Characterization of particle deposition during crossflow filtration as influenced by permeate flux and crossflow velocit
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RESEARCH ARTICLE
Characterization of particle deposition during crossflow filtration as influenced by permeate flux and crossflow velocity using a microfluidic filtration system Hongzhan Di, Gregory J. O. Martin, Dave E. Dunstan (✉) Department of Chemical and Biomolecular Engineering, University of Melbourne, Parkville, Victoria 3010, Australia
© Higher Education Press 2020
Abstract Particle deposition during crossflow filtration is significantly influenced by the operating conditions, in particular the permeate flux and crossflow velocity. However, there is a lack of detailed knowledge about how deposit layer structures and distributions depend on operating parameters. This study uses a microfluidic visualisation filtration system to examine the influence of operating conditions on the deposition process during crossflow ultrafiltration from a microscopic perspective. Increasing the permeate flux caused an increasing amount of deposition and a thicker deposit layer. Higher crossflow velocities reduced the extent of deposition. The degree of deposition varied over a range of operating conditions due to the altered hydrodynamic forces exerted on the particles, which can be examined by the deposition probability according to an existing model. Building on this, an empirical correlation between the deposition probability and volume of deposition as a function of filtration time was developed, which gave good agreement with experimental results. The effect of solution conditions was also involved in this correlation as a interaction energies. This could be useful for predicting the dynamic deposition process during crossflow filtration over a range of operating and solution conditions. Keywords particle deposition, crossflow filtration, microfluidics, confocal microscopy
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Introduction
Membrane filtration as a separation process has been playing an important role in many industries [1–5]. Received March 24, 2020; accepted May 21, 2020 E-mail: [email protected]
However, the particle deposition that occurs during filtration causing membrane fouling significantly reduces the separation efficiency and requires extra energy to maintain the separation performance [6–8]. It has been found that membrane fouling is significantly affected by solution conditions such as pH, ionic strength [9–11] and membrane properties [12–15], as well as operating conditions such as permeate flux and crossflow velocity [16–18]. Solution conditions affect the deposition process by mainly varying the electrostatic interactions (particle– particle and particle–membrane), while operating conditions have a strong bearing on the degree of particle deposition by varying the hydrodynamic forces acting on particles. A number of studies have indirectly investigated how variable conditions affect the deposition process during membrane filtration by monitoring macro parameters such as deposit layer thickness [19–21] and permeate flux [22– 24]. However, these macro measurements are limited in interpreting the detailed mechanism of the fouling process. In addition, traditional theo
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