利用标志法研究钒—硅酸锆蓝色颜料的生成机理

标志法用来研究钒-硅酸锆蓝色颜料形成过程中的离子移动问题,借此了解该颜料的生成机理。结果表明Si^4 和Zr^4 中Si^4 是唯一可以移动的离子;NaF的加入有利于SiO2的玻璃化,因而对硅离子的迁移有一定贡献,但其移动更依赖于NaF和NH4VO3反应所形成的液相。此外,ZrO2的溶解也是硅酸锆生成的一个限制因素。     

工艺因素对钒锆蓝颜料呈色的影响

探讨了工艺因素对钒－硅酸锆蓝色颜料合成的影响,用XRD和UV－V光谱对样品进行了表征,得到一些有益的结论。     

天然色素超临界CO2萃取技术研究进展

本文介绍了超临界萃取技术在食用天然色素研发中的应用现状,对近十年来超临界CO2萃取天然色素的研究报告做了统计,重点介绍了辣椒红素、胡萝卜素、番茄红素、玉米黄色素等超临界CO2萃取技术的研究进展.     

黑色耐高温铁酸锰颜料生产工艺研究

总结了黑色耐高温铁酸锰颜料生产工艺研究过程,包括前驱体制备、煅烧工艺、研磨工艺,表面包膜工艺、表面改性工艺、易分散微细化工艺等。     

机械研磨-煅烧制备SiO_2微球/TiO_2复合颜料试验研究

采用搅拌磨中二氧化硅微球(MS-SiO_2)和偏钛酸(TiO_2·n H2O)湿法研磨、研磨产物煅烧方式制备了MS-SiO_2/TiO_2复合颜料,对制备过程的主要影响因素进行考察和优化,对其结构和性能进行表征。结果表明,MS-SiO_2/TiO_2·n H2O共混研磨过程固含量、机械力、p H值和产物煅烧温度对MS-SiO_2/TiO_2复合颜料性能有显著影响。MS-SiO_2/TiO_2中SiO_2颗粒均匀包覆在MS-SiO_2表面,SiO_2主要为金红石相;MS-SiO_2/TiO_2具有和钛白粉相当的颜料性能。     

红枣红色素稳定性的研究

对红枣红色素的稳定性进行了研究,结果表明：红枣红色素对光、热稳定;pH值对红枣红色素的影响明显,在pH8～11之间,该色素较稳定;金属离子K^＋、Ca^2＋、Na^＋、Mg^2＋、Zn^2＋对该色素的稳定性较好,Cu^2＋、Al^3＋、Fe^3＋对其稳定性有明显的影响或破坏作用;该色素抗氧化性和还原性不强;苯甲酸钠和蔗糖溶液对红枣红色素的稳定性影响较小。     

Structural analysis and characterization of doped spinel Co2−xMxTiO4 (M=Mg2+, Mn2+, Ni2+, Cu2+ and Zn2+) coated mica composite pigments

A new kind of composite mica pigments were prepared by coating Co_2−xM_xTiO₄ composite oxide nanoparticles onto mica, to investigate the effects of doping ions Mg²⁺, Mn²⁺, Ni²⁺, Cu²⁺ and Zn²⁺ on the properties of the doped composite pearlescent pigments, such as the crystal structure, color and shading power. The structure, morphology, color and shading power of the coated pigments were characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis spectrophotometer and CIE L*a*b* methods. SEM images of coated pigments showed that mica were coated uniformly with a single layer of dispersed nanoparticles. Research of the doped composite pigments showed that the doping ions had entered into the spinel crystal structure, forming a new kind of composite mica pearlescent pigments coated with Co_2−xM_xTiO₄. For the analysis of color and shading power of the pigments, doping of Ni²⁺ and Zn²⁺ can improve the color and shading power of the doped pigments, but the larger dosage of Zn²⁺ doping can weaken the color and shading power of the doped pigments. Doping of Mg²⁺, Mn²⁺ and Cu²⁺ metal ions can also weaken the color and shading power of the doped pigments.     

Combined use of chitosan and alginate in the treatment of wastewater

This study examined the combined use of chitosan and sodium alginate in the treatment of wastewater containing heavy‐metal ions and dye. Wastewater samples were divided into two equal parts before chitosan and sodium alginate solutions were added to each part. When these two solutions were mixed together, the heavy‐metal ions and dye molecules were separated from the water as the positively charged chitosan and the negatively charged sodium alginate precipitated each other. The effects of the concentration and ratio of chitosan and sodium alginate, the treatment temperature, and the time on the efficiency of metal‐ion and dye removal were investigated. The results showed that when used in combination, sodium alginate and chitosan were effective in removing copper, cadmium, lead, and silver ions as well as acid dye molecules © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3581–3587, 2007     

Effect of acetaldehyde and several acids on the formation of vitisin A in model wine anthocyanin and colour evolution

Summary It was found that the reaction between malvidin 3-glucoside and added pyruvic acid (PA), leading to the formation of vitisin A in model wine solutions, was not prevented by the addition of either acetaldehyde (A) or several organic acids. The acylated forms of vitisin A (3-acetylvitisin A and 3- p -coumarylvitisin A) were formed through the interaction of malvidin 3-acetylglucoside and malvidin 3- p -coumarylglucoside. Disappearance of the three main anthocyanins (malvidin 3-glucoside, malvidin 3-acetylglucoside and malvidin 3- p- coumarylglucoside) from the model wine with time followed first order kinetics. Acetaldehyde had the effect of increasing the total amount of these losses but producing smaller amounts of vitisin A. During ageing model solutions developed some browness. The brownest solution was obtained without A and a reduced rate of browning was found in the presence of A. This latter result can be explained by the assumption of a superimposition of a blueing effect upon reactions of A with anthocyanins. In the presence of PA the formation of vitisin A compounds gave an intermediate colour, contributing a reddish hue to the solution. A good correlation (r²= 0.96) between the percentage of vitisin A, of the total anthocyanins and the hue angle was observed. The addition of large amounts of organic acids that are normally found in wine into the model solutions did not lead to the formation of new anthocyanins. The linear loss of PA in all model systems indicates that a first order reaction occurs and 35.35 times more PA than total anthocyanin was lost to form the new compounds.     

Xanthylium salts formation involved in wine colour changes

Summary The reaction of (+)-catechin in wine-like model solution was investigated. First appearance of colourless dimeric compounds consisting of two flavanol units linked by carboxy-methine bridge was observed. Their isolation and further incubation was found to yield two types of yellowish pigments showing visible absorption maxima at 440 and 460 nm, respectively. Mass spectroscopy (MS) spectral analysis showed that the first type were xanthylium salt pigments formed by dehydration of the colourless compounds followed by an oxidation process. The loss of a water molecule was shown to take place between two A ring hydroxyl groups of the colourless dimers. The second type were shown to be ester derivatives of the first ones. Thus ethylester of xanthylium salt was obtained and fully characterized by mass and nuclear magnetic resonance (NMR) spectroscopy. Esterification was found to involve the colourless compound before dehydration and thus a general scheme for xanthylium salt formation was postulated. The proposed scheme constitutes a new xanthylium formation pathway as up to now only anthocyanin-flavanol reactions were supposed to form xanthylium salt derivatives during wine ageing. This work also provides new support to the contribution of xanthylium salt in colour evolution observed during wine ageing which is generally expressed in an increase of absorption in the 400–500 nm, region of xanthylium salt absorption maxima.