The aim of the thesis was to study the dyeing of natural cellulose fibres with the extract of an avocado seed, which is considered waste in food processing. Cotton (CO) and linen (LI) samples were used for dyeing. The samples were dyed at two different pH values (neutral and alkaline), using a dried avocado seed (first extraction) and its residue after the first extraction (second extraction). Deionized water was used to prepare dyebath with neutral pH, while the extract of wood ash was used as a medium for preparing the alkaline dyebath. The cotton and linen samples were dyed at room temperature, at a liquor to goods ratio of 40:1, in the time range from 15 to 120 minutes. The samples dyed in a neutral medium were later washed to evaluate durability to washing. Undyed and dyed samples were analysed for their colour and colour yield (CIELAB and K/S) and transmission in the UV area, with ultraviolet protection factor (UPF) calculated and the antioxidant activity (%) determined. Results show that longer dyeing time causes the samples to darken, increases the values of antioxidant activity and colour yield (K/S). Samples dyed in the alkaline medium were darker in colour and had more pronounced tones (higher CIE a* and CIE b* values) than samples dyed in neutral medium. Linen samples had better washing durability than cotton samples. Although the dye was removed from the washed linen samples and the CIELAB and K/S and UPF values decreased, the antioxidant activity values were not significantly reduced.
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