Abstract Membrane-based filtration is an emerging technique for processing oily wastewater. Improving the efficiency of oil-water separation via membranes entails novel techniques for studying the complex interactions between the oil droplets and membrane underlying fouling. This paper presents the first study that applies optical coherence tomography (OCT) to the characterization of membrane fouling by oil emulsions. A series of dead-end filtration experiments was performed to characterize the rejection of oil droplets (~ 10 µm; hexadecane) by the membrane structure (0.45 µm PVDF) via three-dimensional (3D) OCT scanning in real time. The experimental results were compared with the control experiments with ~ 10 µm glass beads to identify the optical artifacts. Both the external and internal fouling by the oil droplets were successfully revealed by analyzing the variation in OCT intensity at various layers that were mathematically defined in terms of the coordinate surfaces parallel to, and above and below, the feed-membrane interface. The evolution of membrane fouling was quantified by evaluating the fraction of fouling voxels as a function of time at varied depths. This study demonstrates that the OCT-based characterization has the potential to shed light on the complex interactions occurring in oil-water separations via membrane filtration, particularly by providing real-time non-invasive monitoring of internal fouling, the understanding of which is valuable for both fundamental research and practical applications.

中文翻译：

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通过 3D 光学相干断层扫描分析油乳液造成的内外膜污染

摘要 膜过滤是一种新兴的含油废水处理技术。通过膜提高油水分离的效率需要新技术来研究油滴和膜之间的复杂相互作用。本文介绍了第一项将光学相干断层扫描 (OCT) 应用于油乳液对膜污染的表征的研究。进行了一系列死端过滤实验，以通过实时三维 (3D) OCT 扫描来表征膜结构 (0.45 µm PVDF) 对油滴 (~ 10 µm；十六烷) 的排斥。将实验结果与使用 ~ 10 µm 玻璃珠的对照实验进行比较，以识别光学伪影。通过分析不同层的 OCT 强度的变化，成功地揭示了油滴的外部和内部污垢，这些层是根据平行于进料膜界面、上方和下方的坐标表面进行数学定义的。通过在不同深度评估作为时间函数的污垢体素的分数来量化膜污垢的演变。这项研究表明，基于 OCT 的表征有可能揭示通过膜过滤进行油水分离中发生的复杂相互作用，特别是通过提供对内部污垢的实时非侵入性监测，了解这一点对于无论是基础研究还是实际应用。