The effect of heavy metals in water on the optical properties of silk
Abstract
The elevated concentration of heavy metals in unwinding baths adversely affects unwindability. Compared to low iron concentrations, unwindability decreases by 2.1–2.6%, whereas the presence of copper reduces it by 2.4–4.9%, and aluminum by 0.5–2.7%. Additionally, trace amounts of iron in the unwinding bath diminish raw silk yield by 0.7–1.3%, copper by 1.1%, and aluminum by 0.6–1.2%. Furthermore, the presence of heavy metals in water negatively impacts the optical properties of raw silk. Even minimal iron content imparts a gray or brown tint to the silk, diminishing its luster and whiteness. Copper, like iron, negatively affects the optical properties of silk, being absorbed into raw silk and causing it to become bluish. Aluminum also colors raw silk gray or reddish. As a result, the optical properties of silk, such as luster and whiteness, are reduced.