How do GAC and PAC differ? How to choose the appropriate activated carbon for each treatment system

Coconut shell activated carbon can be used in various forms, among which GAC (Granular Activated Carbon) and PAC (Powdered Activated Carbon) are two common forms. Each form has different characteristics and methods of use, so the selection should be based on the substance to be treated, operating conditions, and the design of each system.

What are GAC and PAC?

GAC - Granular Activated Carbon is granular activated carbon. With a relatively large size, GAC is often arranged as a fixed bed of material in filter columns, filter tanks, or continuous treatment systems. Water or gas passes through the carbon bed, and the components to be treated are retained on the surface and within the pore system of the material.

For coconut shell activated carbon, some common GAC sizes include 4×8, 6×12, 8×20, 8×30, and 12×40 mesh. Thanks to its granular form and good mechanical strength, GAC is suitable for systems that need to operate for a long time and minimize material breakage or entrainment in the treatment stream.

GAC is used in many applications such as water and wastewater treatment, industrial water filter columns, air filtration and deodorization, solvent vapor adsorption, oil filtration, oil and gas, thermal power, and some food, chemical, and pharmaceutical processes.

PAC - Powdered Activated Carbon is fine powdered activated carbon. For coconut shell activated carbon, PAC sizes can typically range from 200 - 325 mesh.

Unlike GAC, which is retained in filter columns, PAC is usually introduced directly into the water or solution to be treated. Thanks to its small size, PAC can disperse quickly and create a large contact area with the treatment medium.

After the adsorption process, PAC usually needs to be removed from the system by stages such as sedimentation, filtration, or other suitable separation methods.

PAC is often used in water and wastewater treatment, decolorization, deodorization, textile dyeing wastewater treatment, some food, chemical, oil and gas, and oil refining processes.

How do GAC and PAC differ?

Overall, GAC is suitable for systems using a fixed carbon bed and requiring continuous operation, while PAC is suitable for processes that require direct addition of carbon to the treatment medium.

Should you choose GAC or PAC?

The choice between GAC and PAC should not only be based on adsorption capacity but also consider the substance to be treated, the treatment environment, system design, and operating method.

If the system uses filter columns, filter tanks, or a fixed bed of material and requires continuous operation, GAC is often the suitable form to consider. The granular form has good mechanical strength, which is advantageous for retaining the material within the system and for replacement after use.

Conversely, if carbon needs to be introduced directly into water or a solution for treatment, PAC may be more suitable. Its small size allows PAC to disperse quickly in the medium, and the amount of carbon can be flexibly adjusted according to treatment conditions. However, a suitable method is required to separate the spent carbon from the system after the adsorption process. In addition to choosing between GAC or PAC, businesses also need to consider the following factors:

• Treatment medium: water, wastewater, gas, or solution.
• Substance to be removed: composition and characteristics of the substance to be adsorbed.
• Inlet concentration and outlet requirements: determine the necessary treatment level.
• Flow rate and contact time: affect actual adsorption conditions.
• Equipment used: filter columns, filter tanks, or direct dosing systems.
• Particle size: needs to be compatible with the equipment and operating method.
• Technical specifications: Iodine, CTC, surface area, pore structure, hardness, ash content, and moisture content.

In particular, activated carbon should not be chosen based solely on a single parameter such as Iodine (the amount of iodine that a unit mass of activated carbon can adsorb). A product with a higher Iodine value may not necessarily be more suitable if its particle size, hardness, pore structure, or other characteristics do not meet the actual conditions of the system. Therefore, it is advisable to start from the actual treatment requirements and then compare them with the technical specifications of each grade.

Coconut Shell Activated Carbon GAC and PAC from MEISEI INTERNATIONAL TRADING

MEISEI INTERNATIONAL TRADING supplies coconut shell activated carbon in granular GAC and powdered PAC forms, serving various needs for water treatment, air treatment, deodorization, and industrial applications.

• GAC: Iodine value approximately 500–1,400 mg/g, various particle sizes such as 4×8, 6×12, 8×20, 8×30, and 12×40 mesh.
• PAC: Iodine value approximately 500–1,200 mg/g, size 200–325 mesh.

With a wide range of product forms, Iodine values, and particle sizes, MEISEI INTERNATIONAL TRADING can meet various requirements depending on the intended use and conditions of each system.

■ Please download the PDF document for more details or contact MEISEI INTERNATIONAL TRADING for consultation.