Membrane
Ahmed Fadhil Jumaah; Reza Abedini
Abstract
Propylene is a widely used compound in various industrial applications, but its separation from propane, which is often associated with it, remains a significant challenge. Among the separation methods, membrane technology, particularly polymeric membranes, offers an attractive solution due to its relatively ...
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Propylene is a widely used compound in various industrial applications, but its separation from propane, which is often associated with it, remains a significant challenge. Among the separation methods, membrane technology, particularly polymeric membranes, offers an attractive solution due to its relatively low cos t and simplicity. In this study, hydroxyl-functionalized graphene (G─OH) nanosheets were used as an additive in a Pebax 1657 matrix. The results from Fourier Transform Infrared Spectroscopy (FTIR) revealed that the interaction between Pebax and G─OH is physical, characterized by a shift in some peaks due to hydrogen bonding. The proper dispersion of G─OH in the Pebax matrix was confirmed by Differential Scanning Calorimetry (DSC), which also showed an increase in the glass transition temperature (Tg), indicating the rigidity of Pebax chains in the presence of G─OH. Thermogravimetric Analysis (TGA) results demonstrated that the degradation temperatures (Td) of Pebax/ G─OH 1 wt.% and Pebax/G─OH 2 wt.% membranes were 335°C and 330°C, respectively. A comprehensive gas permeation study, including pure and mixed gas tests at feed pressures of 2, 6, and 10 bar, as well as a long-term stability test, was conducted on the membranes. Among all the MMMs, Pebax/G─OH 1.5 wt.% demonstrated the best gas separation performance, achieving a propylene permeability of 89.8 barrer and a C3H6/C3H8 selectivity of 9.8. Additionally, under mixed gas permeation tests (50:50 v/v of C3H6 and C3H8), this membrane exhibited a propylene permeability of 76.3 barrer and a C3H6/C3H8 selectivity of 8.8. Finally, the performance of the MMMs in C3H6/C3H8 separation was benchmarked against the Robeson upper bound curve.
Membrane
Nazila Sutudehnezhad; Amir Heydarinasab; Reza Yegani; Farshid Pajoum Shariati
Abstract
Membrane bioreactors (MBRs) are high-tech systems for water recycling and reusing of unconventional water resources such as municipal wastewater. However, the fouling of polymeric membranes is the main impediment to the market development of MBR. The polyolefin-based membranes are subjected to more severe ...
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Membrane bioreactors (MBRs) are high-tech systems for water recycling and reusing of unconventional water resources such as municipal wastewater. However, the fouling of polymeric membranes is the main impediment to the market development of MBR. The polyolefin-based membranes are subjected to more severe organic fouling than other hydrophilic membranes due to their inherent strong hydrophobic properties, therefore, proposing efficient, fast, and economic fouling mitigation methods is vital for durable and long-standing performance. In this research, the hydrodynamics of a lab-scale membrane bioreactor with different configurations of aerators and nozzle sizes were used to investigate the air scouring efficiency. It was gained that aerators with higher air flow rates, e.g., 5.5 m/s can produce slug bubbles which are capable of foulant removal from the membrane surface. In comparison with a non-central aerator, the satisfactory scouring zone of the central aerator is narrow and the edge nozzles on both sides of the aerator are blocked. Under constant air flow rate, when the inlet air is injected into the aerator from two and three points, not only the end nozzles are blocked but also the liquid is penetrated into the aerator and the shear stress on the membrane surface decreased to 0.765 Pa. In the case of the non-central aerator, the satisfactory scouring zone becomes wider and neither nozzle blockage nor liquid penetration down to the aerator has occurred. The distribution of bubbles was optically evaluated by video imaging through the transparent plexiglass tank using aerators with different inlet flow rates and various configurations. Numerical simulations and related experimental analyses demonstrated that air inlet velocity has an important role in creating larger slug bubbles. It was shown that a non-central aerator in which the central nozzle in front of the inlet air stream is blocked, produces slug bubbles and sufficient air scoring on the flat sheet membrane. Configuration of a non-central aerator with 4 nozzles not only increased the satisfactory zone of each aerator without blockage of edge nozzles and liquid penetration into the aerator but also provided a higher shear rate over 1.104 Pa under a constant flow rate, which consequently removed the foulant from the membrane surface.
Membrane
Saba Raveshiyan; Parya Amirabedi; Reza Yegani; Behzad Pourabbas; Akram Tavakoli
Abstract
Wetting of polymeric hollow fiber membranes by chemical absorbents is one of the main challenges of gasliquid membrane contactors. This study explored an appropriate method to fabricate a superhydrophobic polypropylene (PP) hollow fiber membrane by incorporating fluorinated silica nanoparticles (fSiO2 ...
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Wetting of polymeric hollow fiber membranes by chemical absorbents is one of the main challenges of gasliquid membrane contactors. This study explored an appropriate method to fabricate a superhydrophobic polypropylene (PP) hollow fiber membrane by incorporating fluorinated silica nanoparticles (fSiO2 NPs) on the PP membrane surface. The effect of the hydrophobic agent on the water repellent properties of the composite membrane was studied by varying (1H,1H,2H,2H-perfluorooctyltriethoxysilane/ tetraethylorthosilicate) (PFOTES/TEOS) molar ratio from 0 to 1. The composite membranes were characterized using field emission scanning electron microscopy (FESEM), attenuated total reflection-Fourier transform infrared (ATR-FTIR), contact angle, mechanical strength and static wettability. The obtained results showed that the surface hydrophobicity and mechanical strength of the composite membranes increased compared to pure ones. The contact angle of 156° was obtained when the (PFOTES/ TEOS) molar ratio was 0.5. Furthermore, the CO2 absorption experiment was done to evaluate the performance of the fabricated membranes in a gas-liquid membrane contactor. The obtained results showed that the PP/fSiO2 composite membrane has more potential to be used in gas-liquid membrane contactors than commonly used polymeric membranes
