ORIGINAL ARTICLES Polysulfone/Polyvinyl alcohol thin film nano-composite membranes: synthesis, characterization and application for desalination of saline groundwater (original) (raw)
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The aim of the present work is synthesis, characterization and performance evaluation of modified Polysulfone/ polyvinyl alcohol (PS/PVA) thin film composite (TFC) membranes. The modification was carried out for PS support layer and/or crosslinked PVA barrier layer using titanium dioxide (TiO2) nanoparticles. Gultaraldehyde (GA) was used as a cross-linker of PVA. The synthesized thin film composite (TFC) or thin film nanocomposite (TFNC) membranes were characterized by measuring the contact angle, ATR-FTIR spectroscopy and scanning electron microscopy (SEM). The membranes performance included permeate flux (L.m-2.hr-1) and salt rejection (%) was evaluated as a function of synthesis and operation conditions. The obtained results showed that the membranes prepared from PS coated with TiO2 (o.25 wt. %) for 30 min immersing time, 0.1wt. % PVA crosslinked with GA solution concentration of (3% wt. %) and cured at a temperature of 75±2°C for 60 min gave the optimum performance. Also, the modification of PS-PVA/TFC membranes using TiO2 nanoparticles improved permeate flux from 9.32 to 11.56 (L.m-2.hr-1) with a slight increase in salt rejection from 76.79 to 78%. The salt rejection percent increased with increasing the cross-linker concentration, curing time and temperature as well as applied pressure and decreased with the feed concentration and vice versa in case of permeate flux for such factors except applied pressure. The desalination of two groundwater samples (brackish and saline) were performed using the best synthesized TFNC membrane to study the behavior of hypothetical salts during the desalination process.
Arabian Journal of Chemistry, 2020
A Polysulfone-Polyethylene glycol (PS/PEG) flat sheet membrane was prepared by phase inversion technique. Dimethyl Formamide (DMF) was utilized as a solvent and deionized water was utilized as the coagulant. Polyethylene glycol (PEG) of a various dose of PEG 2000 was utilized as the polymeric improvers and as a pore-forming agent in the casting mixture. The single-walled carbon nanotube (SWCNTs), multi-walled carbon nanotube (MWCNTs), aluminum oxide (Al 2 O 3) and copper oxide (CuO) nanoparticles (NPs) were utilized to improve the PS/PEG membrane performances. The characterizations of the neat PS, PS/PEG, PS/PEG/Al2O3 (M1) PS-PEG/CuO (M2), PS-PEG/SWCNTs (M3) and PS/PEG/MWCNTs (M14) nanocomposite (NC) modified membranes were acquired via Fourier-transform infrared analysis (FTIR), water contact angle estimation (WCA), scanning electron microscope (SEM), dynamic mechanical analyzer (DMA) and thermogravimetric analysis (TGA). Enhanced Direct contact membrane distillation (EDCMD) unit was used for estimating the efficiency of the performance of the synthesized NC membranes via 60°C feed synthetic water and/or saline oil field produced water samples containing salinities 123,14 mg/L. Adjusting the operational procedures and water characteristics confirmed a high salt rejection of 99.99% by the synthesized NC membranes. The maximum permeate flux
The thin film zeolite nanocomposite (TFNC) membranes were coated via interfacial polymerization of trimesoyl chloride (TMC) and m-phenylenediamine (MPD) monomers over porous polysulfone support. Different types of nanocomposite membranes were synthesized depending zeolite loading into the polyamide film. X-ray diffraction (XRD), FT-IR, transmission electron microscopy (TEM) and scanning electron microscopy techniques were employed to study the morphology of the pure zeolite and nanocomposite membranes. The calculated grain size of zeolite nanoparticles was 5.32 to 11.57 nm. The nanocomposite membranes had higher water permeability than the pure polyamide membranes. The results showed that addition of zeolite to the polyamide membrane led to improvement of surface properties such as an increase in pore size and water flux. The nanocomposite membranes with high concentration of monomers in interfacial polymerization exhibited a high water flux and low salt rejection. Excellent membrane performance was observed for the nanocomposite membrane containing about 0.05 % (w/v) zeolite, 0.15 % (w/v) TMC and 2 % (w/v) MPD which its flux was higher by 1.45 times than the flux value of the polyamide membrane with slightly decreasing in salt rejection. The obtained results show that TFZNC membranes are suitable for groundwater desalination.
Desalination, 2017
Thin film composite membranes (TFC) consisting of an ultra-thin polyamide layer made from interfacial polymerization remain to be of paramount importance for seawater desalination. Incorporation of nanoparticles into the polyamide layer has produced thin film nanocomposite (TFN) membranes with better performance than traditional TFC membranes. However, challenges of defect formation with the introduction of nanoparticles need careful adjustments in order to surpass the trade-off relationship between permeability and selectivity. Here, we explored the influential effects of nanoparticles, solvent and surfactant treatments on the desalination performance of TFN membranes under 55 bar using 35,000 ppm NaCl as the feed at 25°C. TFN membranes with various loadings of polyhedral oligomeric silsesquioxane (POSS) and TiO 2-SiO 2 core-shell nanoparticles were fabricated. Surfactant treatment was performed in two different ways: membrane soaking and in-tank addition. Unexpectedly, the latter endows the membrane with an improved rejection without sacrificing its flux possibly due to the formation of a surfactant monolayer to heal defects in TFN membranes. The newly developed TFN-T membrane with the aid of synergic effects from nanoparticles, ethanol and surfactant post-treatments shows comparable performance to most commercial membranes. This work may provide useful insights to overcome the trade-off relationship between permeability and selectivity of TFN membranes for seawater desalination.
Water Science & Technology, 2010
Composite nanofiltration (NF) membrane was developed polyacrylic acid (PAA) in situ UV graft polymerization process using ultrafiltration (UF) polysulfone (PSF) membrane as porous support. FT-IR spectra indicated that grafting was performed and it show peaks at 1,732 cm−1 and 3,396 cm−1 region for CO and OH starching bond of acrylic acid (AA) monomer, respectively. AFM microscopy showed the roughness of surface was reduced by increase of UV irradiation times. Effect of irradiation time on the grafting of acrylic acid (AA) in the same concentration was discussed. The salts rejection increase was accompanied with grafting of polysulfone (PSF) ultrafiltration (UF) membrane. The rejection of Na2SO4, MgSO4, NaCl and CaCl2 salts by PSF-grafted-PAA nanofiltration (NF) membrane was in 98, 60, 52 and 30% respectively, under 0.3 MPa.
Forward osmosis (FO) is a promising alternative to reverse osmosis (RO) in membrane-based water desalination. In the current study, carboxylated multiwalled carbon nanotubes (MWCNTs) were incorporated in a polyamide (PA) layer formed on top of a polysulfone porous support, resulting in a thin film nanocomposite (TFN) membrane. The amount of MWCNTs was varied (0.01, 0.05, 0.1, and 0.2 wt/vol %). The FO performance was investigated using deionized water as the feed solution and 2 M NaCl as the draw solution. It was found that the carboxylated MWCNTs enhanced the membrane hydrophilicity, surface roughness, and porosity. Such combined effects are believed to have led to enhanced FO water flux. TFN 0.2 showed the highest FO water flux of 73.15 L/m 2 h, an improvement of 67% compared to the blank thin-film composite (TFC) membrane and significantly better than the values reported in the literature. Direct observation by transmission electron microscopy revealed the presence of some open-ended CNTs favorably oriented across the PA layer. Those are believed to have facilitated the transport of water through their inner cores and contributed to the increase in water flux. However, this was at the expense of salt rejection and reverse solute flux performance. The best performing membrane was found to be TFN 0.01. It exhibited a salt rejection of 90.1% with a FO water flux of 50.23 L/m 2 h, which is 13% higher than the TFC membrane, and a reverse solute flux of 2.76 g/m 2 h, which is 21% lower than the TFC membrane. This TFN 0.01 membrane also outperformed the TFN membranes reported in the literature.
2019
In this work, we investigate the effect of varying the concentration of sodium chloride up to 70 g.L-1-equivalent to a recovery of approximately 50% in seawater desalination-on the transport properties of different reverse osmosis membranes. The study was performed using five commercial thin film composite (TFC) membranes and an analogue TFC membrane fabricated via the interfacial reaction of m-phenylenediamine and trimesoyl chloride. The surface properties of the membranes as measured by atomic force microscopy (AFM), zeta potential, and X-ray photoelectron spectroscopy (XPS) are presented. The solution diffusion model coupled with film theory was used to calculate the permeance of water and salt through the membranes, to account for the effect of concentration polarisation. The mass transfer coefficient in the test cells was estimated independently using the dissolution rate of benzoic acid; and was found to be approximately 1 × 10 −4 í µí±. í µí± −1. A linear reduction in salt permeance was observed in some of the RO membranes, while it remained constant for other membranes, including the analogue membrane. All the tested membranes maintained constant water permeance below 45 g.L-1 NaCl. However, when the salt concentration at the membrane surface exceeded 45 g.L-1 , water permeance either increased, remained constant or decreased. The results demonstrate the dependence of water and salt transport on the concentration of sodium chloride at the membrane surface. 1. Introduction Thin film composite (TFC) membranes formed via the interfacial polymerisation of m-phenylenediamine (MPD) and trimesoyl chloride (TMC) on a polysulfone or polyethersulfone ultrafiltration support are the most widely used membranes in water treatment and desalination. This is due to the reliability and relatively low-cost of the interfacial polymerisation technique in producing membranes with excellent separation properties and a wide variety of surface properties [1]. This enables the utilisation of TFCs in reverse osmosis water desalination systems with feed solutions ranging from low-salinity fresh and brackish water (~2-10 g.L-1 NaCl) to high-salinity seawater (~35 g.L-1 NaCl). Since, it is common to operate RO plants with overall recoveries around 50% [2], the membrane elements in a seawater reverse osmosis (SWRO) plant are subjected to salt concentrations in the feed between 35 to 70 g.L-1 from the entry point until the solution exits the RO spiral wound elements.
The possibility of producing drinking water from brackish, saline groundwater and sea water samples collected from Quseir city, Red Sea, Egypt using Lab prepared thin film composite (TFC) membrane was studied. The obtained results showed that the total dissolved solids (TDS) decreased from 2971.68 to 362.1 mg/l, 9062.53 to 591.79 mg/l and from 44703.58 to 5730.9 mg/l, in brackish, saline and sea water samples, with salt rejection percent of 87.81, 93.47 and 87.18 % and water flux of 27.77, 94.44 and 33.33 L/m 2 .h at 20, 35 and 40 bars, respectively. The effect of applied pressure and feed concentration on both water flux and salt rejection of membrane was also considered. The cations and anions rejection (R s %) showed that the divalent cations and anions are more rejected than the monovalent ones. The desalted water produced from desalination process of brackish and saline groundwater samples in one stage of operation is acceptable for drinking according to WHO and Egyptian guidelines. So, we can conclude that the membranes prepared at our Labs are more preferable for brackish water desalination.