Stability of sodium percarbonate_industrial additives

Stability background and overview of sodium percarbonate

Sodium percarbonate is a new oxygen-based bleaching agent composed of sodium carbonate and hydrogen peroxide. Appearance is white, loose and fluid granular or powdery solid. It is easily soluble in water, with a solubility of 12.3 g/100g H2O at 10°C, and as the temperature increases, its solubility also increases accordingly. Sodium percarbonate is a non-toxic substance, but its solid powder or higher concentration solution has certain irritation to the skin, mucous membranes and eyes. However, it does not have any irritating effect in the dilute solution, so it is not suitable for practical use. It will not pollute the environment; it is also a heat-sensitive substance. Dry sodium percarbonate decomposes at 120°C, but when exposed to water, heat, and heavy metals and organic substances are mixed, it can easily decompose into sodium carbonate, water and oxygen. Stability decreases with increasing temperature.

Sodium percarbonate easily dissociates into sodium carbonate and hydrogen peroxide in water. Hydrogen peroxide reacts in an alkaline solution to generate water and oxygen. The generated oxygen has a bleaching effect, thus showing extremely strong bleaching properties. It has the dual properties of sodium carbonate and hydrogen peroxide. The aqueous solution is alkaline, and the pH value of 3% aqueous solution is 10 to 11. Sodium percarbonate neutralizes with acid to form the corresponding sodium salt and releases carbon dioxide, which can be used to quantitatively determine sodium percarbonate. Sodium percarbonate is similar to traditional boron and phosphorus detergent additives. It releases oxygen atoms when exposed to water and exhibits bleaching and sterilizing effects. It is non-toxic and harmless, and can maintain the original color and luster of fabrics. It is very carbonic. Barium is suitable for washing synthetic fibers, disinfecting food tableware, preserving fruits, and can also be used as a sewage treatment agent, oxygen generator, etc.

Stability properties of sodium percarbonate

The theoretical active oxygen value of sodium percarbonate is 15.28%, and its molecular structure includes 3 types: Na₂CO₃·2H₂O₂, Na₂CO₃·nH₂O₂·mH ₂O and 2Na₂C₂O₃·3H₂O₂. Due to different production methods, the properties are also different. The products currently on the market are all Na₂CO₃·nH₂O₂·mH ₂O type, appearance is white, loose, granular or powdery solid with good fluidity, easily soluble in water, with a solubility of 12.3g/100g H2O at 10°C, and as the temperature increases, Its solubility also increases accordingly. Sodium percarbonate is a heat-sensitive substance. Dry sodium percarbonate decomposes at 120°C. However, when exposed to water, heat, or mixed with heavy metals and organic substances, it easily decomposes into sodium carbonate, water and oxygen. Stability decreases with increasing temperature.

So it is necessary to add stabilizers during the production process to obtain sodium percarbonate products with good stability, ensure that they still have high active oxygen content during a certain storage period, and be stored under low temperature and dry conditions. Sodium percarbonate easily dissociates into sodium carbonate and hydrogen peroxide in water. In alkaline solution, hydrogen peroxide generates water and oxygen. The generated oxygen has a bleaching effect, thus showing a strong bleaching effect.

Sodium percarbonate is a non-toxic substance. Its solid powder or higher concentration solution has certain irritation to the skin, mucous membranes and eyes, but it does not have any irritating effect in the dilute solution, so it is It will not pollute the environment during actual use. Sodium percarbonate has the dual properties of sodium carbonate and hydrogen peroxide. The aqueous solution is alkaline, and the pH value of 3% aqueous solution is 10-11. Under neutral or acidic conditions, sodium percarbonate shows certain reducing properties when encountering strong oxidants such as chlorine and potassium permanganate, which can be used as a basis for determining the content of sodium percarbonate. Sodium percarbonate neutralizes with acid to form the corresponding sodium salt and releases carbon dioxide, which can be used to quantitatively determine sodium percarbonate.

Stability application of sodium percarbonate

Stability of sodium percarbonate 1. Detergent additives

The traditional oxygen-based bleach is mainly sodium perborate. Although sodium perborate also has high active oxygen and has been widely used as a component of bleach for a long time, its dissolution rate in water is relatively slow below 20°C. , so the bleaching effect in cold water is not ideal. In addition, there are disadvantages such as higher price and the impact of boron on crops. Sodium percarbonate is odorless and non-toxic, and is easily soluble in cold water. When dissolved in water, it can release oxygen and perform various functions such as bleaching and sterilization, which is in line with the development trend of modern detergents.

In addition, its production cost is lower than sodium perborate, it is suitable for use in cold areas and winter, and it will not cause harm to crops. Therefore, it is gradually replacing sodium perborate in detergents and is increasingly widely used. Adding sodium percarbonate as an active component to detergents can improve its decontamination ability without causing secondary pollution. Compared with traditional chlorine-based bleach, sodium percarbonate is odorless, non-toxic, and non-polluting. The active oxygen it releases has excellent stain removal and whitening functions. Sodium carbonate itself also has good stain removal ability, so it is regarded as An ideal detergent component.

Sodium percarbonate has no strong odor, has no destructive effect on aromatic organic additives and whitening agents, and can maintain its fragrance. It is especially suitable for use as low-phosphorus or phosphorus-free detergents to overcome the impact of phosphorus on water quality. pollution, so it is especially suitable for synthetic fibers, animal fibers, and resin-processed fibers that are not suitable for chlorine bleach.The product is obtained after drying.

6) Other methods of preparing sodium percarbonate

When hydrogen peroxide reacts with sodium carbonate, add an appropriate amount of silicate (sodium metasilicate or sodium silicate) and magnesium salt (magnesium sulfate or magnesium chloride) to react together. The separated massive sodium percarbonate can be processed by the following two methods: ① Add 2.5~8 mass fraction of hydrogen peroxide with a concentration of 1.5%-10% for every 75~92 mass fraction of sodium percarbonate. , the resulting mixture is granulated by tableting method, etc. to obtain sodium percarbonate with low hygroscopicity; ② Add 0.05~15 mass fraction of magnesium salt or diamine tetraacetate for every 100 mass fraction of sodium percarbonate. The resulting mixture can be granulated by tableting or other methods, and sodium percarbonate with good solubility can also be obtained.

Sodium percarbonate is synthesized using ebullating bed technology. The synthesis process is to mix sodium carbonate and hydrogen peroxide solution in an ebullating bed reactor, and blow in air to cause the two to react to form sodium percarbonate microcrystals. Here the crystallites continue to expand until they meet the requirements. The grains are discharged for the coating process, and the coating chamber also uses boiling technology. Compatible inorganic salts are used to form a uniform coating to stabilize the active oxygen of sodium percarbonate. The active oxygen content of sodium percarbonate produced by this method is about 13%.

In the presence of sodium chloride or sodium sulfate, magnesium ions, and hexametaphosphate, sodium percarbonate is prepared through the reaction of sodium carbonate and hydrogen peroxide. Dry sodium percarbonate particles are loaded into the reactor. Then add a hydrogen peroxide solution with a mass fraction of 20% to 70% and a sodium carbonate solution with a mass fraction of 15% to 34% into the reactor at normal temperature to wet the surface of the sodium percarbonate particles to form additional percarbonate. Sodium, the wetted sodium percarbonate is dried in an ebullating bed dryer. The obtained sodium percarbonate particles are solidified with gas through an ebullating bed with a relative humidity of less than 80%, and then the particles of the required size are selected as product.

Need reference materials

[1] Cui Xiaoming. Production and application of sodium percarbonate[J]. Sichuan Chemical Industry, 2004, 7(2): 30-33.

[2] Wang Xiangai, Chen Yangmin. Synthesis and application of sodium percarbonate[J]. Soda Ash Industry, 2006, 2006(4): 7-9.

[3] Zheng Hong ZH. Properties and applications of modern inorganic additive sodium percarbonate[J]. Journal of Yunnan University for Nationalities (Natural Science Edition), 2002, 11(2): 103-106.