Abstract:

The study aims at optimizing the uptake of tannins obtained from Piliostigma thonningii by goat skin, using a central composite design. The study was carried out using the central composite design of experiment version 10.0.3.1 which consists of four factors. Bark of Piliostigma thonningii were collected freshly. The barks were dried in an electric oven at a temperature, of 100-105oC and later crushed to powder, to increase the surface area. The samples of goat skin were obtained and were then divided vertically through the backbone into two equal halves, and subjected to the standard procedure of the leather tanning processes. The samples of skin pieces obtained were tanned using the standard procedure of leather tanning. The plant samples were subjected to four experimental conditions, concentration (%), pH, particle size (mm), and time (min). The result indicates that the optimization conditions required for the uptake of tannins by the sample (goat skin) were 20% of plant material, pH of 4.81, 1.988 mm of particle size, and 50 min of time. The optimum responses of the leather produced were 77°C (shrinkage temperature), 27.934 N/mm2 (tensile strength), 13.009 mm (lastomer distention), and 0.293% (water vapor permeability) obtained respectively. Control of these parameters resulted in producing the most stable and flexible leather, which will release fewer contaminants into the environment. Based on the result obtained in the study, Piliostigma thonningii bark can be used as one of the vegetable tanning materials.