CAS: 1345-05-7

Understanding Gravimetric Analysis

An inorganic chemical, titanium dioxide is used as a dye to help products achieve a certain appearance, including whitening a product. Some experts and publications have described it as being akin to a paint primer that's used before the color is added to food in order to give products a uniform shine. Its presence is common in many items beyond Skittles including coffee creamers, cake mixes, and chewing gum. It's also used for pigment and in cosmetics manufacturing.

Stability and darkening

As for titanium dioxide, the FDA approved titanium dioxide for use as a food additive in 1966. The last time the agency reviewed the additive’s safety, according to the Guardian, was in 1973.

To ensure the optimal precipitation percentage, it is important to carefully control these factors during the precipitation process. For example, a higher concentration of titanium sulfate will typically result in a higher precipitation percentage, but may also lead to the formation of impurities. On the other hand, a lower pH of the reaction mixture can promote the precipitation of titanium hydroxide, but may also result in a lower precipitation percentage.

TiO₂ comes in many different forms. However, only a few of these forms are considered food-grade (acceptable to be added to food). Many studies that raised concern about the safety of TiO₂, including the concern for genotoxicity, used forms of TiO₂ that are not considered acceptable for use in food and have different properties than food-grade TiO₂. Other studies did use food-grade TiO₂, but took steps to break the material down into smaller particles than what would normally be found in food.

Although barium sulfate is almost completely inert, zinc sulfide degrades upon exposure to UV light, leading to darkening of the pigment. The severity of this UV reaction is dependent on a combination of two factors; how much zinc sulfide makes up the pigments formulation, and its total accumulated UV exposure. Depending on these factors the pigment itself can vary in shade over time, ranging from pure white all the way to grey or even black. To suppress this effect, a dopant may be used, such as a small amount of cobalt salts, which would be added to the formulation. This process creates cobalt-doped zinc sulfide. The cobalt salts help to stabilize zinc sulfide so it will not have as severe a reaction to UV exposure.

2. Barite calcination method A solution of barium sulfide is prepared. The sulfuric acid and zinc oxide are reacted, purified by adding potassium permanganate and zinc powder, and compressed to obtain a zinc sulfate solution. Then, the prepared barium sulfide solution is mixed and subjected to a metathesis reaction to obtain a mixture of zinc sulfide and barium sulfate, and then the precipitate is subjected to pressure filtration, calcination, wet grinding, drying, and pulverization to obtain a zinc white product.