Study of the dechroming of tanned leather wastes

Abstract

According to European legislation, it is not possible to dump any chromium-containing waste in Europe. The minimization of wastes is a key element in that strategy. It involves the application of clean technologies: low and non-waste technologies. The tanning industry generates substantial quantities of chromium-containing solid waste in the form of shavings and trimmings. The recycling and reuse of those wastes must be the primary target in optimizing processes of the leather industry. The problem is in a satisfying chromium separation from collagen fibers. Common hydrolysis processes-alkaline or acidic-give gelatins containing residual chromium (III). By using an oxidation agent (H2O2) before alkaline hydrolysis, in was demonstrated that chromium from chromium-containing leather wastes can be almost fully recovered by the previous oxidation of Cr(III) to Cr(VI). This chromium can be reused in the tanning process. That would represent an economic saving. The best result of the dechroming process was a gelatin hydrolyzate with only 1.11 in respect to the initial amount.

Keywords

• Leather wastes
• dechroming process
• oxidative hydrolysis
• gelatin