Avaliação da utilização de tanino vegetal no processo de curtimento de peles ovinas

Abstract

The tanning of sheepskins to turn it into leather is a very old process that has been improved with time. Currently, the Tanning Industries are seeking for sustainable alternatives for the treatment of leather in order to reduce the big generation of toxic wastes. The most dangerous raw material used in tanning is the trivalent chrome. This metal has the capability of removing organic compounds from the skin turning it in a stable and not rotten material, also not allowing its degradation to finally turning it into leather. The chrome is a very harmful metal to health and it can cause cancer in prolong contact with human skin or with the respiratory tract. It is also accumulative in rivers and grounds gradually generating pollution. The Industry facility target of this study works with the tanning of sheepskins to produce Wool Rolls. The tannery is the sector where the employs have more contact with dangerous materials so the substitution of the chrome as a less aggressive input is one of alternatives to reduce the risks of this sector. The vegetable tannin has been studied for the substitution of chrome in tanneries and it can be found in tree barks to perform the tanning through hydrophobic interactions and hydrogen bounds between phenolic groupings and layers of skin generating precipitated complexes. The tannin can perform tanning as good as the chrome but the tests made in Industry’s tannery showed the need of some changes in the process. For being very astringents, the tanning of vegetable tannin was performed with NaCl and mixed with acids to ease the diffusion of this material into the skin. At the end of the process, the final product showed the same characteristics of the tanning with chrome, indicated that the substitution in the production lines is viable.