Anion exchange molecular properties

Researchers found that zeolite particles can be treated with high-molecular-weight surfactants [such as hexadecyltrimethylammonium (HDTMA)]. HDTMA does not penetrate into the internal pore structure of the zeolite, but coats the outer surface. The outer surface then develops hydrophobic anionic exchange properties, while the inner surface retains the capacity to adsorb cations. Researchers claim that SMZ can be used for the three major classes of water contaminants inorganic cations, inorganic anions, and nonpolar organics. 

Similar relationships between the properties of the phenylureas and their adsorption by a weakly basic anion exchange resin were found (Table X). The relationships between the properties of the phenylureas and their adsorption by the two adsorbents will be published elsewhere. In summary, it appears that the phenylureas exhibit weakly acidic properties and are partially adsorbed to particulate matter as anionic species but probably primarily as molecular species. Adsorption is probably primarily through dipole—ion or dipole—dipole bonding mechanisms. Larger molecules are generally adsorbed more than smaller molecules. Compounds of lower water solubility are adsorbed more than those of higher water solubility. Dimethylureas seem to be adsorbed by a slightly different mechanism than methoxy methyl compounds. 

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