Nanoporous zirconium phosphonate (ZrP) materials are considered to be promising candidates for practical applications such as catalysis and separation, in particular because of their excellent stability, resulting from the strength of the P–O–Zr bond. However, the functionality of ZrP materials is dependent on the availability of free phosphonate groups uncoordinated by zirconium, the presence of which can decrease the stability. The mechanisms by which nanoporous ZrP materials degrade and lose functionality during thermal and chemical treatment are not well understood. Herein, we address this knowledge gap using nanoporous zirconium aminotris(methylenephosphonic acid) (Zr-ATMP) sorbent materials. Thermal treatment up to 150 °C caused collapse of the nanoporous structure of some Zr-ATMP materials without a significant effect on the chemical structure. On the other hand, contact with 5 M nitric acid changed the chemical structure of the Zr-ATMP materials by catalyzing the formation of P–O–Zr bonds and elemental leaching. Enhancement of the thermal and chemical stability of the Zr-ATMP materials was achieved by decreasing the pH of the synthesis and, interestingly, changing the counterion of the hydroxide used to control the pH also impacted the structure and stability of the resulting materials. The most stable Zr-ATMP material was produced at pH 3 using LiOH, but this material demonstrated lower selectivity than other Zr-ATMP materials, which decreases its practicality for separation applications. The Zr-ATMP material synthesized at pH 3 with NaOH showed an optimal balance between the stability and sorption performance. The enhanced chemical and thermal stability of this material drastically improves its applicability for use in harsh environments, such as in the treatment of radioactive wastes.

中文翻译：

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具有增强的化学和热稳定性的纳米多孔磷酸锆材料，用于吸附剂应用

纳米多孔膦酸锆（ZrP）材料被认为是诸如催化和分离之类的实际应用的有前途的候选者，尤其是由于P–O–Zr键的强度而具有出色的稳定性。然而，ZrP材料的功能性取决于锆不配位的游离膦酸酯基团的可用性，其存在会降低稳定性。纳米多孔ZrP材料在热处理和化学处理过程中降解并丧失功能性的机制尚不清楚。在本文中，我们使用纳米多孔氨基三（锆膦酸）（Zr-ATMP）吸附剂材料解决了这一知识空白。高达150°C的热处理导致某些Zr-ATMP材料的纳米孔结构崩溃，而对化学结构没有明显影响。另一方面，与5 M硝酸接触会通过催化P–O–Zr键的形成和元素浸出而改变Zr-ATMP材料的化学结构。Zr-ATMP材料的热稳定性和化学稳定性的提高是通过降低合成的pH值实现的，有趣的是，改变用于控制pH值的氢氧化物的抗衡离子也影响所得材料的结构和稳定性。使用LiOH在pH 3下生产最稳定的Zr-ATMP材料，但该材料的选择性比其他Zr-ATMP材料低，这降低了其在分离应用中的实用性。用NaOH在pH 3下合成的Zr-ATMP材料显示出稳定性和吸附性能之间的最佳平衡。这种材料增强的化学和热稳定性极大地提高了其在恶劣环境（例如放射性废物处理）中使用的适用性。