The purification of organic compounds is necessary, though complex, step after its extraction from a natural source or synthesis in the laboratory.
Removal of organic matter by ion exchange was developed in the 1960s as a method of protecting anion exchange resins in a demineralization plant in order to maintain the quality of treated water produced. Ion exchange is an effective method for removing humic substances from drinking water supplies.
In this process, an anionic exchange resin is used to remove negatively charged organic compounds by the exchange of a counter ion, usually chloride, from the resin surface. Natural organic matters are complex organic molecules that contain carboxylic acid active groups, meaning that they will act as weak anions, and will be held on the organic scavenger.
The organic scavenger is a highly porous resin that will allow the organic molecules easy passage in and out of the structure.
Ion exchange resins with a macroporous or macroreticular structure are particularly suited to this application and offer physical strength coupled with capacity and reversibility of organics during regeneration.
Some common natural organic ion exchangers are:
•polysaccharides, such as cellulose and peat
•proteins, such as casein, keratin, and collagen
•carbonaceous materials, such as charcoals, lignites, and coals.
However, only charcoals, coal, lignite, and peat are used in industrial applications.
The ion exchange water softening process can remove nearly all calcium and magnesium from source water. Softeners may also remove as much as 5-10 ppm (parts per million; ppm is equal to milligrams per liter, or mg/L) of iron and manganese.
As ion-exchange treatment will only remove about 70% of the organic matter of the residual organic concentration after scavenger treatment is high enough to cause problems with the final product.
As a general rule waters having an organic content above 1ppm as measured by the 4 hours at 27 degree C permanganate test will require treatment while those waters that have a concentration at 1 ppm or below will not normally require special treatment.
Ion exchange process to remove organic matter from water
