For activated carbon used in water treatment projects to remove iron, coconut shell-based or coal-based granular activated carbon (GAC) and catalytic activated carbon blocks are preferred. A small amount of powdered activated carbon can also be used as an auxiliary purification agent. The specifications of different types of activated carbon need to be selected based on factors such as the treatment scenario and the iron content of the water. Specific recommendations are as follows:
1. Granular Activated Carbon (GAC)
This type of activated carbon is the mainstream choice for iron removal in water treatment. It is often filled in filter towers or filters, converting soluble ferrous ions into insoluble iron oxide precipitates through catalytic oxidation and then adsorbing and retaining them. Specific specifications are as follows:
Particle size is mainly 0.6-2mm, but 1-4mm can also be used. 0.6-2mm particle size is suitable for drinking water treatment with low to medium iron content, offering a large specific surface area and low flow resistance; 1-4mm is suitable for industrial wastewater and other scenarios with high turbidity and high iron content, is less prone to clogging, and provides better backwashing effects. An Indian water treatment materials supplier offers activated carbon for iron removal in common sizes such as 0.6-1.2mm and 1-2mm.
For iodine values ≥900mg/g and strength ≥90%, coconut shell-based activated carbon specifically designed for iron removal is preferred due to its strong catalytic activity and efficient oxidation of ferrous ions. Coal-based granular activated carbon offers high cost-effectiveness and is suitable for large-scale industrial water treatment. For example, Henan Linsen's coal-based columnar activated carbon, with a particle size of 1.5-4.0mm, iodine value ≥900mg/g, and strength ≥90%, meets conventional iron removal requirements. Some imported coal-based activated carbons also require an iron content <0.7% to avoid water pollution.
Shape: Columnar or irregularly shaped broken carbon. Columnar carbon (commonly Φ1.5mm, Φ3.0mm, Φ4.0mm, etc.) has a regular structure, uniform pores during filling, and stable water flow distribution. Irregularly shaped broken carbon fits snugly into the filter layer gaps, resulting in better adsorption, retention, and sedimentation effects.
2. Catalytic activated carbon blocks are suitable for small commercial or household water purification equipment. They enhance iron removal through a special media formulation and are often manufactured as filter cartridges. The core specification is a pore size of 0.2 microns, which directly traps oxidized iron precipitates while removing residual chlorine, VOCs, and other impurities. Common sizes include standard cartridges such as 2.5" × 10" cartridges, compatible with conventional water purification equipment. They must meet NSF and other certification standards to ensure material safety. Through catalytic oxidation technology, they can simultaneously remove iron, manganese, and other metal ions, making them suitable for point-of-use water purification scenarios.
3. Powdered activated carbon (PAC) is generally not used as the primary iron removal medium alone. It is mostly used in emergency treatment or as an auxiliary purification method, such as when raw water is suddenly contaminated with high iron levels. It can be added in conjunction with other iron removal processes. A fine particle size of 100 mesh or higher is recommended, as this allows for rapid dispersion in water and adsorption of tiny iron oxide particles. Simultaneously, impurities must be controlled, such as a total iron content ≤0.10% to avoid secondary pollution, and ignition residue ≤5% to ensure adsorption purity.
Additional Precautions: Activated carbon for iron removal often needs to be used in conjunction with oxidation processes (such as aeration, addition of chlorine oxidants, etc.) to enhance the iron removal effect. In this case, the activated carbon mainly acts as a catalyst and adsorption carrier. Additionally, if the raw water pH is low, it needs to be adjusted to above 7 first to ensure the catalytic oxidation efficiency of the activated carbon. Regular backwashing is also necessary during use to prevent iron deposits from clogging the pores and extending the service life of the activated carbon.
