Separation of water-in-oil emulsion with microfiber glass coalescing bed

Water-in-oil emulsion separation through a fibrous media bed is a complex and challenging process in industries. In this article, we used a vertical column separator to investigate the effects of the height and porosity of the fiber bed, the structure arrangement (the mixed or the layered fibrous bed), the superficial velocity of the water-in-oil emulsion through the bed, and the influent water content of the emulsion on water removal. Four kinds of glass microfibers (GF1-GF4) with mean diameters of 0.6, 2.6, 4.6, and 8.0?µm, respectively, acted as the coalescence medium and composed the fibrous bed with different structure types. The separation efficiency could reach 97.1% with a relatively low pressure drop under the optimal bed structure and operational conditions. It also showed that the mixed bed had higher separation performance compared to the layered fibrous bed.     

Influence of alkyl chain length of alpha olefin sulfonates on surface and interfacial properties

Alpha olefin sulfonates (AOS) with various alkyl chain lengths have been used to investigate the influence of alkyl chain length on the interfacial properties at air–water, liquid paraffin–water, and parafilm–water interfaces. It was found that the critical micelle concentration decreased with increasing alkyl chain length, while the efficiency of reducing surface tension was inverse relationship with alkyl chain length. The diffusion coefficient obviously reduced with an increase of surfactant concentration and alkyl chain length. The C_14-16AOS shows better wettability and emulsification than C_16-18AOS and C_20-24AOS. For foaming properties, the foamability and foam stability dramatically decreased with increasing alkyl chain length.     

ZnCl_2溶液中微波辅助SnCl_4催化纤维素制备5-HMF

将纤维素溶解在ZnCl_2溶液中,以SnCl_4为催化剂,微波下使纤维素降解成5-羟甲基糠醛(5-HMF)。实验考察了微波功率、纤维素的质量、ZnCl_2溶液浓度、反应时间及催化剂与纤维素物质的量比等对5-HMF产率的影响。结果表明,以SnCl_4为催化剂,在优化条件:1.0 g纤维素溶解在100 m L 70%ZnCl_2溶液中,微波功率为420 W,降解反应9 min,SnCl_4与纤维素物质的量比2∶1下,5-HMF的产率达到39.4%。     

Mg/Al物质的量比对Ce-La/MgAl2O4-x催化剂催化CO还原NO性能的影响

采用初始浸渍法制备了不同Mg/Al物质的量比的Ce-La/MgAl₂O₄-x催化剂,并通过低温N₂-吸附脱附、XRD、H₂-TPR和CO-TPR等手段对其进行了表征。结果表明,在Mg/Al物质的量比为0.5时,催化剂催化CO还原NO的性能最好。这主要是因为适量Mg的添加促进了CeO₂的分散和Ce-O-La固溶体的形成,从而使得表面Ce³⁺和氧空穴增加。两者的协同作用使得Ce-La/MgAl₂O₄-0.5表现出最佳的催化性能。另外,适量Mg的引入可以抑制Ce（SO₄）₂和Ce₂（SO₄）₃的形成,从而提高了Ce-La/MgAl₂O₄-0.5催化剂抗硫中毒能力。     

湿法脱硫浆液中Hg2+的还原机制研究

针对燃煤电厂湿法脱硫浆液中Hg²⁺易被还原的特性,研究Hg²⁺在模拟湿法脱硫系统中的迁移机制,考察了浆液温度、pH值以及SO₃^2-、Cl^-、Ca²⁺、Mg²⁺浓度等因素对Hg²⁺还原性能的影响。结果表明,Hg²⁺还原率随着浆液中SO₃^2-浓度的增大而降低;pH值对Hg²⁺的还原呈先增加后降低的趋势,在pH值为5.5时还原率最高;温度的升高不利于浆液中稳定的二价汞盐络合物存在,导致Hg²⁺还原率增加;Ca²⁺、Mg²⁺以及Cl^-浓度的增加有利于形成稳定化合物,从而抑制Hg²⁺的还原。     

Fabrication of Electrospun PVDF Nanofibers with Higher Content of Polar β Phase and Smaller Diameter by Adding a Small Amount of Dioctadecyl Dimethyl Ammonium Chloride

In this work,the effect of dioctadecyl dimethyl ammonium chloride(DDAC,a kind of alkyl ammonium salt) on polar β phase content and the diameter of electrospun PVDF nanofibers was investigated for the first time.Our experimental results show that the diameter of the electrospun PVDF nanofiber could be largely reduced and the content of polar β phase also become dominant immediately by just adding a little amount of DDAC.When the mass fraction of DDAC reached 4%,the content of polar β phase increased by about 39.1% compared with PVDF nanofibers without DDAC.Besides,the crystallinity of PVDF nanofibers also increased with the addition of DDAC.Based on the results,the possible mechanism of cooperative effect between electrospinning and DDAC on fiber diameter and formation of β phase in PVDF was discussed.     

Structure-activity correlations of calcined Mg-Al hydrocalcites for aliphatic polycarbonate synthesis <Emphasis Type="Italic">via</Emphasis> transesterification process

Mg-Al mixed oxides with different Mg/Al molar ratio were prepared by thermal decomposition of hydrotalcitelike precursors at 500 °C for 5.0 h and used as catalysts for the transesterification of diphenyl carbonate with 1,4-butanediol to synthesize high-molecular-weight poly(butylene carbonate) (PBC). The structure-activity correlations of these catalysts in this transesterification process were discussed by means of various characterization techniques. It was found that the chain growth for the formation of PBC can only be obtained through connecting ―OH and ―OC(C)OC₆H₅ end-group upon removing the generated phenol, and the sample with Mg/Al molar ratio of 4.0 exhibited the best catalytic performance, giving PBC with M _w of 1.64 × 10⁵ g/mol at 210 °C for 3.0 h. This excellent activity depended mainly on the specific surface area and basicity rather than pore structure or crystallite size of MgO.     

Experimental and Theoretical Optimization of Radio Frequency Hollow Cathode Discharge

Plasma Chemistry and Plasma Processing - In this paper, the electron density in radio frequency (RF) hollow cathode discharge (HCD) is investigated in experiments and in simulation based on...     

点支撑预应力中厚矩形板的弯曲

基于Reissner-Mindlin一阶剪切变形板理论，讨论在预加面内机械荷载或温度场作用下，点支撑中厚矩形板的弯曲问题。温度场假定沿板表面为均布，沿板厚方向为线性分布的。利用考虑剪切变形影响的Timoshenko梁函数，采用Rayleigh-Ritz法给出不同边界条件下点支撑中厚板在横向荷载作用下的挠度和弯矩分布。结果表明，均匀温度场与预加面内压力将使板的挠度和弯矩增加。支撑点位置的变化、边界约束条件和横向剪切变形效应都对板的内力大小和分布有显著影响。     

等速上仰翼型动态失速现象研究

翼型大迎角绕流的静态失速将造成升力突降和气动性能急剧恶化，但利用非定常运动所产生 的动态失速效应，可以大大地延缓气流分离和失速现象的发生. 采用Rogers发 展的双时间步Roe格式，求解拟压缩性修正不可压N-S方程. 数值模拟了低雷诺数 ($Re=4.8 \times 10^{4}$)条件下NACA0015翼型作等速上仰($\alpha =0^{\circ} \sim 60^{\circ}$)的动态失速过程，同Walker的试验结果比 较，验证了计算结果的正确性. 研究了该过程中主涡、二次涡和三次涡的发展，升 力系数随攻角变化，以及不同上仰速度对动态失速效应所造成的影响.