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Bifunctional Anion Exchange Resin DevelopmentOak Ridge, TNSource: Gu, Baohua, and G.M. Brown, 2000, "Efficient Removal of Perchlorate (ClO4-) From Contaminated Water by Highly Selective, Regenerable Bifunctional Resins" in Perchlorate Treatment Technology Workshop, 5th Annual Joint Services Pollution Prevention & Hazardous Waste Management Conference & Exhibition, August 21-24, 2000, Henry B. Gonzalez Convention Center, San Antonio, Texas. Project Summary: The following text was excerpted from Gu, Baohua, and G.M. Brown, 2000, "Efficient Removal of Perchlorate (ClO4-) From Contaminated Water by Highly Selective, Regenerable Bifunctional Resins" in Perchlorate Treatment Technology Workshop, 5th Annual Joint Services Pollution Prevention & Hazardous Waste Management Conference & Exhibition, August 21-24, 2000, Henry B. Gonzalez Convention Center, San Antonio, Texas: The Oak Ridge National Laboratory (ORNL) and University of Tennessee have recently developed a new class of bifunctional anion exchange resins (U.S. patent # 6,059,975), which are highly selective for sorption of ClO4- from contaminated groundwater or surface water. The bifunctional anion exchange resins were initially developed under DOE sponsorship for pertechnetate (TcO4-) removal at ppt levels. Perchlorate behaves similarly to pertechnetate, as both are large, poorly hydrated anions. The bifunctional resins consist of quaternary ammonium groups with both large (C6) and small (C2) alkyl groups resulting in high selectivity and good exchange kinetics. Laboratory studies utilized a flow rate of 17 bed volumes per minute, and influent perchlorate concentrations of 1,000 or 10,000 ppb. The chemistry of the synthetic water used in the laboratory studies was as follows: 106 mg/L chlorine, 0 mg/L fluorine, 31 mg/L nitrate, 49 mg/L sulfate, 183 mg/L bicarbonate, 1,000-10,000 ug/L perchlorate, and pH 8.3. The bifuntional resin tested was RO-02-119, with trihexylamine/triethylamine functional groups synthesized at the University of Tennessee, Knoxville. Commercial monofunctional resins tested included Purolite A-520E, with triethylamine functional groups by Purolite International, and Sybron SR- 6, with tributylamine functional groups by Sybron Chemicals, Inc. Test results indicate that the bifunctional resins are highly selective toward ClO4- and perform about five times better than one of the best commercial nitrate-selective resins (Purolite® A-520E). Additionally, a new regeneration technology (U.S. patent pending, 09/491,242) has been developed at ORNL so that these anion-exchange resins can be used repeatedly over a long-term operation. The regeneration process uses tetrachloroferrate (FeCl4-), is cost-effective and generates minimal amounts of secondary wastes. No decrease in resin performance after seven cycles of perchlorate loading and regeneration were noted, on tests with the D-3696 resin column (10 x 22 mm), with 17 BV/minute flow, and 10 mg/L initial perchlorate concentration. Therefore, the new resin and new regeneration technology offer a promising solution to remediate the ClO4-- contaminated groundwater or surface water by using either the conventional pump-and-treat or the funnel-and-gate treatment configurations (with regenerable treatment systems). Additional Info Source: Gu, Baohua, and G.M. Brown, 2000, "Efficient Removal of Perchlorate (ClO4-) From Contaminated Water by Highly Selective, Regenerable Bifunctional Resins" in Perchlorate Treatment Technology Workshop, 5th Annual Joint Services Pollution Prevention & Hazardous Waste Management Conference & Exhibition, August 21-24, 2000, Henry B. Gonzalez Convention Center, San Antonio, Texas. |
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