Real-time monitoring of calcium sulfate scale removal from RO desalination membranes using Raman spectroscopy
Real-time monitoring of calcium sulfate scale removal from RO desalination membranes using Raman spectroscopy
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DOI：
10.1016/j.desal.2020.114736
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发表时间：
2021-01-01
期刊：
影响因子：
9.9
通讯作者：
Bright, Victor M.
中科院分区：
文献类型：
--
作者：
Park, Danielle J.;Supekar, Omkar D.;Bright, Victor M.
通过拉曼光谱在小型反渗透 (RO) 系统中实时进行结垢和去除过程的化学表征。定制的 RO 错流池与拉曼显微镜物镜集成，可以分析局部膜结垢和除垢。还测量了渗透通量以提供用于比较的实时指标。使用硫酸钙（CaSO4 中心点 H2O）进料溶液对商用平板薄膜复合反渗透 (TFC RO) 膜进行结垢。检测到 CaSO4 水垢后，将进料切换为去离子水，用作清洁剂以去除膜上的 CaSO4 水垢。除了实时局部（拉曼）和全局（渗透通量）测量之外，还使用拉曼光谱、重量分析和扫描电子显微镜对膜样品进行事后表征，以提供重要的结垢和除垢指标。实时测量结果表明，拉曼强度的变化是比渗透通量的变化（标准清洁性能指标）更敏感的局部水垢去除指标；尸检分析证实了这些发现。总体而言，膜清洗实验表明拉曼光谱提供了关键的实时化学成分和空间分布信息，可以为更有效的防垢和清洗策略提供信息。
Chemical characterization of scaling and removal processes was performed in real time via Raman spectroscopy in a bench-scale reverse osmosis (RO) system. A custom RO cross-flow cell was integrated with a Raman microscope objective, allowing for analysis of localized membrane scaling and scale removal. Permeate flux was also measured to provide a real-time metric for comparison. A commercial flat sheet, thin-film composite reverse osmosis (TFC RO) membrane was scaled using a calcium sulfate (CaSO4 center dot H2O) feed solution. Upon CaSO4 scale detection, the feed was switched to DI water, which served as a cleaning agent to remove the CaSO4 scale from the membrane. In addition to the real-time local (Raman) and global (permeate flux) measurements, membrane samples were characterized post-mortem using Raman spectroscopy, gravimetric analysis and scanning electron microscopy to provide important scaling and scale removal metrics. Results from real-time measurements indicated that changes in Raman intensity were a more sensitive indicator of local scale removal than changes in permeate flux, a standard cleaning performance metric; these findings were corroborated by the post-mortem analyses. Overall, the membrane cleaning experiments showed that Raman spectroscopy provided crucial real-time chemical composition and spatial distribution information, which can inform more effective antiscaling and cleaning strategies.