علوم - دكتوراة
Permanent URI for this collectionhttps://repository.neelain.edu.sd/handle/123456789/511
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Item Determination and Characterization of Tannin Material Extract From Three Common Acacia Species in Sudan(Al Neelain University, 2009) AYMAN AHMED AL-KHDIR ALI JACKNOONThis research is dealing with the analysis and comparative studies of tannins of three common Acacia species of Sudan. Since vegetab1e tannins are important for leather industry, A. nilotica and A. seyal samples were collected from Sunut forest in Khartoum State while A. tomentosa, samples were collected from the shmbata Forest. Bark samples From collections of the three acacia species ,were extracted with distilled water, 80% methanol and 70% acetone ;two sets of extraction were made, one by boiling, and the other by shaking the samples in the respective solvent for eight hours at room temperature. Although the amount of material extracted by these two procedures did not differ greatly , 70% acetone was a more efficient solvent than either water or 80% methanol. Qualitative analysis showed that the fruits (garad) contain tannins materials, flavinoid coumarins, and quantitative analysis showed that the fruits (pods) contain a higher percentage of tanning materials, that can be used commercially, barks contain XIII low tannin content compared with fruits. Also it was found that the unripe fruits give the highest percentage of the tannins content. Rotary system (with extraction changing in size of powder, rate of solvent to the fruits weight, and solvent temperatures), enabled access to extracts with high concentration when using crushed fruits, water at 70°C and ratio of (3:1) of water to fruits weight. Sodium fluoride and a mixture of oxalic acid and sodium sulphite showed high efficiency as antifungal reagents. With the mixture of acid - sulphite was found to be the best bleaching agent compared with sodium fluoride The amount of tannins present in the bulk samples was determined by folindenis method for total phenolic materials, followed by precipitation with hide-powder. The difference between the amount of phenolic materials present before and after addition of hide-powder represent the amount of tannins present. The extracts of the bark of A. nilotica A. seyal and A. tomentosa, contain (80.45% ,59.9% and 33.5%) tannins respectively. The amount of iron content of the extracts and samples of Acacia species was determined since the Iron hinders the process of retanning leather of Iron content was determined by atomic absorption spectrophotometry. The iron content of bark extracts of A nilotica, A tomentosa and A seyal is 0.0044%, 0.0040% and 0.0029% respectively. In contrast, the iron content of bark extract of the three species of Acacia had lower percentage compared to that of Mimosa (0.00475%), which is imported from Kenya. The tannins of a mixture of powder of Acacia nilotica and bark of the acacia seyal were identified by using thin layer chromatography (TLC), ultraviolet and infrared spectroscopy. Comparisons of the absorption spectra and TLC of the reference tannins and some phenolics with that of a mixture extracts revealed the presence of both condensed and hydrolysable tannins, since it consists of catechin, tannin and gallic acids. The leaching materials were powdered using spray drier. They exhabited excellent properties, when used for tannage of leather. Better physical and chemical properties of leather were achieved compared with leather tanned using mimosa powder.