How Disodium Diphosphate is Made?

In previous articles, we have introduced Disodium Diphosphate(E450 i, also known as Sodium Acid Pyrophosphate). Today we will dive deeper to discover the source of it, and how it was made.

E450(i) DIPHOSPHATE DISODIUM

Production Process

Raw Material Preparation

Phosphoric acid (H3PO4): Phosphoric acid is one of the main raw materials for the preparation of disodium pyrophosphate. It can be extracted from ores of phosphate rock or other phosphorus-containing minerals, or synthesized by other chemical processes.

Sodium Hydroxide (NaOH): Sodium hydroxide is another important raw material for producing disodium pyrophosphate. It can be reacted with phosphoric acid to form sodium dihydrogen phosphate (NaH2PO4), which is then reacted by further heat treatment to produce disodium pyrophosphate.

Reactor Preparation

Select a suitable-sized reactor made of corrosion-resistant and heat-stable material to accommodate the reactants and reaction mixture. Ensure that the reactor is clean and sterilized to prevent any microbial contamination.

Addition of Phosphoric Acid

Slowly add phosphoric acid to the reactor while controlling the rate of addition. It is crucial to control the addition rate to avoid violent reactions or overflow. Stirring or mixing systems can be employed to ensure the even dispersion of phosphoric acid in the reaction solution.

Addition of Sodium Hydroxide

Gradually add a sodium hydroxide solution to the reactor. The addition rate and dosage should be adjusted based on the reaction conditions and desired chemical reaction. The reaction will commence during the addition of sodium hydroxide, resulting in the formation of disodium diphosphate.

Reaction Control 

Control the reaction temperature and reaction time to ensure the completeness and efficiency of the reaction. The reaction temperature is typically maintained within a specific range to facilitate the reaction. The reaction time depends on the conversion rate of the reactants and the desired product quality.

Reaction Temperature: The reaction temperature is typically maintained within a range of 50°C to 80°C (122°F to 176°F). This temperature range is suitable for promoting the reaction kinetics while ensuring the stability of the reaction mixture. However, it’s important to note that the exact temperature range may vary based on the specific process and reactants used.

Reaction Time: The reaction time can range from several hours to a few days. The duration of the reaction depends on the conversion rate of the reactants and the desired level of product purity. It is determined by monitoring the progress of the reaction and performing periodic quality checks to ensure the desired product specifications are met.

pH Adjustment

Monitor and adjust the pH of the reaction solution during the process to ensure it remains within the appropriate range. pH adjustment may involve the addition of acids or bases to promote the progress of the reaction and the formation of the desired product. In general, the pH range is typically maintained between 6.5 and 8.5. This range provides suitable conditions for the reaction to proceed efficiently and promotes the formation of the desired product.

Stirring or Circulation

Employ stirring or circulation systems to ensure proper mixing of the reaction mixture, promoting reaction rates and effectiveness. Stirring or circulation systems also help maintain uniformity and temperature distribution in the reaction solution.

Reaction Termination and Product Handling

Determine the end of the reaction based on the predetermined reaction time. Cease heating and stirring, and remove the reaction solution from the reactor. Subsequently, process the reaction mixture through filtration and purification steps to remove solid impurities and unreacted substances.

Crystallization and Drying

Subject the filtered solution to a crystallization process to obtain crystals of disodium diphosphate. The crystallization process can be facilitated by controlling temperature and stirring speed to promote crystal formation and growth. After crystallization, separate the crystal product and subject it to appropriate drying to remove residual moisture, resulting in dry disodium diphosphate.

Quality Control

Perform quality control tests on the obtained disodium diphosphate, including chemical analysis and physical property tests, to ensure compliance with food regulations regarding safety and quality standards. These tests may involve measuring pH, moisture content, impurity levels, and other relevant parameters.

That is the whole process of how disodium diphosphate was made. In summary, disodium diphosphate (E450i), also known as sodium acid pyrophosphate, is produced by reacting phosphoric acid with sodium hydroxide. The reaction is carefully controlled in terms of temperature, time, and pH. The resulting disodium diphosphate is obtained through a series of steps, including raw material preparation, reactor setup, the addition of phosphoric acid and sodium hydroxide, pH adjustment, stirring or circulation, reaction termination, filtration and purification, crystallization, drying, and quality control testing. The production process ensures the desired product quality and compliance with food safety regulations. Disodium diphosphate finds extensive use as a multifunctional food additive in various applications, such as emulsification, stabilization, acidity regulation, leavening, antioxidation, emulsifying salt stabilization, and moisture retention.