RAPID OXIDATIVE DEHAIRING: RECYCLING OF THE DEHAIRING REAGENTS

Authors: Dudley, Robert; Marmer, William

Submitted to: American Leather Chemists Association Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/2004
Publication Date: 6/1/2004
Citation: Dudley, R.L., Marmer, W.N. 2004. Rapid oxidative dehairing: recycling of the dehairing reagents [abstract]. 100th Annual Meeting of the American Leather Chemists Association. Paper No. 18.

Interpretive Summary:

Technical Abstract: There is continuing interest by the packing industry in the use of rapid dehairing as a pathogen reduction step. Any such procedure must not compromise the quality of the resulting hides. We have been developing sulfide-free, oxidative processes for rapid dehairing. Recycling of the oxidative dehairing mixture is required for the protocol to be a commercially viable option. In lab-scale experiments using a peroxide/cyanate system, we successfully recycled our dehairing agent 5 to 7 times. A number of factors eventually affected the agent's efficacy. NaOH, KOCN, and H2O2 were consumed and solubilized protein began to interfere as a buffer, dropping the pH below 13 after 7 to 9 recycles. The hydrogen peroxide concentration dramatically dropped during the first three cycles of the dehairing solution and then remained at a constant but still effective concentration of 1-2 ppm. The protein concentration was dependent upon the length of the hair, but generally after three cycles the concentration was approximately 24 to 40 g/L. Removal of the insoluble hair (roughly 60% of the protein in the waste stream) did not affect the efficacy of the dehairing solution, but somewhat higher H2O2 concentrations (>10 ppm) could be maintained when the solids were removed.