Activated Carbon Adsorption

Activated carbon is used for the removal of odors, tastes, colors, or even poisons in either a liquid or gas state. The ability for activated carbon to remove contaminants is not based on how much carbon one uses, but rather the capacity of carbon to adsorb the contaminant. The higher the capacity, the greater amount of contaminants the carbon adsorbs per unit volume. Because natural carbon is not able to treat every contaminant, there are different carbon products which remove specific contaminants.

In a specific case, activated carbon can remove certain chemicals or contaminants from water. It is most effective in the removal of organics due to their composition of hydrogen and carbon. Therefore, the activated carbon has a much greater attraction to the contaminant than the contaminant has with the water.1 This causes the activated carbon to adsorb the contaminant, leaving the water pure and contamination free. However, there are still organics that are poorly adsorbed by activated carbon.

When unsure if a chemical can be removed by activated carbon, both the molecular weight and solubility of the chemical are factors to be aware of. Compounds that have high molecular weight and low solubility are more effectively adsorbed by activated carbon. “The reason for these properties is that the adsorption is best for compounds with similar molecular structures and electron distribution as the adsorbent material.”2 In other words, because activated carbon has a high molecular weight, it effectively adsorbs materials with these same properties.

Chemicals with a low molecular weight such as hydrogen sulfide, ammonia, and chlorine are poorly adsorbed by activated carbon in the vapor phase regardless of its organic properties. For these instances, General Carbon offers GC IPH or GC Sulfursorb Plus to remove hydrogen sulfide, GC IPA to remove ammonia, and GC Chloratreat to remove chlorine. Although standard activated carbon may not be able to remove certain contaminants, General Carbon has many specialty vapor and liquid filtration products for these problematic applications.

There is not one type of carbon that can remove every single contaminant. As a result, if multiple chemicals need to be removed, General Carbon can provide a blend of various products that each remove a specific contaminant. For example, if someone needed to remove H2S as well as various nuisance odors, then GC Sulfursorb Plus or GC IPH can be blended with GC 4x8S to remove both groups of contaminants. If you should have any questions about any of our products please do not hesitate to contact us.

Sources:

1 – Activated Carbon Filtration by Frank DeSilva

2 – Cleaner production: Technologies and Tools for Resource Efficient Production by Lennart Nilsson

3 – Drinking Water Treatment: Activated Carbon Filtration by Bruce I. Dvorak and Sharon O. Skipton  http://www.ianrpubs.unl.edu/epublic/live/g1489/build/#target2