FIELD: chemistry.
SUBSTANCE: invention discloses methods based on achieving in a chromium plating electrolyte, pH for formation of iron (III) hydroxide and pH for precipitation of chromates and hydroxochromates of iron (III) and copper (II) in the interval of 1.5-4.0. These conditions are achieved by adding to the chromium plating electrolyte or to its diluted solutions such reagents as aqueous solutions of hydrazine, hydroxyamine or hydrogen peroxide, as well as due to hydrolysis at temperature 70-120°C in a strongly diluted chromium plating electrolyte which is contaminated with iron and copper cations.
EFFECT: low concentration of harmful impurities.
3 cl, 2 ex
