In situ manipulation of properties and performance of polyethyleneimine nanofiltration membranes by polyethylenimine-dextran conjugate (original) (raw)
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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).
Solvent resistant thin film composite nanofiltration membrane: Characterization and permeation study
Applied Surface Science, 2013
The present investigation reports the fabrication of thin film composite nanofiltration (TFC-NF) membranes using interfacial polymerization technique for desalination. Ethylene diamine (EDA) and terephthaloyl chloride (TPC) were employed as aqueous and organic phase monomers, respectively to develop polyamide thin layer on the surface of Celgard 2400. The prepared membranes were characterized through Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The molecular weight cutoff of TFC-NF membranes was estimated to be below 342 Da using dextrose, sucrose and raffinose solutions. A low cost dead end NF Cell was designed and manufactured domestically to conduct permeation experiments. The effect of different reaction conditions including concentration of monomers, residence time in each monomer and curing temperature on the membrane performance (water flux and MgCl 2 rejection) was also studied. The water flux was augmented linearly at higher applied pressure while MgCl 2 rejection was remained constant. The obtained water flux and MgCl 2 rejection were measured 33 L/m 2 h and 90%, respectively at 7 bar applied pressure. Beside this, membrane stability was analyzed, which confirmed the excellent constancy of ethanol and n-hexane fluxes even after an extended period. Hagen-Poiseuille equation was applied to estimate the TFC-NF membrane pore size ∼0.45 nm.
Journal of Nanoparticle Research, 2012
In this article, we describe the synthesis of new and ion-selective nanofiltration (NF) membranes using polyvinylidene fluoride (PVDF) nanofibers and hyperbranched polyethylenimine (PEI) as building blocks. These new nanofibrous composite (NFC) membranes consist of crosslinked hyperbranched PEI networks supported by PVDF nanofibrous scaffolds that are electrospun onto commercial PVDF microfiltration (MF) membranes. A major objective of our study was to fabricate positively charged NF membranes that can be operated at low pressure with high water flux and improved rejection for monovalent cations. To achieve this, we investigated the effects of crosslinker chemistry on membrane properties (morphology, composition, hydrophobicity, and zeta potential) and membrane performance (salt rejection and permeate flux) in aqueous solutions (2,000 mg/L) of four salts (NaCl, MgCl 2 , Na 2 SO 4 , and MgSO 4) at pH 4, 6, and 8. We found that an NFC-PVDF membrane with a network of PEI macromolecules crosslinked with trimesoyl chloride has a high water flux (*30 L m-2 h-1) and high rejections for MgCl 2 (*88 %) and NaCl (*65 %) at pH 6 using a pressure of 7 bar. The overall results of our study suggest that PVDF nanofibers and hyperbranched PEI are promising building blocks for the fabrication of high performance NF membranes for water purification.
Effect of pH on the performance of polyamide/polyacrylonitrile based thin film composite membranes
Journal of Membrane Science, 2011
Molecular weight cut off (MWCO) pH Nanofiltration (NF) Interfacial polymerization (IP) Thin film composite (TFC) Glucose Polyethylene glycol (PEG) Donnan steric partitioning pore model (DSPM) a b s t r a c t In this study the effect of pH on the performance of thin film composite (TFC) nanofiltration (NF) membranes has been investigated at the relevant pH conditions, in the range of pH 1-13. TFC polyamide NF membranes have been fabricated on a polyacrylonitrile support via interfacial polymerization between piperazine in an aqueous phase and trimesoyl chloride in an organic phase. Membrane characterization has revealed that the produced membranes show a NaCl retention similar to NF-270 and Desal-5DK, a permeance in between those of NF-270 and Desal-5DK, and a slightly higher iso-electric point than NF-270 and Desal-5DK. The molecular weight cut-off of the membranes appeared to be practically constant in acidic and neutral conditions. At extremely alkaline conditions (pH > 11) an increase in molecular weight cut-off and a reduction in membrane flux has been observed. According to the Donnan steric partitioning pore model (DSPM) the change in performance in alkaline conditions originates from a larger effective average pore size and a larger effective membrane thickness as compared to the other pH conditions.
Separation and Purification Technology, 2019
Two new sulfonated (SDA) and carboxylated (CDA) aromatic diamine-diol monomers were synthesized and applied to prepare thin-film composite (TFC) nanofiltration (NF) membranes with improved antifouling and performance properties. The interfacial polymerization method was used to make sulfonated and carboxylated TFC-NF membranes with reaction of trimesoyl chloride (TMC) in the organic phase with amine and hydroxyl agents in the aqueous phase. Herein, for the first time, a comparison between carboxylated and sulfonated TFC was carried out. Moreover, the probability of synergetic effect between these two synthetic monomers (CDA and SDA) and piperazine monomer was studied (the sulfonated monomer and piperazine showed a synergetic effect). The outcomes of flux recovery ratio (FRR), flux and contact angle showed that in the presence of newly synthesized monomers, membrane hydrophilicity considerably improved. The salt retention sequence for all membranes was Na 2 SO 4 ≫ NaCl > CaCl 2 , which means all membranes had a negative charge. Among the five prepared TFC membranes (SDA, CDA, PIP, SDA/PIP, and CDA/PIP), the SDA/PIP showed the best salt rejection (97% Na 2 SO 4) with flux (50 Lm −2 h −1) and 91% FRR, at operating pressure of 10 bars. Although the SDA showed the highest permeability (62 Lm −2 h −1) and FRR of 92%, it presented the lowest Na 2 SO 4 rejection. The results indicated that mixing carboxylated monomers with PIP caused deterioration in properties, while mixing sulfonated monomer with PIP enhanced the performances of the related TFC. Better permeability of the membrane made by newly synthesized monomers is ascribed to the existence of strong hydrophilic sulfonic acid, carboxylic acid and terminal hydroxyls, and amine groups at polyamide top layer producing enhanced membrane antifouling properties.
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.
Novel polyvinyl chloride grafted poly (ethylene imine), PVC-g-PEI membranes have been successfully synthesized by solvent evaporation technique using THF/ethanol as a solvent mixture. PEI was incorporated into PVC in different portions to increase the weak hydrophilicity of PVC membranes and to enhance physicochemical membranes surface properties. Membranes preparation conditions of PVC-g-PEI and their applications for water desalination process were optimized and discussed in details. PVC-g-PEI membranes were characterized by FTIR, morphologically using SEM, thermally using TGA&DSC, and mechanically using universal testing machine. Poly (ethylene glycol), PEG was then added to PVC-g-PEI membranes as a pore forming additive to increase pores density area and improve efficiency of the permeation flux of membranes. Addition of PEG portions increased permeation flux of PVC-g-PEI membranes (452 L/D/M 2 513 L/D/M 2 and605 L/D/M 2) and salt rejection performance for mono membrane (33.5%, 30.8%and 27.4 %) for 3%, 2% and 1% NaCl solutions, respectively. Ion Exchange Capacity (IEC) for (PVC-g-PEI) membrane was 2.3 meq/gm and water uptake was 23%.All filtration experiments results were carried out at a trans-membrane pressure of 0.3 MPa at room temperature. The results showed that the permeate quality and quantity almost stable upon long run, thus PVC-g-PEI membranes can be used effectively for water treatment applications e.g. Nano-filtration and desalination.
In continuation of work (J. Membr. Sci. 455, 2014, 271) for in situ PEGylation of thin film composite (TFC) membrane, herein, effect of polyethylene glycol (PEG) end-group on the properties and performance of PEGylated TFC nanofiltration (NF) membranes is reported. In situ PEGylation of conventional poly(piperazineamide) TFC NF membranes was performed by interfacial polymerization between TMC and PIP+PIP-terminated polyethylene glycol (PIP-PEG-PIP), PIP+m-phenylenediamine-terminated PEG (MPD-PEG-MPD) and PIP+alkyl amine terminated-PEG (H 2 N-PEG-NH 2 ) mixtures respectively. Among these three processes, PEGylated membranes prepared with TMC and PIP+PIP-PEG-PIP mixture exhibited excellent antifouling property, similar performance, close pore radius and pore structure 2 factor compared to conventional poly(piperazineamide) TFC NF membrane. This is attributed to the closer reactivity of PIP and PIP-PEG-PIP towards TMC. Membranes prepared with TMC and PIP+MPD-PEG-MPD mixtures exhibited superior antifouling property compared to conventional TFC NF membrane, nevertheless, rejection and permeate flux were decreased. TFC membranes prepared with PIP+H 2 N-PEG-NH 2 mixtures/TMC exhibited similar performance compared to conventional membrane with low degree of PEGylation and hence showed only marginal improvement of antifouling property.