Performance of three resin-based materials for treating uranium-contaminated groundwater within a PRB.
Three materials that are designed to treat uranium-contaminated water were investigated. These are a cation exchange resin, IRN 77; an anion exchange resin, Varion AP; and a recently developed material called PANSIL (quartz sand coated with 2% amidoxime resin by weight). The reaction rate, capacity, and effective pH range of the three materials are reported. The capacity and conditional distribution coefficient in neutral, uranyl-contaminated synthetic groundwater containing carbonate are also reported. The suitability of each material for treating uranium-contaminated groundwater using a permeable reactive barrier (PRB) approach is then discussed. All three materials react rapidly in the pH range 5-7, reaching equilibrium in less than 4h at approximately 23 degrees C. The unconditioned cation exchange resin removed 8 g UO2 2+ per kg of resin from neutral synthetic groundwater containing 30 mg/l of UO2 2+, but a lower capacity is anticipated in groundwater with either higher ionic strength or lower UO2 2 concentrations. It operates by first acidifying the solution, then sorbing UO2 2, and can release UO2 2 when its buffering capacity has been exhausted. The anion exchange resin is very effective at removing anionic uranyl carbonate species from solutions with a pH above 5, with good specificity. Up to 50 g/kg of uranium is removed from contaminated groundwater at neutral pH. PANSIL is effective at sequestering cationic and neutral uranyl species from solutions in the pH range 4.5-7.5, with very good specificity. The capacity of PANSIL is pH-dependent, increasing from about 0.4 g/kg at pH 4.5, to about 1 g/kg at pH 6, and 1.5 g/kg around pH 7.5. In neutral groundwater containing carbonate, both the anion exchange resin and PANSIL exhibit conditional distribution coefficients exceeding 1470 ml/g, which is about an order of magnitude higher than comparable reactive barrier materials reported in the literature.
Barton
Catherine S
CS
School of Civil Engineering, University of Leeds, Leeds LS2 9JT, UK.
Stewart
Douglas I
DI
Morris
Katherine
K
Bryant
David E
DE
D000327:Adsorption; D000837:Anion Exchange Resins / Q000737:chemistry; D002411:Cation Exchange Resins / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007475:Ion Exchange Resins / Q000737:chemistry*; D011791:Quartz; D012117:Resins, Synthetic / Q000737:chemistry; D014501:Uranium / Q000737:chemistry* / Q000302:isolation & purification; D018505:Waste Management / Q000379:methods; D014867:Water / Q000737:chemistry*; D014875:Water Pollutants, Radioactive / Q000302:isolation & purification
D000837:Anion Exchange Resins; D002411:Cation Exchange Resins; D007475:Ion Exchange Resins; D012117:Resins, Synthetic; D014875:Water Pollutants, Radioactive; D014867:Water; D011791:Quartz; D014501:Uranium; C046797:amberlite