We made several test of sodium alginate colloidal precipitation. In all test we were not able to obtain the sodium alginate precipitate in droplets, grain or powder form, we always obtain sodium alginate precipitate in fluffy, sticky filament/string form, where said sodium alginate fluffy, sticky filament/string tend to stick to the mixing tank stirrer forming a fluffy ball. This happens both at lab scale beaker and in pilot scale where we inject sodium alginate aqueous colloidal solution (pH = 10,5) together with azeotropic ethanol (ratio ethanol-colloidal solution = 2) with a coinjection nozzle directly into an high shear fristam pump. How can we run the precipitation not to obtain filament. We know that in industry sodium alginate precipitation occurs in controlled mixing tanks wher pH is controlled to avoid filament formation like in our lab. Can anybody give a suggestion? Are there any paper or patent that describes sodium alginate colloidal solution precipitation step?
Giuliano Cavaglià
I can recommend the main methods to eliminate the formation of threads. Maybe you have already tried them and therefore will reduce the new experiment.
1. Improving the homogenization of the solution:
Alginate should be well soluble in water before adding calcium salt. To prevent the formation of threads, it is recommended to thoroughly mix the alginate solution mechanically (for example, using a disperser or colloid mill).
2. Using low-molecular forms of alginates:
High molecular weight of alginate increases the viscosity of the solution and promotes the formation of threads. The use of low-molecular fractions of alginate reduces the risk of the appearance of thread-like structures.
3. Control of reaction conditions:
The rate of addition of calcium solution affects the formation of threads. Slow dosing of calcium ensures uniform distribution of calcium cations, preventing the formation of threads.
4. Adding surfactants:
Some surfactants can help reduce the adhesion between alginate molecules, reducing the likelihood of thread formation.
5. Pre-treatment with potassium phosphate solution:
Treating the surface of the solution with phosphates helps reduce the concentration of free calcium ions, promoting better distribution of ion exchange processes and reducing the risk of thread formation.
To precipitate sodium alginate colloidal solution into powder or granular form:
- Badges
- Science method
- Similar topics
- Biological Science
- Ecology