- Title
- Optimising syzygium cordatum dye extraction and subsequent cotton dyeing incorporating organic electrolytes
- Creator
- Gamedze, Nombuso Faith
- Subject
- Dyes and dyeing -- Cotton Syzygium cordatum
- Date Issued
- 2017
- Date
- 2017
- Type
- Thesis
- Type
- Masters
- Type
- MSc
- Identifier
- http://hdl.handle.net/10948/19509
- Identifier
- vital:28888
- Description
- The present investigation was carried out to optimize the extraction of natural dye from Syzygium cordatum,bark trees and then to evaluate its use in the dyeing of cotton fabric incorporating organic electrolyte. The bark was collected from recently fallen trees and twigs pruned from old trees, since they have greater dye content than the younger trees, dried for two weeks, crushed with a hammer and ground into powder. Grinding of bark was done to ensure a uniform particle size with a large surface area to facilitate quick extraction. The relevant conditions for natural dye extraction using a methanol/water mixture were optimized by Response Surface Methodology (RSM), with the help of Design Expert Version 7.0. The central composite design (CCD) was applied to design experiments for the evaluation of the interactive effects of the three most important operating extracting variables namely, temperature, time and liquor volume on 25g bark powder. This approach decreased the required number of experiments, and the following optimized extraction conditions were derived; temperature 700C, time 51minutes and material-to-liquor ratio 1:16. Dye used for subsequent dyeing was extracted using the optimized conditions. To determine the best conditions for dyeing cotton fabric with the dye extract, dyeing was carried out in a rotating canister machine, using two different organic electrolytes, namely trisodium nitrilo triacetate (trisodium NTA) and dimethylformamide, as mordants. The use of organic electrolytes, as mordants, was to ensure eco-friendliness of the dyeing, and with a maximum concentration of 3g/L being used to reduce the effluent load. Three different mordanting techniques, namely simultaneous, pre-mordanting and post-mordanting were investigated so as to establish which is best. The impact of the two organic electrolyte mordants on certain physical properties of the cotton fabric was also determined. The dyeing of cotton with theSyzygium cordatum bark dye extract, in conjuction with an organic electrolyte, generally showed good results, with trisodium NTA superior to dimethylformamide as a mordant. An increase in trisodium NTA mordant concentration increased dye exhaustion and a dye exhaustion of 23.7% being achieved with 3g/L pre-mordanting. This is still relatively low, however, and the use of an exhausting agent needs to be explored. The fabric dyed with a mordant, exhibited good wash, rub and perspiration fastness, with trisodium NTA superior to dimethylformamide. The use of trisodium NTA increased the strength of the dyed fabric whereas the use of dimethylformamide decreased it. In general, pre- and simultaneous mordants were better than post-mordanting. It has been shown that the dyeing of cotton, using Syzygium cordatum bark dye extract, in conjuction with an organic electrolyte, particulary trisodium NTA, has potential and can be recommended for craft applications. Optimised conditions for dye extraction and cotton dyeing have been derived and which can be recommended for use by crafters in Swaziland.
- Format
- xiii, 120 leaves
- Format
- Publisher
- Nelson Mandela Metropolitan University
- Publisher
- Faculty of Science
- Language
- English
- Rights
- Nelson Mandela Metropolitan University
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NMU School of BioMolecular and Chemical Sciences
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