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Cotton fabrics were double pre-mordanted with natural potash alum and tannin-rich gallnut (Quercus infectoria), acting in combinations as dual-bio-mordants for dyeing it with tannin-rich catechu natural dye extract. This study confirmed that K-Alum and gallnut dual-bio-mordanting, followed by dyeing it with catechu extract, formed a bigger giant water-insoluble complex of [Cotton-Al-Gallo-tannins-Catechin] and produced an orangish brown colour shade on cotton. The said dual pre-mordanted cotton using overall 15% [K-alum+gallnut in 75:25 proportion], applied one by one in the sequence, was found to offer maximum colour strength (K/S 12.19 and average to good colour fastness to wash, UV–light, and rubbing, improving 1/2 to 1 grade. Finally, all the conditions of dyeing parameters were standardised for the said overall 15% (K-Alum+Gallnut in 75:25 ratio) dual-pre mordanted cotton fabrics for dyeing with catechu and the standardised dyeing conditions found are––30% concentration of catechu extract, pH 4.0 for dye bath, 1:20 MLR, 60 min time of dyeing and 70 °C temperature of dyeing and 5gpl salt concentration, to obtain maximum colour strength up to 12.19 with CV% of K/S within 5% indicating more uniform colour. Moreover, a good degree of bacterial reduction up to 80–85% and a reasonable degree of UV–resistant properties, UPF value up to 30 can be achieved, for such 30% catechu-dyed cotton after overall 15% K-alum and Gallnut (75:25) dual pre-mordanting. Further 10% aqueous extract of Eucalyptus leaves applied as a bio-finish by pad-dry-cure process do not alter the colour strength much, but bacterial reduction is improved up to 90–95% with UPF value improved up to 40. This work is thus considered useful for producing uniform, reproducible deep shades for such catechu dyed cotton fabric-based medical textiles for use in improving the wellness behaviour of human wearers.

Bleached cotton fabric was chemically modified (cationized)with natural amino acids extract obtained by acid hydrolysis (6N HCL) from soya bean seed waste, adding MgCl2 as an acid donor in the pad-dry-calendaring process to investigate the changes in textile properties and its dyeability with reactive dye in both a conventional alkaline dye bath and salt-free acidic dye bath. This modified cotton incorporates new functional groups producing - NH 3 + in acid bath to obtain cationized cotton, rendering it to eco-friendly salt-free reactive dyeing at acceptable shade depth without much sacrifice of other textile-related properties. Bi-functional high exhaustion-type reactive dye shows better dye uptake than mono-functional cold brand as well as hot brand reactive dye. Moreover, the application of a specific dye fixing agent further improves surface color depth (K/S) of the soya-modified cotton fabric. The study of surface morphology of said chemically modified cotton substrate indicates a higher degree of surface deposition, that is, more anchorage of soya extracted amino acids on cotton fabric. Chemical anchorage as per the reaction scheme postulated for such modifications is verified with Fourier transform infrared spectroscopy. Finally, it is revealed that cotton treated with soya extract provides a new route of eco-friendly salt-free reactive dyeing with high exhaustion-type reactive dyes showing much higher dye uptake than the control cotton fabric.

Jute fabric was treated with mixed natural amino acids obtained from waste soya bean seed extract for chemical modification of jute for its cataionization and to enhance its dyeability with anionic dyes (like direct, reactive and acid dye) as well enabling soya modified jute for salt free dyeing with anionic reactive dyes maintaining its eco-friendliness. Colour interaction parameters including surface colour strength were assessed and compared for both bleached and soya-modified jute fabric for reactive dyeing and compared with direct and acid dye. Improvement in K/S value (surface colour strength) was observed for soya-modified jute even in absence of salt applied in dye bath for reactive dyes as well as for direct and acid dyes. In addition, reactive dye also shows good dyeability even in acid bath in salt free conditions. Colour fastness to wash was evaluated for bleached and soya-modified jute fabric after dyeing with direct, acid and reactive dyes are reported. Treatment of jute with soya-extracted mixed natural amino acids showed anchoring of some amino/aldemine groups on jute cellulosic polymer evidenced from Fourier Transform Infra-Red (FTIR) Spectroscopy. This amino or aldemine group incorporation in bleached jute causes its cationization and hence when dyed in acid bath for reactive dye (instead of conventional alkali bath) showed dye uptake for reactive dyes. Study of surface morphology by Scanning Electron Microscopy (SEM) of said soya-modified jute as compared to bleached jute was studied and reported.

Bleached cotton muslin fabric with or without pre-oxidized with NaIO4 (oxy-cotton) was chemically modified with glycine (amino acid) by pad dry calendar process to investigate the changes in textile properties and its dyeability with reactive dye. This glycine modified cotton incorporates new functional groups producing –NH3+ or –C=NH+ -ion (cationic groups) in acid bath to obtain cationized cotton making it amenable to a newer route of salt free reactive dyeing in acid bath. In the present work the process variables of reactive dyeing in the salt free acid bath for dyeing of amine (glycine) modified cationized cotton were studied and optimized. The present study also includes thorough investigation of changes in important textile related properties and dyeability with reactive dye after such chemical modifications. Between oxidized and unoxidized cotton muslin fabric, unoxidized cotton fabric shows better reactive dye uptake in both conventional alkaline bath dyeing and nonconventional salt free acid bath dyeing particularly for high exhaustion class of reactive dye with acceptable level of colour fastness and overall balance of other textile related properties. Moreover, application of dye fixing agent further improves surface colour depth (K/S) of the glycine treated cotton fabric for HE brand of reactive dyes. Corresponding reaction mechanisms for such modifications were supported by FTIR spectroscopy. Finally unoxidized cotton and pre-oxidized cotton further treated with glycine (amino acid) provide a new route of acid bath salt free reactive dyeing showing much higher dye uptake and higher degree of surface cover with amino acid residue anchored to modified cotton.