Emerging investigators series: a steric pore-flow model to predict the transport of small and uncharged solutes through a reverse osmosis membrane
Emerging investigators series: a steric pore-flow model to predict the transport of small and uncharged solutes through a reverse osmosis membrane
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新兴研究人员系列：空间孔隙流模型，用于预测小且不带电荷的溶质通过反渗透膜的运输
DOI：
10.1039/c7ew00194k
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Fujioka Takahiro
中科院分区：
文献类型：
--
作者：
Takeuchi Haruka;Tanaka Hiroaki;Nghiem Long D.;Fujioka Takahiro
本研究提出了一种新的方法，应用空间孔流模型来预测通过反渗透膜在饮用水回用中非常关注的八种N-亚硝胺和七种挥发性有机化合物的截留率。在这种方法中，溶质排斥预测通过估计的自由体积孔的大小。自由体积孔半径由膜的纯水渗透率和单一参比化合物-N-亚硝基二甲胺（NDMA）-通过在20 L m−2 h−1的渗透通量下最小化实验获得的和计算的NDMA截留值之间的方差来确定。所得到的ESPA 2 RO膜的自由体积空穴半径为0.348 nm，其大于先前通过正电子湮没寿命谱（帕尔斯）分析确定的值（0.289 nm）。结合估算的自由体积孔半径的模型可以准确地预测在一定的渗透通量范围内（2.6-20 L m−2 h−1）的八个N-亚硝胺的排斥。该模型也验证了实验获得的VOC拒绝值。在渗透通量为20 L m−2 h−1时预测的VOC截留率与实验获得的截留率几乎相同。然而，在较低的渗透通量下的VOC截留预测不太准确。需要用各种痕量有机化学品进一步改进和验证模型，以实现更准确的预测。该模型还验证了使用膜自由体积孔半径值先前获得的帕尔斯分析。使用帕尔斯数据会导致一些过度预测。结果表明，额外的调整是必要的，当使用数据从帕尔斯分析预测小和不带电的溶质的排斥。
This study proposed a new approach to apply the steric pore-flow model to predict the rejection of eight N-nitrosamines and seven VOCs that are of great concern in potable water reuse through an RO membrane. In this approach, solute rejection is predicted by estimating the free-volume hole-size. The free-volume hole-radius was determined with pure water permeability of a membrane and a single reference compound – N-nitrosodimethylamine (NDMA) – by minimizing the variance between the experimentally obtained and calculated NDMA rejection values at the permeate flux of 20 L m−2 h−1. The obtained free-volume hole-radius of the ESPA2 RO membrane was 0.348 nm, which was larger than the value previously determined by positron annihilation lifetime spectroscopy (PALS) analysis (0.289 nm). The model incorporated with the estimated free-volume hole-radius could accurately predict the rejection of eight N-nitrosamines under a range of permeate flux (2.6–20 L m−2 h−1). The model was also validated using experimentally obtained VOC rejection values. The predicted VOC rejections at the permeate flux of 20 L m−2 h−1 were almost identical to their experimentally obtained rejections. However, VOC rejection prediction at a lower permeate flux was less accurate. Further improvement and validation of the model with a variety of trace organic chemicals is required to allow for a more accurate prediction. The model was also validated using the membrane free-volume hole-radius value previously obtained from PALS analysis. Using PALS data resulted in some over-prediction. The results suggest that additional adjustment is necessary when using data from PALS analysis for predicting the rejection of small and uncharged solutes.