Inhibition of ultrasonic decolorization of rhodamine B in presence of organic substances

Abstract

Ultrasonic waves obtained from Mullard's high-frequency ultrasonic generator type E-7562 with a barium titanate transducer having a frequency of 1 Mc./sec. were passed into the aqueous solution of rhodamine B and it was found that the solution was decolorized after some time. These waves were found to decolorize aqueous solutions of congo red, chrysoidine, aniline blue and brilliant green also. 20 ml. of an aqueous solution (0.0064 gm./l.) of rhodamine B and 5 ml. distilled water in a Jena glass bottle were held vertically above the transducer and the position so adjusted as to produce maximum fountain inside the vessel on passing the ultrasound. When, however, 20 ml. of the same solution and 4 ml. of distilled water were taken and 1 ml. of methyl alcohol, ethyl alcohol, n-propyl alcohol, n-butyl alcohol, diacetone alcohol, acetone, dioxan or ether were added separately, and the mixtures exposed to ultrasonic radiation under the same conditions as before, very little change in colour was observed, even when the time of exposure of the solutions containing these substances was almost doubled (Table 1). The colorimetric readings were recorded on a Klett Summerson photoelectric colorimeter using a No. 54 filter, which covers a range of 520-580 mµ. Readings for the dye solution exposed without adding any organic substance are shown in the second column (blank).