空气氧化解吸NO络合吸收产物试验研究

Fe(Ⅱ) EDTA易被氧化为对NO无吸收能力的Fe(Ⅲ)EDTA,为实现Fe(Ⅱ)EDTA的循环使用,提出了Fe(Ⅱ)EDTA络合吸收-空气氧化解吸-铁屑还原再生组合脱除NO新工艺.采用空气氧化解吸络合吸收产物Fe(Ⅱ) EDTA (NO)中NO的方法,研究了温度及压力对Fe(Ⅱ)EDTA(NO)空气氧化解吸过程的影响.结果表明,0.4 MPa、333K为较优的解吸条件.该工艺可循环脱除NO,成本低、效率高,能有效回收NO2资源.     

Effect of urea on detonation characteristics and thermal stability of ammonium nitrate

A study has examined the effect of urea on the thermal stability and detonation characteristics of ammonium nitrate (AN). The thermal decomposition temperature and surface morphology of samples were investigated by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). For further research on the thermal sensitivity and shock sensitivity of the samples, the Koenen test and UN gap test were conducted. The results indicate that urea can substantially increase the thermal stability of AN (the greatest exothermic peak is increased by more than 100 °C) and reduce the thermal sensitivity of AN. However, AN-50wt. % urea mixtures can still produce a steady detonation in the UN gap test. Urea cannot reduce the ability to propagate a detonation. Possible explanations for these results are discussed.     

黄壤表面电场作用下Cu~(2+)与Zn~(2+)的吸附/解吸动力学研究

利用静态恒流法研究了黄壤表面电场作用下Cu2+与Zn2+的吸附/解吸动力学.结果发现:考虑黄壤表面电场作用下,Cu2+和Zn2+的吸附实验呈现初期强吸附作用下的零级动力学过程和一定时间之后弱吸附作用下的一级动力学过程,与理论预期一致;在Cu2+和Zn2+的解吸实验中,只有前期出现了弱吸附作用下的一级动力学过程,实验结果与理论预期存在差别,原因在于专性吸附的Cu2+、Zn2+很难被解吸下来;在交换/吸附实验中,Cu2+的吸附速率值和平衡吸附量均大于Zn2+,且Cu2+-K+体系的表面电化学参数φ0、σ0、E0均大于Zn2+-K+体系中的对应值,证明了黄壤颗粒表面对Cu2+的吸附作用强于Zn2+;在交换/解吸实验中,Zn2+的解吸速率值和平衡解吸量均大于Cu2+,Zn2+-K+体系的表面电化学参数φ0、σ0、E0均大于Cu2+-K+体系中的对应值,证明Zn2+-K+体系中Zn2+的解吸作用比Cu2+-K+体系中的Cu2+解吸作用强.     

Mercury adsorption characteristics of HBr-modified fly ash in an entrained-flow reactor

In this study, the mercury adsorption characteristics of HBr-modified fly ash in an entrained-flow reactor were investigated through thermal decomposition methods. The results show that the mercury adsorption performance of the HBr-modified fly ash was enhanced significantly. The mercury species adsorbed by unmodified fly ash were HgCl₂, HgS and HgO. The mercury adsorbed by HBr-modified fly ash, in the entrained-flow reactor, existed in two forms, HgBr₂ and HgO, and the HBr was the dominant factor promoting oxidation of elemental mercury in the entrained-flow reactor. In the current study, the concentration of HgBr₂ and HgO in ash from the fine ash vessel was 4.6 times greater than for ash from the coarse ash vessel. The fine ash had better mercury adsorption performance than coarse ash, which is most likely due to the higher specific surface area and longer residence time.     

Effects of typical additives on the thermal stability of ammonium peroxydisulfate

Ammonium peroxydisulfate (APS), one of the most widely used inorganic peroxides in the process industries, is a thermally unstable peroxide and potent oxidizer due to the presence of peroxy bond in the molecule and is incompatible with most substances. To investigate the effect of typical additives on the thermal decomposition of APS, in this paper, diamine phosphate (DAP), monoamine phosphate (MAP), and aluminum hydroxide (AH) were selected as additives; pure APS and samples with 10 wt% and 20 wt% of additives were first tested by differential scanning calorimetry (DSC). The experiments and analysis showed that the samples with 10 wt% of additive had better thermal stability than those with 20 wt% of additive. After screening, the three groups of 10 wt% AH, 10 wt% MAP, and 20 wt% MAP additive conditions could be considered to have a better thermal stability effect on the thermal decomposition of APS. Four groups of samples were, in turn, tested by Phi-Tec II. The adiabatic results showed two discontinuous exothermic processes; 10 wt% AH promoted the weak exothermic effect in the first stage. In contrast, the three groups of additives in the main exothermic stage showed different degrees of inhibition, and the inhibiting effect was ranked as 10 wt% AH, 10 wt% MAP, and 20 wt% MAP in order. Finally, the self-accelerated decomposition temperature (SADT) was calculated under the 25 kg standard package. The adiabatic results, including SADT, were combined to render feasible recommendations for the use of additives, which provides references for the packaging and transportation of additives and their applications.     

Effects of environmental temperature on the thermal runaway of lithium-ion batteries during charging process

Lithium-ion batteries with relatively narrow operating temperature range have provoked concerns regarding the safety of LIBs. In this work, a series of experiments were conducted to explore the thermal runaway (TR) behaviors of charging batteries in a high/low temperature test chamber. The effects of charging rates (0.5 C, 1 C, 2 C, and 3 C), and ambient temperature (2 °C, 32 °C and 56 °C) are comprehensively investigated.The results indicate that the cell exhibited greater thermal hazard at the high charging rate and ambient temperature conditions. As the charging rate increased from 0.5 C to 3 C, more lithium intercalated in the anode prompt the TR triggered in advance, the TR onset temperature decreased from 297.5 °C to 264.7 °C. In addition, the charging time decreased with the elevated ambient temperature, resulting in a relatively higher TR onset temperature and lower maximum temperature, and the average TR critical time declined by 115–143 s. Finally, the TR required less heat accumulation with increasing of charging rate and ambient temperature, and the heat generation of side reaction played a substantial role that accounted for approximately 54%∼63%. These results provide an insight into the charging cell thermal runaway behaviors in complex operation environments and deliver valuable guidance for improving the safety of cell operation.     

Control of combustion-generated nitrogen oxides by selective non-catalytic reduction

Controlling nitrogen oxides (NO(x)) emissions is becoming a daunting technical challenge as increasingly strict emission limits are being imposed. The stringent regulations have prompted the innovation and characterization of NO(x) control technologies suitable for various applications. This paper presents a review on NO(x) removal techniques with particular reference to selective non-catalytic reduction (SNCR) technology. This includes initially how SNCR emerged as a technology along with a comparison with other relevant technologies. A review of various features related to selective non-catalytic gas phase injection of ammonia and ammonium salts (as reducing agent) is presented. The use of urea solution as a reducing agent and its performance in laboratory and pilot scale tests as well as large-scale applications is also discussed. Use of cyanuric acid as a potential reducing agent is also presented. The underlying reaction mechanisms have been reviewed for ammonia, urea and cyanuric acid for the explanation of various observations. Computational fluid dynamics (CFD) modeling as applied to SNCR is also presented. Subsequently the use of SNCR coupled with other in-combustion and post-combustion NO(x) control techniques is elaborated. Additionally, a two-stage NO(x) removal strategy to control un-reacted ammonia slip and to improve overall efficiency is discussed. At the end a summary is given which highlights various areas needing further research.     

铁盐浸渍强化污泥活性炭-甲醇热质传递特性

针对以市政污泥为核心的炭素前驱体开展原位铁盐浸渍磁修饰,通过响应曲面试验设计优化并制备了新型原位浸渍炭IM-WNC;以成品炭的后浸渍磁修饰炭PM-WNC为参比,考察了原位浸渍与后浸渍磁修饰过程对污泥活性炭-甲醇工质对的吸附/解吸速率、吸附等温线、吸附床传热性能、制冷量及制冷功率等方面的影响。结果表明:与后浸渍过程相比,原位铁盐浸渍有利于保持污泥炭总孔容积(0.6608cm³/g)及比表面积(1122m²/g)水平,能显著提升致密化污泥炭IM-WNC的导热系数(600kg/m³,4.586W/(m·K))、甲醇Sokoda&Suzuki平衡吸附量((528.74±15.86)mg/g)和Langmuir最大吸附量((673.99±13.52)mg/g)。升温脱附与冷却吸附循环体系内,IM-WNC致密化吸附床中心温度峰谷差值可达到69.07℃。当循环时间为76min,解吸温度为100℃时,IM-WNC吸附制冷床的制冷量和制冷功率分别达到501.43kJ/kg和799.06kJ/(kg·h),较PM-WNC分别提升了15.61%和18.69%。     

气相色谱法测定室内空气中挥发性卤代烃

建立了活性炭吸附-溶剂解吸-气相色谱测定室内空气中7种挥发性卤代烃的分析方法。样品经活性炭采样管富集后,用二硫化碳解吸,Agilent HP-1色谱柱分离,使用带有电子捕获检测器的气相色谱仪测定,以保留时间定性,外标法定量。当采样体积为10 L时,方法检出限范围是0.03~0.18 g/m3,加标回收率在72%~114%之间,相对标准偏差小于15%。结果表明,该方法可以应用于室内空气中痕量挥发性卤代烃样品的检测分析。     

Evaluation of solubility of polycyclic aromatic hydrocarbons in ethyl lactate/water versus ethanol/water mixtures for contaminated soil remediation applications

Solubility data of recalcitrant contaminants in cosolvents is essential to determine their potential applications in enhanced soil remediation. The solubilities of phenanthrene, anthracene, fluoranthene and benzo[a]pyrene in ethyl lactate/water and ethanol/water mixtures were measured using equilibrium techniques. The cosolvency powers derived from solubility data were then applied to the model developed from the solvophobic approach to predict the capability of ethyl lactate and ethanol in enhancing the desorption of contaminants from soils. Both ethyl lactate and ethanol cosolvents were shown to be able to enhance the solubilisation of the tested four polycyclic aromatic hydrocarbons by > 4 orders of magnitude above the levels obtained with water alone. However, ethyl lactate demonstrated a greater capacity to enhance PAH solubility than ethanol. The cosolvency powers of ethyl lactate/water system obtained from the end-to-end slope (σ) and the end-to-half slope (σ_0.5) of the solubilisation curve were 1.0--1.5 and 2.0--2.9 higher than ethanol/water system respectively. In line with this, ethyl lactate/water was demonstrated to enhance the desorption of contaminants from soil by 20%--37% and 18%--61% higher compared to ethanol/water system in low organic content and high organic content soils respectively, with a 2:1 (V/W) ratio of solution:soil and with cosolvent fraction as low as 0.4. With the exception of benzo[a]pyrene, the experimental desorption results agreed fairly with the predicted values, under an applied solution:soil ratio that was enough to hold the capacity of released contaminants.