NEW AND EFFICIENT PROCESSES FOR MAKING QUALITY LEATHER
Location: Eastern Regional Research Center
Title: RAPID OXIDATIVE DEHAIRING WITH MAGNESIUM PEROXIDE AND POTASSIUM PEROXYMONOSULFATE
Submitted to: Journal of American Leather Chemists Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 30, 2006
Publication Date: September 1, 2006
Citation: Gehring, A.G., Dudley, R.L., Mazenko, C.E., Marmer, W.N. 2006. Rapid oxidative dehairing with magnesium peroxide and potassium peroxymonosulfate. Journal of American Leather Chemists Association. 101(9):324-329.
Interpretive Summary: Tanners desire a safer and more environmentally sound means for the removal of hair from animal hides as an integral process in the production of leather. Meat packers desire the elimination of potential cross-contamination of hair-borne bacteria from hide to meat during slaughter. We have successfully demonstrated that several, relatively benign chemicals may be substituted for the traditionally used dehairing chemical, sodium sulfide, to not only remove hair from cattle hides, but to do so rapidly, thus finding potential for practical application in meat packing plants. Of the chemicals presented in this work, the ones that yielded the best rapid dehairing were alkaline magnesium peroxide and alkaline potassium peroxymonosulfate, as studied in 8 and 7 min reactions, respectively. Rapid dehairing, besides being a potential intervention strategy in the slaughterhouse against contamination of meat by pathogenic bacteria, allows for early grading of hides for quality and reduction in the amount of chemicals used for processing hides into leather by downstream tanneries.
Sodium sulfide is largely used to remove hair from animal hides during tanning operations. However, alternatives to sodium sulfide are desired because sodium sulfide is an environmental pollutant that is quickly converted to highly toxic hydrogen sulfide gas if accidentally exposed to acid. In past research, we have demonstrated that either alkaline calcium peroxide or alkaline hydrogen peroxide may be used as an effective substitute for concentrated sodium sulfide for rapid unhairing. More recently, we demonstrated the effectiveness of alkaline hydrogen peroxide with potassium cyanate. Here we similarly present alternative oxidative unhairing reagents/conditions-magnesium peroxide and potassium peroxymonosulfate, which may also find application in either the packing plant or beamhouse. As observed with previously reported rapid dehairing, dehairing often is not thorough, leaving a very short stubble. However, residual hair was readily removed with a sodium sulfide hairburn, indicating that hair stubble was not immunized by the oxidative treatment. Dehairing reaction conditions that rapidly removed 80% or greater of from cattle hide pieces were observed for magnesium peroxide (5%, 15% NaOH, 200% float, 45 deg C, 8 min, hairburn process), and potassium peroxymonosulfate (5%, 15% NaOH, 200% float, 45 deg C, 7 min, hairburn process). Leather produced from matched side pieces that were subjected to these oxidative dehairing treatments was determined to take up less chromium, yet was tougher than leather produced using conventional hairburn with sodium sulfide. Other physical testing results are also reported.