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Application of bio-dyes, especially plant-based, is becoming increasingly popular in many industries such as textiles, food and pharmaceuticals. This trend could be explained by the ecological and durable nature of these compounds. The current paper aimed to investigate the microwave-assisted isolation of Alkannin dye from Alkanna tinctoria followed by the dyeing of bio-mordanted silk. For the purpose, acid solubilized, water solubilized, and acid-methanol solubilized extracts were obtained. Both respective extracts and silk fabrics were microwave irradiated for 2, 4 and 6 min. To ensure a green and clean dyeing process, bio-mordants were used. It is observed that acid solubilized extract applied at 55 °C for 55 min having 7 g/100 mL of NaCl salt as the exhausting agent has given extraordinary higher color strength (K/S) onto Microwave treatment (MW) treated silk fabric. Colorfastness tests using ISO-recommended requirements found that bio-mordants outperformed chemical mordants in terms of color depth and fastness. According to this study, it was proven that MW improved the dyeing performance of Alkannin in an acid-solubilized medium, where as in addition to the application of bio-mordants in comparison with sustainable chemical mordants have improved color characteristics of silk fabric dyed with Alkanna tinctoria extract. [Display omitted] • The microwave-assisted extraction of Alkannin dye was investigated. • Bio-mordanting were used as a replace of metal mordant. • Bio-dyeing of silk shown excellent fastness properties. • Alkanna tinctoria based Alkannin dye can be an alternative of synthetic dyes. [ABSTRACT FROM AUTHOR]

Natural dye's poor affinity for cotton and poor fastness properties still hinder its applications in the textile industry. In this study, a doubled-layered chitosan coating was cured on cotton fabric to serve as bio-mordant and form a protective layer on it. Under the optimal treatment conditions, the maximum q e (adsorption amount) of the natural dye sodium copper chlorophyllin (SCC) calculated from the Langmuir isothermal model was raised from 4.5 g/kg to 19.8 g/kg. The dye uptake of the treated fabric was improved from 22.7% to 96.4% at 1% o.w.f. dye concentration. By a second chitosan layer cured on the dyed fabric via the cross-linking method, the wash fastness of the cotton fabric dyed with SCC can be improved from 3 to 5 (ISO 105 C-06). The natural source of the biopolymer material, chitosan, and its ability to biodegrade at end of life met with the initial objective of green manufacturing in applying natural dyes and natural materials to the textile industry.