Institute of Materials Engineering and ANSTO Minerals, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, New South Wales 2232, Australia.
ACS Appl Mater Interfaces. 2010 Dec;2(12):3436-46. doi: 10.1021/am100891u. Epub 2010 Nov 12.
A series of functional hybrid inorganic-organic adsorbent materials have been prepared through postsynthetic grafting of mesoporous zirconium titanate xerogel powders using a range of synthesized and commercial mono-, bis-, and tris-phosphonic acids, many of which have never before been investigated for the preparation of hybrid phases. The hybrid materials have been characterized using thermogravimetric analysis, diffuse reflectance infrared (DRIFT) and 31P MAS NMR spectroscopic techniques and their adsorption properties studied using a 153Gd radiotracer. The highest level of surface functionalization (molecules/nm2) was observed for methylphosphonic acid (∼3 molecules/nm2). The level of functionalization decreased with an increase in the number of potential surface coordinating groups of the phosphonic acids. Spectral decomposition of the DRIFT and 31P MAS NMR spectra showed that each of the phosphonic acid molecules coordinated strongly to the metal oxide surface but that for the 1,1-bis-phosphonic acids and tris-phosphonic acids the coordination was highly variable resulting in a proportion of free or loosely coordinated phosphonic acid groups. Functionalization of a porous mixed metal oxide framework with the tris-methylenephosphonic acid (ATMP-ZrTi-0.33) resulted in a hybrid with the highest affinity for 153Gd3+ in nitric acid solutions across a wide range of acid concentrations. The ATMP-ZrTi-0.33 hybrid material extracted 153Gd3+ with a Kd value of 1×10(4) in 0.01 M HNO3 far exceeding that of the other hybrid phases. The unfunctionalized mesoporous mixed metal oxide had negligible affinity for Gd3+ (Kd<100) under identical experimental conditions. It has been shown that the presence of free or loosely coordinated phosphonic acid groups does not necessarily translate to affinity for 153Gd3+. The theoretical cation exchange capacity of the ATMP-ZrTi-0.33 hybrid phase for Gd3+ has been determined to be about 0.005 mmol/g in 0.01 M HNO3. This behavior and that of the other hybrid phases suggests that the surface-bound ATMP ligand functions as a chelating ligand toward 153Gd3+ under these acidic conditions.
已经通过在介孔钛酸锆干凝胶粉末上进行后合成接枝，制备了一系列功能化的杂化无机-有机吸附剂材料。使用了一系列合成的和商业的单、双和三膦酸，其中许多膦酸以前从未被用于制备杂化相。通过热重分析、漫反射红外（DRIFT）和 31P MAS NMR 光谱技术对杂化材料进行了表征，并使用 153Gd 放射性示踪剂研究了它们的吸附性质。在甲膦酸（约 3 个分子/nm2）中观察到最高的表面官能化水平（分子/nm2）。官能化水平随着膦酸中潜在表面配位基团数量的增加而降低。DRIFT 和 31P MAS NMR 光谱的光谱分解表明，每个膦酸分子都与金属氧化物表面强烈配位，但对于 1,1-双膦酸和三膦酸，配位高度可变，导致一部分游离或松散配位的膦酸基团。用三亚甲基膦酸（ATMP-ZrTi-0.33）对多孔混合金属氧化物骨架进行功能化，得到了在很宽的酸浓度范围内对硝酸溶液中的 153Gd3+具有最高亲和力的杂化材料。ATMP-ZrTi-0.33 杂化材料在 0.01 M HNO3 中以 1×10(4)的 Kd 值提取 153Gd3+，远远超过其他杂化相。在相同实验条件下，未功能化的介孔混合金属氧化物对 Gd3+几乎没有亲和力（Kd<100）。已经表明，游离或松散配位的膦酸基团的存在不一定转化为对 153Gd3+的亲和力。ATMP-ZrTi-0.33 杂化相在 0.01 M HNO3 中对 Gd3+的理论阳离子交换容量约为 0.005 mmol/g。这种行为和其他杂化相的行为表明，在这些酸性条件下，表面结合的 ATMP 配体对 153Gd3+ 起螯合配体的作用。
