Activated carbon can be classified in two different ways. One is the type of raw material used to produce it, while the other is the specific form in which it is produced. Together, the raw material and its final form create individual types that are ideally suited to different applications due to their unique pore structure, size, and shape. Additionally, all types of activated carbon can be impregnated, or treated with chemicals to improve their suitability for specific applications.
What Is Activated Carbon?
Activated carbon is made from organic material with a high naturally occurring level of carbon. Peat, coal, wood, and coconut husk are extremely common Activated carbon has a tremendous ability to adsorb and remove a wide range of organic and inorganic contaminants.
Virtually any organic material that is high in carbon can be made into activated carbon. However, the majority of activated carbon comes from three main sources:
Wood or Peat: The pore structure of wood and peat-based activated carbon is primarily macro porous. This makes it ideal for removing large molecular compounds.
Coconut Shell: Coconut shell-based activated carbon is primarily microporous. This gives the activated carbon a high adsorption energy, making it perfect for removing contaminants of low molecular weight.
Coal: The pore structure of coal varies depending on the type of coal that is used. However, its pore structure will fall somewhere between wood or peat and coconut shell. This makes it an excellent general purpose solution, as it can handle virtually any application that does not require a very precise pore structure.
Forms of Activated Carbon
Activated carbon is processed into three main forms. Each is best-suited to specific types of applications.
Powdered activated carbon (PAC): Powdered activated carbon consists of fine particles capable of passing through an 80-mesh sieve. Due to its small particle size and tendency to create dust, it is generally used as part of a processing machine such as a filter rather than alone. It can also be pre-wetted to control dust, or mixed with other compounds into an extruded water dispersible pellet. PAC is particularly suited to applications with a high flow rate, such as controlling the taste and smell of drinking water. PAC cannot be recycled, so it is not the best choice for applications that use a great deal of activated carbon.
Granular activated carbon (GAC): The next size up, granular activated carbon has a proportionately smaller external surface area than PAC. Smaller GAC is particularly suited to liquid phase applications, while larger GAC is better for vapors and gases. GAC is recyclable, making it advantageous over PAC for applications that use a lot of activated carbon.
Extruded activated carbon (EAC): PAC or powdered char can be mixed with a binder and formed into cylindrical pellets known as extruded activated carbon. Activation catalysts can also be added to develop a specific pore structure. EAC creates only minimal dust, and has a very high mechanical strength but a low pressure drop, making it ideal for gas phase applications.
Activated carbon’s pore structure, size, and shape greatly influence the applications for which it is best suited. The raw material and the form work together to create a specific type, and each specific type is ideal for certain applications. In addition, all types of activated carbon can be impregnated with various chemicals to improve their ability to remove specific targeted compounds.
Are you interested in purchasing activated carbon for a specific application? Do you require expert guidance in choosing the right impregnation for your needs? With more than 70 years of experience in the activated carbon industry, Oxbow Activated Carbon is proud to provide the most diverse line of activated carbon products on the market today. We provide both standard and custom impregnations, spent carbon disposal and reactivation, and numerous other specialized services. We pride ourselves on our individualized customer service, and we look forward to becoming your one-stop shop for all your activated carbon needs.