METHOD FOR CARBOXYMETHYLATION OF LIGNOCARBOHYDRATE MATERIALS Russian patent published in 2005 - IPC

FIELD: method for production of carboxymethyl esters useful as adsorbents.

SUBSTANCE: claimed method includes preliminary removing from air-dry lignocarbohydrate material of extractive and water soluble substances by 3-steps subsequent extraction with alcohol/benzene mixture, hot water and cold water. Then macromolecules are cross-linked by polycondensation of extracted material with formaldehyde in ratio lignocarbohydrate material OH-groups/formaldehyde of 1:3-5 in presence of alkali catalyst. Cross-linked lignocarbohydrate material is washed and carboxymethylated with monochloroacetic acid and alkali in ratio lignocarbohydrate material OH-groups/ClCH₂COOH/NaOH of 1:3:27 at 45-65°C for at least 3 h. Obtained product is separated, treated with mineral acid to convert carboxylic groups to H-form; washed with water up to neutral filtrate pH-value, and dried.

EFFECT: product with high content of carboxylic groups, increased change capacity, and stability in aqueous and non-aqueous media.

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