Saslow Sarah A, Cordova Elsa A, Escobedo Nancy M, Qafoku Odeta, Bowden Mark E, Resch Charles T, Lahiri Nabajit, Nienhuis Emily T, Boglaienko Daria, Levitskaia Tatiana G, Meyers Peter, Hager Jacqueline R, Emerson Hilary P, Pearce Carolyn I, Freedman Vicky L
Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland 99354, WA, USA.
Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland 99354, WA, USA.
J Hazard Mater. 2023 Oct 5;459:132165. doi: 10.1016/j.jhazmat.2023.132165. Epub 2023 Jul 26.
Mechanism of hexavalent chromium removal (Cr(VI) as CrO) 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 IO), uranium (U as uranyl UO), and technetium-99 (as TcO), and common environmental anions sulfate (SO) 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 SO 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 SO at the protonated amine sites. These U-SO 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 CrO is removed by IX with SO complexes and/or reduced to amorphous Cr(III)(OH) at secondary alcohol sites. Tc(VII)O and I(V)O also undergo chemical reduction, following a similar removal mechanism. Oxyanion removal preference is determined by the anion reduction potential (CrO>TcO>IO), geometry, and charge density. For these reasons, 39% and 69% of TcO and 17% and 39% of IO are removed in the presence and absence of Cr(VI), respectively.
在放射性污染物碘 - 129（以IO形式存在）、铀（以铀酰UO形式存在的U）和锝 - 99（以TcO形式存在）以及常见环境阴离子硫酸根（SO）和氯离子（Cl）存在的情况下，评估了弱碱性离子交换（IX）树脂ResinTech® SIR - 700 - HP（SIR - 700）从模拟地下水中去除六价铬（Cr(VI) 以CrO形式存在）的机制。使用SIR - 700的酸性硫酸根形式进行的批次试验表明，Cr(VI) 和U(VI) 的去除率超过97%，但在高SO浓度（536 mg/L）存在的情况下，Cr(VI) 和U(VI) 的去除率降至≥80%。然而，与质子化胺位点处的SO络合的混合U(VI) 显著提高了Cr(VI) 的去除率。这些U - SO络合物对于U(VI) 的去除至关重要，这一点通过使用SIR - 700的酸性氯离子形式时U(VI) 去除率下降（<40%）得到证实。固相表征显示，CrO通过IX与SO络合物一起被去除和/或在仲醇位点被还原为无定形Cr(III)(OH)。Tc(VII)O和I(V)O也遵循类似的去除机制进行化学还原。含氧阴离子的去除偏好由阴离子还原电位（CrO>TcO>IO）、几何形状和电荷密度决定。因此，在存在和不存在Cr(VI) 的情况下，分别有39%和69%的TcO以及17%和39%的IO被去除。
