The improved tandem oxidation sequence of starch with the aim of developing, e.g. degradable co-builders suitable for laundry formulations as an alternative to the currently used polyacrylates is described. The tandem oxidation of starch starts with sodium periodate treatment of granular starch followed by oxidation of the dialdehyde product with sodium chlorite to dicarboxy starch. It turns out that improving the periodate oxidation resulting in a more complete transformation of the glucose moiety into the dialdehyde product yields, after sodium chlorite oxidation, a dicarboxy starch with a calcium sequestering capacity of 3.3 mmol Ca2+ per gram of dicarboxy product. This is an improvement of about 25% compared with current literature data.
- Starch oxidation