Preparation, characterisation and performance evaluation of anti-biofouling property of carbon nanotube-polysulfone nanocomposite membranes (original) (raw)
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Journal of Membrane Science, 2013
Acid functionalized multi-walled carbon nanotube (MWCNT) was modified by three hydrophilic polymers during an in situ polymerization reaction. Citric acid (CA), acrylic acid (AA) and acrylamide (AAm) were polymerized on functionalized MWCNTs to achieve greater number of functional groups on MWCNTs. Fourier transform infrared spectroscopy (FTIR) validated the formation of hydroxyl, carboxyl and amide groups on MWCNTs. Mixed matrix membranes were prepared by introducing 0.1 wt% of acid functionalized and polymer modified MWCNTs into polyethersulfone (PES) membranes. Water permeability and antifouling capability of prepared membranes were compared. According to the results, mixed matrix membranes showed higher pure water flux compared to pristine PES membrane. Hydrophilicity of polymer modified MWCNT/PES nanocomposite membrane was improved for all three polymers. The results indicated that hyperbranched polycitricacid (PCA) on MWCNTs offered large number of functional groups and significantly improved membrane fouling resistance against whey proteins. Efficient dispersion of PCA modified MWCNT in casting solution led to smooth and hydrophilic membrane surface and consequently higher flux recovery ratio (95%). Existence of PCA dendrimers on MWCNT increased the carbon nanotubes compatibility with membrane bulk polymer and resulted in superior dispersion of nanofiller in membrane matrix and its surface. The morphology and surface characteristics of prepared membrane were investigated by field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and water contact angle (WCA) measurement.
In this study, polysulfone (PSf)/silver-doped carbon nanotube (Ag-CNT) nanocomposite membranes were prepared by a phase-inversion technique; they were characterized and evaluated for fouling-resistant applications with bovine serum albumin (BSA) solutions. Carbon nanotubes were doped with silver nanoparticles via a wet-impregnation technique. The prepared Ag-CNT nano-tubes were characterized with scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy, X-ray diffraction, Raman spectroscopy, and thermogravimetric analysis. The fabricated flat-sheet PSf/Ag-CNT nanocomposite membranes with different Ag-CNT loadings were examined for their surface morphology, roughness, hydrophilicity, and mechanical strength with SEM, atomic force microscopy, contact angle measurement, and tensile testing, respectively. The prepared composite membranes displayed a greater rejection of BSA solution (90%) and water flux stability during membrane compaction with a 10% reduction in water flux values (up to 0.4% Ag-CNTs) than the pristine PSf membrane. The PSf nanocomposite membrane with a 0.2% Ag-CNT loading possessed the highest flux recovery of about 80% and the lowest total membrane resistance of 56% with a reduced irreversible fouling resistance of 21%. V
International Journal of Nanomedicine
Purpose: Nanoporous membranes have been employing more than before in applications such as biomedical due to nanometer hexagonal pores array. Biofouling is one of the important problems in these applications that used nanoporous membranes and are in close contact with microorganisms. Surface modification of the membrane is one way to prevent biofilm formation; therefore, the membrane made in this work is modified with carbon nanotubes. Methods: In this work, nanoporous solid-state membrane (NSSM) was made by a two-step anodization method, and then modified with carbon nanotubes (NSSM-multi-wall carbon nanotubes [MWCNT]) by a simple chemical reaction. Techniques such as atomic force microscopy (AFM), energy dispersive X-ray (EDAX), field emission scanning electron microscopy (FESEM), Fourier-transform infrared spectroscopy (FTIR), contact angle (CA), surface free energy (SFE), protein adsorption, flow cytometry, and MTT assay were used for membrane characterization. Results: The BSA protein adsorption capacity reduced from 992.54 to 97.24 (μg mL-1 cm-2) after modification. The findings of flow cytometry and MTT assay confirmed that the number of dead bacteria was higher on the NSSM-MWCNT surface than that of control. Adsorption models of Freundlich and Langmuir and kinetics models were studied to understand the governing mechanism by which bacteria migrate to the membrane surface. Conclusion: The cell viability of absorbed bacteria on the NSSM-MWCNT was disrupted in direct physical contact with carbon nanotubes. Then, the dead bacteria were desorbed from the surface of the hydrophilic membrane. The results of this research showed that NSSM-MWCNT containing carbon nanotubes have significant antimicrobial and self-cleaning property that can be used in many biomedical devices without facing the eminent problem of biofouling.
Fabrication and antifouling behaviour of a carbon nanotube membrane
In this work, a novel approach is used to synthesize an iron oxide doped carbon nanotube (CNT) membrane, with the goal of fully utilizing the unique properties of CNTs. No binder is used for the synthesis of the membrane; instead , iron oxide particles serve as a binding agent for holding the CNTs together after sintering at high temperature. The produced membrane exhibited a high water flux and strong fouling resistance. In the first step, CNTs were impregnated with various loadings of iron oxide (1, 10, 20, 30 and 50%) via wet chemistry techniques. Impregnated CNTs were then compacted at 200 MPa and sintered at 1350 °C for 5 h to form a compact disc. The membranes were analysed by measuring their porosity, contact angle, diametrical compression test and water flux. The flux of pure water was observed to increase with an increase in iron oxide content. The permeate flux and rejection rate of sodium alginate (SA) were determined to predict the antifouling behaviour of the membrane. A maximum removal of 90 and 88% of SA was achieved for membranes with a 10 and 1% iron oxide content , respectively, after 3 h. A minor decline in the permeate flux was observed for all membranes after 4 h of operation.
Membranes
Despite extensive research efforts focusing on tackling membrane biofouling, one of the biggest problems associated with membrane technology, there has been little headway in this area. This study presents novel polyethersulfone (PES) membranes synthesized via a phase inversion method at incremental loadings of functionalized oxidized multiwalled carbon nanotubes (OMWCNT) along with 1 wt. % arabic gum (AG). The synthesized OMWCNT were examined using scanning electron microscopy and transmission electron microscopy for morphological changes compared to the commercially obtained carbon nanotubes. Additionally energy-dispersive X-ray spectroscopy was carried out on the raw and OMWCNT materials, indicating an almost 2-fold increase in oxygen content in the latter sample. The cast PES/OMWCNT membranes were extensively characterized, and underwent a series of performance testing using bovine serum albumin solution for fouling tests and model Gram-positive (Bacillus subtilis) and Gram-nega...
Separation and Purification Technology, 2012
Multiwalled carbon nanotubes (MWCNTs) coated by anatase titanium dioxide (TiO 2 ) nanoparticles were synthesized via the precipitation of TiCl 4 precursor on the acid oxidized MWCNTs and used in preparation of nanocomposite polyethersulfone (PES) membranes. In this work, the effect of embedding TiO 2 coated MWCNTs in PES matrix on membrane morphology, properties and antibiofouling was presented and the obtained results were compared with the prepared oxidized MWCNTs and TiO 2 blended PES membranes. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses showed that the formed TiO 2 on the surface of MWCNTs had anatase nanostructure with size in the range of 10-20 nm. The scanning electron microscopy (SEM) images displayed a finger-like and porous structure for all NF membranes and showed that agglomeration of TiO 2 coated MWCNTs is very low. Contact angle measurements indicated that coating of TiO 2 nanoparticles on the surface of oxidized MWCNTs improved the hydrophilicity of the obtained membranes. The pure water flux of the blend membranes increased with the content of TiO 2 coated MWCNTs. Fouling resistances of membranes evaluated by whey solution filtration revealed that 0.1 wt.% TiO 2 coated MWCNTs membrane had the best antibiofouling properties due to its lowest surface roughness and synergistic photocatalytic activity induced by incorporated nanoparticles.
Elsevier, 2019
The ultrafiltration (UF) membrane in membrane bioreactor (MBR) technology is the mostsuitable in a wastewater treatment plant (WWTP). In MBR systems, bacteria consumeorganic waste for energy to survive. Hence, the membranes should be non-toxic to thebacteria but still possess antifouling capability. In this study, carbon nanotube (CNT)-and sulphonated CNT (SCNT)-blended ultrafiltration polyvinylidene fluoride (PVDF) mem-branes were fabricated with the aim of conserving the bacterial population. The successfulsulphonation of CNTs was observed by X-ray photoelectron spectroscopy, X-ray diffractionand transmission electron microscopy. The porosity of PVDF-CNT and -SCNT membraneswas 81 and 84%, respectively. The mean pore size was 50 and 60 nm, respectively, and thecorresponding water flux experiment was 360.43 and 680 L m−2h−1. The fouling recoveryratio (FRR) of the CNTs and SCNTs were 72.74 and 83.52%, respectively. In addition, theBSA (bovine serum albumin) rejection was 90% in the PVDF-SCNT. The CNTs and SCNTs(150 g/mL) had a significant antibacterial effect against Escherichia coli, Pantoea agglomerans,and Pseudomonas graminis isolated from full scale MBR with 60% cell viability. On the otherhand, PVDF-CNT and -SCNT membranes were nontoxic (90%, p < 0.0001) to the bacterial pop-ulation. Therefore, the fabricated UF membranes have sustainable antifouling propertiesand are non-toxic to bacteria. This study suggests that PVDF-CNT and -SCNT are promisingmaterials for MBR systems in WWTPs.
Journal of Membrane Science, 2011
This study describes the preparation, characterization and evaluation of performance and antifouling properties of mixed matrix nanofiltration membranes. The membranes were prepared by acid oxidized multiwalled carbon nanotubes (MWCNTs) embedded in polyethersulfone as matrix polymer. The hydrophilicity of the membrane was enhanced by blending MWCNTs due to migration of functionalized MWCNTs to membrane surface during the phase inversion process. The morphology studies of the prepared NF membranes by scanning electron microscopy (SEM) showed that very large macrovoids appeared in sub-layer by addition of low amount of functionalized MWCNT leading to increase of pure water flux. By using the proper amount of modified MWCNTs, it was possible to increase both the flux and the salt rejection of the membranes. In this work, the effect of CNT/polymer membrane for fouling minimization is presented. The antifouling performance of membranes fouled by bovine serum albumin (BSA) was characterized by means of measuring the pure water flux recovery. The results indicate that the surface roughness of membranes play an important role in antibiofouling resistance of MWCNT membranes. The membrane with lower roughness (0.04 wt% MWCNT/PES) represented the superior antifouling property. The salt retention by the negatively charged MWCNT embedded membrane indicated Donnan exclusion mechanism. The salt retention sequence for 0.04 wt% MWCNT was Na 2 SO 4 (75%) > MgSO 4 (42%) > NaCl (17%) after 60 min filtration.
Journal of water process engineering, 2019
We have prepared polyethersulfone (PES) nanocomposite membranes comprising of cloisite 30B clay, SiO 2 , TiO 2 , hydroxyl-functionalized multi-walled carbon nanotubes (MWCNTs-OH), and carboxyl-functionalized multi-walled carbon nanotubes (MWCNTs-COOH). The nanoparticulate at five different concentrations were added into the polymeric dope solutions including 15 or 18 wt% of PES, N,N-dimethylacetamide (DMAc) or 1methyl-2-pyrrolidone (NMP) as solvents, and 1 wt% of pore forming agent. These nanoparticulate may improve porosity, hydrophilicity, and open the channels up for improved water transport. Although many nanoparticulate with various properties and functionalities have been used for the same aims, the efforts have been made to choose the best nanomaterial and its loading among these five famous nanofillers for modifying PES ultrafiltration membrane. The nanocomposite membranes showed better antifouling characteristics and water permeability as compared with the pristine PES membrane because of the porosity and hydrophilicity improvements. However, further increasing nanoparticulate loading led to a possible agglomeration and diminished the water flux and fouling resistance. The effect of polymer concentration and solvent showed that membranes fabricated using 15 wt% of PES concentration possessed greater fouling resistance and water flux compared to those of fabricated using 18 wt% of PES concentration. Also, membranes fabricated using DMAc exhibited a more porous structure with considerably greater water flux as compared with those of fabricated using NMP as the solvent. Based on the results, 1 wt% of TiO 2 is recommended as the best nanoparticulate for the PES ultrafiltration membrane modification since it exhibited the superlative performance with a 320% water flux enhancement, nearly 98% BSA rejection, and 130% FRR improvement.
Desalination, 2011
Amine functionalized Multi-walled carbon nanotubes (F-MWCNTs)/polyethersulfone (PES) membranes were prepared using phase inversion induced by immersion precipitation. Crude MWCNTs were chemically treated using strong acids (H 2 SO 4 /HNO 3 ) and 1,3-phenylenediamine (mPDA) to produce the functional amine groups (\NH 2 ) on their surfaces. F-MWCNTs with different concentration were blended in the casting solution containing PES, polyvinylpyrrolidone (PVP) and dimethylacetamide (DMAC). Pure water was used as non-solvent. The FTIR spectra indicated that the amine functional groups were produced on the surface of MWCNTs. The membranes prepared with different concentrations of F-MWCNTs were characterized using contact angle, field emission scanning electron microscopy (FESEM), scanning electron microscopy (SEM), atomic force microscopy (AFM) and permeation tests. The surface hydrophilicity of membranes was significantly improved by addition of F-MWCNTs in the casting solution. An increment in the porosity, pore size and surface roughness of the membranes was observed by increasing F-MWCNTs content up to 1 wt.%. Further addition of F-MWCNTs caused a reduction in porosity and roughness of formed membrane. The membranes prepared with 0.5 and 1 wt.% of F-MWCNTs showed higher performance than neat membrane. Addition of F-MWCNTs in the casting solution improved the BSA rejection and antifouling properties of PES membrane.