Process for extracting natural dyes from walnut shells and henna

摘要

As an example of materials containing natural dyes, walnut shells and the powdered leaves of Lawsonia inermis (henna) were extracted with liquid or compressed carbonic acid while varying the temperature, pressure and moisture content, giving yields of active substance of up to 96 %. In comparison with conventional extraction methods, that proposed is more effective and less complex, as a result of which recourse to juglone as a cosmetic dye could be of interest.