30 Purchasing Questions about Super Absorbent Polymer

Hi everyone, my name is Simon Dou – the Wiki Entry Creator of Potassium Polyacrylate(user name is “Doufenglai”).

It has been several years since I finished writing “The Ultimate Guide to Super Absorbent Polymer”. During this period, many people asked me questions about this amazing material. So I want to use this article to answer the questions that everyone is most concerned about.

Since this article is long and will be updated continuously, if you are interested in SAP (Super absorbent polymer), it is recommended to bookmark it. (press “Ctrl”+”D” to add bookmark)


What’s Super absorbent polymer (SAP)?

The earliest SAP was invented by the United States Department of Agriculture (USDA) in the early 1960s. Its role is to improve the water holding capacity of the soil.

Because the water-absorbing materials at that time still stayed on fiber-based materials. Soon SAP replaced most absorbent materials (like tissue paper, cotton, sponge, and fluff pulp) with its excellent water absorption capacity and water retention capacity, and was used in all aspects of life.

Chemical composition

There’re two types of superabsorbent polymers:

  • Sodium polyacrylate,
  • Potassium polyacrylate.

Therefore, we divide all questions into questions about sodium polyacrylate and questions about potassium polyacrylate.


Sodium polyacrylate VS Potassium polyacrylate

Due to the difference in chemical composition and production process, the two types of SAP products are very different.

Let’s talk about the difference in detail from multiple dimensions:

Chemical formula

Sodium polyacrylate: [−CH2−CH(CO2Na)−]n.
Potassium polyacrylate: [−CH2−CH(CO2K)−]n

Product use

Potassium polyacrylate: Used in agriculture as a soil water retention agent.

Sodium polyacrylate: Applied to all aspects of life (90% used in paper diapers production as the absorption material).

Price

Generally speaking, the price of potassium polyacrylate is about 2.5-3 times that of sodium polyacrylate.

Such a huge difference in price comes from the difference in production capacity between the two: The market demand for potassium polyacrylate, which is only used for agriculture, is far less than that of sodium polyacrylate, which is used in all aspects.


Questions about Sodium Polyacrylate

What’s the melting point?

It’s 150℃.

In addition, after sodium polyacrylate absorbs water and becomes a hydrogel, it will be easily melted and photodegraded at a lower temperature (such as 40°C). This is one of the reasons why sodium polyacrylate cannot be used as a water-retaining agent for agriculture and forestry.


What’s the Ph value?

Generally speaking, sodium polyacrylate is weakly acidic because it has very little acrylic residue. (Sodium polyacrylate is formed by the polymerization reaction of acrylic acid and sodium hydroxide. )


What’s the water absorption?

As the strongest water-absorbing material at present, sodium polyacrylate can absorb up to several thousand times its own weight of pure water.

In addition, whether the water is pure or not directly affects the absorption of sodium polyacrylate. If salt is added to the water, the water absorption will be greatly reduced. The concentration of water ions in the soil is extremely high, and the water absorption of sodium polyacrylate is greatly reduced — This is one reason why it is not suitable for use as a water-retaining agent.


Why does sodium polyacrylate absorb water?/how does sodium polyacrylate work?

You may have been wondering how does sodium polyacrylate work. In fact, the entire water absorption process has undergone complex physical and chemical reactions.

Simply speaking, there are network molecular chains in the molecular structure of A. It electrolysis occurs immediately after encountering water and dissociates into positively and negatively charged ions. The positively and negatively charged ions have a strong affinity with water. Therefore, it has strong water absorption and water retention capabilities.


How is sodium polyacrylate manufactured?

Many people ask me “is sodium polyacrylate natural?”. We need to know the sodium polyacrylate’s manufacturered process first.

How to make sodium polyacrylate?

There’re four ways to produce sodium polyacrylate: Copolymer chemistry, Gel polymerization, Solution polymerization, and Suspension polymerization.

Here’s the common process picture for your conference:

As you see, sodium polyacrylate is not a natural product.

tip: there is a sodium polyacyrlate produced by starch grafting. The manufacturer claims that it is a “natural product” as a gimmick.

In theory, sodium polyacrylate can be applied to all applications that need to absorb water or lock water. But as mentioned before, it cannot be used for agricultural water retention. This will be explained in detail later.

Current application list of sodium polyacrylate

Sodium polyacrylate can absorb a lot of liquid & lock it firmly.

So it can be used in:

  • paper diapers;
  • sanitary napkins;
  • nursing pad.

Sodium polyacrylate becomes a stable gel after absorbing water.

So it can be used in:

  • ice bag;
  • hot/cold gel pack;
  • growing toys;
  • Fragrance carrier;

Sodium polyacrylate’s hydrogel formed after absorbing water can block water.

So it can be used in:

  • water blocking tape in cable;
  • Water swelling sandbag for flood control.

Sodium polyacrylate’s hydrogel can be made in colorful and into a spherical shape.

So these sodium polyacrylate beads/balls can be used in:

  • Toy gun bullet;
  • Transparent vase interior decoration;

Sodium polyacrylate can quickly turn liquid into solid for easy collection and processing.

So it can be used in:

  • Human or animal feces and urine collection;
  • Wastewater treatment;

Sodium polyacrylate can be modified in the production process.

So it can be used for some special purposes like:

  • Artificial snow.
  • Fire-retardant gel.
  • Additives for drilling lubricants.
  • Concrete protection. It can effectively prevent the concrete from drying out during the solidification process.

Some uses that have not been widely used or proven:

  • Water bed;
  • Thickening agent;
  • Drown-free water source for feeder insects.

Is sodium polyacrylate OK in food?

Although the claim of “food grade sodium polyacrylate” has existed for many years, no manufacturer has claimed to be able to produce it. This may be related to the production process.


Is sodium polyacrylate toxic to dogs/animal/insect?

Strictly speaking, the answer can be yes only if sodium polyacrylate meets the food-grade standard.


Where to find/get sodium polyacrylate at home?

As I said, you can easily find sodium polyacrylate in sanitary napkins or paper diapers.


Is sodium polyacrylate safe/good for skin?

Although sodium polyacrylate is not toxic, there’re extremely strict requirements on technical parameters especially used in hygiene products like diapers, sanitary napkins, nursing pads.

As a manufacturer of hygiene products, it’s necessary to check out the MSDS (Material Safety Data Sheet) of sodium polyacrylate.

As a customer of hygiene products, please try to choose well-known brand products.

note: acrylic acid content is a very important indicator. It may cause skin allergies and rashes when the content exceeds the standard.


Is sodium polyacrylate safe for plants (as fertilizer)?

Although the price of sodium polyacrylate is much lower than potassium polyacrylate, it’s whimsical to use it as a water-retaining agent.

List a few reasons why you should NOT use sodium polyacrylate for plants:

  • As a water retaining agent, sodium polyacrylate can hardly absorb water underground cause the high ion concentration soil leachate.
  • The water gel from sodium polyacrylate is easily melted and photodegraded at a lower temperature (such as 40°C).
  • Sodium polyacrylate is decomposed into a large amount of sodium ions that cannot be absorbed by plants, which leads to increased soil salinization.

Note: different from A, B, which is specially designed for the water-retaining agents, effectively solves the above three problems.


Can sodium polyacrylate go down the drain?

Yes for sodium polyacrylate gel. It’ll slowly be decomposed into the water, carbon dioxide, and some sodium ions, which will not cause environmental pollution.

tip: Sodium polyacrylate powder has a strong water swelling property. This will cause the toilet to block.


Where can buy sodium polyacrylate?

Purchase sodium polyacrylate bulk.

For bulk purchasing, usually, the minimum purchase quantity of the supplier is 500KG.

A simple Google search will find that SOCO is one of the most professional suppliers of this product.

You can contact them via: www.sapgel.com.

Purchase sodium polyacrylate online

You may only need 500g or 1kg sodium polyacrylate for some scientific experiments.

Then you can consider purchasing it from Amazon.


Questions about Potassium Polyacrylate.

What is potassium polyacrylate used for?

Potassium polyacrylate is a kind of super absorbent polymer used for agriculture. It can improve soil

Mixing it in the soil can greatly increase the water holding capacity of the soil.


Can potassium polyacrylate be reused?

Yes. Potassium polyacrylate becomes gel form after absorbing water. After gel releases the water to the roots of the plant, it will return to the granular state. There potassium polyacrylate granular can absorb rainwater or irrigation water again.

The life of potassium polyacrylate in the soil is related to the degree of soil salinity and local temperature. It can usually reach several years.


Is potassium polyacrylate safe for the environment (biodegradable)?

Yes. Unlike sodium polyacrylate, potassium polyacrylate can be decomposed into water, carbon dioxide, and potassium that can improve soil and increase fertilizer efficiency.


How to use potassium polyacrylate for plants?

You can make the potassium polyacrylate gel first then mix it with soil.


Where can buy potassium polyacrylate?

Purchase sodium polyacrylate bulk.

For bulk purchasing, usually, the minimum purchase quantity of the supplier is 500KG.

A simple Google search will find that SOCO is one of the most professional suppliers of this product.

You can contact them via: www.sapgel.com.

Purchase sodium polyacrylate online

You may only need 500g or 1kg sodium polyacrylate for some scientific experiments.

Then you can consider purchasing it from Amazon.


References