Sustainable Membrane Production through Polyelectrolyte Complexation Induced Aqueous Phase Separation

Baig, Muhammad Irshad; Durmaz, Elif Nur; Willott, Joshua D.; Vos, Wiebe M. de

doi:10.1002/adfm.201907344

Cited by 85 publications

(79 citation statements)

References 33 publications

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“…Our research group recently demonstrated that it is also possible to prepare membranes by casting homogeneous PE mixtures instead of coacervates. 47 A switch between two extreme pH regimes was used to control the complexation of a strong polyanion and a weak polycation. Polymer molecular weight, polymer concentration, and coagulation bath salinity were the factors that gave a great control over the membrane structure and resulted in membranes ranging from microfiltration (MF) type to nanofiltration (NF) type.…”

Section: Introductionmentioning

confidence: 99%

“…Herein, a simple change in salt concentration is used to control complexation instead of switching between extreme pH values as was used in our earlier work. 47 Therefore, by use of a salt switch, the membrane formation conditions are milder and the requirement for using a weak and strong PE pair is removed. In this study, a homogeneous mixture of the two strong PEs is prepared at a high salinity where the entropic driving force for complexation is eliminated.…”

Section: Introductionmentioning

confidence: 99%

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Polyelectrolyte Complex Membranes via Salinity Change Induced Aqueous Phase Separation

Durmaz

Baig

Willott

et al. 2020

ACS Appl. Polym. Mater.

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Polymeric membranes are used on very large scales for drinking water production and kidney dialysis, but they are nearly always prepared by using large quantities of unsustainable and toxic aprotic solvents. In this study, a water-based, sustainable, and simple way of making polymeric membranes is presented without the need for harmful solvents or extreme pH conditions. Membranes were prepared from water-insoluble polyelectrolyte complexes (PECs) via aqueous phase separation (APS). Strong polyelectrolytes (PEs), poly(sodium 4-styrenesulfonate) (PSS), and poly(diallyldimethylammonium chloride) (PDADMAC) were mixed in the presence of excess of salt, thereby preventing complexation. Immersing a thin film of this mixture into a low-salinity bath induces complexation and consequently the precipitation of a solid PEC-based membrane. This approach leads to asymmetric nanofiltration membranes, with thin dense top layers and porous, macrovoid-free support layers. While the PSS molecular weight and the total polymer concentrations of the casting mixture did not significantly affect the membrane structure, they did affect the film formation process, the resulting mechanical stability of the films, and the membrane separation properties. The salt concentration of the coagulation bath has a large effect on membrane structure and allows for control over the thickness of the separation layer. The nanofiltration membranes prepared by APS have a low molecular weight cutoff (<300 Da), a high MgSO 4 retention (∼80%), and good stability even at high pressures (10 bar). PE complexation induced APS is a simple and sustainable way to prepare membranes where membrane structure and performance can be tuned with molecular weight, polymer concentration, and ionic strength.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Polyelectrolyte Complex Membranes via Salinity Change Induced Aqueous Phase Separation

Durmaz

Baig

Willott

et al. 2020

ACS Appl. Polym. Mater.

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“…For example, cellulose [ 46 ], poly(lactic acid) (PLA) [ 47 ], bamboo fiber, chitosan, and others [ 48 , 49 , 50 , 51 , 52 ]. Green polymers have been investigated to minimize the use of petroleum-derived polymers and meet the performance requirements of membranes [ 53 , 54 , 55 ]. These polymers are derived from natural products, which significantly decrease the carbon footprint of the manufacturing process [ 56 ].…”

Section: Membrane Fabricationmentioning

confidence: 99%

Polymers and Solvents Used in Membrane Fabrication: A Review Focusing on Sustainable Membrane Development

et al. 2021

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(1) Different methods have been applied to fabricate polymeric membranes with non-solvent induced phase separation (NIPS) being one of the mostly widely used. In NIPS, a solvent or solvent blend is required to dissolve a polymer or polymer blend. N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAc), dimethylformamide (DMF) and other petroleum-derived solvents are commonly used to dissolve some petroleum-based polymers. However, these components may have negative impacts on the environment and human health. Therefore, using greener and less toxic components is of great interest for increasing membrane fabrication sustainability. The chemical structure of membranes is not affected by the use of different solvents, polymers, or by the differences in fabrication scale. On the other hand, membrane pore structures and surface roughness can change due to differences in diffusion rates associated with different solvents/co-solvents diffusing into the non-solvent and with differences in evaporation time. (2) Therefore, in this review, solvents and polymers involved in the manufacturing process of membranes are proposed to be replaced by greener/less toxic alternatives. The methods and feasibility of scaling up green polymeric membrane manufacturing are also examined.

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“…One method uses a combination of strong and weak polyelectrolytes. [27,29] In contrast to strong polyelectrolytes, the charge of a weak polyelectrolyte strongly depends on the pH. Therefore, the complexation can be suppressed by adjusting the pH and can be induced by a pH shift.…”

Section: Introductionmentioning

confidence: 99%

Polyelectrolyte Complex Tubular Membranes via a Salt Dilution Induced Phase Inversion Process

et al. 2021

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Tubular membrane geometries are key elements of many industrial filtration applications and artificial organs. Established processes to fabricate polymeric membranes require the use of organic solvents, which are prone to be phased out due to stricter regulations. In the quest of developing solvent‐free alternative fabrication processes, polyelectrolyte complex (PEC) membranes are recently discovered, offering a promising alternative. While flat sheet PEC membranes are successfully fabricated, tubular or hollow fiber geometries remain a material engineering challenge. For the first time, the organic solvent‐free fabrication of PEC tubular membranes in a dry‐jet wet spinning process is demonstrated. The aqueous polymer solution comprising the polyanion—poly(sodium‐4‐styrenesulfonate) (PSS), the polycation—poly(diallyldimethylammonium‐chloride) (PDADMAC), and KBr is extruded with the water‐based bore fluid through a single‐orifice spinneret, passing an air‐gap before immersed into an aqueous coagulation bath. The phase inversion kinetics are influenced to form a defect‐free lumen separation layer through the addition of glycerol to the bore fluid. The resulting tubular membranes show reproducible nanofiltration membrane properties. They have a molecular cut‐off of 320 Da, are positively charged and retain salts with a characteristic salt retention hierarchy. This promising material engineering strategy motivates to continue the quest for smaller tubular dimensions toward hollow fibers.

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Sustainable Membrane Production through Polyelectrolyte Complexation Induced Aqueous Phase Separation

Cited by 85 publications

References 33 publications

Polyelectrolyte Complex Membranes via Salinity Change Induced Aqueous Phase Separation

Polyelectrolyte Complex Membranes via Salinity Change Induced Aqueous Phase Separation

Polymers and Solvents Used in Membrane Fabrication: A Review Focusing on Sustainable Membrane Development

Polyelectrolyte Complex Tubular Membranes via a Salt Dilution Induced Phase Inversion Process

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