Concerned about the creation of a new era of environmental protection, in the next century, hydrogen peroxide will occupy a prominent position in the bleaching chemical Lu. It is a beneficial bleach that does not form a poison and is conducive to environmental protection.
Originally, hydrogen peroxide was mainly used for mechanical bleaching. Nowadays, there is a rapid increase in the bleaching of chemical and deinked pulps.
Alkaline hydrogen peroxide can achieve high brightness and high stability in the bleaching of mechanical pulp, and can not increase the strength under high yield conditions. The single-stage bleaching from Zhongyuan has now developed to high-concentration single-stage and two-stage bleaching. There is a complete control system in the bleaching process, with on-line optical test heads and test heads for residual chemicals. Today's softwood CTMP pulp has a bleaching brightness of 80 degrees centigrade ISO and a hardwood pulp score of 85 degrees centigrade ISO.
Bleaching of chemical pulp is a controversial issue. Due to the presence of traces of dioxins in the bleach liquor, bleaching has been promoted towards bleaching than elemental chlorine has begun a decade ago in order to eliminate organic chloride production.
In the advancement of process technology, hydrogen peroxide has become a major bleaching agent in the absence of elemental chlorine bleaching (ECF, chlorine dioxide-based bleaching process) and bleaching without chlorine (TCF). Hydrogen peroxide is used as a true bleach to achieve high brightness, and the development is faster taking into account environmental protection factors. Three years ago, pressurized oxygen bleaching at 100 degrees Celsius was perfected in many factories. The hydrogen peroxide bleaching efficiency is further enhanced, and the cost of the bleaching can also be saved.
In the future, hydrogen peroxide, oxygen, chlorine dioxide, and ozone will be the main bleaching agents. The final research and development goal is to achieve a pollution-free discharge (TEF) from a chemical pulp mill.
Due to the impact of environmental protection, recycling of waste paper will be an important development trend. Hydrogen peroxide is used in all three stages of deinking of waste paper.
In the past, traditional practice was to add hydrogen peroxide together with other deinking chemicals into the pulper to reduce the "blackening" of the fibers under alkaline conditions. At the same time, it can oxidize the no-ink adhesive material to accelerate the removal of the ink particles. In this application, it played a good role in the deinking of old newspapers, old magazines and other waste paper containing wood pulp. In other deinking processes, it can be used in subsequent concentrated bleaching towers or in high-concentration bleaching towers to increase whiteness by 3-10%. It often achieves higher whiteness than using bleach alone. A process can be proposed to combine hydrogen peroxide with bisulfite for bleaching, giving it the flexibility to produce different grades and different products. In order to obtain a deinking commercial pulp, a modern deinking plant uses pressurized hydrogen peroxide bleaching to provide the potential for color removal of office mixed waste paper, mechanical pulp, and unbleached fibers that are contaminated with chromic substances.
In a deinking line, a thermal dispersion system is often included to reduce the particle size of the visible ink particles in the pulp. However, such treatment will also have an adverse effect on whiteness. Due to the optimisation of the bleaching conditions, the additional advantage of adding hydrogen peroxide to the dispersion is to increase the efficiency of subsequent flotation. In a modern deinking plant, the dispersion system is combined with the subsequent bleaching of hydrogen peroxide.
Originally, hydrogen peroxide was mainly used for mechanical bleaching. Nowadays, there is a rapid increase in the bleaching of chemical and deinked pulps.
Alkaline hydrogen peroxide can achieve high brightness and high stability in the bleaching of mechanical pulp, and can not increase the strength under high yield conditions. The single-stage bleaching from Zhongyuan has now developed to high-concentration single-stage and two-stage bleaching. There is a complete control system in the bleaching process, with on-line optical test heads and test heads for residual chemicals. Today's softwood CTMP pulp has a bleaching brightness of 80 degrees centigrade ISO and a hardwood pulp score of 85 degrees centigrade ISO.
Bleaching of chemical pulp is a controversial issue. Due to the presence of traces of dioxins in the bleach liquor, bleaching has been promoted towards bleaching than elemental chlorine has begun a decade ago in order to eliminate organic chloride production.
In the advancement of process technology, hydrogen peroxide has become a major bleaching agent in the absence of elemental chlorine bleaching (ECF, chlorine dioxide-based bleaching process) and bleaching without chlorine (TCF). Hydrogen peroxide is used as a true bleach to achieve high brightness, and the development is faster taking into account environmental protection factors. Three years ago, pressurized oxygen bleaching at 100 degrees Celsius was perfected in many factories. The hydrogen peroxide bleaching efficiency is further enhanced, and the cost of the bleaching can also be saved.
In the future, hydrogen peroxide, oxygen, chlorine dioxide, and ozone will be the main bleaching agents. The final research and development goal is to achieve a pollution-free discharge (TEF) from a chemical pulp mill.
Due to the impact of environmental protection, recycling of waste paper will be an important development trend. Hydrogen peroxide is used in all three stages of deinking of waste paper.
In the past, traditional practice was to add hydrogen peroxide together with other deinking chemicals into the pulper to reduce the "blackening" of the fibers under alkaline conditions. At the same time, it can oxidize the no-ink adhesive material to accelerate the removal of the ink particles. In this application, it played a good role in the deinking of old newspapers, old magazines and other waste paper containing wood pulp. In other deinking processes, it can be used in subsequent concentrated bleaching towers or in high-concentration bleaching towers to increase whiteness by 3-10%. It often achieves higher whiteness than using bleach alone. A process can be proposed to combine hydrogen peroxide with bisulfite for bleaching, giving it the flexibility to produce different grades and different products. In order to obtain a deinking commercial pulp, a modern deinking plant uses pressurized hydrogen peroxide bleaching to provide the potential for color removal of office mixed waste paper, mechanical pulp, and unbleached fibers that are contaminated with chromic substances.
In a deinking line, a thermal dispersion system is often included to reduce the particle size of the visible ink particles in the pulp. However, such treatment will also have an adverse effect on whiteness. Due to the optimisation of the bleaching conditions, the additional advantage of adding hydrogen peroxide to the dispersion is to increase the efficiency of subsequent flotation. In a modern deinking plant, the dispersion system is combined with the subsequent bleaching of hydrogen peroxide.