Online fouling monitoring

The possible tools today to make this come true are cleaning the membrane and running the process at constant flux and, in order to avoid fouling, running at a subcritical flux [4]. To find the best long-term conditions some online monitoring is needed. It has been noticed that in many discussions with industry one of the most important items on their wish list is to monitor the membrane process and characterize the membrane, possibly on-/inline. 

Confocal Scanning Laser Microscopy Fundamentals and Uses on Membrane Fouling Characterization and Opportunities for Online Monitoring... 

Additionally, online monitoring methods have been developed to adapt off-line characterization methods into in situ (i.e., in-reactor) probes for determination of kinetics and monomer conversion with optical methods such as mass spectroscopy (MS), ESR, FTIR, near IR, and Raman spectroscopy. However, frequently, due to high turbidity and viscosity of the polymer reaction milieu, the optical surfaces are easily fouled, leading to frequent sensor failure. Furthermore, data acquired with these probes are model dependent the empirical and inferential calibration schemes used can be expensive and time consuming to develop and can drift and become unreliable as reactor conditions change and as sensors become fouled. Another limiting feature of these methods is that they usually measure only one characteristic of the reaction, such as monomer conversion and are not directly sensitive to polymer molecular mass and intrinsic viscosity. More detailed discussion of these techniques can be found in Chapters 6-10 of this book. 

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