POTENTIAL OF VEGETABLE TANNING MATERIALS AND BASIC ALUMINUM SULPHATE IN SUDANESE LEATHER INDUSTRY

Ecological pressures on chromium have now forced the leather industry to lookfor possible alternatives. A vegetable- aluminum combination tannage has beenstudied, with special attention being given to intended final product. Aluminum ismineral tanning agents that are widely used to stabilize collagens in the leatherindustry. In this study, the crosslinking of vegetable and aluminum, withcollagens, have been explored. This kind of chrome free tannage give us leatherswith shrinkage temperature around 125oC, elongation at break 65.6%, tensilestrength 38 N/mm2, and tear strength 98 N/mm. The chemical properties of thecombination tanned leathers are found to be quite normal. Among thecombination system evaluated, a vegetable pretannage followed by retannage withbasic aluminum sulphate was found to produce stronger leather with the durablecharacteristics. In contrast, pre-tanning with aluminum possibly tightens thecollagen fiber network, preventing high molecular weight vegetable tannins frominteracting with collagen fibres. Optimal results were obtained when 10% (w/w)vegetable tannins (garad) and 2% Aluminum sulphate was used.