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What is Adsorption?

The ocean adsorbs carbon dioxide from the atmosphere.
Adsorption has been used to purify drinking water.
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  • Written By: S. Mithra
  • Edited By: L. S. Wynn
  • Last Modified Date: 15 November 2014
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Adsorption is a process, similar to absorption, by which a substance in a gas or liquid becomes attached to a solid. The substance can be a pollutant, called an adsorbate, which is attracted to the surface of a special solid. Adsorption occurs naturally, but industrialists have perfected adsorption methods to clean up hazardous waste or purify drinking water.

Tiny chemical particles suspended in another phase of matter, meaning in the air as a gas or in water as a liquid, are sometimes considered contaminants. These tiny particles can be separated from that phase, called the adsorbent, to enter a different phase. A material of another phase, like the solid carbon, preferentially targets these particles and bonds the adsorbate to its surface. The remaining air or liquid has been purified. This differs from absorption where the particles never change phase, but enter pores of the solid along with the accompanying air or water.

Natural or organic methods of adsorption take place all the time. For example, the ocean adsorbs carbon dioxide in the atmosphere, which effects climate and atmospheric temperature. Early humans observed that if they charred a piece of bone all the way through, they could put the bone in food mixtures, like sugar water, and it would collect polluting particles that weren't edible, thereby purifying the food. Particles colored in our visible spectrum, as well as those with strong odors, are easiest to adsorb.

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It's important to harness the power of adsorption in battling modern chemical hazards. Some solids are ideal for adsorption. They have a lot of surface area for their volume because they are pockmarked with micropores. Industrial and commercial uses for adsorption filters vary. For example, carbon makes cold drinking water taste better. A carbon filter can be heated to clean the surface of adsorbates and reused. Activated alumina removes harmful chemicals like fluoride and arsenic from liquids. Synthetic resins can clean up highly hazardous spills, such as nerve gas, in areas that might have high temperatures, like near explosives.

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goldapp
Post 13

Some nanomaterials have adsorption characteristics, like sieve, catalysts, carbon black etc. People usually use gas adsorption as a way to determine these materials' specific surface area, pore size, pore volume, adsorption and desorption isotherms. etc. Currently, the popular one is V-Sorb 2800P to test these parameters.

jholcomb
Post 11

@rugbygirl - I do think that Latin roots are in there, but not as clearly as with, say, the adductor and abductor muscles of the thigh. "Sorb" apparently means "to suck in."

So you can think of it this way: When something is absorbed, it is sucked in from the outside and ceases to exist. When something is adsorbed, it is sucked in to the surface, no further. Hope that helps!

rugbygirl
Post 10

I'm not clear on how adsorption, by definition, is different from absorption. I know that in Latin, the root "ad" means "to" while "ab" means "away from." That's why when you abduct something, you take it away. Does that root difference come into play here?

mohsin1khan7
Post 9

Also tell about the application and advantages and disadvantages of adsorption and where it is used.

anon77605
Post 6

explain about application of adsorption.

anon59412
Post 5

Would you explain about applications of adsorption?

zambik
Post 4

hi!

where are the adsorption techniques used??

thanks...

adolphanga
Post 3

Dear sir/madam, would please tell me how the adsorption may be used to recover precious metals with adsorbent as carbon nanotubes?

anon2774
Post 1

as we are saying that macropore space must be equal with a micropore space why is the case?

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