Shaikh Nabil, Qian Jiajie, Kim Sewoon, Phan Hoa, Lezama-Pacheco Juan S, Ali Abdul-Mehdi S, Cwiertny David M, Forbes Tori Z, Haes Amanda J, Cerrato José M
Department of Civil, Construction, & Environmental Engineering, University of New Mexico, MSC01 1070, Albuquerque, NM 87131, USA.
Department of Civil and Environmental Engineering, University of Iowa, Iowa City IA52242, USA.
J Environ Chem Eng. 2022 Oct;10(5). doi: 10.1016/j.jece.2022.108448. Epub 2022 Aug 17.
We previously observed that phosphonate functionalized electrospun nanofibers can uptake U(VI), making them promising materials for sensing and water treatment applications. Here, we investigate the optimal fabrication of these materials and their mechanism of U(VI) binding under the influence of environmentally relevant ions (e.g., Ca and ). We found that U(VI) uptake was greatest on polyacrylonitrile (PAN) functionalized with longer-chain phosphonate surfactants (e.g., hexa- and octadecyl phosphonate; HDPA and ODPA, respectively), which were better retained in the nanofiber after surface segregation. Subsequent uptake experiments to better understand specific solid-liquid interfacial interactions were carried out using 5 mg of HDPA-functionalized PAN mats with 10 μM U at pH 6.8 in four systems with different combinations of solutions containing 5 mM calcium (Ca) and 5 mM bicarbonate ( ). U uptake was similar in control solutions containing no Ca and (resulting in 19 ± 3% U uptake), and in those containing only 5 mM Ca (resulting in 20 ± 3% U uptake). A decrease in U uptake (10 ± 4% U uptake) was observed in experiments with , indicating that UO-CO complexes may increase uranium solubility. Results from shell-by-shell EXAFS fitting, aqueous extractions, and surface-enhanced Raman scattering (SERS) indicate that U is bound to phosphonate as a monodentate inner sphere surface complex to one of the hydroxyls in the phosphonate functional groups. New knowledge derived from this study on material fabrication and solid-liquid interfacial interactions will help to advance technologies for use in the in-situ detection and treatment of U in water.
我们之前观察到，膦酸盐功能化的电纺纳米纤维可以摄取U(VI)，使其成为传感和水处理应用中有前景的材料。在此，我们研究了这些材料的最佳制备方法及其在环境相关离子（如Ca和 ）影响下对U(VI)的结合机制。我们发现，在用较长链膦酸盐表面活性剂（分别为六烷基膦酸盐和十八烷基膦酸盐；HDPA和ODPA）功能化的聚丙烯腈（PAN）上，U(VI)的摄取量最大，这些表面活性剂在表面偏析后能更好地保留在纳米纤维中。随后，使用5毫克HDPA功能化的PAN垫，在pH 6.8的条件下，于含有5毫摩尔钙（Ca）和5毫摩尔碳酸氢盐（ ）的不同溶液组合的四个系统中，与10微摩尔U进行摄取实验，以更好地理解特定的固液界面相互作用。在不含Ca和 的对照溶液中（U摄取率为19±3%）以及仅含有5毫摩尔Ca的溶液中（U摄取率为20±3%），U的摄取情况相似。在含有 的实验中观察到U摄取量下降（U摄取率为10±4%），这表明UO-CO络合物可能会增加铀的溶解度。逐壳EXAFS拟合、水相萃取和表面增强拉曼散射（SERS）的结果表明，U以单齿内球表面络合物的形式与膦酸盐功能基团中的一个羟基结合。这项关于材料制备和固液界面相互作用的研究获得的新知识将有助于推动水中U原位检测和处理技术的发展。
