Effect of crystallization kinetics on the properties of spray dried microparticles
Effect of crystallization kinetics on the properties of spray dried microparticles
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DOI：
10.1080/02786826.2016.1177163
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发表时间：
2016-01-01
影响因子：
5.2
通讯作者：
Vehring, Reinhard
中科院分区：
文献类型：
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作者：
Baldelli, Alberto;Power, Rory M.;Vehring, Reinhard
采用液滴链技术研究了结晶过程对喷雾干燥微粒形貌的影响。压电陶瓷分配器产生初始直径在60-80 mm范围内的单分散溶液液滴链。制备浓度在5 mg/ml至5.10（-5）mg/ml范围内的硝酸钠水溶液。将溶液液滴注入气体温度在25至150摄氏度之间变化的层流中，从而影响液滴温度和蒸发速率。收集直径在0.3和18 μ m之间的干燥颗粒。收集的微粒的性质进行了研究，并与预测饱和和结晶的发病的颗粒形成模型。该模型考虑了硝酸钠在水中的扩散系数对液滴粘度的依赖性。通过研究在光镊中悬浮的两个硝酸钠水溶液液滴的聚结过程中观察到的弛豫时间来确定硝酸钠溶液的粘度趋势。理论推导和实验结果的结合表明，较长的结晶时间与最终微粒中较大的晶体尺寸和较高的结晶度相关。
A droplet chain technique was used to study the influence of the crystallization process on the morphology of spray dried microparticles. A piezoceramic dispenser produced a chain of monodisperse solution droplets with an initial diameter in the range of 60-80 mm. Aqueous solutions of sodium nitrate were prepared in concentrations ranging from 5 mg/ml to 5.10(-5) mg/ml. The solution droplets were injected into a laminar flow with gas temperatures varying from 25 to 150 degrees C, affecting the droplet temperature and the evaporation rate, accordingly. Dried particles with diameters between 0.3 and 18 mu m were collected. The properties of the collected microparticles were studied and correlated with a particle formation model which predicted the onset of saturation and crystallization. The model accounted for the dependence of the diffusion coefficient of sodium nitrate in water on droplet viscosity. The viscosity trend for sodium nitrate solutions was determined by studying the relaxation time observed during coalescence of two aqueous sodium nitrate droplets levitated in optical tweezers. The combination of theoretical derivations and experimental results showed that longer time available for crystallization correlates with larger crystal size and higher degrees of crystallinity in the final microparticles.