Method of bleaching pulp

 

(57) Abstract:

The inventive when bleaching pulp with hydrogen peroxide in alkaline medium as organic additives used ortho-phenantroline in an amount of 0.01 to 1.0% by weight of the absolutely dry fiber. Then the pulp is subjected to alkaline treatment and kislovka. table 1.

The invention relates to a process of bleaching cellulose and can be used in the production of fibrous materials for various purposes.

Known methods of bleaching pulp by multi-processing unbleached fibrous mass of chlorine, alkali, sodium hypochlorite, chlorine dioxide, alkali, again by chlorine dioxide and kislovka [1] the Disadvantage of these methods is the multistage process of bleaching and the use of toxic chlorine-containing reagents.

Closest to the proposed to the technical essence and the achieved effect is a method of bleaching lignocellulosic material, which consists in the treatment of pulp with oxygen and peroxides in the presence of cyclic catasetinae and/or amines in alkaline medium [2]

However, the use of gaseous oxygen in the bleaching requires special equipment delakorda most effectively at temperatures above 100aboutC.

The purpose of the invention to simplify the process of bleaching, increased white fibrous material.

This task is solved by the bleaching of cellulosic materials by hydrogen peroxide in alkaline medium at 60-90aboutIn the presence of organic additives catalytic type, which use ortho-phenantroline as 0.01 to 1% by weight of the absolutely dry. C.) fiber.

The use of the additive ortho-phenanthroline allows to exclude the use of gaseous oxygen and at the same time to achieve the same white indices at lower times peroxide bleaching, carry out the process at lower temperatures and at lower temperatures and with lower consumption of hydrogen peroxide than without the additive, indicating that the increase of the efficiency of bleaching.

According to the proposed method subjected to bleaching of unbleached sulphate pulp hardwood rigidity 16% Kappa (white 35%). Cook the pulp suspension to a concentration of 10% in the solution containing 2-6% hydrogen peroxide (by weight and. C. fiber), sodium hydroxide in the amount of 2-3% by weight of the fiber (pH 10.5-11.5) and a portion of the proposed additions ortho-penetralia (0,01-1% ). Together controI 60-90aboutFor 15-240 minutes Then spend the bucking weight within 5-10 min, a solution of NaOH (pH 12) and kislovka solution SO2(pH 3-5) for 5-10 min, after which the fiber is washed with water and prepare a standard casting to determine white leucometer according to GOST 7690-66.

P R I m e R 1. 1, and. C. unbleached pulp is poured 10 ml of alkaline hydrogen peroxide solution containing 2% of hydrogen peroxide, 3% sodium hydroxide and 0.5% ortho-phenanthroline. The mass is well stirred, placed in a thermostat heated to 85aboutC, and incubated for 60 minutes after the mass bleaching leach, then kislovka and washed with water, and then prepare a standard casting to define whiteness. The whiteness index of the sample bleached thus cellulose 64.0% Parallel conduct Supervisory experience without the addition of ortho-phenanthroline. White control sample 61.5%

P R I m m e R 2. The order of conducting the process of pulp bleaching is the same as in example 1. The differences are: the consumption of hydrogen peroxide 4% by weight. C. cellulose, ortho-phenanthroline 0,01% process temperature bleaching 75aboutWith time bleaching 120 minutes White sample is 67.5% of the control sample has a white 66.5%

P R I m e R the temperature conditions, the duration of the bleaching, the concentrations of reagents, flow additives (as proposed and known in the prototype), presented in the table.

The bleaching results show that the addition of ortho-phenanthroline has a strong catalytic effect on the process of peroxide bleaching. Analysis of the results carried out in the table shows that the same indicators of white fibrous material can be achieved in the control experiments, i.e., without the proposed additions, varying the time and temperature of the bleaching process, the concentration of whitening reagent (examples 5 and 11, 8 and 14, 9 and 15).

The use of the additive ortho-phenanthroline allows to reduce the time of bleaching, to reduce the process temperature or the flow rate of hydrogen peroxide (examples 5 and 7, 5 and 12, 13 and 15), to improve the performance of the white pulp with the same control parameters of the process.

The table below shows results on the influence of flow additives on white fibrous material (examples 2, 17-24, 27) show that the optimal consumption is ortho-phenanthroline 0.05 to 0.1% by weight. C. fiber. A further increase of the flow rate of the additive to 1.0% reduces the whiteness of the sample, giving it a slightly reddish tint (from 72.5 to 69.0% at 60

Thus, the application of the proposed method of bleaching can simplify the apparatus bleaching process, to improve the efficiency of the process and the white fibrous material.

METHOD of BLEACHING CELLULOSE by treatment with hydrogen peroxide in alkaline medium in the presence of organic additives with subsequent alkali treatment and kislovka, characterized in that the organic additives used ortho-phenantroline in an amount of 0.01 to 1.0% by weight of the absolutely dry fiber.

 

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