کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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609747 | 880629 | 2010 | 6 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Synthesis and characterization of calcite and aragonite in polyol liquids: Control over structure and morphology Synthesis and characterization of calcite and aragonite in polyol liquids: Control over structure and morphology](/preview/png/609747.png)
An innovative precipitation process, achieved through the thermal decomposition of urea in polyols containing hydrated calcium salts, was used to prepare calcite and aragonite at elevated temperatures (120–180 °C). The effect of various experimental conditions, such as the media of different polyols (ethylene glycol, EG; diethylene glycol, DEG; and tetraethylene glycol, TEG), the temperature, the reaction time, and the addition of magnesium salts, on the structure, size, and morphology of the obtained solids is described. It was found that the formation of calcium carbonate polymorphs, i.e., calcite or aragonite, their morphology and their size was predominantly influenced by the type of polyols used, and by the diverse growing mechanisms occurring in the different polyol systems. Structurally and morphologically different calcite precipitates were formed in the DEG and TEG solvents via classical crystallization processes, while colloidal and nanostructured aragonite particles were assembled in the EG through a recently reaffirmed mechanism based on the role of nanoscale aggregation processes in the formation of carbonate solids. This study highlights the importance of the presence and concentration of magnesium ions in the inhibition of the crystal growth of nanosized aragonite, and in the stabilization of amorphous calcium carbonate (ACC) precipitates in polyol solutions.
SEM photomicrograph of aragonite obtained by aging EG solutions containing 0.75 mol dm−3 urea, 0.25 mol dm−3 CaCl2 at 160 °C for 10 min.Figure optionsDownload high-quality image (148 K)Download as PowerPoint slide
Journal: Journal of Colloid and Interface Science - Volume 347, Issue 2, 15 July 2010, Pages 221–226