Processing of collagenic residues. Isolation of gelatin by the action of peroxochromates

The experience of our research group with topics related to the dechroming process, based on the oxidation of the chromium(III) to chromium(VI) by per oxides in alkaline conditions, allowed us to know in-depth the reaction mec hanisms. The formation In situ of some peroxochromates (containing up to 2, 5 groups peroxo for each atom of chromium), unstable and with a great oxidi zing potential, is fundamental in the process of gelatin isolation. It has been demonstrated that the chromium-containing collagenic wastes that had b een previously dechromed by this method produce a gelatin with better yield , quality and in a much shorter treatment, compared with conventional metho ds described in the literature. The residual chrome content in the gelatin can be eliminated using tangencial ultrafiltration and reverse osmosis tech niques. Furthermore, the chromium (VI) is recovered by ion-exchange resins and can be re-used in tanneries. Finally, physico-chemical characteristics of the isolated gelatins were evaluated.