Method for extracting pigment from walnut green hulls through subcritical water and using pigment for dyeing

The invention relates to a method for extracting natural pigment from walnut green hulls and using the natural pigment for dyeing and belongs to the field of natural product extraction and application. According to the method, subcritical water serves as an extraction solvent, polyphenol, flavone, anthraquinone, naphthoquinone and other natural pigment in the walnut green hulls are extracted, and a natural pigment extraction solution is directly used for dyeing cotton and wool fabric. The method has the advantages that the active ingredient extraction rate is high, no organic solvent is used in the extracting and dyeing process, the process is environmentally friendly, and products are free of pollution, safe, free of toxicity and the like. No toxic and harmful pigment ingredient is contained in dyed fabric obtained through the method, and the method is suitable for dyeing the various cotton and wool fabric and particularly suitable for dyeing infant articles for use, underwear and other articles due to the fact that the natural pigment of the walnut green hulls further has anti-bacterium activity, anti-oxidation activity and the like.