Activated Carbon Basics
If you are new to the industry, or just have questions about a specific area, you should find this primer helpful. For additional resources, follow the links in the right hand column.
Adsorptive Tests
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Don't be fooled by standard surrogate adsorptive tests. Some people base their choice of activated carbon on a particular adsorptive specification such as iodine number. This only makes sense when the size and shape of the contaminants to be removed are similar to the substances used in lab testing. This may not be a reliable way to predict effectiveness of activated carbons if multiple contaminants are present, the contaminants are unknown, or the molecular structure and size of the contaminant molecules are different than the surrogate used in a lab adsorption test.
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The iodine number test can usually predict effectiveness when very small molecules are to be adsorbed. Tannin value and molasses number or molasses decolorizing efficiency are more appropriate in lab test parameters for medium and large-sized molecules or when small molecules are present with larger molecules. For example, to solve taste, odor and other impurity problems in drinking water, the best type of activated carbon is not so easily determined because of the variety of molecules that cause the problems.
These impurity molecules can range from very small to very large in size. The large molecules often clog up small pores, making them inaccessible to other molecules. A better match for this application is often an activated carbon with more medium-sized pores. Norit recommends performance testing first to identify the best activated carbon for a specific application.
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