Studies on dyeing with shikonin extracted from Ratanjot by supercritical carbon dioxide

Abstract

Shikonin (di-hydroxy 1,4-napthaquinone), extracted from Ratanjot <i>(Onosma echioides) </i>by supercritical carbon dioxide, has been used to study the kinetics of dyeing on polyester. The main component of this dye has been separated chromatographically, analyzed spectroscopically and then used to study the diffusion coefficient. There is not much difference between the diffusion coefficients of shikonin and main &nbsp;component. On comparing the dyeing results of shikonin with those of other napthaquinone natural dyes Uuglone, lawsone and crude Ratanjot), it is found that the diffusion coefficient of shikonin and main component is intermediate between juglone and lawsone. The diffusion coefficient of the dye extracted by supercritical carbon dioxide is found to be higher than the crude Ratanjot dye.