Aqueous solution of Sn(II) carboxylic acid complex for reducing chromium (VI) ions into chromium (III)

摘要

Disclosed is an additive when used to reduces Cr(VI) ions to Cr(III) ions, comprising an aqueous solution of a complex of tin(II), and a carboxylic acid such as gluconic acid or a salt thereof, wherein the additive has a pH over 2. Also disclosed is the use of the additive for preparing a material such as a cement, fly ash or slag with reduced chromium (VI) content; and a process for preparing the additive.