What’s sodium polyacrylate?
Sodium polyacrylate is a white granular or powder polymer which looks like sugar.
As a kind of super absorbent polymer (SAP), it has strong absorbency for hundreds of times its own weight in water.
After absorbing water, it turns to a water gel form which locks water firmly.
Information Form
| Chemical formula | (C3H3NaO2)n |
| Density | 1.22 g/cm3 |
| CAS Number | 9003-04-7 |
| ECHA InfoCard | 100.118.171 |
The safety of sodium polyacrylate
For human
As we know, it is the main absorbent material in baby paper diapers.
Now we’ll talk about safety when it touching our skin.
Acrylic acid
Acrylic acid may be the only substance in sodium polyacrylate that can irritate and hurt the skin.
Sodium polyacrylate is consists of acrylic acid and sodium hydroxide. As this is not a complete reaction, there would be few acrylics acid left.
The key is how much is acrylic acid left.
As a leftover from the manufacturing process, the acrylic acid value should be less than 300 PPM for safe, especially for paper diapers, nursing pads, sanitary towels, etc.
For your reference, here’s a material safety data sheet (documents created by SGS), sodium polyacrylate is totally safe.
Other safety factors
As a Super absorbent material, it can also cause certain dangers if not handled properly.
- It may irritate the lungs when you inhale tiny sodium polyacrylate powder;
- It can expand quickly when meeting water. So, please do not eat it;
- After absorbing, it turns to water gel form – which is slippery and will cause serious clogging.
Conclusion
Sodium polyacrylate is safe for humans. It’s non-toxic and free from any major safety risks.
For environment
As we know, potassium polyacrylate, another kind of super absorbent polymers, can be used as the water-retaining agent for plants.
And it can be broken into urea, carbon dioxide, water, and potassium.
So, what about sodium polyacrylate?
Decomposition product in the soil
Sodium polyacrylate can be broken into urea, carbon dioxide, water, and sodium.
And the problem is sodium.
In general, small amounts of sodium won’t affect the soil and harm the natural environment.
But that’s different when we frequently put plenty of them into the soil – which would cause salty groundwater to rise towards the surface and contaminate soils.
No working at all
Actually, sodium polyacrylate can’t keep retaining water at all. There’re too many differences between it and potassium polyacrylate in the soil.
It:
- can only absorb a few of water in the soil because of the metallic ion concentration of soil extract;
- would melt in one month after absorbing water becoming gel form.
Conclusion
It’s unwise to use Sodium polyacrylate as the water-retaining agent. It’s no working and would cause salinization of soil.
