Acetic Acid → Dichromate acetic acid

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Reaction Steps

Oxidation of reduced sulfur dyes on the fabric is usually effected commercially by a short treatment in a sodium dichromate solution acidified with acetic acid. While such dichromate-acetic acid solutions produce dyed fabrics having good light and wash fastness and wet and dry crock resistance, they nevertheless are unsatisfactory in several respects. Residual chrome salts present in the dyed fibers, even after thorough washing, give the fabric a harsh feel and cause severe friction with over-heating and burning of needles when the dyed fabric is handled on high speed sewing machines and the waste oxidizing solution creates a liquor disposal problem. The liquor disposal problem is particularly troublesome in view of the presence of chromium ions in the waste water. These are toxic and difficult to remove and strict regulations have been proposed by the EPA which limit the amount that can be in the effluent.

Provenance & Evidence