Dense Membrane Crystallization in Gas–Liquid Systems: Key Parameters Influencing Fouling

Maïté Michaud (1) , Denis Mangin (1) , Catherine Charcosset (1) , Elodie Chabanon (1)

1 LAGEPP - Laboratoire d'automatique, de génie des procédés et de génie pharmaceutique

Membranes have been increasingly considered as a promising technology to conventional crystallization processes. One of the most significant benefits would be to control the supersaturation by fine-tuning the mass transfer throughout the membrane. Several investigations on this topic have already been proposed using porous materials. However, numerous authors dealt with scaling phenomena with either pore blocking or surface fouling. To reduce this issue, the use of dense skin membranes seems to be an interesting alternative while keeping other membrane advantages. The present study aims at analyzing the potential of nonporous materials in membrane contactors used for crystallization purposes. More specifically, two major scientific challenges are investigated closely: how to avoid membrane fouling by choosing appropriate membrane materials and to predict, potentially, the crystallization location in/on a dense polymeric material. The global aim of this study is to better understand the fouling mechanisms in dense membranes. Several commercially available materials are screened and experiments are conducted under a strict diffusion regime in a gas−liquid system with a stagnant liquid phase at 20°C. Impact of no-hydrodynamics parameters on the crystallization location is studied, namely, changes in gas flowrate, membrane thickness, polymer type, physical state, and initial moisture. It is shown that the first major key parameter to be considered to prevent fouling is the surface energy of the material. The results obtained highlight that hydrophilic membranes such as cellulose acetate are much more difficult to clean than hydrophobic membranes, such as fluorinated ethylene propylene (FEP). This material property will impact the adherence of a solid compound on the membrane. The permeability of all chemical reactants and their interaction with the membrane materials are the second key parameter to investigate carefully. The results obtained show that no crystals are present on the surface of hydrophobic and highly permeable polymers, such as polydimethylsiloxane (PDMS) or Teflon AF 2400; meanwhile, large amounts of crystals are recovered in the solution. On the contrary, crystals are dropped off the membrane surface of hydrophobic but less permeable polymers like FEP, although the amount of crystals recovered in the solution compartment is at least 10 times lower by using FEP than PDMS or Teflon AF 2400. These two parameters have a crucial incidence on the solid deposit location in/on the membrane. In the context of this study, membrane fouling is expected to be avoided by using appropriate hydrophobic and highly permeable dense membranes such as Teflon AF 2400 and PDMS.

Domaines: Sciences du Vivant [q-bio]; Sciences pharmaceutiques; Sciences de l'ingénieur [physics]; Génie des procédés; Génie chimique

Maïté Michaud, Denis Mangin, Catherine Charcosset, Elodie Chabanon. Dense Membrane Crystallization in Gas–Liquid Systems: Key Parameters Influencing Fouling. Industrial and engineering chemistry research, 2019, 58 (43), pp.20134-20146. ⟨10.1021/acs.iecr.9b03907⟩. ⟨hal-03033909⟩