Fouling resistant, high flux nanofiltration membranes from polyacrylonitrile-graft-poly(ethylene oxide) (original) (raw)
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Journal of Colloid and Interface Science, 2019
While polyacrylonitrile (PAN) has been widely used to prepare membranes, it is still not handy to prepare PAN integrally skinned asymmetric (ISA) nanofiltration (NF) membrane via direct immersion precipitation phase inversion method. Herein, a low-cost and commercial polyacrylonitrile-co-methylacrylate, P (AN-coMA), was demonstrated to prepare ISA NF membranes via a one-step immersion precipitation phase inversion process. It was found that increasing P(AN-coMA) concentration in NMP can shift the membranes from ultrafiltration (UF) to NF range. The addition of a co-solvent in dope could further improve dye rejection. Effects of solvent (NMP or DMF)/co-solvent (THF and 1,4-dioxane) type and mass ratio in dope solution on membrane separation performance were further investigated. The membrane prepared from a 20% polymer concentration and a NMP/1,4-dioxane ratio of 3:1 showed 87.4% methyl orange (MO) rejection and 98.3% rose bengal (RB) rejection, and simultaneously a relatively high water permeance of 55.22 L m À2 h À1 bar À1. Increase in the content of co-solvent in solvent/co-solvent mixture would depress the formation of macrovoids, lead to a dense top layer and contribute to high dye rejections. The low-cost and one-step process to prepare P(AN-coMA) ISA NF membranes disclosed in this study paved a new way for sustainable molecular separation.
Membranes for organic solvent nanofiltration based on pre-assembled nanoparticles
A new class of organic solvent nanofiltration (OSN) membranes has been fabricated by assembling nano-sized polymer particles with methacrylate moieties onto the surface of crosslinked polyimide ultrafiltration support membranes. Multiple layers of these nanoparticles create a separation film functionally similar to the top layer of an asymmetric OSN membrane. Nanoscale interstitial spaces formed between the particles serve as permeation channels. In principle, manipulating the size of the nanoparticles can be used to control the dimensions of the interstitial spaces through which permeation occurs. Two different sizes of nanoparticles-120 2 and 300 nm-were used. As expected, membrane separation performance changed with the size of nanoparticles employed due to the changes in interstitial dimensions. Crosslinked polyimide ultrafiltration membranes prepared by phase inversion were coated with successive layers of nanoparticles by spin coating. After coating the nanoparticles were crosslinked by photo initiated free radical polymerization using ultraviolet light (365nm wavelength). In addition to the size of the nanoparticles, the separation performance was also manipulated by changing the thickness of the nanoparticle layer. Membranes were characterized using scanning electron microscopy. The nanofiltration performance of these membranes was evaluated in solvents such as acetone and toluene. The molecular weight cutoff (MWCO) of the membranes was from 200-1,000 g.mol-1 depending upon the nanoparticle diameter and thickness of the nanoparticle layer. Thus membranes with graded nanoscale porosities were successfully fabricated from interconnected nanoparticles providing control over membrane permeation performance. This paper emphasises the fabrication of these membranes by using different sizes of nanoparticles, varying nanoparticle layer thickness, and evaluating the nanofiltration performance of the resulting membranes. Structural studies were undertaken using scanning electron microscopy. 2. Materials and methods 2.1 Materials The monomers, N-isopropylacrylamide (NIPAM) and 2-(hydroxy) ethyl methacrylate (HEMA), the crosslinker N, N'-Methylenebis(acrylamide) (BIS), the stabilizer dodecyl sulfate sodium salt (SDS) and triethylamine (TEA) used for the microgel synthesis were purchased from Sigma-Aldrich (Germany). 2, 2'-Azobis (2-methylpropionitrile) (AIBN) and acryloyl chloride (AcCl) were obtained from Acros Organics and Fluka, respectively. The organic solvents used were of HPLC or analytical grade, and were purchased from Sigma-Aldrich (Germany). Milli-Q water (18.2 MΩ) was used in all experiments. P84 polyimide was purchased from HP Polymer GmbH (Austria) and used without any pretreatment. Organic solvents (all obtained from Sigma-Aldrich, UK) used to prepare the membranes and for filtration experiments were N, N-dimethylformamide (DMF), methanol, toluene, acetone and isopropanol (IPA). The crosslinker for the ultrafiltration support membranes was 1, 6-hexanediamine (HDA) purchased from Sigma-Aldrich (UK). Commercial membranes Starmem 122 (MWCO~220 gmol-1), Puramem 280 (MWCO~280 gmol-1) and S380 (MWCO~380 gmol-1) (MWCO as provided by the supplier) were purchased from Evonik Membrane Extraction Technology Ltd (UK).
Engineering and Technology Journal
The importance of two types of Nanocomposite membrane in dye effluent treatment is reviewed Nanocomposite Membranes have: high dye effluent separation efficiency, anti-fouling, and stability The importance of the interaction mechanism between polymeric materials and nanoparticles is presented The influence of incorporated nanoparticles on long-term performance and stability is discussed. Dyes are an essential group of organic pollutants with a long history of harming aquatic life and humans. Prior to disposal, polluted dye wastewater must be adequately treated to prevent adverse impacts on persons and the environment. Although there are several techniques for dye removal, most of them share a similar drawback: they generate secondary pollution to the environment. Membrane separation is highlighted in this article because it is one of the most efficient dye removal techniques available nowadays due to its high removal capacity, ease of operation, and clean water generation. Polymeric membranes are frequently used in membrane-based separations because of their greater flexibility, ease of pore formation process, and lower cost than other membrane materials. Although polymeric membranes are preferable materials for membrane production, they are usually hydrophobic and, hence, sensitive to fouling. Therefore, much research has been done to modify the polymeric membrane. More recently, metal nanoparticles (NPs) have been introduced to the polymer matrix to minimize fouling potential and enhance membrane performance. This study describes several polymeric membranes utilized in dye separation that have been modified using nanomaterial. Also, the study illustrates how adding these components affects the membranes' performance in rejecting the dye. Additionally, it highlights the importance of membrane-nanomaterial interactions and the effect of these materials' additions on membrane performance over time.
A new nanofiltration/low ultrafiltration membrane was prepared by tangential filtration of protein solutions on macroporous ceramic supports. A unique feature of these membranes is their ability to work under mild conditions (∆P and tangential velocity). Moreover they are biocompatible and may be easily regenerated. All these characteristics make them very good for concentration and purification of food stuff, biological and pharmaceutical solutions.
Journal of Chemical Technology & Biotechnology, 2012
BACKGROUND: Low energy and less expensive membrane based separation of acetic acid-water mixtures would be a better alternative to conventional separation processes. However, suitable acid resistant membranes are still lacking. Thus, the objective of the present study was to develop mixed matrix membrane (MMM) which would allow high flux and water selectivity over a wide range of feed concentrations of acid in water. RESULTS: Three MMMs, namely PANBA0.5, PANBA1.5 and PANBA3 were made by emulsion copolymerization of acrylonitrile (AN) and butyl acrylate (BA) with 5.5 : 1 comonomer ratio and in situ incorporation of 0.5, 1.5 and 3 wt%, sodium montmorilonite (Na-MMT) nanofillers, respectively. For a feed concentration of 99.5 wt% of acid in water the membranes show good permeation flux (2.61, 3.19, 3.97 kg m −2 h −1 µm −1 , for PANBA0.5, PANBA1.5 and PANBA3 membrane, respectively) and very high separation factors for water (1473, 1370, 1292 for PANBA0.5, PANBA1.5 and PANBA3 membrane, respectively) at 30 • C. Similarly for a dilute acid-water solution, i.e. for 71.6 wt% acid the membrane showed a very high thickness normalize flux (8.67, 9.44, 11.56 kg m −2 h −1 µm −1 , for PANBA0.5, PANBA1.5 and PANBA3 membrane, respectively) and good water selectivity (101.7, 95.3, 79 for PANBA0.5, PANBA1.5 and PANBA3 membrane, respectively) at the same feed temperature. The permeation ratio, permeability, diffusion coefficient and activation energy for permeation of the membranes were also estimated. CONCLUSION: Unlike most of the reported membranes, the present MMMs allowed high flux and selectivity over a wide range of feed concentrations. These membranes may also be effective for separating other similar organic-water mixtures.
Characterisation of nanofiltration membranes for the separation of aqueous dye-salt solutions
Desalination, 1992
Atomic force microscopy (AFM) has been used to characterize five commercial nanofiltration (NF) membranes from three companies. High-resolution 3D images of the membranes were obtained without preparative treatment that may affect the membrane surface. Obtained images have been filtered to overcome the effect of tip convolution and the noises. Two sizes of the images were obtained 2 I~m x 2 gm and small sizes. The first images were used to find the surface morphology data such as average roughness, mean height, root mean square (RMS), and maximum peak-to-valley. The small size images showing visible pores were used to determine the pore size and pore size distributions, which were used to calculate porosity of membranes. A fitted line using lognormal distributions was used to represent the pore size distribution of the nanofiltration membranes. The results show that the Iognormal distribution is fitted well with AFM experimental data.
2019
L’objectif de cette etude etait d’ameliorer les performances de separation OSN de membranes commerciales en vue d’applications en metathese dans laquelle des catalyseurs hautement dilues sont utilises. Dans ce travail, des membranes polymeres commerciales ont d'abord ete etudiee pour caracteriser leurs performances dans des milieux organiques en utilisant des melanges binaires tres dilues solute-solvant. Sur la base d'une revue de la litterature, il a ete montre que la membrane PERVAP4060, dont le PDMS est la couche active dense etait un candidat prometteur pour la nanofiltration milieu organique (OSN). En tant que membrane poreuse, les supports commerciaux AMS et PAN ont egalement ete pris en compte. Dans cette etude, nous avons considere la modification sur la surface pour conserver les proprietes de matrice polymere. Les multicouches de plasma Ar/O2 et/ou de polyelectrolytes ont ete utilisees pour la preparation de membranes prototypes. Les membranes non modifiees et modi...
Antifouling performance of poly(acrylonitrile)-based membranes: From green synthesis to application
The Journal of Supercritical Fluids, 2011
In order to develop clean ultrafiltration membranes able to prevent the fouling of biological compounds in filtration processes, poly(ethylene glycol) methyl ether acrylate (PEGA) was grafted to poly(acrylonitrile) (PAN) by free-radical polymerization in supercritical carbon dioxide (scCO 2 ) and the grafted copolymer was blended with PAN to fabricate porous membranes using scCO 2 -induced phase inversion method. Fourier transform infrared (FT-IR) analysis, 1 H nuclear magnetic resonance ( 1 H NMR) and differential scanning calorimetry (DSC) confirmed that the poly(acrylonitrile)-graft-poly(ethylene oxide) (PAN-g-PEO) was successfully synthesized, for the first time, in scCO 2 . The effect of increasing PEGA content on the initial monomer feed mixture on graft polymer morphology and average molecular weight was studied. Blended membranes with different PEGA contents were investigated by scanning electron microscopy (SEM), mercury porosimetry and dynamical mechanical analysis (DMA) to characterize their morphological, physico-chemical and mechanical properties. Moreover, water contact angle measurements, pure water permeability and filtration experiments were performed to evaluate membrane hydrophilicity and fouling resistance properties. Permeation experiments of model foulants, bovine serum albumin (BSA) and starch solutions were used to investigate antifouling character of blend membranes at different pHs. PAN: showed to be the ultrafiltration membrane with best performance. Furthermore, comparing with conventional technologies blended membranes of PAN:PAN-g-PEO prepared by a scCO 2assisted process showed enhanced hydrophilicity, larger protein and starch solution permeabilities and good resistance to irreversible fouling, indicating that the technology is an efficient process to prepare fouling resistant membranes for biomacromolecule separations.
Separation and Purification Technology, 2013
Nanofiber membranes were fabricated by electrospinning poly(vinylidene fluoride). The electrospun nanofiber membranes were further modified by grafting of acrylic acid (AA) and methacrylic acid (MAA) over the surfaces of the membranes. Plasma AA graft was attempted only, and the results indicated the partial membrane pore filling with grafted AA. For MAA grafting, chemically induced polymerization using benzoyl peroxide and hydrogen peroxide was attempted. The combination of plasma and chemically induced MAA graft polymerization was also attempted. The membranes were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and static contact angle (SCA) measurement. SEM surface analysis indicated partial pore narrowing of grafted membranes. The average pore size was reduced from 0.97 lm for the untreated membrane to 0.15 lm for the two step plasma and chemically induced grafted membranes. XPS analysis confirmed that grafting has taken place on the top surface of the membranes. The surfaces of the grafted membrane were significantly hydrophilic as observed by SCA. It was also found that the combination of plasma and chemically induced grafting using hydrogen peroxide was the most effective in terms of flux and selectivity. The grafting reduced the pore size by filling the pores of the original membranes by the graft polymers. This practice resulted in producing tight micro-filtration (MF) membranes from loose MF ones. An impressive high water flux of 150 kg/h m 2 at an operating pressure of 4 psig, and a 79% removal of polyethylene oxide (molecular weight 400 kilo-Daltons) were achieved.
Membranes
This study presents the preparation of hybrid nanofiltration membranes based on poly(1,4-phenylene ether ether sulfone), polyacrylonitrile, poly(vinyl pyrrolidone), and SBA-15 mesoporous silica. Laser treatment of polymeric solutions to enhance the hydrophilicity and performance of membranes was investigated. The membranes’ structure was characterized using scanning electron (SEM) and atomic force (AFM) microscopy and contact angle measurements. The addition of PAN in the casting solution produced significant changes in the membrane structure, from finger-like porous structures to sponge-like porous structures. Increased PAN concentration in the membrane composition enhanced the hydrophilicity of the membrane surface, which also accounted for the improvement in the antifouling capabilities. The permeation of apple pomace extract and the content of polyphenols and flavonoids were used to evaluate the efficacy of the hybrid membranes created. The results showed that the hybrid nanofil...