Thin-film nanofiltration membrane with monomers of 1,2,4,5-benzene tetracarbonyl chloride and ethylene diamine on electrospun support: preparation,morphology and chlorine resistance properties

Polymer Bulletin - Novel polyimide nanofiltration membranes were prepared by interfacial polymerization using 1,2,4,5-benzene tetracarbonyl chloride (BTC) and trimesoyl chloride solution in...     

Synthesis of a novel sulfonated poly(amide‐imide) and its application in preparation of ultrafiltration PES membranes as a modifier

Sulfonated poly(amide‐imide) (SPAI) copolymer was synthesized, characterized, and blended into poly(ether sulfone) (PES)/dimethylacetamide casting solutions to prepare ultrafiltration membranes. Different weight ratios of the copolymer (0–10 wt %) were mixed in the PES casting solution. The analyses of contact angle and attenuated total reflection‐Fourier transform infrared spectra were used to study hydrophilicity and physicochemical properties of the membrane surface, respectively. The membranes were further characterized by scanning electron microscopy images, ultrafiltration performance, and fouling analyses. The outcomes showed that addition of the SPAI in the PES matrix improved considerably the membranes hydrophilicity. Moreover, with increasing SPAI concentration, the porosity, flux recovery ratio, and pure water permeability of the modified membranes were improved. The pure water flux was increased from 3.6 to 12.4 kg/m² h by increasing 2 wt % SPAI. The antifouling property of the modified PES membranes against bovine serum albumin, tested by a dead‐end filtration setup revealed that bovine serum albumin rejection of the obtained membrane was also enhanced and the antifouling properties of the blending membranes were improved. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46477.     

Effect of surface properties of polysulfone support on the performance of thin film composite polyamide reverse osmosis membranes

In this work, influence of initial conditions and surface characteristics of porous support layer on structure and performance of a thin film composite (TFC) polyamide reverse osmosis (RO) membrane was investigated. The phase inversion method was used for casting of polysulfone (PSf) supports and interfacial polymerization was used for coating of polyamide layer over the substrates. The effect of PSf concentrations that varied between 16 wt % and 21 wt %, and kind of the solvent (DMF and NMP) used for preparation of initial casting solution were investigated on the properties of the final RO membranes. SEM imaging, surface porosity, mean pore radius, and pure water flux analysis were applied for characterization of the supports. The substrate of the membrane, which synthesized with 18 wt % of PSf showed the most porosity and the synthesized RO membrane had the lowest salt rejection. In case of the solvents, the membranes synthesized with DMF presented better separation performance that can be attributed to their lower thickness and sponge‐like structure. The best composition of support for TFC RO membranes reached 16 wt % PSf in DMF solvent. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44444.     

A melamine-based covalent organic framework nanomaterial as a nanofiller in polyethersulfone mixed matrix membranes to improve separation and antifouling performance

This research reported developing a polyethersulfone (PES) membrane using covalent organic frameworks (COFs) nanoparticle with a mean dimension of 30 nm. The SNW-1 (Schiff-based network) COF was synthesized using precursors of melamine and terephthalic acid and then characterized by XRD, SEM, TEM, and FTIR analyses. The influence of different loadings of the COF was evaluated on the permeability, antifouling behavior and dye/salt rejection. The addition of SNW-1 caused a reduction in surface roughness and an improvement in hydrophilicity of the nanocomposite membranes, which improved their flux and fouling resistance considerably. The improvement of water flux, 2.6 times, was observed by adding 0.5 wt% COF to the membrane matrix. The 0.5 wt% COF membrane presented the best water permeability, 38.9 L/m² h bar BSA solution flux, dye rejection of 98.7% for Reactive Green 19 and 62.6% for Reactive yellow 39, 52.9% Na₂SO₄ and 24.5% NaCl salt rejections. Zeta potential and salt rejection trend indicated a negative surface charge on the nanocomposite membrane. Fouling experiments by BSA protein solution exhibited that the FRR reached 88.9% for 2 wt% COF membrane. Thus, employing SNW-1 into PES matrix resulted in a promising nanofiltration membrane for dye separation and moderate salt separation with suitable antifouling properties.     

Decolorization of C.I. Acid Blue 9 solution by UV/Nano-TiO(2), Fenton, Fenton-like, electro-Fenton and electrocoagulation processes: a comparative study

This study makes a comparison between UV/Nano-TiO(2), Fenton, Fenton-like, electro-Fenton (EF) and electrocoagulation (EC) treatment methods to investigate the removal of C.I. Acid Blue 9 (AB9), which was chosen as the model organic contaminant. Results indicated that the decolorization efficiency was in order of Fenton>EC>UV/Nano-TiO(2)>Fenton-like>EF. Desired concentrations of Fe(2+) and H(2)O(2) for the abatement of AB9 in the Fenton-based processes were found to be 10(-4)M and 2 x 10(-3) M, respectively. In the case of UV/Nano-TiO(2) process, we have studied the influence of the basic photocatalytic parameters such as the irradiation time, pH of the solution and amount of TiO(2) nanoparticles on the photocatalytic decolorization efficiency of AB9. Accordingly, it could be stated that the complete removal of color, after selecting desired operational parameters could be achieved in a relatively short time, about 25 min. Our results also revealed that the most effective decomposition of AB9 was observed with 150 mg/l of TiO(2) nanoparticles in acidic condition. The effect of operational parameters including current density, initial pH and time of electrolysis were studied in electrocoagulation process. The results indicated that for a solution of 20 mg/l AB9, almost 98% color were removed, when the pH was about 6, the time of electrolysis was 8 min and the current density was approximately 25 A/m(2) in electrocoagulation process.     

Synergistic effect of silica nanoparticles in the matrix of a poly(ethylene glycol) diacrylate coating layer for the surface modification of polyamide nanofiltration membranes

In this study, a commercial polyamide nanofiltration membrane was modified by a combination of poly(ethylene glycol) diacrylate (PEGDA) in situ polymerization and silica (SiO₂) nanoparticles. The PEGDA layer was polymerized on the surface of the membranes alone or mixed with SiO₂ nanoparticle. The surface modification influence on the water flux, salt rejection, and antifouling behavior was investigated. The effects of the nanoparticles and PEGDAylation on the membrane properties were characterized by Fourier transform infrared spectroscopy, contact angle measurement, and scanning electron microscopy analyses. The membranes that were in contact with 30 wt % PEGDA and then treated with ultraviolet light for 5 min had a better water flux than the unmodified membrane. The fouling resistance of the membranes to a foulant solution containing bovine serum albumin, humic acid, and sodium sulfate were studied, and the results show that the membrane with 30 wt % PEGDA had better antifouling properties. After the weight percentage of PEGDA for the prepolymerization solution was optimized (30 wt % was the best), the SiO₂ nanoparticle concentration in the prepolymerization matrix was optimized. The presence of SiO₂ nanoparticles in the PEGDA layer increased the membrane flux. The maximum water flux and good antifouling properties were obtained for 0.5 wt % SiO₂ nanoparticles in a 30 wt % PEGDA layer. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43793.     

Hydrophilic goethite nanoparticle as a novel antifouling agent in fabrication of nanocomposite polyethersulfone membrane

The goethite nanoparticle was used as a multifunctional additive to fabricate antifouling polyethersulfone (PES) nanofiltration membranes. The goethite/PES membranes were synthesized via the phase inversion method. The scanning electron microscopy (SEM) photographs showed an increase in pore size and porosity of the prepared membranes with blending of the goethite. The static water contact angle measurements confirmed a hydrophilic modification of the prepared membranes. With increase in the goethite content from 0 to 0.1 wt %, the pure water flux increased up to 12.7 kg/m² h. However, the water permeability decreased using high amount of this nanoparticle. Evaluation of the nanofiltration performance was performed using the retention of Direct Red 16. It was observed that the goethite/PES membranes have higher dye removal capacity (99% rejection) than those obtained from the unfilled PES (89%) and the commercial CSM NE 4040 NF membrane (92%). In addition, the goethite/PES blend membranes showed good selectivity and antifouling properties during long‐term nanofiltration experiments with a protein solution. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43592.     

Preparation and modification of thin film composite membrane using a bulky dianhydride monomer

One of the most effective methods to modify thin film composite (TFC) membranes is changing the chemistry of top selective layer by different monomers and different monomer concentrations. Herein, we report the preparation of modified TFC membranes using a pyromellitic dianhydride (PMDA) mixed with organic phase (trimesoyl chloride) and meta phenylene diamine (MPD). By manipulating the PMDA amount in organic phase, the structures and chemical compositions of polyamide selective layer could be modified. It was realized that the presence of PMDA could result in a modified membrane with higher surface roughness, less dense selective layer, more surface charge density, and better hydrophilic properties and consequently less fouling. The optimum PMDA concentration was found 0.05 wt%, such that the obtained membrane had 35.6 L m⁻² h⁻¹ pure water flux, about 1.6-fold higher than the reference membrane with similar salt rejection. Fouling intensity for the reference membrane was 38.1%, while for the modified membranes it decreased to 16.7%.     

Effect of titanium dioxide nanoparticles on polydimethylsiloxane/polyethersulfone composite membranes for gas separation

Introducing inorganic nanoparticles into the structure of polymeric membranes is an interesting approach for the enhancement of physical, chemical, and separation properties of the membranes. In this article, the performance of a two‐layer nanocomposite membrane for gas separation was studied. Three different methods for embedding titanium dioxide (TiO₂) nanoparticle were employed for the membrane preparation. The techniques include blending TiO₂ in the polydimethylsiloxane (PDMS) coating layer, blending TiO₂ in the polyethersulfone (PES) support and dip coating of PES support with TiO₂ accompanied by PDMS coating. The aim of the current research was finding the optimum technique for introducing TiO₂ into the membrane to obtain superior performance for gas separation. The results indicated that PES support containing TiO₂ nanoparticles possessed favorable effect on gas separation capability. The optimum performance was obtained by PDMS‐coated membranes prepared with 7 wt% TiO₂‐embedded PES support. Carbon dioxide (CO₂) permeance, CO₂/nitrogen, and CO₂/methane selectivity were obtained as 188.7 GPU, 8.6, and 3.4, respectively. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers