Sodium diacetatic (SDA) is a product from the hydrogen binding reaction of sodium acetate and acetic acid. It is a high-performance preservative agent
and it has several characteristics: 1) Trophicity. It is an additive in animal feed to increase the trophicity of animal feed effectively. And the animal feed which contains the SDA can improve the growth of pigs and milk performance. 2) Special taste. The sour taste of SDA can cover all the bad odor of other synthesis additives in the feed. 3) High-performance. The efficiency of SDA is much higher than traditional preservative agents. For example, the dosage of SDA is only half or one third of sodium propionate and the price of SDA is much lower. 4) Security. SDA has no toxic effect to human and animals.
Right now, the production technologies of SDA are acetic acid-sodium acetate solution-phase combinatorial synthesis method, acetic acid-sodium acetate vapor synthesis method, aceticanhydride-sodium acetate solution-phase combinatorial synthesis method, acetic acid-aceticanhydride-sodium acetate solution-phase combinatorial synthesis method, and acetic acid-sodium carbonate synthesis method.
Acetic acid-sodium carbonate synthesis method was widely used now. Production cycle of this method was short and product yield was high. So this study was to optimize the conditions in the synthesis process.
- Principle of synthesis process
After the charging the reactants into the reactor, the product was synthesized and drying according to the equilibrium. The pure product can be obtained after cooling.
- Synthesis process
Pure acetic acid was added into the reactor. First, water/acetic acid (92:8, v/v) was mixed with pure acetic acid. Then sodium carbonate was added and stirring at the same time. After charging, because of the exothermic reaction, the temperature inside of the reactor will be increased to 80 ~ 90 ℃. The temperature should be fixed until the reaction was finished. After the reaction was finished, the powder of product should be dried under 30 ~ 40 ℃.
RESULT AND DISCUSSION
- Effect of solvent/solid ratio
shows that different amounts of SDA can be obtained by different solvent/solid ratio. The results reveal that acetic acid: sodium carbonate (mol : mol) = 8.916 : 1 is the optimum ratio.
Effect of solvent/solid ratio of product yield
aacetic acid. bsodium acetate
- Effect of order of the reactants
In the reaction, the order of the reactants can affecpt the purification of the product. The water/acetic acid (92 : 8, v/v) should be added into the reactor before sodium carbonate. Because after the sodium carbonate added into the solvent, SDA can be synthesized and dissolved in water at the same time. After the reaction finished, SDA will be recrystallized from the water.
- Reaction time and temperature
When the temperature in the reactor was higher than 90 ℃, the reactants will be destroyed. In the other hand, if the temperature was lower than 80 ℃, there was no enough energy to continue the reaction. Also the reaction time was fixed as 30 min. If the time was too long, the production cycle will be increased. And if the time was too short, the product yield will be decreased.
- Optimum temperature and time of drying stage
If the temperature was higher than the boiling point of acetic acid, large amount of the unreacted acetic acid will be discharged into atmosphere during the drying stage. If the temperature was lower than 30 ℃, the drying time will be too long. So the temperature was fixed between 30 and 40 ℃, and the drying time was fixed at 7.5 h.
Basic Res. Food Sci.
Chem. Eng. Prog.
J. Chem. Eng.
Chem. Ind. Eng. Tech.