Knowing how wall shear stress develops at the membrane surface is extremely useful when trying to reduce concentration polarization and fouling. Newly developed as well as manufactured ceramic membranes exhibit various channel geometries (cylindrical, square, triangular, etc). Mass transport characteristics depend on the geometry that conditions hydrodynamic conditions. The goal of this work is to study the influence of the channel geometry on the wall shear stress for various operating parameters (tangential velocity, transmembrane pressure…). Numerical simulations are performed for various inlet velocities for different channel geometries. The wall shear stress along the channel perimeter as a function of the shape and the cross section of the channel are studied. The influence of the geometry on the membrane performances is also studied. The simulated shear stress is employed to correlate experimental results. The results of this comparison show that mass transfer resistance depends on the wall shear stress alone, regardless of the flow rate, the shape or section of the channels.

Solvents purification mainly used in pharmaceutical field such as acetone and methyl ethyl ketone (MEK) were performed through hybrid silica membranes and from binary and multi-components mixtures. Two hybrid silica membranes—zirconia doped bis(triethoxysilyl)methane and bis(triethoxysilyl)ethane (BTESE)—were studied. Flux, permeance, and separation factor were evaluated depending on temperature, composition, and number of organic compounds in the feed. Dehydration tests of acetone were operated at 30 and 45 °C following by acetone and MEK purification at 50 °C from multi-components hydro-organic mixtures where hydrophilic compounds (water, methanol) but also hydrophobic (dichloromethane (DCM) and/or toluene) were present. Results showed that the presence of Zr nanoparticles affected flux and improved selectivity in the case of dehydration. Experiments related to acetone and MEK purification, revealed a mass transfer alteration and a decrease of performance, from 99 to 97 wt% and from 98 to 95 wt% respectively, when the number of compounds in the initial feed grown up and more precisely, in the presence of DCM and toluene thus highlighting a possible coupling effect.

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Membrane processes have been intensely developing during the last decades, and mainly in dairy industry. Considering the feed effluent complexity, concentration polarization phenomenon and fouling are accentuated limitations for the development of membrane dairy filtration processes. Knowledge of the wall shear stress developed at the membrane surface is fundamental to reduce those phenomena. In this work, the variation of the wall shear stress on cylindrical, square, triangular and hybrid channels by numerical simulation for various operating parameters was studied. Predictions were established for different commercial ceramic membranes and predict the geometry that tends to better mass transport efficiency by enhancing hydrodynamics conditions. Numerical simulations are performed over a typical range of Reynolds numbers inside different channel geometries under laminar and turbulent conditions. Consequently, this paper intended to enhance the performances of these processes by maximizing the average wall shear stress on the membrane surface by numerical simulation. A comparison with experimental results was realized and a good agreement was obtained. Given those conclusions, a new membrane according to the whole CFD results consistent with experimental results was designed.

The development of chemical reactions catalysed by homogeneous organometallic complexes has allowed a significant breakthrough in synthesis chemistry, but now research axes must integrate catalysts recycling at the early stage of their conception. Catalyst recycling by nanofiltration in organic solvent (OSN) may represent an innovative route since this separation process at a molecular level is a low energy consumer. Challenges for OSN are membrane stability in organic solvents and the mastering of filtration conditions. Molecular engineering of catalysts based on slight structural modifications is also proposed to associate activity and high retention for OSN recycling. This paper deals with the integration of OSN within the homogeneous catalytic olefin metathesis reaction.