Dyeing and Fastness Properties of Wool Dyed with Bromocresol Purple for Halochromic Textile Sensors
Vol. 59, No. 2, pp. 123-130,
Apr. 2022
10.12772/TSE.2022.59.123
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Abstract
Acid or base compounds in industries as well as acid rain are colorless so that
they have difficulty in detecting. In the previous studies, we investigated a nylon chemosensor
for detecting acidic liquids. In this study, we attempted to investigate a wool-based textile
sensor using bromocresol purple as a pH-indicating dye. Dyeing properties of bromocresol
purple on a wool woven fabric were investigated. The pH sensing property was also investigated
by dipping the dyed wool fabric in aqueous solution with different pH values.
Bromocresol purple in an aqueous solution showed maximum absorption at 432 nm with
yellow color at a pH of 2-4, whereas the maximum absorption changed to 589 nm showing
violet color at pH 7. Color yields (K/S) of bromocresol purple on wool were highly dependent
on the dyebath pH. The wool fabric showed a strong orange color when dyed at pH
2. The color of wool dyed at pH 3-6 was yellowish brown or reddish brown, and the color at
pH 7 was grayish blue. The percent exhaustion of bromocresol purple on wool increased as
the pH of dyebath decreased, and a high exhaustion value of 98 to 99% could be obtained
at pH 2-4. When the yellowish brown sample, dyed at pH 4, was immersed in a solution
with a pH range of 4-5, its original color was maintained. Then, the color turned to yelloworange
when immersed in a solution of pH 2-3. When immersed in a solution of pH 6, the
color of the sample changed into brown. The color was also markedly changed into grayish
purple when the sample was dipped in a solution of pH 7-8. The wash fastness of the wool
fabric dyed at pH 3-5 was good to very good. The rubbing fastness were excellent, and dry
cleaning fastness was very good.
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