成核
过饱和度
化学
异丙醇
表面张力
分析化学(期刊)
临界半径
结晶学
无机化学
化学工程
色谱法
热力学
有机化学
几何学
物理
工程类
曲率
数学
作者
S. Sandhya,S. Sureshbabu,H. K. Varma,Manoj Komath
标识
DOI:10.1002/crat.201200098
摘要
Calcium sulfate dihydrate, constituted as uniform crystals of low dimensions, is a potential biomaterial for clinical applications like bone graft substitution and drug delivery. In this work, isopropyl alcohol has been used as a solvent to obtain low dimensional calcium sulfate dihydrate crystals from calcium nitrate - sulfuric acid system. Reactants in 0.5 molar concentration at ambient conditions generated uniform rod-shaped crystals of length 3–5 µm. Analysis using X-ray Diffractometry and Fourier Transform Infrared Spectrometry showed the material to be well crystallized, phase-pure calcium sulfate dihydrate. The nucleation kinetics has been studied by observing the induction time of phase formation in solutions of millimolar concentrations through turbidimetry at 300 K. The data have been analysed using classical nucleation theory to deduce parameters like interfacial tension (or surface free energy), nucleation rate and critical radius. The surface free energy obtained (5.6 mJ/m2) is comparatively lower than that reported for aqueous precipitation, which could be attributed to the presence of isopropyl alcohol. On escalating the supersaturation ratio, the nucleation rate drastically increased and the critical radius decreased exponentially. Particles formed at supersaturation 1.39 showed a monomodal distribution centered at 8.2 nm in Dynamic Light Scattering analysis. Comparable particle sizes were obtained in Transmission Electron Microscopy.
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