Le lithopone a été découvert dans les années 1870 par DuPont. Il a été produit par la Krebs Pigments and Chemical Company, entre autres¹. Il se faisait en différents grades, en fonction de la teneur en sulfure de zinc. Les qualités « bronze » et « or » contenaient 40 à 50 % de sulfure de zinc, ce qui les rendaient particulièrement couvrantes². Bien que ce pigment ait atteint son pic de popularité autour de 1920, il s'en produisait encore annuellement plus de 220 000 tonnes en 1990. Il est principalement utilisé dans les peintures, les pâtes et les plastiques³.

As mentioned above, these oxide NPs are harmful in part because both anatase and rutile forms are semiconductors and produce ROS. Particularly, P25 kind has band-gap energies estimated of 3.2 and 3.0 eV, equivalent to radiation wavelengths of approximately 388 and 414 nm, respectively. Irradiation at these wavelengths or below produces a separation of charge, resulting in a hole in the valence band and a free electron in the conduction band, due to the electron movement from the valence to conduction bands. These hole–electron pairs generate ROS when they interact with H₂O or O₂ [43,44]. It was described that they can cause an increase in ROS levels after exposure to UV-visible light [45]. The NBT assay in the studied samples showed that bare P25TiO₂NPs produce a large amount of ROS, which is drastically reduced by functionalization with vitamin B2 (Fig. 5). This vitamin, also known as riboflavin, was discovered in 1872 as a yellow fluorescent pigment, [46] but its function as an essential vitamin for humans was established more than sixty years later, and its antioxidant capacity was not studied until the end of the XX century [47,48]. This antioxidant role in cells is partially explained because the glutathione reductase enzyme (GR) requires it for good functionality. This enzyme is the one in charge of the conversion of oxidized glutathione to its reduced form which acts as a powerful inner antioxidant and can quench the ROS [49,50]. The cost of this action is that the glutathione is converted to the oxidized form and needs to be recovered by the GR. Consequently, the cells need more vitamin B2. Another glutathione action is the protection against hydroperoxide. This activity is also mediated by riboflavin. Therefore, local delivery of this vitamin seems to significantly help the cells in their fight to keep the oxidative balance, once they are exposed to high levels of ROS.

Lithopone

See also

In the automotive industry, for example, MBR9668 is used in primers and finish coats to provide superior color retention and gloss. With durability being a key concern for automotive manufacturers, utilizing rutile titanium dioxide in coatings enhances the longevity of the vehicle's exterior finishes, ensuring that they remain vibrant and effective for years under various conditions.

Drivers

Comparisons

ZnSO4 – BaS ➔ BaSO4*ZnS