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非稳定状态的Fickian扩散模型降低了薄膜被动采样中的扩散梯度的估计凝层扩散系数不确定性

Samuel D Hodges¹, David G Wahman², Levi M Haupert²

¹Department of Civil Engineering, University of Arkansas, Fayetteville, Arkansas 72701, United States.

Environmental science & technology

|June 21, 2023

概括

一个新的有限差异模型 (FDM) 在被动样本中提高了凝扩散系数 (D_Gel) 的准确性. 这种先进的方法与标准分析相比,减少了不确定性的十倍,提高了大规模运输测量.

科学领域:

环境科学环境科学
分析化学分析化学
化学工程是化学工程的重要组成部分.

背景情况:

薄膜被动采样器中的质量传输依赖于通过凝层 (agarose或APA) 的扩散.
凝层扩散系数 (D_Gel) 对采样器性能至关重要.
使用Fick第一定律的标准分析 (SA) 通常假定伪稳定状态流量,限制准确性.

研究的目的:

开发和验证一种更准确的方法来确定凝层扩散系数 (D_Gel).
评估D细胞试验中标准分析 (SA) 的局限性.
实施一个有限差异模型 (FDM),以计算非平稳状态 (N-SS) 流量.

主要方法:

使用酸盐进行了72次双隔膜扩散细胞 (D细胞) 试验.
基于Fick的第一定律和回归模型的应用标准分析 (SA).
开发并使用基于Fick第二定律的有限差异模型 (FDM),结合N-SS流量.

主要成果:

SA确定了D_Gel具有显著的变异性 (例如,10.115.8 × 10−6 cm2·s−1对于阿加罗斯).
使用SA的回归模型显示D_Gel的95%置信区间很宽 (例如,在500rpm时为agarose的1318 × 10−6cm2·s−1).
FDM将D_Gel的不确定性降低了十倍,产生了精确的值 (例如,14.5 ± 0.2 × 10−6 cm2·s−1对于500rpm的阿加罗斯).

结论:

有限差异模型 (FDM) 在被动样本中显著提高了D_Gel测定的准确性.
在FDM中,度和流量的动态变化,克服了SA的局限性.
这种改进的方法为环境监测提供了更可靠的大众运输数据.

关键词:

扩散性边界层是一种扩散性边界层.环境采样环境采样实验方法实验方法这种水凝是水凝.

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