Stability, morphological transformation and flocculability investigation of planar tridecameric Al13(OH)24(H2O)2415+
Stability, morphological transformation and flocculability investigation of planar tridecameric Al13(OH)24(H2O)2415+
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平面十三聚体Al-13(OH)(24)(H2O)(24)(15)的稳定性、形态转变和絮凝性研究
DOI：
10.1016/j.seppur.2017.04.033
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发表时间：
2017-08-31
影响因子：
8.6
通讯作者：
Sun, Zhong
中科院分区：
文献类型：
--
作者：
Guo, Tingting;Chen, Rongxuan;Sun, Zhong
尽管人们在制备平面Al-13 [Al-13(OH)(24)(H2O)(24)(15+), M-Al-13]方面付出了巨大的努力，但对其在水溶液中的稳定性和水解行为的了解的缺乏限制了其作为混凝剂的实际应用。本研究对M-Al-13的稳定性、形态转变和混凝性能进行了深入研究。 Al-27-NMR 谱揭示了水溶液中从 M-Al-13 到 K-Al-13 的温度依赖性形态转变。这种转变在5℃以下完全被抑制，但随着温度从5℃升高到70℃而加速。此外，更高的温度和更长的老化时间导致K-Al-13进一步转变为具有更高聚合度的铝物种，例如Al-30。因此，低温有利于M Al-13的形态稳定性。由于M-Al-13结构的保持，所有制备的M-Al-13晶体、M-Al-13溶液（0℃）和冷冻干燥的M-Al-13在絮体生长速率、絮体尺寸和絮体强度方面均表现出优异且可比的絮凝性能。有趣的是，M Al-13溶液在25℃和40℃老化120分钟后，絮凝性急剧下降，分别有29％和62％的M-Al-13转化为K-Al-13。这些结果表明M-Al-13是一种重要的絮凝剂，其性能优于众所周知的高效絮凝剂K-Al-13。我们对 M Al-13 稳定性和水解行为的研究可能会促进其作为高效水净化絮凝剂的应用。 (C) 2017 Elsevier B.V. 保留所有权利。
Though great efforts have devoted to prepare planar Al-13 [Al-13(OH)(24)(H2O)(24)(15+), M-Al-13], the lack of knowledge of its stability and hydrolysis behavior in aqueous solution limits its practical application as coagulant. In this study, the stability, morphological transformation and coagulation property of M-Al-13 were thoroughly investigated. The Al-27-NMR spectra revealed temperature-dependent morphological transformation from M-Al-13 to K-Al-13 in aqueous solution. This transformation was completely inhabited below 5 degrees C, but was accelerated with increased temperature from 5 to 70 degrees C. Moreover, higher temperature and longer aging time led to further transformation of K-Al-13 to the aluminum species with higher degree of polymerization such as Al-30. Thus, low temperature was favorable for the morphological stability of M Al-13. Due to the maintenance of M-Al-13 structure, all as-prepared M-Al-13 crystal, M-Al-13 solution (0 degrees C) and freeze dried M-Al-13 showed excellent and comparable flocculation property in the terms of floc growth rate, floc size and floc strength. Interestingly, the flocculability dramatically decreased after M Al-13 solution aged at 25 degrees C or 40 degrees C for 120 min with 29% and 62% of M-Al-13 transformed to K-Al-13, respectively. These results implied that M-Al-13 was an important flocculant with better performance than the well-known and efficient flocculant K-Al-13. Our study about the stability and hydrolysis behavior of M Al-13 might prompt its application as a highly efficient flocculent for water purification. (C) 2017 Elsevier B.V. All rights reserved.