Hydrogen peroxide (H2O2) is obtained by electrolytic oxidation of sulphuric acid followed by distillation, or by treating barium or sodium peroxide or potassium persulphate with an acid. It is a colourless liquid with the appearance of ordinary water. It may have a syrupy consistency and corrodes the skin when concentrated. It is transported in carboys.
Hydrogen peroxide is very unstable in an alkaline medium, especially when exposed to heat or light. It nearly always contains small amounts of stabilisers (boric or citric acid, etc.) to prevent decomposition; such mixtures remain in this heading. This heading also includes hydrogen peroxide, solidified with urea, whether or not stabilised. Hydrogen peroxide is used for bleaching textiles, feathers, straw, sponges, ivory, hair, etc. It is also used for vat‑dyeing, for purifying water, for restoring old pictures, in photography and in medicine (as an antiseptic and haemostat). Presented as a medicament in measured doses or in forms or packings for retail sale, hydrogen peroxide falls in heading 30.04.
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