Dubovoy Viktor, Subramanyam Ravi, Stranick Michael, Du-Thumm Laurence, Pan Long
Colgate-Palmolive Company.
Colgate-Palmolive Company;
J Vis Exp. 2017 May 11(123):55423. doi: 10.3791/55423.
An aqueous suspension of nanogibbsite was synthesized via the titration of aluminum aqua acid [Al(H2O)6] with L-arginine to pH 4.6. Since the hydrolysis of aqueous aluminum salts is known to produce a wide array of products with a wide range of size distributions, a variety of state-of-the-art instruments (i.e., Al/H NMR, FTIR, ICP-OES, TEM-EDX, XPS, XRD, and BET) were used to characterize the synthesis products and identification of byproducts. The product, which was comprised of nanoparticles (10-30 nm), was isolated using gel permeation chromatography (GPC) column technique. Fourier transform infrared (FTIR) spectroscopy and powder X-ray diffraction (PXRD) identified the purified material as the gibbsite polymorph of aluminum hydroxide. The addition of inorganic salts (e.g., NaCl) induced electrostatic destabilization of the suspension, thereby agglomerating the nanoparticles to yield Al(OH)3 precipitate with large particle sizes. By utilizing the novel synthetic method described here, Al(OH)3 was partially loaded inside the highly ordered mesoporous framework of MCM-41, with average pore dimensions of 2.7 nm, producing an aluminosilicate material with both octahedral and tetrahedral Al (Oh/Td = 1.4). The total Al content, measured using energy-dispersive X-ray spectrometry (EDX), was 11% w/w with a Si/Al molar ratio of 2.9. A comparison of bulk EDX with surface X-ray photoelectron spectroscopy (XPS) elemental analysis provided insight into the distribution of Al within the aluminosilicate material. Furthermore, a higher ratio of Si/Al was observed on the external surface (3.6) as compared to the bulk (2.9). Approximations of O/Al ratios suggest a higher concentration of Al(O)3 and Al(O)4 groups near the core and external surface, respectively. The newly developed synthesis of Al-MCM-41 yields a relatively high Al content while maintaining the integrity of the ordered silica framework and can be used for applications where hydrated or anhydrous Al2O3 nanoparticles are advantageous.
通过用L-精氨酸将铝水合酸[Al(H₂O)₆]滴定至pH 4.6，合成了纳米三水铝石的水悬浮液。由于已知铝盐水解会产生具有广泛尺寸分布的多种产物，因此使用了各种先进仪器（即Al/H NMR、FTIR、ICP-OES、TEM-EDX、XPS、XRD和BET）来表征合成产物并鉴定副产物。使用凝胶渗透色谱（GPC）柱技术分离出由纳米颗粒（10 - 30 nm）组成的产物。傅里叶变换红外（FTIR）光谱和粉末X射线衍射（PXRD）确定纯化后的材料为氢氧化铝的三水铝石多晶型物。添加无机盐（例如NaCl）会引起悬浮液的静电失稳，从而使纳米颗粒团聚，产生大粒径的Al(OH)₃沉淀。通过采用此处所述的新型合成方法，Al(OH)₃被部分负载在平均孔径为2.7 nm的高度有序介孔MCM-41骨架内，生成了具有八面体和四面体Al（Oh/Td = 1.4）的硅铝酸盐材料。使用能量色散X射线光谱法（EDX）测得的总Al含量为11% w/w，Si/Al摩尔比为2.9。将体相EDX与表面X射线光电子能谱（XPS）元素分析进行比较，有助于深入了解Al在硅铝酸盐材料中的分布情况。此外，与体相（2.9）相比，在外表面观察到更高的Si/Al比（3.6）。O/Al比的近似值表明，分别在核心和外表面附近Al(O)₃和Al(O)₄基团的浓度较高。新开发的Al-MCM-41合成方法在保持有序二氧化硅骨架完整性的同时产生了相对较高的Al含量，可用于水合或无水Al₂O₃纳米颗粒具有优势的应用中。
