ASTM D6646 Hydrogen Sulfide Breakthrough Capacity of Granular and Pelletized Activated Carbon

Scope:  

Granular and pelletized activated carbons are commonly used to treat odors from sewage, treatment plants, pump stations, and other sources. ASTM D6646 is a standard method used to assess the breakthrough performance of activated carbon for removing hydrogen sulfide from a humidified gas stream. It is important to note that this laboratory test is not intended to simulate actual conditions encountered in an odor control application but to compare the hydrogen sulfide breakthrough capacities of different carbons under controlled laboratory conditions.

It is important to note that this standard only applies to granular and pelletized activated carbons with mean particle diameters less than 2.5 mm. If activated carbons with mean particle diameters greater than 2.5 mm are being evaluated, a larger diameter adsorption column will be required. Additionally, this test does not apply to adsorptive non-carbon materials.

Test Procedure:

The Breakthrough Capacity is determined by exposing a known volume of granular or pelletized activated carbon sample to a humidified air stream containing hydrogen sulfide under specific conditions until the concentration of hydrogen sulfide in the effluent gas reaches 50 ppmv. Afterward, it is feasible to determine the carbon’s H2S adsorption capacity per unit volume at a 99.5% removal efficiency (g H2S/cm3 carbon).

Specimen Size: 

The ASTM D6646 standard method does not prescribe a specific sample size for assessing the hydrogen sulfide breakthrough capacity of granular and pelletized activated carbon. However, the test method guides the preparation of the activated carbon bed and the gas flow rate and composition used during the test. The activated carbon bed is typically contained in a glass or metal column with a 25-40 mm diameter and a length of 75-150 mm. The activated carbon sample is typically 50-100 g, with a 0.25-1.0 mm particle size. The gas flow rate is generally 0.05-0.5 liters per minute.

Data: 

The hydrogen sulfide breakthrough capacity of the test sample is reported. 

Conclusion: 

ASTM D6646 is an essential tool for quality control and research and development in industries that require hydrogen sulfide removal. The standard provides a standardized method for evaluating the effectiveness of activated carbon in removing hydrogen sulfide under controlled laboratory conditions. The test results can be used to compare the performance of different types of activated carbon and optimize the selection of the best-suited material for a particular application.