Scaling in sodium silicate and hydrogen peroxide bleaching
In hydrogen peroxide bleaching, adding an appropriate amount of sodium silicate can buffer the pH value during bleaching, and can reduce the adverse effects of transition metal ions, reduce the ineffective decomposition of hydrogen peroxide, thereby improve the bleaching efficiency and increase the whiteness of the slurry. Therefore, sodium silicate has been widely used by manufacturers that use hydrogen peroxide for bleaching.
But on the other hand, sodium silicate also brings some troubles to the production process of hydrogen peroxide bleaching,which is mainly manifested in the formation of scale layer in the equipment and pipeline, shortening the cycle of shutdown cleaning and replacement of equipment parts, and reducing the production efficiency.
What are the causes and characteristics of scaling?
The scaling phenomenon varies with raw materials, production process and products. The scaling problem of softwood pulp production is more serious. The scaling mainly occurs in sodium silicate storage tank and its pipeline, bleach preparation device and its pipeline, disc mill, slurry mixing device and bleached pulp dehydration device.
The investigation on the cause of scale formation shows that under certain conditions, sodium silicate will polymerize into macromolecules, precipitate from the solution, adhere to the metal surface and form a scale layer. Silicate is stable in alkaline condition, but it will lose its stability in acidic condition. When the ratio of silica to calcium or silica to magnesium is large, calcium ions or magnesium ions will combine with silicate polymer to form precipitation. In hydrogen peroxide bleaching, when calcium ion and magnesium ion exist at the same time, sodium silicate preferentially reacts with magnesium ion to form magnesium silicate precipitate, which is soft, talc like and does not adhere to the surface of stainless steel. However, calcium silicate precipitation will form a scale layer on the metal surface.
The above is a brief introduction of the scaling of sodium silicate and hydrogen peroxide bleaching by Chengzhi industry, and hopes to help you. Zhengzhou Chengzhi Industrial Co., Ltd. is a modern technology enterprise engaged in the research, development, production and sale of fine chemical and biological enzyme products. The main products of the company are: hydrogen peroxide stabilizer, oxygen bleaching intensifier, bleaching activator, hydrogen peroxide promoter, chelating agent, cooking aid, sewage decolorizer, sodium silicate substitute, etc. Welcome to consult and understand.
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