Influence of membrane structure on fouling layer morphology during apple juice clarification

The flux behavior of 0.2 μm nylon, polysulfone (PS), polyvinylidene fluoride (PVDF) and polyethersulfone (PES) membranes was examined during dead-end microfiltration of commercial apple juice. On nylon membranes, a 0.1 μm thick surface fouling layer rapidly formed that acted as a secondary membrane. The colloidal particles retained by this surface layer aggregated to form a thick loose gel structure, producing an anisotropic fouling structure. In contrast, the 4 μm thick surface fouling layer of PES was slower to form and had a more open structure with a lower flux resistance per unit thickness. The morphology of the PES surface layer also did not differ dramatically from the loose gel structure that subsequently formed on top of this secondary membrane. The PS surface fouling layer was similar in structure to nylon whereas the PVDF layer more closely resembled that found with PES. The density of the surface fouling layer did not directly correlate to membrane surface hydrophobicity or pure water flux. Atomic force microscopy (AFM) indicated that surface roughness strongly influenced surface fouling layer morphology. The membrane surface appears to act as a template for the fouling process; therefore, smooth membranes (nylon and PS) produce a dense surface fouling layer whereas this same layer on rough membranes (PES and PVDF) is much more open. Consequently, the fluxes of PES and PVDF membranes are less affected by fouling formation.     

Cellulose acetate nanocomposite ultrafiltration membranes tailored with hydrous manganese dioxide nanoparticles for water treatment applications

Hydrous manganese dioxide (HMO) nanoparticles incorporated cellulose acetate (CA) composite ultrafiltration (UF) membranes are prepared with the aim of improving the water permeation and BSA contaminant removal. The HMO nanoparticles are synthesized from manganese ion and characterized by FT‐IR, XRD, and FESEM. The effect of variation of HMO on CA membranes is probed using FT‐IR, EDAX, contact angle, SEM, and AFM analysis to demonstrate their chemical functionality, hydrophilicity, and morphology. CA/HMO membranes are showing the enhancement in pure water flux (PWF), water uptake, porosity, hydrophilicity, fouling resistance, BSA rejection, and flux recovery ratio (FRR). CA‐1 membrane displayed higher PWF (143.6 Lm²h^?1), BSA rejection (95.9%), irreversible fouling (93.3%), and FRR (93.3%). Overall results confirmed that the CA/HMO nanocomposite UF membranes overcome the bottlenecks and shows potential for water treatment applications.     

Crosslinked poly(ethylene oxide) fouling resistant coating materials for oil/water separation

Potential fouling reducing coating materials were synthesized via free-radical photopolymerization of aqueous solutions of poly(ethylene glycol) diacrylate (PEGDA). Crosslinked PEGDA (XLPEGDA) exhibited high water permeability and good fouling resistance to oil/water mixtures. Water permeability increased strongly with increasing the water content in the prepolymerization water mixture, going from 10 to 150 L μm/(m² h bar) as prepolymerization water content increased from 60 to 80 wt.%. However, molecular weight cutoff decreased as water content increased. These materials were applied to polysulfone (PSF) UF membranes to form coatings on the surface of the PSF membranes. Oil/water crossflow filtration experiments showed that the coated PSF membranes had water flux values 400% higher than that of an uncoated PSF membrane after 24 h of operation, and the coated membranes had higher organic rejection than the uncoated membranes.     

Functionalization of nylon membranes via surface-initiated atom-transfer radical polymerization

The ability to manipulate and control the surface properties of nylons is of crucial importance to their widespread applications. In this work, surface-initiated atom-transfer radical polymerization (ATRP) is employed to tailor the functionality of the nylon membrane and pore surfaces in a well-controlled manner. A simple two-step method, involving the activation of surface amide groups with formaldehyde and the reaction of the resulting N-methylol polyamide with 2-bromoisobutyryl bromide, was first developed for the covalent immobilization of ATRP initiators on the nylon membrane and its pore surfaces. Functional polymer brushes of 2-hydroxyethyl methacrylate (HEMA) and poly(ethylene glycol)monomethacrylate (PEGMA) were prepared via surface-initiated ATRP from the nylon membranes. A kinetics study revealed that the chain growth from the membranes was consistent with a "controlled" process. The dormant chain ends of the grafted HEMA polymer (P(HEMA)) and PEGMA polymer (P(PEGMA)) on the nylon membranes could be reactivated for the consecutive surface-initiated ATRP to produce the corresponding nylon membranes functionalized by P(HEMA)-b-P(PEGMA) and P(PEGMA)-b-P(HEMA) diblock copolymer brushes. In addition, membranes with grafted P(HEMA) and P(PEGMA) brushes exhibited good resistance to protein adsorption and fouling under continuous-flow conditions.     

Tethering hydrophilic polymer brushes onto PPESK membranes via surface-initiated atom transfer radical polymerization

Surface-initiated atom transfer radical polymerization (ATRP) was used to graft hydrophilic comb-like poly((poly(ethylene glycol) methyl ether methacrylate), or P(PEGMA), brushes from chloromethylated poly(phthalazinone ether sulfone ketone) (CMPPESK) membrane surfaces. Prior to ATRP, chloromethylation of PPESK was beforehand performed and the obtained CMPPESK was prepared into porous membranes by phase inversion process. It was demonstrated that the benzyl chloride groups on the CMPPESK membrane surface afforded effective macroinitiators to graft the well-defined polymer brushes. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) confirmed the grafting of P(PEGMA) chains. Water contact angle measurements indicated that the introduction of P(PEGMA) graft chains promoted remarkably the surface hydrophilicity of PPESK membranes. The effects of P(PEGMA) immobilization on membrane morphology, permeability and fouling resistance were investigated. It was found that the comb-like P(PEGMA) grafts brought smaller pore diameters and higher solute rejections to PPESK membranes. The results of dynamic anti-fouling experiments showed the anti-fouling ability of the membranes was significantly improved after the grafting of P(PEGMA) brushes.     

Biofouling-resistance expanded poly(tetrafluoroethylene) membrane with a hydrogel-like layer of surface-immobilized poly(ethylene glycol) methacrylate for human plasma protein repulsions

In general, it is a challenge to control the highly polar material grafting from the chemically inert Teflon-based membrane surface. This work describes the surface modification and characterization of expanded poly(tetrafluoroethylene) (ePTFE) membranes grafted with poly(ethylene glycol) methacrylate (PEGMA) macromonomer via surface-activated plasma treatment and thermally induced graft copolymerization. The chemical composition and microstructure of the surface-modified ePTFE membranes were characterized by Fourier transform infrared spectroscopy (FT-IR), contact angle, and bio-atomic force microscopy (bio-AFM) measurements. Biofouling property of the modified membranes was evaluated by the measurements of the plasma protein (γ-globulin, fibrinogen, or albumin) adsorption determined using an enzyme-linked immunosorbent assay (ELISA). In general, the hydrophilicity of the surface of ePTFE membranes increases with increasing the grafting degree of the copolymerized PEGMA. The highly hydrated PEGMA chain on the resulting ePTFE membranes was found to form a surface hydrogel-like layer with regulated coverage in aqueous state, which can be controlled by the content of PEGMA macromonomer in the reaction solution. The relative protein adsorption was effectively reduced with increasing capacity of the hydration for the PEGMA chain grafted on the ePTFE membrane surface. From both results of protein adsorption and platelet adhesion test in vitro, it is concluded that the PEGMA-grafted hydrophilic ePTFE membranes could provide good biofouling resistance to substantially reduce plasma protein and blood platelet fouling on the membrane surface in human body temperature.     

Modification of polyethersulfone ultrafiltration membranes with phosphorylcholine copolymer can remarkably improve the antifouling and permeation properties

The synthesized phosphorylcholine copolymer composed of 2-methacryloyloxyethylphosphorylcholine (MPC) and n-butyl methacrylate (BMA), blended with polyethersulfone (PES), was used to fabricate antifouling ultrafiltration membranes. Water contact angle measurements confirmed that the hydrophilicity of the MPC-modified PES membranes was enhanced to certain extent. X-ray photoelectron spectroscopy (XPS) analysis verified the substantial enrichment of MPC at the surface of the MPC-modified PES membranes. The adsorption experiments indicated that the adsorption amounts of bovine serum albumin (BSA) on the MPC-modified PES membranes were dramatically decreased in comparison with the control PES membrane. Ultrafiltration experiments were carried out to investigate the effect of MPC modification on the antifouling and permeation properties of the PES membranes, it was found that the rejection ratio of BSA was decreased, the flux recovery ratio was remarkably increased, and the degree of irreversible fouling decreased from 0.46 to 0.09. In addition, the MPC-modified PES membranes could run several cycles without substantial flux loss.     

Self-cleaning Anti-fouling TiO2/Poly(aryl ether sulfone) Composite Ultrafiltration Membranes

A series of novel TiO2/poly(aryl ether sulfone) ultrafiltration membranes with anti-fouling and self-cleaning properties was designed and prepared. First, anti-photocatalytic degraded fluorine contained polv(aryl ether sulfone) matrix(PAES-F) was synthesized. Then the composite membranes were prepared via TiO2 nanopartides and PAES-F polymer matrix by solution blending and non-solvent induced phase inversion methods. Further, separation efficiency, fouling behavior and self-cleaning property of the composite ultrafiltration(UF) membranes were investigated by dead-end filtration experiments using a polyacn lamide solution. The composite UF membranes exhibited outstanding self-cleaning efficiency and anti-photocatalytic degraded property after exposure to simulated sunliglit irradiation.The water flux recovery ratios(FRR)of the optimal composite UF membranes could reach 74.24%, which was attributable to photocatalytic degradation of the organic contaminant by TiO2. And the retention rates of the composite UF membranes could maintain over 97%, which indicated the excellent photocatalytic degradation resistance of the fluorine contained PAES-F matrix. The novel high perfomiance composite UF membranes have a broad application prospect in water treatment.     

The effect of heat treatment of PES and PVDF ultrafiltration membranes on morphology and performance for milk filtration

The flat sheet polyethersulfone (PES) and poly(vinylidene fluoride) (PVDF) membranes were prepared by immersion precipitation technique. The influence of hot air and water treatment on morphology and performance of membranes were investigated. The membranes were characterized by AFM, SEM, cross-flow filtration of milk and fouling analysis. The PES membrane turns to a denser structure with thick skin layer by air treatment at various temperatures during different times. This diminishes the pure water flux (PWF). However the milk permeation flux (MPF) was considerably improved at 100 °C air treatment for 20 min with no change in protein rejection. The smooth surface and slight decrease in surface pore size for air treated PES membrane at 100 °C compared to untreated membrane may cause this behavior for the membrane. The water treatment of PES membranes at 55 and 75 °C declines the PWF and MPF and increases the protein rejection. This is due to slight decrease in membrane surface pore size. The treatment of PES membrane with water at higher temperature results in a porous structure with superior performance. The fouling analysis of 20 min treated membrane indicates that the surface properties of 100 °C air treated and 95 °C water treated PES membranes are improved compared to untreated membrane. The SEM observation depicts that the morphology of air and water treated PVDF membranes was denser and smoother with increasing the heat treatment temperature. The 20 min air treated PVDF membranes at 100 °C and water treated at 95 °C exhibited the highest performance and antifouling properties.     

pH stimuli-responsive and fouling resistance PES membrane fabricated by using photochromic spiropyran and spironaphthoxazine nanofillers for pesticide removal

New fouling resistance and stimulus–responsive nanofiltration membranes were fabricated by adding photochromic spiropyran (SPO) and spironaphthoxazine (SNO) nanofillers to the polyethersulfone (PES) matrix via the phase inversion method. The effect of SPO and SNO, as novel photoresponsive molecule nanofillers, were evaluated in terms of membrane morphology, porosity, wettability, pure water flux (PWF), antifouling resistance, and stimulus–responsive properties. All the modified membranes indicated better performance compared to the bare PES. The membrane PWF was notably enhanced from 7.7 kg/m²h for the bare PES up to 18.68 and 20.58 kg/m²h for the 0.1 wt.% SPO and SNO blended membranes, respectively. Also, the 0.1 wt.% of SNO-based PES membrane indicated the best flux recovery ratio compared to the other membranes. The photo stimulus–responsive assessment showed a color change for both SPO and SNO photochromic in membranes. In the case of variable effect investigation, the response surface methodology at three levels (pressure: 4, 5, 6 bar and flow rate: 50, 100, and 150 L/h) was applied. A suitable flux (23.39 kg/m² h) and high removal efficiency (more than 90%) was achieved at optimum conditions. Also, the modified membranes by photochromic materials were sensitive to environmental variables such as acidic and alkaline conditions by changing their color.     

Improving hydrophilicity and protein antifouling of electrospun poly(vinylidenefluoride-hexafluoropropylene) nanofiber membranes

<正>Poly(vinylidenefluoride-hexafluoropropylene)(PVDF-HFP) nanofiber membranes with improved hydrophilicity and protein fouling resistance via surface graft copolymerization of hydrophilic monomers were prepared.The surface modification involves atmospheric pressure glow discharge plasma(APGDP) pretreatment followed by graft copolymerization of poly(ethylene glycol) methyl ether methacrylate(PEGMA).The success of the graft modification with PEGMA on the PVDF-HFP fibrous membrane is ascertained by X-ray photoelectron spectroscopy(XPS) and attenuated total reflectance Fourier transform infrared measurements(ATR-FTIR).The hydrophilic property of the nanofiber membranes is assessed by water contact angle measurements.The results show that the PEGMA grafted PVDF-HFP nanofiber membrane has a water contact angle of 0°compared with the pristine value of 132°.The protein adsorption was effectively reduced after PEGMA grafting on the PVDF-HFP nanofiber membrane surface.The PEGMA polymer grafting density on the PVDF-HFP membrane surface is measured by the gravimetric method,and the filtration performance is characterized by the measurement of water flux.The results indicate that the water flux of the grafted PVDF-HFP fibrous membrane increases significantly with the increase of the PEGMA grafting density.     

Ultrafiltration polyanionic poly (3-sulfopropyl methacrylate) membranes with enhanced antifouling and water flux

Polyethersulfone (PES) membranes are prevalent in the field of water treatment owing to their exceptional separation efficiency, robust mechanical properties, and resistance to chemical degradation. Nevertheless, these membranes are prone to fouling, resulting in a decrease in both flux and ultrafiltration efficiency. In the present study, PES membranes are blended with poly (3-Sulfopropyl Methacrylate) (PSPMA) in various weight percentages (0%–3%) to improve their antifouling and ultrafiltration properties. The physicochemical properties of the blended membranes, including surface morphology, contact angle, hydrophilicity and surface energy are evaluated. The findings indicate that incorporation PSPMA results in an enhancement of the hydrophilic properties and surface charge of the PES membranes, assessed by employing Bovine Serum Albumin (BSA) as a representative protein. Modified blended membranes display greater Flux Recovery Ratio (FRR%) and exhibit superior fouling resistance. Under the same experimental conditions (0.2 MPa applied pressure), a pure water flux of 154.18 L·m⁻²·h⁻¹ for PES/PSPMA membrane found substantially greater than pure PES membrane (103.52 L·m⁻²·h⁻¹) along with Total Fouling Ratio (TFR) of 36% and 64.9% respectively. Exceptional antimicrobial efficacy for modified membranes is revealed against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) using disc diffusion technique rendering them well-suited for water treatment applications.     

Influence of membrane surface properties on initial rate of colloidal fouling of reverse osmosis and nanofiltration membranes

Recent studies have shown that membrane surface morphology and structure influence permeability, rejection, and colloidal fouling behavior of reverse osmosis (RO) and nanofiltration (NF) membranes. This investigation attempts to identify the most influential membrane properties governing colloidal fouling rate of RO/NF membranes. Four aromatic polyamide thin-film composite membranes were characterized for physical surface morphology, surface chemical properties, surface zeta potential, and specific surface chemical structure. Membrane fouling data obtained in a laboratory-scale crossflow filtration unit were correlated to the measured membrane surface properties. Results show that colloidal fouling of RO and NF membranes is nearly perfectly correlated with membrane surface roughness, regardless of physical and chemical operating conditions. It is further demonstrated that atomic force microscope (AFM) images of fouled membranes yield valuable insights into the mechanisms governing colloidal fouling. At the initial stages of fouling, AFM images clearly show that more particles are deposited on rough membranes than on smooth membranes. Particles preferentially accumulate in the “valleys” of rough membranes, resulting in “valley clogging” which causes more severe flux decline than in smooth membranes.     

Polyethersulfone/polyacrylonitrile blend ultrafiltration membranes with different molecular weight of polyethylene glycol: preparation,morphology and antifouling properties

Asymmetric ultrafiltration (UF) membranes were prepared from blends of polyethersulfone (PES)/polyacrylonitrile (PAN) via phase inversion method induced by immersion precipitation. Polyethylene glycol (PEG) with four different molecular weights was used as pore former and hydrophilic polymeric additive. N,N‐dimethylformamide (DMF) and water were used as solvent and coagulant (nonsolvent), respectively. The effects of different proportion of PES/PAN and molecular weight of PEG on morphology and performance of the prepared membranes were investigated. Performance of the membranes was evaluated using UF experiments of pure water and buffered bovine serum albumin (BSA) solution as feed. The contact angle measurements indicated that the hydrophilicities of PES/PAN membrane increase by increasing the PAN concentration in the casting solution. However, performance of the membranes improves by increasing the PAN concentration in the casting solution up to 20% and then decreases with further addition of PAN. It was found out that the rejection of BSA decreases with increasing the PAN concentration in the casting solution. Furthermore, it was found that the performance of the membranes increases by increasing the molecular weight of PEG up to 1500 Da and then decreases with the higher molecular weights. The morphology of the prepared membranes was studied by scanning electron microscopy. Copyright © 2011 John Wiley & Sons, Ltd.     

Enhancing the antifouling property of polyethersulfone ultrafiltration membranes through surface adsorption-crosslinking of poly(vinyl alcohol)

An adsorption-crosslinking process of poly(vinyl alcohol) (PVA) was introduced to modify the surface of polyethersulfone (PES) ultrafiltration membranes for enhancement of their antifouling property. XPS and water contact angle measurement confirmed the obvious enhancement of surface hydrophilicity. Ultrafiltration results showed that the spreading of PVA chains over the hydrophobic membrane surface caused substantial but acceptable decrease on membrane flux. The fouling type analysis indicated that PVA adsorption effectively improved the antifouling property of PES membranes. With a PVA concentration of 0.5 wt% and three cycles of alternative adsorption-crosslinking, the total and irreversible fouling ratio of modified membranes were 0.38 and 0.22, respectively, much lower than those of control PES membrane (0.61 and 0.47), and the flux recovery ratio was increased accordingly. The long-term ultrafiltration experiment demonstrated the improvement of recycling property and the reliability of adsorption-crosslinking process.     

Adsorption of amylase enzyme on ultrafiltration membranes

A method to measure the static adsorption on membrane surfaces has been developed and described. The static adsorption of amylase-F has been measured on two different ultrafiltration membranes, both with a cutoff value of 10 kDa (a PES membrane and the ETNA10PP membrane, which is a surface-modified PVDF membrane). The adsorption follows the Langmuir adsorption theory. Thus, the static adsorption consists of monolayer coverage and is expressed both as a permeability drop and an adsorption resistance. From the adsorption isotherms, the maximum static permeability drops and the maximum static adsorption resistances are determined. The maximum static permeability drop for the hydrophobic PES membrane is 75%, and the maximum static adsorption resistance is 0.014 m2.h.bar/L. The maximum static permeability drop for the hydrophilic surface-modified PVDF membrane (ETNA10PP) is 23%, and the maximum static adsorption resistance is 0.0046 m2.h.bar/L. The difference in maximum static adsorption, by a factor of around 3, affects the performance during the filtration of a 5 g/L amylase-F solution at 2 bar. The two membranes behave very similarly during filtration with almost equal fluxes and retentions even though the initial water permeability of the PES membrane is around 3 times larger than the initial water permeability of the ETNA10PP membrane. This is mainly attributed to the larger maximum static adsorption of the PES membrane. The permeability drop during filtration exceeds the maximum static permeability drop, indicating that the buildup layer on the membranes during filtration exceeds monolayer coverage, which is also seen by the increase in fouling resistance during filtration. The accumulated layer on the membrane surface can be described as a continually increasing cake-layer thickness, which is independent of the membrane type. At higher concentrations of enzyme, concentration polarization effects cannot be neglected. Therefore, stagnant film theory and the osmotic pressure model can describe the relationship between flux and bulk concentration.     

Enhanced separation performance of PVDF/PVP-g-MMT nanocomposite ultrafiltration membrane based on the NVP-grafted polymerization modification of montmorillonite (MMT)

A novel hydrophilic nanocomposite additive (PVP-g-MMT), coupling of hydrophilic modifier, self-dispersant, and pore-forming agent (porogen), was synthesized by the surface modification of montmorillonite (MMT) with N-vinylpyrrolidone (NVP) via "grafting from" polymerization in the presence of H(2)O(2)-NH(3)·H(2)O as the initiator, and then the nanocomposite membrane of poly(vinylidene fluoride) (PVDF) and PVP-g-MMT was fabricated by wet phase inversion onto clean glass plates. The existence and dispersion of PVP-g-MMT had a great role on structures, morphologies, surface composition, and chemistry of the as-prepared nanocomposite membranes confirmed by varieties of spectroscopic and microscopic characterization techniques, all of which were the correlated functions of PVP-g-MMT content in casting solution. By using the dead-end filtration of protein aqueous solution, the performance of the membrane was evaluated. It was seen that all of the nanocomposite membranes showed obvious improvement of water flux and proper BSA rejection ratio, compared to the control PVDF membrane. Meanwhile, dynamic BSA fouling resistance and flux recovery properties were also greatly enhanced due to the changes of surface hydrophilicity and morphologies. All the experimental results indicated that the as-prepared PVDF nanocomposite membranes showed better separation performances than the control PVDF membrane. Hopefully, the demonstrated method of hydrophilic nanocomposite additive synthesis would be applied for commonly hydroxyl group-containing inorganic nanoparticles, which was favorable to fabricate hydrophilic nanoparticle-enhanced polymer membranes for water treatment.     

Influence of membrane fouling by (pretreated) surface water on rejection of pharmaceutically active compounds (PhACs) by nanofiltration membranes

The effects of surface water pretreatment on membrane fouling and the influence of these different fouling types on the rejection of 21 neutral, positively and negatively charged pharmaceuticals were investigated for two nanofiltration membranes. Untreated surface water was compared with surface water, pretreated with a fluidized anionic ion exchange and surface water, pretreated with ultrafiltration. Fouling the nanofiltration membranes with anionic ion exchange resin effluent, resulted in the deposition of a mainly colloidal fouling layer, with a rough morphology. Fouling the nanofiltration membranes with ultrafiltration permeate, resulted in the deposition of a smooth fouling layer, containing mainly natural organic matter. The fouling layer on the nanofiltration membranes, caused by the filtration of untreated surface water, was a combination of both colloids and natural organic matter.Rejection of pharmaceuticals varied the most for the membranes, fouled with the anionic ion exchange effluent, and variations in rejection were caused by a combination of cake-enhanced concentration polarisation and electrostatic (charge) effects. For the membranes, fouled with the other two water types, variations in rejection were smaller and were caused by a combination of steric and electrostatic effects.Changes in membrane surface hydrophobicity due to fouling, changed the extent of partitioning and thus the rejection of hydrophobic, as well as hydrophilic pharmaceuticals.     

Tailoring polyethersulfone/quaternary ammonium polysulfone ultrafiltration membrane with positive charge for dye and salt selective separation

Polyethersulfone (PES)/quaternary ammonium polysulfone (QAPSf) blend ultrafiltration (UF) membranes with positive charge were fabricated by nonsolvent induced phase separation (NIPS) for use in dye and salt selective separation. QAPSf was synthesized by nucleophilic substitution with chloromethylated polysulfone (CMPSf). The effect of the PES/QAPSf mass ratio on the morphology and performance of blend UF membranes were studied. The membranes' zeta potentials gradually changed from negative to positive with decreases in the PES/QAPSf mass ratio. At PES/QAPSf mass ratios of 30:70 and 10:90, the zeta potentials of the membranes reached +1.8 mV and + 5.9 mV, respectively. Additionally, the contact angles of the membranes decreased from 74° to 52° as the QAPSf content increased from 0 wt% to 90 wt%. Furthermore, the membrane with a PES/QAPSf mass ratio of 30:70 showed a high water permeance (181.4 LMH bar⁻¹) and excellent dye and salt selective separation performance. The rejection ratios reached 99.1%, 87.8%, 99.6%, and 92.4% for dyes Congo red, methyl blue, Alixin blue 8GX, and basic blue 24, respectively, while those for salts Na₂SO₄, MgSO₄, MgCl₂, and NaCl were ≤ 10%. In addition, the PES/QAPSf membranes showed excellent antifouling performance and good operating stability with dye-salt mixtures of various pHs and salt concentrations.     

SYNTHESIS OF AN AMPHIPHILIC PPESK-g-P(PEGMA) GRAFT COPOLYMER VIA ATRP AND ITS USE IN BLEND MODIFICATION OF PPESK MEMBRANES

Preparation of an amphiphilic graft copolymer having poly(phthalazinone ether sulfone ketone)(PPESK) as main chains was carried out by atom transfer radical polymerization(ATRP).The precursor,chloromethylated PPESK (CMPPESK),was prepared by using chioromethylether as chloromethylation agent.Then,poly(ethylene glycol) methyl ether methacrylate(PEGMA) was used as monomer to synthesize PPESK-g-P(PEGMA) by ATRP method under the catalysis of a cuprous chloride/2,2'-bipyridyl system.PPESK/PPESK-g-P(PEGMA) blen...