光催化降解丙酮的原位红外研究

对催化剂.Pt/V2O5/MgF2在反应温度为120～150℃之间进行了光催化降解丙酮的研究,研究在可见光下进行,发现反应温度对光催化反应有明显的影响.在排除热反应的情况下,温度升高能加速丙酮的光催化反应.丙酮的光催化反应是从它的甲基上开始的,可能先生成了CH3COCH2O-吸附物,它进一步被氧化成丙酮醛、丙酮酸以及碳二醛、乙酸和碳一吸附物种,最终氧化成CO2和水.在没有光和较低的反应温度下,有CO生成,但是在可见光的照射下CO被迅速转化成CO2.研究表明,V2O5/MgF2与Pt/V2O5/MgF2为可见光条件下具备活性的光催化剂.     

我国X射线光谱现场分析技术研究进展

X射线光谱现场分析技术是在现场工作条件下对待测目标体中元素进行快速定性和定量分析的仪器分析技术,被广泛应用于一些大型分析仪器和化学分析方法所不能直接应用的领域。该文回顾了近二十年来我国X射线光谱现场分析技术的研究进展。从现场原位分析和现场取样分析两个角度,评述了现场X射线光谱仪的研究进展和主要技术特征;探讨了X射线光谱现场分析数据处理的关键技术问题,概括了X射线仪器谱解析方法的创新性和演变规律;介绍了我国现场X射线光谱分析在地质普查、环境污染调查、文物现场鉴定、合金分析中的重要应用;评价了国际上X射线光谱现场分析仪的研究现状和进展。提出了X射线光谱现场分析技术的研究方向,以期在更多的应用领域得到长足发展。     

原位法常压干燥制备疏水SiO2气凝胶及其热稳定性

在正硅酸乙酯(TEOS)酸碱两步催化的溶胶-凝胶过程中, 加入干燥控制化学添加剂(DCCA)N,N-二甲基甲酰胺(DMF)和三甲基氯硅烷(TMCS)的混合溶液, 进行原位疏水改性处理, 并结合常压干燥工艺制备了高比表面积的疏水SiO2气凝胶. 利用N2物理吸附, 全自动X射线衍射仪(XRD), 傅立叶变换红外光谱仪(FTIR), 扫描电子显微镜(SEM)等对样品的形貌结构进行了表征. 实验结果表明, 原位疏水改性比非原位疏水改性制备的SiO2气凝胶具有更大的比表面积, 可达979 m2·g-1, 气凝胶表面存在憎水性基团—CH3, 有良好的疏水性. 500 ℃热处理后, 气凝胶因失去大量的—CH3基团, 由憎水性转为亲水性; 800 ℃高温热处理后, 疏水SiO2气凝胶仍处于非晶态, 具有良好的热稳定性能.     

膜相渗透原位化学聚合法制备PAn/CA复合透膜

采用膜相渗透原位化学聚合法,使苯胺(An)原位化学聚合于醋酸纤维素(CA)基体膜的微孔壁中,得到均匀分布的PAn/CA复合导电透膜.通过研究聚合反应条件对复合透膜的导电性能和CO₂/O₂表观分离性能的影响,获得了制备性能较优的PAn/CA复合导电透膜的适宜条件.结果表明,采用膜相渗透化学原位聚合法制备的PAn/CA复合导电透膜,平均孔径明显变小,孔径分布变窄,具有优于CA基体膜的微孔结构形态.     

Stripping voltammetry for the determination of trace metal speciation and in-situ measurements of trace metal distributions in marine waters

Progress in marine chemistry has been driven by improved sampling and sample handling techniques, and developments in analytical chemistry. Consequently, during the last 20 years our understanding of marine trace metal biogeochemistry has improved a great deal. Stripping voltammetric techniques (anodic stripping voltammetry and adsorptive cathodic stripping voltammetry) have made an important contribution to this understanding. The selectivity and extremely low detection limits have made stripping voltammetry a widely used technique for trace metal speciation and trace metal distribution measurements in seawater. Stripping voltammetry is very suitable for ship-board and in-situ applications because of the portability, low cost and capability for automation of the voltammetric instrumentation. Future developments in stripping voltammetry can be expected in the field of stand-alone submersible voltammetric analysers, capable of continuous trace metal measurements. Future applications of stripping voltammetry can be found in the interactions between trace metal speciation and growth and the functioning of organisms in pristine and metal polluted marine waters.     

现场拉曼光谱研究聚吡咯的去质子化和氧化降解

利用电化学现场拉曼光谱结合循环伏安法,研究了中性和碱性溶液中聚吡咯（ＰＰＹ）膜的行为及其结构．结果表明,氧化态ＰＰＹ中吡咯环Ｎ原子上的Ｈ失去发生去质子化,形成一种醌式结构．由于该醌式结构的出现使ＰＰＹ的Ｃ＝Ｃ伸缩振动峰发生分裂,且因该醌式结构不能被进一步氧化,以致ｐＨ值增大,去质子化程度提高,ＰＰＹ变得较难被氧化,而使其可逆性也受到一定程度的破坏,在ｐＨ＝１３的强碱性溶液中,ＰＰＹ膜在正于ＯＶ的电位区间内发生降解,该降解过程可能涉及到ＰＰＹ的吡咯环单元结构的破坏．     

Catalytic conversion of defatted rice bran into value added chemicals using copper ferrite: A sustainable approach

The most crucial and demanding universal issue lies in the enrichment of sustainable drive technology. As traditional resource, petrochemical becomes increasingly scarce in the future; mankind must turn to renewable alternatives to yield liquefied fuels and valuable commodities through sustainable process. It has been reported that furan compounds serve as an excellent platform molecule derived from defatted rice bran. The current work aims at the synthesis of copper ferrite nano catalyst by microwave assisted solution incineration approach. The catalytic properties stood verified by X-ray diffraction, SEM, EDAX and BET techniques. The catalytic performance of the copper ferrite catalyst were reinforced through in-situ microwave assisted acetalization reaction of furfural with discrete solvents like methanol, ethanol, and 1-propanol at optimum reaction conditions for the preparation of wide range of commodity chemicals such as carboxylic acids, alkyl esters, di alkyl acetals, di ketones which are of commercial importance. The comparative study of relative yield of the products with different solvents is reported. The formation of the value-added products were confirmed by GC-MS, FT-IR technique. The catalysts from the reaction mixture are recovered by magnetic field.     

In-situ experiment tests and particulate simulations on powder paving process of additive manufacturing

In this work, in-situ experimental tests are first performed to investigate the powder spreading process of additive manufacturing, where different kinds of scrapers and spreading speeds are employed. Detailed kinetic behaviours of individual powder particles are discussed by discrete element method simulations. It is found that the decrease of inclination angle of the scraper improves the powder pressure and compaction in the spreading process, leading to a denser powder flow and thus a denser powder bed. The increase of spreading speed also improves the powder pressure and compaction in the spreading process. However, the powder flow becomes looser due to the volume dilation, and thus the quality of the paved powder bed decreases. In industrial applications, if the higher powder spreading speed is employed to improve the processing efficiency, the scraper with a smaller inclination angle can be used to ensure the powder bed quality.