METHOD OF BLEACHING CELLULOSE Russian patent published in 2020 - IPC D21C9/16 

FIELD: paper; chemistry.

SUBSTANCE: invention relates to methods of bleaching cellulose and can be used in pulp and paper industry in production of cellulose for chemical processing from coniferous and hardwood. Bleaching is carried out by treating cellulose with chlorine dioxide and ozone, then by treatment with an alkali solution in the presence of hydrogen peroxide and magnesium sulphate, then by treatment with hydrogen peroxide and oxygen. Combined treatment with hydrogen peroxide and oxygen adds magnesium sulphate in amount of 0.05–0.7 % of the weight of cellulose. In combined treatment with an alkali solution in the presence of hydrogen peroxide, oxygen is added in amount of 0.15–0.50 % of the weight of cellulose. In combined treatment with hydrogen peroxide and oxygen, oxygen is added in amount of 0.25–0.85 % of weight of cellulose. In combined treatment with hydrogen peroxide and oxygen, hydrogen peroxide is added in amount of 1–5 % of the mass of cellulose.

EFFECT: reduced emissions of organochlorine compounds into production effluents, consumption of chemical reagents for bleaching, increased intrinsic viscosity while maintaining brightness and content of α-cellulose in marketable bleached cellulose.

5 cl, 1 dwg, 1 tbl