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A high-flux and stable poly(vinylidene fluoride) (PVDF) membrane that is also produced in a green method is particularly promising for membrane distillation (MD). In this work, a facile co-casting method was employed to fabricate porous PVDF membranes by using green solvent (PolarClean) and green casting fluids, including Acetyl tributyl citrate (ATBC) and polyethylene glycol 400 (PEG 400). During the co-casting process, ATBC or PEG was functioned as isolation layer to avoid rapid solvent/non-solvent exchange rate that could result in a dense membrane surface. The resulting top PVDF membrane surfaces were both highly porous during the phase inversion process after being cast by ATBC or PEG. In addition, the bottom surfaces were highly porous when using non-woven fabrics (NWFs) as casting supports whatever the PVDF concentrations were. It is worth mentioning that when the PVDF concentrations were below 20 wt%, the NWFs combined with PVDF membrane well that also provided a super-high mechanical strength for PVDF membranes. When the PVDF concentrations were above 25 wt%, the NWFs were detached from the PVDF membrane. Therefore, two kinds of PVDF membranes (with and without NWFs) could be produced. The optimized PVDF membranes with contact angle of above 120° showed above 99.99% and 99.9% rejection for saline water and ginseng extract during the MD process with a highest flux of ∼37 kgm−2h−1. This work provides a green and high-flux PVDF membrane for saline water and food extract in chemical industries. [Display omitted] • Porous top PVDF membrane surface was fabricated by using co-casting method. • Non-woven fabrics enabled highly porous bottom PVDF membrane surface. • All the solvents and casting fluids in the membrane formation were green. • PVDF/non-woven fabric membranes showed an ultra-high tensile strength of >50 MPa. • The membranes showed high rejection and flux for saline water and ginseng extract. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF) membranes are widely used in microfiltration and ultrafiltration processes for their excellent mechanical and chemical resistance and thermal stability in comparison with other polymeric membranes. Non-solvent induced phase separation (NIPS) is the most important method by which the PVDF membranes are prepared. The structure of the membranes prepared by NIPS method depends on different parameters including the concentration of the polymer solution, polymer molecular weight, the composition and temperature of coagulation bath, type of solvent and the presence of additives in the initial solution. In the present work, the effects of coagulation bath temperature and LiCl content of the dope solution were studied with respect to the structure and performance of PVDF membranes. N-Methyl-2-pyrrolidone and water were used as solvent and coagulation bath, respectively. A set of analytical techniques including: scanning electron microscopy, mechanical test, pure water permeability and mean pore radius of pores was used to characterize the membranes. Moreover, the separation of humic acid, a main biological contaminant in surface water resources, was studied to determine membranes performance. The results show that at constant coagulation bath temperature, presence of LiCl in the dope solution increased the number as well as the mean pore radius of the pores at the surface of membranes and consequently, pure water permeability of the membranes was increased, whereas, the mechanical strength and humic acid rejection of the membranes were dropped. Moreover, at a constant content of LiCl, increasing the coagulation bath temperature decreased the size of macrovoids so that the mechanical strength as well as humic acid rejection of the membranes was increased.

Abstract: Zwitterionic monomer carboxybetaine methacrylate (CBMA) is well known as an excellent hydrophilic and ion adsorption material. Herein, we created a PCBMA layer on PVDF membrane surface via physisorbed free radical polymerization grafting technique (P-FFPG) to improve its hydrophilicity, antifouling and inorganic salts separation property. The key factors of monomer concentration and reaction time which influence grafted density (GD) were investigated in the present work. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) confirmed that the CBMA monomer was grafted onto the membrane successfully. The surface chemistry composition was conducted via X-ray photoelectron spectroscopy (XPS). Scanning electron microscopy (SEM) analysis clearly showed that the PCBMA layer formed on the membrane surface, and its grafted degree increased with the monomer concentration. The water static contact measurement confirmed that modified PVDF membranes obtained stable enhanced hydrophilicity and superior water adsorption ability. The static protein adsorption at different pH showed a partly pH sensitivity and an improving antifouling ability almost in the whole pH range. The ultrafiltration experiments suggested that the anti-protein fouling of the grafted membranes was significantly improved. The modified membrane possessed a stable initial sodium chloride (NaCl) rejection ratio and reversible flux behavior. [Copyright &y& Elsevier]

Abstract: A facile surface self-assembled zwitterionization process is presented, aiming at improving the blood compatibility of poly(vinylidene fluoride) (PVDF) membranes. Zwitterionic diblock copolymers containing hydrophobic propylene oxide and hydrophilic sulfobetaine methacrylate blocks were prepared with well controlled molecular weights via atom-transfer radical polymerization (ATRP). Poly(propylene oxide)-block-poly(sulfobetaine methacrylate) (PPO-b-PSBMA) copolymers with varying zwitterionic PSBMA lengths were coated by self-assembling process onto the surface of PVDF microfiltration membranes in order to enhance their surface hydrophilicity and protein resistance. A systematic study regarding the effect of block lengths of PPO-b-PSBMA copolymers on the hemocompatibility of zwitterionic PVDF membranes in human blood solution was then performed. Protein adsorption from single-protein solutions and 100% blood plasma solutions was measured on the PVDF surfaces covered with PPO-b-PSBMA brushes. If the increase in PPO content in copolymer increased the efficiency of coating on the membrane, resistance to human fibrinogen adsorption was enhanced when increasing the PSBMA content. The control of the anchoring structures of zwitterionic copolymer layers highly regulates the adsorption of plasma proteins, the adhesion of platelets, and the coagulation of human plasma. PVDF membranes coated with PPO-b-PSBMA containing a high amount of zwitterionic SBMA units presented a high hydration capability, believed to allow improving significantly the hemocompatible character of PVDF membranes. This work suggests that the hemocompatible nature of self-assembled zwitterionic brushes gives them a great potential in the molecular design of antithrombogenic membranes for use in human blood applications. [Copyright &y& Elsevier]

Abstract: In this paper, the effects of high molecular weight additive (PEO-PPO-PEO), low molecular weight additive (oxalic acid) and inorganic additive (nano-TiO2) on PVDF membranes were studied by phase inversion method. The experimental results showed that the contact angle decreased as PEO-PPO-PEO was added in the casting solution. With the increasing concentration of PEO-PPO-PEO from 0.5 to 3.0 wt.%, the water flux increased from 0 to 1136L/m2h and the rejection decreased from 99.0% to 64.0%, meanwhile, the static contact angle stabilized basically around 66°. When the oxalic acid concentration increased from 0 to 3.0 wt.% and the concentration of PEO-PPO-PEO maintained at 0.5 wt.%, the water flux increased from 0 to 192L/m2h, while the rejection firstly decreased and then stabilized around 88.0%. Compared with PEO-PPO-PEO, PEO-PPO-PEO/nano-TiO2 and PEO-PPO-PEO/oxalic acid/nano-TiO2, the PVDF membrane with PEO-PPO-PEO/oxalic acid combined addition showed the best properties. As the concentrations of PEO-PPO-PEO and oxalic acid were 2.0 and 3.0 wt.% respectively, the water flux of PVDF membrane reached 2271L/m2h. [Copyright &y& Elsevier]

Abstract: This paper presents the energy evaluation of the cross-flow vacuum membrane distillation (VMD) for three types of lab-fabricated polyvinylidene fluoride (PVDF) membranes and the commercial Westran S PVDF membrane. Membranes with the effective area 23.5cm2 are tested with distilled water and geothermal water as the feed solutions. Results show that the membrane porosity controlled the flux through the fabricated membranes and the commercial membrane. The commercial membrane with porosity of approximately 76.5%, which was the most porous among the tested membranes, gave the highest flux at 9.28kg/m2 h under the optimum conditions of 33.2L/h feed flow rate and 30kPa downstream pressure. The corresponding specific energy consumption was 66.03kW/kgh−1 when distilled water was examined. Heating energy of 87–89kW/kgh−1, which is approximately 95% of the total energy consumption, could be saved when the warm geothermal water is fed directly into the VMD system. The water produced meets the drinking water quality with the TDS varying between 102 and 119ppm, thus the geothermal water desalination using the VMD system to produce the drinking water is satisfactory. An economic analysis for a 20,000m3/d VMD desalination plant finds that the water production costs are $0.50/m3 and $1.22/m3 respectively for the plant operated with and without geothermal energy (GE). Compare to the plant without GE utilisation, the water production costs of the plant operated with GE are less than $0.50/m3 that is at least $0.72/m3 or approximately 59% in cost saving when the water fluxes are larger than 6.6kg/m2 h. The specific membrane cost reduced from $0.058/m3 to $0.035/m3 when the membrane life extended from 3 to 5years. [Copyright &y& Elsevier]

Abstract: This study aims at developing an effective method to modify hydrophobic polyvinylidene fluoride (PVDF) membranes for membrane distillation (MD) which is tolerant to salty feed solution containing mineral oil. A novel approach was explored to obtain a highly hydrophilic membrane surface via plasma induced grafting of polyethylene glycol (PEG) and subsequent TiO2 particles deposition onto the membrane surface. The mechanism of oil affinity onto a membrane surface was quantitatively investigated by the extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) theory. A series of characterizations were conducted for the virgin and modified membranes. Membrane distillation tests for synthetic seawater containing 0.01wt% of mineral oil were also performed to investigate the influences of membrane hydrophobicity, membrane surface structure, pH value of the feed solution and hydrodynamic conditions on oil fouling behavior. The SEM and FTIR measurements confirmed the presence of PEG and TiO2 particles on the PVDF membrane substrate. The hydrophilically modified PVDF-PT membrane exhibits a positive interfacial free energy with oil in the feed, indicating the TiO2 deposition effectively improve the anti-fouling property of PVDF-P membrane and PVDF membrane. It was also found that the PVDF-PT membrane presents a stable water flux over 24h of operation without fouling and wetting due to combined effects of enhanced surface hydrophilicity and reduced membrane pore sizes. In addition, the pH value of the feed solution plays an important role in oil fouling. More severe fouling can be observed at the pH which made the membrane surface and oil droplets carry opposite charges. Moreover, a higher flow velocity enhances the shear force exerted on the oil droplets, thus leading to less oil present on the membrane surface and less oil fouling of the membrane. [Copyright &y& Elsevier]

Biofouling of membrane surfaces by the attachment of microorganisms is one of the major obstacles for ensuring the effectiveness of membrane separation processes. This work presents the construction of a zwitterionic PVDF membrane surface with improved resistance to biofouling. An amphiphilic copolymer of poly(vinylidene fluoride)-graft-poly(N,N-dimethylamino-2-ethylmethacrylate) (PVDF-g-PDMAEMA) was first synthesizedviaradical graft copolymerization and then the flat membrane was cast with immersed phase inversion. The PDMAEMA side chains tended to aggregate on the membrane surface, pore surface and internal pore channel surface, and were converted with 1,3-propane sultone (1,3-PS) to yield a zwitterionic membrane surface. A higher conversion of PDMAEMA chains and distribution of zwitterions were obtained using a longer treatment time. A biofouling assay indicated that incorporation of zwitterions suppressed the adsorption of extracellar polymer substances and the adhesion ofEscherichia colibacterial cells to the membrane surface, endowing the membrane with a high flux recovery and biofouling resistance in the filtration process. [ABSTRACT FROM PUBLISHER]

Abstract: In this work, a modified direct contact membrane distillation (MDCMD) with receiving solution in permeate was developed for accelerating ammonia removal from aqueous solution. The ammonia removal efficiency by means of DCMD, hollow fiber membrane contactor (HFMC) and MDCMD was comparatively investigated. And the effect of feed pH, temperature, flow rate and concentration on ammonia removal efficiency and the permeate flux in MDCMD process was studied. Experimental results showed that the ammonia removal efficiency of DCMD, HMC and MDCMD was 52%, 88% and 99.5% within 105min, respectively. In MDCMD, feed pH value was proved to be the most dominant factor and the optimal feed pH was 12.20. Increasing feed temperature and flow rate led to higher ammonia mass transfer coefficient, ammonia removal efficiency and permeate flux within the range studied. The initial ammonia concentration had a negligible effect on ammonia removal efficiency. [Copyright &y& Elsevier]

In this study, temperature-sensitive membranes were prepared by phase transition of the mixture of the temperature-sensitive poly( N-isopropylacrylamides) (PNIPAAM) microgels and poly(vinylidene fluoride). The results of Fourier transformed infrared spectrometer, X-ray photoelectron spectroscopy, elemental analysis, and scanning electron microscope photographs indicate that the PNIPAAM microgels are distributed more in the inner membrane than on the surface. The scanning electron microscope photographs reveal the blend membranes having porous surfaces with nanometer sizes and porous cross-sections with micrometer sizes. The addition of the PNIPAAM microgels is found to improve the porosity, the pore size, water flux, as well as to enhance the hydrophilicity and anti-fouling property of the blend membranes. The blend membrane shows temperature-sensitive permeability and protein rejection with the most dramatic change at around 32 °C which is the lower critical solution temperature of PNIPAAM, when water or bovine serum albumin solution flow through. Specifically, below 32 °C, the blend membrane shows a high protein rejection ratio which decreases with increasing temperature and a low water flux which increases with increasing temperature; above 32 °C, the blend membrane shows a low protein rejection ratio which decreases with increasing temperature and a high water flux which increases with increasing temperature. [ABSTRACT FROM AUTHOR]

Abstract: Membrane fouling remains one of the most problematic issues surrounding membrane use in water and wastewater treatment. Organic fouling and biological fouling contribute to irreversible fouling and flux decline in these processes. In this study, to obtain both organic antifouling and antibacterial properties, in situ formed Ag nanoparticles were immobilized in poly (vinylidene fluoride) (PVDF) ultrafiltration (UF) membranes, using N,N-dimethylformamide (DMF) as the reducing agent for Ag+ and solvent for PVDF polymer simultaneously. The hydrophilicity of the membrane surface was improved by the integration of Ag nanoparticles, leading to a reduction in membrane contact angle (81 to 68°) and an increase in permeate flux (36.4 to 108.6L/m2 h). The organic antifouling and antibacterial performance of the Ag-loading membranes were evaluated by using bovine serum albumin (BSA) aqueous solution and Escherichia coli (E. coli) as model foulants, respectively. The experimental results confirm that the immobilization of Ag nanoparticles in PVDF UF membrane can mitigate the organic and biological fouling. [Copyright &y& Elsevier]

The assessment of collagen content in tissues is important in biomedical research, since this protein is altered in numerous diseases. Hydroxyproline and Sirius red based assays are the most common methods for collagen quantification. However, these procedures have some pitfalls, such as the requirement of oxygen-free medium or expensive equipment and large sample size or being unsuitable for hydrolyzed collagen, respectively. Our objective was to develop a specific, versatile, and user-friendly quantitative method applicable to small tissue samples and extracts obtained from elastin purification, therefore, suitable for simultaneous quantification of elastin. This method is based on the binding of Sirius red to collagen present in a sample immobilized on a PVDF membrane, as in the dot-blot technique, and quantified by a scanner and image analysis software. Sample loading, Sirius red concentration, temperature and incubation time, type of standard substance, albumin interference, and quantification time are optimized. The method enabled the quantification of (1) intact collagen in several rat tissue homogenates, including small resistance-sized arteries, (2) partially hydrolyzed collagen obtained from NaOH extracts, compatible with elastin purification, and (3) for the detection of differences in collagen content between hypertensive and normotensive rats. We conclude that the developed technique can be widely used since it is versatile (quantifies intact and hydrolyzed collagen), requires small sample volumes, is user-friendly (low-cost, easy to use, minimum toxic materials, and reduced time of test), and is specific (minimal interference with serum albumin). [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: PVDF microfiltration membranes were modified by γ-ray irradiation induced grafting polymerization of 4-vinyl pyridine (4-VP) and then quaternization by n-butyl chloride. The effects of grafting method (simultaneous irradiation, pre-irradiation/UV), grafting conditions (absorbed dose, UV irradiation time, and 4-VP concentration) and quaternization conditions (temperature, time, and concentration of n-butyl chloride) were investigated. It was found that, the grafting degree initially increases with the absorbed dose and then reaches a plateau. The optimal concentration of 4-VP is around 15wt.%. The ion exchange capacity increases with quaternization temperature, time, and concentration of n-butyl chloride. After modification, the pores size, permeation flux, as well as elongation at break, of quaternized membrane decreases, while the retention coefficient, tensile strength and Young’s modulus increase apparently. Upon contacting with the membranes, the Escherichia coli concentration decreases gradually. It is the adsorption mechanism for the pristine membranes whereas contact-killing mechanism for the quaternized membranes. Simultaneous irradiation is more effective than pre-irradiation/UV in the improvement of antibacterial property of membranes. [Copyright &y& Elsevier]

Abstract: Conducting polymer actuators such as polypyrrole (PPy) microactuators are interesting candidates to drive autonomous microrobotic devices that require low weight and low power. Simple PPy tri-layer bending type microactuators that operate in air have been demonstrated previously but they lack individual control and had problems with short circuiting due to electrical connections. The lack of micropatterning methods and proper interfacing are currently major obstacles in the development of PPy tri-layer microactuators. Here, we report for the first time methods for successfully patterning and interfacing of such tri-layer PPy microactuators. The PPy tri-layer actuators were patterned using adapted microfabrication technology including photolithography. The interface was based on a flexible printed circuit board comprising the electronic circuit into which the actuator unit was embedded. It showed that the microfabricated tri-layer actuators functioned as good as the normally fabricated actuators. The new interface seemed to actually improve the actuator performance. This interfacing method could also be applied to other electroactive polymer devices, such as ion polymer metal composites (IPMC) and dielectric elastomers (DE). [Copyright &y& Elsevier]

A novel method for the surface modification of PVDF porous membranes was introduced. Styrene-( N-(4-hydroxyphenyl) maleimide) alternating copolymer SHMI-Br was blended with PVDF to fabricate SHMI-Br/PVDF membranes. The C-Br bond on the SHMI-Br/PVDF membrane was served as initial site of ATRP, and P(PEGMA) brush was grafted on the PVDF membrane. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR/FTIR) was used to prove the P(PEGMA) brushes were successfully grafted onto the SHMI-Br/PVDF membrane surface. Introduction of P(PEGMA) brushes on the PVDF membrane surface enhanced the hydrophilicity effectively. When the PEGMA degree of grafting was 16.7 wt%, the initial contact angle of PVDF membrane decreased from 98° to 42°. The anti-fouling ability of PVDF membrane was improved significantly after P(PEGMA) brush was grafted. Taking the PEGMA degree of grafting 16.7 wt% as an example, the flux of protein solution was about 151.21 L/(m h) when the pH value of the BSA solution was 4.9. As the pH value was increased to 7.4, the flux was changed to 180.06 L/(m h). However, the protein solution flux of membrane M3 (PEGMA: 0 wt%) was only 73.84 L/(m h) and 113.52 L/(m h) at pH 4.9 and 7.4, respectively. [ABSTRACT FROM AUTHOR]

Abstract: PVDF microfiltration membranes were modified by photografting of 4-vinylpyridine and then quaternized with n-butyl chloride. Lysozyme was employed as a model alkaline protein to investigate the antifouling performance of quaternized membranes. The effects of grafting and quaternization conditions on modification were studied. The results show that, the percent of initiator grafted and grafting density increase with the irradiation time, whereas the grafted chain length and grafting degree rise initially and then reach plateau. The optimal concentrations of initiator and 4-vinylpyridine are 5wt.% and 20wt.%, respectively. The ion exchange capacity increases with quaternization temperature and time, and the optimal concentration of n-butyl chloride is 30wt.%. When the solution pH is at the isoelectric point of lysozyme, the saturated adsorption capacity of membranes reaches maximum. When the solution pH is lower than isoelectric point, the saturated adsorption capacity of quaternized membranes is the lowest due to electrostatic repulsion and hydrophilicity of membranes. The modified membranes exhibit excellent antifouling performance to alkaline proteins. [Copyright &y& Elsevier]

Abstract: Polyvinylidene fluoride (PVDF) membranes were prepared via the phase inversion method. The focus of this paper was put on the effects of four specific solvents with different solubility power including hexamethylphosphoramide (HMPA), trimethylphosphate (TMP), N,N-dimethylformamide (DMF) and triethylphosphate (TEP) on membrane polymorphism. Polymorphism of PVDF membranes was analyzed by wide-angle X-ray diffraction (WAXD), Fourier transform infrared spectroscopy (FTIR), Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) respectively. All results revealed that the dissolution of PVDF in different solvents had a great influence on the membrane crystalline phase. The well dissolved PVDF solution tended to form α phase during phase inversion process while the poorly dissolved PVDF solution favored the formation of β phase. Furthermore, a soft coagulation bath was used during the phase inversion process to enhance the filtration permeability of the PVDF membranes. The fouling resistance to protein and mechanical properties of the membranes were also investigated. [Copyright &y& Elsevier]

Abstract: Pd/Fe nanoparticles being used for catalytic dechlorination were immobilized in hydrophilically modified poly(vinylidene fluoride) (PVDF) microfiltration membrane for the purpose of decreasing the aggregation of Pd/Fe nanoparticles. Effective preservation and regeneration methods of Pd/Fe-based PVDF membrane were also developed. The pristine and modified membranes were systematically characterized in terms of morphologies (SEM), particle distribution (TEM), surface metal composition (XPS), crystal structure (XRD), thermal stability (TGA), and hydrophilicity (water contact angle). Catalytic dechlorination activities of Pd/Fe nanoparticle-based hydrophilized and unhydrophilized PVDF membranes were comparatively studied by using trichloroacetic acid (TCAA) as target pollutant. The results indicate that hydrophilization process facilitated the even dispersion of nanoparticles inside the pores of PVDF membrane. The investigations on reaction kinetics indicate that the catalytic dechlorination rate of TCAA with Pd/Fe-based hydrophilized PVDF membrane was 6.8 times greater than that with Pd/Fe-based unhydrophilized PVDF membrane. [Copyright &y& Elsevier]

Abstract: The use of microfiltration (MF) or ultrafiltration (UF) prior to reverse osmosis (RO) process for reuse of reclaimed water is becoming increasingly attractive. In this work, a secondary municipal effluent was treated by a pilot-scale continuous filtration system with an innovative polyvinylidene fluoride (PVDF) MF membrane prepared via thermally induced phase separation (TIPS) method. The study showed that the MF system was operated under low normalized trans-membrane pressure (substantially below 40kPa) and high permeate flux (52–60L/m2/h). The MF system was able to treat the secondary effluent of unstable quality with good system stability. The membrane''s permeability was easily recovered by chemical enhanced backwash (CEB) at a low effective chorine concentration (300 or 500mg/L). The membrane exhibited excellent mechanical strength and strong chemical resistance throughout the investigation. The treated water from the MF system exhibited stable quality with turbidity less than 0.05NTU, 15-minute silt density index (SDI15) less than 3 and chemical oxygen demand (CODCr) less than 15mg/L. The treated water quality completely met the quality requirement of RO feed water. This work demonstrated the feasibility of using the innovative MF membrane prior to RO for reuse of the secondary municipal effluent. [Copyright &y& Elsevier]

Western blotting is a widely used technique for the detection and quantification of proteins and peptides. However, it is challenging to detect small peptides efficiently by the conventional Western blotting method with shaking, in part because the peptides readily detach from the blotted membrane. Although some modified Western blotting protocols have been developed to overcome this problem, it remains difficult to prevent peptide detachment from the membrane. In this study, we show that the previously developed vacuum-assisted detection method greatly improves the detection of small peptides without additional protocol modification. The vacuum-assisted method was developed to shorten the time required for all immunodetection steps, and all the Western blotting solutions penetrated the membrane quickly and efficiently by this method. By using this vacuum method, we succeeded in detecting small peptides that were completely undetectable by the conventional Western blotting method. We also confirmed that peptide detachment was induced even by gentle shaking in the case of the conventional method, and the detachment was accelerated when detergent was present in the buffer. Unlike in the conventional method, there is no need to shake the membrane in solution in the vacuum method. Therefore, it is thought that the small peptides could be detected sensitively only by the vacuum method. [ABSTRACT FROM AUTHOR]

Abstract: Poly(vinylidene fluoride) (PVDF) membranes were prepared by an ultrasound assisted phase inversion process. The effect of ultrasonic intensity on the evolution of membrane morphology with and without the addition of pore former LiCl during precipitation process was comprehensively investigated. Besides the inter-diffusion between the solvent and nonsolvent, the ultrasonic cavitation was thought to have significant influences on phase inversion and the resultant membrane morphology. The mutual diffusion between water and solvent during the ultrasound assisted phase inversion process was measured. The crystalline structure was detected by wide angle X-ray diffractometer (WAXD). The thermal behavior was studied by differential scanning calorimeter (DSC). The mechanical strength, forward and reverse water flux, rejection to bovine serum albumin (BSA) and pepsin were also investigated. By the ultrasound assisted phase inversion method, ultra-filtration membrane was successfully prepared, which exhibited more preferable morphology, better mechanical property and more favorable permeability without sacrificing the rejection and thermal stability. [Copyright &y& Elsevier]

Abstract: It was the aim of this work to investigate equilibrium and thermodynamic aspects for static adsorption of bovine serum albumin (BSA) as model protein of extracellular polymer substances (EPS) from membrane bioreactor (MBR) on hydrophilic polyvinylidene fluoride (PVDF) microfiltration membrane. In present paper, the influences of temperature, pH and ionic strength were studied and eight different isotherm models were used to fit equilibrium data by nonlinear regression method. The obtained results showed that the best-fitted adsorption isotherm models were in the order of: Langmuir and Freundlich>BET>Langmuir≈Redlich–Peterson≈Temkin>Freundlich>Fowler and Guggenheim (Hill–De Boer), of which, Langmuir–Freundlich isotherm is the best suitable. Thermodynamic investigation indicated that this process was not spontaneous and endothermic and maybe attributed to physicosorption, and the distribution of BSA adsorbed on PVDF membrane was more chaotic than that in the aqueous solution. The results from the static adsorption of BSA on PVDF membrane can be a useful tool to evaluate the behavior of membrane biofouling in MBR and also provide basis for performance comparison among different membranes. [Copyright &y& Elsevier]

Abstract: Highly constrained by the requirements of high porosity and large pore sizes, traditional single-bore hollow fiber membranes often suffer from easy breakage and performance instability during long-term operations of membrane distillation (MD). In this work, a multi-bore PVDF hollow fiber (MBF) membrane with a lotus root-like geometry was designed and successfully fabricated via the specially designed spinneret and optimized spinning conditions. Various effects of spinning parameters including bore flowrate, dope flowrate and take-up speed were investigated on the membrane macro- and micro-structure, mechanical properties and direct contact membrane distillation (DCMD) performance. The tensile strength characterizations have proven the excellent mechanical rigidity and elasticity of MBF membranes. Even for the MBF membrane with a thin wall of around 40μm, the maximum load was as high as 2.4N. Most importantly, the performance of the DCMD of the MBF membrane was only slightly lower or even comparable to that of single-bore membranes. In addition, the MBF membranes exhibited superior stability in terms of vapor permeation flux and salt rejection during the continuous DCMD experiment with robust operational conditions. We believe this work may have profound implication to the development of mechanically durable membranes not only for membrane distillation MD but also for other membrane applications. [Copyright &y& Elsevier]

Abstract: Effect of quenching temperature on the morphological and crystalline properties of PVDF and PVDF–TiO2 hybrid membranes was studied. PVDF and PVDF–TiO2 hybrid membranes were prepared via thermally induced phase separation (TIPS). The membranes were characterized by scanning electron microscopy, differential scanning calorimetry and X-ray diffraction. Results showed the blends underwent solid–liquid (S–L) phase separation when quenching temperature was below onset crystallization temperature and the size of spherulities and interspherulite microvoids increased with the increase of the quenching temperature. Spherulities became more regular at higher quenching temperature. The crystallinity (X c) of neat PVDF membranes decreased with the increase of quenching temperatures while the X c of hybrid membranes decreased first, then increased. Spherulities in hybrid PVDF membranes were more uniform and smaller than those in neat PVDF membrane quenched at 0°C because of heterogeneous nucleation of TiO2 particles. And spherulities in hybrid PVDF membranes were larger than those in neat PVDF membrane quenched at the same temperature when the quenching temperature was higher than 60°C. TiO2 particles were easy to be separated from PVDF at high quenching temperature. The added TiO2 and the increase of quenching temperature restrained the growth of (020) plane of PVDF. The crystal type (α) was not affected by the change of quenching temperatures and the addition of TiO2. The non-isothermal crystallization process was studied by Ozawa and Jeziorny approach. The results showed the crystallization rate of PVDF increased with the increase of cooling rate. The addition of TiO2 could accelerate the crystallization rate. [Copyright &y& Elsevier]

Abstract: One of the potential applications of ultrafiltration in oleochemical and biodiesel industries is the separation of palm oil and oleic acid from a glycerin–water solution. In this work, the effect of the palm oil concentration (0.001–0.1g/L), oleic acid concentration (0.003–0.1g/L), blend of palm oil and oleic acid concentrations, and pH (2–9) of blended palm oil and oleic acid on membrane fouling were studied using a single-stage Hermia’s model. A multistage Hermia’s model was used to identify the transition time of the fouling mechanism during the ultrafiltration experiment. The single-stage Hermia’s model showed that cake formation was most likely to happen as the highest correlation of determination (R 2) was achieved, followed by intermediate blocking, standard blocking and complete blocking regardless of the foulant types, concentration and pH. The multistage Hermia’s model was proven to be capable of identifying the fouling mechanism that dominated at a certain experimental time and also of predicting the transition time of each fouling mechanism that occurred during ultrafiltration. Lastly, the finding in the multistage Hermia’s model analysis was verified through scanning electron microscopy and further supported by Fourier transform infrared spectroscopy and contact angle measurement. [Copyright &y& Elsevier]

Abstract: The development of polyvinylidene fluoride (PVDF) membrane-based dot immunoassay for rapid and simultaneous detection of multi-mycotoxins in cereal samples is described. To facilitate the simultaneous identification of multiple mycotoxins in a single test, membrane reaction zones were constructed using PVDF membrane, rubber fences and scotch tape. The cut-off level for this method, assessed visually, were 20, 60, 1000, 20, and 250μgkg−1 for Aflatoxin B1, zearalenone, deoxynivalenol, ochratoxin A, and fumonisins B1, respectively, and the final results can be obtained within 10min. This simultaneous method was designed to be simple, with no time-consuming cleanup procedure, and good accuracy and reproducibility were obtained in recovery experiments. These results suggest that this method could be a useful on-site screening tool for the rapid detection of multiple mycotoxins in cereal samples without special instrumentation. [Copyright &y& Elsevier]

Abstract: Polyvinylidene fluoride (PVDF) flat sheet membranes with inter-connected pores were prepared via a non-solvent assisted thermally induced phase separation (Nat-ips) process. Triethylphosphate (TEP) was used as the latent solvent to prepare the metastable PVDF casting solution. The asymmetric ultra- and symmetric micro‐filtration membranes were respectively prepared by adjusting the polymer concentration and quench bath composition. Finger-like pores were totally eliminated and highly inter-connected pores were formed in both membranes. The morphology, crystallization, and mechanical strength of PVDF membranes were characterized by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), X-ray Diffraction (XRD), and tensile strength testing respectively. The effective through-pore size and pore size distribution of PVDF membranes were investigated by a bubble-point method. Pure water flux, protein rejection and fouling resistance were measured to study the filtration performance. All results showed that PVDF membranes with highly inter-connected pores and unimodal pore size distribution could be readily prepared by the Nat-ips process. The ultra- and micro‐filtration PVDF membrane exhibited a pure water flux of 120 and 1860L/m2 h with the corresponding effective through-pore size of 0.11μm and 0.26μm respectively. [Copyright &y& Elsevier]

Abstract: A facile, effective method was first used to graft zwitterionic monomer sulfobetaine methacrylate (SBMA) onto the surface of PVDF membrane via physisorbed free radical grafting technique. The mechanism of free radical initiating grafting polymerization on PVDF membrane was investigated preliminarily. The key factors affecting the graft density (GD), include monomer concentration, reaction time and the temperature, were investigated in the present study. As the result, the graft density of PSBMA on PVDF membrane was improved with the increasing of monomer concentration and reaction time. Around 70°C was the optimum temperature for the grafting. Attenuated total reflectance/Fourier transform infrared spectroscopy (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS) were conducted to confirm the chemical composition of the membrane surface. The morphology of membranes was characterized by scanning electron microscopy (SEM). After the PSBMA was grafted, the hydrophilicity of membrane surface was improved. The water contact angle decreased from 59° to 17° within 120s was achieved at the surface of membrane with GD 0.608mg/cm2. The static protein adsorption and the dynamic fouling-resistance experiment demonstrated that grafting PSBMA on the surface endow PVDF membrane excellent anti-fouling ability. [Copyright &y& Elsevier]

Abstract: An attempt to improve hydrophilicity and anti-fouling properties of PVDF membranes, a novel amphiphilic zwitterionic copolymer poly(vinylidene fluoride)-graft-poly(sulfobetaine methacrylate) (PVDF-g-PSBMA) was firstly synthesized by atom transfer radical polymerization (ATRP) and used as amphiphilic copolymer additive in the preparation of PVDF membranes. The PVDF-g-PSBMA/PVDF blend membranes were prepared by immersion precipitation process. Fourier transform infrared attenuated reflection spectroscopy (FTIR–ATR) and X-ray photoelectronic spectroscopy (XPS) measurements confirmed that PSBMA brushes from amphiphilic additives were preferentially segregated to membrane–coagulant interface during membrane formation. The morphology of membranes was characterized by scanning electron microscopy (SEM). Water contact angle measurements showed that the surface hydrophilicity of PVDF membranes was improved significantly with the increasing of amphiphilic copolymer PVDF-g-PSBMA in cast solution. Protein static adsorption experiment and dynamic fouling resistance experiment revealed that the surface enrichment of PSBMA brush endowed PVDF blend membrane great improvement of surface anti-fouling ability. [Copyright &y& Elsevier]

Abstract: Palm oil and oleic acid are found in many solutions from a variety of production processes such as transesterification and hydrolysis. Feasibility study on ultrafiltration of glycerin solution containing palm oil and oleic acid is limited. In this work, the effects of different palm oil concentrations, different oleic acid concentrations, blend of different palm oil and oleic acid concentrations, and pH on membrane flux decline and rejection ability were examined. The present studies showed that only palm oil was contained in the glycerin solution where the palm oil molecule tended to condense on the membrane surface. The oleic acid molecule in oleic acid–glycerin solution tended to foul into the membrane inter-pore. The blend of palm oil and oleic acid in glycerin solution performed better in flux decline than the solution containing either palm oil or oleic acid alone. However, the pH adjustment of original solution would cause the degradation of membrane performance in terms of final permeate flux and flux decline percentage. This study demonstrated that ultrafiltration was capable of removing palm oil, oleic acid and blend of palm oil and oleic acid from glycerin solution, up to 87.00%, 98.59% and 95.60%, respectively. [Copyright &y& Elsevier]

Abstract: This paper describes a facile and novel approach for the surface glycosylation of poly(vinylidene difluoride) (PVDF) microporous membrane. A glycopolymer poly(d-gluconamidoethyl methacrylate) (PGAMA) was tethered onto the membrane surface via activators generated by electron transfer atom transfer radical polymerization (AGET ATRP) directly initiated from the PVDF surface. Chemical changes of membrane surface were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). It was revealed that PGAMA was successfully grafted onto the membrane surface and its grafting density can be modulated in a wide range up to 2.4μmol/cm2. The effects of glycosylation on membrane morphology, flux and surface hydrophilicity were investigated. Field emission scanning electron microscopy (FESEM) results indicated shrinkage of the surface pore diameters and the growth of the glycopolymer layer on the membrane surface. The static water contact angle (WCA) of the membrane surface decreased from 110° to 30.4° with the increase of grafting density, indicating that the PGAMA grafts dramatically improved the surface hydrophilicity. The protein adsorption and platelets adhesion experiments indicated that the grafted PGAMA could effectively improve the membrane antifouling property and biocompatibility. [Copyright &y& Elsevier]

Abstract: Recently, inorganic nanoparticles blended within polymeric membranes have shown improved antifouling performance in wastewater treatment. However, agglomeration of nanoparticles remains as one of the major obstacles for generating a uniform surface. In this study, a new method for in situ preparation of Al-containing PVDF ultrafiltration membranes to improve the dispersion of nanoparticles is reported. The strategy of this method is to combine sol–gel process with traditional immersion precipitation process. Al sol was synthesized by the addition of anionic exchange resin in N,N-dimethylformamide (DMF) solvent containing aluminum chloride. Homogeneous Al-containing PVDF casting solution was then obtained by dissolving PVDF polymer in the Al sol. The membrane formation mechanism was investigated by precipitation kinetics and morphology. Results indicate that the addition of Al species can accelerate phase inversion of casting solution. Scanning electron microscopic images show that a typical transition from sponge-like structure to finger-like structure occurred with increasing Al species content. The existence and dispersion states of Al species in the resultant membrane matrix were further examined by transmission electron microscope and X-ray photoelectron spectrometer. The results indicate the Al species nanoparticles were well dispersed throughout PVDF matrix. Dynamic BSA fouling resistance experiments demonstrate the Al-containing PVDF membranes possess improved separation performances over the pure PVDF membranes. [Copyright &y& Elsevier]

Abstract: Submerged ultrafiltration process was studied for treatment of refinery wastewater using PVDF hollow fiber membranes. The membranes were prepared via the phase inversion method by dispersing LiCl·H2O and TiO2 in the dope to study the effects of surface properties on membrane performance. The comparison of the performance and morphology was conducted on prepared PVDF composite membranes with various LiCl·H2O and TiO2 contents. The hollow fiber membranes were characterized by field emission scanning electron microscope (FESEM) and energy dispersive x-ray (EDX), average pore size and effective porosity measurements, contact angle measurement, permeability and rejection test. Maximum results were observed for membrane hydrophilicity, membrane porosity and average pore size when the TiO2 concentration was 1.95%. It was also found that interactions between the membrane surface and suspended solid constituents strongly influenced the membrane fouling. The maximum flux and rejection of refinery wastewater were 82.5L/m2 h and 98.8%, respectively, when the PVDF composite membrane with TiO2 content of 1.95% is used at pH=6.9. [Copyright &y& Elsevier]

Abstract: Polyvinylidene fluoride (PVDF) membranes modified by the nano-sized TiO2/Al2O3 were applied to the separation of oil/water emulsion. Experiments were carried out in a constant flux dead-end Ultrafiltration cell, and the influence of operating parameters such as: trans-membrane pressure (TMP), and feed properties e.g. pH, initial oil concentration, and total dissolved solid (TDS) of the feed solution on membrane performance were investigated. The results show that all the parameters except TDS played an important role in Relative Flux (RF) of this UF process, Moreover, Modified PVDF membrane (MPM) showed a better antifouling character than PVDF membrane (PM) under the same conditions. A satisfying flux recovery was observed for fouled membranes when being washed with pure water, and even better when washing with NaClO solution. However, reversed cleaning by water and mechanical scrubbing led to the RF decreased sharply. It was concluded that MPM may be considered feasible in treating oily wastewater. Due to the enhanced hydrophilicity, all the modified PVDF membranes exhibited higher RF and better antifouling property compared with the control PVDF membrane under the same operational conditions. [Copyright &y& Elsevier]

Abstract: We have demonstrated label-free THz sensing of living body-related molecular binding using a thin metallic mesh and a polyvinylidene difluoride (PVDF) membrane. Metallic meshes in the THz region are designed for anomalous transmission phenomena derived from a resonant excitation of surface waves. Additionally, they are designed to have a sharp dip in transmittance. The metallic mesh is very sensitive to a change of the refractive index of materials attached to the metallic mesh. In this paper, we report sensing of interactions between lectin and sugar using this technique. We found that the dip frequency shift, transmittance attenuation of the dip frequency, and peak shift of the derivative spectrum of the phase shift depend on the bonding amount of lectin–sugar interactions. We also applied this technique to detect avidin–biotin interactions, leading to the detection of a small amount of biotin (0.17pg/mm2). [Copyright &y& Elsevier]

Symmetric network poly(vinylidene fluoride) (PVDF) membranes without a dense skin layer were prepared by vapor-induced phase separation from a PVDF/N,N-dimethylacetamide (DMAc)/water system. The effects of evaporation atmosphere, temperature, and humidity during the preparation of the membranes on their morphologies were investigated by scanning electron microscope (SEM). With low temperature and high humidity, the polymer crystallization mechanism dominated the membrane formation process, and the casting solution formed membranes with symmetric morphologies in the vapor phase containing 0.79% DMAc. The effect of additives on the membrane structure and performance was also investigated. The results of adsorption experiments showed that the binding capacity of bovine serum albumin (BSA) increased with the appearance of a circular network morphology and the decrease of mean pore size of the membrane. With the addition of LiCl to the casting solution, the obtained membrane can adsorb BSA up to 150 μg/cm2. Proteins on sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis gels were successfully electro-blotted onto these PVDF membranes. Compared with commercial membranes, the PVDF membranes prepared in this work were more suitable for protein blotting. [ABSTRACT FROM AUTHOR]

Abstract: A microporous polyvinylidene fluoride (PVDF) membrane was prepared from a PVDF/N-methyl-2-pyrrolidone (NMP) solution using liquid-induced phase separation with 2-propanol as the soft coagulant. In this paper, the effect of the dissolving temperature on the morphology and crystalline structure of PVDF membrane and subsequently on protein binding was studied. Field emission scanning electron microscopy (FESEM) was performed to observe the membrane morphology, and Differential Scanning Calorimeter (DSC) along with Fourier transform infrared (FTIR) spectroscopy was used to investigate the crystallinity and crystalline structure of the membrane respectively. The FESEM and FTIR results show that membrane morphologies and crystalline changed significantly as a result of the dissolving temperature, while no obvious change observed on the crystallinity of the membrane, based on the DSC results. It was found that a critical temperature of 40°C existed. At lower temperatures, the protein binding ability was governed by the crystalline structure of the membrane, whereas at temperatures greater than 40°C, the protein binding was primarily governed by the membrane porosity. [Copyright &y& Elsevier]

Abstract: This article provides a comprehensive overview of recent progress on the production and modification of poly(vinylidene fluoride) (PVDF) membranes for liquid–liquid or liquid–solid separation. The crystalline properties, thermal stability and chemical resistance were firstly considered in this review, followed by the production methods of PVDF membranes via phase inversion including immersion precipitation and thermally induced phase separation. Various hydrophilic modification approaches such as surface modification and blending modification for improving the fouling resistance of PVDF membranes were subsequently reviewed. Finally, in the light of the anticipated role of PVDF as a superior membrane material, future prospects on the production and modification of PVDF membranes were suggested. [Copyright &y& Elsevier]

Abstract: The aim of this study was to investigate the effect of pore-forming hydrophilic additives on the porous asymmetric polyvinylideneflouride (PVDF) ultrafiltration (UF) membrane morphology and transport properties for refinery produced wastewater treatment. PVDF ultrafiltration membranes were prepared via a phase inversion method by dispersing lithium chloride monohydrate (LiCl·H2O) and titanium dioxide (TiO2) nanoparticles in the spinning dope. The morphological and performance tests were conducted on PVDF ultrafiltration membranes prepared from a different additive content. The top surface and cross-sectional area of the membranes were observed using a field emission scanning electron microscope (FESEM) and energy dispersive X-ray (EDX) analysis. The surface wettability of porous membranes was determined by the measurement of a contact angle. The mean pore size and surface porosity were calculated based on the permeate flux. The results indicated that the PVDF/LiCl/TiO2 membranes with lower TiO2 nanoparticles loading possessed smaller mean pore size, more apertures inside the membrane with enhanced membrane hydrophilicity. LiCl·H2O has been employed particularly to reduce the thermodynamic miscibility of dope which resulted in increasing the rate of liquid–liquid demixing process. The maximum flux and rejection of refinery wastewater using PVDF ultrafiltration membrane achieved were 82.50L/m2 h and 98.83% respectively at 1.95 wt.% TiO2 concentration. [Copyright &y& Elsevier]

Abstract: This contribution demonstrates a method for PVDF microporous membrane modification via surface-initiated activators generated by electron transfer atom transfer radical polymerization (AGET ATRP) directly from the membrane surface. Three hydrophilic polymers, poly(2-(N,N-dimethylamino) ethyl methacrylate) (PDMAEMA), poly(2-oligo (ethylene glycol) monomethyl ether methacrylate) (POEGMA), and poly(2-hydroxyethyl methacrylate) (PHEMA), were grafted from the PVDF membrane surface in aqueous solution at room temperature. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) confirmed the successful covalent tethering of the polymer chains onto the PVDF membrane surface. The gravimetry results indicated an approximately linear increase of the graft yields, up to about 330μg/cm2 for DMAEMA and 470μg/cm2 for both HEMA and OEGMA, with the polymerization time. Block copolymer brushes were prepared by chain extension. Water contact angle decreased over 50% for high yields, indicating improved surface hydrophilicity. The effects of the graft polymerization on membrane surface morphology, pore structure and permeability were investigated. It was found that the surface roughness was decreased and the pore size distribution was narrowed. The membrane permeability increased at low graft yields due to the enhanced hydrophilicity and decreased at high graft yields due to the overall reduction of the pore diameters. [Copyright &y& Elsevier]

Abstract: An innovative matrix composed of a poly(vinylidene fluoride) (PVDF) membrane modified by adding alumina (Al2O3) nanoparticles was prepared. Pd/Fe nanoparticles (NPs) were successfully immobilized in the PVDF·Al2O3 membrane, which was initially crosslinked by polyacrylic acid (PAA). The PVDF·Al2O3 membrane and the Pd/Fe NPs immobilized in PVDF·Al2O3 were characterized by scanning electronic microscope (SEM), energy dispersive spectrometry (EDS) and Fourier transform infrared spectroscopy (FT-IR). Studies showed that the amount of Fe immobilized in the PVDF·Al2O3 membrane was four times more than the amount in a traditional PVDF membrane carrier of the same surface size. Pd/Fe NPs immobilized in PVDF·Al2O3 exhibited high efficiency and stability in terms of dechlorination of monochloroacetic acid (MCAA). The effects of several important experimental parameters, including the added Al2O3 amount in PVDF, ferrous concentration in crosslinking solution and Pd content in Pd/Fe NPs were investigated. The reasons behind the improved properties of the PVDF·Al2O3 membrane were discussed. [Copyright &y& Elsevier]

Abstract: Poly(vinylidene fluoride) (PVDF) based ultrafiltration membranes were prepared from a PVDF/nano γ-Al2O3 complex suspension where the γ-Al2O3 is well dispersed. The effect of nano γ-Al2O3 concentration on the membrane performances was investigated. Surface chemical compositions, surface and cross-section morphologies and hydrophilicity of the membranes were characterized by Fourier transform infrared spectroscopy (FTIR), Differential Scanning Calorimeter (DSC), Scanning Electron Microscopy (SEM) and contact angle measurement, respectively. The mechanical strength of the membranes was also investigated. Permeation experiments were conducted to evaluate the water flux. Both static and dynamic BSA fouling resistance performances were investigated. All the experimental results indicate that the new PVDF ultrafiltration membranes demonstrate better separation performances over the pure PVDF membranes. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this study is to investigate the potential process for the removal of carbon dioxide (CO2) from flue gas using fundamental membrane contactor, which is a membrane gas absorption (MGA) system. The experiments consisted of microporous polyvinylidenefluoride (PVDF) flat sheet membrane with 0.1μm (as module I) and 0.45μm (as module II) pore size. 2-Amino-2-methyl-1-propanol (AMP) solution was employed as the liquid absorbent. The effect of AMP concentration was studied with variation in the range 1–5M. In addition, the experiments were carried out with 10%, 20%, 30% and 40% gas ratio of CO2 to N2 and pure CO2 as well. Through contact angle measurement, membranes for module I and module II were obtained with CA values of around 130.25° and 127.77°, respectively. The mass transfer coefficients for module II are lower than those of module I for 1–5M of AMP. Furthermore, the increase in CO2 concentration in the feed gas stream enhanced the CO2 flux as the driving force of the system was increased in sequence from 1M to 5M of AMP. However, after the particular percentage (40%) of CO2 inlet concentration, the CO2 fluxes seem saturated. The combination of AMP as liquid absorbent and PVDF microporous membrane in MGA system has shown the potential to remove the CO2 from flue gas. In addition, the higher AMP concentration gave higher mass transfer coefficient at low liquid flow rates. [Copyright &y& Elsevier]

Abstract: This work aimed to study the decolorization of dye wastewater by ozonation membrane contacting process. Three different dyes, i.e., Direct red 23, Acid blue 113 and Reactive red 120 were selected to be used in this work. The effects of operating parameters which were gas and liquid velocity, liquid phase temperature, dye auxiliary reagents were investigated along with the mass transfer study. Membranes used in this work were PVDF and PTFE hollow fiber membranes. The ozone mass transfer performance and long term performance in ozonation by these two different types of membrane were studied. In addition, decolorization performance and kinetic study of ozonation in the batch system with various operating parameters and dye types were investigated. From the results, the ozone mass transfer increased with increasing liquid velocity, liquid phase temperature, and with the presence of Na2CO3. On the contrary, the ozone flux was not influenced by gas velocity. PVDF membrane provided higher ozone flux than PTFE, but PTFE membrane gave more stable and higher flux than PVDF for a long operation period. The ozone flux of different types of dye was in the following order: Direct red 23>Reactive red 120>Acid blue 113. Conversely, the decolorization performance of Acid blue 113 was higher than those of Direct red 23 and Reactive red 120. Kinetic analysis showed that decolorization of dyes followed the first order kinetics and the rate constants were in the following order: Acid blue 113>Reactive red 120>Direct red 23. [Copyright &y& Elsevier]

To improve the filtration efficacy of polyvinylidene fluoride (PVDF) membranes in milk processing, a series of chemical modifications are proposed in this study. First the membranes were treated in KOM/KMnO4 and then H2SO4/NaHSO3 solutions to introduce active groups on to the membrane surface to turn them into hydrophilicity. Next glycerin solution was used to improve the chemical durability of the modified membrane surface. By measuring the flux through the membranes during filtration, significant performance improvement was confirmed. The treatment parameters, including the reagent concentrations, temperature and reaction time etc, were adjusted as well to seek the optimal reaction conditions. [ABSTRACT FROM AUTHOR]

Abstract: This work studied modification of hydrophobic membrane by chitosan solution for the purpose of reducing protein fouling. The membrane used was flatsheet polyvinylidenefluoride (PVDF) of 0.22μm pore size. The membranes were modified by 3 different methods, i.e. immersion method, flow through method and the combined flow through and surface flow method. Chitosan solution concentration and modification time were varied. The modified membranes were then neutralized with NaOH solution. The results of scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) study of modified membranes compared to unmodified membranes confirmed that there was chitosan coated on the membrane surfaces. The water contact angles and water fluxes decreased with increasing chitosan concentration and modification time. The result also indicated that modified membranes had higher hydrophilicity than unmodified membrane. In protein fouling experiment, bovine serum albumin (BSA) was used as a protein model solution. Modified membranes exhibited good anti-fouling properties in reducing the irreversible membrane fouling. The membrane modified by a combined flow through and surface flow method showed the best anti-fouling properties compared with other methods. Protein adsorption on the modified membrane was highest at the isoelectric point (IEP) of BSA solution and decreased as the solution pH was far from the IEP. [Copyright &y& Elsevier]

Abstract: We describe a simple and robust assay for the quantitative detection of prions using immuno-quantitative real-time PCR (iQ-RT-PCR) made possible by a direct conjugate of a prion-specific antibody (ICSM35) and a synthetic 99-bp DNA tail. The DNA tail was engineered to include a single ScrFI restriction site, which enabled subsequent quantification of restricted DNA tails using real-time PCR. The assay was tested with scrapie prions bound to polyvinylidene difluoride membranes and to 96-well plates coated with a capturing antibody from a commercially available immuno-based assay (TeSeE). The iQ-RT-PCR assay had a detection limit corresponding to 2.32×102 prion epitopes, which represented a 1000-fold increase in detection sensitivity over the commercial assay. Detection of prions from diluted scrapie-positive brain homogenate bound to membranes was linear over a range of 1.06×104 to 3.24×102 epitopes (R 2 =0.92). Given its sensitivity and versatility, the present assay has potential to enable rapid and reliable detection of agents causing transmissible spongiform encephalopathies. [Copyright &y& Elsevier]