What do squirrels have to do with removing pesticides from wastewater? You may well ask! I’ve been thinking about competitive adsorption for cypermethrin removal and find a useful analogy in red squirrel conservation. Red squirrels are smaller than grey squirrels. That difference in size can be exploited when designing feeders: by setting the mechanism around a carefully chosen weight, food can be made accessible to the smaller red squirrel while restricting access by the heavier grey squirrel. And that is rather like what happens inside a granular activated carbon filter (GAC) filter. GAC has a distribution of pore sizes. The measures of its absorption quality are iodine number and methylene blue number. The iodine number indicates the carbon's capacity for adsorbing small molecules, i.e the amount of microporosity. Methylene blue is a considerably larger molecule, so quantifies the adsorption capacity associated with larger meso-pores. So they act rather like red and grey...
Posts
Squirrels and methylene blue
What do squirrels have to do with removing pesticides from wastewater? You may well ask! I’ve been thinking about competitive adsorption for cypermethrin removal and find that a useful analogy comes from an unlikely place: red squirrel conservation . Red squirrels are smaller than grey squirrels. That difference in size can be exploited when designing feeders: by setting the mechanism around a carefully chosen weight, food can be made accessible to the smaller red squirrel while restricting access by the heavier grey squirrel. It is, essentially, selective access . And that is rather like what happens inside an activated carbon filter. Granular activated carbon (GAC) isn't just a giant sponge with an infinite number of identical holes. It has a distribution of pore sizes. The traditional iodine number gives us an indication of the carbon's capacity for adsorbing small molecules and is strongly associated with its microporosity. Methylene ...
GAC cypermethrin
In Granular Activated Carbon (GAC) testing, iodine and methylene blue serve as surrogate indicators representing different classes of target molecules based on molecular size and pore accessibility . [ 1 , 2 ] Iodine Represents Small Molecules Molecular Trait: Iodine (I₂) is a very small molecule with a molecular diameter of roughly 0.56 nm . [ 1 ] Target Pore Range: It represents contaminants that fit into the micropores (pores smaller than 2 nm) of the carbon. [ 1 , 2 , 3 ] Represented Molecules: The Iodine Number indicates the GAC's capacity to remove low-molecular-weight organic compounds and raw disinfection byproduct precursors. Examples of molecules represented by iodine include: Volatile Organic Compounds (VOCs) Trihalomethanes (THMs) Taste and odor compounds (such as geosmin and 2-methylisoborneol) Chlorinated solvents Chlorine and iodine-like micropoll...