Dhara Shukla

Natural Dyeing with Black Carrot: New Source for Newer Shades on Silk

Silk dyeing with black carrot or Daucus carota has been attempted for the first time, giving good shades on silk. The colorant responsible for shades of green is primarily anthocyanins, which are more stable over a wider pH range than anthocyanins from other vegetable sources, making it ideal for textile dyeing. Premordanted with metal salts the dyed silk has shown remarkable CIE La*b* values and fastness properties. The K/S of dyed silk swatches increased in the order of reactivity –FeSO4 > SnCl2 > SnCl4 > Alum > CuSO4 > K2Cr2O7. Black carrot can be a potential dyeing source for natural dyeing.

Role of Trichoderma Species in Bioremediation Process: Biosorption Studies on Hexavalent Chromium

Nonpathogenic fungal species can be powerful tools to remediate excessively polluted water. The tannery effluent carrying hazardous hexavalent chromium species due to the oxidation of trivalent chromium (Cr(III)) species was found to pollute the soil and the ground water of an area where a large number of tanneries are located. The phyto-remediation of Cr(VI) was studied with the help of a fungal species. Biosorption of the chromium ion Cr(VI) onto the cell surface of Trichoderma species in aerobic condition was investigated. Batch experiments were conducted with various initial concentrations of chromium ions to obtain the sorption capacity and isotherms. The results obtained at pH 5.5 of chromium solution were 97.39% reduction by non pathogenic species of Trichoderma. It was found that the sorption isotherms of fungi for Cr(VI) appeared to fit Freundlich models. The results of Fourier Transform Infrared Spectroscopy (FT-IR) analysis suggested that the chromium binding sites on the fungal cell surface were most likely carboxyl and amine groups. The fungal surfaces showed efficient biosorption for chromium in Cr6+ oxidation state. Best results for sorption were obtained at 5.5–5.8 pH, at low or high pH values, Cr(VI) uptake was significantly reduced.Abstract Nonpathogenic fungal species can be powerful tools to remediate excessively polluted water. The tannery effluent carrying hazardous hexavalent chromium species due to the oxidation of trivalent chromium (Cr(III)) species was found to pollute the soil and the ground water of an area where a large number of tanneries are located. The phyto-remediation of Cr(VI) was studied with the help of a fungal species. Biosorption of the chromium ion Cr(VI) onto the cell surface of Trichoderma species in aerobic condition was investigated. Batch experiments were conducted with various initial concentrations of chromium ions to obtain the sorption capacity and isotherms. The results obtained at pH 5.5 of chromium solution were 97.39% reduction by non pathogenic species of Trichoderma. It was found that the sorption isotherms of fungi for Cr(VI) appeared to fit Freundlich models. The results of Fourier Transform Infrared Spectroscopy (FT-IR) analysis suggested that the chromium binding sites on the fungal cell surface were most likely carboxyl and amine groups. The fungal surfaces showed efficient biosorption for chromium in Cr6+ oxidation state. Best results for sorption were obtained at 5.5–5.8 pH, at low or high pH values, Cr(VI) uptake was significantly reduced.

Innovative silk dyeing using enzyme and Rubia cordifolia extract at room temperature

Purpose Natural dyes are mostly used for dyeing of natural fibre textiles to improve their eco-friendly features. For successful commercial use of natural dyes, the appropriate and standardized dyeing techniques need to be adopted. Appropriate scientific techniques or procedures need to be derived from scientific studies on dyeing methods, dyeing process variables, dyeing kinetics and compatibility of selective natural dyes with minimal use of hazardous chemicals. Design/methodology/approach In the present study, different enzymes (protease, amylase, xylanase, pectinase, phytase) were used efficiently with Rubia dye by using simultaneous and two-step processes; both the processes were developed with an aim for conservation of time and energy, for the ease of industrial use. The highlights of the study are twofold: eco-friendly natural dyeing by using enzyme replacing metal mordant and room temperature dyeing, which is a completely new concept. Findings Experiments showed that enzymatic treatment can give good colour strength to silk fabric using Rubia as a dye source and has good potential for commercial dyeing. It is a non-toxic dye. Use of enzymes were a deliberate attempt to avoid metal mordanting in silk dyeing, as it would make textile dyeing eco-friendlier. The order of reactivity of enzymes in one-step process was found to be protease > phytase > xylanase > amylase > pectinase. Similarly, for two-step dyeing process, the order of reactivity of enzymes observed was protease > amylase > xylanase = pectinase > phytase. Protease enzyme was the best option in both the cases. Overall, it can be concluded that in the case of enzymatic treatment, the two-step process was better in terms of larger K/S values, colour coordinate values and dye adherence. Research limitations/implications A new domain of room temperature dyeing technique has been introduced. Originality/value In the present study, different enzymes (protease, amylase, xylanase, pectinase, phytase) were used efficiently with Rubia dye by using simultaneous and two-step processes; both the processes were developed with an aim for conservation of time and energy, for the ease of industrial use. The highlights of the research are twofold: eco-friendly natural dyeing by using enzyme replacing metal mordant and room temperature dyeing, which is a completely new concept. Overall, the ease of use for industrial application. Rubia dye from Sri Lanka has been used in conjunction with different enzymes to show that metal mordanting can be easily replaced by the use of eco-friendly and biodegradable enzymes. The most attractive feature of this study is the low-temperature dyeing at 30-40°C. For any dyeing house, this process can be easily adapted on jigger, winch or even in continuous padding machine. Good fastness properties and dye adherence have been the other highlights of this study.

Curcuma Dye with Modified Treatment Using Chitosan for Superior Fastness

Curcuma dye could never gain popularity in natural dyeing as the intrinsic nature of the colorant Curcumin did not have the requisite adhering property towards natural fabrics such as silk and cotton, thereby making it very fugitive. In this paper attempts have been made to activate Curcumin molecule by complexation with chitosan (another natural linear polysaccharide). The binding took place at intrinsic pH (7–8) very effectively without any surfactant or enzyme. Dyeing with this new composite showed excellent wash and light fastnesses as compared to curcuma dye. The novelty of this dyeing process is the remarkable enhancement of wash and light fastnesses levels by 1.0–1.5 for silk and cotton fabric dyeing in just 1 hour at 40–45 °C. It is fast and energy conserving dyeing process. Three subsequent washing of the dyed samples showed very small change in CIE Lab.