Competitive TcO4-, IO3-, and CrO42- Incorporation into Ettringite.

Ettringite is a naturally occurring mineral found in cementitious matrices that is known for its ability to incorporate environmentally mobile oxyanion contaminants. To better assess this immobilization mechanism for contaminants within cementitious waste forms intended for nuclear waste storage, this work explores how mixed oxyanion contaminants compete for ettringite incorporation and influence the evolving mineralogy. Ettringite was precipitated in the presence of TcO4-, IO3-, and/or CrO42-, known contaminants of concern to nuclear waste treatment, over pre-determined precipitation periods. Solution analyses quantified contaminant removal, and the collected solid was characterized using bulk and microprobe X-ray diffraction coupled with pair distribution function and microprobe X-ray fluorescence analyses. Results suggest that ≥96% IO3- is removed from solution, regardless of ettringite precipitation time or the presence of TcO4- or CrO42-. However, TcO4- removal remained <20%, was not significantly improved with longer ettringite precipitation times, and decreased to zero in the presence of IO3-. When IO3- is co-mingled with CrO42-, calcite and gypsum are formed as secondary mineral phases, which allows for oxyanion partitioning, e.g., IO3- incorporation into ettringite, and CrO42- incorporation into calcite. Results from this work exemplify the importance of competitive immobilization when assessing waste form performance and environmental risk of contaminant release.

Immobilizing Pertechnetate in Ettringite via Sulfate Substitution.

Technetium-99 immobilization in low-temperature nuclear waste forms often relies on additives that reduce environmentally mobile pertechnetate (TcO4-) to insoluble Tc(IV) species. However, this is a short-lived solution unless reducing conditions are maintained over the hazardous life cycle of radioactive wastes (some ∼10,000 years). Considering recent experimental observations, this work explores how rapid formation of ettringite [Ca6Al2(SO4)3(OH)12·26(H2O)], a common mineral formed in cementitious waste forms, may be used to directly immobilize TcO4-. Results from ab initio molecular dynamics (AIMD) simulations and solid-phase characterization techniques, including synchrotron X-ray absorption, fluorescence, and diffraction methods, support successful incorporation of TcO4- into the ettringite crystal structure via sulfate substitution when synthesized by aqueous precipitation methods. One sulfate and one water are replaced with one TcO4- and one OH- during substitution, where Ca2+-coordinated water near the substitution site is deprotonated to form OH- for charge compensation upon TcO4- substitution. Furthermore, AIMD calculations support favorable TcO4- substitution at the SO42- site in ettringite rather than gypsum (CaSO4·2H2O, formed as a secondary mineral phase) by at least 0.76 eV at 298 K. These results are the first of their kind to suggest that ettringite may contribute to TcO4- immobilization and the overall lifetime performance of cementitious waste forms.

Association of Defects and Zinc in Hematite.

Zn is an essential micronutrient that is often limited in tropical, lateritic soils in part because it is sequestered in nominally refractory iron oxide phases. Stable phases such as goethite and hematite, however, can undergo reductive recrystallization without a phase change under circumneutral pH conditions and release metal impurities such as Zn into aqueous solutions. Further, the process appears to be driven by Fe vacancies. In this contribution, we used ab initio molecular dynamics informed extended X-ray absorption fine structure spectra to show that Zn incorporated in the structure of hematite is associated with coupled O-Fe and protonated Fe vacancies, providing a potential link between crystal chemistry and the bioavailability of Zn.

Incorporation Modes of Iodate in Calcite.

Iodate (IO3-) incorporation in calcite (CaCO3) is a potential sequestration pathway for environmental remediation of radioiodine-contaminated sites (e.g., Hanford Site, WA), but the incorporation mechanisms have not been fully elucidated. Ab initio molecular dynamics (AIMD) simulations and extended X-ray absorption fine structure spectroscopy (EXAFS) were combined to determine the local coordination environment of iodate in calcite, the associated charge compensation schemes (CCS), and any tendency for surface segregation. IO3- substituted for CO32- and charge compensation was achieved by substitution of Ca2+ by Na+ or H+. CCS that minimized the I-Na/H distance or placed IO3- at the surface were predicted by density functional theory to be energetically favored, with the exception of HIO3, which was found to be metastable relative to the formation of HCO3-. Iodine K-edge EXAFS spectra were calculated from AIMD trajectories and used to fit the experimental spectrum. The best-fit combination consisted of a significant proportion of surface-segregated IO3- and charge compensation was predominantly by H+. Important implications are therefore that pH should strongly affect the extent of IO3- incorporation and that IO3- accumulated at the surface of CaCO3 particles may undergo mobilization under conditions that promote calcite dissolution. These impacts need to be considered in calcite-based iodate remediation strategies.

Cr(VI) Effect on Tc-99 Removal from Hanford Low-Activity Waste Simulant by Ferrous Hydroxide.

Here, Cr(VI) effects on Tc-immobilization by Fe(OH)2(s) are investigated while assessing Fe(OH)2(s) as a potential treatment method for Hanford low-activity waste destined for vitrification. Batch studies using simulated low-activity waste indicate that Tc(VII) and Cr(VI) removal is contingent on reduction to Tc(IV) and Cr(III). Furthermore, complete removal of both Cr and Tc depends on the amount of Fe(OH)2(s) present, where complete Cr and Tc removal requires more Fe(OH)2(s) (∼200 g/L of simulant), than removing Cr alone (∼50 g/L of simulant). XRD analysis suggests that Fe(OH)2(s) reaction and transformation in the simulant produces mostly goethite (α-FeOOH), where Fe(OH)2(s) transformation to goethite rather than magnetite is likely due to the simulant chemistry, which includes high levels of nitrite and other constituents. Once reduced, a fraction of Cr(III) and Tc(IV) substitute for octahedral Fe(III) within the goethite crystal lattice as supported by XPS, XANES, and/or EXAFS results. The remaining Cr(III) forms oxide and/or hydroxide phases, whereas Tc(IV) not fully incorporated into goethite persists as either adsorbed or partially incorporated Tc(IV)-oxide species. As such, to fully incorporate Tc(IV) into the goethite crystal structure, additional Fe(OH)2(s) (>200 g/L of simulant) may be required.

Reduction and Simultaneous Removal of 99Tc and Cr by Fe(OH)2(s) Mineral Transformation.

Technetium (Tc) remains a priority remediation concern due to persistent challenges, including mobilization due to rapid reoxidation of immobilized Tc, and competing comingled contaminants, e.g., Cr(VI), that inhibit Tc(VII) reduction and incorporation into stable mineral phases. Here Fe(OH)2(s) is investigated as a comprehensive solution for overcoming these challenges, by serving as both the reductant, (Fe(II)), and the immobilization agent to form Tc-incorporated magnetite (Fe3O4). Trace metal analysis suggests removal of Tc(VII) and Cr(VI) from solution occurs simultaneously; however, complete removal and reduction of Cr(VI) is achieved earlier than the removal/reduction of comingled Tc(VII). Bulk oxidation state analysis of the final magnetite solid phase by XANES shows that the majority of Tc is Tc(IV), which is corroborated by XPS measurements. Furthermore, EXAFS results show successful, albeit partial, Tc(IV) incorporation into magnetite octahedral sites. Cr XPS analysis indicates reduction to Cr(III) and the formation of a Cr-incorporated spinel, Cr2O3, and Cr(OH)3 phases. Spinel (modeled as Fe3O4), goethite (α-FeOOH), and feroxyhyte (δ-FeOOH) are detected in all reacted final solid phase samples analyzed by XRD. Incorporation of Tc(IV) has little effect on the spinel lattice structure. Reaction of Fe(OH)2(s) in the presence of Cr(III) results in the formation of a spinel phase that is a solid solution between magnetite (Fe3O4) and chromite (FeCr2O4).

Experimental Determination of Partitioning in the Fe-Ni System for Applications to Modeling Meteoritic Metals.

Experimental trace element partitioning values are often used to model the chemical evolution of metallic phases in meteorites, but limited experimental data were previously available to constrain the partitioning behavior in the basic Fe-Ni system. In this study, we conducted experiments that produced equilibrium solid metal and liquid metal phases in the Fe-Ni system and measured the partition coefficients of 25 elements. The results are in good agreement with values modeled from IVB iron meteorites and with the limited previous experimental data. Additional experiments with low levels of S and P were also conducted, to help constrain the partitioning behaviors of elements as a function of these light elements. The new experimental results were used to derive a set of parameterization values for element solid metal-liquid metal partitioning behavior in the Fe-Ni-S, Fe-Ni-P, and Fe-Ni-C ternary systems at 0.1 MPa. The new parameterizations require that the partitioning behaviors in the light-element-free Fe-Ni system are those determined experimentally by this study, in contrast to previous parameterizations that allowed this value to be determined as a best-fit parameter. These new parameterizations, with self-consistent values for partitioning in the end-member Fe-Ni system, provide a valuable resource for future studies that model the chemical evolution of metallic phases in meteorites.

Accumulation mechanisms for contaminants on weak-base hybrid ion exchange resins.

Mechanism of hexavalent chromium removal (Cr(VI) as CrO42-) by the weak-base ion exchange (IX) resin ResinTech® SIR-700-HP (SIR-700) from simulated groundwater is assessed in the presence of radioactive contaminants iodine-129 (as IO3-), uranium (U as uranyl UO22+), and technetium-99 (as TcO4-), and common environmental anions sulfate (SO42-) and chloride (Cl-). Batch tests using the acid sulfate form of SIR-700 demonstrated Cr(VI) and U(VI) removal exceeded 97%, except in the presence of high SO42- concentrations (536 mg/L) where Cr(VI) and U(VI) removal decreased to ≥ 80%. However, Cr(VI) removal notably improved with co-mingled U(VI) that complexes with SO42- at the protonated amine sites. These U-SO42- complexes are integral to U(VI) removal, as confirmed by the decrease in U(VI) removal (<40%) when the acid chloride form of SIR-700 was used instead. Solid phase characterization revealed that CrO42- is removed by IX with SO42- complexes and/or reduced to amorphous Cr(III)(OH)3 at secondary alcohol sites. Tc(VII)O4- and I(V)O3- also undergo chemical reduction, following a similar removal mechanism. Oxyanion removal preference is determined by the anion reduction potential (CrO42->TcO4->IO3-), geometry, and charge density. For these reasons, 39% and 69% of TcO4- and 17% and 39% of IO3- are removed in the presence and absence of Cr(VI), respectively.

The evolution of hydrated lime-based cementitious waste forms during leach testing leading to enhanced technetium retention.

The interaction between radionuclides and cementitious material phases is crucial in the prediction of the long-term disposal behavior of cementitious waste forms. This work focuses on the behavior of technetium-99 (Tc) within a hydrated-lime based waste form developed as a candidate to immobilize high-sulphate containing liquid wastes known to inhibit cement solidification when using a fly ash based formulation. In leach testing, the hydrated-lime based formulation demonstrated improvement in Tc retention over a fly ash containing formulation beginning after 14 d leaching. The mineralogical evolution of the hydrated-lime samples during leach testing showed a decrease in portlandite content and reduction capacity at the onset of the Tc retention improvement. Leach testing upwards of 400 days showed the improved Tc retention was sustained. Samples cured for different lengths of time (28 days vs 60 days) confirmed that the improved Tc retention and mineralogic change was caused by cement - leachant interactions and not the sample curing time. The Tc observed diffusivities in the hydrated-lime samples are amongst the lowest measured in a cement waste form tested for development at the US Department of Energy Hanford site, leading to a possible pathway to improved cement conditioning where contaminants can be retained for long disposal times.

The behavior of iodine in stabilized granular activated carbon and silver mordenite in cementitious waste forms.

Both granular activated carbon (GAC) and silver mordenite (AgM) are utilized for the removal of contaminants and radionuclides (e.g., radioiodine) from off-gas streams in nuclear fuel reprocessing and high temperature immobilization of nuclear waste. Following their service lifetimes, the GAC and AgM contain an inventory of contaminants and radionuclides and require stabilization in a matrix for disposal. GAC and AgM are referred to as solid secondary waste (SSW) materials. Cementitious waste forms can be used as the stabilization matrix for SSW, however, for successful stabilization, the inclusion of GAC and AgM should not negatively impact the physical behavior of the cementitious waste form or increase release of the contaminants/radionuclides compared to the baseline case without stabilization. The present work focuses on evaluation of cement formulations, with and without slag, for the stabilization of iodine-loaded GAC or AgM. The results showed that both a slag-containing and slag-free formulations were able to stabilize GAC and AgM, up to 30 vol%, without deleterious impacts on the bulk physical properties of the encapsulating matrix. When monolithic samples of the GAC or AgM containing cement formulations were subjected to leach tests, it was observed that iodide leached from the SSW) had limited sorption to either of the cement matrices. Nonetheless, the iodine can interact with the SSW materials themselves. Specifically, iodine retention within monolithic samples containing the iodine-loaded GAC or AgM was improved for AgM containing waste forms while no improvement was observed for the GAC containing waste forms. The improvement for the AgM containing waste forms was likely due to an enrichment of Ag at the interface between the AgM particles and the cement matrix that can impede iodine migration out from the waste form. The results are significant in highlighting the potential for long-term retention of iodine in specific cementitious waste forms.

Metallic technetium sequestration in nickel core/shell microstructure during Fe(OH)2 transformation with Ni doping.

This study investigates the impacts of Ni doping on technetium-99 (Tc) sequestration in aqueous solutions through transformation of Fe(OH)2(s) to iron spinel (magnetite) under alkaline conditions. Extensive solid characterization was performed for the mineral phases produced, as well as the Tc/Ni speciation and distribution within these phases. X-ray diffraction results show that iron spinel was the dominant mineral product without detectable Ni incorporation. The doped Ni ions mainly precipitated as fine Fe/Ni oxide/hydroxide particles, including strongly reduced nanometer-sized spheroidal Ni-rich and metallic Ni phases. High-resolution analytical scanning transmission electron microscopy using energy dispersive X-ray spectroscopy and electron energy loss spectroscopy on the produced solid samples (focused ion beam-prepared specimens) revealed three Tc distribution domains dominated by nanocrystals and, especially, a Tc-rich metallic phase. Instances of metallic Tc were specifically found in spheroidal, Ni-rich and metallic nanoparticles exhibiting a core/shell microstructure that suggests strong reduction and sequential precipitation of Ni-Tc-Ni. Mass balance analysis showed nearly 100% Tc removal from the 4.8 × 10-4 M Tc solutions. The finding of the metallic Tc encapsulation indicates that Tc sequestration through Ni-doped Fe(OH)2(s)-to-iron spinel transformation process likely provides an alternative treatment pathway for Tc removal and could be combined into further waste treatment approaches.

Heteroatom Manipulation of Zeolite Crystallization: Stabilizing Zn-FAU against Interzeolite Transformation.

The preparation of metastable zeolites is often restricted to a limited range of synthesis conditions, which is exemplified in commercial syntheses lacking organics to stabilize the crystal structure. In the absence of an organic structure-directing agent, interzeolite transformation is a common phenomenon that can lead to undesirable products or impurities. Many studies have investigated the substitution of Si and Al in zeolite frameworks with alternative elements (heteroatoms) as a means of tailoring the properties of zeolites; however, relatively few studies have systematically explored the impact of heteroatoms on interzeolite transformations and their concomitant effects on zeolite crystallization. In this study, we examine methods to prepare isostructures of faujasite (FAU), which is one of the most commercially relevant zeolites and also a thermodynamically metastable structure. A survey of multivalent elements revealed that zinc is capable of stabilizing FAU at high temperatures and inhibiting its frequent transformation to zeolite gismondine (GIS). Using combined experimental and computational studies, we show that zinc alters the chemical nature of growth mixtures by sequestering silicates. Zinc heteroatoms incorporate in the FAU framework with a loading-dependent coordination. Our collective findings provide an improved understanding of driving forces for the FAU-to-GIS interzeolite transformation where we observe that heteroatoms (e.g., zinc) can stabilize zeolite FAU over a broad range of synthesis conditions. Given the growing interest in heteroatom-substituted zeolites, this approach to preparing zinc-containing FAU may prove applicable to a broader range of zeolite structures.

Exponential sensitivity and speciation of Al(III), Sc(III), Y(III), La(III), and Gd(III) at fused silica/water interfaces.

The binding contants, adsorption free energies, absolute adsorbate number densities, and interfacial charge densities of Al(III), Sc(III), Y(III), La(III), and Gd(III) interacting with fused silica/water interfaces held at pH 4 were determined using second harmonic generation and the Eisenthal χ((3)) technique. By examining the relationship between the measured adsorption free energies and the electric double layer interfacial potential at multiple electrolyte concentrations, we elucidate the charge state and possible binding pathways for each ion at the fused silica surface. Al(III) and Sc(III) ions are found to bind to the fused silica surface as fully hydrated trivalent species in a bidentate geometry. In contrast, the Y(III), La(III), and Gd(III) ions are each shown to adsorb to the silica surface in a decreased charge state, but the extent and mode of binding varies with each ion. By quantifying the exponential sensitivity of the surface coverage of the adsorbed ions to their charge state directly at the fused silica/water interface, we provide benchmarks for theory calculations describing the interactions of metal ions with oxide interfaces in geochemistry and hope to improve the prediction of trivalent metal ion transport through groundwater environments.

Resolving Configurational Disorder for Impurities in a Low-Entropy Phase.

Hematite (α-Fe2O3) exerts a strong control over the transport of minor but critical metals in the environment and is used in multiple industrial applications; the photocatalysis community has explored the properties of hematite nanoparticles over a wide range of transition metal dopants. Nonetheless, simplistic assumptions are used to rationalize the local coordination environment of impurities in hematite. Here, we use ab initio molecular dynamics (AIMD)-guided structural analysis to model the extended X-ray absorption fine structure (EXAFS) of Cu2+- and Zn2+-doped hematite nanoparticles. Specific defect-impurity associations were identified, and the local coordination environments of Cu and Zn both displayed considerable configurational disorder that, in aggregate, approached Jahn-Teller-like distortion for Cu but, in contrast, maintained hematite-like symmetry for Zn. This study highlights the role of defects in accommodating impurities in a nominally low-entropy phase and the limits to traditional shell-by-shell fitting of EXAFS for dopants/impurities in unprecedented bonding environments.

Vanadium Oxidation States and Structural Role in Aluminoborosilicate Glasses: An Integrated Experimental and Molecular Dynamics Simulation Study.

Vanadium-containing glasses have aroused interest in several fields such as electrodes for energy storage, semiconducting glasses, and nuclear waste disposal. The addition of V2O5, even in small amounts, can greatly alter the physical properties and chemical durability of glasses; however, the structural role of vanadium in these multicomponent glasses and the structural origins of these property changes are still poorly understood. We present a comprehensive study that integrates advanced characterizations and atomistic simulations to understand the composition-structure-property relationships of a series of vanadium-containing aluminoborosilicate glasses. UV-vis spectroscopy, X-ray photoelectron spectroscopy, and X-ray absorption near-edge structure (XANES) have been used to investigate the complex distribution of vanadium oxidation states as a function of composition in a series of six-component aluminoborosilicate glasses. High-energy X-ray diffraction and molecular dynamics simulations were performed to extract the detailed short- and medium-range atomistic structural information such as bond distance, coordination number, bond angle, and network connectivity, based on recently developed vanadium potential parameters. It was found that vanadium mainly exists in two oxidation states: V5+ and V4+, with the former being dominant (∼80% from XANES) in most compositions. V5+ ions were found to exist in 4-, 5-, and 6-fold coordination, while V4+ ions were mainly in 4-fold coordination. The percentage of 4-fold-coordinated boron and network connectivity initially increased with increasing V2O5 up to around 5 mol % but then decreased with higher V2O5 contents. The structural role of vanadium and the effect on glass structure and properties are discussed, providing insights into future studies of sophisticated structural descriptors to predict glass properties from composition and/or structure and aiding the formulation of borosilicate glasses for nuclear waste disposal and other applications.

Spectroscopic and first-principles investigations of iodine species incorporation into ettringite: Implications for iodine migration in cement waste forms.

Low-level radioactive wastes are commonly immobilized in cementitious materials, where cement-based material can incorporate radionuclides into their crystal structure. Specifically, ettringite (Ca6Al2(OH)12(SO4)3∙26H2O) is known to stabilize anionic species, which is appealing for waste streams with radioactive iodine (129I) that persists as iodide (I-) and iodate (IO3-) in the cementitious nuclear waste repository. However, the structural information and immobilization mechanisms of iodine species in ettringite remain unclear. The present results suggested minimal I- incorporation into ettringite (0.05 %), whereas IO3- exhibited a high affinity for ettringite via anion substitution for SO42- (96 %). The combined iodine K-edge extended X-ray absorption fine structure (EXAFS) spectra and first-principles calculations using density functional theory (DFT) suggested that IO3- was stabilized in ettringite by hydrogen bonding and electrostatic forces. Substituting IO3- for SO42- was energetically favorable by -0.41 eV, whereas unfavorable substitution energy of 4.21 eV was observed for I- substitution. Moreover, the bonding charge density analysis of the substituted IO3- and I- anions into the ettringite structure revealed the interaction between intercalated ions with the structural water molecules. These results provided valuable insight into the long-term stabilization of anionic iodine species and their migration in cementitious nuclear waste repository or alkaline environments.

Impact of Cr and Co on 99Tc retention in magnetite: A combined study of ab initio molecular dynamics and experiments.

The effect of co-mingled dopants, Co(II) and Cr(III), on Tc(IV) incorporation and retention in magnetite under varying temperatures (75-700 °C) was explored using ab initio molecular dynamics simulations, batch experiments, and solid phase characterization. Tc(IV) stabilization was achieved with a magnetite surface oversaturated with or containing an equal number of Tc and Cr. Under oversaturation conditions, the forced formation of a Cr2O3 phase on the magnetite surface may help prevent Tc release. Upon Co addition, and depending on the relative concentration of Tc, Cr, and Co at the magnetite surface, Co was found to preferentially stabilize Cr rather than Tc and suppress the formation of the protective Cr2O3 surface phase. Only systems with similar Cr/Co concentrations or relatively high Cr concentrations stabilized Tc within magnetite. As such, the relative concentration of Tc, Cr, and Co was identified as a critical parameter for maximizing dopant efficacy towards Tc stabilization in magnetite.

Technetium immobilization by materials through sorption and redox-driven processes: A literature review.

The objective of this review is to evaluate materials for use as a barrier or other deployed technology to treat technetium-99 (Tc) in the subsurface. To achieve this, Tc interactions with different materials are considered within the context of remediation strategies. Several naturally occurring materials are considered for Tc immobilization, including iron oxides and low solubility sulfide phases. Synthetic materials are also considered, and include tin-based materials, sorbents (resins, activated carbon, modified clays), layered double hydroxides, metal organic frameworks, cationic polymeric networks and aerogels. All of the materials were evaluated for their potential in-situ and ex-situ performance with respect to long-term Tc uptake and immobilization, environmental impacts and deployability. Other factors such as the technology maturity, cost and availability were also considered. Given the difficulty of evaluating materials under different experimental conditions (e.g., solution chemistry, redox conditions, solution to solid ratio, Tc concentration etc.), a subset of these materials will be selected, on the basis of this review, for subsequent standardized batch loading tests.

Iodine immobilization by materials through sorption and redox-driven processes: A literature review.

Radioiodine-129 (129I) in the subsurface is mobile and limited information is available on treatment technologies. Scientific literature was reviewed to compile information on materials that could potentially be used to immobilize 129I through sorption and redox-driven processes, with an emphasis on ex-situ processes. Candidate materials to immobilize 129I include iron minerals, sulfur-based materials, silver-based materials, bismuth-based materials, ion exchange resins, activated carbon, modified clays, and tailored materials (metal organic frameworks (MOFS), layered double hydroxides (LDHs) and aerogels). Where available, compiled information includes material performance in terms of (i) capacity for 129I uptake; (ii) long-term performance (i.e., solubility of a precipitated phase); (iii) technology maturity; (iv) cost; (v) available quantity; (vi) environmental impact; (vii) ability to emplace the technology for in situ use at the field-scale; and (viii) ex situ treatment (for media extracted from the subsurface or secondary waste streams). Because it can be difficult to compare materials due to differences in experimental conditions applied in the literature, materials will be selected for subsequent standardized batch loading tests.

Hybrid Sorbents for 129I Capture from Contaminated Groundwater.

Radioiodine (129I) poses a risk to the environment due to its long half-life, toxicity, and mobility. It is found at the U.S. Department of Energy Hanford Site due to legacy releases of nuclear wastes to the subsurface where 129I is predominantly present as iodate (IO3-). To date, a cost-effective and scalable cleanup technology for 129I has not been identified, with hydraulic containment implemented as the remedial approach. Here, novel high-performing sorbents for 129I remediation with the capacity to reduce 129I concentrations to or below the US Environmental Protection Agency (EPA) drinking water standard and procedures to deploy them in an ex-situ pump and treat (P&T) system are introduced. This includes implementation of hybridized polyacrylonitrile (PAN) beads for ex-situ remediation of IO3--contaminated groundwater for the first time. Iron (Fe) oxyhydroxide and bismuth (Bi) oxyhydroxide sorbents were deployed on silica substrates or encapsulated in porous PAN beads. In addition, Fe-, cerium (Ce)-, and Bi-oxyhydroxides were encapsulated with anion-exchange resins. The PAN-bismuth oxyhydroxide and PAN-ferrihydrite composites along with Fe- and Ce-based hybrid anion-exchange resins performed well in batch sorption experiments with distribution coefficients for IO3- of >1000 mL/g and rapid removal kinetics. Of the tested materials, the Ce-based hybrid anion-exchange resin was the most efficient for removal of IO3- from Hanford groundwater in a column system, with 50% breakthrough occurring at 324 pore volumes. The functional amine groups on the parent resin and amount of active sorbent in the resin can be customized to improve the iodine loading capacity. These results highlight the potential for IO3- remediation by hybrid sorbents and represent a benchmark for the implementation of commercially available materials to meet EPA standards for cleanup of 129I in a large-scale P&T system.