| 摘要 |
A composition (I) for reducing hexavalent chromium (Cr(VI)) ions in cement (or cement-containing products) contains (A) 1-97 wt. % metallic reducing agent, based on ferrous (Fe(II)), stannous (Sn(II)) and/or antimonous (Sb(III)) ions, and (B) 0.5-90 wt. % organic reducing agent based on ascorbic acid, hydroxypropanedial and and/or reducing saccharides. A composition (I) for reducing hexavalent chromium (Cr(VI)) ions in cement (or cement-containing products) contains (A) 1-97 wt. % metallic reducing agent, consisting of or comprising one or more of ferrous (Fe(II)), stannous (Sn(II)) and antimonous (Sb(III)) ions and their salts and (B) 0.5-90 wt. % organic reducing agent consisting of or comprising one or more of (a) ascorbic acid, ascorbate and their derivatives, (b) hydroxypropanedial and its derivatives and/or (c) reducing saccharides. Independent claims are included for: (1) the use of (I) for the preparation of cement (or cement-containing products); (2) a method for reducing hexavalent chromium (Cr(VI)) ions in cement (or cement-containing products), involving mixing the cement or product (specifically before, during or after milling) with (I) in an amount such that concentration of Fe(II)), Sn(II) and/or Sb(III) ions (by weight based on the cement component) is at least 0.000002% (preferably at least 0.00002%) per ppm of Cr(VI) to be reduced; and (3) the use of the organic reducing agents (B) for potentiating the reductive power of the metallic reducing agents (A), specifically in the reduction of Cr(VI) ions in cement or cement-containing products. |
