The occurrence of ultrafiltration(UF)membrane fouling frequently hampers the sustainable advancement of UF technology.Reactive self-cleaning UF membranes can effectively alleviate the problem of membrane fouling.Never...The occurrence of ultrafiltration(UF)membrane fouling frequently hampers the sustainable advancement of UF technology.Reactive self-cleaning UF membranes can effectively alleviate the problem of membrane fouling.Nevertheless,the self-cleaning process may accelerate membrane aging.Addressing these concerns,we present an innovative design concept for composite self-healing materials based on self-cleaning UF membranes.To begin,TiO_(2)nanoparticles were incorporated into the polymer molecular structure via molecular design,resulting in the synthesis of TiO_(2)/carboxyl-polyether sulfone(PES)hybrid materials.Subsequently,the nonsolvent-induced phase inversion technique was employed to prepare a novel of UF membrane.Lastly,a polyvinyl alcohol(PVA)hydrogel coating was applied to the hybrid UF membrane surface to create PVA@TiO_(2)/carboxyl-PES self-healing reactive UF membranes.By establishing a covalent bond,the TiO_(2)nanoparticles were effectively and uniformly dispersed within the UF membrane,leading to exceptional self-cleaning properties.Furthermore,the water-absorbing and swelling properties of PVA hydrogel,along with its capacity to form hydrogen bonds with water molecules,resulted in UF membranes with improved hydrophilicity and active self-healing abilities.The results demonstrated that the water contact angle of PVA@5%TiO_(2)/carboxyl-PES UF membrane was 43.1°.Following a 1-h exposure to simulated solar exposure,the water flux recovery ratio increased from 48.16%to 81.03%.Moreover,even after undergoing five cycles of 12-h simulated sunlight exposure,the UF membranes exhibited a consistent retention rate of over 97%,thus fully demonstrating their exceptional self-cleaning,antifouling,and selfhealing capabilities.We anticipate that the self-healing reactive UF membrane system will serve as a pioneering and comprehensive solution for the self-cleaning antifouling challenges encountered in UF membranes while also effectively mitigating the aging effects of reactive UF membranes.展开更多
A non-solvent induced phase separation(NIPS)process was used to fabricate a series of sulfonated polyethersulfone(SPES)membranes blending with different concentrations of SBA-15-g-PSPA with the applications in the ult...A non-solvent induced phase separation(NIPS)process was used to fabricate a series of sulfonated polyethersulfone(SPES)membranes blending with different concentrations of SBA-15-g-PSPA with the applications in the ultrafiltration(UF)process.SBA-15 was modified with 3-methacrylate-propyltrime thoxysilane(MPS)to form SBA-15-g-MPS.It was further modified with the charge tailorable polymer chains by reacting with 3-sulfopropyl methacrylate potassium salt.The nanoparticles were uniformly dispersed and finger-like channels were developed within the membrane.The adding of surface modified SBA-15-g-PSPA nanoparticles has significantly improved membrane water permeability,hydrophilicity,and antifouling properties.The pure water fluxes of the composite SPES membranes were significantly higher than the pristine SPES membrane.For the membrane containing 5%(mass)of SBA-15-g-PSPA(MSSPA5),the pure water flux was increased dramatically to 402.15 Lm^(-2)·h^(-1),which is ~1.5 times that of MSSPA0(268.0 Lm^(-2)·h^(-1)).The high flux rate was achieved with 3%(mass)of SBA-15 nanoparticles with retained high rejection ratio 98%for natural organic matter.The results indicate that the fashioned composite membrane comprising SBA-15-g-PSPA nanoparticles have a promising future in ultrafiltration applications.展开更多
Membrane fouling is one of the major obstacles for reaching a high flux over a prolonged period of ultrafiltration(UF)process.In this study,a sulfonated-polyethersulfone(SPES)/nano-TiO2 composite UF membrane with ...Membrane fouling is one of the major obstacles for reaching a high flux over a prolonged period of ultrafiltration(UF)process.In this study,a sulfonated-polyethersulfone(SPES)/nano-TiO2 composite UF membrane with good anti-fouling performance was fabricated by phase inversion and self-assembly methods.The TiO2 nanoparticle self-assembly on the SPES membrane surface was confirmed by X-ray photoelectron spectroscopy (XPS)and FT-IR spectrometer.The morphology and hydrophilicity were characterized by scanning electron microscopy(SEM),atomic force microscopy(AFM)and contact angle goniometer,respectively.The anti-fouling mechanism of composite UF membrane was discussed through the analysis of the micro-structure and component of UF membrane surface.The results showed that the TiO2 content and the micro-structure of the composite UF membrane surface had great influence on the separation and anti-fouling performance.展开更多
Polysulfone(PSF) is extensively used for the production of ultrafiltration(UF) membranes thanks to its high strength,chemical stability,and good processibility.However,PSF is intrinsically hydrophobic,and hydrophilic ...Polysulfone(PSF) is extensively used for the production of ultrafiltration(UF) membranes thanks to its high strength,chemical stability,and good processibility.However,PSF is intrinsically hydrophobic,and hydrophilic modification is always required to PSF-based membranes if they are intended to be used in aqueous systems.Facile strategies to prepare hydrophilic PSF membranes are thus highly demanded.Herein we spray coat a PSF-based amphiphilic block polymer onto macroporous substrates followed by selective swelling to prepare flat-sheet PSF UF membranes.The polymer is a triblock polymer containing PSF as the majority middle block tethered with shorter block of polyethylene glycol(PEG) on both ends,that is,PEG-b-PSF-b-PEG.We use the technique of spray coa ting to homogeneously dispense diluted triblock polymer solutions on the top of macroporous supports,instantly resulting in uniform,defect-free polymer coating layers with the thickness down to ~1.2 μm.The bi-layered composite structures are then immerged in ethanol/acetone mixture to generate mesoscale pores in the coating layers following the mechanism of selective swelling-induced pore generation,thus producing composite membranes with the mesoporous triblock polymer coating as the selective layers.This facile strategy is free from additional hydrophilic modification and much smaller dosages of polymers are used compared to conventional casting methods.The pore sizes,porositie s,hydrophilicity,and consequently the separation properties of the membranes can be flexibly tuned by changing the swelling duration and the composition of the swelling bath.This strategy combining spray coating and selective swelling is upscalable for the production of highperformance PSF UF membranes.展开更多
The past few decades have witnessed rapid gains in our demands of antifouling membranes such as water purification membranes and hemodialysis membranes.A variety of methodologies have been proposed for improving the a...The past few decades have witnessed rapid gains in our demands of antifouling membranes such as water purification membranes and hemodialysis membranes.A variety of methodologies have been proposed for improving the antifouling performance and the hemocompatibility of the membranes.In this study,a series of copolymers(PSF-PESSB)containing polysulfone(PSF)and poly(arylene ether sulfone)bearing pendant zwitterionic sulfobetaine groups(PESSB)were prepared via one-pot polycondensation.Subsequently,the ultrafiltration(UF)membranes were prepared from different zwitterion-containing copolymers.The prepared membranes showed high thermal stability and mechanical properties.Besides,it also displayed attractive antifouling performance and blood compatibility.Compared with the original PSF membrane,the amount of protein absorption on the modified membrane was reduced;the flux recovery ratio and the resistance to blood cells were significantly improved.The results of this work suggest that PSF-PESSB membranes are expected to be applied in blood purification.The introduction of zwitterion-containing polymers to membranes paves ways for developing advanced hemodialysis technologies for crucial process.展开更多
Polyphenylsulfone(PPSU)ultrafiltration membrane with different structures was prepared by nonsolvent-induced phase separation.The effects of coagulation bath conditions(concentration and temperature)on membrane morpho...Polyphenylsulfone(PPSU)ultrafiltration membrane with different structures was prepared by nonsolvent-induced phase separation.The effects of coagulation bath conditions(concentration and temperature)on membrane morphology,pure water flux,pore size,porosity,and contact angle were studied and discussed based on ternary-phase diagrams.Results indicated that water had stronger coagulant power than ethanol,and that the morphology of the membrane prepared from the polyphenylsulfone/1-methyl-2-pyrrolidinone/H_(2)O(PPSU/NMP/H_(2)O)system had finger-like structures.Conversely,sponge-like structures were observed for the PPSU/NMP/(NMP-H_(2)O)and PPSU/NMP/(70 NMP-EtOH-H_(2)O)systems.Ethanol also greatly influenced on membrane structures.According to the Scanning electronic microscopy(SEM)image,the composition(mass fraction)of casting solution is 16%PPSU-84%NMP and the coagulation bath consisting of 70%NMP-26%H_(2)O-4%C_(2)H_(5)OH.Meanwhile,the PPSU ultrafiltration membrane with spong-like was prepared under 8℃coagulation bath.The formation of sponge-like structure reduces the pure water flux of ppsu membrane from 488.39 L·m^(-2)·h^(-1)to 36.04 L·m^(-2)·h^(-1).It also reduces the gas permeability,porosity,and pore size of the membrane.The addition of ethanol and NMP into the coagulation bath increases the roughness of the PPSU ultrafiltration membrane and reduces the hydrophilicity of the membrane.展开更多
Polyethylene glycol(PEG) membranes with different molecular mass cut-offs were used to treat oil/water emulsion, and the effects of experimental conditions including pressure, temperature and different opera- ting mod...Polyethylene glycol(PEG) membranes with different molecular mass cut-offs were used to treat oil/water emulsion, and the effects of experimental conditions including pressure, temperature and different opera- ting modes on permeate flux and removal rate of chemical oxygen demand (COD_ Cr) were studied. The results show that the permeate flux of ultrafiltration membrane is influenced by pressure and temperature; practical pressure is chosen to be 0.30.7MPa for the PEG with molecular mass cut-offs of 8000 and 0.71.0 MPa for the PEG with molecular mass cut-offs of 2500; and the practical temperature is chosen to be 2532℃. Different operating modes of ultrafiltration also influence the permeate flux and removal rate of COD_ Cr. The ultrafiltration membrane of intermittent cross-flow operating mode is easier to be influenced by blocky polarization and contamination than that of sequential cross-flow operating mode. Removal rate of COD_ Cr in intermittent cross-flow and sequential cross-flow condition can be maintained at about 93%.展开更多
With the rapid increase of water contamination,membrane separation technology and their corresponding molecular weight cut-off(MWCO) evaluation method become more necessary.In this study,Panax notoginseng saponins was...With the rapid increase of water contamination,membrane separation technology and their corresponding molecular weight cut-off(MWCO) evaluation method become more necessary.In this study,Panax notoginseng saponins was used as a new standard marker to determinate ultrafiltration(UF) membrane MWCOs,series of Millipore membranes were selected as control group to analyze and calculate the relationship between retention rate and MWCOs with exponential or logarithmic equation.A new and convenient method was provided for determining the membrane MWCO by modeling analysis retention rate with MWCOs,and the regression coefficients >0.990.The feasibility and practicability of established method was verified by different manufactures' membrane and dextrans.In the detection progress,as the main ingredient of Panax notoginseng saponins,Notoginsenoside R_1,Ginsenoside Rg_1,Ginsenoside Rb_1 and Ginsenoside Rd with different surface activity,the MWCO range of UF membranes can be divided into two zones mainly due to the retention rate difference among Notoginsenoside R_1,Ginsenoside Rg_1,Ginsenoside Rb_1 and Ginsenoside Rd.Zone 1,1000-10000;and Zone II,10000-100000.Thus,the new method would be helpful to improve the applicability of UF membrane in separation technology.展开更多
Broadly speaking, this study aims to develop "batik" dyes wastewater treatment technologies by hybrid process that combines Fenton oxidation and separation using ultrafiltration membranes. Specifically, the purpose ...Broadly speaking, this study aims to develop "batik" dyes wastewater treatment technologies by hybrid process that combines Fenton oxidation and separation using ultrafiltration membranes. Specifically, the purpose of this study was to determine the effect of membrane characteristics, feed solution pH, operating pressure of "Dead-end" membrane reactor, and the frequency of membranes which uses on the percentage of COD reduction in "batik" wastewater. In this study, the filtrate from wastewater pre-treatment with Fenton oxidation, both without and with addition of activated carbon, is passed to the ultrafiltration (UF) separation system. Fenton oxidation process was carried out at optimum conditions, i.e. at pH 3, temperature 50 ℃, and the addition FeSO4·7H2O and H2O2 at 747-830 mg/L and 1,168-1,460 mg/L, respectively. The optimum reduction percentage of COD can be achieved when the membranes used for separation has a pore size of 0.01 to 0.015 lam, feed solution pH 2, operating pressure 1 atm and frequency of membranes uses I x. To determine the fouling potential on ultrafiltration membranes that are used, flux measurements were performed 3 times for each membrane. These stages can see that the flux decline reached 22.5% when the effluent filtered directly to the membrane; 17.3% when performed pre-treatment prior to separation processes using membranes and 10% when combined pre-treatment process, use of activated carbon and the separation using ultrafiltration membranes.展开更多
Various hydrophilic poly(ethylene-co-vinyl alcohol)(EVOH)were used herein to precisely control the structure and hydrodynamic properties of polysulfone(PSF)membranes.Particularly,to prepare pristine PSF and PSF/EVOH b...Various hydrophilic poly(ethylene-co-vinyl alcohol)(EVOH)were used herein to precisely control the structure and hydrodynamic properties of polysulfone(PSF)membranes.Particularly,to prepare pristine PSF and PSF/EVOH blends with increasing vinyl alcohol(VOH:73%,68%,56%),the non-solvent-induced phase separation(NIPS)technique was used.Polyethylene glycol was used as a compatibilizer and as a porogen in N,Ndimethylacetamide.Rheological and ultrasonic separation kinetic measurements were also carried out to develop an ultrafiltration membrane mechanism.The extracted membrane properties and filtration capabilities were systematically compared to the proposed mechanism.Accordingly,the addition of EVOH led to an increase in the rheology of the dopes.The resulting membranes exhibited a microporous structure,while the finger-like structures became more evident with increasing VOH content.The PSF/EVOH behavior was changed from immediate to delayed segregation due to a change in the hydrodynamic kinetics.Interestingly,the PSF/EVOH32 membranes showed high hydrophilicity and achieved a pure water permeability of 264 L·m^(–2)·h^(–1)·bar^(–1),which was higher than that of pure PSF membranes(171 L·m^(–2)·h^(–1)·bar^(–1)).In addition,PSF/EVOH32 rejected bovine serum albumin at a high rate(>90%)and achieved a significant restoration of permeability.Finally,from the thermodynamic and hydrodynamic results,valuable insights into the selection of hydrophilic copolymers were provided to tailor the membrane structure while improving both the permeability and antifouling performance.展开更多
Pre-oxidation is widely used to reduce ultrafiltration membrane fouling. However, the variation in the composition of microbial communities and extracellular polymeric substances (EPSs) accompanying pre-oxidation in...Pre-oxidation is widely used to reduce ultrafiltration membrane fouling. However, the variation in the composition of microbial communities and extracellular polymeric substances (EPSs) accompanying pre-oxidation in drinking water treatment has received little attention. In this study, hydrogen peroxide (H2O2) was used in a coagulation- ultrafiltration process with Al2(SO4)3.18H2O. A long-term reactor experiment (60 d) showed that pre-oxidation alleviated membrane fouling, mainly due to its inhibition of microbial growth, as observed by flow cytometry measurements of the membrane tank water. Further analysis of the formed cake layer demonstrated that the corresponding levels of EPS released from the microbes were lower with than without H202 treatment. In comparison to polysaccharides, proteins dominated the EPS. 2D-electrophoresis showed little difference (p 〉 0.05, Student's t-test) in the composition of proteins in the cake layer between the treatments with and without H2O2. The molecular weights of proteins ranged from approximately 30-50 kDa and the majority of isoelectric points ranged from 6 to 8. Highthroughput sequencing showed that the predominant bacteria were Proteobacteria, Bacteroidetes, and Verrucomicrobia in both cake layers. However, the relative abundance of Planctomycetes was higher in the cake layer with H2O2 pre-oxidation, which was likely probably due to the strong oxidative resistance of its cell wall. Overall, our findings clarify the fundamental molecular mechanism in H2O2 pre-oxidation for ultrafiltration membrane bio-fouling alleviation in drinking water treatment.展开更多
Membrane fouling has been investigated by using a polysulfone ultrafiltration membrane with the molecular weight cutoff of 20 kDa to treat crushed coal pressurized gasification wastewater. Under the conditions of diff...Membrane fouling has been investigated by using a polysulfone ultrafiltration membrane with the molecular weight cutoff of 20 kDa to treat crushed coal pressurized gasification wastewater. Under the conditions of different feed pressures, the permeate flux declines and rejection coefficients of pollutants referring to three parameters (total organic carbon (TOC), chroma and turbidity) were studied. The membrane fouling mechanism was simulated with three classical membrane fouling models. The membrane image and pollutants were analyzed by scanning electron microscopy and gas chromatography-mass spectrography (GC-MS). The results indicate that the permeate flux decreases with volume reduction factor before reaching a constant value. The rejection coefficients were also measured: fTOC = 70.5%,fc = 84.9% andfa- = 91%. Further analysis shows that the higher the feed pressure is, the sooner the permeate flux reaches constant value and the more sharply the permeate flux declines. Constant flux indicates a nonlinear growth with feed pressure (PF): when Pr equals 1.2 bar, the mark for the critical flux, slight membrane fouling occurs; when PF exceeds 1.2 bar, cake layer pollution aggravates. Also the rejection coefficients of global pollutant increases slightly with PF, suggesting the possibility of cake compression when PF exceeds 1.2 bar. Through regression analysis, the fouling of polysulfone ultrafiltration membrane could be fitted very well by cake filtration model. The membrane pollutants were identified as phthalate esters and long-chain alkenes by GC-MS, and a certain amount of inorganic pollutants by X-ray photoelectron spectroscopy.展开更多
Novel poly(aryl ether sulfone ketone)s (PAESK) were synthesized from bisphenol A (BPA), 9,9'-bis(4-hydroxyphenyl) fluorene (BHPF), 4,4'-dichlorodiphenylsulfone (DCS) and 4,4'-difluorobenzophenone (DFB...Novel poly(aryl ether sulfone ketone)s (PAESK) were synthesized from bisphenol A (BPA), 9,9'-bis(4-hydroxyphenyl) fluorene (BHPF), 4,4'-dichlorodiphenylsulfone (DCS) and 4,4'-difluorobenzophenone (DFB) via nucleophilic substitution polymerization, which were subsequently used to fabricate ultrafiltration membrane by phase-inversion method for high temperature condensed water treatment. The obtained high molecular weight co-polymers with fluorene group with good solubility and good thermal stability, can be easily cast into flexible, white and non-transparent fiat films. The influence of molar ratio of BPA and BHPF on the properties of the prepared co-polymers and membranes was investigated in detail. SEM study of the morphology of the membranes indicated that the prepared membranes possessed homogeneous pores on the top surface and were sponge-like or finger-like in cross-section. Pure water flux of the membranes increased from 71.87 L·m-2.h-1 to 247.65 L·m-2.h-1, while the retention of BSA decreased slightly, and the water contact angle decreased from 82.1 ° to 55.6° with the PVP concentration from 0 wt% to 10 wt%. With increasing concentration of PVP, the mechanical properties of membranes decreased, while the thermal stability increased. The permeate flux measurement showed that the PAESK membrane had the potential for high temperature condensed water treatment.展开更多
The sensitivity of poly(arylsulfone)(PSf) for UV irradiation in different solvents(water and ethanol) was investigated. It is confirmed that acrylic acid(AA) and acrylamide(AAm) are grafted only onto the surface of th...The sensitivity of poly(arylsulfone)(PSf) for UV irradiation in different solvents(water and ethanol) was investigated. It is confirmed that acrylic acid(AA) and acrylamide(AAm) are grafted only onto the surface of the membrane instead of the interior by FTIR and scanning electron microscope(SEM). The membrane performance(Δ J/J 0 and contact angle θ ) after photografting was studied. In the range of conditions used, the grafting yield increases with irradiation time and monomer concentration growing. After photografting and N 3 dimethyl aminopropyl N' ethycarbodiimide hydrochloride(EDC) activation, PSf membrane was immobilized with hydrogen peroxide oxidoreductase, and showed a higher activity than the control membrane.展开更多
Coagulation plays an important role in alleviating membrane fouling, and a noticeable problem is the development of microorganisms after long-time operation, which gradually secrete extracellular polymeric substances...Coagulation plays an important role in alleviating membrane fouling, and a noticeable problem is the development of microorganisms after long-time operation, which gradually secrete extracellular polymeric substances(EPS). To date, few studies have paid attention to the behavior of microorganisms in drinking water treatment with ultrafiltration(UF)membranes. Herein, the membrane biofouling was investigated with different aluminum and iron salts. We found that Al_2(SO_4)_3·18 H_2O performed better in reducing membrane fouling due to the slower growth rate of microorganisms. In comparison to Al_2(SO_4)_3·18H_2O,more EPS were induced with Fe_2(SO_4)_3·x18H_2O, both in the membrane tank and the sludge on the cake layer. We also found that bacteria were the major microorganisms, of which the concentration was much higher than those of fungi and archaea. Further analyses showed that Proteobacteria was dominant in bacterial communities, which caused severe membrane fouling by forming a biofilm, especially for Fe_2(SO_4)_3·x18H_2O. Additionally, the abundances of Bacteroidetes and Verrucomicrobia were relatively higher in the presence of Al_2(SO_4)_3·18 H_2O,resulting in less severe biofouling by effectively degrading the protein and polysaccharide in EPS. As a result, in terms of microorganism behaviors, Al-based salts should be given preference as coagulants during actual operations.展开更多
As a routine measurement to alleviate membrane fouling, hydraulic cleaning is of great significance for the steady operation of ultrafiltration(UF) systems in water treatment processes. In this work, a comparative s...As a routine measurement to alleviate membrane fouling, hydraulic cleaning is of great significance for the steady operation of ultrafiltration(UF) systems in water treatment processes. In this work, a comparative study was performed to investigate the effects of the composition of backwash water on the hydraulic cleaning performance of UF membranes fouled by humic acid(HA). Various types of backwash water, including UF permeate, Milli-Q water, Na Cl solution, CaCl_2 solution and HA solution, were compared in terms of hydraulically irreversible fouling index, total surface tension and residual HA. The results indicated that Milli-Q water backwash was superior to UF permeate backwash in cleaning HA-fouled membranes, and the backwash water containing Na+or HA outperformed Milli-Q water in alleviating HA fouling. On the contrary, the presence of Ca^(2+) in backwash water significantly decreased the backwash efficiency. Moreover, Ca^(2+) played an important role in foulant removal, and the residual HA content closely related to the residual Ca^(2+) content.Mechanism analysis suggested that the backwash process may involve fouling layer swelling, ion exchange, electric double layer release and competitive complexation. Ion exchange and competitive complexation played significant roles in the efficient hydraulic cleaning associated with Na+and HA, respectively.展开更多
Sodium hypochlorite(NaClO)is a commonly applied cleaning agent for ultrafiltration membranes in water and wastewater treatment.Long-term exposure to NaClO might change the properties and performance of polymeric membr...Sodium hypochlorite(NaClO)is a commonly applied cleaning agent for ultrafiltration membranes in water and wastewater treatment.Long-term exposure to NaClO might change the properties and performance of polymeric membranes,and ultimately shorten membrane lifespan.Active species in NaClO solution vary with solution pH,and the aging effects can change depending on the membrane material.In this study,the aging of polyvinylidene fluoride(PVDF)and polyethersulfone(PES)membranes by NaClO at pH 3–11 was investigated by examining variations in chemical composition,surface charge,surface morphology,mechanical strength,permeability,and retention ability.Polyvinyl pyrrolidone(PVP),which was blended in both membranes,was oxidized and dislodged due to NaClO aging at all investigated pH values,but the oxidation products and dislodgement ratio of PVP varied with solution pH.For the PVDF membrane,NaClO aging at pH 3–11 caused a moderate increase in permeability and decreased retention due to the oxidation and release of PVP.The tensile strength decreased only at pH 11 because of the defluorination of PVDF molecules.For the PES membrane,NaClO aging at all investigated pH resulted in chain scission of PES molecules,which was favored at pH 7 and 9,potentially due to the formation of free radicals.Therefore,a decrease in tensile strength and retention ability,as well as an increase in permeability,occurred in the PES membrane for NaClO aging at pH 3–11.Overall,the results can provide a basis for selecting chemical cleaning conditions for PVDF and PES membranes.展开更多
Membrane fouling is always the biggest problem in the practice of membrane separation technologies,which strongly impacts their applicability,separation efficiency,cost effectiveness,and service lifespan.Herein,a simp...Membrane fouling is always the biggest problem in the practice of membrane separation technologies,which strongly impacts their applicability,separation efficiency,cost effectiveness,and service lifespan.Herein,a simple but effective 3D modification approach was designed for permanently functionalizing polymeric membranes by directly cross-linking polyvinyl alcohol(PVA)under gamma-ray irradiation at room temperature without any additives.After the modification,a PVA layer was constructed on the membrane surface and the pore inner surface of polyvinylidene fluoride(PVDF)membranes.This endowed them with good hydrophilicity,low adsorption of protein model foulants,and easy recoverability properties.In addition,the pore size and distribution were customized by controlling the PVA concentration,which enhanced the rejection ability of the resultant membranes and converted them from microfiltration to ultrafiltration.The crosslinked PVA layer was equipped with the resultant membranes with good resistance to chemical cleaning by acidic,alkaline,and oxidative reagents,which could greatly prolong the membrane service lifetime.Furthermore,this approach was demonstrated as a universal method to modify PVDF membranes with other hydrophilic macromolecular modifiers,including polyethylene glycol,sodium alginate,and polyvinyl pyrrolidone.This modification of the membranes effectively endowed them with good hydrophilicity and antifouling properties,as expected.展开更多
Processing bioactive peptides from natural sources using electrodialysis with ultrafiltration membranes(EDUF)have gained attention since it can fractionate in terms of their charge and molecular weight.Quinoa is a pse...Processing bioactive peptides from natural sources using electrodialysis with ultrafiltration membranes(EDUF)have gained attention since it can fractionate in terms of their charge and molecular weight.Quinoa is a pseudo-cereal highlighted by its high protein content,amino acid profile and adapting growing conditions.The present work aimed at the production of quinoa peptides through fractionation using EDUF and to test the fractions according to antihypertensive and antidiabetic activity.Experimental data showed the production of peptides ranging between 0.4 and 1.5 k Da.Cationic(CQPF)(3.01%),anionic(AQPF)(1.18%)and the electrically neutral fraction quinoa protein hydrolysate(QPH)-EDUF(~95%)were obtained.In-vitro studies showed the highest glucose uptake modulation in L6 cell skeletal myoblasts in presence of QPH-EDUF and AQPF(17%and 11%)indicating potential antidiabetic activity.The antihypertensive effect studied in-vivo in spontaneously hypertensive rats(SHR),showed a decrease in systolic blood pressure in presence of the fractionated peptides,being 100 mg/kg a dose comparable to Captopril(positive control).These results contribute to the current knowledge of bioactive peptides from quinoa by reporting the relevance of EDUF as tool to produce selected peptide fractions.Nevertheless,further characterization is needed towards peptide sequencing,their respective role in the metabolism and scaling-up production using EDUF.展开更多
The effect of additives CaCl\-2 and CaCl\-2/H\-2O on the properties of polyacrylonitrile(PAN) ultrafiltration(UF) membranes prepared by phase inversion process was studied. The dissolving capacity of the casting solut...The effect of additives CaCl\-2 and CaCl\-2/H\-2O on the properties of polyacrylonitrile(PAN) ultrafiltration(UF) membranes prepared by phase inversion process was studied. The dissolving capacity of the casting solution for CaCl\-2 was enhanced by the addition of H\-2O. The membranes are characterized in terms of the pure water flux and molecular weight cut\|off(MWCO). The addition of CaCl\-2 or CaCl\-2/H\-2O to the casting solution increases the resulting membrane permeability.展开更多
基金supported by the National Natural Science Foundation of China(51978133,52100026,U20A20322,52170151,51978132)the Fundamental Research Funds for the Central Universities of China(2412021QD022)+1 种基金the Key Research and Development Project of Hainan Province(ZDYF2022SHFZ298)the Industrialization Cultivation Project of Jilin Provincial Department of Education(JJKH20221174CY)。
文摘The occurrence of ultrafiltration(UF)membrane fouling frequently hampers the sustainable advancement of UF technology.Reactive self-cleaning UF membranes can effectively alleviate the problem of membrane fouling.Nevertheless,the self-cleaning process may accelerate membrane aging.Addressing these concerns,we present an innovative design concept for composite self-healing materials based on self-cleaning UF membranes.To begin,TiO_(2)nanoparticles were incorporated into the polymer molecular structure via molecular design,resulting in the synthesis of TiO_(2)/carboxyl-polyether sulfone(PES)hybrid materials.Subsequently,the nonsolvent-induced phase inversion technique was employed to prepare a novel of UF membrane.Lastly,a polyvinyl alcohol(PVA)hydrogel coating was applied to the hybrid UF membrane surface to create PVA@TiO_(2)/carboxyl-PES self-healing reactive UF membranes.By establishing a covalent bond,the TiO_(2)nanoparticles were effectively and uniformly dispersed within the UF membrane,leading to exceptional self-cleaning properties.Furthermore,the water-absorbing and swelling properties of PVA hydrogel,along with its capacity to form hydrogen bonds with water molecules,resulted in UF membranes with improved hydrophilicity and active self-healing abilities.The results demonstrated that the water contact angle of PVA@5%TiO_(2)/carboxyl-PES UF membrane was 43.1°.Following a 1-h exposure to simulated solar exposure,the water flux recovery ratio increased from 48.16%to 81.03%.Moreover,even after undergoing five cycles of 12-h simulated sunlight exposure,the UF membranes exhibited a consistent retention rate of over 97%,thus fully demonstrating their exceptional self-cleaning,antifouling,and selfhealing capabilities.We anticipate that the self-healing reactive UF membrane system will serve as a pioneering and comprehensive solution for the self-cleaning antifouling challenges encountered in UF membranes while also effectively mitigating the aging effects of reactive UF membranes.
文摘A non-solvent induced phase separation(NIPS)process was used to fabricate a series of sulfonated polyethersulfone(SPES)membranes blending with different concentrations of SBA-15-g-PSPA with the applications in the ultrafiltration(UF)process.SBA-15 was modified with 3-methacrylate-propyltrime thoxysilane(MPS)to form SBA-15-g-MPS.It was further modified with the charge tailorable polymer chains by reacting with 3-sulfopropyl methacrylate potassium salt.The nanoparticles were uniformly dispersed and finger-like channels were developed within the membrane.The adding of surface modified SBA-15-g-PSPA nanoparticles has significantly improved membrane water permeability,hydrophilicity,and antifouling properties.The pure water fluxes of the composite SPES membranes were significantly higher than the pristine SPES membrane.For the membrane containing 5%(mass)of SBA-15-g-PSPA(MSSPA5),the pure water flux was increased dramatically to 402.15 Lm^(-2)·h^(-1),which is ~1.5 times that of MSSPA0(268.0 Lm^(-2)·h^(-1)).The high flux rate was achieved with 3%(mass)of SBA-15 nanoparticles with retained high rejection ratio 98%for natural organic matter.The results indicate that the fashioned composite membrane comprising SBA-15-g-PSPA nanoparticles have a promising future in ultrafiltration applications.
基金Supported by the Natural Science Foundation of Shandong Province(Q2007B01)
文摘Membrane fouling is one of the major obstacles for reaching a high flux over a prolonged period of ultrafiltration(UF)process.In this study,a sulfonated-polyethersulfone(SPES)/nano-TiO2 composite UF membrane with good anti-fouling performance was fabricated by phase inversion and self-assembly methods.The TiO2 nanoparticle self-assembly on the SPES membrane surface was confirmed by X-ray photoelectron spectroscopy (XPS)and FT-IR spectrometer.The morphology and hydrophilicity were characterized by scanning electron microscopy(SEM),atomic force microscopy(AFM)and contact angle goniometer,respectively.The anti-fouling mechanism of composite UF membrane was discussed through the analysis of the micro-structure and component of UF membrane surface.The results showed that the TiO2 content and the micro-structure of the composite UF membrane surface had great influence on the separation and anti-fouling performance.
基金Financial support from the National Natural Science Foundation of China (21706119)the Program of Excellent Innovation Teams of Jiangsu Higher Education Institutions+1 种基金the Project of Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)the partial support by the Open Fund of State Key Laboratory of Separation Membranes and Membrane Process (M1-201702)。
文摘Polysulfone(PSF) is extensively used for the production of ultrafiltration(UF) membranes thanks to its high strength,chemical stability,and good processibility.However,PSF is intrinsically hydrophobic,and hydrophilic modification is always required to PSF-based membranes if they are intended to be used in aqueous systems.Facile strategies to prepare hydrophilic PSF membranes are thus highly demanded.Herein we spray coat a PSF-based amphiphilic block polymer onto macroporous substrates followed by selective swelling to prepare flat-sheet PSF UF membranes.The polymer is a triblock polymer containing PSF as the majority middle block tethered with shorter block of polyethylene glycol(PEG) on both ends,that is,PEG-b-PSF-b-PEG.We use the technique of spray coa ting to homogeneously dispense diluted triblock polymer solutions on the top of macroporous supports,instantly resulting in uniform,defect-free polymer coating layers with the thickness down to ~1.2 μm.The bi-layered composite structures are then immerged in ethanol/acetone mixture to generate mesoscale pores in the coating layers following the mechanism of selective swelling-induced pore generation,thus producing composite membranes with the mesoporous triblock polymer coating as the selective layers.This facile strategy is free from additional hydrophilic modification and much smaller dosages of polymers are used compared to conventional casting methods.The pore sizes,porositie s,hydrophilicity,and consequently the separation properties of the membranes can be flexibly tuned by changing the swelling duration and the composition of the swelling bath.This strategy combining spray coating and selective swelling is upscalable for the production of highperformance PSF UF membranes.
基金financially supported by the National Natural Science Foundation of China(52003266,21961160739)the Development of Scientific and Technological Project of the Jilin Province(YDZJ202101ZYTS162,20200801051GH)Chinese Academy of Sciences-Wego Group High-tech Research&Development。
文摘The past few decades have witnessed rapid gains in our demands of antifouling membranes such as water purification membranes and hemodialysis membranes.A variety of methodologies have been proposed for improving the antifouling performance and the hemocompatibility of the membranes.In this study,a series of copolymers(PSF-PESSB)containing polysulfone(PSF)and poly(arylene ether sulfone)bearing pendant zwitterionic sulfobetaine groups(PESSB)were prepared via one-pot polycondensation.Subsequently,the ultrafiltration(UF)membranes were prepared from different zwitterion-containing copolymers.The prepared membranes showed high thermal stability and mechanical properties.Besides,it also displayed attractive antifouling performance and blood compatibility.Compared with the original PSF membrane,the amount of protein absorption on the modified membrane was reduced;the flux recovery ratio and the resistance to blood cells were significantly improved.The results of this work suggest that PSF-PESSB membranes are expected to be applied in blood purification.The introduction of zwitterion-containing polymers to membranes paves ways for developing advanced hemodialysis technologies for crucial process.
基金supported by National Natural Science Foundation of Tianjin(18JCZDJC37200)Tianjin University of Science&Technology Innovation Fund(2014CXLG11)+2 种基金Tianjin Key Laboratory of Marine Resources and Chemistry(201404)Yangtze Scholars and Innovative Research Team in University(IRT-17R81)Innovative Research Team of Tianjin Municipal Education Commission(TD13-5008)。
文摘Polyphenylsulfone(PPSU)ultrafiltration membrane with different structures was prepared by nonsolvent-induced phase separation.The effects of coagulation bath conditions(concentration and temperature)on membrane morphology,pure water flux,pore size,porosity,and contact angle were studied and discussed based on ternary-phase diagrams.Results indicated that water had stronger coagulant power than ethanol,and that the morphology of the membrane prepared from the polyphenylsulfone/1-methyl-2-pyrrolidinone/H_(2)O(PPSU/NMP/H_(2)O)system had finger-like structures.Conversely,sponge-like structures were observed for the PPSU/NMP/(NMP-H_(2)O)and PPSU/NMP/(70 NMP-EtOH-H_(2)O)systems.Ethanol also greatly influenced on membrane structures.According to the Scanning electronic microscopy(SEM)image,the composition(mass fraction)of casting solution is 16%PPSU-84%NMP and the coagulation bath consisting of 70%NMP-26%H_(2)O-4%C_(2)H_(5)OH.Meanwhile,the PPSU ultrafiltration membrane with spong-like was prepared under 8℃coagulation bath.The formation of sponge-like structure reduces the pure water flux of ppsu membrane from 488.39 L·m^(-2)·h^(-1)to 36.04 L·m^(-2)·h^(-1).It also reduces the gas permeability,porosity,and pore size of the membrane.The addition of ethanol and NMP into the coagulation bath increases the roughness of the PPSU ultrafiltration membrane and reduces the hydrophilicity of the membrane.
文摘Polyethylene glycol(PEG) membranes with different molecular mass cut-offs were used to treat oil/water emulsion, and the effects of experimental conditions including pressure, temperature and different opera- ting modes on permeate flux and removal rate of chemical oxygen demand (COD_ Cr) were studied. The results show that the permeate flux of ultrafiltration membrane is influenced by pressure and temperature; practical pressure is chosen to be 0.30.7MPa for the PEG with molecular mass cut-offs of 8000 and 0.71.0 MPa for the PEG with molecular mass cut-offs of 2500; and the practical temperature is chosen to be 2532℃. Different operating modes of ultrafiltration also influence the permeate flux and removal rate of COD_ Cr. The ultrafiltration membrane of intermittent cross-flow operating mode is easier to be influenced by blocky polarization and contamination than that of sequential cross-flow operating mode. Removal rate of COD_ Cr in intermittent cross-flow and sequential cross-flow condition can be maintained at about 93%.
基金Supported by the National Natural Science Foundation of China(No.81503258,No.81373980)Youth Natural Science Foundation of Jiangsu Province(No.BK20151005)Science and Technology Project of Jiangsu Traditional Chinese Medicine Administration(No.YB2015009)
文摘With the rapid increase of water contamination,membrane separation technology and their corresponding molecular weight cut-off(MWCO) evaluation method become more necessary.In this study,Panax notoginseng saponins was used as a new standard marker to determinate ultrafiltration(UF) membrane MWCOs,series of Millipore membranes were selected as control group to analyze and calculate the relationship between retention rate and MWCOs with exponential or logarithmic equation.A new and convenient method was provided for determining the membrane MWCO by modeling analysis retention rate with MWCOs,and the regression coefficients >0.990.The feasibility and practicability of established method was verified by different manufactures' membrane and dextrans.In the detection progress,as the main ingredient of Panax notoginseng saponins,Notoginsenoside R_1,Ginsenoside Rg_1,Ginsenoside Rb_1 and Ginsenoside Rd with different surface activity,the MWCO range of UF membranes can be divided into two zones mainly due to the retention rate difference among Notoginsenoside R_1,Ginsenoside Rg_1,Ginsenoside Rb_1 and Ginsenoside Rd.Zone 1,1000-10000;and Zone II,10000-100000.Thus,the new method would be helpful to improve the applicability of UF membrane in separation technology.
文摘Broadly speaking, this study aims to develop "batik" dyes wastewater treatment technologies by hybrid process that combines Fenton oxidation and separation using ultrafiltration membranes. Specifically, the purpose of this study was to determine the effect of membrane characteristics, feed solution pH, operating pressure of "Dead-end" membrane reactor, and the frequency of membranes which uses on the percentage of COD reduction in "batik" wastewater. In this study, the filtrate from wastewater pre-treatment with Fenton oxidation, both without and with addition of activated carbon, is passed to the ultrafiltration (UF) separation system. Fenton oxidation process was carried out at optimum conditions, i.e. at pH 3, temperature 50 ℃, and the addition FeSO4·7H2O and H2O2 at 747-830 mg/L and 1,168-1,460 mg/L, respectively. The optimum reduction percentage of COD can be achieved when the membranes used for separation has a pore size of 0.01 to 0.015 lam, feed solution pH 2, operating pressure 1 atm and frequency of membranes uses I x. To determine the fouling potential on ultrafiltration membranes that are used, flux measurements were performed 3 times for each membrane. These stages can see that the flux decline reached 22.5% when the effluent filtered directly to the membrane; 17.3% when performed pre-treatment prior to separation processes using membranes and 10% when combined pre-treatment process, use of activated carbon and the separation using ultrafiltration membranes.
基金This work was financially supported by the National Natural Science Foundation of China(Grant Nos.22278318 and 21878230).
文摘Various hydrophilic poly(ethylene-co-vinyl alcohol)(EVOH)were used herein to precisely control the structure and hydrodynamic properties of polysulfone(PSF)membranes.Particularly,to prepare pristine PSF and PSF/EVOH blends with increasing vinyl alcohol(VOH:73%,68%,56%),the non-solvent-induced phase separation(NIPS)technique was used.Polyethylene glycol was used as a compatibilizer and as a porogen in N,Ndimethylacetamide.Rheological and ultrasonic separation kinetic measurements were also carried out to develop an ultrafiltration membrane mechanism.The extracted membrane properties and filtration capabilities were systematically compared to the proposed mechanism.Accordingly,the addition of EVOH led to an increase in the rheology of the dopes.The resulting membranes exhibited a microporous structure,while the finger-like structures became more evident with increasing VOH content.The PSF/EVOH behavior was changed from immediate to delayed segregation due to a change in the hydrodynamic kinetics.Interestingly,the PSF/EVOH32 membranes showed high hydrophilicity and achieved a pure water permeability of 264 L·m^(–2)·h^(–1)·bar^(–1),which was higher than that of pure PSF membranes(171 L·m^(–2)·h^(–1)·bar^(–1)).In addition,PSF/EVOH32 rejected bovine serum albumin at a high rate(>90%)and achieved a significant restoration of permeability.Finally,from the thermodynamic and hydrodynamic results,valuable insights into the selection of hydrophilic copolymers were provided to tailor the membrane structure while improving both the permeability and antifouling performance.
基金supported by the National Key R&D Program of China(No.2016YFC0400802)the National Natural Science Foundation of China(No.51290282)the “National Water Pollution Control and Treatment Science and Technology Major Project(No.2015ZX07406006).”
文摘Pre-oxidation is widely used to reduce ultrafiltration membrane fouling. However, the variation in the composition of microbial communities and extracellular polymeric substances (EPSs) accompanying pre-oxidation in drinking water treatment has received little attention. In this study, hydrogen peroxide (H2O2) was used in a coagulation- ultrafiltration process with Al2(SO4)3.18H2O. A long-term reactor experiment (60 d) showed that pre-oxidation alleviated membrane fouling, mainly due to its inhibition of microbial growth, as observed by flow cytometry measurements of the membrane tank water. Further analysis of the formed cake layer demonstrated that the corresponding levels of EPS released from the microbes were lower with than without H202 treatment. In comparison to polysaccharides, proteins dominated the EPS. 2D-electrophoresis showed little difference (p 〉 0.05, Student's t-test) in the composition of proteins in the cake layer between the treatments with and without H2O2. The molecular weights of proteins ranged from approximately 30-50 kDa and the majority of isoelectric points ranged from 6 to 8. Highthroughput sequencing showed that the predominant bacteria were Proteobacteria, Bacteroidetes, and Verrucomicrobia in both cake layers. However, the relative abundance of Planctomycetes was higher in the cake layer with H2O2 pre-oxidation, which was likely probably due to the strong oxidative resistance of its cell wall. Overall, our findings clarify the fundamental molecular mechanism in H2O2 pre-oxidation for ultrafiltration membrane bio-fouling alleviation in drinking water treatment.
文摘Membrane fouling has been investigated by using a polysulfone ultrafiltration membrane with the molecular weight cutoff of 20 kDa to treat crushed coal pressurized gasification wastewater. Under the conditions of different feed pressures, the permeate flux declines and rejection coefficients of pollutants referring to three parameters (total organic carbon (TOC), chroma and turbidity) were studied. The membrane fouling mechanism was simulated with three classical membrane fouling models. The membrane image and pollutants were analyzed by scanning electron microscopy and gas chromatography-mass spectrography (GC-MS). The results indicate that the permeate flux decreases with volume reduction factor before reaching a constant value. The rejection coefficients were also measured: fTOC = 70.5%,fc = 84.9% andfa- = 91%. Further analysis shows that the higher the feed pressure is, the sooner the permeate flux reaches constant value and the more sharply the permeate flux declines. Constant flux indicates a nonlinear growth with feed pressure (PF): when Pr equals 1.2 bar, the mark for the critical flux, slight membrane fouling occurs; when PF exceeds 1.2 bar, cake layer pollution aggravates. Also the rejection coefficients of global pollutant increases slightly with PF, suggesting the possibility of cake compression when PF exceeds 1.2 bar. Through regression analysis, the fouling of polysulfone ultrafiltration membrane could be fitted very well by cake filtration model. The membrane pollutants were identified as phthalate esters and long-chain alkenes by GC-MS, and a certain amount of inorganic pollutants by X-ray photoelectron spectroscopy.
基金financial support under Heilongjiang Postdoctoral Fund (No.LBH-Z09175)
文摘Novel poly(aryl ether sulfone ketone)s (PAESK) were synthesized from bisphenol A (BPA), 9,9'-bis(4-hydroxyphenyl) fluorene (BHPF), 4,4'-dichlorodiphenylsulfone (DCS) and 4,4'-difluorobenzophenone (DFB) via nucleophilic substitution polymerization, which were subsequently used to fabricate ultrafiltration membrane by phase-inversion method for high temperature condensed water treatment. The obtained high molecular weight co-polymers with fluorene group with good solubility and good thermal stability, can be easily cast into flexible, white and non-transparent fiat films. The influence of molar ratio of BPA and BHPF on the properties of the prepared co-polymers and membranes was investigated in detail. SEM study of the morphology of the membranes indicated that the prepared membranes possessed homogeneous pores on the top surface and were sponge-like or finger-like in cross-section. Pure water flux of the membranes increased from 71.87 L·m-2.h-1 to 247.65 L·m-2.h-1, while the retention of BSA decreased slightly, and the water contact angle decreased from 82.1 ° to 55.6° with the PVP concentration from 0 wt% to 10 wt%. With increasing concentration of PVP, the mechanical properties of membranes decreased, while the thermal stability increased. The permeate flux measurement showed that the PAESK membrane had the potential for high temperature condensed water treatment.
文摘The sensitivity of poly(arylsulfone)(PSf) for UV irradiation in different solvents(water and ethanol) was investigated. It is confirmed that acrylic acid(AA) and acrylamide(AAm) are grafted only onto the surface of the membrane instead of the interior by FTIR and scanning electron microscope(SEM). The membrane performance(Δ J/J 0 and contact angle θ ) after photografting was studied. In the range of conditions used, the grafting yield increases with irradiation time and monomer concentration growing. After photografting and N 3 dimethyl aminopropyl N' ethycarbodiimide hydrochloride(EDC) activation, PSf membrane was immobilized with hydrogen peroxide oxidoreductase, and showed a higher activity than the control membrane.
基金supported by a major program granted by the National Natural Science Foundation of China(No.51290282)
文摘Coagulation plays an important role in alleviating membrane fouling, and a noticeable problem is the development of microorganisms after long-time operation, which gradually secrete extracellular polymeric substances(EPS). To date, few studies have paid attention to the behavior of microorganisms in drinking water treatment with ultrafiltration(UF)membranes. Herein, the membrane biofouling was investigated with different aluminum and iron salts. We found that Al_2(SO_4)_3·18 H_2O performed better in reducing membrane fouling due to the slower growth rate of microorganisms. In comparison to Al_2(SO_4)_3·18H_2O,more EPS were induced with Fe_2(SO_4)_3·x18H_2O, both in the membrane tank and the sludge on the cake layer. We also found that bacteria were the major microorganisms, of which the concentration was much higher than those of fungi and archaea. Further analyses showed that Proteobacteria was dominant in bacterial communities, which caused severe membrane fouling by forming a biofilm, especially for Fe_2(SO_4)_3·x18H_2O. Additionally, the abundances of Bacteroidetes and Verrucomicrobia were relatively higher in the presence of Al_2(SO_4)_3·18 H_2O,resulting in less severe biofouling by effectively degrading the protein and polysaccharide in EPS. As a result, in terms of microorganism behaviors, Al-based salts should be given preference as coagulants during actual operations.
基金supported by the National Natural Science Foundation of China (No. 51308146)the Program for New Century Excellent Talents in University (No. NCET-13-0169)+2 种基金the China Postdoctoral Science Foundation funded project (No. 2015T80360)the Heilongjiang Postdoctoral Fund (No. LBH-Z13083)the Open Project of State Key Laboratory of Urban Water Resource and Environment (No. ES201511-02)
文摘As a routine measurement to alleviate membrane fouling, hydraulic cleaning is of great significance for the steady operation of ultrafiltration(UF) systems in water treatment processes. In this work, a comparative study was performed to investigate the effects of the composition of backwash water on the hydraulic cleaning performance of UF membranes fouled by humic acid(HA). Various types of backwash water, including UF permeate, Milli-Q water, Na Cl solution, CaCl_2 solution and HA solution, were compared in terms of hydraulically irreversible fouling index, total surface tension and residual HA. The results indicated that Milli-Q water backwash was superior to UF permeate backwash in cleaning HA-fouled membranes, and the backwash water containing Na+or HA outperformed Milli-Q water in alleviating HA fouling. On the contrary, the presence of Ca^(2+) in backwash water significantly decreased the backwash efficiency. Moreover, Ca^(2+) played an important role in foulant removal, and the residual HA content closely related to the residual Ca^(2+) content.Mechanism analysis suggested that the backwash process may involve fouling layer swelling, ion exchange, electric double layer release and competitive complexation. Ion exchange and competitive complexation played significant roles in the efficient hydraulic cleaning associated with Na+and HA, respectively.
基金supported by the National Natural Science Foundation of China(No.51608427)the Natural Science Foundation of Shaanxi Province(No.2020JQ-672)+1 种基金the Key Research and Development Program of Shaanxi province(No.2019ZDLSF06-01)the Youth Innovation Team of Shaanxi Universities Funded by Education Department of Shaanxi Province。
文摘Sodium hypochlorite(NaClO)is a commonly applied cleaning agent for ultrafiltration membranes in water and wastewater treatment.Long-term exposure to NaClO might change the properties and performance of polymeric membranes,and ultimately shorten membrane lifespan.Active species in NaClO solution vary with solution pH,and the aging effects can change depending on the membrane material.In this study,the aging of polyvinylidene fluoride(PVDF)and polyethersulfone(PES)membranes by NaClO at pH 3–11 was investigated by examining variations in chemical composition,surface charge,surface morphology,mechanical strength,permeability,and retention ability.Polyvinyl pyrrolidone(PVP),which was blended in both membranes,was oxidized and dislodged due to NaClO aging at all investigated pH values,but the oxidation products and dislodgement ratio of PVP varied with solution pH.For the PVDF membrane,NaClO aging at pH 3–11 caused a moderate increase in permeability and decreased retention due to the oxidation and release of PVP.The tensile strength decreased only at pH 11 because of the defluorination of PVDF molecules.For the PES membrane,NaClO aging at all investigated pH resulted in chain scission of PES molecules,which was favored at pH 7 and 9,potentially due to the formation of free radicals.Therefore,a decrease in tensile strength and retention ability,as well as an increase in permeability,occurred in the PES membrane for NaClO aging at pH 3–11.Overall,the results can provide a basis for selecting chemical cleaning conditions for PVDF and PES membranes.
基金This work was supported by the National Natural Science Foundation of China(Nos.11875313,12075153,and 11575277).
文摘Membrane fouling is always the biggest problem in the practice of membrane separation technologies,which strongly impacts their applicability,separation efficiency,cost effectiveness,and service lifespan.Herein,a simple but effective 3D modification approach was designed for permanently functionalizing polymeric membranes by directly cross-linking polyvinyl alcohol(PVA)under gamma-ray irradiation at room temperature without any additives.After the modification,a PVA layer was constructed on the membrane surface and the pore inner surface of polyvinylidene fluoride(PVDF)membranes.This endowed them with good hydrophilicity,low adsorption of protein model foulants,and easy recoverability properties.In addition,the pore size and distribution were customized by controlling the PVA concentration,which enhanced the rejection ability of the resultant membranes and converted them from microfiltration to ultrafiltration.The crosslinked PVA layer was equipped with the resultant membranes with good resistance to chemical cleaning by acidic,alkaline,and oxidative reagents,which could greatly prolong the membrane service lifetime.Furthermore,this approach was demonstrated as a universal method to modify PVDF membranes with other hydrophilic macromolecular modifiers,including polyethylene glycol,sodium alginate,and polyvinyl pyrrolidone.This modification of the membranes effectively endowed them with good hydrophilicity and antifouling properties,as expected.
基金financially supported by the Postdoctoral Fellowship N°3190683 of Dr.Adrián González-Munoz from the Chilean Agencia Nacional de Investigación y Desarrollo(ANID)the Natural Sciences and Engineering Research Council of Canada(NSERC)Discovery Grant Program(Grant SD RGPIN-2018-04128 of Prof.Laurent Bazinet)。
文摘Processing bioactive peptides from natural sources using electrodialysis with ultrafiltration membranes(EDUF)have gained attention since it can fractionate in terms of their charge and molecular weight.Quinoa is a pseudo-cereal highlighted by its high protein content,amino acid profile and adapting growing conditions.The present work aimed at the production of quinoa peptides through fractionation using EDUF and to test the fractions according to antihypertensive and antidiabetic activity.Experimental data showed the production of peptides ranging between 0.4 and 1.5 k Da.Cationic(CQPF)(3.01%),anionic(AQPF)(1.18%)and the electrically neutral fraction quinoa protein hydrolysate(QPH)-EDUF(~95%)were obtained.In-vitro studies showed the highest glucose uptake modulation in L6 cell skeletal myoblasts in presence of QPH-EDUF and AQPF(17%and 11%)indicating potential antidiabetic activity.The antihypertensive effect studied in-vivo in spontaneously hypertensive rats(SHR),showed a decrease in systolic blood pressure in presence of the fractionated peptides,being 100 mg/kg a dose comparable to Captopril(positive control).These results contribute to the current knowledge of bioactive peptides from quinoa by reporting the relevance of EDUF as tool to produce selected peptide fractions.Nevertheless,further characterization is needed towards peptide sequencing,their respective role in the metabolism and scaling-up production using EDUF.
文摘The effect of additives CaCl\-2 and CaCl\-2/H\-2O on the properties of polyacrylonitrile(PAN) ultrafiltration(UF) membranes prepared by phase inversion process was studied. The dissolving capacity of the casting solution for CaCl\-2 was enhanced by the addition of H\-2O. The membranes are characterized in terms of the pure water flux and molecular weight cut\|off(MWCO). The addition of CaCl\-2 or CaCl\-2/H\-2O to the casting solution increases the resulting membrane permeability.