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This study aimed to prepare antifouling and highly mechanical strengthening membranes for brackish and underground water desalination. It was prepared from cellulose acetate (CA) loaded anatase. Anatase was prepared from tetra-iso-propylorthotitanate and carboxymethyl cellulose. Different concentrations of anatase (0.2, 0.3, 0.5, 0.6, 0.7 and 0.8) % were loaded onto CA during the inversion phase preparation of the membranes. The prepared membranes were characterized using Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM & EDX), mechanical properties, swelling ratio, porosity determination, and ion release. The analysis confirmed the formation of anatase on surface and inside the macro-voids of the membrane. Furthermore, the loading of anatase improved the mechanical properties of the CA membrane and decreased its swelling and porosity rate. Also, CA-loaded anatase membranes displayed a significant antibacterial potential against Gram-positive and Gram-negative bacteria. It can be concluded that the prepared CA-loaded anatase membranes have high mechanical properties that are safe, economical, available, and can stop membrane biofouling.

This study provided a facile approach for the development of antifouling and antibacterial polyethersulfone (PES) composite film. Mainly, hyperbranched polyester-amide (PESAM) was used as both the reducing and capping agent for the in situ formation of AgNPs. The nanoparticles were intensively investigated using Fourier transform infrared spectroscopy (FTIR), ultra-violet spectroscopy (UV-vis), scanning and transmission electron microscopy (SEM & TEM) and X-ray diffraction (XRD). AgNPs were narrowly distributed with an average particle size of about 6 nm. PESAM was mixed with PES to realize free-standing film using the phase inversion method. The inclusion of PESAM in the composite film significantly improved hydrophilicity as confirmed by the contact angle measurements. Furthermore, SEM and EDX investigations confirmed that PESAM induced the in situ formation of AgNPs not only on the film surface but also inside its macro-voids. The composite film (PES/PESAM/Ag) displayed significant antibacterial potential against Gram positive and Gram negative bacteria. Overall, the described method paves the way towards development of advanced PES composite films with antimicrobial properties for broad application areas that include desalination membranes or active packaging materials.

Nowadays, polymers blending technique is used to prepare membranes to produce modified membranes in performance and characterization. A mathematical model for membrane preparation in a ternary and quaternary systems for blending between polyvinylchloride (PVC) and other polymers is presented in this chapter. An extended modified Flory–Huggins theory was applied as a source for the model of blend polymers. The diffusion model is studied to discuss the immersion/precipitation step during membrane formation. Most researches indicated that the solvent volume fraction increased during the coagulation time, while the polymer solution volume fraction reduced leading to solvent removal from polymer solution during membrane formation.

The present study describes the Facial preparation of bacterial-resistant cellulose acetate (CA) membranes by using novel non-toxic antibacterial cyanoacetyl microcrystalline cellulose (NACAMC). Different concentrations of (NACAMC) were blended with CA to prepare three antibacterial cellulosic membranes namely: M1, M2 and M3 having hindrance activity against tested strains. The Fourier-transformed infrared spectroscopy (FT-IR) was used to investigate the changes in chemical and physical membrane characteristics. The obtained membranes (M1, M2, and M3) were visually evaluated by scanning electron microscopy (SEM). M2 and M3are characterized by a pore-free upper surface and a porous bottom surface of the membranes in comparison with the CA blank membrane. The water uptake ratio was measured to be 175%, 426%and 707% for M1, M2and M3 respectively. Also, the average pore size distribution for prepared membranes was measured. The Mechanical properties of M1 and M2 were measured which indicates that the tensile strength and elongation are higher in M2 than M1. Antibacterial activity for membranes and (NACAMC) against 5 pathogenic strains were evaluated. These results could be developed for several uses as in wound dressing applications, food packaging, and water treatment antifouling membranes.

New formulations of cellulose acetate (CA) membrane with graphene (G)/graphene oxide (GO) are suggested and investigated in the present work. This study is intended to find a wide range of conditions for fabricating CA membranes in the presence of some additions of graphene (G), and graphene oxide (GO). The membrane is prepared by phase inversion process. Microscopic investigations for graphene (G), graphene oxide (GO), and prepared membrane were performed by high-resolution transmission electron microscope (HRTEM) and scanning electron microscopy (SEM). The mechanical properties of prepared membranes are determined and evaluated. Permeation tests were performed using natural seawater and simulated seawater to check the prepared membrane performance. The results presented that the permeate flux of M25% CA membranes containing 0.01 wt.% G is the highest flux (57–74 l/m2 h) compared with the neat CA membrane, and the 0.01 wt.% GO-based membranes, while the GO-based membranes were comparable as the neat CA membrane at operating pressures (30–35 bar) and with a feed of 35 g/l NaCl solution. The results showed a remarkable salt rejection of simulated seawater of 95%, and natural seawater with a feed from the Mediterranean Sea displayed 90% salt rejection and accepted pure water flux as well.

The effectiveness of woven and nonwoven polyester support and coagulation time during membrane formation on the performance and characterization of prepared membranes was studied. The blend membranes of polyvinylchloride with cellulose acetate were prepared by the immersion precipitation process. The prepared membranes were characterized using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectrophotometry and a mechanical test. Membrane performance was tested using a feed of different synthetic salt solutions. The results proved that the prepared membrane using woven support provided the highest permeate flux and good salt rejection (93.3%) for a salty solution concentration of 20,000 ppm. The stress-strain mechanical test indicated that the excellent mechanical behavior was shown for membranes prepared with a woven support, which has a strength of 12.6 N/cm2 with an elongation of 25 mm for M8. A fouling test was carried out using a mixture solution of salt and humic acid. Using the prepared membranes with woven support provided the best antifouling properties with a flux recovery of 99.2% compared with a flux recovery of 96% using the prepared membrane without support.

Multi-bore hollow fiber membranes were prepared through phase inversion spinning process using new locally designed spinnerets of various geometrical shapes. The spun cylindrical-like, rectangular or ribbon-like, and triangular-like are prepared, dried, and characterized by scanning electronic microscope. Fibers of circular (seven, five, and four bores) shape, rectangular of five bores, and triangular of three bores were chosen to study the effect of both geometrical configuration and the number of bores on the amorphous structure and the mechanical properties of the membranes. Membrane geometry, surface amorphous, and bore arrangements are very sensitive to the operating conditions, especially the extrusion and drawing rates. Three polymeric blends of different compositions are used to prepare multi-bore hollow fiber membranes. This study revealed that the blend composition of PES 16%, PVP 2%, PEG 2%, diethylene glycol 2%, and NMP 78% gives excellent mechanical properties. Optimization of the preparation conditions also developed, where the dope flow rate, the bore flow rate, and the air gap were 1.14 cm3 s−1, 1.1 cm3 s−1, and 0 cm, respectively. Furthermore, this study proved that the circular arrangement has high mechanical strength. The prepared seven-MBHF membranes were applied in the membrane distillation process, a solution of 35 g/l NaCl was used to test the membrane performance, and the achieved flux and rejection were 28.32 L/m2 h and 98.9%, respectively. This performance demonstrated that the prepared membrane in this way is suitable to compete with conventional reverse osmosis technology that uses single track hollow fibers.

Water Desalination is becoming an issue for saving the required potable and drinking water due to shrinkage of pure water. Thus, this work deals with antifouling membrane preparation using poly meric compounds of Polyethersulfone/ Polyvinylalcohol (PES/PVA) with nanomaterials to produce antifouling membrane for water desalination. The PES membrane has prepared by phase inversion process followed by different coating ways. The coating with PVA provided the highest hydrophilic surface. The characterization of prepared membranes was carried out using various analysis methods such as scanning electron microscopy (SEM), mechanical properties, porosity and contact angle. The pore size distribution of prepared membranes was determined using the Brunauer-Emmett-Teller (BET) method. The result showed that the best membrane performance was membrane which has a coating with PVA layer, where rejection reached to 99 %, 95% and 88% as a function of concentration 500, 1500, and 3000 ppm respectively, while the permeate flux reached to 48.4 L/m2.h, 32.3 L/m2.h and 21.5 L/m2.h as a function of concentration 500, 1500, and 3000 ppm respectively.

We propose a new membrane of cellulose acetate/graphene/Ag nanoparticles and/or Cu nanorods (CA/G/Ag–Cu) composite, which improved the membrane desalination and biofouling simultaneously using membrane technology. The membrane was prepared from casting polymer dope solution containing 25 wt.% in acetone as solvent with different concentrations of graphene dispersed on it Ag:Cu at 18 °C. The membrane was then characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and further tested for the separation of saline solutions (5 g/L and 10 g/L NaCl) by reverse osmosis system. The release of silver- and copper-nanoparticles from the membrane was monitored in a batch experiment by an atomic absorption spectrophotometer (AAS). The biofouling effects of addition G/nano-(Ag–Cu) on membrane performance were investigated against Gram +ve and Gram −ve bacterial test organisms. Membranes were assayed with an agar culture medium and by immersing in bacterial suspension. Bacterial activities were observed by inhibition zones formation and investigating biofilm formation by SEM. The reference membrane (without additions) had no antibacterial activity and bacterial growth was found on the membrane surfaces, while CA/G/nano-(Cu–Ag) membrane had shown antibacterial activity. Permeability tests showed a vast improvement of water flux and salt rejection.

In this work, new composite membranes were successfully prepared via phase inversion technique using polyvinyl chloride (PVC) and polyvinylpyrrolidone (PVP) as polymers and tetrahydrofuran (THF) and N -methyl-2-pyrrolidone (NMP) as solvents. The prepared membranes have been characterized by scanning electron microscope (SEM), and fourier transforms infrared spectroscopy (FTIR). The scanning electron microscope results prove that the prepared membranes are smooth and their pores are distributed throughout the whole surface and bulk body of the membrane without any visible cracks. The stress–strain mechanical test showed an excellent mechanical behavior enhanced by the presence of PVP in the prepared membranes. The membranes performance results showed that the salt rejection reached 98% with a high flux. This, in turn, makes the prepared membranes can be applied for sea and brackish water treatment through membrane distillation technology.

The pollution of water resources, severe climate changes, rapid population growth, increasing agricultural demands, and rapid industrialization insist the development of innovative technologies for generating potable water. Polyvinylchloride/cellulose acetate (PVC/CA) membranes were prepared using phase inversion technique for seawater reverse osmosis (SWRO). The membrane performance was investigated using Red Sea water (El-Ein El-Sokhna-Egypt). The membrane performance indicated that the prepared membranes were endowed to work under high pressure; increasing in feeding operating pressure led to increase permeate flux and rejection. Increasing feed operating pressure from zero to 40 bar led to increase in the salt rejection percent. Salt rejection percent reached to 99.99% at low feed concentration 5120 ppm and 99.95% for Red Sea water (38,528 ppm). The prepared membranes were characterized using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectrophotometry, and mechanical properties. SEM, FTIR and mechanical results were used to distinguish the best membrane for desalination. According to characterization results, one prepared membrane was selected to run performance test in desalination testing unit. The membrane (M3) showed excellent performance and stability under different operating conditions and during the durability test for 36 days.

Microfiltration/ultrafiltration (MF/UF) Adsorptive polyamide-6 (PA-6) membranes were prepared using wet phase inversion process. The prepared PA-6 membranes are characterized by scanning electron microscopy (SEM), porosity and swelling degree. In this study, the membranes performance has examined by adsorptive removal of copper ions from aqueous solutions in a batch adsorption mode. The PA-6/H2O membranes display sponge like and highly porous structures, with porosities of 41-73%. Under the conditions examined, the adsorption experiments have showed that the PA-6/H2O membranes had a good adsorption capacity (up to 120-280 mg/g at the initial copper ion concentration (C0) = 680 mg/L, pH7), fast adsorption rates and short adsorption equilibrium times (less than 1.5-2 hrs) for copper ions. The fast adsorption in this study may be attributed to the high porosities and large pore sizes of the PA-6/H2O membranes, which have facilitated the transport of copper ions to the adsorption. The results obtained from the study illustrated that the copper ions which have adsorbed on the polyamide membranes can be effectively desorbed in an Ethylene dinitrilotetra acetic acid Di sodium salt (Na2 EDTA) solution from initial concentration (up to 92% desorption efficiency) and the PA-6 membranes can be reused almost without loss of the adsorption capacity for copper ions. The results obtained from the study suggested that the PA-6/H2O membranes can be effectively applied for the adsorptive removal of copper ions from aqueous solutions.

A sulfonated hyperbranched polyester (HPES-SO3H) was synthesized in order to prepare a proton exchange membrane. The modified hyperbranched polymer was characterized using 1H and 13C NMR and GPC. Hybrids of the modified polymer and polyether sulfone were prepared to incorporate sufficient entanglements and hence increase the mechanical properties of HPES-SO3H. The morphology of the films cast from the hybrids was studied using scanning electron microscopy (SEM), which confirmed the presence of a smooth surface with a controlled pore size. In order to enhance the proton conductivity and improve the mechanical properties of the obtained membrane, different loadings of sodium titanate nanowires (ST NWs), prepared hydrothermally, were added as fillers for the polymer hybrids. Membranes cast from pure polymer hybrids or nanocomposites were used to fabricate a membrane electrode assembly (MEA). It was found that a membrane composed of hyperbranched polyester with a 50% degree of sulfonation and immersed in H2SO4 for 2 h, had an open circuit potential of 0.9 V, compared with Nafion® which showed a potential of 0.85 V. Increasing the immersion time in H2SO4 solution to 12 h led to a sharp increase in current density to a value of 200 mA cm−2 and a power density value of 35 mW cm−2. Moreover, the results reveal that the addition of different amounts of ceramic material to the polymer hybrids has a negative influence on the membrane performance. Nevertheless, high proton conductivity was noticed in samples containing 1 wt% ST NWs. The good water swelling and mechanical properties of the obtained sulfonated polymeric hybrids, along with their cell performance being comparable to commercial membranes, make them promising candidates as proton exchange membranes for fuel cells.

The aim of this paper is to design a water desalination plant using Reverse Osmosis membrane to treat salt water to be usable for drinkable, domestic, industrial or agricultural uses. RO unit is designed to conservative standards for versatility in the event of feed water quality variations. The design includes a feed water flush cycle to minimize membrane fouling and piping corrosion during shutdown. The system will be all appropriate controls and instrumentation for automatic operation. All system components are available and of heavy duty industrial design and fabricated with the highest quality workmanship. Quality control will be maintained throughout all manufacturing processes. The system will produce permeate water minimum of 3600 m3/day with a quality of approximately 100 ppm total dissolved solids (TDS) when operating on well feed water with a 10,000 ppm TDS and a temperature of 25 - 30 degrees C. The design permeate recovery is 50%; and energy recovery device which saves $30,556.28/year.

The work aimed to prepare co-polyalkoxyether-imide (PEI) asymmetric membranes to appreciate high flux water selective polymeric membranes appropriate for the separation of organic molecules from aqueous mixtures by nanofiltration. These membranes were prepared under controlled experimental conditions from solvent non-solvent of N,N-dimethylformamide (DMF) – water (H2O) solutions with the corresponding polyamic acid (PAA); after the wet phase inversion in a water bath, the PAA membranes were imidized by thermal treatment. The membrane physical properties, recorded by SEM, were used to optimize the asymmetric membrane preparation to improve the separation properties by tuning the thickness of the dense top layer. The performances of nanofiltration separations were examined in the light of the influence of sets of parameters. The flux of asymmetric PEI membranes increased with an increase of applied pressure. Additional, the permeate flux and membrane permeance for pure water is better than the aqueous organic solutions. Thus, the aqueous organic solution has an influence on decreasing the flux and membrane permeance. PEI membranes showed high rejection for hydrophilic molecules, like polyethylene glycol, with molecular weight ranging from 400 to 6000 Dalton; according to molecular weight, organic rejection of 79–100% were achieved from 500 ppm aqueous solutions of organic compounds.

Cellulose acetate (CA)/carbon nano tubes (CNT) membranes were prepared using phase inversion method by dispersing different ratio of carbon nano-materials in CA casting solution. Different polymer to solvent ratios examined for enhancement of membrane desalination. The influence of differentiation in CA and CNT ratio on the morphology and thermal stability were investigated using scanning electron microscopy and thermogravimetric analysis (TGA). Also, Permeation performance of the prepared membranes was evaluated. Morphology results showed that CA membrane porosity decreased with increasing polymer ratio. The membranes pure water flux was increased by the addition of nano-carbon materials. The optimum polymer to solvent ratio for accepted desalination performance was 25:75. The presence of carbon nanotubes (CNT) in the optimum membrane enhanced the salt rejection markedly to 96% as well as the pure water flux has been improved. The optimum membrane in the presence of CNT has convenient thermal stability with accepted water content percent and swelling percent.

Membrane distillation (MD) is a thermal, vapor-driven transportation process through micro porous hydrophobic membranes that is increasingly being applied to seawater and brine desalination processes. Two types of hydrophobic microporous polyethersulfone flat sheet membranes, namely, annealed polyethersulfone and a polyethersulfone/tetraethoxysilane (PES/TEOS) blend were prepared by a phase inversion process. The membranes were characterized and their performances were investigated using the vacuum membrane distillation of an aqueous NaCl solution. The performances of the prepared membranes were also compared with two commercially available hydrophobic membranes, polytetrafluorethylene and polyvinylidene fluoride. The influence of operational parameters such as feed temperature (25–65 °C), permeate vacuum pressure (200–800 mbar), feed flow rate (8–22 mL/s) and feed salt concentration (3000 to 35000 mg/L) on the MD permeation flux were investigated for the four membranes. The hydrophobic PES/TEOS membrane had the highest salt rejection (99.7%) and permeate flux (86 kg/(m2·h)) at 65 °C, with a feed of 7000 ppm and a pressure of 200 mbar. Open image in new window

This article deals with “developing novel polyamide-6/chitosan membranes for water desalting using wet phase inversion technique”, in which novel polyamide-6/chitosan membranes were prepared using an appropriate polymer concerning the national circumferences, along with the definition of different controlling parameters of the preparing processes and their effects on the characteristics of the produced membranes. Further, evaluation process of the fabricated sheets was undertaken. Preparation process was followed by assessment of the membrane structural characteristics; then the desalting performance of each prepared membrane was evaluated under different operating conditions in order to find the structure–property relationship. The results show that the membrane flux increases with the increase of operating pressure. The salt rejection and permeation flux have been enhanced this indicates that the chitosan (CS) addition to the polyamide-6 (PA-6) membrane increases the membrane hydrophilic property. Hydraulic permeability coefficient is not stable and varies considerably with the operating pressure.

This article presents the results concerning the preparation of asymmetric polyamide-6 (PA-6) membrane using the wet phase inversion technique. The membrane was prepared from a casting dope containing 20 wt.% of PA-6 in formic acid at 18°C. The membrane was then characterized by scanning electron microscopy and further tested for the separation of methanol/methyl acetate solutions by pervaporation. The effects of feed methanol concentration, operating temperature and the feed liquid flow rate on the membrane performance were investigated. The permeation flux increased with increasing feed methanol concentration, feed temperature, and feed flow rate. Some typical data of separation factor were: at the operating temperature of 40°C, feed 80% methanol/20% methyl acetate and the feed liquid flow rate of 16.5, 20.6 mL/s, the separation factor was 50 and 83 respectively.

Thermodynamic behavior of a ternary system with one low molecular weight component, formic acid (FA) as the solvent, water (non-solvent), and two high molecular weight polymers [polyamide-6 (PA-6) and cellulose acetate (CA)] was investigated using an extended modified Flory-Huggins model. Where, all chemicals were purchased from Leuna Werke AG (Germany). The model was solved by MATLAB SIMULINK software manufactured in the USA. The predicted results from the model explained that the miscibility of the two blend polymers, PA-6 and CA, completed over all compositions at room temperature, and the minimum point where the miscibility of the two polymers completed was in the composition of 0.2 volume fraction of PA-6 at Gibbs free energy change on mixing (ΔGm) of -1.74015 kJ/mole. The critical temperature (Tc) for superiority properties of the polymer blend solution are in the range between the upper critical saturation temperature (UCST) 323K and the lower critical saturation temperature (LCST) 338K. The diffusion model on the solution of the immersion precipitation process in the coagulation bath indicates that the solvent volume fractions increase with time, while the polymer solution volume fraction decreases, due to solvent removal from the polymer solution and membrane formation. According to the mathematical model, it was found that the annealing temperature can affect the densification of the membrane top layer. However, the heat treatment process leads to a decrease in thickness of the membrane bottom layer, as a result of reduced and distributed membrane pores.

Nanocomposite vulcanizates comprising the poorly compatible acrylonitrile butadiene rubber/styrene butadiene rubber blend are homogenized with 20 parts per hundred montmorillonite forms showing various levels of amphiphathicity: slightly hydrophobic (Mont-25/50) and highly hydrophobic (Mont75/100) as compared to the highly hydrophilic pristine form (Mont-0). The purpose of the amphiphathicity is to afford simultaneous binding sites for the poorly compatible components. Thus maximum compatibility is reached with either Mont-75 or Mont-50 which improves the mechanical properties. Scanning electron microscopy corroborates cocontinuous morphology. Water vapor permeation through sheets/membranes fabricated from these compositions follows best performance with Mont-25 followed by Mont-50 while Mont-75 and Mont-100 based membranes acquire an organized continuous drop. This highlights the role of organophilicity in dominating the morphology and performance in pervaporation application. Dehydration of butanol is effective using such membranes with superiority for Mont-25 based membrane. A plausible model for the transport mechanism was proposed and supported by activation energy calculations for the permeation of the individual components and the sorption affinity measurements as well. All these parameters together suggest the arrest of the n-butanol within the macrmolecular chains of the membranes, favored by its chemical affinity. This allows therefore a passageway for the water to cross to the other side of the membrane through plasticization of the chains and creation of free volumes which is known as solution diffusion mechanism. POLYM. ENG. SCI., 54:1560–1570, 2014. © 2013 Society of Plastics Engineers

Polyamide-6 (PA-6) flat sheet membranes have been prepared via casting 20 wt.% solution of polymer in 80 wt.% formic acid onto a glass plate using a doctor blade and coagulation in water bath at am...

Membrane separation technologies have some of advantages are considered a better alternative to traditional methods. Research of novel membranes is very vital for covering the higher required of membrane in several purposes like water desalting technology. In this work polyamide-6/cellulose acetate (PA-6/CA) blend membrane was developed according to the wet phase inversion system. The structures of the prepared membranes were examined by scanning electron microscopy (SEM). SEM images showed uniform particles distribution in the prepared membranes. Moreover, SEM images revealed that the membranes have relatively uniform surface (PA-6/CA). PA-6/CA blend membranes systems are evaluated by using synthetic NaCl solution. The separation performance showed that salt rejection increased with increasing of heat treatment of the casted films and it was improved with increasing of operating pressure.

Polyamide membranes (PA) have been prepared via casting PA polymer in acid media using different percentage of polymer/solvent/additive. Membranes have been characterized using scanning electron microscope (SEM) and operating pressure. The resultant sheet has been applied to separate phenol and phenol derivatives from water feed streams. Membranes have shown better separation properties for all feed mixtures. In all cases, flux and permeability decreased with increasing the amount of polymer in the sheet matrix, while selectivity depended on membrane morphology. The results indicate that the increase in polymeric concentration and operating time leads to decreasing in separation efficiency of membrane sheets.

International audience; It is known that membrane technologies may have a major role to play in the development of environmental-friendly processes, either in gas or liquid separations. In liquid separations, one of the challenging issues is to get membranes with suitable separation properties able also to survive to the exposure of liquid solvents at various temperatures. Aromatic polyimides are known to exhibit a very good stability to a great number of solvents, but their permeability are low because of their rigid carbon skeleton and of their low available free volume; so their uses are mainly limited to gas separations or to filtration processes (MF, UF). To broaden the application area of polyimides in liquid separations, we have prepared and studied the properties of a block ether aromatic copolyimide series where the ether soft block acts both as a selective and a permeable block; we describe attempts to get asymmetric polyetherimide (PEI) membranes having molecular separation properties using various experimental conditions of dry/wet phase inversion. The PEI physical properties and morphologies (SEM) are reported together with their pervaporation properties for water ethanol separation. The PV results showed that rubbery copolyimides can lead to promising asymmetric membranes for liquid liquid separations.