Absorbent vs Adsorbent

by Andy on April 22, 2013

Absorbent SwabWhen looking at cleaners like swabs and wipes you may notice that some are advertised as absorbent or adsorbent. The change between the “B” and the “D” is not a regional spelling change or a typo, it actually signifies how the material interacts with the substance it is supposed to pick up. The difference between absorbent and adsorbent is subtle, but very necessary to take into account when choosing a swab or wipe.

A material is absorbent when it pulls the substance into itself. For absorbent think of a sponge that can soak up water. The major benefit of absorbent materials is that they can soak up a lot more than their starting volume, and have low vapor release compared to adsorbent materials.

Adsorbent materials only attract the substance onto the surface of the object, coating the adsorbent material in the substance. Common adsorbents are activated carbon in water filters and desiccating silica gels. Because adsorbent materials are coated in the substance it is more efficient to have a lot of small adsorbents than a large one, as that increases the surface area. This is why there are typically a lot of small balls of silica in desiccant packages.

Typically, adsorbent and absorbent materials are used for different situations, so the one you need depends on your intended use. If you just need to soak up liquids, then an absorbent sponge would be appropriate; but if you need to filter that liquid then you would use the adsorbent activated carbon. Overall, adsorbent materials are cheaper than absorbent ones that do the same job, but absorbent materials can pick up more than adsorbent ones. As always, consult the manufacturer of your absorbent or adsorbent materials if you have a specific question on their exact intended use.

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