Hydrogen peroxide oxidation bleaching process pH value stabilizing technology

Abstract

The invention relates to a hydrogen peroxide oxidation bleaching process pH value stabilizing technology, which is mainly used in multiple fields of textiles, papermaking, foods and the like related to hydrogen peroxide bleaching under alkaline conditions. According to the method, magnesium oxide is used as a single alkali source to replace caustic soda, sodium silicate and other alkali sources and buffer agents in conventional hydrogen peroxide bleaching, and the magnesium oxide is slightly dissolved and gradually converted into magnesium hydroxide is utilized to provide a stable pH value forhydrogen peroxide bleaching, so that the effect of the pH value buffer solution is achieved; Mg(OH)2 belongs to a weakly alkaline compound, and the actually measured pH value of the suspension prepared from MgO mineral powder is about 10.24, so that the initial pH value of bleaching is low, the moderate alkali extraction effect is achieved, the COD generation amount in the bleaching process is small, the pollutant generation is reduced, and the material consumption is reduced; and by using magnesium oxide to replace sodium silicate, the problems of bleaching waste liquid viscosity rising andequipment scaling caused by silicon are avoided while the problem of silicon interference in the process for treating the bleaching waste liquid through the heat pump or evaporation concentration method at present is fundamentally avoided.

Description

Technical field [0001] The invention belongs to the industrial application field of hydrogen peroxide oxidative bleaching in textiles, papermaking, food and other industries, and relates to a technology for controlling the pH value of the hydrogen peroxide oxidation reaction process under alkaline conditions. Background technique [0002] The hydrogen peroxide bleaching technology has the advantages of high whiteness, good stability, and less pollution. It is widely used in many industries such as papermaking, textile printing and dyeing, and food. However, the hydrogen peroxide bleaching process is usually carried out under higher temperature or high alkali conditions. For example, cotton fabrics are generally bleached at 90℃ and pH=11.5; the temperature of the pulp fiber bleaching system is between 60-100℃, and the initial pH can reach 13-14, it will cause serious damage to the fiber and affect the fiber yield. At present, the traditional domestic hydrogen peroxide bleaching p...

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Problems solved by technology

In 2006, Chi Congcong and others from the State Key Laboratory of South China University of Technology published "High-yield pulp peroxidation with magnesium alkali instead of sodium alkali" on pages 47-50 of the 25th volume of the 10th issue of "China Paper" in 2006. In the article "Hydrogen Bleaching", it discusses in detail the research on MgO or Mg(OH) from 1991 to 2005 2 The application technology and basic theoretical research results of replacing traditional caustic soda in high-yield pulp bleaching clearly point out that, as confirmed by foreign research and production examples, in hydrogen peroxide bleaching, the use of Mg(OH) 2 Or MgO instead of NaOH, can reduce wastewater pollution, but the above research work is to discuss the stabilizing effect and mechanism of magnesium oxide on the pH value of the bleaching system in the process of hydrogen peroxide bleaching, and there is no relevant research work and production practice at home and abroad in recent years. research work

This is because caustic soda is a strong base with a high initial pH value, high hydrogen peroxide oxidation reaction rate, and high consumption, resulting in low hydrogen peroxide content in the late bleaching reaction system and reduced reaction efficiency. Magnesium oxide has low solubility due to weak alkalinity. In the reaction system, magnesium hydroxide will be gradually formed through the hydration reaction, so that the reaction system is always stable at a lower pH range

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