Preparation method of trisodium citrate

Trisodium citrate is an organic compound with no peculiar smell and a cool, salty and spicy taste. It is a common raw material in the food industry. There are many ways to make it, such as using citric acid and sodium hydroxide, or using calcium citrate and sodium hydroxide, etc. Trisodium citrate is often used in the food industry or in the production of some medicines.

Preparation method

According to the different raw materials, the preparation methods of sodium citrate are mainly

1. Citric acid + sodium hydroxide method

This is also the earliest production process researched and developed. Dissolve citric acid in water and add it into sodium hydroxide solution. A neutralization reaction occurs and a large amount of heat is generated. The finished product is obtained through filtering, concentrating, crystallizing, and drying. This method has a simple process and good product purity; the disadvantage is that the production cost is high. Now it is only used to prepare laboratory supplies.

2. Citric acid + pure alkali method

The neutralization method improves the process. The pure alkali as raw material is easy to purchase and store and has the advantages of low production cost. It is a production method currently widely used by various industrial enterprises.

3. Citric acid + baking soda method

This method is an improved preparation method for the pure alkali method products which are not suitable for the pharmaceutical industry. This method uses high-quality baking soda, which is dissolved in water according to the calculated amount and then neutralized with citric acid. After concentration and crystallization, pharmaceutical-grade sodium citrate is prepared. Its characteristics are mild reaction conditions, good product quality and good process operability. At present, this method is mainly used in some pharmaceutical factories.

4. Calcium citrate + pure alkali method

This method utilizes the double decomposition reaction of calcium citrate and pure alkali, and the insoluble matter is filtered out to obtain sodium citrate. The product purity is poor and the operation process is long. A few years ago, it was reported that by adjusting the pH value of the mixing conditions, the process was simplified, the production cost was reduced, and better quality products were obtained.

Recently, some people have adopted the resin exchange method to produce sodium citrate. The fermentation clear liquid is exchanged with ion resin, and the adsorbed citric acid is eluted with sodium hydroxide solution. The obtained sodium salt solution is concentrated and crystallized to obtain the sodium citrate product. This method is pollution-free and low-cost, and is a path that citric acid fermentation manufacturers should develop.