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Title: Alternatives to Sulfide Dehairing: Use of Oxidative Agents

Author
item Marmer, William
item Dudley, Robert

Submitted to: American Leather Chemists Association Meeting
Publication Type: Proceedings
Publication Acceptance Date: 5/15/2007
Publication Date: 6/20/2007
Citation: Marmer, W.N., Dudley, R.L. 2007. Alternatives to Sulfide Dehairing: Use of Oxidative Agents. In: Proceedings of International Union of Leather Technologists and Chemists Societies and American Leather Chemists Association Conference, June 20-24, 2007, Washington, D.C. 2007 CDROM.

Interpretive Summary:

Technical Abstract: The dehairing of cattle hides with sodium sulfate generates large quantities of waste that are of environmental concern as they have a large biological and chemical oxygen demand. Additionally, sodium sulfide is a potential workplace hazard. We had worked with industry to develop a rapid dehairing process for application in the abattoir; that process used concentrated sodium sulfide as the depilatory. The hazards of using sodium sulfide are possibly more so in the abattoir, since the agent is applied by spraying. More recently, therefore, we developed a sulfide-free, oxidative process for such rapid dehairing. We screened several oxidative systems for their effectiveness and chose a system composed of alkaline hydrogen peroxide and potassium cyanate. Some of the oxidative chemicals that we rejected because they did not dehair a hide in less than six minutes were suitable for use in the tannery as depilatories. Sodium perborate, for example, would reduce both the amount of solid and liquid wastes in the tannery waste stream. The byproduct of perborate dehairing, however, is borate, which may accelerate the degradation of wooden dehairing drums. In the paper cited for the Lollar Award (JALCA 100:419-431, 2005), we reported the results of a study that used sodium percarbonate as the dehairing agent for use in the beamhouse. The dehairing conditions were similar to the conditions developed for sodium perborate, but the byproduct is benign sodium carbonate. Although oxidatively dehaired hides exhibit a slight resistance to acid dye uptake, leather produced from percarbonate hides in all other studied aspects--shrinkage temperature, chromium uptake, elongation at break, and toughness--was comparable to leather produced from sulfide-dehaired hides. As for the peroxide/cyanate system, we will present preliminary results on its application in the beamhouse.