Debasish Das

Bio: Debasish Das is an academic researcher from National Institute of Fashion Technology. The author has contributed to research in topics: Dyeing & Colour fastness. The author has an hindex of 4, co-authored 4 publications receiving 72 citations.

Colouration of wool and silk with Rheum emodi

Abstract: Silk and wool fabrics have been dyed with colourant extracted from Rheum emodi in the absence and presence of magnesium sulphate, aluminium sulphate and ferrous sulphate mordants for producing shades of different colours, ranging from yellow to olive green Colouring component of Rheum emodi has close resemblance with a typical anthraquinonoid type disperse dye; the uptake of such colouring component by the protein fibres remains unaffected within a wide pH range of 4 – 8 Colour uptake, rate of dyeing and affinity of colour are found to be more for silk than that for wool under all the conditions studied The dyeing mechanism corresponds to the partition mechanism, confirming that this anthraquinonoidbased colourant is adsorbed by silk and wool fibres as a disperse dye and the dyeing process is endothermic The use of ferrous sulphate and aluminium sulphate produces significant improvement in depth of shade, when both the substrates are treated with such salts prior to application of the colourant Coloured protein fibres, in general, show a common light fastness and wash fastness ratings of 4 and 3 respectively Ferrous sulphate, however, improves the colour fastness properties and colour retention on washing of both wool and silk fabrics further

Dyeing of wool and silk with Punica granatum

Abstract: The application of dye obtained from Pllllica grw/{/tl/lll fruit rind on wool and si lk fabric i n the presence and absence of environment-friendly Illordanting agents has been studied. The dyeing of s i lk and wool with pomegranate solution is found to be effecti vely accomplished at pH 4.0. Preand post-mordanting employi ng ferrous sulphate and aluminium sulphate improve the colour uptake, l ight fastness and colour retention on repeated washi ng. The use of such mordants, however. does not improve wash fastness property of dyed substrates.

Concurrent dyeing and finishing of cotton with natural colour and citric acid in the presence of NaH2PO4 as catalyst under thermal treatment

Abstract: Cotton fabric was simultaneously modified and dyed with citric acid and Camellia sinensis, and citric acid and Punica granatum in the presence of sodium di‐hydrogen phosphate (NaH2PO4) as the catalyst using a pad–dry–cure technique. Treatment with 10% citric acid, 15% NaH2PO4 and any of the above‐mentioned dyes at 100% wet pick‐up, followed by drying at 95°C for 5 min and curing of the dried fabric at 140°C for 5 min produced most balanced improvements in respect of the depth of shade, wrinkle recovery and colour fastness to light, wash and rubbing with retention of more than 70% of the original strength. Infrared analysis of the dyed cotton fabric indicated that the treatment of cotton with citric acid and either Camellia sinensis or Punica granatum under the influence of an esterification catalyst led to the esterification of carboxyl groups of citric acid and of hydroxyl groups of cotton cellulose and with that of both the dyes. The said process also led to some degree of cross‐linking of polymeric cha...

Modification of cotton fabric with acrylamide in the presence of K2S2O8 for improving dyeability of natural dyes

Abstract: Cotton fabrics were modified using acrylamide as the aminating agent in the presence of potassium peroxodisulphate (K2S2O8) as a free radical polymerisation catalyst using a pad–dry–cure technique in order to improve the dyeability of cotton fabrics with natural dyes. Pre‐soaking of bleached cotton fabric with 5 g l−1 K2S2O8 and subsequent application of 10 g l−1 acrylamide monomer on the pre‐soaked cotton fabric, followed by drying of the padded fabric at 95°C for 5 min and curing of the dried fabric at 140°C for 5 min, produced most balanced improvements in dye uptake, tensile strength and wrinkle recovery angle for optimum retention of flexibility of the dyed substrates when pre‐treated cotton fabrics were dyed with Camellia sinensis and Punica granatum. Application of ferrous sulphate on pre‐treated cotton fabric following a pre‐salt application method and subsequently dyeing with Camellia sinensis and Punica granatum improved the depth of shade and all‐round colour fastness properties further. Infrar...

Natural Colorants in the Presence of Anchors So-Called Mordants as Promising Coloring and Antimicrobial Agents for Textile Materials

Abstract: In recent years there has been a phenomenal increase in the use of natural colorants in a variety of areas. They exhibit high biodegradability, low toxicity, and green chemistry and have potential to greatly impact the textile dyeing and finishing industry. Natural colorants from plant sources have been recently discovered as novel agents in imparting multifunctional properties to textiles such as antimicrobial, insect repellent, deodorizing, and UV-protective. Among all textile surface modifications, antimicrobial finishing has become a very promising, high growth research area due to their potential to provide quality and safety benefits to different kinds of textile materials. The use of natural colorants offers promise in developing antimicrobial textiles for aesthetic, hygienic, and medical applications owing to the presence of potent highly active agents such as tannins, flavonoids, quinines carotenoids, and alkaloids in their extracts. This article presents a concise account of the state-of-the art...

Phytochemical biopesticides: some recent developments

Abstract: Synthetic pesticides in general, are highly toxic, persistent and their harmful residues contaminate crops, food commodities and pollute soils and groundwater. They adversely affect non-target organisms like pollinators, fish, birds, animals, and their excessive use results in increased resistance in pests. Phytochemical biopesticides on the other hand are less toxic, least persistent, environment friendly and safe to humans and non target organisms. Several phytochemical biopesticides like azadirachtin, nicotine, pyrethrins, rotenone, veratrum, annonins, rocaglamides, isobutylamides etc. have been successfully commercilalized in the past. In this review pesticidal products based on Madhuca indica (Mahua), Sapindus mukorossi (soapnut), Curcuma longa (turmeric), Pongamia glabra (karanja), Eupatorium adenophorum (Crofton weed), Tagetes erecta (marigold), Rheum emodi (Himalayan Rhubarb) and essential oil bearing plants have been discussed. Natural insecticide synergists derived from Anethum sowa and their semisynthetic derivatives have been used to prolong efficacy and counter resistance in insect pests.