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What are Volatile Organic Compounds?

March 26, 2024

Organic chemical materials are found everywhere in the environment because they have become essential ingredients in many products and materials.

Volatile organic compounds (VOCs) are the vapours of organic chemical compounds which are a large class of substances that include complex substances used as solvents and hydrocarbons. Many of these have a low boiling point which makes it possible for them to evaporate under normal indoor atmospheric conditions of temperature and pressure, therefore becoming a volatile chemical.

Why Are VOCs A Concern?

Many manufacturing operations such as the production of chemicals, pharmaceuticals, or coating or printing processes, use these organic compounds as solvents or reactive chemicals. In the exhaust airflows from these production processes, they easily evaporate or vaporise and can be released into the exhausted air as Volatile Organic Compounds (VOCs).

Many waste-handling processes also release these VOCs into the air. In addition, inside buildings, such vapours can also be released into the air from the use of products and materials containing VOCs.

VOCs are therefore of a concern as both indoor and outdoor air pollutants as there is the potential for VOCs to adversely impact human health from their exposure. In the wider environment, they can create photochemical smog under certain conditions.

European Emission Regulations

The European Union continues to work on bringing pollution down to levels that are no longer harmful to health by setting stronger rules to tackle pollution at source with a planned revision of the directive on industrial emissions (IED) and the regulation on the establishment of an industrial emissions portal (IEP).

This new Industrial and Livestock Rearing Emissions Directive 2024/1785 (IED 2.0) has just been published. It is to be the main EU instrument to reduce emissions and prevent waste generation from large industrial installations and intensive livestock farms (pig and poultry). It amends Directive 2010/75/EU. 

The overall aim of the IED 2.0, which entered into force on 4 August 2024, is to minimise the impact of pollution on people’s health and the environment with the objectives to streamline permitting via the new Industrial Emissions Portal Regulation, which will enhance access to environmental data.

VOCs and Activated Carbon

As VOCs are organic, this means that most of them are readily adsorbed onto activated carbon. Adsorption is the process by which these gaseous molecules are attracted and concentrated on the carbon surface where they are bound or adsorbed into the pores of the activated carbon.

VOCs can therefore be effectively removed from the air with activated carbon and in most cases, the activated carbon can be recycled by reactivation for reuse. The ability to reactivate or recycle activated carbon makes it a cost-effective and sustainable solution to remove VOCs from the air.

There is a series of EU reference documents on Best Available Techniques (BREFs) developed to describe industrial processes and the best available techniques for controlling pollution from industrial activities of which adsorption on activated carbon is one of them.

The ‘’Common Waste Gas Management and Treatment Systems in the Chemical Sector’’ and the ‘’ Surface Treatment Using Organic Solvents including Wood and Wood Products Preservation with Chemicals’’ are two such lengthy policy reference reports relating most to VOC emissions from Industrial processes.

What Volatile Organic Compounds Can Be Removed Using Activated Carbon?

Activated carbon, in all its forms, has excellent adsorption capacity for a wide range of VOCs from air. However, for the most effective impurity removal, different carbon types may be required, depending on the combination of pollutants such as if it is an organic or inorganic impurity or compound. Many of these pollutants can also be effectively removed from gaseous streams other than air such as Nitrogen or Carbon Dioxide (CO2).

Some of the typical volatile organic pollutants that can be effectively removed from the air using activated carbon include the following:

Acetic acidDichloromethane (DCM) / Methylene chlorideNitriles
Acetone1,4-DioxaneOctane
AcetamideDioxinsOdour
AcetonitrileEpichlorohydrinOrganic Vapour
AcroleinEstersOzone
AcrylateEthanolPentane
Acrylic acidEthersPentanol
AcrylonitrileEthyl acetatePentene
AlcoholsEthyl acrylatePFAS
AldehydesEthylbenzenePhenol
Aliphatic CompoundsEthylene dichloride(alpha) Pinene
AlkanesEthylene oxide Propane
Amides Glycol ethersPropanol
Amines Halogenated HydrocarbonsPropionaldehyde
AnilineHeptanePropylene
Aromatic CompoundsHeptanolPropylene Oxide
BenzeneHeptenePyridine
BTXHexaneShellsol
1,3-Butadiene HexanolSiloxanes
Iso-butaneHexeneSolvents
ButaneHydrocarbonsStyrene
ButanolIsopropyl acetateTars
Butyl acetateIsopropyl alcohol/isopropanol (IPA)Terpenes
Carbon TetrachlorideKetonesTetrachloroethane
Chlorine (CL2)d-LimoneneTetrachloroethylene/ Perchloroethylene (Perc)
Chlorinated Solvents MethanolTetrachloromethane
2-Chloro-1,3-butadieneMethyl acetateTetrahydrofuran
ChlorobenzeneMethyl acrylateToluene
ChloroethaneMethylamineToluidine
ChloroformMethyl chlorideTrichlorobenzene
ChloromethaneMethyl ethyl ketone (MEK)Trichloroethane
ChloropropaneMethyl isobutyl ketone (MIBK)Trichloroethylene (TCE)
CresolMethyl isocyanateTrichlorofluoromethane
CumeneMethyl MercaptanTrichloromethane
CycloalkanesMethyl methacrylateTriethylamine
CyclohexaneMethyl tert-butyl ether (MTBE)Trimethylbenzene
CyclohexanoneMineral SpiritVinyl acetate
DichlorobenzeneNaphthaleneVinyl chloride
DichlorodifluoromethaneNitrobenzeneVolatile Organic Compound (VOC)
DichloroethaneNitrotolueneXylene
Dichloroethylene (DCE)  

For those pollutants of an inorganic nature, such as Ammonia or are difficult to remove using simple activated carbon such as Formaldehyde, the activated carbon’s adsorption ability can be enhanced by a chemical treatment to generate an impregnated carbon.

For other pollutants of a more specialised or inorganic nature, see our ‘’What are Air Pollutants’’ article or “Respirator Protection” article.

How can we help?

The most effective carbon to be used for a particular application-specific type may depend on the nature of the exhaust air to be treated, the plant operating process conditions, the contaminants to be removed and the emission levels that the cleaned exhaust air needs to meet.

If this is required for a new treatment process, why not consider the use of a mobile carbon filter. These are activated carbon filters that can be both used on-site as a VOC purification vessel and then transported to and from the site, without the need for any on-site carbon exchange. These mobile carbon filters are supplied on a lease basis so there is no need for an expensive capital commitment for a fixed abatement system.

If you need help with the choice of activated carbon, the help of our mobile carbon filter service or just some further advice, please contact us – contact our technical team.