Natural dyes, obtained from plants, insects/animals, and minerals, are renewable and sustainable bioresource products with minimum environmental impact. However, there are still many issues to solve related to natural dyes; consequently, synthetic dyes are still wildly used. Natural dyes have a low affinity towards the substrate cotton, so a solution had to be found: mordants. Mordants can also be harmful to the environment, which is why bio-mordants are used. The mordant used in this paper is chitosan. Cotton is pre-mordanted using the pad dyeing method. By using the exhaustion method, the fabric was coloured with red Camellia sinensis (tea) extracts. The colour, absorption of polyphenols and tannins, and ultraviolet protection (UPF) were tested. A comparison study was carried out between the cotton fabric and the cotton padded with chitosan at two different concentrations. The results are impressive. Cotton pre-mordanted with chitosan can absorb more polyphenols and tannins than cotton itself, and the colour fastness and UPF, once the fabric is laundered, demonstrate there is some kind of bonding between the fibre, quitosan, and active compounds from tea. The UPF was also doubled by using chitosan and the reddish colour obtained by Camellia sinensis extracts were darker on the cotton fabric. The increase in UPF protection on mordanted fabrics is higher than the gap obtained by colour difference, which means there are active compounds that do not confer colour, but enhance UPF protection.

<div data-canvas-width="583.1287199999997">The last few years natural dyes rose in value. Some synthetics dyes are proven to be environmentally harmful and can cause negative effects. Due to the eco awareness the natural dyes were again wildly used. Tea extracts from the Camellia sinensis plant were used. Tea has a large range of phytoconstituents and some can be transferred onto the cotton fabric. The optimal time and temperature to obtain as many phytoconstituents as possible had to be established. The aim of this study was to optimize the extraction process from tea so as to apply the maximum concentration of phytoconstituents onto the textile fibers and improve the cotton functionalization (Ultra violet protection for example) once it is dyed with the extract. Results demonstrate time and temperature had a great influence on the optimization of the tea extracts. We could conclude that after 2 hours the most polyphenols, hydrolysable tannins and condensed tannins are obtained and increasing the time didn’t add any value. The temperature was a really important factor because the polyphenols derived around 70 °C so both the extraction temperature and dyeing treatment should be below 70 °C. Wastewater were characterized in order to determine the phytoconstituents were in the cotton fibres.</div>