The Treatability of Perchlorate in Groundwater Using Ion-Exchange Technology

Tc-99 Ion Exchange Resin Testing

“…Ion-exchange technology has been widely used for various separation processes, such as industrial processing of semi-conductors, water softening, and wastewater and groundwater treatment (Batista et al 2000, Tripp and Clifford 2000, Helfferich 1995, Melis et al 1996, Marina et al 1996, Tao and Xiao 1996, Sorg et al 1999, and Guseva et al 1988. The ion-exchange mechanism is generally known as being the result of simple electrostatic interaction, although factors such as the size and nature of counter-ions, their hydration energy, and the types of functional groups on resin surfaces significantly impact the thermodynamics and kinetics of the exchange reactions (Moyer and Bonnesen 1997, Gu et al 2000b.…”

Combining Ion‐exchange (IX) technology and biological reduction for perchlorate removal

“…Several technologies, including chemical reduction, carbon adsorption, membrane filtration (Yoon et al, 2000), biological reduction (Miller & Logan, 2000;Rittmann & Nerenberg, 2000;Liu & Batista, 2000), and ion exchange (Tripp & Clifford, 2000a;Batista et al, 2000;Gu et al, 2000a) have been investigated.Thus far, biological reduction and ion exchange seem to be the most promising.While the water industry is familiar with the use of ion exchange because of its historic use for hardness and nitrate removal, the industry is not very comfortable with the intentional introduction of microorganisms to the water treatment train.Thus it is likely that biological reduction of perchlorate will not be used for perchlorate removal from drinking waters. Ion Combining Ion-Exchange (IX) Technology and Biological Reduction for Perchlorate Removal exchange will be probably the technology of choice to remove perchlorate from several contaminated drinking waters.…”

“…The degree of cross-linking and resin porosity was found to be of minor significance in determining the affinity between perchlorate and IX resins (Tripp & Clifford, 2000a). Gregor et al (1954) also demonstrated that changing the percent cross-linking from 3 percent to 16 percent has only a minor effect on the separation factors of quaternary ammonium anion-exchange resins toward perchlorate.…”

“…Perchlorate is a large (58.8 cm 3 /g-mole) single-charged anion with a hydration number of four (Schilt, 1979).These physical characteristics have led to the classification of perchlorate as a poorly hydrated, hydrophobic anion (Guter, 2000;Gu et al, 2000b). Thus higher affinity should exist between IX resins with hydrophobic matrices (e.g., styrenic type resin) and perchlorate.The work of Clifford (2000b and demonstrates that the two most significant factors controlling the affinity between perchlorate and IX resins are the type of resin matrix and the type of functional group attached to the resin. Higher separation factors were found for polystyrenic (more hydrophobic) as compared to polyvinylpyridine and polyacrylic type resins, respectively.The results of fixed-bed column testing by Batista et al (2000) agree with the observations of Tripp and Clifford.…”

Treatment of Perchlorate-Contaminated Groundwater Using Highly-Selective, Regenerable Anion-Exchange Resins at Edwards Air Force Base

“…These resins are called "bifunctional" anionexchange resins because they have two quaternary ammonium groups: the first has long alkyl chains for higher selectivity, and the second has shorter alkyl chains for improved reaction kinetics. Treatment by ion exchange using these highly-selective anion exchange resins is one of the most promising methods for removing ClO 4 -at low concentration levels (Gu et al, 2000a,b;Brown et al, 2000;Bonnesen et al, 2000;Venkatesh et al, 2000;Tripp and Clifford, 2000;Batista et al, 2000). In addition to successful benchscale demonstrations, a recent field experiment showed that one bifunctional resin bed (Purolite D-3696) was able to treat more than 100,000 bed volumes of groundwater before a significant breakthrough of ClO 4 -occurred (with an initial ClO 4 -concentration of ~50 µg/L) (Gu et al, 2000a).…”