Catalyzed alkaline hydrogen peroxide bleaching of dye-containing cellulose textiles
First Claim
1. A process for decolorizing a cellulose textile bearing oxidized vat dye comprising the steps ofa) contacting the cellulose textile with an aqueous solution of hydrogen peroxide containing an amount of a hydrogen peroxide catalyst comprising a water-soluble lower alkyl quaternary amine salt, sufficient to oxidize vat dye in the fabric until said dye is decolorized by oxidation;
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Abstract
A process for decolorizing a cellulose textile bearing oxidized vat dye comprising contacting the cellulose textile with an aqueous solution of hydrogen peroxide containing an amount of a hydrogen peroxide catalyst sufficient to oxidize vat dye in the fabric until the dye is decolorized by oxidation. Then the cellulose textile is separated from the aqueous solution. The hydrogen peroxide catalyst can be a water-soluble lower alkyl quaternary amine salt such as a dihydroxypropyltrimethylammonium halide, chlorohydroxypropyltrimethylammonium halide or epoxypropyltrimethylammonium halide, or it can be a transition metal ion such as a cupric or stannous metal ion present in an amount of from 0.1 to 2 ppm. The process is suitable for decolorizing denim bearing vat dyes such as indigo, and is particularly suitable for decolorizing denim scrap.
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Citations
11 Claims
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1. A process for decolorizing a cellulose textile bearing oxidized vat dye comprising the steps of
a) contacting the cellulose textile with an aqueous solution of hydrogen peroxide containing an amount of a hydrogen peroxide catalyst comprising a water-soluble lower alkyl quaternary amine salt, sufficient to oxidize vat dye in the fabric until said dye is decolorized by oxidation; - and
b) separating the cellulose textile from the aqueous solution. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A process for decolorizing a cellulose textile bearing oxidized vat dye comprising the steps of:
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a) contacting the cellulose textile with an aqueous solution of hydrogen peroxide containing an amount of a hydrogen peroxide catalyst comprising a cupric or stannous metal ion present in an amount of from 0.1 to 2 ppm sufficient to oxidize vat dye in the fabric until said dye is decolorized by oxidation; and b) separating the cellulose textile from the aqueous solution.
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Specification