Resumen–En este artículo se discute el descubrimiento del litopón fosforescente en dibujos a la acuarela por el artista americano John La Farge, fechados de 1890 a 1905, y la historia del litopón en la industria de los pigmentos a finales del Siglo XIX y principios del Siglo XX. A pesar de tener muchas cualidades deseables para su uso en pintura para acuarela o pinturas al óleo blancas, el desarrollo del litopón como pigmento para artistas fue obstaculizado por su tendencia a oscurecerse con la luz solar. Su disponibilidad para los artistas y su adopción por ellos sigue siendo poco clara, ya que por lo general los catálogos comerciales de los coloristas no eran explícitos al describir si los pigmentos blancos contenían litopón. Además, el litopón se puede confundir con blanco de plomo durante el examen visual, y su fosforescencia de corta duración puede ser fácilmente pasada por alto por el observador desinformado. A la fecha, el litopón fosforescente ha sido documentado solamente en otra obra mas: una acuarela por Van Gogh. Además de la historia de la fabricación del litopón, el artículo detalla el mecanismo para su fosforescencia, y su identificación con la ayuda de espectroscopía de Raman, y de espectrofluorimetría.
Below are selected applications of photocatalytic pollutant decomposition processes on titanium oxide:
1. Self-cleaning surfaces: for the production of glass for spotlights, traffic lights, car mirrors, window panes, for road paints, for covering sound-absorbing screens and tunnel walls.
2. Air cleaning and odor removal: filters that are used in enclosed spaces (e.g. public toilets) or filters for air-conditioning equipment.
3. Water treatment: groundwater treatment installations, water purification installations in the intakes of drinking water from rivers.
4. Self-disinfecting materials: towels, linings, clothing, equipment in hospitals, wall surfaces of operating rooms.
5. Removal of lesions: anti-cancer therapy.
First, the ammonia leaching method is used as a technical means for the effective treatment of acid leaching slag, and the nano nitrite powder is prepared under a weak alkaline ( Ή 8 8.5 to 10) ammonia environment. In an alkaline environment, some metal impurities such as The solubility of Ca, Mg, Fe and Al hydroxides is low, and the impurities entering the final immersion liquid in the selective leaching of ammonia-ammonium sulfate are reduced, thereby ensuring the quality of the product; the traditional acid method for preparing lithopone is because of the zinc calcination. In the roasting and reduction process of the alkalized alkali, the elemental sulfur and sulfite are more or less produced, and the prepared white powder has a yellowish color, and the metathesis reaction of the patent is carried out in an ammonia solution (alkaline). The final product obtained is sulfate, which is quickly and thoroughly added by desulfurization through 3⁄40 2 , and the whiteness of the product can be ensured without high temperature calcination; the equipment requirement is lower than that of sulfuric acid leaching, and the ordinary steel leaching tank can complete the leaching; The environmental pollution problem of acid leaching residue, especially effectively solves the environmental pollution of heavy metals such as zinc, copper, lead, cadmium and arsenic in acid leaching residue and the influence of acid ions on the storage environment. Realize the recycling of high-value metal zinc in acid leaching slag, realize the acidity improvement of soil and have the comprehensive advantages of low cost, energy saving and environmental protection.
Lithopone was discovered in the 1870s by DuPont. It was manufactured by Krebs Pigments and Chemical Company and other companies.[2] The material came in different seals, which varied in the content of zinc sulfide. Gold seal and Bronze seals contain 40-50% zinc sulfide, offering more hiding power and strength.[3] Although its popularity peaked around 1920, approximately 223,352 tons were produced in 1990. It is mainly used in paints, putty, and in plastics.[1]
Très apprécié dans le travail des Icônes pour éclaircir, mais également pour les vernis, émaux, peintures, plastique et papier. A l'inverse, ne pas utiliser ce produit dans les applications cosmétiques, comme additif alimentaire ou comme additif médicamenteux.