Ankamwar Balaprasad
Department of Chemistry, University of Pune, Ganeshkhind, Pune 411007, India.
J Nanosci Nanotechnol. 2011 May;11(5):3997-4003. doi: 10.1166/jnn.2011.4133.
This study reveals the morphology and polymorphic phase changes of calcium carbonate crystals into a mixture of calcite and aragonite micro/nanocrystals of interesting morphology at room temperature by a simple reaction with fruit extracts of Tamarindus indica and Emblica officinalis respectively by mixing CaCO3 solutions with their corresponding extracts. The control experiments were carried out to establish the plausible role of tartaric acid from Tamarindus indica and ascorbic acid from Emblica officinalis in this regard. The quantitative determination of CaCO3 phases was done based on the use of intensities obtained from corresponding XRD spectrum. The molar % of aragonite was found to be more in case of TA and AA rather than TI and EO respectively, however the calcite was observed to be the predominant phase in all four reactions. Interestingly, the TI changes the rhombohedral morphology of calcite to elongated rods, whereas EO induces a great polymorphic phase change.
本研究揭示了通过分别将碳酸钙溶液与罗望子和余甘子的果实提取物混合，在室温下碳酸钙晶体的形态以及向方解石和文石微/纳米晶体混合物的多晶型相变，这两种晶体具有有趣的形态。进行了对照实验以确定罗望子中的酒石酸和余甘子中的抗坏血酸在这方面的可能作用。基于从相应X射线衍射光谱获得的强度对碳酸钙相进行定量测定。结果发现，在酒石酸（TA）和抗坏血酸（AA）的情况下，文石的摩尔百分比分别高于罗望子提取物（TI）和余甘子提取物（EO），然而在所有四个反应中均观察到方解石是主要相。有趣的是，罗望子提取物将方解石的菱面体形态变为细长棒状，而余甘子提取物则引起了很大的多晶型相变。
