title: Aqueous (99)Tc, (129)I and (137)Cs removal from contaminated groundwater and sediments using highly effective low-cost sorbents.
abstract: Technetium-99 ((99)Tc), iodine-129 ((129)I), and cesium-137 ((137)Cs) are among the key risk-drivers for environmental cleanup. Immobilizing these radionuclides, especially TcO4(-) and I(-), has been challenging. TcO4(-) and I(-) bind very weakly to most sediments, such that distribution coefficients (Kd values; radionuclide concentration ratio of solids to liquids) are typically <2 mL/g; while Cs sorbs somewhat more strongly (Kd ∼ 50 mL/g). The objective of this laboratory study was to evaluate 13 cost-effective sorbents for TcO4(-), I(-), and Cs(+) uptake from contaminated groundwater and sediments. Two organoclays sorbed large amounts of TcO4(-) (Kd > 1 × 10(5) mL/g), I(-) (Kd ≥ 1 × 10(4) mL/g), and Cs(+) (Kd > 1 × 10(3) mL/g) and also demonstrated a largely irreversible binding of the radionuclides. Activated carbon GAC 830 was effective at sorbing TcO4(-) (Kd > 1 × 10(5) mL/g) and I(-) (Kd = 6.9 × 10(3) mL/g), while a surfactant modified chabazite was effective at sorbing TcO4(-) (Kd > 2.5 × 10(4) mL/g) and Cs(+) (Kd > 6.5 × 10(3) mL/g). Several sorbents were effective for only one radionuclide, e.g., modified zeolite Y had TcO4(-)Kd > 2.3 × 10(5) mL/g, AgS had I(-) Kd = 2.5 × 10(4) mL/g, and illite, chabazite, surfactant modified clinoptilolite, and thiol-SAMMS had Cs(+)Kd > 10(3) mL/g. These low-cost and high capacity sorbents may provide a sustainable solution for environmental remediation.
authors.affiliation: Savannah River National Laboratory, Aiken, SC 29808, United States. Electronic address: Dien.Li@srs.gov.
authors.forename: Dien
authors.initials: D
authors.lastname: Li
authors.affiliation: Savannah River National Laboratory, Aiken, SC 29808, United States.
authors.forename: Daniel I
authors.initials: DI
authors.lastname: Kaplan
authors.affiliation: Savannah River National Laboratory, Aiken, SC 29808, United States.
authors.forename: Anna S
authors.initials: AS
authors.lastname: Knox
authors.affiliation: Savannah River National Laboratory, Aiken, SC 29808, United States.
authors.forename: Kimberly P
authors.initials: KP
authors.lastname: Crapse
authors.affiliation: Savannah River National Laboratory, Aiken, SC 29808, United States.
authors.forename: David P
authors.initials: DP
authors.lastname: Diprete
mesh_terms: D000327:Adsorption; D002588:Cesium Radioisotopes / Q000737:chemistry; D003666:Decontamination / Q000379:methods*; D019015:Geologic Sediments / Q000032:analysis*; D060587:Groundwater / Q000032:analysis*; D007457:Iodine Radioisotopes / Q000737:chemistry; D013667:Technetium / Q000737:chemistry; D014875:Water Pollutants, Radioactive / Q000737:chemistry*; D014878:Water Pollution, Radioactive / Q000517:prevention & control*
chemical_list: D002588:Cesium Radioisotopes; D007457:Iodine Radioisotopes; D014875:Water Pollutants, Radioactive; D013667:Technetium
keywords: Cesium; Iodine; Organoclays; Sorbents; Technetium