Sorption Characteristics of Indigo Carmine as a Blue Colorant for Use in One-bath Natural Dyeing

Abstract

Indigo carmine can be used as model for a blue natural colorant for wool and hair dyeing in a one-bath procedure. The sorption and dyeing properties of indigo carmine on wool are studied as a prerequisite for the successful application in combination with natural dye. To evaluate the suitable conditions for the dyeing process, different pH, dye concentrations and temperatures were studied. The dyeing and sorption characteristics on wool were determined on the basis of spectrophotometry and color measurement. Both high dye sorption and color strength were obtained when dyeing at elevated temperature, e.g. 80°C, and lower pH, e.g. pH 3. However, there is significant potential to apply the dyestuff also at temperatures in the range of 40—60°C and pH values of 4—5. Depending on the dyebath pH the sorption isotherms follow the Langmuir- or Freundlich-type isotherm. At pH 3 and 4 Langmuir isotherms are observed, while at pH 5, 6 and 7 sorption on wool follows the Freundlich isotherm behavior. From the dyeing isotherms the standard affinity (Δµ) of the dyeing step was determined. At pH 3 the heat of dyeing (ΔH) and entropy of dyeing (ΔS) were calculated as 40.22 kJ mol -1 and 0.19 kJ mol-1 K -1, respectively.

Single box dyeing of denim yarns under nitrogen protection with high indigo concentration

“…When the dyeing of denim yarn has reached saturation, attaching more indigo will not improve the K / S value or dyeing uptake. 28 The effect of Na 2 S 2 O 4 concentration on the dyeing performances of denim yarns dyed using the cleaner dyeing process is shown in Figure 2(c). The dye bath was composed of 15 g/L indigo and 10 g/L NaOH.…”

“…When the dyeing of denim yarn has reached saturation, attaching more indigo will not improve the K/S value or dyeing uptake. 28 The effect of Na 2 S 2 O 4 concentration on the dyeing performances of denim yarns dyed using the cleaner dyeing process is shown in concentration increasing to 7 g/L, suggesting that a concentration of Na 2 S 2 O 4 that is too low or too high is not conducive to indigo dyeing. If the concentration of Na 2 S 2 O 4 was low, the redox potential of the dye solution was not sufficient to reach that of leucoindigo, resulting in an inefficient reduction and dyeing of the fibers with the dye.…”

Abundant Organic Dye as an Anolyte for Aqueous Flow Battery with Multielectron Transfer

“…IC-Na contains a CC bridged structure with one six-membered and another five-membered aromatic ring on each side. IC-Na is a blue crystalline powder with a purplish luster due to the conjugation of the double bonds. − In the molecular structure of organic crystal IC-Na, electron donor groups (−NH and −OH) and electron acceptor group (CO) are attached by conjugated bonds, which are responsible for the dark blue shade of the IC-Na. In the reduced state, the dark blue color of the IC-Na changes to green, as shown in Figure c.…”

Encapsulating Natural Dyes into Chitosan-TPP Crosslinked Nanoparticles: A Potential Dye Alternative

“…Since natural dyes are mainly derived from plants, larger quantities are required to create the same color intensity as dyeing with synthetic dyes, resulting in higher costs and more waste [5] . The dye used in this study, Indigo, is one of the oldest known blue dyes and requires a long and complicated dyeing process in which the dye has to be reduced in a high alkaline medium (pH [11][12][13][14] with powerful reducing agents like sodium dithionite (Na 2 S 2 O 4 ), which is damaging to the environment due to the production of sulfites, sulfates, and sulfur [9] . Thus, dyeing with natural dyes wastes resources, is expensive, and also requires the use of toxic chemicals, so natural dyes are not a better alternative to synthetic dyes, and should likewise not be used in the clothing industry.…”