Investigation of biofouling resistant poly(vinyl alcohol)/cellulose acetate ultrafiltration membranes (original) (raw)
Related papers
Journal of Applied Polymer Science, 1999
Ultrafiltration (UF) membranes were prepared from poly(vinyl chloride) (PVC), carboxylated poly(vinyl chloride) (CPVC), and PVC/CPVC blends by the phaseinversion method. The physical structure of the membranes was characterized by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The fouling characteristics of all the three membranes and acrylamide (AA)-grafted PVC membranes were characterized by ultrafiltration of bovine serum albumin (BSA) solution over a range of pH and of salt concentrations. Maximum adsorption of the protein on the membrane occurred near the isoelectric point of BSA and in the presence of the salts. The charge on BSA appears to be a dominant factor in determining the fouling. The UF results are explained in terms of nature of the membrane polymer, and effect of different ionic environments on the conformational changes of the protein. The ultrafiltration fluxes are correlated by a model based on the membrane resistance and the time-dependent resistance of the concentration polarization layer of the protein. The values of a mass transfer coefficient and concentration polarization were determined. Zeta potential of the membranes were also determined before and after the UF.
Microporous and Mesoporous Materials, 2017
Polyethersulfone (PES) ultrafiltration membrane with enhanced simultaneous permeability and fouling eresistance property was prepared using a new synthesized aromatic polyamide (PA-6) as an additive. A series of asymmetric membranes were prepared by adding different amounts of PA-6 to the casting solution using the phase inversion induced by immersion precipitation method. Attenuated total reflection-Fourier transform infrared spectra (ATR-FTIR) and water contact angle measurement confirmed the PA-6 enrichment at the membrane surface and increased the membrane hydrophilicity and wettability. The SEM images elucidated the effect of PA-6 addition on the PES membrane morphology by increasing the pore density. The results of filtration performance, which carried out by dead-end filtration of bovine serum albumin (BSA) solution showed that the permeability and fouling resistance property was improved by optimizing the PA-6 content. When the PA-6 content was 2 wt%, the permeability reached approximately 10 times over the pure PES membrane. In comparison to the blend membrane of PES and 2 wt% of polyvinyl pyrrolidone (PVP), the blend membrane of 2 wt% of PA-6 showed significant flux recovery ability. The rejection of all the blended membranes was approximately at high point over 95%. In addition, the results were compared with those obtained using PVP as a usual additive. Although the PVP blended membranes exhibited higher permeability, they showed lower antifouling properties. Finally, a membrane with 1 wt% PVP and 1 wt% PA-6 was prepared and showed the best performance regarding improved permeability and antifouling properties.
Korean Journal of Chemical Engineering, 2015
The effect of polyacrylonitrile-g-poly (vinyl alcohol) (PAN-g-PVA) copolymer additive on the properties of PAN-based hollow fiber UF membranes was studied. The resulting hollow fiber membranes were characterized with respect to structural morphology, surface properties, and proteins rejection in order to investigate the impact of PANg -PVA copolymer composition (presented at different PAN : PANg -PVA ratio) in the UF membrane on the separation and antifouling properties. Results showed that the hollow fiber membrane prepared from the highest composition of PANg -PVA copolymer (PAN : PANg -PVA 80 : 20) was able to produce pure water flux as high as 297 L/m 2 •hr in comparison to 41 L/m 2 •hr reported in control PAN membrane when tested at 1 bar. Fouling experiments performed using bovine serum albumin (BSA), albumin from chicken egg (CE) and trypsin indicated that the blend membranes with higher surface coverage of hydrophilic PVA (34-60%) were more excellent in minimizing protein fouling, which might be correlated with the formation of hydrophilic PVA layer on their surface. Although increase in membrane hydrophilicity upon PANg -PVA copolymer incorporation might be the main reason contributing to improved membrane antifouling properties, the changes in membrane surface roughness and pore size could not be completely ruled out to influence membrane anti-fouling resistance during protein filtration.
Novel modified PVDF ultrafiltration flat-sheet membranes
Journal of Membrane Science, 2012
Polyvinylidene fluoride (PVDF) ultrafiltration membranes were modified using a new type of hydrophilic polyurethane additive, called L2MM. During phase inversion L2MM migrates to the membrane surface and functions as both a pore former and surface modifier. L2MM improved the surface hydrophilicity and significantly increased the PVDF membrane's pure water permeation (PWP) rate. PVDF membranes were modified with two L2MMs: L2MM(PEG-600) and L2MM(PEG-200). PWP tests, contact angle measurements, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM) were used to assess the impact of L2MM type, L2MM concentration and PVDF concentration on the performance and characteristics of modified PVDF membranes. XPS analysis and contact angle measurements indicated that the L2MM migrated to the membrane surface and the contact angle decreased by up to 19%. SEM and AFM images were used to investigate the relation between surface morphology and ultimate performance. The L2MMs had a significant effect on flux; increasing the L2MM concentration improved membrane PWP fluxes up to a maximum with further increases resulting in flux decreases. Both L2MM(PEG-200) and L2MM(PEG-600) increased the final PWP flux of modified PVDF membranes up to 6.5 times that of the control membranes. Furthermore, L2MM(PEG-200) increased the 100 kDa polyethylene oxide (PEO) separation from 88 to 96% compared to the control membrane.
2008
In this work, shifting the properties to reverse osmosis (RO) region, morphology and ion rejection of modified membranes based on polyamides/poly(vinyl alcohol), PA/PVA, blends were studied. The solubility parameters of the polymeric materials, δ h and δ d which represent hydrophobic and hydrophilic properties can be employed to choose the polymeric materials for the RO membranes. Large void cavities (between 150 to 250 nm) were observed in the substructure for the lower polymer concentrations in the casting solution. Feed water samples exhibited high concentrations of Cland HCO 3 as the major anions and Ca 2+ as the major cation. The observed rejection varied from 69% to 100% for Ca 2+ , Mg 2+ , Cl-, SO 4 2-, Yeast & Mold and Total Coliform. Nitrate showed lower rejection.
Polymers
In the present work, the novel dense and supported membranes based on polyvinyl alcohol (PVA) with improved transport properties were developed by bulk and surface modifications. Bulk modification included the blending of PVA with chitosan (CS) and the creation of a mixed-matrix membrane by introduction of fullerenol. This significantly altered the internal structure of PVA membrane, which led to an increase in permeability with high selectivity to water. Surface modification of the developed modified dense membranes, based on composites PVA-CS and PVA-fullerenol-CS, was performed through (i) making of a supported membrane with a thin selective composite layer and (ii) applying of the layer-by-layer assembly (LbL) method for coating of nano-sized polyelectrolyte (PEL) layers to increase the membrane productivity. The nature of polyelectrolyte type-(poly(allylamine hydrochloride) (PAH), poly(sodium 4-styrenesulfonate) (PSS), poly(acrylic acid) (PAA), CS), and number of PEL bilayers (2-10)-were studied. The structure of the composite membranes was investigated by FTIR, X-ray diffraction, and SEM. Transport properties were studied during the pervaporation separation of 80% isopropanol-20% water mixture. It was shown that supported membrane consisting of hybrid layer of PVA-fullerenol (5%)-chitosan (20%) with five polyelectrolyte bilayers (PSS, CS) deposited on it had the best transport properties.
Surface Treatment of Polymer Membranes for Effective Biofouling Control
Membranes
Membrane biofouling is the consequence of the deposition of microorganisms on polymer membrane surfaces. Polymeric membranes have garnered more attention for filtering and purifying water because of their ease of handling, low cost, effortless surface modification, and mechanical, chemical, and thermal properties. The sizes of the pores in the membranes enable micro- and nanofiltration, ultrafiltration, and reverse osmosis. Commonly used polymers for water filter membranes are polyvinyl chloride (PVA), polyvinylidene fluoride (PVDF), polyamide (PA), polyethylene glycol (PEG), polyethersulfone (PES), polyimide (PI), polyacrylonitrile (PAN), polyvinyl alcohol (PA), poly (methacrylic acid) (PMAA), polyaniline nanoparticles (PANI), poly (arylene ether ketone) (PAEK), polyvinylidene fluoride polysulfone (PSF), poly (ether imide) (PEI), etc. However, these polymer membranes are often susceptible to biofouling because of inorganic, organic, and microbial fouling, which deteriorates the mem...
2020
The pollution of hydric sources by pharmaceuticals is an issue in many countries, particularly in Brazil. The presence of these substances causes deleterious effects on the environment and human health. One of the main sources of this contamination is domestic sewage, due to the expressive amount of medicines released in their unaltered form. Unfortunately, traditional wastewater treatment is not effective for the removal of pharmaceuticals and, for this reason, membrane technology is an attractive alternative to overcome this issue. In this regard, hydrophilic polymers, such as poly(vinyl alcohol) (PVA), are the most suitable. However, their high affinity with water causes intense swelling, leading to severe modifications in the membrane properties. In view of all these facts, the present work evaluated the swelling of PVA-based membranes, with the aim of finding the membrane preparation method that has the lowest swelling, thereby providing the most suitable characteristics for ph...