Characterisation of properties of various halloysites relevant to their use as nanotubes and microfibre fillers
Characterisation of properties of various halloysites relevant to their use as nanotubes and microfibre fillers
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DOI：
10.1016/j.clay.2012.06.014
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发表时间：
2013-04-01
影响因子：
5.6
通讯作者：
Keeling, John L.
中科院分区：
文献类型：
--
作者：
Pasbakhsh, Pooria;Churchman, G. Jock;Keeling, John L.
对粘土矿物埃洛石的新工业应用的研究兴趣日益增加，其中更多地利用其天然管状形态，纳米级直径和内外表面上的对比化学。埃洛石纳米管，通常称为HNT，具有作为微纤维填料、用于在纳米反应器或纳米模板中供应和控制或持续释放用于药物递送和防腐蚀涂层的活性剂的载体以及用于吸收污染物或污染物的潜在应用。在这项研究中，各种性质的测量6埃洛石从不同的地理和地质环境，澳大利亚，新西兰和美国。根据结果，推断出它们对新用途的相对适用性。表征包括通过X射线衍射（XRD），形态，表面积和孔体积的杂质鉴定电子显微镜和氮吸收，可交换阳离子的测定，和zeta电位的测量在很宽的pH值范围内。在个别样品中埃洛石含量范围为84至98%。杂质包括少量石英、方石英、高岭石、三水铝石、明矾石、氧化铁和碳酸氢钠。埃洛石形态和杂质水平的变化对表面积和内部孔体积的影响最大。具有低水平杂质和常规薄壁管的样品报告了与埃洛石管中的圆柱形腔或管腔相关的最高孔体积。表面积为22 - 81 m2.g-1，与HNT内腔相关的孔隙比例为11 - 39%。当6种不同埃洛石的性能相对于埃洛石作为纳米管用于添加剂或载体的要求进行评估时，其中一种显示出两种类型应用的特殊特性，但它很少发生。另一种埃洛石适度适合用作添加剂而不是载体，其存在于大的存款中。其他样品各自显示出用作添加剂和/或载体的适用性的一些限制。(C)2012爱思唯尔有限公司版权所有。
There is increasing research interest on new industrial applications for the clay mineral halloysite where greater use is made of its natural tubular morphology, nano-scale diameter and contrasting chemistry on external and internal surfaces. Halloysite nanotubes, commonly referred to as HNTs, have potential applications as microfibre fillers, carriers for the supply and controlled or sustained release of active agents for drug delivery and anticorrosion coatings, in nanoreactors or nanotemplates, and for the uptake of contaminants or pollutants. In this study, various properties were measured on 6 halloysites from different geographical and geological environments from Australia, New Zealand and the USA. From the results, inferences were drawn on their comparative suitability for new uses. The characterisation included identification of impurities by X-ray diffraction (XRD), morphology, surface area and pore volume by electron microscopy and nitrogen absorption, the determination of exchangeable cations, and measurement of zeta potential over a wide range of pH. Halloysite content in individual samples ranged from 84 to 98%. Impurities included minor quartz, cristobalite, kaolinite, gibbsite, alunite, iron oxides and anatase. Variation in halloysite morphology and the levels of impurities had the most effect on surface area and internal pore volume. Samples with low levels of impurities and regular, thin-walled tubes reported the highest pore volumes associated with the cylindrical cavity or lumen in halloysite tubes. Surface areas varied from 22 to 81 m(2).g(-1) and the proportion of pore space associated with the HNT lumen ranged from 11 to 39%. When the properties of the 6 different halloysites were assessed relative to the requirements for halloysite as nanotubes for either additives or carriers, one showed exceptional characteristics for both types of application but it occurs only rarely. Another halloysite that is moderately suitable for use as an additive but not a carrier occurs in a large deposit. The other samples each showed some limitations of suitability for use as an additive and/or as a carrier. (C) 2012 Elsevier B.V. All rights reserved.