Activated carbon is one of the most versatile and effective adsorbents used globally in purification, filtration, and remediation applications. Its success hinges not just on the raw material and activation process, but also on mesh size and particle size — two often misunderstood but critically important specifications for performance and system design.
At General Carbon, we have a deep understanding of how differences in mesh sizes can affect the performance of industrial adsorption systems. In this comprehensive guide, we define the mesh and particle sizes of activated carbon and explore how and why different sizes affect different treatment systems.
What Is Mesh Size?
Mesh size is a way of describing how big or small the pieces of activated carbon are. It’s based on how carbon particles move through standardized screens, also called sieves. Mesh sizing is crucial because it standardizes particle ranges so customers can compare media across manufacturers and select the right type for their application.
A designation like 12×40 mesh means that the carbon particles are small enough to pass through a screen with 12 openings per inch but are retained by a screen with 40 openings per inch. In other words, the first number indicates the largest mesh opening a particle will pass through, while the second number indicates the smallest.
When a product says that 90% of particles fall within a certain mesh range, it means the carbon is carefully sized so most pieces are neither too large nor too small. This consistency helps ensure predictable performance in filtration systems.
For example, our GC 12×40 and GC 12×40SAW products show a mesh range where 90% of the particles fall between the openings (also called apertures) of a No. 12 and No. 40 screen, with strict limits on particles outside that range.
What Is Particle Size?
While mesh size is based on sieve measurements, particle size describes the actual physical size of each granule of activated carbon. For granular activated carbon, particle size is usually expressed using mesh numbers. For other forms, like pelletized or extruded carbon, particle size may be listed in millimeters instead.
For instance, our pelletized activated carbon GC C-40 has a mean diameter of 4.0 mm, reflecting its cylindrical shape rather than a mesh range.
Even though mesh size and particle size are measured differently, they describe the same basic thing: how big each piece of carbon is, and how it will behave in a system.
Why Carbon Size Matters
The size of activated carbon particles affects how quickly contaminants are removed, how easily water or air flows through the system, and how long the carbon lasts before needing replacement. Let’s take a closer look at why carbon size matters.
Surface Area and Adsorption Efficiency
Activated carbon works by attracting and holding contaminants on its surfaces and inside tiny pores. Smaller particles (higher mesh numbers) have more surface area exposed and allow contaminants to reach pores more quickly, which can improve removal speed. Larger particles (lower mesh numbers) may work more slowly but can still be very effective when given enough contact time.
Pressure Drop and Flow Characteristics
Fluid or gas flowing through a bed of activated carbon encounters resistance, also known as pressure drop, so particle/mesh size also affects how easily water or air moves through a carbon bed. Finer mesh carbon packs tightly, which can slow the flow and increase pressure, while coarser carbon allows fluids or air to move more freely, reducing strain on pumps and equipment. The ideal mesh balances adsorption speed with acceptable pressure drop for the system design.
Contact Time
A key design parameter of adsorption systems is empty bed contact time (EBCT), which is how long fluid is in contact with the carbon bed. For activated carbon to work well, contaminants need enough time to touch the carbon surface.
Finer carbon often requires less contact time for comparable removal of certain contaminants because adsorption can occur quickly at the surface. Larger particles may require a longer contact time but may sustain performance for longer bed life. Selecting a mesh size appropriate for your EBCT target helps optimize treatment efficiency and operating costs.
Handling and System Longevity
Particle size also affects mechanical strength and handling. Smaller particles are more prone to dust formation, abrasion, and attrition during shipment, loading, and operation. Dust can clog filters, damage downstream equipment, and complicate bed uniformity. Larger particles are more robust and easier to manage in large columns or high-flow industrial contexts. A system using high mesh (fine) carbon might need more careful handling and pre-filtration to avoid dust issues.
Types of Activated Carbon and Typical Size Ranges
Activated carbon comes in several forms, and mesh/particle size options vary depending on the application.
Granular Activated Carbon (GAC)
Granular activated carbon is among the most commonly used forms for liquid and air purification. It typically comes in mesh ranges such as:
- 4×8 mesh: Very coarse, used where low pressure drop is critical (e.g., vapor phase adsorption)
- 6×12 mesh: A balance of surface area and flow resistance
- 8×30 mesh: Excellent for liquid phase adsorption with moderate flow rates
- 12×40 mesh: Finer mesh for applications needing higher removal efficiency per volume
- 20×50 mesh: Even finer, often used for more stringent purification requirements
Powdered Activated Carbon (PAC)
Powdered activated carbon is defined by extremely fine particles (e.g., −100 mesh, −200 mesh, etc.) and is commonly used in batch processes or emergency contaminant spikes because it adsorbs rapidly but cannot be easily retained in fixed beds.
Pelletized or Extruded Activated Carbon
Pelletized activated carbon has uniform, cylindrical particles measured by diameter rather than mesh size. Pelletized carbons are ideal in air treatment systems where consistent flow and low dust are priorities.
Choosing the Right Mesh Size for Your Application
Different contaminants interact with activated carbon in different ways. Molecular size, polarity, solubility, and concentration all influence how quickly and effectively a compound is adsorbed. Because of this, mesh size selection should align with the target contaminant as well as system design constraints, such as flow rate and contact time.
Below is a practical comparison of commonly treated contaminants and the mesh sizes typically used for effective removal.
| Contaminant Type | Common Examples | Typical Application | Recommended Mesh / Particle Size | Why This Size Is Used |
| Volatile Organic Compounds (VOCs) | Benzene, toluene, xylene, solvents, fuel vapors | Air and vapor phase treatment | 4×8, 4×10, 6×12, pelletized carbon | Larger particles allow air to flow easily while still capturing VOCs |
| Chlorine & Chloramines | Drinking water disinfectants | Drinking water treatment | 8×30, 12×40 | Smaller particles improve reaction speed and removal efficiency |
| Taste & Odor Compounds | Geosmin, 2-MIB, sulfur compounds | Water polishing, beverage processing | 12×40, 20×50 | Fine mesh allows rapid adsorption of low-concentration compounds that cause strong sensory impacts |
| PFAS & Organic Micropollutants | PFOS and PFOA, pesticides, pharmaceuticals | Municipal and groundwater treatment | 12×40, 20×50, fine GAC or PAC | Increased surface area helps capture difficult, low-level contaminants |
| High Organic Load Streams | Industrial wastewater, landfill leachate | Industrial pretreatment systems | 6×12, 8×30 | Coarser mesh supports higher flow rates, reduces fouling, and extends bed life under heavy loading |
| Batch & Emergency Treatment | Spills, seasonal contamination spikes | Temporary or batch treatments | Powdered activated carbon | Extremely fine particles deliver rapid adsorption but are not suited for fixed beds |
| Odor Control (Gas Phase) | Hydrogen sulfide (H2S), mercaptans | Industrial exhaust and odor systems | 4×8, 4×10, pelletized carbon | Larger particle size minimizes pressure drop and dust in high-volume air streams |
Better Performance Starts With the Right Carbon Size
Mesh size and particle size are fundamental to how activated carbon performs. It influences surface area, adsorption dynamics, flow resistance, contact time, and longevity of the media. Whether choosing an 8×30 mesh for water filtration, a 4×8 mesh for vapor phase cleanup, or powdered carbon for batch treatment, matching mesh size to your system’s needs optimizes performance and cost-efficiency.
With a wide range of granular, powdered, and pelletized activated carbon products available, we at General Carbon can help you match carbon size to your specific needs, ensuring efficient and reliable adsorption. Contact us today to find out which solution is right for your industrial treatment system.