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Chrome Dyeing of Wool: Reducing the Amount of Chromium in the Residual Bath
Author(s) -
Benisek L.
Publication year - 1978
Publication title -
journal of the society of dyers and colourists
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.297
H-Index - 49
eISSN - 1478-4408
pISSN - 0037-9859
DOI - 10.1111/j.1478-4408.1978.tb03400.x
Subject(s) - wool , dyeing , chromium , chemistry , residual , potassium dichromate , nuclear chemistry , lactic acid , inorganic chemistry , organic chemistry , materials science , composite material , mathematics , genetics , algorithm , biology , bacteria
The concentration of the residual Cr VI and Or 111 in the dye‐bath can be decreased to acceptable levels by incorporating a‐hydroxymonocarboxylic acids in afterchrome dyeing using the normal dye to dichromate ratios, the most suitable being lactic acid. The mechanism is based on the reduction ofCr VI to Cr 111 which appears to take place predominantly on the wool fibre. The optimum pH range for the treatment is 3.4 to 3.6. Compounds which are substantive to the wool fibre, such as sulphates, or form stable complexes with Cr III such as ethylenediaminetetracetic acid, may increase the amount of the residual chromium in the bath. Other dicarboxylic and hydroxycarboxylic acids, which are also effective in reducing the concentration of the Cr VI in the bath, form stable complexes with Cr 111 , adversely affecting the concentration of the residual Cr 111 in the bath.