LOCAL PLANT DYES AND THEIR APPLICATION IN TITRATION, DYEING OF FABRICS AND PAPER by U. D. AKPABIO and N. E . U. INYANG

ABSTRACT
Local gin (50% ethanol/water)) extracted 8.5% of orange-reddish dye from the seed of Sterculia tragacantha while methanol extracted I2..1% wine red dye from the rhizome of Zingiber officinale. The IR and the UV absorption characteristics and the results of the chemical analysis indicated that these dyes are of hydroxyanthraquinone class. The dye extract from Sterculia tragacantha gave persistent orange colour to white synthetic fabric (Satin) but stained while paper pink while extract from Zingiber officinale dyed natural while cotton fabric. paper and satin fabric bright yellow. The colours were fast to water, washing detergent solutions and to dayiight. The dye from Zillgjber officinale was also found suitable as colour indicator in pH titration of a strong acid against a strong, base, therefore serving as a substitute for the methyl orange standard indicator in volumetric analysis.
Recommendation for adoption in practical Chemistry exercises in Secondary Schools is made.