储能硝酸熔盐的热稳定性分析

研究了商业化储能二元混合硝酸熔盐Solar salt (60% NaNO3?40% KNO3)的热稳定性和恒温热稳定性,采用热重法分析了其热分解温度,通过恒温实验考察了处于开放空气气氛中的NaNO3, KNO3和Solar salt在不同温度下的热稳定性,研究了NaNO3和KNO3在Solar salt高温不稳定性中的作用. 结果表明,大于500℃时温度越高,熔盐越不稳定,相同温度下不稳定程度NaNO3>Solar salt>KNO3. 温度升高,分解产物NO2?平衡含量增大而达到平衡的时间缩短,O2?含量很低. Solar salt中硝酸盐热分解和挥发的质量损失比接近1:1,NaNO3是造成体系热分解的主要原因,而KNO3起到抗挥发的作用.     

Preparation of nanocrystalline nickel oxide from nickel hydroxide using spark plasma sintering and inverse Hall-Petch related densification

Nanocrystalline nickel oxide (NiO) was prepared from nickel hydroxide by Spark plasma sintering (SPS) and the mechanisms involved in the densification of NiO were studied. Reverse precipitated nickel hydroxide powders were SPS processed at 400, 600 and 700?°C with 70?MPa pressure. Pure NiO with 12?nm crystallite size formed after 400?°C sintering process. However NiO grains had grown to 18 and 38?nm after 600 and 700?°C sintering respectively. NiO pellets prepared using 600 and 700?°C SPS sintering schedules had relative densities of 83% and 94% respectively. Two displacement rate regimes were observed during densification of NiO in both 600 and 700?°C sintering processes. Decomposition of nickel hydroxide and particle sliding of NiO led to first displacement rate maximum while inverse Hall-Petch based plastic deformation facilitated densification during the constant second displacement rate regime. No densification occurred during sintering holding times indicating the limited role that diffusion played during densification.     

Oxygen vacancy levels on gadolinia-doped ceria interlayer deposited by atmospheric pressure plasma jet for solid oxide fuel cells

The oxygen vacancy levels as a factor on different gadolinia-doped ceria interlayer (GDCi) films deposited on yttria stabilized zirconia (YSZ) electrolyte substrates by an atmospheric pressure plasma jet (APPJ) via precursor solution of nitrate salts are investigated. Focusing on the effect of carrier gases, scanning electron microscopy (SEM), Raman, and X-ray diffraction (XRD) are implemented for the materials characterization of the as-deposited GDCi films and sintered-GDCi films at various temperatures. The higher level of oxygen vacancies in GDCi films adhered on 8YSZ electrolyte are evidently analyzed using Ar as the carrier gas during the deposition, of which the interdiffusion resulted in the formation of (GDC + YSZ) solid solution for sintering over 1300?°C degraded the total conductivity. The deposition of GDCi films on 8YSZ by APPJ method using O₂ carrier gas significantly improved the total conductivities of the whole electrolyte layers. Moreover, this study provides the useful insight into the oxygen vacancy levels on GDC films as interlayer (GDCi) to improve the values of open circuit voltage in LSM/GDCi/YSZ/Pt full-cell, as well as offering the efficiency of APPJ as one step deposition process.     

A novel method of unburned hydrocarbons and NOx gases capture from vehicular exhaust using natural biosorbent

Automobile emissions are composed of NO_x and unburned hydrocarbon that contribute significantly to major environmental and health issues. In this study, encapsulated Moringa oleifera beads (EMBs) were synthesized using Moringa oleifera pod powder that was cross-linked with calcium alginate and used as a biosorbent for reducing the emission gas concentrations from the single-cylinder diesel engine. The breakthrough curve was attained from single and double stage of fixed bed column by the influence of temperature ranging from (80°C–120°C) ± 5°C with a feed flow rate varying from 8 to 10 kg hr^–1 and bed height varying from 15 to 30 cm. Based on the experimental results, the maximum biosorption capacity (q_o) was found to be 14.45 and 123.51 mg g^–1 for HC and NO_x, respectively, and was obtained at 80°C–90°C with double stage of BH–30cm under flow rate of 8 kg hr^–1. Further, breakthrough curves were investigated, and the experimental data were fitted using well-established models like Thomas, Yoon–Nelson, and Wang models. In addition, mass transfer models like Weber–Morris and Boyd were investigated to identify the rate-limiting step of the overall biosorption process.     

液质联用技术在化妆品禁用组分测定中的应用

介绍了液质联用分析中的关键技术包括样品前处理技术、常用的质量分析器、基质效应消除方式、定性定量测定等,综述了液质联用技术在化妆品禁用组分测定中的应用,指出目前化妆品中禁用物质的组分检测已从单一成分向多组分发展,更多简单的样品前处理技术,高通量、高分辨率、高准确度的质量分析技术已应用于化妆品禁用组分的检测。     

采用多相放电反应技术加氢精制生物油的试验研究

针对目前生物油加氢技术中存在的催化剂易结焦、工艺过程不能连续等问题,采用多相放电反应对生物油进行加氢精制。构建了生物油/固体催化剂/H₂的多相放电体系,研究了催化剂类型、工作电压、气体流量、反应时间等条件对精制生物油的加氢脱氧效果的影响。研究结果表明：随着工作电压和气体流量的增大,多相放电催化加氢精制生物油的脱氧率（R）呈现出先增加后减少的趋势;随着反应时间的延长,呈现出先增加后稳定的趋势。在工作电压为22kV,气体流量为60mL/min,反应时间为120min的工艺条件下,脱氧率最高可达41%。与生物原油相比,多相放电催化加氢精制的生物油中醇类、酚类、酮类等物质的含量相对较低,而碳氢类物质显著增多。     

煤粉质量流量计的选择与应用

介绍了煤粉固体质量流量测量技术及产品,总结了固体质量流量计在粉煤气力输送过程中的应用情况,探讨了电容式固体流量计工业规模下试验标定方法和结果,对于气固两相流工业在线测量提供了参考。     

顶空气-质联用法测定离子液体富集的空气中的苯系物

基于室温离子液体无蒸气压、离子强度高且稳定、优良溶解性等特点,实验中采用室温离子液体［bmim］［PF₆］作为吸收液,气相色谱-质谱联用分析测定离子液体富集的苯系物,建立了顶空进样-气相色谱-质谱方法测定苯、甲苯、间二甲苯、邻二甲苯、苯乙烯的最佳分析条件。结果表明离子液体有可能作为空气中苯系物的富集材料。     

Mass transfer and separation criteria for high‐speed countercurrent chromatography

High‐speed countercurrent chromatography (HSCCC) is a versatile technique for preparative separations of a wide variety of solutes. For optimization of operating conditions, prediction of separations, and scale‐up study, a model is needed to describe the effluent concentration profile, which determines the separation efficiency (mass transfer, mixing, and partitioning) and the resolution between peaks. A transfer‐dispersive model is proposed to describe the effluent profile based on the assumption that the retention of a peak is caused by partitioning over two phases, and peak broadening is caused by axial dispersion and mass transfer limitation. In this work, mass transfer was investigated by comparing model simulations to experimental data. One generalized correlation of overall mass transfer coefficients was derived. Based on the correlations of axial dispersion coefficients in our previous work and mass transfer coefficients in this study, the model predicts the elution concentration profile well. Furthermore, separation criteria were proposed to predict the separation of two adjacent solutes, and they were verified using literature data. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

Control and enhancement of permselectivity of membrane‐based microcapsules for favorable biomolecular transport and immunoisolation

The success of membrane‐based, cell‐encapsulating microcapsules depends on the membrane permselectivity that provides efficient inward transport of nutrients, therapeutic protein egress, and complete exclusion of immunoglobulins. Microcapsules with a calcium crosslinked alginate core and a genipin‐crosslinked chitosan alginate (GCA) were prepared with good control over size, membrane thickness and density. Importantly, in this study, we report a novel approach of using three relevant biomolecules and investigating the effects of the membrane characteristics (thickness and density) and microcapsule size on biomolecular mass transport across the GCA microcapsules using mathematical models based on a balance of the chemical potential. Scaling analysis was used to interrelate the membrane thickness, chitosan–alginate reaction rate constant, and diffusion coefficient. The resistance to diffusion of the three biomolecules increased with membrane density and thickness. Interestingly, swelling in the large microcapsules resulted in an increase in permeability, allowing larger biomolecules (immunoglobulin and carbonic anhydrase) to diffuse more readily. In the case of the smaller biomolecule, vitamin B₁₂, a shorter diffusion path length in smaller microcapsules allowed better ingress. When compared with other microcapsules, the GCA microcapsules possess improved permselectivity for them to allow diffusion of small nutrient molecules and proteins, whereas completely excluding antibodies. Also, these results elucidate the importance of membrane properties and microcapsule size to realize favorable transport of biomolecules. © 2011 American Institute of Chemical Engineers AIChE J, 2011