Ultrasonic preparation of cationic cotton and its application in ultrasonic natural dyeing

Cationization of cotton fabric was conferred by the sonicator reaction of cellulose with bromoacetyl bromide, followed by substitution of the terminal bromo groups by triethylamine. Experiments showed that the optimal volume of bromoacetyl bromide necessary to succeed the first stage was 0.4 mL. The order of weight gain for various processes indicates, ultrasound, 25 kHz > ultrasound, 40 kHz > mechanical stirring. Also, for the second stage the order of nitrogen contents indicates ultrasound, 25 kHz > ultrasound, 40 kHz > mechanical stirring. The structures of both untreated and cationic fibres were investigated by FTIR spectroscopy. Modified cotton fabric was subsequently dyed in both conventional and ultrasonic techniques with isosalipurposide dye isolated from Acacia cyanophylla yellow flowers. The effect of dye bath pH, ultrasonic power and frequency, dyeing time and temperature were studied and the order of K/S values indicates ultrasound, 25 kHz > ultrasound, 40 kHz > CH. ultrasound was also found to enhance the dye uptake and the overall fastness properties. Analysis of the sorption isotherms of isosalipurposide dye on cationic cotton fabric shows that the Languimir isotherm equation is best able to correlate the data. (C) 2012 Elsevier B.V. All rights reserved.