Under the appearance of white feathers, sodium polyacrylate & potassium polyacrylate are both called “superabsorbent polymer”. Both of them have powerful water-absorbent abilities.
Differences between sodium polyacrylate and potassium polyacrylate
|chemical name||sodium polyacrylate||potassium polyacrylate|
|usages||the absorbent material of diapers, sanitary napkins, etc.||water-retaining agent for plants|
|appearance of absorbing||white powder => white water gel => transparent water gel||white powder => transparent water gel|
|the water-retaining ability of water gel||strong than roots of plants||weaker than roots of plants, strong than soil|
|decomposition time||in one week||more than two weeks|
|decomposition product||Na+, carbon dioxide, water, etc.||K+, carbon dioxide, water, etc.|
Does sodium polyacrylate help plants?
Sodium polyacrylate is widely used in every aspect of our life. And we can easily get sodium polyacrylate from paper diapers, sanitary napkins, etc.
Can we use sodium polyacrylate as a water-retaining agent for plants instead of potassium polyacrylate?
The answer is obviously no.
- No water releasing function. Different from potassium polyacrylate, sodium polyacrylate (water gel) won’t release water to plants.
- Bad for soil. Sodium polyacrylate will be decomposed into sodium salt which causes soil salinization.
How to devise them? (especially used in agriculture)
As sodium polyacrylate is much cheaper than potassium polyacrylate, some profiteers sell sodium polyacrylate as the water-retaining agent.
So we need to devise them before purchasing.
The simplest method is the sunlight test:
Expose the water gel to the sun, sodium polyacrylate (or low-quality potassium polyacrylate) water gel will melt in 7 days.