Monday, November 3, 2008

Methylene Blue Absorption

Bleaching is the most important process in textile wet processing which gives white goods. Methylene blue absorption is one of the several methods to estimate the bleaching efficiency.

The absorption of methylene blue by cellulose derivative is generally due to the -COOH groups present in oxycellulose formed by alkaline oxidation (due to bleaching agent) but it may also be due to mineral acids which have been dried into cellulose and are not easily washed out.
The method depends upon treating the sample with a methylene blue solution of known strength and buffered to a known pH and determining the concentration of the methylene blue in the solution either by titration with naphthol yellow or by colorimetric method.

Procedure by titration method

A sample of 2.5 gm weight is placed in test tube or small flask. 15cc of methylene blue is added from burette. The titration is carried out at room temperature. 10cc of solution is withdrawn and titrated with naphthol yellow S. The ethylene blue absorbed by sample is calculated in milimoles per 100gm of dry sample.

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