Activated carbon is one of the most widely used adsorbents in various industries. Due to its porous structure and large surface area, it has a high adsorption capacity for organic and inorganic substances. It is widely used in water treatment, industrial air purification, the food and pharmaceutical industries, and chemical processes. Mechanical strength is one of the most important properties of activated carbon and directly influences its performance characteristics and service life.
Several standards have been developed to measure this property, and ASTM D2862 is particularly known as the reference method for determining the mechanical strength of activated carbon.
The importance of the mechanical strength of activated carbon
Activated carbon is subjected to significant mechanical stress during transport, loading into adsorption columns, and constant contact with liquids. If the carbon particles are not sufficiently stable, they will disintegrate into smaller particles over time. In addition to reducing their adsorption capacity, this phenomenon can also cause the following problems:
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Pressure drop in the absorption tower,
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Clogged filters and piping systems,
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Increased operating and maintenance costs,
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Reduced service life of the absorbent layer
Therefore, it is important to determine the mechanical hardness and select activated carbon with sufficient strength for the intended application.
Introduction to ASTM D2862
ASTM D2862 or “Standard Test Method for Particle Size Distribution of Granular Activated Carbon for Mechanical Hardness ” is one of the most important international standards in the field of mechanical hardness testing.
This standard, developed by the American Society for Testing and Materials (ASTM International), establishes a specific method for measuring the mechanical strength of activated carbon granules. It is intended to provide a quantitative and reproducible standard that facilitates the comparison of different activated carbon types.
Principle of the test method
The basic idea of ASTM D2862 is that activated carbon particles are subjected to impact and abrasion under controlled conditions and the degree of fragmentation is then measured.
The main phases are as follows:
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Sampling : Select a specific amount of granular activated carbon (with a specific particle size).
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Application of mechanical loading : The sample is placed in a hardness tester. This tester is a rotating cylinder that subjects the carbon to shock and abrasion loads.
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Sieve analysis : After a specified period of time, the sample is removed from the device and sieved through a series of sieves.
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Calculation of mechanical strength : The percentage of particle weight that remains unchanged (i.e. unbroken) after the test is given as the index of mechanical strength.
Factors influencing mechanical hardness
There are several important factors that can affect ASTM D2862 test results:
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Raw material type : Activated carbon can be made from coal, wood, or coconut shells. Activated carbon from coconut shells is harder than activated carbon from wood.
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Activation method : The final strength is influenced by physical or chemical activation.
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Manufacturing process conditions : Temperature, pressure and activation time are crucial factors.
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Particle size and shape : Spherical particles are generally harder than angular ones.
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Moisture content : Wet samples may show different results than dry samples.
Practical application of the test results
The test results of ASTM D2862 are widely used in many industries, including:
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Selection of activated carbon for adsorption tower : In petrochemical or oil refining industry, it is very important to select carbon with high hardness to avoid destruction.
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Manufacturer Quality Control : Manufacturing companies use this test to control the quality of their products and ensure that they meet standards.
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Comparison between different suppliers : Buyers can compare activated carbon from different manufacturers based on their mechanical hardness.
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Improved design process : Test results can help absorption system designers select columns and filters based on the mechanical properties of the carbon.
Advantages of using ASTM D2862
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High reproducibility : Standardized methods make results comparable between different laboratories.
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Easy implementation : The required equipment is relatively simple.
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Guaranteed industrial performance : Results are directly related to actual performance under operating conditions.
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Reduced costs : Choosing the right coal can reduce replacement and maintenance costs.
Test limits
Although ASTM D2862 is a recognized method, it has limitations:
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It is intended only to ensure mechanical strength under laboratory conditions and may not reflect all real-life operating conditions.
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Not suitable for some types of activated carbon, such as powdered activated carbon (PAC).
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Test results are influenced by device configuration and operator skills.
Compared to other standards
In addition to ASTM D2862, there are other standards for determining the mechanical strength of activated carbon, such as:
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ASTM D3802 : Corrosion resistance test for activated carbon.
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DIN 53583 : German standard for measuring mechanical hardness.
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JIS K1474 : Japanese standard for activated carbon.
However, due to its simplicity and broad applicability, the ASTM D2862 standard is more commonly used worldwide.
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Finally
Mechanical strength is one of the most important properties of activated carbon and determines its durability, service life, and effectiveness in industrial environments. ASTM D2862 , one of the most authoritative test methods, establishes specific criteria for evaluating and comparing activated carbon.
Conducting these tests helps the industry ensure the selection of appropriate sorbents, reduce problems associated with particle breakage, and improve the efficiency of the absorption process. Focusing on this property and implementing recognized standards such as ASTM D2862 will ultimately significantly improve quality and reduce operating costs.