Comparison of sodium dithionite and glucose as a reducing agent for natural indigo dyeing on cotton fabrics

Abstract

Abstract.A traditional reducing agent in an indigo dyeing process with cotton fabrics is sodium dithionite (Na2S2O4) which is environmentally unfavorable because the resulting by-products cause various problems to the disposal wastewaters. In this research, glucose was used as a possible replacement of Na2S2O4 in indigo dyeing. The comparison of reduction power of Na2S2O4 and glucose for natural indigo dyeing on cotton fabrics based on reduction potential was analyzed. The optimum reduction temperature for natural indigo dye of both reducing agents was at 70 o C. The reduction time did not have a significant effect on the reduction potential under the condition studied. Na2S2O4 could give higher color strength than glucose. However, wash fastness of the fabric samples from a glucose reduction was slightly better than Na2S2O4 ones. Hence, glucose virtually has a potential to be used as a green reducing agent in natural indigo dyeing.

Impact of an in-situ Cr(VI)-contaminated site remediation on the groundwater

“…The described Cr(VI) mobilization (desorption) and subsequent reduction after day 178 leads to an increase in the Cr (tot) concentration in the groundwater. However, the removal of Cr (tot) through precipitation of the Cr-Fe hydroxide was prohibited due to instant reduction of (dissolved and newly formed structural) Fe(III) to Fe(II) by the injected reducing agent (Sass and Rai 1987;Palmer and Puls 1994;Su and Ludwig 2005;Saikhao et al 2017). Except for the end of the injection period (after day 211), when the pH was relatively low (pH < 6), the pH-controlled dissolution of Cr(III) hydroxide, or Cr(III)-Ca-containing hydrocalcite, which were inferred to be present at this site by Sedlazeck et al (2017), can be excluded as an additional source for increasing Cr (tot) (i.e., Cr(III)) concentrations.…”

“…The Na 2 S 2 O 4 dissolution process produces the dithionite ion (S 2 O 4 2− ), but this newly formed ion is rather unstable. Consequently, it will further react, generating to a variety of reaction products, as summarized by Amonette et al (1994): dissociation and disproportionation produces sulfoxyl radicals (SO 2 (Mayhew 1978;Amonette et al 1994;Su and Ludwig 2005;Saikhao et al 2017). Even though redox reactions between S 2 O 3 2− , or its disproportionation products, and Cr are known (Avakian et al 2005;Demoisson et al 2007 , and HSO 3 − are known to be the relevant ones for reducing Cr(VI) to Cr(III) (Palmer and Wittbrodt 1991;Amonette et al 1994;Cheng et al 2009;Kaprara et al 2018).…”

Dyeing Chemicals

“…Surfactants are classified into different ways such as use, ionic charge, and chemical structure. According to the ionic structure, surfactants can be classified into four categories: anionic, cationic, amphoteric, and nonionic [39]. Anionic surfactants are surfactants that are ionized into anions and cations but the anion is the dominating ion in the solution.…”

“…Beginning of the nineteenth century, sodium dithionate (Na 2 S 2 O 4 ) was introduced as a reducing agent for the vat dyeing process [8]. Effective sodium dithionate, also called hydrose, provides an effective reduction in indigo dyes [44]. Stripping methods, mostly used in textile finishing, can remove dye from colored fabric.…”

Insights into the dyeing using natural indigo (Indigofera tinctoria): Toward an environmentally friendly garment

“…11 Glucose, for example, is oxidised to gluconate species while simultaneously reduces insoluble indigo to leuco indigo form. 11 Saikhao et al 12 have compared the reducing power of glucose with that of sodium hydrosulphite and found close dyeing properties. Likewise, fructose leads to a rapid reduction of indigo.…”