KF/Al2O3的制备、表征及催化合成乙二醇丙烯基醚

采用浸渍法制备KF/Al2O3固体碱催化剂,催化丙烯醇与环氧乙烷（EO）反应合成乙二醇丙烯基醚。考察了催化剂焙烧温度、氟化钾（KF）负载量对催化性能的影响,并采用X-射线衍射（XRD）、扫描电镜（SEM）等对催化剂进行了表征。结果表明：KF负载量为30%,焙烧温度为550℃时,催化剂对丙烯醇和EO反应的催化活性最高。KF/Al2O3固体碱催化剂用于催化合成乙二醇丙烯基醚的最佳工艺条件为：反应温度100℃,反应压力为0.20-0.35MPa,催化剂用量为1.5%,n（丙烯醇）∶n（EO）为5∶1,反应时间为2h,EO转化率达97.35%。     

Effect of sintering atmosphere and lithium ion co-doping on photoluminescence properties of NaCaPO4:Eu phosphor

This paper reports on the photoluminescence properties of Na_1−yLi_yCa_1−xPO₄:_xEu²⁺ phosphors synthesized by a solid state reaction method. The prepared phosphors have been thoroughly characterized by means of X-ray diffraction (XRD), Field-emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectrum (FTIR), Raman spectrum, Thermo gravimetric and differential thermal analysis (TG–DTA) and photoluminescent spectral measurements. The structure of Na_1−yLi_yCa_1−xPO_4:xEu²⁺ phosphors were found to be orthorhombic in nature with a sphere-like morphology and having the particle size in micrometer range. The excitation spectra of NaCaPO₄:Eu²⁺ phosphors revealed a broad excitation band having its maximum intensity at 373 nm and ranging from 250 m to 450 nm. Incidentally, it matches well with the ultraviolet (UV) radiation of light-emitting diodes (LEDs). Upon 373 nm excitation, these phosphors exhibited intense bluish-green emission band centered at 505 nm. The effect of sintering atmospheres and co-doping of lithium ions on the photoluminescence properties of the NaCaPO₄:Eu²⁺ phosphors were studied and explained suitably. The obtained results indicate that the prepared NaCaPO₄:Eu²⁺ phosphors are promising bluish-green candidates for the phosphor-converted white LED applications.     

Electrochemical decomposition of CO2 and CO gases using porous yttria-stabilized zirconia cell

Electrochemical decomposition of CO₂ and CO gases using a porous cell of Ru-8 mol% yttria-stabilized zirconia (YSZ) anode/porous YSZ electrolyte/Ni–YSZ cathode system at 400–800 °C was studied by analyzing the flow rate and composition of outlet gas, current density, and phases and elementary distribution of the electrodes and electrolyte. A part of CO₂ gas supplied at 50 ml/min was decomposed to solid carbon and O₂ gas through the cell at the electric field strengths of 0.9–1.0 V/cm. The outlet gas at a flow rate of 3 ml/min included 61–63% CO₂ and 37–39% O₂ at 700–800 °C and the outlet gas at a flow rate of 50 ml/min included 73–96% (average 85%) CO₂ and 4–27% (average 15%) O₂ at 800 °C. On the other hand, the supplied CO gas was also decomposed to solid carbon, O₂ and CO₂ gases at 800 °C. The fraction of outlet gas at a flow rate of 50 ml/min during the CO decomposition at 800 °C for 5 h was 11–36% CO, 59–81% O₂ and 2–9% CO₂. The detailed decomposition mechanisms of CO₂ and CO gases are discussed. Both Ni metal in the cathode and porous YSZ grains under the DC electric field have the ability to decompose CO gas into solid carbon and O²⁻ ions or O₂ gas.     

Effect of MgO addition on the crystallization and in vitro bioactivity of glass ceramics in the CaO–MgO–SiO2–P2O5 system

CaO–MgO–SiO₂–P₂O₅ glass ceramics were successfully prepared by sintering the sol–gel-derived powders. The effects of MgO addition on the samples crystallization and structure were investigated by means of differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). In addition, samples degradation and in vitro bioactivity assays were also evaluated. With more MgO addition, the glass ceramics crystallization kinetics under non-isothermal conditions changed from bulk crystallization to surface crystallization, and new crystal phases of Ca₂MgSi₂O₇ and SiO₂ were induced. In addition, it is observed that with increasing MgO concentration, the glass ceramics degradability gradually decreased and the formation of apatite was delayed.     

Preparation of SiC nanowires-filled cellular SiCO ceramics from polymeric precursor

SiC nanowires-filled cellular SiCO ceramics were prepared using polyurethane sponge as a porous template infiltrated with silicone resin by pyrolysis at 1400 °C under Ar atmosphere. The pyrolysis temperature was an important parameter affecting the formation of SiC nanowires. The as-prepared sample obtained at 1000 °C was composed of SiCO glasses and turbostratic carbon. The SiCO ceramic was further converted into SiO₂ crystals and amorphous carbon by pyrolysis at 1200 °C. With the increasing pyrolysis temperature, SiC nanocrystals embedded in the non-crystalline SiCO matrix were observed. Furthermore, the SiC nanowires were formed in the pores of the SiCO ceramic. The diameters of the SiC nanowires are in the range 80–150 nm and the lengths are up to several tens of micrometers. The growth mechanism of the nanowires was supported by the vapor-solid mechanism.     

Vacuum Pressure Swing Adsorption to Produce Polymer-Grade Propylene

We have evaluated the Vacuum Pressure Swing Adsorption (VPSA) technology to separate propane–propylene streams to produce polymer-grade propylene. Zeolite 4A is used as kinetic adsorbent since propylene diffuses much faster than propane. A single VPSA process is able to produce propylene with purity higher than 99.6%. However, propylene recovery is only 67% and therefore a second stage is used. In this VPSA unit, zeolite 4A with smaller crystal radius is employed to reduce kinetic limitations. The second VPSA (tail unit) produces purified propane and recovers propylene that is recycled to the feed of the first VPSA (front unit). Linking these two VPSA units allows us to produce polymer-grade propylene (PGP) recovering 95.9% of the propylene. Comparing the performance of this process with distillation, there is a significant decrease in the separation volume. However, further efforts are necessary to reduce the power consumption of VPSA which is still slightly higher than for distillation.     

Nanofiltration of Hormone Mimicking Trace Organic Contaminants

Abstract

The removal mechanisms of three hormone mimicking organic compounds by nanofiltration (NF) membranes have been examined. Two NF membranes having different pore sizes were used in laboratory‐scale nanofiltration experiments with feed solutions spiked with a hormone mimicking compound—nonylphenol, tert‐butylphenol, or bisphenol A. Retention of the compounds was determined at various solution chemistries, namely aqueous solution pH, ionic strength, and presence of natural organic matter. The nanofiltration behavior of the selected hormone mimicking compounds appears similar to that of natural hormones as reported in our previous work. While the solution pH can dramatically influence the retention of hormone mimicking compounds by a loose NF membrane, ionic strength does not affect the nanofiltration of such contaminants. However, in the presence of natural organic matter in the feed solution, ionic strength appears to play a significant role in solute‐solute and solute‐membrane interactions, resulting in increased retention due to partitioning of the hormone mimicking compounds onto organic matter at a higher ionic strength.     

Application of Slurry Type Photocatalytic Oxidation‐Submerged Hollow Fiber Microfiltration Hybrid System for the Degradation of Bisphenol A (BPA)

Abstract

A pilot scale, slurry type photocatalytic reactor, followed by submerged hollow fiber microfiltration (MF) membrane hybrid system was evaluated for simultaneous and complete destruction of toxic organic chemical bisphenol A (BPA) and separation of photocatalyst TiO₂; in order to obtain a reusable quality water. With simple modification to the treatment operation, the effect of photocatalytic reaction at modest variations in temperature was examined. Adsorption pretreatment was carried out prior to photocatalysis (UV/TiO₂). BPA adsorption ability on TiO₂ was very less (about 15%) at 25°C. However, adsorption pretreatment followed by photocatalytic oxidation (UV/TiO₂) at an elevated nearly constant temperature (about 70°C) helped in increasing the BPA degradation efficiency. The effect of ozone introduction into the treatment stream was also analyzed. Applying ozone along with UV/TiO₂, brought about a synergistic effect on BPA degradation. Within 3 h, entire 10 ppm of BPA and the by‐product organic compounds were completely removed. TiO₂ particle separation performance using hollow fiber membrane was enhanced by adopting a two‐stage coagulation/sedimentation pretreatment. With initial turbidity of 4000 NTU, the turbidity of the final permeate water was well below 0.1 NTU. Almost complete removal of particles was achieved. Some of the main advantages of this hybrid treatment system include, large‐scale treatment, complete and efficient BPA and its organic intermediates degradation, TiO₂ easily separated after treatment and capable for reuse as it is free from chemical coagulant contaminants, reusable quality water is obtained, and the system has the potential for continuous operation with simple process modifications.     

可生物降解微球甲型肝炎减毒活疫苗口服免疫恒河猴的免疫应答

目的 探索用一种新型的甲型肝炎减毒活疫苗及其免疫途径。方法 用可生物降解的材料聚乳 酸／乙醇酸（ＰＬＡ／ＰＬＧ）包裹甲型肝炎减毒活疫苗,制成微球型疫苗,检测微球的大小及在体外病毒释放的状况,和口 服免疫恒河猴后病毒在体内繁殖及免疫应答状况。结果 微球大小在６～１０μｍ范围,体外病毒抗原释放长达２７ｄ 左右,体外抗原释放高峰在３～７ｄ,口服免疫恒河猴后,约１ｗ左右开始排毒,以后一直呈间断排毒。抗体应答于第 ３ｗ出现,高峰期在５～６ｗ,达１２６１ＭｍＩＵ／ｍｌ,随后逐渐下降,口服加强免疫后,抗体回升,野毒株攻击后,抗体再度回升 达１２４４ｍＩＵ／ｍｌ。结论 微球型甲型肝炎减毒活疫苗口服免疫恒河猴后,能引起一定水平的免疫应答。     

甲型肝炎减毒活疫苗检定方法精确度的探讨

目的 提高甲肝减毒活疫苗检定方法的精确度。方法 比较不同刑量组与剂量组不同的试验数,以 及采用点斜法与Ｒｅｅｄ－Ｍｕｅｎｃｈ法计算ＴＣＩＤ５０。结果 通过比较４种不同的试验设计,发现随着稀释倍数减小或／和各 稀释度试验管数增加,ＴＣＩＤ５０的标准误减小,以减小稀释倍数同时增加各稀释度试验管数,其标准误的缩小最为明显。 点斜法计算的ＩＣＩＤ５０９５％可信区间较Ｒｅｅｄ－Ｍｕｅｎｃｈ法为窄。结论 减小稀释倍数同时增加各稀释度试验管数,并采 用点斜法计算ＴＣＩＤ５０,能使疫苗检定方法的精确度满足规范化甲肝活疫苗滴定的要求。