title: Regeneration of perchlorate (ClO4-)-loaded anion exchange resins by a novel tetrachloroferrate (FeCl4-) displacement technique.
abstract: Selective ion exchange is one of the preferred treatment technologies for removing low levels of perchlorate (ClO4-) from contaminated water because of its high efficiency and minimal impact on water quality through the addition or removal of chemicals and nutrients. However, the exceptionally high affinity of ClO4- for type I anion-exchange resins makes regeneration with conventional NaCl brine extremely difficult and costly for practical applications. The present study entails the development of a novel regeneration methodology applicable to highly selective anion-exchange resins. Tetrachloroferrate (FeCl4-) anions, formed in a solution of ferric chloride and hydrochloric acid (e.g., 1 M FeCl3 and 4 M HCl), were found to effectively displace Cl04- anions that were sorbed on the resin. A mass-balance analysis indicated that a nearly 100% recovery of ion-exchange sites was achieved by washing with as little as approximately 5 bed volumes of the regenerant solution in a column flow-through experiment There was no significant deterioration of the resin's performance with respect to ClO4- removal after repeated loading and regeneration cycles. Thus, the new methodology may offer a cost-effective means to regenerate ClO4- -loaded resins with improved regeneration efficiency, recovery, and waste minimization in comparison with conventional brine regeneration techniques.
authors.affiliation: Environmental Sciences Division, Oak Ridge National Laboratory, Tennessee 37831, USA. gubl@ornl.gov
authors.forename: B
authors.initials: B
authors.lastname: Gu
authors.forename: G M
authors.initials: GM
authors.lastname: Brown
authors.forename: L
authors.initials: L
authors.lastname: Maya
authors.forename: M J
authors.initials: MJ
authors.lastname: Lance
authors.forename: B A
authors.initials: BA
authors.lastname: Moyer
mesh_terms: D000837:Anion Exchange Resins / Q000737:chemistry*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D017606:Chlorine Compounds / Q000737:chemistry; D005290:Ferric Compounds / Q000737:chemistry; D010472:Perchlorates / Q000737:chemistry*; D017670:Sodium Compounds / Q000737:chemistry*; D014874:Water Pollutants, Chemical; D014876:Water Pollution / Q000517:prevention & control*
chemical_list: D000837:Anion Exchange Resins; D017606:Chlorine Compounds; D005290:Ferric Compounds; D010472:Perchlorates; D017670:Sodium Compounds; D014874:Water Pollutants, Chemical; C031068:sodium perchlorate