METHOD OF DELIGNIFICATION AND BLEACHING OF CELLULOSE Russian patent published in 1997 - IPC

FIELD: pulp- and-paper industry. SUBSTANCE: cellulose is preliminarily treated with nitrogen-containing polycarboxylic acid (ethylenediaminetetraacetic or diethylenetriaminepentaacetic acid) at pH 3.1-9.0, advantageously at pH 4-8, followed by washing with water. Cellulose is further treated with hydrogen peroxide or its mixture with oxygen, then with ozone at pH 1-8 using ozone consumption 0.1-20 kg per 1 t of dry cellulose, and finally once again with hydrogen peroxide or hydrogen peroxide/oxygen mixture. EFFECT: enhanced efficiency of process. 4 cl, 5 tbl