Extraction of natural dye from Dahlia variabilis using ultrasound

Abstract

Performance of ultrasound assisted extraction (UAE) technique for the extraction of colourant from Dahlia variabilis has been compared with conventional solvent extraction method. It is observed that UAE is more efficient process as compared to solvent extraction. The extracted dye is also characterized by FTIR and UV spectrophotometer. Change in colour with pH of extracted dye is observed due to bathochromic shift from blue green (pH 8.9) to deep red (pH 2.0). The extracted dye is also used for dyeing of wool yarns, generally used in the carpet industries. Good fastness properties of dyed yarn confirm its utility in the textile industries for eco-dyeing. The extracted dye also shows good potential to replace phenolphthalein as an indicator.