Fabrication and characterisation of novel nanofiltration polymeric membrane (original) (raw)
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Preparation and Characterization of Nanofiltration Membrane for Water Treatment
2012
Thin-film composite (TFC) nanofiltration (NF) membranes were developed by terephthaloyl chloride (TPC) crosslinked the hydroxyl ended groups of hyperbranched polyester (HPE) on polyacrylonitrile (PAN) support. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) indicated that a thin layer of crosslinked HPE molecules were deposited on PAN porous membrane surface successfully. The preparation conditions were also optimized. The separation performance of PAN-HPE-TPC NF membranes are mainly related with the concentration of monomer in the aqueous phase rather than that in the organic phase. Water permeability and salts rejections of the membranes were measured. The flux and rejection of these NF membranes for Na 2 SO 4 (1 g/L) reached 11.43 L/m 2 h and 96.5% under 0.6 MPa, respectively. At the same time, the nanofiltration properties were compared with other membranes prepared with hyperbranched polymers. All NF membranes prepared with hyperbranched polymers showed relative high permeate flux.
Journal of Membrane Science, 2011
A novel TFC NF membrane was prepared on a polyacrylonitrile (PAN) supporting film using interfacial polymerization with the 3,3 ,5,5 -biphenyl tetraacyl chloride (mm-BTEC) monomer and piperazine (PIP). In the interfacial polymerization process, organic solvents were changed from cyclohexane to toluene, which increased the diffusion rate and solubility of PIP in the organic solvent. The diffusion of PIP and its solubility both influence the structure, morphology and thickness of TFC membranes. The streaming potential of TFC NF membranes was measured at various pHs. The results demonstrate that the surface of the membrane is positive charged. Permeation experiments were employed to evaluate the salt rejection and water flux performance of the membranes. These new NF films exhibited interesting performance properties as compared with commercial nanofiltration membranes in terms of their retention and relative flux for positively charged inorganic compounds. The salt rejection of the mm-BTEC/PIP membranes corresponding to different types of feed solutions are CaCl 2 > MgCl 2 > NaCl > Na 2 SO 4 . The flux and rejection of CaCl 2 (500 ppm) were 50.8 L/m 2 h and 95.1%, respectively, under 0.4 Mpa. In addition, the NF membranes exhibited enhanced water permeability and salt rejection compared with those prepared from trimesoyl chloride (TMC).
Preparation of nanofiltration membranes from polyacrylonitrile ultrafiltration membranes
Journal of Membrane Science, 2006
Polyacrylonitrile (PAN) membranes display some unusual features for ultrafiltration (UF). The meso-macropores of PAN UF membranes can be easily reduced into the range of micro-mesopores by taking advantage of surface tension forces within the capillary pores during heat treatment in the presence of ZnCl 2 . Asymmetric PAN nanofiltration (NF) membranes with controlled highly dense pore surface functional groups were prepared by hydrolysis of the nitrile groups with NaOH. The combined effects of heat treatment and the presence of ZnCl 2 on the formation of nanofiltration membranes were investigated. In addition, membrane post-treatment with NaOH was studied.
Journal of Membrane Science, 2016
Polyethyleneimine (PEI) is cheap low-toxic polymer and is used for the preparation of thin film composite (TFC) nanofiltration (NF) membranes. Nevertheless, one serious problem with most of the reported high salt rejecting (ca. 90% divalent cation) PEI-based TFC membrane is the low permeate flux and low average monovalent to divalent anion selectivity. There is also no comparative study of antifouling property of the PEI TFC membranes with conventional poly(piperazineamide) TFC membrane. Herein, we report an approach for in situ manipulation of permeation behavior and antifouling property of PEI-based TFC NF membrane. The approach was based on the use of dextran (Dex) conjugate of PEI (PEI-Dex) as a new monomer or co-monomer for the interfacial polymerization (IP) with trimesoyl chloride (TMC). Particularly, membranes prepared with mixture of PEI-Dex (2.5%, w/v)+PEI (0.25%, w/v) showed ca. 86 Lm-2 h-1 MPa-1 pure water permeate flux and 84%, 85% and 37% rejections of Na 2 SO 4, MgCl 2 and NaCl respectively. On the other hand, membrane prepared with PEI (0.25%, w/v) alone gave much lower permeate flux (37 Lm-2 h-1 MPa-1). The membrane prepared with PEI-Dex (3%, w/v) gave permeate flux as high as 163 Lm-2 h-1 MPa-1 with ca. 71%, 72% and 10% rejections of Na 2 SO 4, MgCl 2 and NaCl respectively under similar experimental conditions. All the PEI-based membranes prepared under suitable experimental conditions showed high average monovalent to divalent ions (cation and anion) selectivity. The active layer thickness decreased with increasing proportion of added PEI-Dex into the aqueous bath. This is the reason for the enhancement of permeate flux of the PEI-Dex membranes. On the other hand, low membrane surface charge at neutral feed pH is responsible for the higher average monovalent to divalent ions selectivity. The PEI-based membranes exhibited much improved antifouling/antiscaling properties compared to that of conventional poly(piperazineamide) TFC NF membranes. These types of membranes are suitable for long-term water softening without frequent cleaning step.
Fabrication of Nanofiber Filtration Membranes Using Polyethylene Terephthalate (PET): A Review
Journal of Membrane Science & Technology
Application of Polyethylene Terephthalate (PET) in membrane technology for fabrication of nanofiber filtration membranes for water treatment has gained increasing attention in recent years. Some new studies focusing on the application of recycled PET nanofibers in membrane structure have also been reported. Currently, many different chemical and physical methods are being used for water purification. However, membrane technology is becoming more popular and desirable in both domestic and industrial applications. This mini review paper aims to summarize (i) recent developments in synthesis of nanofiltration membranes using PET nanofibers, (ii) some of their different applications for water treatments, and also (iii) survey a new method in membrane fabrication technology for the first time using electrospining technique coupled by Vortex Fluidic Device (VFD) as a new platform for the better membrane fabrication process.
Journal of Environmental Management, 2020
This work investigates the performance and structure of polyamide thin film nanocomposite (PA-TFN) membrane incorporated with triethylenetetramine-modified graphene oxide (GO-TETA). The embedment of GO-TETA nanosheets within the structure of PA-TFN membrane was evaluated at different concentrations (0.005, 0.01, 0.03 wt%; in aqueous piperazine (PIP)) through interfacial polymerization (IP). The physicochemical properties of the prepared membrane were investigated by SEM, AFM, water contact angle, and zeta potential as well as ATR-IR spectroscopy. The presence of longer chains of amino groups (in comparison with the directly linked amino ones) among the stacked GO nanosheets was assumed to increase interlayer spacing, resulting in remarkable changes in water permeance and separation behavior of modified polyamide (PA) membrane. It is seen that GO-TETA nanosheets were uniformly distributed in the matrix of PA layer. With increasing the concentration of GO-TETA, the flux of TFN membranes under 6 bar was increased from 49.8 l/m 2 h (no additive) to 73.2 l/m 2 h (TFN comprising 0.03 wt% GO-TETA. In addition, more loading GO-TETA resulted in a significant decrease in the average thickness of the polyamide layer from ~380 to ~150 nm. Furthermore, addition of GO-TETA improved the hydrophilicity of nanocomposite membranes, resulting in superb water flux recovery (antifouling indicator) as high as 95% after filtration of bovine serum albumin solution. Also, the retention capability of the TFN membranes towards some textile dyes increased as high as 99.6%.
Pore-filled nanofiltration membranes based on poly(2-acrylamido-2-methylpropanesulfonic acid) gels
Journal of Membrane Science, 2005
Strong polyacid gel-filled membranes have been prepared by UV-initiated copolymerization of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and N,N -methylenebisacrylamide within the pores of a microporous polypropylene (PP) substrate. These poly(2-acrylamido-2methylpropanesulfonic acid) (PAMPS) gel-filled membranes were readily prepared with predictable amounts of the incorporated gel polymer (mass gain, MG) provided that threshold values of the degree of cross-linking and monomer concentration were exceeded. Most of the membranes showed large dimensional changes, particularly in their thickness on incorporation of the PAMPS. These changes were related to the amount of PAMPS incorporated into the membranes. In order to determine the polymer volume fractions of the incorporated gels, the partial specific volume of PAMPS (0.575 cm 3 /g) was obtained from density measurements using pycnometry. As a result of increase in thickness (volume) of the membranes, the polymer volume fractions of the PAMPS pore-filling gels were limited to values between 0.01 and 0.06, relatively low values compared to values achieved with other gel-filled membranes based on the same substrate. The Darcy permeability of PAMPS gel-filled membranes exhibits a typical relationship with polymer volume fraction, but the absolute values obtained are much lower than those of other gel-filled membranes previously studied. The lower permeability could be attributed to tightly bound water molecules along polymer chains, which effectively enlarges the hydrodynamic size of polymer chains and narrows the channels for water transport. Using the sphere model based on the Odijk's theory of semidilute polyelectrolyte solutions, the Darcy permeability of PAMPS gel-filled membranes could be calculated with good precision.
Journal of Applied Polymer Science, 2019
Hollow-fiber (HF) membranes have the advantage of a higher packing density compared to flat-sheet and spiral-wound configurations. However, the low pressure tolerance of HF membranes limits their applications in nanofiltration (NF). In this study, reinforced thin-film composite (r-TFC) HF NF membranes were fabricated and evaluated in tests with water containing different salts and organic matter. Reinforced polysulfone ultrafiltration membranes were used as a support for a polyamide layer prepared from piperazine and trimesoyl chloride monomers. The interfacial polymerization conditions were optimized via selection of the trimesoyl chloride reaction time that gave the highest membrane performance. A specific permeate flux of 5.1 L m-2 h-1 bar-1 , an MgSO 4 rejection of 69%, and an NaCl rejection of 26% at a transmembrane pressure of 6 bars were obtained with the optimized r-TFC membranes. Performance studies with water characterized by synthetic solution demonstrated removals of the total organic carbon, ultraviolet absorbance at 254 nm, and turbidity in excess of 65, 80, and 90%, respectively. The results of this study illustrate the feasibility of manufacturing r-TFC HFs and using them in water-treatment applications.