Chemical transport in silicone rubber membranes from pure powders and saturated aqueous solutions
Chemical transport in silicone rubber membranes from pure powders and saturated aqueous solutions
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DOI：
10.1016/j.memsci.2007.01.007
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发表时间：
2007-04-05
影响因子：
9.5
通讯作者：
Bunge, Annette L.
中科院分区：
文献类型：
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作者：
Ley, Eugene E.;Bunge, Annette L.
在这项研究中，膜的渗透是通过硅橡胶（聚二甲基硅氧烷）使用扩散池操作，以确保在膜和受体溶液之间的界面上的浓度可以忽略不计，从精细划分的纯粉末和两种低蒸汽压测试化学品（对羟基苯甲酸甲酯和4-氰酚）的饱和水溶液中测量的。纯粉末的稳态通量很大，与饱和水溶液的通量相似，但比饱和水溶液的通量小，这在统计上是显著的。然而，NIP和CP的纯粉和饱和水的通量比没有统计学差异（分别为0.66 +/- 0.10和0.72 +/- 0.07），这表明粉末和饱和水的通量结果不同是由物理原因而不是化学原因造成的。一种解释是，对于饱和溶液，扩散是从整个膜表面进行的，但对于这些几乎不挥发的化学物质，扩散只从与纯粉末直接接触的膜表面进行。与这些新结果相反，早期的一项研究发现，安装在衰减全反射傅立叶变换红外（ATR-FTIR）晶体上的硅橡胶膜对3-和4-氰酚的吸收速率和吸收量没有差异。在扩散池和ATR-FTIR实验系统中，仅覆盖一小部分膜表面的非挥发性化学源的数学模型模拟结果表明，测量变异性足够大，使得早期的研究对粉末和饱和溶液的差异不敏感。从数学模型模拟与新扩散池结果的比较中，我们估计在粉末实验中，只有不到5%的膜表面与化学物质直接接触。(c) 2007 Elsevier B.V.版权所有
In this study membrane permeation was measured from finely divided pure powder and saturated aqueous solutions of two test chemicals with low vapor pressure, methyl paraben and 4-cyanophenol, through silicone rubber (polydimethylsiloxane) using diffusion cells operated to insure the concentration was negligible at the interface between the membrane and the receptor solution. The steady-state flux from the pure powder was substantial and similar to that from a saturated aqueous solution, but smaller by an amount that was statistically significant. However, there was no statistically significant difference in the ratios of the fluxes from the pure powder and saturated water for NIP and CP (0.66 +/- 0.10 and 0.72 +/- 0.07, respectively), suggesting a physical rather than chemical cause for the different flux results for powder and saturated water. One explanation is that diffusion proceeds from the entire membrane surface for the saturated solution, but only from the membrane surface in direct contact with the pure powder for these nearly non-volatile chemicals. In contrast to these new results, an earlier study saw no difference in the rate or amount of absorption of 3- and 4-cyenophenol into silicone rubber membranes mounted on an attenuated total reflectance Fourier transform infrared (ATR-FTIR) crystal. The results from mathematical model simulations of non-volatile chemical sources covering only a fraction of the membrane surface in the diffusion cell and ATR-FTIR experimental systems suggest that the measurement variability was large enough to make the earlier study insensitive to differences in the powder and saturated solutions. From a comparison of the mathematical model simulations to the new diffusion cell results, we estimate that less than 5% of the membrane surface had direct contact with chemical in the powder experiments. (c) 2007 Elsevier B.V. All rights reserved.