Filtration Suppresses Laser-Induced Nucleation of Glycine in Aqueous Solutions
Filtration Suppresses Laser-Induced Nucleation of Glycine in Aqueous Solutions
复制标题
DOI：
10.1021/acs.cgd.6b00046
复制
发表时间：
2016-08-01
影响因子：
3.8
通讯作者：
Sefcik, Jan
中科院分区：
文献类型：
--
作者：
Javid, Nadeem;Kendall, Thomas;Sefcik, Jan
我们表明，纳米过滤的甘氨酸水溶液具有显着的影响，激光诱导成核。两个成核制度中观察到的非过滤，照射的解决方案在等温条件下：一个快速的初始制度与激光诱导成核和第二个慢得多的自发成核制度。照射前过滤的解决方案大大抑制了快速政权，而缓慢的政权是类似的，无论过滤或照射，所有的过饱和度研究。还观察到过滤对晶体多晶型的明显影响。未经过滤的辐照溶液在较低的过饱和度几乎完全产生的α-多晶型，而在较高的过饱和度有显着的存在（类似于40%）的γ-多晶型。另一方面，过滤的溶液几乎完全产生在所有研究的过饱和度的甘氨酸的α-多晶型物。这些令人惊讶的结果挑战了一些关于激光诱导成核的既定观点，表明先前报道的激光诱导成核。甘氨酸水溶液中的成核现象可以通过过滤有效地抑制，因此潜在的机理不太可能基于仅涉及溶质和溶剂的分子尺度相互作用。相反，在这个系统中的激光诱导成核似乎是有关的胶体规模的解决方案集群或外来的固体或分子杂质，可以通过纳滤去除。
We demonstrate that nanofiltration of aqueous glycine solutions has a pronounced effect on laser-induced nucleation. Two nucleation regimes were observed in nonfiltered, irradiated solutions under isothermal conditions: a rapid initial regime associated with laser-induced nucleation and a second much slower spontaneous nucleation regime. Filtration of the solutions prior to irradiation greatly suppressed the rapid regime, while the slow regime was similar regardless of filtration or irradiation, for all supersaturations studied. A clear effect of filtration on crystal polymorphism was also observed. Nonfiltered irradiated solutions at a lower supersaturation almost exclusively yielded the alpha-polymorph, while at higher supersaturations there was significant presence (similar to 40%) of the gamma-polymorph. On the other hand, filtered solutions almost exclusively yielded the alpha-polymorph of glycine at all supersaturations studied. These surprising results challenge some established ideas about laser-induced nucleation, showing that previously reported laser-induced. nucleation phenomena in glycine aqueous solutions can be effectively suppressed by filtration, so that the underlying mechanism is unlikely to be based on molecular scale interactions involving just the solute and the solvent alone. Instead, laser-induced nucleation in this system appears to be related to either colloidal scale solution clusters or foreign solid or molecular impurities that can be removed by nanofiltration.