Natural dyes extracted from Cassia fistula and onion peels are used to dye wool that is pretreated with chitosan by using tannic acid as a mordant. The effect of the mordant concentration on the color strength (K/S) is discussed. The results obtained indicated that K/S increases after treatment with chitosan. It is also noticed that K/S increases with an increasing concentration of chitosan. K/S also increases with an increase of mordant concentration until 4% and then decreases. The effect of the dye bath pH, dyeing temperature and dyeing time are also studied. The K/S and dye uptake exhibit high values. Good fastness properties of the dyed fabric are achieved. The antimicrobial activity of chitosan-treated wool fabric is tested in accordance to diffusion agents. Test organisms, such as Escherichia coli, Bacillus subitilus Pseudomons aeruginosa and Staphylococcus aureus are used and the results indicate that the samples treated with a lower concentration of chitosan exhibit a smaller inhibition zone.

W OOL fibers pretreated with chitosan and nano-chitosan and dyed with saffron red and yellow mixture as natural dye by using microwave heating method. The effect of chitosan and nano chitosan concentrations on color strength (K/S) was measured. The results indicated that, wool fibers pretreated with chitosan and nano chitosan recorded higher color strength than the untreated fibers. Fastness properties and the color yield of the dye on wool fibers were evaluated. The results indicated that color fastness to rubbing, washing and perspiration of all dyed wool fibers are excellent to good. The morphologies structure of the untreated and pretreated wool fibers were examined by scanning electron microscopy (SEM). The untreated wool fibers have a rough surface. The pretreated wool fibers were swelling compared to the untreated fibers. The diameter of the fibers increased and has smooth and even surfaces. The covering of the surface by bulk chitosan or nano-chitosan particles leads to the improvement in tensile strength and elongation of pretreated wool fibers. The antimicrobial activity with some species of bacteria and fungi were tested. The reduction percent for treated fibers were higher than the untreated fibers it reaches to 87% for Aspergillus Niger. The results obtained indicated that, the reduction percent of bacteria and fungi for fibers treated with nano chitosan was higher than chitosan it gave values from 75-87%

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