An anion exchange resin removes organics by exchanging the anionic portion of an organic molecule for an inorganic ion that is exchanged onto the resin. Anion resins are cationic in nature and, therefore, are: attracted to anions. Size, charge and valence affect a particular resin’s affinity for various anions. Low molecular weight organic acids such as acetic acid and formic acid are readily exchanged by anion resins.
These acids are monovalent and do not have high selectivity coffficients. They are readily eluted from the resin during regeneration. The organics that we normally talk about in reference to organic traps are the naturally occurring carboxylic aromatic multivalent types of organics that are loosely grouped as Humic and Tannic materials. These organics are only partially soluble and are not always fully ionized. They have large and bulky structures, have relatively high molecular weight compared to most inorganic ions and often have more than one carboxylic group in each molecule. It is the portion of the organic molecule that is carboxylic that is attracted to the cationic exchange groups of anion exchange resins. The exchange occurs at the surface of the resin bead where chloride or some other inorganic anion is released and an organic carboxylic group exchanges onto the resin. The organic molecule then slowly exchanges in towards the center of the bead. As it does so, additional exchange sites at the surface of the bead become available for further organic removal. Organic acids that contain more than one carboxylic group can exchange for more than one counter ion. As a consequence, due to their divalent or multivalent nature, they can be very selectively held by anion exchange resin.
Lanlang ® TA213 is a premium grade gel type I strong base anion exchange resin with polyacrylic matrix and quaternary amine (Trimethylamine) function group in standard Gaussian size distribution. The acrylic structure offers TA213 with excellent adsorption and desorption of organics. TA213 could be used in multi bed demineralizing system to prevent resins from organic fouling or remove natural organic contaminants from surface water such as Tannin.