Abstract
An attempt was made to extract natural colourant from the bark of N. papaeverifera. The optimisation of the extraction procedure was evaluated using various solvents. The optimal colourant extraction was observed with acetone as solvent at constant temperature of 70 °C for 1 h. The main extracted colourant compound was isolated using column chromatography and characterised by ultraviolet-visible spectrophotometer, mass spectrometry, proton and 13C nuclear magnetic resonance spectrometry and Fourier transform infrared spectroscopy. The dyeing and durability of the colourant extract were evaluated. This low-cost biomass was obtained from a timber industry and its extract used to dye cotton and nylon 6,6 fabrics with only small amounts (6% and 4%) of metallic mordants, namely, copper(II) sulfate and stannous chloride. Dyed cotton and nylon were analysed for their K/S, CIE L*, a*, b*, c*, h* values and the colour fastness properties to light, crocking (rubbing) and washing. The UV-visible spectral result suggest the presence of such chromophores as C=O and –C=C–. The broad FTIR result at 3596 cm-1 is indicating a carbonyl group, the 13C NMR spectrum showed absorption at 206 ppm while the proton NMR gave absorption at 4.37 to 5.24 ppm suggesting –OH protons. Colour shades of brown were obtained. Significant differences in colour depth were observed depending on the mordant type. Copper(II) sulfate was found to produce the most significant colour changes, the deepest brownish colour, and the best light fastness and wash fastness values. The colourant extract itself (without mordant) had a light fastness of 3 (fair) on cotton fabric and 3/4(good) on nylon 6,6 fabric. In general, colour fastness to light was good (grade 5 for cotton and grade 4/5 to 5 for nylon) colour fastness to washing was very good (grade 4 to 4/5 for cotton and grade 3/4 to 4 for nylon) and colour fastness to rubbing was very good (grade 3/4 to 5). KEY WORDS: Natural colourant, Optimised extraction, Mordanting, Percentage of dye absorbed, Fastness Bull. Chem. Soc. Ethiop. 2019, 33(3), 415-424. DOI: https://dx.doi.org/10.4314/bcse.v33i3.3
Highlights
Researchers have found out that some synthetic dyes are toxic and during the process of their manufacture, large amounts of chemical wastes are produced [1,2,3]
It was observed that the yield of the natural dye using acetone alone as solvent was higher compared to those obtained using other solvents or water mixed with other additives
The results indicate that adding the sequence of the salt mordants to the dyeing bath could affect the colour appearance of the dyed cotton and nylon fabrics
Summary
Researchers have found out that some synthetic dyes are toxic and during the process of their manufacture, large amounts of chemical wastes are produced [1,2,3]. These processes discharge vast amounts of unsafe synthetic colourants into the environment as demands for coloured textiles increase because of their aesthetic, decorative and utilitarian applications. The world has become aware of the environmental consequences of many of the synthetic colourants. This has led to an increase in the demand for natural colourants by consumers. Despite the availability of these natural resources, their identification and scientific study have not been fully harnessed and documented
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
