Activated Carbon | Detailed overview

Redaction • 14 maart 2021

Activated carbon (also called activated coal or activated charcoal) is a special type of carbon that can adsorb various molecules from both liquid and gas phase. In this blog we will dive in the world of the purification technique activated carbon. We will discuss the following themes;

What is activated carbon?
How does activated carbon work?
What are the benefits of activated carbon?
What are the disadvantages of activated carbon?
What can be removed with activated carbon and from what can this be removed?
What is a activated carbon face mask?
Activated carbon and quality standards

“One gram of activated carbon has an surface area that can be as large as a football field ”

What is activated carbon?

Activated carbon is a special type of carbon that can adsorb various molecules and these are adsorbed in the large surface area by van der Waals forces. A gram of activated carbon has a surface area that can be as large as a football field, this means a surface area of 500 to 2000 m2/g and sometimes even more. The surface area of activated carbon is divided into micro, meso and marco pores.

Micropores r < 1 nm (nm = nanometer)
Mespores r 1-25 nm
Macropores r > 25 nm

Activated carbon occurs in different particle sizes and also in different forms:

PAC = Powder Activated Carbon

GAC = Granular Activated Carbon

EAC = Extruded Activated Carbon

SAC = Sperical Activated Carbon

GAC, EAC and SAC are often used in an activated carbon filter. This can be for example an activated carbon air filter or activated carbon water filter.

An important parameter for various applications is the density of activated carbon; learn more in this blog; activated carbon density.

Next to above also activated carbon cloth, activated carbon fibers, activated carbon honeycombs, activated charcoal pills and activated carbon blocks can be seen as a separate shape or type.

The activated carbon (activated charcoal) definition according to the dictionaries:

"Highly absorbent carbon obtained by heating granulated charcoal to exhaust contained gases, resulting in a very porous form with a large surface area. It is used chiefly for purifying gases by adsorption, solvent recovery, or deodorization and as an antidote to certain poisons. Also called activated carbon."

Source: https://www.yourdictionary.com/activated-charcoal#americanheritage

"A form of carbon having very fine pores: used chiefly for adsorbing gases or solutes, as in various filter systems for purification, deodorization, and decolorization."

Source: https://www.dictionary.com/browse/activated--charcoal

How is activated carbon made?

Activated carbon can be made through various processes and from various carbon-containing raw materials.Often raw materials such as, coal, brown coal, charcoal or coconut shells are used. There are also none natural resources that are used to make synthetic activated carbons.After the raw material comes the activation process, the best known process is the steam activation process which involves a carbon source which is first carbonized and then activated at around 1000 degrees with steam. Another process is chemical activation involving chemicals, for example phosphoric acid, a raw material is impregnated and then activated at around 500 degrees.

How does activated carbon work?

Activated carbon has through the micro, meso and macro pores have a selective adsorption capacity which works by the van der Waals forces. Activated carbon therefore works on the basis of adsorption (ie not absorption). When using activated carbon in, for example, water or gas or air the molecules that one wants to remove eventually end up via diffusion in the pore structure of the activated carbon where the adsorption takes place.

Another option is to impregnate activated carbon with chemicals (minerals, metals, etc) and use the large surface area in combination with the chemicals for chemicalsorption or catalytic processes.

What are the benefits of activated carbon?

Very high removal capacity for organic components
Cost-effective product, good price performance
Reuse, in some cases activated carbon can be reactivated and reused

What are the disadvantages of activated carbon?

Non-selective removal for certain molecules
Impurities (eg Metals or minerals) can leach out into a liquid
Black dust

What can be removed with activated carbon and from what?

Activated carbon is the champion in the amount of purification applications. Think of applications as below;

Medicine, removal of colors or removal of toxic substances.
Potable water or wastewater purification
Removal of mineral oil
Removal of PFAS (PFOA, PFOS)
Removal of BTEX
Removal of poly aromatic hydrocarbons (PAHs) and removal of phenols.
Process industry, removal of dioxins and polychlorinated biphenyls.
Removal of colors and removal of odors.
Fruit juices, removal of phenols and removal of patoline
Sugar, removal of color
Biogas, removal of VOCs and removal of H2S or siloxanes
Flue gas, removal of dioxins
Flue gas, removal of mercury
Water, removal of contaminants of emerging concern (CECs)

What is a activated carbon face mask?

The corona virus (COVID) is a thing that you want to avoid and one off things that is used, for reducing the risks, are face masks. There are various types of face masks like, pm 2.5 activated carbon filters, N95 masks, FFP1, FFP2 and FFP3 masks. Some will contain activated carbon, and some not. What is important, when you buy such a mask, is that you understand for what you buy it for, is it for particles only or also removal off other things like viruses. Our advice; Check carefully what you buy, where you buy it and if it is single use or can be used multiple-times.

The activated carbon face mask does of course contain activated carbon. The activated carbon containing mask can potentially remove various contaminants from the air and adsorb these in the pore structure of the carbon like described above. The face masks often contain out of various layers of fabrics and a layer that has powder activated carbon in it.

Activated carbon and quality standards

Follow the link to our separate blog about " activated carbon and quality standards".

We have discussed in this blog the purification technique activated carbon. We have discussed the following themes what is activated carbon, how does activated carbon work, how does it become activated carbon and what are the advantages and disadvantages of activated carbon and what can be removed with activated carbon. Also read our other and future blogs about various purification techniques.

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