Sodium hexametaphosphate: The all-rounder of the chemical world

Introduction

In the vast field of chemistry, there is a compound called sodium hexametaphosphate, which has become a bright pearl in the chemical field with its unique chemical properties and wide application fields. This paper will explore its properties, preparation, application, and impact on human life.

Overview

Sodium hexacaphosphate, also known as Granham salt, has the chemical formula (NaPO₃)₆ and a molecular weight of 611.77. It is a colorless transparent glass or white granular substance with a melting point of up to 616°C (decomposition), easily soluble in water, but insoluble in organic solvents. Sodium hexametaphosphate has a strong hygroscopic property, which can gradually absorb water in the air and be viscose. This unique property makes it have a wide range of applications in many fields.¹

Preparation

There are a variety of preparation methods for sodium hexametaphosphate, the following are some of the main preparation methods:

Sodium dihydrogen phosphate method

This method is by neutralizing the soda ash solution and phosphoric acid at 80 ~ 100℃, the generated sodium dihydrogen phosphate solution is evaporated, concentrated, cooled, and crystallized, and sodium dihydrogen phosphate dihydrate is prepared. The crystal water is then removed by heating and dehydrated at further heating to 620℃，and the resulting sodium metaphosphate melt is polymerized into sodium metaphosphate.

Phosphorus pentoxide method

The method is to mix the phosphorus pentoxide obtained from the combustion and oxidation of yellow phosphorus in the dry airflow with soda ash in a certain proportion, and then heat it indirectly in the graphite crucible to dehydrate and melt together, and the generated sodium hexametaphosphate melt is made by sudden cooling and grinding to produce the finished product.

Phosphoric anhydride method

The yellow phosphorus is heated and melted into the oxidation combustion furnace, and the oxygen in the dry air is used for the oxidation combustion reaction to generate the intermediate product phosphoric anhydride. Then the phosphoric anhydride was mixed with soda ash, and after a high-temperature polymerization reaction, the flake sodium hexametaphosphate was prepared by sudden cooling. Powdered sodium hexametaphosphate can be obtained by grinding.²

The differences between these preparation methods mainly lie in the selection of raw materials and different reaction conditions, but they can effectively prepare sodium hexametaphosphate.

Application

Due to its unique properties, sodium hexametaphosphate has a wide range of applications in many fields:

Food industry

Used as a quality improver in the food industry, it has the effect of chelating metal ions, which can prevent protein precipitation and denaturation, thereby improving the stability and quality of food. It can be added to foods to improve taste and stability, such as meat products, dairy products, flour products, etc.

Daily chemicals

Daily chemicals, can be used as a water softener, which can form stable complexes with cations such as calcium and magnesium in water, reduce the hardness of water, and play a role in softening water quality. Therefore, it is often used to prepare household washing liquid, body wash, and other products to reduce the impact of hard water on skin and clothing.

Paint industry

In the paint industry, it can be used as a dispersant, which can effectively inhibit the repulsive force between pigment particles and promote its uniform dispersion in the paint base, thereby improving the quality of the paint film.

Water treatment field

Can be used as boiler water and industrial water softening agent, its anions can form soluble complexes with calcium and magnesium plasma in water, so that these ions are difficult to crystallize out, to achieve the purpose of softening water.

Detergent industry: In detergent, it is a good crystal shape control agent, which can be adsorbed on the surface of dirt particles to prevent their accumulation and deposition. Therefore, it is often added to washing powder or other detergents to improve the washing effect.³

 Security

Regarding the safety of sodium hexametaphosphate, it needs to be clear that it is divided into food grade and industrial grade. Food-grade sodium hexametaphosphate has developed a reasonable amount of added standards, so it is safe to add food-grade products to food. However, because industrial-grade sodium hexametaphosphate does not remove other harmful chemicals from the body, it may cause damage to the body after misuse, especially the respiratory system and cardiovascular systems. Therefore, when using it, it is necessary to clarify its purpose and level and follow the relevant safety operating procedures.⁴

Future development

With the progress of science and technology and the increasing requirements of people for environmental protection and health, the application field of sodium hexametaphosphate is also expanding and deepening. In the future, it is expected to show broader application prospects in new energy, environmental protection materials, biomedicine, and other fields. At the same time, with the continuous improvement and optimization of the preparation technology, the production cost will continue to reduce, making it widely used in more fields.⁵

Conclusion

As an important chemical substance, sodium hexametaphosphate has shown its unique value and charm in many fields. Through the introduction of this paper, we can not only understand the properties of sodium hexametaphosphate, preparation methods, and application fields but also realize its safety and future development prospects.

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