified within a specific uncertainty range. The linear inverse method (LIM) can estimate food web flows using a variety of techniques, e.g. the parsimonious or minimum norm (MN) solution, which selects one food web, based on a quadratic minimization technique or the Monte Carlo solution where a finitely many random solutions are generated which are then averaged. We use the Monte Carlo approach (MCA) to estimate the values of several indices from four published food webs, the Gulf of Riga for the autumn, summer and spring seasons, and the Takapoto atoll system. We first show that network indices are much better constrained than the uncertain food webs from which they are calculated. Therefore, even in the face of food web uncertainty, they are robust estimators of food web functioning. We then use the MCA-derived network indices to generate cumulative density functions for each index. These serve to compute the probabilities of the MN indices estimates being an extreme solution as compared to the median values. Our findings show that 82% of the MN solutions are smaller than the MCA solutions, and 63% of the network indices are significantly under-estimated.     

应用遗传算法优化氢气/空气燃烧反应系数

研究目的是优化氢气/空气简化反应机理的系数,使得简化机理在一定的误差范围内,能代替详细机理.通过计算氢气/空气详细反应机理得到的组分浓度作为遗传算法的适应度目标,对简化机理进行优化.结果显示,优化后的简化机理不仅在在计算组分浓度,而且在层流预混火焰速度和组分时空分布方面,更加接近详细机理所能达到的计算结果,比优化之前的简化反应机理计算结果更加准确.