Whey, as a strong environmental pollutant, is produced along the production of cheese and contains about 50% of the valuable nutrients of milk. The membrane-based separation process is one of the most fascinating technologies for concentration and purification of whey proteins in the dairy industries; using this technology makes fewer damages to the nutrients of whey. In addition, separation of the valuable compounds of whey makes less environmental problems. In this study, three different Nanostructure PES hollow fiber membranes with different characterization and pore sizes have been used and their intrinsic resistances were measured; the effect of temperature and pressure on fouling resistances and the effect of temperature on the permeation flux, protein rejection, and lactose permeation were studied. The results showed that permeation flux increases with increase in temperature. The intrinsic resistance and fouling resistances of the membranes increase with a decrease in pore size. The fouling resistance increases by pressure even though the intrinsic resistance of the membrane doesn't change.

membranes are the main component in blood purification processes such as hemodialysis, responsible for removing metabolic waste products like urea. Pure polymer-based membranes often suffer from drawbacks such as hydrophobicity and poor biocompatibility. Therefore, this study aims to improve the surface properties of polyethersulfone (PES) membranes by incorporating activated carbon particles. hollow fiber membranes were fabricated using the phase inversion method via non-solvent induced phase separation. The surface characteristics of pure PES membranes and those containing 0. 3 wt% activated carbon particles were investigated and compared. The pure PES membrane was characterized in terms of morphology and pure water permeability (PWP), which was measured at 29 L·m–2·h–1·bar–1. A decrease in water contact angle from 54° to 40° in the composite membrane indicated enhanced surface hydrophilicity, positively affecting membrane performance. Additionally, the surface roughness of the composite membrane increased compared to the pure sample (from 7. 00 nm to 7. 83 nm). Thus, the incorporation of activated carbon particles enhanced the hydrophilicity of PES hollow fiber membranes, consequently improving their performance for hemodialysis applications.

Background and Objective: Whey is a by-product of dairy industries along cheese production. As a raw material, whey has several applications in food industries and its valuable protein and lactose contents. membrane technology, more specifically ultrafiltration (UF), is being used in dairy industry to produce whey protein concentrate (WPC) because this technology allows selective separation of whey proteins compared to the rest of its components. In this regard, the objective of this research was to investigate the effects of different operating parameter on whey protein concentration and purification process using ultrafiltration membranes. Method: Three different Nanostructure Poly-Eether-Sulfone (PES) hollow fiber membranes were tested and the effects of operating parameters, temperature (43 oC), three different pressures (1 bar, 2 bar, 3 bar) and feed flow rate on the permeate flow rate, protein rejection and lactose permeation were studied. Findings: Results showed that pressure increase enhances the permeation flow rate which is more sensible at lower pressures. Moreover, high pressures have not been considered suitable considering higher fouling and lower flux recovery. Increasing feed flow rate resulted in higher turbulence on the surface of the membrane and reduces the membrane fouling and enhances the permeation flow rate even though these parameters (pressure and feed flow rate) did not have any significant effect on the protein rejection and lactose permeation. At the best operating conditions, maximum protein rejection was %91. 01. Discussion and Conclusion: considering the findings, it can be concluded that UF process using PES hollow fiber membrane is capable of performing desired separation and purification of whey.

In this paper, a system for efficient removal of carbon dioxide by hollow fiber membranes is proposed. The system is compact, and it is very useful for application in the offshore energy industries. In particular, it is used to removing CO2 from the exhaust of power generation facilities on offshore platforms. The proposed dual membrane contactor contains two types of membranes (polypropylene membrane and silicone rubber membrane); moreover, the dual membrane contactor was designed and constructed for gas absorption processes. The module performance was evaluated based on permeation flux experiments. The experimental results were compared with the predictions from a numerical model developed in our previous studies. Furthermore, the mass transfer resistance in the fabricated module was investigated using resistance-in-series model. It is proposed that the computational techniques be used to develop design techniques in these kinds of complex systems. In addition, experimental methodologies have been used for the design and optimization of cross-flow hollow fiber membrane modules to absorb or desorb the gas. However, the experiments can be expensive and time consuming. Numerical simulations used in conjunction with experiments can decrease the number of required experiments, thus reduce the required costs and time. In this work, a new modelling approach using computational fluid dynamics (CFD) is proposed to improve modelling flow within cross-flow membrane modules, and subsequently as a design means for such modules. In the CFD model, the fiber bundle is modeled as a porous medium to capture flow characteristics through the fiber bundle. Also, mass transfer equations in the fiber and shell sides are coupled and solved using an iteration algorithm by taking consideration of the influence of flow behavior of both gas phase and liquid phase. In parallel, experimental study was also carried out to validate the results of computational modeling. The CFD modeling results correlated well with the experimental data obtained from a lab scale cross-flow membrane module with uniform distributed fibers. The developed model was then used to examine the performance of modules with more complex geometries such as baffled modules and modules containing unevenly distributed fiber bundles. Finally, it was demonstrated that the CFD simulation is a promising approach in developing and optimizing cross-flow membrane module.

Hypothesis: Dehumidification of a gas stream was carried out by one of the newest separation techniques. Different processes have been proposed for gas humidification such as absorption process using an absorbent and adsorption process with higher capital and operating costs than the former. The former process is more common. Methods: For humidification/dehumidification process two hollow fiber membrane contactor modules were made using polyetherimide hollow fiber membranes. At first, the dry inlet gas was humidified in the first contactor module and then, the dehumidification process was performed by the second module. In dehumidification process, monoethylene glycol (as the absorbent) was allowed to flow through the shell side of the contactor while the wet gas flowed through the fibers. The different operating parameters such as the pressure and flow rate of the wet gas were studied in relation to the performance of dehumidification system. Findings: The results showed that by increasing the wet gas flow rate from 1 SLPM (standard liter per minute) to 3 SLPM, the water vapor absorption flux increased by 133%, indicating that the effect of decrease in gas phase mass transfer resistance in dehumidification process overcomes the effect of reduction in humidity content of the inlet gas to the dehumidification system. Furthermore, by increasing the gas pressure from 1 bar to 5 bar, the water vapor absorption flux decreased by 55% which showed that drop in humidity content of the inlet gas to dehumidification system (due to the pressure enhancement) affects the water vapor absorption process. Therefore, the operating conditions of the dehumidification process should be selected based on the effective parameters.

Polyacrylonitrile (PAN) hollow fiber membranes were manufactured through the dry-jet wet spinning. Considering importance effect of structure of hollow fiber to separation performance, spinning parameters such as coagulants composition were changed to achieve suitable hollow fiber membranes. Water with different amount of glycerin was used as the bore liquid and coagulation bath. The effects of the glycerin concentration on the hollow fiber permeation and separation performance were investigated. Direct red 80 was used to measure the separation performance of hollow fiber module. Field emission scanning electron microscope (FE-SEM) was used to analyze the structure of the hollow fibers. The results proved that permeation is increased by adding glycerin to external and internal coagulation bath. In addition, hollow fibers spun in lower glycerin value would indicate lower hydraulic permeability, higher separation and higher tensile strength.

Wetting of polymeric hollow fiber membranes by chemical absorbents is one of the main challenges of gasliquid membrane contactors. This s tudy 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 s tudied 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 s trength and s tatic wettability. The obtained results showed that the surface hydrophobicity and mechanical s trength 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.