Synthesis Aspects in the Design of Responsive Membranes

Husson, Scott M.

doi:10.1002/9781118389553.ch4

Cited by 11 publications

(12 citation statements)

References 64 publications

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“…Stimuli-responsive membranes change their physical properties in response to changes in environmental conditions, such as pH, solution ionic strength, temperature, concentration of specific chemical species, electric and magnetic field [1][2][3]. Changes in the physical properties of the membrane in response to changed environmental conditions can lead to changes in the mass transfer and interfacial properties of the membrane.…”

Section: Introductionmentioning

confidence: 99%

“…Among the stimuli that can be used to control the response of the system, temperature and pH-responsive factors have drawn much attention. In general, responsive membranes are formed from stimuli-sensitive materials (polymers or copolymers) or by modification of existing membranes by various chemical/physical processes to incorporate stimuli-responsive polymers [1,2]. An example of a pH-sensitive polymer is the natural polymer chitosan.…”

Section: Introductionmentioning

confidence: 99%

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pH-responsive hydrogel membranes based on modified chitosan: water transport and kinetics of swelling

2015

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pH-responsive membranes prepared by treating chitosan (Ch) with glutaraldehyde (GA) or with GA and sulfuric acid (SA) were studied. The structure and properties of the membranes were characterized by Fourier transform infrared (FTIR) spectroscopy, wide-angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and elemental analysis. The effect of the cross-linking process both on the dynamic swelling behaviour of the hydrogel membranes and on the mechanism of water transport through those membranes was investigated in buffer solutions of different pH (1.2-9.5). The mechanism of water transport through the hydrogel chitosan membranes was affected by membrane composition and pH of the swelling medium. Non-cross-linked Ch membrane showed a non-Fickian swelling behaviour in the pH range 6.5-9.5. Chitosan membrane cross-linked with GA (Ch/GA) showed less-Fickian or Fickian swelling behaviour in all buffer solutions. In the case of chitosan membrane cross-linked with GA and SA (Ch/GA/SA), at low pH (lower than the pK a of the hydrogel) the water transport was controlled more by polymer relaxation than by penetrant diffusion. The experimental data clearly suggested that the swelling process in all buffer solutions obeyed second-order kinetics. Values of an apparent swelling rate constant for Ch/ GA and Ch/GA/SA membranes were of the same order of magnitude for acidic and neutral swelling media but they increased for alkaline solutions.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

pH-responsive hydrogel membranes based on modified chitosan: water transport and kinetics of swelling

2015

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“…The physical coating with a conductive polymer generally leads to variations in membrane swelling degree and changes in membrane permselectivity [ 33 , 34 ]. Alternatively, functional polymers, as well known as polymer brushes , can be attached in a controlled manner on the membrane surfaces or within membrane pores by physical adsorption or covalent bonds [ 35 , 36 , 37 , 38 ]. Polymer brushes can be covalently attached to membrane surfaces and pores either by ‘grafting-from’ methods or by ‘grafting-to’ techniques.…”

Section: Electro-conductive Membranesmentioning

confidence: 99%

Electro-Conductive Membranes for Permeation Enhancement and Fouling Mitigation: A Short Review

et al. 2017

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The research on electro-conductive membranes has expanded in recent years. These membranes have strong prospective as key components in next generation water treatment plants because they are engineered in order to enhance their performance in terms of separation, flux, fouling potential, and permselectivity. The present review summarizes recent developments in the preparation of electro-conductive membranes and the mechanisms of their response to external electric voltages in order to obtain an improvement in permeation and mitigation in the fouling growth. In particular, this paper deals with the properties of electro-conductive polymers and the preparation of electro-conductive polymer membranes with a focus on responsive membranes based on polyaniline, polypyrrole and carbon nanotubes. Then, some examples of electro-conductive membranes for permeation enhancement and fouling mitigation by electrostatic repulsion, hydrogen peroxide generation and electrochemical oxidation will be presented.

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“…Functionalizing membranes that can be responsive to various stimuli like temperature, pH, and electric fields, promises even more unique applications. 15, 16 For porous membranes, a typical functionalization involves grafting or cross-linking of stimuli-responsive functional polymers inside the membrane pores. Such responsiveness allows reversible changes in selectivity and permeation across the membrane in response to environmental factors, such as pH, which can deprotonate functional polymers, absorbing water while decreasing membrane’s pore diameter and permeability.…”

Section: Introductionmentioning

confidence: 99%

Layer-by-layer assembled membranes with immobilized porins

et al. 2017

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With the synthesis and functionalization of membranes for selective separations, reactivity, and stimuli responsive behavior arises new and advanced opportunities. The integration of bio-based channels is one of these advancements in membrane technologies. By a layer-by-layer (LbL) assembly of polyelectrolytes, outer membrane protein F trimers (OmpF) or “porins” from Escherichia coli with a central pore of ~2 nm diameter at its opening and ~0.7 × 1.1 nm at its constricted region are immobilized within the pores of poly(vinylidene fluoride) microfiltration membranes, as opposed to traditional ruptured lipid bilayer or vesicles processes. These OmpF-membranes demonstrate selective rejections of non-charged organics over ionic solutes, allowing the passage of salts up to 2 times higher than traditional nanofiltration membranes starting with rejections of 84% for 0.4–1.0 kDa organics. The presence of charged groups in OmpF membranes also leads to pH-dependent salt rejection through Donnan exclusion. These OmpF-membranes also show exceptional durability and stability, delivering consistent and constant permeability and recovery for over 160 h of operation. Characterization of solutions containing OmpF, and membranes were conducted during each stage of the process, including detection by fluorescence labelling (FITC), zeta potential, pH responsiveness, flux changes, and rejections of organic-inorganic solutions.

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Synthesis Aspects in the Design of Responsive Membranes

Cited by 11 publications

References 64 publications

pH-responsive hydrogel membranes based on modified chitosan: water transport and kinetics of swelling

pH-responsive hydrogel membranes based on modified chitosan: water transport and kinetics of swelling

Electro-Conductive Membranes for Permeation Enhancement and Fouling Mitigation: A Short Review

Layer-by-layer assembled membranes with immobilized porins

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