Abstract:
This study was undertaken to utilize Taleh bark (Acacia Seyal Bark ) as a retanning material for production of upper and garment leathers. The Talh bark was collected from Gezera area and analysed for tannins, nontannins and solubles. The tannins content of Taleh bark was found to be20.4% and therefore it was promising and would successfully be used as retanning and tanning materials.
The Taleh bark was crushed into small particles and leached at various conditions of temperature, solvent : solid ratio, degree of mixing and time of extraction.
A two - level factorial experiments were designed and the level of the above factors were determined according to the statistical analysis.
It was found that a solvent solid ratio of 6:1, speed of agitation of 250 rpm, temperature of 30Ċ and time 2 hours were the optimum conditions. The extract produced was concentrated in triple – effect evaporator which was designed here in this work with the following dimensions : Tube outside diameter = 0.0254m, Tube inside diameter = 0.0186m, Tube length = 7.0m, Heating surface area = 70m2 , Number of tubes = 125tubes, Pitch = 0.138m, Tube bundle diameter = 0.358m and Shell diameter = 0.448 and steam economy of 4.3.
The thick liquor from the evaporator was spray –dried and the powder that produced was analysed for tannins content which was found to be 36.2%. The powder was used for retannag of upper and garment leather. The physical properties were determined and compared quite well with the standard specifications, the chemical analysis was in agreement with chemical standard.
In conclusion it is clear that Sudan can produce tannins extract from Taleh bark which can be used for pretannage, tannage and retannage. It is recommended that the Taleh bark and similar acacia seyal can be analysed and leached to give tannins powder extract to replace imported Mimosa extract.
