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Synthesis of special pigments

A study by means of TA methods

Journal of Thermal Analysis and Calorimetry
Authors: Z. Šolc and M. Trojan

Abstract  

Several TA methods (including dynamic TA, Q-TA, emanation and special conductometric TA) were used in investigations of condensed phosphate synthesis, and in the evaluation and control of the reactivity of the raw materials, when high-temperature stable pigments are developed. Conductometric TA occupies a special position because of its high sensitivity to most changes in crystal structure at the beginning of reactions.

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Journal of Thermal Analysis and Calorimetry
Authors: C. Xavier, C. Costa, S. Crispim, M. Bernardi, M. Maurera, M. Conceiçăo, E. Longo and A. Souza

Abstract  

The pigments used in ceramic applications are of nature predominantly inorganic and they should be thermally stable, insoluble in glazing, resistant to the chemical and physical agents' attacks. This work aimed at the synthesis by the polymeric precursor method of ZrO2-based inorganic pigments, doped with Fe, Ni, Co, Cr and Cu cations. The fired pigments were characterized by thermogravimetry (TG), differential thermal analysis (DTA) and X-ray diffraction (XRD). Among the metals used to zirconium-doping, the best result was achieved with the cations Cu, which presented the monophase pigment, even as 20 mol% of dopant. Up to the temperature of 1000C the pigments presented a good thermal stability.

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95 38 50 Fadeel, A. A. (1962) Location and properties of chloroplasts and pigment determination in roots. Physiol. Plant. 15 , 130

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Abstract  

The color efficiency of ceramic glaze blue pigments obtained by the Pechini method was presented in this work. The fired pigments and enameled samples were characterized by thermogravimetry (TG) and differential thermal analysis (DTA), XRD, UV-VIS-NIR spectroscopy and CIE-L*a*b* color-measurements. The pigments obtained by the Pechini method present a better solubility in the molten glazes than the pigments obtained by the mechanical mixture of the precursor oxides.

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A wide variety of pigments, like chlorophyll, carotenoids and phycobiliproteins, which exhibit colours ranging from green, yellow, brown to red are present in algae. Increasing awareness of harmful effects of synthetic dyes and inclination of society towards the usage of natural products, such as plant / microbial based colours in food and cosmetics, has led to the exploitation of microalgae as a source of natural colours. Algal pigments have great commercial value as natural colorants in nutraceutical, cosmetics and pharmaceutical industry, besides their health benefits. Spirulina, Dunaliella capsules are now commonly prescribed health foods for improving vitality and longevity of human beings. This review describes the distribution, structure of these pigments in algae, with emphasis on specific techniques for extraction and purification, along with different methods of biomass production and commercially feasible techniques documented in literature. An overview of the industrial applications of these natural colouring agents in diagnostics, food and cosmetics industry is also provided.

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Journal of Thermal Analysis and Calorimetry
Authors: Z. Yermiyahu, I. Lapides and S. Yariv

Abstract  

An intense blue organo-clay color pigment was obtained by adding naphthyl-1-ammonium chloride to a Na-montmorillonite aqueous suspension followed by treatment with sodium nitrite. This treatment resulted in the synthesis of the azo dye 4-(1-naphthylazo)-1-naphthylamine adsorbed onto the clay. The pigment was subjected to thermo-XRD-analysis and the diffractograms were curve-fitted. Heating naphthylammonium-montmorillonite at 360°C resulted in the evolution of the amine at temperatures lower than those required for the formation of charcoal and consequently the clay collapsed. On the other hand, heating the pigment at 360°C resulted in the conversion of the adsorbed azo dye into charcoal. The clay did not collapse, thus proving that the azo dye was located inside the interlayer space. Before the thermal treatment a short basal spacing in the pigment compared with that in the ammonium clay (1.28 and 1.35 nm, respectively) indicated stronger surface π interactions between the clayey O-plane and the azo dye than between this plane and naphthylammonium cation. The amount of dye after one aging-day of the synthesis-suspension increased with [NaNO2]/[C10H7NH3] ratio but did not increase with naphthylammonium when the [NaNO2]/[C10H7NH3] ratio remained 1. After 7 and 56 aging days it decreased, indicating that some of the dye decomposed during aging.

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Pollack Periodica
Authors: Viola Hospodarova, Jozef Junak and Nadezda Stevulova

] Sulcova P. Options synthesis and application testing of inorganic pigments , In: Zborník príspevkov zo VII. konferencie s mezinárodnou účasťou Partikulárne látky vo vede, priemysle a v životnom

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, G. ( 1994 ): Pigment of Monascus. J. Food Sci. , 59 , 862 – 865 . Booyens , J. , Labuschagne , M.C. & Thantsha , M.S. ( 2014 ): In

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Introduction The research activities in the field of ceramic pigments are focused on investigation of pigments with thermal stability, ecological purity and interesting colour hues. The most requisite hues are yellow, pink

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Journal of Thermal Analysis and Calorimetry
Authors: S. C. Souza, M. A. F. Souza, S. J. G. Lima, M. R. Cassia-Santos, V. J. Fernandes Jr., L. E. B. Soledade, E. Longo, A. G. Souza and I. M. G. Santos
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