Lewatit® FO 36 is a macroporous, monodispersed, polystyrene-based resin for the selective adsorption of oxoanions, such as arsenate or arsenite ions. It is a weakly basic ion exchange resin which is dropped with a nano-scaled film of iron oxide covering the inner surfaces of the pores of the polymer bead. Oxoanions are bond by a specific, reversible reaction involving hydroxyl-groups on the iron oxide surface. Other anions such as SO4, NO3, Cl, HCO3; have a neglectable influence on arsenic adsorption. Optimum pH is pH=6. Lewatit FO 36 is especially suitable for use in the following applications:- Removal of arsenic from drinking water
- Removal of arsenic from ground water (ground water remediation) and waste water
- Removal of arsenic from process solutions even in presence of high contents of neutral salts (e.g. >10% NaCl on Na2SO4)
In the purification of potable water arsenic can be removed down to rest concentrations significantly lower than 10 microgram/l which is the maximum containment level set in several countries. Besides of arsenic containing oxyanions such as arsenate and aresenite Lewatit FO 36 is capable of selectively adsorbing other species as there are HPO4, HSiO3, HSbO4, SCN, etc. Also it has to be considered that the weakly basic anion exchange group in the resin is still active and can react int eh specific way basically known for this kind of functional group. Hence Lewatit FO 36 can also bind natural organic matter such as tannins, lignins, negatively charged uranium complexes, chromate and others. Lewatit FO 36 should never be exposed to solutions with pH lower than 4. Otherwise iron oxide will be dissolved and washed out and the resin will lose its dedicated functionality. Advantages of polymer resin based iron oxide doped adsorbers compared to a basically inorganic adsorber are:- Regenerability
- No bleeding of fine iron oxide particles
- High mechanical strength and therefore easy to backwash or to pump in suspension
- No blocking of the resin bed due to build up of fines
- Fast kinetics due to large surface area and optimized pore structure.
When using Lewatit FO 36 to treat potable water special care should be giving tot eh start up of the new resin.Information provided by Lanxess. |
