Diffusion and Tortuosity in Porous Functionalized Calcium Carbonate

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• 作者：Charlotte L. Levy ; G. Peter Matthews ; Giuliano M. Laudone ; Christopher M. Gribble ; Andrew Turner ; Cathy J. Ridgway ; Daniel E. Gerard ; Joachim Schoelkopf ; Patrick A. C. Gane
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2015
• 出版时间：October 21, 2015
• 年：2015
• 卷：54
• 期：41
• 页码：9938-9947
• 全文大小：534K
• ISSN：1520-5045

文摘

Calcium carbonate can be 鈥渇unctionalized鈥?by use of etching agents such as phosphoric acid to create inter- and intraparticle porosity with a range of morphologies. Functionalized calcium carbonate has potential for use as a carrier for the delayed release of actives, such as drugs, plant protection chemicals, and food additives such as flavors. The drug or flavor is released slowly by permeation and diffusion. In order to measure the effective rate of diffusion within a range of morphologies, and hence gain insights into the optimum mode of functionalization, the diffusion of vanillin in ethanol is reported. Effective diffusion coefficients D鈥?were measured in a flow cell connected to a high performance liquid chromatograph (HPLC). Samples were also subjected to mercury intrusion porosimetry. The resulting percolation characteristics were inverse modeled using the PoreXpert package to generate representative void structures with estimated tortuosities. It is shown that the primary particle size of a sample was a better predictor of D鈥?calculated from the experimental diffusion curves, and also of the porosity-scaled tortuosity values, than the porosity or surface area. There was also a correlation between intraparticle tortuosity, scaled by porosity, and diffusion coefficient. The approach is validated by experimental evidence from this and related studies.