Abstract

A method for the surface chemical modification of aluminum oxyhydroxide (boehmite γ-AlO (OH)) by the nitrilotris(methylene phosphonic) acid (NTP) complexing ligand is proposed. The unmodified and NTP-modified boehmites are characterized using X-ray powder diffraction, XPS, and IR spectroscopy; the acid–base and complex-forming properties of surface-grafted NTP are studied. One of the three phosphonic groups of NTP is found to be involved in binding to the boehmite surface. The surface concentration and stepwise dissociation constants of grafted NTP are determined. A study of the nickel(II) sorption as a function of aqueous acidity shows that the modifying coating increases the sorption capacity of boehmite (causing рН₅₀ to shift by one unit toward lower values). In terms of surface complexation theory, nickel(II) sorption from aqueous solutions may be described by models involving ≡Al–ONi⁺ and ≡Al–ONi(OH) complexes in the case of boehmite and ≡Al–LH_i Ni^i–3 (i = 0, 1, 2, or 3) complexes in the case of NTP-modified boehmite (NTP-boehmite). NTP anchorage to the surface decreases the stability of nickel(II) complexes compared to their analogues in solutions. A mechanism of nickel(II) ion binding by NTP-boehmite is suggested. The prepared new organomineral support can be used to immobilize those metal ions that form stable complexes with phosphonic acids.

中文翻译：

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基于硝酸腈（亚甲基膦酸）修饰的氢氧化铝的新型复合物有机载体

摘要

提出了一种亚硝基三（亚甲基膦酸）络合配体对氢氧化铝（勃姆石γ-AlO（OH））进行表面化学改性的方法。未修饰的和NTP修饰的勃姆石使用X射线粉末衍射，XPS和IR光谱进行表征；研究了表面接枝NTP的酸碱和形成配合物的性质。发现NTP的三个膦酸基团之一参与与勃姆石表面的结合。确定了接枝NTP的表面浓度和逐步解离常数。镍的研究（II）吸附作为水性酸度示出了功能，该修改涂层增加勃姆石的吸附容量（导致рН ₅₀向较低的值移动一个单位）。根据表面络合理论，在勃姆石和≡Al–LH _i Ni ^{i –3}的情况下，可以用涉及≡Al–ONi ⁺和≡Al–ONi（OH）配合物的模型描述水溶液中镍（II）的吸附。在NTP改性勃姆石（NTP-勃姆石）的情况下（i = 0、1、2或3）络合物。与溶液中的类似物相比，NTP在表面的锚固降低了镍（II）配合物的稳定性。提出了NTP-勃姆石结合镍离子的机理。制备的新的有机矿物载体可用于固定那些与膦酸形成稳定络合物的金属离子。