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首页> 外文期刊>RSC Advances >Improvement of boehmite nanoparticles' aqueous dispersability by controlling their size, shape and crystallinity
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Improvement of boehmite nanoparticles' aqueous dispersability by controlling their size, shape and crystallinity

机译：通过控制尺寸，形状和结晶度来改善勃姆石纳米颗粒的水分散性

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In this work, results on the control of size, shape, crystallinity and aqueous dispersability of boehmite prepared by a hydrothermal process are reported. The two step synthetic procedure entailed the precipitation of a xerogel by adding NaOH until pH 10 to a solution of aluminum nitrate at 100 degrees C without or with additives such as tartaric acid and maltitol, and a subsequent hydrothermal treatment at 150 and 200 degrees C for different periods of time. The final materials were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and elemental analysis. The stability and other characteristics of the boehmite nanoparticle aqueous dispersions were determined by measuring the zeta potential (zeta), and the particle size distribution (PSD) by dynamic light scattering (DLS). Additive-free boehmite hydrothermally processed at 150 degrees C for 24 h displayed average lengths of around 20 nm. On increasing the temperature to 200 degrees C and the holding time up to 168 h, both the particle length increased (ca. 95 nm) and the particle size distribution widened. Comparatively, the growth of the boehmite nanoparticles in the samples prepared with additives was severely restricted up to 20% of the length of additive-free obtained particles, leading to narrower particle size distributions. Modifications in their shape were also allowed. Interestingly, improved aqueous dispersion stabilities were observed for samples prepared in the presence of an additive. A higher dispersability over a wide pH window was found in maltitol-grafted boehmite nanoparticle dispersions with hydrodynamic sizes closer to the single-particle sizes, as observed by TEM. The different formation and stabilization mechanisms of the boehmite nanoparticles obtained in the presence of additives through the synthetic procedure are also discussed.
机译：在这项工作中，报道了通过水热法制备的勃姆石的尺寸，形状，结晶度和水分散性的控制结果。两步合成过程需要在不添加或添加酒石酸和麦芽糖醇等添加剂的情况下，在100℃下向硝酸铝溶液中添加NaOH直到pH为10，从而干燥凝胶，然后在150和200℃下进行水热处理不同的时间段。最终材料通过透射电子显微镜（TEM），X射线衍射（XRD）和元素分析进行​​表征。通过测量ζ电势（ζ）和通过动态光散射（DLS）测量粒度分布（PSD）来确定勃姆石纳米颗粒水分散体的稳定性和其他特性。在150摄氏度下水热处理24小时的无添加剂勃姆石显示出约20 nm的平均长度。将温度提高到200摄氏度，保持时间长达168小时，颗粒长度均增加了（约95 nm），粒径分布也变宽了。相比之下，在用添加剂制备的样品中勃姆石纳米颗粒的生长受到严格限制，达到了不含添加剂的颗粒长度的20％，从而导致粒度分布变窄。也可以对其形状进行修改。有趣的是，对于在添加剂存在下制备的样品，观察到改善的水分散稳定性。 TEM观察到，在流体动力学尺寸更接近单颗粒尺寸的麦芽糖醇接枝勃姆石纳米颗粒分散体中，在宽的pH窗口中发现了更高的分散性。还讨论了在添加剂存在下通过合成程序获得的勃姆石纳米颗粒的不同形成和稳定机制。

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