Bleaching process for broussonetia papyrifera white bast bio-pulp

Abstract

The invention discloses a bleaching method of broussonetia papyrifera white bast bio-pulp, which is passed through a slot screen of 20-60 mesh, and then processed with centrifugal separation, finally processed with supplementary bleaching with alkaline peroxide. The method can remove most colored material in bio-pulp by physical methods of slot screen and centrifugal separation, thereby effectively reducing dirt count in the bio-pulp, the whiteness of the bio-pulp is increased to 80-85 percent ISO from 38-44 percent ISO, the value of KMnO4 is decreased below 5.81 from 14-16, the yield is 90-95 percent, fiber average length is decreased to 6.92 mm from 6.34 mm, requirements of producing white paper or high grade paper classes can be completely fulfilled. Moreover, the method does not use chlorine-containing bleaching agent, has simple technology, low production cost and no environmental pollution. The invention has a wide application prospect in the pulp and paper field.

Description

technical field [0001] The invention relates to a bleaching method of bast fiber in the field of pulp and papermaking, in particular to a bleaching method of mulberry bark biological pulp. Background technique [0002] Existing low hardness pulp, according to different pulping methods, its brightness is all between 20%~40%ISO. In order to meet the needs of producing white paper or high-grade paper, the above-mentioned pulp must be bleached. Traditional bleaching methods use chlorination, alkali treatment, and hypochlorite for three-stage bleaching; modern bleaching methods use chlorine dioxide and other means for multi-stage bleaching. Because all use chlorine-containing bleaching agents in the above-mentioned bleaching methods, such as chlorine gas, hypochlorite, etc., it will inevitably produce a large amount of toxic substances AOX (adsorbable organic halides), which can easily cause serious water pollution. Chlorine dioxide is used for bleaching, although the environme...

AI Technical Summary

Problems solved by technology

Due to the use of chlorine-containing bleaching agents in the above bleaching methods, such as chlorine gas, hypochlorite, etc., it is inevitable to produce a large amount of toxic substances AOX (adsorbable organic halides), which can easily cause serious water pollution.

Chlorine dioxide is used for bleaching, although the environmental pollution load is reduced, but chlorine dioxide bleaching agent is difficult to preserve, and must be used as soon as possible after preparation, and the preparation process of chlorine dioxide is more complicated, and the investment in equipment is relatively large.

The core of the modern new TCF (totally chlorine-free) bleaching method is oxygen-alkali treatment. Although oxygen-alkali treatment does not produce AOX, it requires the use of pressure vessels and oxygen generators. The bleaching process is complicated and the energy consumption is high.

None of the above methods can well meet the requirements of the modern environment-friendly bleaching process. Therefore, it is necessary to develop a new pulp bleaching method that can improve the bleaching efficiency without causing environmental load.