Water Resources Management VIII 245 Reverse osmosis membrane modified by interfacial polymerization in non-polar heptane solvent assistance with acetone as a co-solvent (original) (raw)
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Water Resources Management VIII, 2015
The present work is focused on developing a suitable chemical membrane with polyamide, incorporating co-solvents. There are many benefits of using a membrane technique. It is cost-effective and can be fabricated easily and its materials have less effect on the environment. Therefore, the general membrane techniques have been used for the desalination of ocean water as a worldwide strategy to meet the demand for clean water. But in some cases the use of this membrane becomes limited when pore size, distribution of pores and low selectivity for pollutants/contaminants are considered. The fabrication of such a membrane with co-solvents is expected to lead to a solution to address some of these problems. In this study, a polyamide thin-film composite membrane was developed by interfacial polymerization in non-polar heptane solvent, using acetone as a co-solvent medium. The modified membranes were characterized by different techniques. Scanning electron microscope and atomic force microscopy images showed a smooth membrane surface. Thermo-gravimetric analysis indicated that these developed membranes possessed high thermal stability. High contact angles were observed in the presence of acetone as a co-solvent in the polyamide membrane. Similarly, high fluxes were observed with low salt rejection ability.
The objective of this work was to develop a suitable and highly efficient reverse osmosis membrane incorporating a co-solvent system. A polyamide thin-film composite membrane has been prepared by interfacial polymerization in n-heptane using diethyl ether and ethyl acetate as co-solvents at various concentrations. Heptane has a molecule of larger C-C chain than that of traditionally used hexane. Heptane was selected in order to study its effect on the morphology of the prepared membrane as well as on salt rejection ability and flux volume. Heptane appeared to produce an improved morphology, salt rejection ability, and flux volume, compared to hexane. To the best of our knowledge, this is the first attempt to prepare and characterize TFC RO membrane in n-heptane mixed with co-solvent. The membranes were characterized using microscopy, spectroscopy, and contact angle measurement techniques. From surface spectroscopic analyses, the addition of co-solvents led to a decrease in the roughness properties of the membranes. The synthesized polyamide membranes consist of large and ordinal ridgeand-valley formations. The salt rejection and water permeate flux were well controlled by the categories and amounts of co-solvents that were added. Thermal gravimetric analysis results indicated that all of the membranes exhibited high thermal stability with degradation temperatures of about 481 ± 2˚C. The high stability of the membranes was attributed to the sulfonic groups on the polymer chains. The contact angle also increased with an increasing co-solvent concentration. The performance characteristics of the membranes were evaluated by measuring the flux and rejection of isopropyl alcohol, NaCl, and MgCl 2 solutions. The rate of flux was proportional to the co-solvent concentration (i.e. flux increases with an increasing concentration), whereas the salt rejection properties were constantly high. Membranes formed with diethyl ether showed the highest salt rejection. Based on these data, membranes prepared using diethyl ether or ethyl acetate as a co-solvent in a non-polar heptane medium performed efficiently and exhibited high salt rejection characteristics with large flux values. These membranes represent promising candidates for freshwater desalination and removal of organic impurities.
A variety of polyamide thin film composite (PA-TFC) membranes was synthesized via interfacial polymerization (IP) technique. IP was carried out between aqueous solution of m-phenylene diamine (MPD) and trimesoyl chloride (TMC) in dodecane as organic solvent onto polysulfone (PSf) supporting membrane. The characterization of synthesized membranes was conducted using attenuated total reflection Fouier transform infrared spectroscopy (ATR-FTIR), scanning electron microscope (SEM) and contact angle measurement. Reverse osmosis performance included permeate flux (L/m2.hr) and salt rejection (%) was evaluated as a function of the synthesis conditions to investigate the optimum conditions that give the best performance membrane. The optimum conditions of synthesized membranes included MPD (1.5 wt.%) for 5 min. soaking time, TMC (0.05 wt. %) in dodecane for 30 sec. reaction time. The best synthesized membrane exhibited high salt rejection (99.81%) with high permeate flux (36.15 L/m2.h). Also, the concentration polarization modulus (M) and the true salt rejection (%) were measured using pure water with different salinities up to ≈ 10000 ppm NaCl feed solution. The obtained results showed that the concentration polarization modulus (M) ranged from 1.06 to 1.29 according to the salinity range.
Drinking Water Engineering and Science
The forward osmosis (FO) process has been considered for desalination as a competitive option with respect to the traditional reverse osmosis process. The interfacial polymerization (IP) reaction between two monomers (i.e., m-phenylenediamine, MPD, and 1,3,5-benzenetricarbonyl chloride, TMC) is typically used to prepare the selective polyamide layer that prevents salts and allows water molecules to pass. In this research, we investigated the effect of preparation conditions (MPD contact time, TMC reaction time, and addition of an amine salt) on the FO performance in terms of water flux and salt flux. The results showed that increasing MPD contact time resulted in a significant increase in the water flux and salt flux. However, increasing TMC reaction time caused a decline in both the water flux and the salt flux. The optimum condition that gave the highest water flux (64 L m −2 h −1) was found to be as 5 min for MPD and 1 min for TMC. The addition of an amine salt of camphorsulfonic acid-triethylamine (CSA-TEA) was able to have an apparent effect on the FO process by increasing the water flux (74.5 L m −2 h −1).
Development of novel thin film composite reverse osmosis membranes for desalination
PROCEEDINGS OF THE 2ND INTERNATIONAL CONFERENCE ON BIOSCIENCES AND MEDICAL ENGINEERING (ICBME2019): Towards innovative research and cross-disciplinary collaborations
Microporous Polyetherimide (PEI) membranes were prepared by wet phase inversion at different temperatures. The thin film composites (TFC) of polyamide on microporous PEI were prepared using meta-Phenylenediamine (MPD) and 1,3,5-Benzenetricarbonyl chloride (BTC). The ATR FTIR characterization showed the formation of polyamide (PA) on microporous PEI membrane, whereas scanning electron microscopy (SEM) revealed that a thin film of polyamide is formed on microporous PEI. The cross-sectional SEM of PEI prepared at 60 °C, showed finger like morphology and sparingly distributed balloon like morphology for PEI synthesized at 80 °C. The performance of PEI membranes and PA TFCs were ascertained by studying permeation of water and rejection of sodium chloride by reverse osmosis. The polyamide TFC with hydrophobic PEI support structures exhibited permeation of 28 to 50 lm-2h-1, with 98-95 % 2000 ppm NaCl rejection at 60 bar pressure.
Improved membrane structures for seawater desalination by studying the influence of sublayers
Desalination, 2012
This study describes the influence of polyethersulfone (PES) sublayers on the performance of polyamide (PA) reverse osmosis membranes. Asymmetric polymeric sublayers were synthesized by using the DIPS technique (Diffusion Induced Phase Separation). Sublayers are optimized mainly with respect to hydrophilicity, permeability and rejection potential by adjusting synthesis procedures. Parameters that were found to have an influence are the type of solvent (DMF and NMP were used), the air humidity, processing time, and concentrations of polymer. By carefully controlling these parameters, it was possible to prepare a range of sublayers with different characteristics, in the ultrafiltration-nanofiltration area. To visualize membrane surface characteristics, both scanning electron microscopy (SEM) and atomic force microscopy (AFM) measurements were performed. In addition, titanium (TiO 2 ) nanoparticles were assembled with polyethersulfone (PES) membranes at ultralow concentrations of nanoparticles to characterize TiO 2 /PES composite membranes and evaluate their permeate flux and solute rejection. Subsequently, a polyamide top layer was added by interfacial polymerization using typical reagents both in the aqueous and in the organic phase. The membrane performance was evaluated in terms of flux and salt rejection. Experimental design was performed in order to obtain the importance of some experimental variables during the polymerisation process. It was found that depending on the type of sublayer used in the procedure, a different membrane performance could be obtained.
Polyamide/polyacrylonitrile thin film composites as forward osmosis membranes
Thin film composites (TFCs) as forward osmosis (FO) membranes for seawater desalination application were prepared. For this purpose, polyacrylonitrile (PAN) as a moderately hydrophilic polymer was used to fabricate support membranes via nonsolvent-induced phase inversion. A selective thin polyamide (PA) film was then formed on the top of PAN membranes via interfa-cial polymerization reaction of m-phenylenediamine and trimesoyl chloride (TMC). The effects of PAN solution concentration, solvent mixture, and coagulation bath temperature on the morphology, water permeability, and FO performance of the membranes and composites were studied. Support membranes based on low PAN concentrations (7 wt %), NMP as solvent and low coagulation bath temperature (0 8C) demonstrated lower thickness, thinner skin layer, more porosity, and higher water permeability. Meanwhile, decreasing the PAN solution concentration lead to higher water permeance and flux and lower reverse salt flux, structural parameter, and tortuosity for the final TFCs. Composites made in N,N-dimethylformamide presented lower permeance and flux for water and salt and higher salt rejection, structural parameter, and tortuosity. FO assay of the composites showed lower water permeance values in saline medium comparing to pure water. V
Brazilian Journal of Chemical Engineering
Herein, the influence of pure and modified polyvinyl chloride (PVC) support layers on the performance of thin-film composite (TFC) membranes was investigated in water desalination. Accordingly, the PVC support was modified using (3-Aminopropyl) triethoxysilane (APTES) through bulk modification. The supports were synthesized at different doses of APTES (0-6 wt%) and characterized with various analytical techniques. The results showed that APTES affected considerably both the morphology and surface properties of the support layer. Afterwards, the polyamide (PA) layer was formed via an identical interfacial polymerization (IP). The separation experiments showed that modification of the support improved the performance of the TFC membranes, which stems from the improvement in the degree of cross-linking of the PVC structure. At an appropriate condition, permeate fluxes were 0.89 L.m-2 .h-1 .bar-1 and 2.70 L.m-2 .h-1 .bar-1 for TFC membranes with pure and modified PVC support layers, respectively. Interestingly, there were no significant changes in salt rejection of the prepared membranes.
Improved desalination by polyamide membranes containing hydrophilic glutamine and glycine
Water desalination and recycling of wastewater is a key challenge to meet water shortage issues. Thin film composite polyamide membranes are widely used for desalination; however, their low permeability due to a poor hydrophilicity is a major drawback. Here, we designed novel thin film composite membranes having good hydrophilicity, permeability, and stability without compromising solute rejection. We improved the membrane hydrophilicity by incorporation of hydrophilic additives, such as glycine and l-glutamine, into the polyamide layer. Hence polyamide-based flat sheet membranes were fabricated via interfacial polymerization of m-phenylenediamine and trimesoyl chloride and then were coated over a polysulfone/ sulfonated polyphenylsulfone (85:15) support. Polyamide membranes were then characterized and tested for desalination. Results show that the ridge and valley structure observed by scanning electron microscopy confirms the formation of the polyamide layer on membrane surface. The performance reached the highest pure water flux of 36.23 Lm −2 h −1 and flux recovery ratio of 89.18% for membranes with 2 wt% of l-glutamine. Incorporation of 2 wt% l-glutamine induced a high permeate flux and a maximum rejection of 87.87% for MgSO 4 , 83.50% for Na 2 SO 4 and 60.77% for NaCl solutions. Overall, the polyamide nanofiltration membrane with hydrophilic groups displayed superior antifouling property and can be used as a potential candidate for desalination.