Extraction of Natural Indigo Dye From Indigofera Arrecta and its Application on Cotton Fabrics

Ukanah S.P.*1., Salisu Z.M.1, Shittu U.M.1, Gadimoh S.1,2, Joseph O. Odey3, Suleiman M.A.1, Gero M.1, Sulaiman
I.A.1, Umar I.S.1, Oddy-Obi I.C.1, Ilyasu A1. and Daniel D1.


1Department of Textile Technology, National Research Institute for Chemical Technology, Zaria, Nigeria.
2Department of Textile Technology, College of Science and Technology, Kaduna Polytechnic, Kaduna, Nigeria.
3Department of Pure and Applied Chemistry, Faculty of Physical Sciences, University of Calabar, Calabar, Nigeria.

*Corresponding author’s Email: pendo4success@gmail.com, doi.org/10.55639/607.02010091


ABSTRACT

Indigo dye is an historically important natural pigment that is traditionally obtained from plants of the Indigofera genus. In this study, indigo dye was extracted from Indigofera arrecta leaves via enzymatic hydrolysis and followed by alkaline treatment to release indigotin which is the principal chromophore. The extraction yielded approximately 0.236 wt % crude indigo based on fresh leaf mass as determined from a single extraction experiment. The dye was purified and characterized using UV–visible and FTIR spectroscopy to confirm the presence and structural integrity of indigotin. The dye exhibited a maximum absorption wavelength at 617 nm and was applied on cotton fabric through a conventional vat dyeing technique. Its dyeing performance was assessed based on dye uptake and colour fastness properties, including resistance to washing, rubbing, and light exposure. The wash fastness showed ratings between 4 and 5 for both colour change and staining of undyed adjacent fabric. Rubbing fastness results indicated ratings of 3–4 under wet conditions and 4 under dry conditions, while light fastness showed a rating of 6 on the blue wool scale. These results demonstrate that Indigofera arrecta is a viable alternative source of natural indigo, with promising dyeing performance and potential for sustainable textile applications.

Keywords:
Indigofera arrecta,
Enzymatic hydrolysis,
Indigotin,
Vat dyeing,
Chromophore.

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