Comparative kinetics studies of ribose and galactose as eco-friendly reductants for leuco dye formation

Reduction of the dye is a significant process in the textile industry as it renovates the dye into water-soluble leuco dye for fixing it into a fibre. The current investigation explores the reduction kinetics of thionine dye (Th) in relation to the sugars consistent with the carbon chain to get a leuco dye state by an ecologically friendly reductant. For this purpose, galactose and ribose, the carbohydrate family with five and six carbon atoms, were selected, respectively. Reduction kinetics of Th with ribose and D-galactose monitored spectrophotometrically at λ_max 599 nm to optimize the different parameters as an essential step in leuco dye formation for dye fabrication. The results initially showed slow reduction kinetics, which later proceeded fast under different studied parameters, including the concentration of the dye, reductant, alkali and at different temperatures. The reaction followed pseudo-first-order kinetics in the presence of atmospheric oxygen. The results showed that the rate of the kinetics of Thionine with ribose was more influential than galactose keeping all parameters constant. A mechanism consistent with the above findings has been discussed in the relevant section of the paper.