scholarly journals Understanding the Role of Pattern Geometry on Nanofiltration Threshold Flux

Membranes ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 445
Author(s):  
Anna Malakian ◽  
Zuo Zhou ◽  
Lucas Messick ◽  
Tara N. Spitzer ◽  
David A. Ladner ◽  
...  
Keyword(s):  
Membrane Surface ◽  
Cross Flow ◽  
Cake Filtration ◽  
Cross Flow Filtration ◽  
Colloidal Fouling ◽  
Computational Fluid Dynamics Simulations ◽  
Flow Filtration ◽  
Dynamics Simulations ◽  
The Relationship

Colloidal fouling can be mitigated by membrane surface patterning. This contribution identifies the effect of different pattern geometries on fouling behavior. Nanoscale line-and-groove patterns with different feature sizes were applied by thermal embossing on commercial nanofiltration membranes. Threshold flux values of as-received, pressed, and patterned membranes were determined using constant flux, cross-flow filtration experiments. A previously derived combined intermediate pore blocking and cake filtration model was applied to the experimental data to determine threshold flux values. The threshold fluxes of all patterned membranes were higher than the as-received and pressed membranes. The pattern fraction ratio (PFR), defined as the quotient of line width and groove width, was used to analyze the relationship between threshold flux and pattern geometry quantitatively. Experimental work combined with computational fluid dynamics simulations showed that increasing the PFR leads to higher threshold flux. As the PFR increases, the percentage of vortex-forming area within the pattern grooves increases, and vortex-induced shielding increases. This study suggests that the PFR should be higher than 1 to produce patterned membranes with maximal threshold flux values. Knowledge generated in this study can be applied to other feature types to design patterned membranes for improved control over colloidal fouling.

Ultrafiltration of Aqueous Solutions of Food Dye in the Presence of Surfactants

2017 ◽  
Vol 68 (1) ◽  
pp. 6-10
Author(s):  
George Alexandru Popa ◽  
Daniela Florentina Popa (Enache) ◽  
Dumitra Daniela Slave (Clej) ◽  
Ion Din Spiridon ◽  
Cristina Monica Mirea ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Membrane Surface ◽  
Cross Flow ◽  
Sodium Octanoate ◽  
Food Dye ◽  
Cross Flow Filtration ◽  
Dead End ◽  
Food Dyes ◽  
Flow Filtration ◽  
Quinoline Yellow

The objective of the study is the low-pressure membrane process for treating aqueous solutions containing food dyes and surfactants. The influence of surfactants (SDS � sodium dedecil sulphate, SO � sodium octanoate) in the separation of synthetic food dyes (E104 � quinoline yellow) was analyzed. Polysulfone and polysulfone-polyaniline membranes were used. Dye and surfactant concentrations used were 10% (equivalent to 100g/m3). The pressures used in the ultrafiltration process were 0.1, 0.2 and 0.3 MPa. When dye containing solutions were passed through the membranes, an increase in their flux was observed. The presence of surfactants in the solutions lead to a decline in flux when pressures of 0.1 and 0.2 MPa were used, but an improvement could be seen as the pressure increased to 0.3 MPa, for both dead-end and cross-flow filtration. Using only dead-end alternative, higher fluxes were achieved for both membranes, but it decreases with time due to accumulation on the membrane surface. The use of cross-flow filtration did not allow accumulation on the membrane surface so that the flux was constant in time.The use of anionic surfactants improved the food dye retention. The interactions between membranes and surfactants can be an important factor supporting the efficiency of the ultrafiltration.

Numerical Simulation of Filtration of Charged Oil Particles in Stationary and Rotating Tubular Membranes

2015 ◽  
Author(s):  
Sina Jahangiri Mamouri ◽  
Volodymyr V. Tarabara ◽  
André Bénard
Keyword(s):  
Flow Field ◽  
Electric Field ◽  
Electric Potential ◽  
Membrane Fouling ◽  
Membrane Surface ◽  
Cross Flow ◽  
Solid Cylinder ◽  
Permeate Flux ◽  
Cross Flow Filtration ◽  
Flow Filtration

Cross flow filtration (CFF) is a common membrane separation process with applications in food, biochemical and petroleum industries. In particular, membranes can be used for liquid-liquid separation processes such as needed in oil-water separation. A major challenge in cross flow filtration is membrane fouling. It can decrease significantly the permeate flux and a membrane’s efficiency. Membrane fouling can be mitigated by inducing shear on the membrane’s surface and this can be enhanced by inducing a swirl in the flow. In addition, a possible approach to improve membrane efficiency consists of repelling droplets/particles from the porous surface toward the centerline using a repulsive electric force. For this purpose, the surface of the membrane can be exposed to electric potential and droplets/particles are also induced to have the same electric charge. In this work, numerical simulations of charged non-deformable droplets moving within an axially rotating charged tubular membrane are performed. The results show that by increasing the electric potential on the membrane surface, the repelling force increases which obviously improves the grade efficiency of the membrane. However, the electric field gradients found in the flow field require large potentials on the membrane surface to observe a noticeable effect. Hence, a smaller solid cylinder is located in the centerline of the flow channel with zero potential. This solid cylinder enhances the electric field gradient in the domain which results in higher repelling forces and larger grade efficiency of the membrane at small potentials. The addition of a small cylinder in the flow field also improves the grade efficiency increases due to the higher shear stress near the membrane surface.

Evaluation of Virus Removal in Membrane Separation Processes Using Coliphage Qβ

1993 ◽  
Vol 28 (7) ◽  
pp. 9-15 ◽  
Author(s):  
Taro Urase ◽  
Kazuo Yamamoto ◽  
Shinichiro Ohgaki
Keyword(s):  
Membrane Separation ◽  
Membrane Surface ◽  
Cross Flow ◽  
Pond Water ◽  
High Concentration ◽  
Separation Processes ◽  
Surface Deposit ◽  
Virus Removal ◽  
Cross Flow Filtration ◽  
Flow Filtration

Virus removal in membrane separation processes was investigated by employing coliphage Qβ as a tracer. Several types of microfiltration membrane and ultrafiltration membrane were tested. Two types of filtration experiments were carried out; dead-end filtration and cross-flow filtration. The membrane surface deposits played an important role in the rejection of viruses in the filtration of activated sludge and pond-water, whereas acrylate polymer cake did not affect the rejection of Qβ. The leakage of ultrafiltration membranes was well examined by the high concentration of Qβ applied. The major part of the rejected coliphages were adsorbed onto the membrane and in its surface deposit.

Cross-Flow Ultrafiltration Used in Algal High Rate Oxidation Pond Treatment of Saline Organic Effluents with the Recovery of Products of Value

1992 ◽  
Vol 25 (10) ◽  
pp. 319-327 ◽  
Author(s):  
P. D. Rose ◽  
B. A. Maart ◽  
T. D. Phillips ◽  
S. L. Tucker ◽  
A. K. Cowan ◽  
...  
Keyword(s):  
Waste Treatment ◽  
Production Systems ◽  
Algal Cell ◽  
Cross Flow ◽  
Viable Cell ◽  
High Rate ◽  
Limiting Factor ◽  
Algal Biotechnology ◽  
Cross Flow Filtration ◽  
Flow Filtration

An algal high rate oxidation ponding process for treating organic s present in saline effluents has been described. The extreme halophile Dunaliella salina can be made to predominate in the system by manipulating salinity, producing products of value together with a waste treatment function. Application in treating tannery saline organic wastes was examined. Techniques appropriate for the harvesting of micro-algae from this and other algal production systems presents a limiting factor in the development of algal biotechnology. Cross-flow filtration was evaluated as a technique for micro-algal cell separation. Both microfiltration and ultrafiltration were found to produce effective algal removal from the medium, Cross-flow ultrafiltration with a polyethersulfone coated tubular filter produced effective separation with the production of cell concentrates in a viable condition. Flux rates of 30 - 40 LMH fall within acceptable levels for application in industrial processes. Cell shattering observed with microfiltration precludes its use for recovering whole or viable cell concentrates.

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