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Defined as an assembly of polymer chains which are tethered by one end to a surface or an interface, polymer brushes have found many applications. In particular, grafting of hydrophilic polymer brushes to the membrane surface was used to mitigate fouling of filtration membranes. As well, hydrophobic polymer brushes were grafted on top of a solid substrate to be used for organic selective pervaporation. In this work, grafting of hydrophobic brushes to the surface of membranes for membrane distillation (MD) is proposed to prevent MD membranes from wetting. This is not an experimental work but a computer simulation of designing the polymer brush or patterned polymer brush to optimize their effect on wetting prevention. It was found that such an effect increases with an increase in the distance between brushes, the contact angle and the radius of the cylindrical polymer brush. Considering the decrease in the effective area of the membrane used for vapor permeation by grafting of polymer brush, the optimal distance between the brushes was found to be twice as large as the brush diameter for millimeter-sized brush and three times as large as the brush diameter of micro- or nanometer sized brushes. [ABSTRACT FROM AUTHOR]

Metal--organic frameworks (MOFs) are widely explored for advances in hybrid membranes because of their bonding and favourable attraction in polymers. In particular, hybrid polymeric ultrafiltration (UF) membranes are fabricated using engineered MOFs as fillers with the aim of long-standing water treatment. The hydrophilic MOF-199 was synthesized by a facile method at room temperature and incorporated with a polyvinylidene fluoride (PVDF) casting solution to create novel hybrid PVDF/MOF-199 UF membranes via a phase inversion method. The hybrid UF membranes showed higher pure water permeation of 187 L m-2 h-1, which is 2.8 times greater than that of a pristine PVDF membrane, and the water contact angle is decreased to 53.51. The porosity also increased due to an enhancement in hydrophilicity and also retains the rejection property for contaminants such as BSA and HA at their limits, indicating a good trade-off between permeability and rejection. The permeability results are in good agreement with the surface morphology and roughness of the membranes, as shown in the SEM and AFM images, respectively. Contact angle images and TGA studies established the hydrophilicity and thermal stability of the hybrid membranes. BSA and HA permeation studies revealed antiorganic fouling while a zone test clearly demonstrated antibiofouling by the hybrid UF membranes. Overall, the PVDF/MOF-199 hybrid membranes are found to have potential for use in industrial and domestic water treatment. [ABSTRACT FROM AUTHOR]

Graphene has intriguing electrical, mechanical, thermal and biological properties that are being investigated for use in composites, modern electronics, membranes, and in the industry. Also, graphene has huge biological applications. Hydroxypropyl methylcellulose (HPMC) is a widely used bio-polymer effective for various biomedical applications. As a filler in this polymer matrix, graphene oxide (GO), reduced graphene oxide (RGO) and silver (Ag) nanoparticles (NPs) can be used to improve various properties of the matrix. They are also beneficial for bio-applications like drug delivery, the production of reactive oxygen species (ROS) and the antimicrobial properties of nanocomposite films. Here we synthesize a series of polymer nanocomposites taking GO, RGO and Ag NPs as a filler by the solution mixing method and explore the comparative biological application of such composites. We choose Ag NPs as it has the superior potential for multiple drug resistance. X-ray diffraction, Fourier-transform infrared and scanning electron microscope studies are used to describe how nanocomposites are formed. Energy-dispersive X-ray and dynamic mechanical analyzer analyses were also done to check elemental percentage in nanocomposite films and mechanical properties, respectively. To check several fruitful applications, antimicrobial properties, ROS generation and in-vitro drug release study of nanocomposite films with the loading of Ketorolac Tromethamine were also performed. [ABSTRACT FROM AUTHOR]

Sulfonated poly(ether sulfone) (SPES) based proton exchange membranes (PEMs) are fabricated using sulfonated molybdenum disulfide (S-MoS 2) nanosheets via facile solution casting method. SPES (DS = 30%) and S-MoS 2 are synthesized and sulfonation is evidently observed in FTIR and XRD analysis. The anchoring of sulfonic acid group on exfoliated molybdenum disulfide (E-MoS 2) and elemental composition of S-MoS 2 are confirmed by XPS spectrum. Physico-chemical characteristics such as ion-exchange capacity (IEC), water uptake, swelling ratio and oxidation stability are found to be increases after the addition of S-MoS 2 into SPES matrix. Increment in S-MoS 2 content in SPES matrix decreases the surface contact angle due to the increase in hydrophilicity. Further, the dispersing ability of S-MoS 2 in SPES matrix is evidently shown by an increase in surface roughness, tensile strength and thermal stability of the SPES/S-MoS 2 nanocomposite membranes. On the whole, SPES/S-MoS 2 -1 membrane showed the highest proton conductivity of 5.98 × 10−3 Scm−1, selectivity of 19.6 × 104 Scm−3s, peak power density of 28.28 mWcm−2 and lesser methanol permeability of 3.05 × 10−8 cm2s−1. The strong interfacial interaction between SPES and S-MoS 2 in nanocomposite membranes create strong hydrogen bond network to facilitate the proton conduction pathway via both vehicle and Grotthuss type mechanisms. Overall results suggested that the SPES/S-MoS 2 nanocomposite membranes are superior and appropriate alternative for commercially high-cost Nafion® membranes for use in renewable direct methanol fuel cell (DMFC) devices. Image 1 • Superior and low-cost SPES PEMs were fabricated using S-MoS 2 as nano-additive. • SPES/S-MoS 2 -1 PEM showed better proton conductivity of 5.98 × 10−3 Scm−1 and membrane selectivity of 19.6 × 104 Scm−3s. • SPES/S-MoS 2 -1 PEM exhibited a higher power density of 28.28 mWcm−2 and lesser methanol permeability of 3.05 × 10−8 cm2s−1. • SPES/S-MoS 2 PEMs found to be an alternate for expensive Nafion in DMFCs. [ABSTRACT FROM AUTHOR]

• Flat sheet polyvinylidene fluoride - polytetrafluoroethylene (PVDF - PTFE) nanocomposite membranes were fabricated. • The flux of the nanocomposite membrane was 464% higher than that of the neat PVDF membrane. • Water contact angle increased from 67.8° to 87.4° by incorporating of PTFE. • Salt rejection ratio remained unchanged when the feed temperature was increased. Supported flat sheet polyvinylidene fluoride - polytetrafluoroethylene (PVDF-PTFE) nanocomposite membranes were fabricated for this study using the phase inversion process. Several characterization methods, such as scanning electron microscopy, atomic force microscopy, attenuated total reflectance - Fourier transform infrared spectroscopy, water contact angle, and liquid entry pressure of water (LEP w) measurements, were carried out on the prepared membranes, and vacuum membrane distillation (VMD) experiments were then applied to test membrane permeabilities. The cooperation of PTFE was demonstrated to have great potential in enhancing the permeate flux of PVDF membranes while maintaining an acceptable LEP w value. At a feed temperature of 30 °C and vacuum pressure 97.54 kPa, the VMD pure water permeates flux of the prepared nanocomposite membrane embedded with 40 wt% PTFE was 5.61 kg/m2·h, while that of pure PVDF membrane was 0.71 kg/m2 h. The salt rejection results of the prepared nanocomposite membranes were all above 99.9%. These results indicate the applicability of the PVDF-PTFE nanocomposite membranes supported on non-woven polyester fiber for desalination. [ABSTRACT FROM AUTHOR]

The purification process of wastewater containing heavy metal ions (HMIs) using nano-fibrous metal-organic frameworks, MOF-808, embedded polyacrylonitrile membrane has been studied. The process parameters that were evaluated included feed concentration, transmembrane pressure (TMP), and membrane thickness. The effect of coexisting cations in the solution upon the removal efficiencies of Zn2+, Cd2+, Pb2+ and Hg2+ ions was also investigated. Results from the filtration experiments indicate a substantial variation in the feed volume that the membrane can treat before the permeate lead concentration reaches the allowable limit of 10 ppb, depending on the process parameter. An increase in the membrane thickness showed a significant improvement (26%) with 440 L of the treated feed volume after doubling the membrane layer. An increase in TMP could reduce the treated feed volume by 38% while a decrease in feed concentration led to a 21% increase in the treated feed volume. In the presence of other common background cations in the solution, the removal efficiency of HMIs by adsorption onto MOF-808 dropped by 18 to 37%. This result was dependent upon the HMIs, in the presence of up to three other cations but was minimal in the presence of a single cation indicative of good selectivity. Unlabelled Image • Metal-organic frameworks particles were enmeshed into polyacrylonitrile nanofiber membranes. • The membranes were used for the removal of Pb2+ ions from aqueous solution by adsorption. • The effects of transmembrane pressure, feed conc., and membrane thickness were investigated. • The presence of background ions on adsorption Zn2+, Cd2+, Pb2+ and Hg2+ ions was studied. • The filtration system could produce >500 L of pure water per m2 of membrane. [ABSTRACT FROM AUTHOR]

Contamination of water with pollutants that are toxic and/or carcinogenic has led to serious and irreversible consequences to the quality and safety of the water that we consume on a daily basis. This has led to extensive research worldwide to find immediate and effective solutions to this problem. One such practically efficient solution is the treatment of contaminated water for the removal of added contaminants. Among the materials used for water treatment, adsorbents and photocatalysts have been used extensively since they are easy to fabricate, functionalize and use, and they demonstrate high removal efficiencies. Very recently, polythiophene and its derivatives, as well as modified composites of polythiophene and its derivatives, have emerged as extremely promising adsorbent and photocatalyst materials. These materials possess high charge density, surface area and a number of sites to interact and adsorb pollutants. Herein, the research progress achieved so far regarding the fabrication and application of these polythiophene-based adsorbents/photocatalysts toward water purification has been summarized. [ABSTRACT FROM AUTHOR]

Sulfonated poly (ether sulfone) (SPES) membranes are fabricated using polydopamine layered molybdenum disulfide (PDM) nanosheets. The exfoliated molybdenum disulfide (E-MoS 2) nanosheets are subjected to surface coating with self-polymerization of dopamine and probed by FT-IR and EDAX analysis. Membranes are characterized by FT-IR, XRD, SEM, AFM, contact angle, water uptake, ion-exchange capacity, proton conductivity, methanol permeability, TGA, mechanical and oxidative stability. Characterization results confirmed that the SPES/PDM nanocomposite membranes are better than bare SPES and Nafion-212 membranes possibly due to the interface electrostatic attraction between amine groups (-NH 2 and –NH-) of PDM with sulfonate (SO 3 −) group of SPES which create the strong acid-base pair. This result in the enhancement of the proton transport pathway in nanocomposite membranes and also the PDM reduces the methanol transport channels by generating the tortuous path. SPES/PDM-1 membrane exhibits the highest proton conductivity of 5.64 × 10-3 Scm-1, methanol resistivity of 2.23 × 10-8 cm2s-1 and selectivity of 22 × 104 Scm-3s. SPES/PDM membranes are displayed better thermal, mechanical and oxidative stability probably due to the uniform distribution of PDM on SPES matrix as evidenced by SEM images. Overall results confirmed that the SPES/PDM membranes will be an alternate to expensive Nafion in clean energy DMFC devices. Image 1083 • SPES/Polydopamine coated E-MoS 2 nanocomposite PEMs are fabricated effectively. • Polydopamine coated E-MoS 2 are well dispersed in to the SPES matrix. • SPES/PDM-1 PEM shows higher proton conductivity and methanol resistance. • SPES/PDM PEMs are superior to bare SPES and Nafion-212 membranes. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Membranes with multi-walled carbon nanotubes (MWCNTs) and two additives MWCNTs/SiO 2 were fabricated. • With the MWCNTs addition, the average pore size decreases, but the finger-like pores are extended. • Hybrid nanocomposite membranes with 1% SiO 2 , integrated additive shows synergetic effects on vapor flux through membrane. • High SiO 2 content could increase liquid entry pressure of water of membrane compared with membrane blended MWCNTs only. • MWCNTs exhibits different effects on tensile properties of membrane when loading ratio of SiO 2 is different. Abstract Polyvinylidene fluoride (PVDF) was blended with multi-walled carbon nanotubes (MWCNTs) and MWCNTs/SiO 2 nano-additives to fabricate nanocomposite vacuum membrane distillation (VMD) membranes for desalination. The effects of MWCNTs and MWCNTs/SiO 2 integrated additives on the morphology and performance of the PVDF membrane were studied. When only MWCNTs were used, 2 wt% loading of MWCNTs to PVDF had the maximum effect on the improvement of VMD flux, due primarily to the enlargement and elongation of the finger-like pores. Then, one of three different SiO 2 nanoparticles (NPs) (hydrophobic, superhydrophobic and hydrophilic) was further added to the membrane that already contained 2 wt% of MWCNTs. When the amount of SiO 2 NPs was relatively low, VMD flux increased as a result of the synergistic effects between the two filler components, i.e. one is the increase of overall porosity by MWCNTs and the other is the growth of the macrovoids by SiO 2 NPs. But among those two, the effect of MWCNTs was more dominant. Compared with the pristine PVDF membrane and the nanocomposite PVDF membrane with a single filler of MWCNTs, respectively, the flux increase by the addition of SiO 2 was 292% and 55%. On the other hand, when a relatively large amount of SiO 2 NPs was added, the effect of SiO 2 NPs started to dominate. Especially, the asymmetric structure of the membrane disappeared, leading to low mechanical strength. All fabricated membranes exhibited great desalination potential with salt rejection as high as >99.97%. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Chitosan/Exfoliated molybdenum disulfide composite membranes were fabricated for use in direct methanol fuel cells. • Chitosan-0.75% membrane showed higher proton conductivity (2.92 × 10−3 Scm−1) and membrane selectivity (8.9 × 104 Scm−3 s). • Chitosan-0.75% membrane exhibited lower methanol permeability of 3.28 × 10−8 cm2 s−1. • Tailored chitosan nanocomposite membranes found to be a proficient alternative to costly Nafion. Abstract Chitosan based proton exchange membranes (PEMs) has been synthesized by a facile solution casting strategy using two-dimensional exfoliated molybdenum disulfide (E-MoS 2) nanosheets. The prepared PEMs are characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Field-emission scanning electron microscopy (FESEM) with Energy dispersive X-ray spectroscopy (EDX), water uptake, Thermogravimetric analysis (TGA), AC impedance spectroscopy and cyclic voltammetry. In comparison with pure chitosan membrane, E-MoS 2 nanosheets incorporated membranes exhibit excellent water absorbing capacity, ion-exchange capacity and proton conductivity. Moreover, the changes in roughness of nanocomposite membranes is investigated by atomic force microscopy (AFM) and the results confirm that the E-MoS 2 nanosheets content enhances the surface roughness as well as provide good mechanical and thermal resistivity to the chitosan/E-MoS 2 membranes. Chitosan membranes with 0.75% E-MoS 2 nanosheets demonstrated higher proton conductivity of 2.92 × 10−3 Scm−1 and membrane selectivity of 8.9 × 104 Scm−3 s with reduced methanol permeability of 3.28 × 10−8 cm2 s−1. Overall, results evidenced that the chitosan/E-MoS 2 nanocomposite membranes will be an alternate to Nafion in direct methanol fuel cells (DMFCs). [ABSTRACT FROM AUTHOR]

Herein, we report the effect of modification of cellulose acetate (CA) ultrafiltration (UF) membranes via bioinspired polydopamine (PD) coating followed by in situ immobilization of silver nanoparticles (AgNPs). Such a modification resulted in excellent hydrophilicity, contaminant rejection and minimized both organic fouling and bio-fouling properties. PD coating imparts high surface hydrophilicity and anti-organic fouling properties, whereas the immobilized AgNPs provide excellent anti-biofouling properties to the modified membrane. The immobilization of AgNPs on the CA membrane surface is achieved by simple immersion of the membrane into a silver nitrate solution. The catechol groups present in the membrane facilitate the immobilization of AgNPs via a metal coordination. Leaching tests were also conducted to determine the concentration of the AgNPs in the permeate using Atomic Absorption Spectroscopy (AAS) and we inferred that the concentrations are lower than the usual contaminant limit. Also the contact angle (55.8°), pure water flux (113.1 L m−2 h−1) and biofouling experimental results of the modified membranes confirm that there is a significant enhancement in the membrane hydrophilicity, permeability, anti-fouling and anti-biofouling properties when compared to the pristine CA membrane. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A simple mathematical model was presented for membrane adsorption by nanofibrous membrane. • A model based on the combined Carmen-Kozeny equation and Darcy’s law. • A model based on mass balance reproduction of the breakthrough curve of heavy metal ions. • Model parameters were correlated to membrane properties and operating conditions. Abstract The environmental consequences of lead ion accumulation have been linked to detrimental health impacts in humans. Hence, removal of heavy metal (lead, Pb) ions by membrane adsorption/filtration was studied in this work using nanofibrous membranes in which the adsorbent metal-organic framework, MOF-808, was embedded. S-shaped breakthrough curves were obtained experimentally when the heavy metal concentration in the permeate was plotted vs the filtration period. Simple model equations that enable the reproduction of the S-shaped breakthrough curve were derived. It was found that the model equations could simulate the experimental data reasonably well. Attempts were further made to correlate the parameters involved in the model equations to the properties of mixed matrix nanofibrous membranes, including the pore size and pore size distribution, membrane thickness, fiber diameter, the adsorption rate constant, the Langmuir adsorption constant and the maximum adsorption capacity. The model equation parameters were also correlated to the operating conditions including the heavy metal concentration in the feed and the transmembrane pressure difference. It is believed that the model equations, despite this simplicity, can provide deeper insight into the membrane adsorption/filtration phenomena. These equations also contribute to the process design for successful removal of heavy metal ions from the environment to improve health factors for humans. [ABSTRACT FROM AUTHOR]

Manganese dioxide (MnO2) nanospheres were prepared by a facile hydrothermal technique and their influence on the permeation and antifouling properties of poly(vinylidene fluoride) (PVDF) ultrafiltration (UF) membranes was investigated. Different concentrations of MnO2 nanospheres (such as 0.0, 0.5, 1.0 and 2.0 wt%) were added and they were designated as pristine PVDF, PVDF-0.5, PVDF-1 and PVDF-2, respectively. AFM images confirmed that upon increasing the wt% of MnO2 nanospheres, there is an increase in the surface roughness of the PVDF/MnO2 nanocomposite membranes. Further, SEM images revealed the formation of finger-like macrovoids along with improved porosity. Moreover, upon increasing the wt% of MnO2 on PVDF, the pure water flux was enhanced and attains a value of 153.4 Lm−2 h−1 for the PVDF-2 nanocomposite membrane. Fouling experiments were performed using bovine serum albumin (BSA) and humic acid (HA) as model fouling contaminants. Experimental results confirmed that the higher flux recovery ratio (FRR) of the PVDF/MnO2 membranes indicates the enhancement of their hydrophilicity and antifouling ability. Tensile strength results suggested that the PVDF/MnO2 membranes possess improved mechanical resistance compared with the pristine PVDF due to the change in their morphologies. However, increasing the concentration of MnO2 beyond 2% resulted in phase inversion during membrane fabrication and hindered the membrane formation. The results confirmed that the PVDF-2 membrane outperformed other membranes employed in this work in terms of improved permeation and antifouling properties, without compromising the BSA or HA rejection and membrane strength. In light of all these results, it is evident that the MnO2 nanosphere incorporated PVDF nanocomposite UF membrane shows potential for water treatment applications. [ABSTRACT FROM AUTHOR]

Supported flat sheet nanocomposite polyvinylidenefluoride (PVDF) membranes embedded with hydrophilic TiO 2 , hydrophobic TiO 2 , or the combination of them were fabricated via phase inversion process. The membranes were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, atomic force spectroscopy, and the measurement of water contact angle and liquid entry pressure of water and subjected to tests on vacuum membrane distillation (VMD) performance. Addition of appropriate amounts of either hydrophilic or hydrophobic NPs was found to enhance VMD flux but hydrophilic NPs caused significant decrease of liquid entrance pressure of water (LEPw ) while hydrophobic particles did not show significant impacts on LEP w. Addition of both hydrophilic and hydrophobic NPs demonstrated synergistic effects in terms of both enhanced flux and LEP w due to their different but complimentary effects on membrane structures. At feed temperature of 27.5 °C, the VMD pure water permeate flux of the composite membrane embedded with 5 wt% hydrophilic TiO 2 NPs and 2 wt% of hydrophobic TiO 2 NPs (total 7 wt% NPs) was 4.26 kg/m 2 h with a LEP w of 28 psi, while those of neat PVDF membrane, the membrane embedded with 7 wt% of hydrophilic NP, and the membrane with 7 wt% hydrophobic nanoparticles were 0.335, 3.57, and 1.25 kg/m 2 h, respectively, and the LEPw of these membranes were 51, 24 and 47 psi, respectively. It is noted that at 5 wt% addition, the flux of M-L5 (hydrophilic NPs) is 3 times higher than the M-B5 (hydrophobic NPs). Furthermore, by adding another 2 wt% of NPs, flux increment by M-L5-B2 (hydrophobic NPs) is 3.5 times higher than M-L7 (hydrophilic NPs). Therefore, in both the effects combined, the highest flux was achieved by M-L5-B2 indicating synergistic effect of hydrophilic and hydrophobic NPs on the membrane flux. The salt rejection of above 99% could be maintained for 3 h by the membrane in which both hydrophilic and hydrophobic NPs were loaded. Numerical analyses of heat and mass transfer were also carried out to study the impact of hydrophilic and hydrophobic NPs on membrane characteristics. [ABSTRACT FROM AUTHOR]

Herein, we report the effect of the exfoliated molybdenum disulfide (eMoS 2 ) nanosheets in improving the permeability and anti-fouling properties of the PEI ultra-filtration (UF) membrane using bovine serum albumin (BSA) and humic acid (HA) as model fouling agents. The PEI/eMoS 2 nanocomposite membranes were prepared via phase inversion method using three different eMoS 2 concentrations (0.5, 1 and 2 wt%) designated as PEI-0.5, PEI-1 and PEI-2, respectively. Fourier transform infra-red spectroscopy employed to probe the surface functionalities on the membranes. Contact angle measurement, pure water flux, swelling rate and solute rejection studies confirmed the improved hydrophilicity of the PEI/eMoS 2 nanocomposite membranes than the individual entities. Flux recovery ratio (FRR), reversible and irreversible fouling results evidenced the improved fouling resistance of PEI/eMoS 2 modified membranes than the individual counterparts. SEM results evidenced that the nanoscale eMoS 2 significantly altered the membrane morphology by causing increased porosity and larger macrovoids formation on the surface as well as in the bulk of the membrane. PEI-1 membrane showed an increased pure water flux (52.54 L m − 2 h − 1 ) and water content (74.8%) whereas lesser contact angle (69.2 ° ) and hydraulic resistance (1.85 kPa/L m − 2 h − 1 ). Resistance to fouling performance of PEI-1 membrane was evident from the FRR values of 95.3 and 90.2% and rejection values of 94.5 and 92.4% for BSA and HA respectively. PEI-2 membrane agglomerates with eMoS 2 and hindered the membrane permeability by blocking the macrovoids in the bulk which restricted the permeation and fouling resistance of the membrane. Amongst various nanocomposite membranes investigated, the PEI-1 membrane exhibited better hydrophilicity and fouling resistance properties due to the availability of the favorable surface and bulk characteristics. [ABSTRACT FROM AUTHOR]

Exfoliated molybdenum disulfide (E-MoS2) nanosheets were synthesized from bulk MoS2. Poly(vinylidene fluoride) (PVDF) was incorporated into E-MoS2 to yield nanocomposite ultrafiltration (UF) membranes by the phase inversion technique. Various proportions of E-MoS2 (0.1, 0.5 and 0.8 wt%) were prepared and were characterized in terms of permeation and antifouling properties. FT-IR and XRD studies confirmed the presence of E-MoS2 in the membranes. Moreover, SEM and FESEM/EDX analysis of the membranes confirmed the increase in the porosity and presence, respectively, of E-MoS2. Atomic force microscopy (AFM) images confirmed that the membrane with 0.5 wt% E-MoS2 exhibited a uniform surface structure with (Ra = 35 nm), compared to the pure PVDF membrane (Ra = 37.6 nm). In addition, the membrane with 0.5 wt% E-MoS2, exhibited higher pure water flux (PWF) (105.1 L m−1 h−1), water content (73.7%), porosity (12.24%), bovine serum albumin (BSA) solute rejection (92.3%), least mechanical stability (1.13 MPa), hydraulic resistance (7.44 kPa L−1 m−2 h−1) and contact angle (72.8°). From all these, it is evident that the overall PVDF membrane performance was enhanced by the E-MoS2 addition, and the membrane with 0.5 wt% E-MoS2 outperformed the other counterparts due to its versatile characteristics and superior potential in the water treatment. [ABSTRACT FROM AUTHOR]

The innovative concept of a zero-waste, energy efficient, and therefore sustainable desalination strategy, Zero Thermal Input Membrane Distillation (ZTIMD), is demonstrated to be economically more effective than existing seawater desalination technologies by simulation based on a single-pass Direct Contact Membrane Distillation process using surface seawater as the feed and bottom seawater as the coolant. Thermal energy required for water distillation in the process was satisfied by extracting the enthalpy of the surface seawater using the bottom seawater as the heat sink. Under one of the favorable conditions, the proposed ZTIMD process could produce pure water with a cost of $0.28/m 3 at a specific energy consumption of 0.45 kW h/m 3 , which is significantly lower than that of the major existing seawater desalination processes, including the currently dominating technology, Reverse Osmosis ($0.45–2.00/m 3 ). Some major advantages promised by the ZTIMD include (1) With no requirement of external thermal energy input, ZTIMD is an inherently energy-saving process, (2) it is economically competitive to existing desalination technologies, and (3) it is waste-free. [ABSTRACT FROM AUTHOR]

[Display omitted] • Unique strategy to produce tunable FRET emission as a function of medium pH. • Maximum sensing efficiency of the biosensor at a particular pH. • Drastic FRET ON-and-OFF behavior in aqueous media. • Conformational change of the drug molecules at elevated pH resulting stable fluorescent exciplex switching off the FRET emission. • Proficient cell permeability of the sensor will help in the controlled drug delivery to tumor cell lines. The present contribution depicts a unique approach to generate tunable Förster resonance energy transfer (FRET) emission with variation of pH of the medium. The pH sensitive absorption of Doxorubicin leads to modification of spectral overlap between emission spectra of donor (Pyrazoline) and absorption spectra of acceptor (Doxorubicin) thereby sensing maximum FRET efficiency in an optimum pH (near pK a of Doxorubicin). This drug molecule exhibits an instantaneous conformation change at a particular pH, which consequences on abrupt ON-and-OFF FRET efficiency. At elevated pH, both the drug molecules exhibit conformational change and form stable fluorescent exciplex, switching off the FRET emission. Confocal fluorescence images of live HepG2 cells imply that the sensor can proficiently go through the cell membrane and can be applied in the controlled delivery of drug to the tumor cell lines. [ABSTRACT FROM AUTHOR]

The re-entrant structure of the membrane surface has attracted researchers' attention recently, due to its ability to make the membrane surface more wetting resistant-either in water or in liquids of low surface tension. The underlying principle of this approach is that an energy barrier has to be overcome when the transition occurs from the Cassie Baxter state to the Wenzel state of the rough membrane surface, which prevents the passage of liquid through the membrane pore. In this work, the energy barrier was evaluated for the cone-shaped pore based on Young's theory of the capillary force. It was found that the energy barrier is enhanced by increasing the angle of the apex of the cone, the pore length, and the contact angle. The effects of the first two geometrical factors, the angle of apex of cone and pore length, are much stronger than the effect of the contact angle. It is believed that this work will offer a guideline for the rational membrane design to reduce, and even prevent, the pore wetting of membranes, particularly for oil/water separation and membrane distillation. [Display omitted] • The energy barrier arising in movement of water/air interface in a cone-shaped pore was evaluated based on Young's theory. • The effects of the apex angle of the cone, pore length, and contact angle on the energy barrier were investigated. • The guideline of the re-entrant structured pore was given to prevent the transition from Cassie-Baxter to Wenzel state. [ABSTRACT FROM AUTHOR]

The aim of this research was the analysis of heat and mass transfer in vacuum membrane distillation (VMD), specifically for a dead-end feed set-up. The influence of support material on the supported membranes VMD performance was identified. A mathematical model was proposed to evaluate the membrane/feed interface temperature, membrane tortuosity, membrane mass transfer coefficient, and temperature polarization coefficient (TPC). The model was solved by an excel solver based on experimental results of feed temperature, system pressure and the evaporative fluxes. The SEM images showed that the thickness of unsupported membrane was reduced by 42% after the VMD test. Pore shrinkage and tortuosity increase were also expected during this pore collapsing process. On the other hand, the cross-sectional views of the supported membranes did not show significant changes. These results show that the support material can help prevent the membrane pore channel structure from collapsing during the VMD experiment. TPC is close to unity at low feed temperatures. However, it decreases with an increase in evaporation flux as the feed temperature increases, or when a high flux supported membrane is applied. [ABSTRACT FROM AUTHOR]

Separation using selective polymeric membranes has been well-established as an energy-efficient and cost-effective technology in water treatment and many other applications involving aqueous solutions. However, limited chemical, thermal, and mechanical resistances besides their tendency to fouling and inadequate pure water flux may often restrict their applications. To this end, inorganic materials as additives have been demonstrated to be able to enhance chemical, thermal, and fouling membrane resistances, which demonstrate their great potential for developing novel membranes by using them as additives in polymer matrices. Considering the excellent characteristics of the nanosized particles, this study reviews the effects of inorganic nano-additives on properties and performance of polymer/nanoparticle composite membranes. It has been demonstrated that using nanomaterials in a polymer matrix could enhance the mechanical strength and stiffness, wettability, selectivity, water permeability, and antifouling characteristics of the host polymer. [ABSTRACT FROM PUBLISHER]

Membrane distillation (MD) is a promising separation technique capable of being used in the desalination of marine and brackish water. Poly(vinylidene fluoride) (PVDF) flat sheet nano-composite membranes were surface modified by coating with electro-spun PVDF nano-fibres to increase the surface hydrophobicity. For this purpose, the nano-composite membrane containing 7 wt.% superhydrophobic SiO 2 nano-particles, which showed the highest flux in our previous work, was first subjected to pore size augmentation by increasing the concentration of the pore forming agent (Di-ionized water). Then, the prepared flat sheet membranes were subjected to nanofibres coating by electro-spinning. The uncoated and coated composite fabricated membranes were characterized using contact angle, liquid entry pressure of water, and scanning electron microscopy. The membranes were further tested for 6 h desalination by direct contact membrane distillation (DCMD) and vacuum membrane distillation (VMD), with a 3.5 wt.% synthetic NaCl aq as the feed. In DCMD the feed liquid and permeate side temperature were maintained at 27.5 °C and 15 °C, respectively. For VMD, the feed liquid temperature was 27 °C and a vacuum of 94.8 kPa was applied on the permeate side. The maximum permeate flux achieved was 3.2 kg/m 2 .h for VMD and 6.5 kg/m 2 .h for DCMD. The salt rejection obtained was higher than 99.98%. The coated membranes showed a more stable flux than the uncoated membranes indicating that the double layered membranes have great potential in solving the pore wetting problem in MD. [ABSTRACT FROM AUTHOR]

Effects of hydrophilic silica nanoparticles and Non-Woven Fabric (NWF) backing material on the properties and performance of the Polyvinylidene Fluoride (PVDF) membrane have been studied in this work. The nanocomposite membranes were prepared by the phase inversion method and characterized in terms of surface pore size, cross-sectional morphology, thickness, porosity, surface roughness and hydrophobicity. The fabricated membranes were subjected to Vacuum Membrane Distillation (VMD) experiments and their performance was evaluated through measuring the pure water flux and salt rejection. According to the results, effects of the hydrophilic nano-additives and NWF polyester enabled much higher VMD flux than the neat PVDF membrane when an appropriate amount of the nano-filler was added, possibly due to increase in the surface pore size and the reduction of the sponge-like layer thickness. The supported nanocomposite membranes possessed appropriate Liquid Entry Pressure (LEP w ) and mechanical strength, which make the membrane applicable in VMD process. When 7.0 wt.% of the silica nanoparticles was incorporated in a NWF supported membrane, the pure water flux became 12749.6 g/m 2 h at feed temperature of 27.5 °C and permeate side pressure of 1.2 kPa, representing a 2456% increase from the neat PVDF membrane. Almost complete NaCl rejection was also achieved when tested with 35 g/L NaCl aqueous solution. [ABSTRACT FROM AUTHOR]

Membranes were prepared from three poly(vinylidene fluoride) (PVDF) of different molecular weights by the phase inversion process. The membranes were characterized by scanning electron microscopy, gas permeation tests, contact angle (CA) and liquid entry pressure of water (LEPw) measurements, and further subjected to the test of flux for vacuum membrane distillation (VMD) in a scenario that is applicable for cooling processes. The results showed that the increase in PVDF molecular weight increased the viscosity and thermodynamic instability of the casting solution significantly. Regarding characterization and performance testing, the membrane prepared from the intermediate molecular weight of Kynar® MG 15 polymer showed the highest VMD flux (325 g/m 2 h) at the feed temperature of 27 °C and the lowest LEPw (622 kPa) due to the largest pore size (49.8 nm) observed among all the tested membranes. The highest flux of this particular membrane seems also due to the thinnest finger-like and sponge-like layer. [ABSTRACT FROM AUTHOR]

A facile one-pot approach for rapid synthesis of silver and gold nanoparticles (Ag NPs and Au NPs) with narrow size distribution and good stability was described by reducing silver nitrate and chloroauric acid with polysaccharide dextrin. Here, dextrin was used as both a reducing and stabilizing agent for synthesis of NPs. The as-synthesized Ag NPs and Au NPs were characterized by UV–visible absorption spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD). The Ag NPs and Au NPs exhibited an absorption maxima at 404 and 547 nm respectively. TEM images showed NPs in the range of 8–28 nm. The crystallinity of the NPs was measured by XRD analysis. Furthermore, the as-prepared Ag NPs revealed colorimetric sensor property for detection of Cu 2+ ions based on changes in absorbance resulting from metal ion-induced aggregation of NPs or direct deposition of metal ions onto NPs. The as-prepared Au NPs exhibited a notable catalytic activity toward the reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH 4 . [ABSTRACT FROM AUTHOR]

In this study, composite membranes of hydrophilic CuO and CaCO 3 nanoparticles and polyvinylidene fluoride (PVDF) were developed by phase inversion method. The fabricated membranes were subjected to different characterizations including morphology study, pore size, porosity, and thickness measurement, wettability and surface roughness analysis. The membrane performance was examined in terms of pure water flux in vacuum membrane distillation (VMD), salt rejection, and liquid entry pressure of water (LEP w ). It was found that the membrane performance was optimized when 1.0 to 2.0 wt.% of CuO nanoparticles were embedded into the PVDF matrix via enhancing the membrane structure through enlarging surface pores and thickening the finger-like layer (in other words, thinning of the sponge-like layer). As a result, flux increased by 153.4% at the feed temperature of 27.5 °C and vacuum pressure of 1.2 kPa, when 2.0 wt.% of the CuO nanoparticles were embedded in PVDF. Membrane selectivity did not drop as a result of the CuO nanoparticles incorporation and was more than 99.99%. All the nanocomposite membranes showed reasonable contact angle and LEP w, which proved appropriateness of the fabricated membranes for VMD application. Regarding the type of hydrophilic nanomaterials, CuO demonstrated better performance than CaCO 3 in terms of membrane permeability improvement. [ABSTRACT FROM AUTHOR]

Novel aliphatic polyurethane (PU) nanohybrids have been prepared using varying amount of graphene by dispersing it in the early stage of polymerization ( in situ ) and achieved uniform distribution throughout the matrix, required for the improvement of properties. The alteration of self-assembly in presence of graphene have been explored through X-ray diffraction, small angle neutron scattering, atomic force and optical microscopy in the length scale of nanometer, tens of nanometer, hundreds of nanometer and micron range, respectively, indicating the layer by layer self-assembly of polymer and graphene in nanohybrids. The cause of self-assembly has been studied through spectroscopic techniques like FTIR and UV–vis measurements revealing strong interaction between polymer chain (both hard and soft segments) and graphene which is further confirmed from the depression of melting point and decrease in heat of fusion with increasing graphene content in the nanohybrids. The toughness of nanohybrids in solid state improves considerably as compared to pure PU and the mechanical strength in liquid state also dramatically increases with graphene content showing a dip at a particular frequency depending on the strength of self-assembly (greater for higher graphene content nanohybrid) followed by its reformation at higher frequency. Sustained drug release has been achieved in presence of graphene explaining the phenomena from the greater tortuousity in nanohybrids arising from the 2-D graphene and small but uniform cluster size of self-assembly as compared to pure PU. The suitability of the developed nanohybrids has been testified for its use in biomedical arena by checking the complete biocompatibility of the nanohybrids as compared to pure PU using bone marrow derived mesenchymal stem cells. [ABSTRACT FROM AUTHOR]

In this study membranes were fabricated from the blend of high (H) and low (L) molecular weights poly(vinylidene fluoride) by the phase inversion process. The membranes so fabricated were characterized by scanning electron microscopy, gas permeation tests, contact angle (CA) and liquid entry pressure of water (LEPw) measurement, and further subjected to vacuum membrane distillation (VMD) in a scenario that was applicable for cooling processes, where the feed water temperature was maintained at 27 °C. It was found that the H:L mixing ratio did not affect the membrane surface hydrophobicity (as reflected by the CA) significantly. The water vapor flux of VMD was found to be the highest at the intermediate range of H:L ratio, i.e., 4:6, at which the thickness of the sponge-like layer showed a minimum, the pore size showed a maximum, the finger-like macro-voids formed a more orderly single-layer structure, and the LEPw showed a minimum. [ABSTRACT FROM AUTHOR]

Highlights: [•] Modulation of photophysics in proteolytic globular enzyme and serum albumins. [•] Binding affinity of ANAP with albumins is much greater than trypsin. [•] Efficiency tunable FRET from excited Trp to ANAP. [•] Docking simulations of drug within biomolecules. [•] Hydrophobicity driven association of ANAP ensues for distinctive micropolarities in proteinous assembly. [ABSTRACT FROM AUTHOR]

Highlights: [•] Modulation of photophysics in different micellar assembly. [•] Rotational behavior in confined media. [•] Dramatic enhancement of the PCM fluorescence in the CTAB micelles upon addition of quencher. [•] Ion exchange phenomenon operative at the micelle surface. [•] Development of highly polarity sensitive fluorescence molecular probe. [Copyright &y& Elsevier]

Highlights: [•] Novel NF cellulose acetate membrane developed using charged tailor-made additive. [•] Novel NF membrane and commercial NF membrane field tested for PPCP removals. [•] New membrane achieved significant removals of ibuprofen and sulfamethazine. [•] Commercial NF membrane had somewhat better PPCP removals and higher fluxes. [Copyright &y& Elsevier]

Abstract: Nanofiber membranes were fabricated by electrospinning poly(vinylidene fluoride). The electrospun nanofiber membranes were further modified by grafting of acrylic acid (AA) and methacrylic acid (MAA) over the surfaces of the membranes. Plasma AA graft was attempted only, and the results indicated the partial membrane pore filling with grafted AA. For MAA grafting, chemically induced polymerization using benzoyl peroxide and hydrogen peroxide was attempted. The combination of plasma and chemically induced MAA graft polymerization was also attempted. The membranes were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and static contact angle (SCA) measurement. SEM surface analysis indicated partial pore narrowing of grafted membranes. The average pore size was reduced from 0.97μm for the untreated membrane to 0.15μm for the two step plasma and chemically induced grafted membranes. XPS analysis confirmed that grafting has taken place on the top surface of the membranes. The surfaces of the grafted membrane were significantly hydrophilic as observed by SCA. It was also found that the combination of plasma and chemically induced grafting using hydrogen peroxide was the most effective in terms of flux and selectivity. The grafting reduced the pore size by filling the pores of the original membranes by the graft polymers. This practice resulted in producing tight micro-filtration (MF) membranes from loose MF ones. An impressive high water flux of 150kg/hm2 at an operating pressure of 4 psig, and a 79% removal of polyethylene oxide (molecular weight 400kilo-Daltons) were achieved. [Copyright &y& Elsevier]

Abstract: Fluorescence recognition and sensing of aqueous anionic species is a challenging task and is being increasingly appreciated as far as potential biological and environmental issues of such systems are concerned. In the present contribution, we introduce for the first time fluorescence amplified recognition of a naphthalimide derivative (NAP) being embedded in a cationic alkyl trimethyl ammonium bromide micellar (C n TAB) units by various anions applying steady state and time resolved fluorescence techniques. Strongly quenched NAP emission in micellar framework has been effectively recovered upon intervention of various anions (such as H2PO4 −, HPO4 2−, PO4 3−, SO4 2−, Cl−, etc.) with different sensitivities. The sensing process based on ion displacement mechanism, which principally governs a proficient fluorescence enhancement to various anions in a simple and efficient way, has been demonstrated. Optimization of sensor is achieved by altering surfactant chain length. The intermolecular approach used here seems to be rather flexible and appealing to design interface oriented fluorescent sensors to convene different analytic purposes for a wide variety of anion targets. [Copyright &y& Elsevier]

Abstract: Pharmaceutical and personal care products (PPCPs) enter the environment mainly through municipal wastewater effluents, agricultural run-off, pharmaceutical and related chemical industry discharges. The present study was conducted to remove PPCPs through nano-filtration (NF) membranes prepared with two different tailor-made polymeric additives. The first is a novel charged surface modifying macromolecule (CSMM) additive synthesized by reactive diisocyanate and dihydroxy naphthalene disulfonate. The second additive was a tailor made hydrophilic SMM (LSMM), which was manufactured incorporating poly(ethylene glycol) as end groups. Cellulose acetate (CA) membranes with and without 3wt% CSMM or LSMM were prepared by the phase inversion technique. The membranes were characterized by static contact angle, X-ray photoelectron spectroscopy, scanning electron microscopy with energy dispersive spectrometer, and atomic force microscopy. The NF filtration studies were conducted at two different operating pressures (150 and 400psig). They consisted of pure water flux tests, sodium chloride separation tests, and individual PPCP (ppm level carbamazepine, ibuprofen, and sulfamethazine) separation tests. The long term NF performance for the removal of ibuprofen was also conducted. Significant effect of CSMM blending on the separation performance of ibuprofen for long hours operation was observed. [Copyright &y& Elsevier]

Abstract: Entrapping of a fluorogenic material comprising prospective therapeutic activity in microhetrogeneous environments and modulating important photophysical properties is highly desirable as far as potential applications of such systems are concerned. The present work demonstrates the interesting photobehavior of a newly synthesized antioxidative naphthalimide (isoquinolinedione) derivative (ANAP) in micellar solutions of anionic sodium dodecyl sulphate (SDS), cationic cetyl trimethylammonium bromide (CTAB) and nonionic p-tert-octylphenoxy polyoxyethanol (TX-100) surfactants using steady-state, time-resolved fluorescence and fluorescence anisotropy techniques. The remarkable sensitivity of the fluorescence properties of ANAP to the polarity of the media is attributed to the existence of a fluorescent intramolecular charge transfer (ICT) state. ANAP is found to be an excellent fluorescence sensor for following the micellar aggregation process. Fluorometric studies suggest that the probe resides at the micelle–water interface in all these systems. The present effort endeavors the degree of accessibility of the fluorophore toward the metal ion quencher in the presence of micelles of different surface charge characteristics. The enhancements in the steady-state anisotropy and rotational relaxation time in the micellar media compared to that in pure aqueous solution reflect that the fluorophore resides in a motionally restricted environment introduced by the micelles. [Copyright &y& Elsevier]

Abstract: The synthesis and solvatochromic behavior of the compound, 7-oxy(5-selenocyanato-pentyl)-2H-1-benzopyran-2-one (PCM), a pervasive, bioactive coumarin derivative, which is expected to possess antioxidative properties and other important therapeutic activities of significant potency with low systematic toxicity, have been reported employing steady state and time resolved fluorescence techniques. Spectroscopic studies reveal that the solvatochromic behavior of the probe depends not only on the polarity of the medium but also on the hydrogen bonding properties of the solvents. Specific hydrogen bonding interaction of PCM in polar solvents modulated the order of the two close-lying lowest singlet states. The photophysical response of PCM in different solvents has been explained considering solute-solvent interactions. To corroborate these results, we performed the ground-state geometry, lowest energy transition and the UV–vis spectrum of PCM using the density functional theory (DFT) and the time-dependent density functional theory (TD–DFT) at B3LYP/6-31G⁎ level. We found excellent correlation between the predicted and experimental spectral data, providing a useful tool in the design of new fluorogenic probes having potential therapeutic activity. [Copyright &y& Elsevier]

Abstract: Popular polymers such as polysulfone and poly(vinylidene fluoride) (PVDF) when electrospun into a membrane, have a much higher contact angle and hence are more hydrophobic when compared to the virgin polymeric material. In direct liquid penetration it is more beneficial if the membrane is hydrophilic so that the flux is not compromised and has less tendency to foul. Hence, this research is focused on generating a highly hydrophilic electrospun membrane (EM) based on PVDF material by blending this polymer with several different types of surface modifying macromolecules (SMMs) prepared from urethane pre-polymer with poly(ethylene glycol)s (PEGs) of various average molecular weights (400, 600, and 1000Da) and poly(propylene glycol) of average molecular weights 3500 and 425Da. One of the SMMs, with PEG 1000Da, had a significant impact on the hydrophilic nature (0° SCA with water) of the EM as compared to the blend casted membrane. This could possibly be due to the orientation of the SMMs hydrophilic groups adopted during electrospinning on the surface, whereas they are either encapsulated or submerged in other SMMs. The water flux at a given pressure of blended EM was higher than the non-blended electrospun PVDF membrane. This study highlights the potential benefits of this new hydrophilic polymeric material in the membrane field, which can achieve high-flux rates at low pressure. [Copyright &y& Elsevier]

This paper investigates how solution conditions, especially solvent polarity and hydrogen bonding, influence the fluorescence of an anticancer drug, doxorubicin hydrochloride (DOX). When excited at 480 nm, this molecule shows single fluorescence. However, when excited at 346 nm, it shows dual fluorescence. The ground and excited state intramolecular double proton transfer in DOX has been observed and investigated to shed light on their corresponding spectroscopy and dynamics in different protic and aprotic solvents. An increase in pH results in enhancement of emission from the ionic conformer with parallel dwindling of emission of the neutral species. Based on the experimental and theoretical studies on DOX, a ground and excited state intramolecular double proton transfer mechanism is proposed to explain the unusual excitation-dependent dual fluorescence of DOX. [ABSTRACT FROM AUTHOR]

Abstract: The present contribution provides detailed information about the development of antifouling novel thin-film-composite (TFC) membranes for mostly water purification with special emphasis on seawater desalination in particular. The novel membranes were prepared by incorporating in-situ hydrophilic surface modifying macromolecules (iLSMM) into the TFC membranes, rendering the surface of the TFC membranes significantly more hydrophilic. The prepared membranes were then subjected to long term fouling studies using model foulants, including sodium humate (SH), silica particles (SPs), and chloroform (CF) spiked in the feed NaCl solution. The biofouling effect of silver salts was also studied by incorporating some silver salts (silver citrate hydrate, SCH; silver lactate, SL; and silver nitrate, SN) simultaneously with iLSMM into the TFC membranes. Halo test was conducted with Escherichia coli to examine the antibiofouling performance of the silver incorporated TFC membranes. It can be concluded by this work that iLSMM incorporated TFC membranes have performed excellently for the desalination of salty water (3.5wt% NaCl), especially when the solution was spiked with typical foulants such as SH, SPs, and CF. The flux reduction was reduced significantly when iLSMM was incorporated in the TFC membranes by a newly developed technique. The antimicrobial fouling intensity of the studied membrane was in the order of: SN (ring width 0.55mm)>SL (0.27mm)>SCH (0.19mm). [ABSTRACT FROM AUTHOR]

Abstract: Fluorescence resonance energy transfer (FRET) between anionic probe 1-anthracene sulphonate (1-AS) and transport proteins, bovine serum albumin (BSA) and human serum albumin (HSA) solubilized in reverse micelles of sodium 1,4-bis (2-ethylhexyl) sulphosucccinate (AOT) in heptane was studied where the donor and acceptor pair comes in close proximity within the smaller water pools. The mechanism of fluorescence quenching of transport proteins by 1-AS in reverse micelles has been ascribed to the non-radiative energy transfer process. The probable binding site of the probe with proteins has been ascertained from FRET study. Circular dichroism study suggests that the number of folding of the protein increases markedly due to binding of the proteins with 1-AS. [Copyright &y& Elsevier]

Abstract: Disinfection byproducts (DBPs), trihalomethanes and haloacetic acids present in water are well known carcinogens and their removal is an important priority. Highly porous nanofibrous membrane filters produced by electro-spinning were carbonized and used for the removal of DBPs from water. In the present investigation, chloroform and monochloroacetic acid (MCAA) was used as model DBPs compounds. The DBPs concentration in the range of 1–100mg/L was used in well controlled adsorption experiments using the prepared membranes. For chloroform an adsorption capacity of 554mg/g of carbonized nanofibrous membranes (CNMs) was determined based on the filtration of feed solution (100mg/L). The adsorption capacity of MCAA was between 287 and 504mg/g for a feed concentration of 4–18mg/L based on the static adsorption study. The used membranes were regenerated by chemical/physical treatment and removal efficiencies of the regenerated membranes were determined. The DBPs removal from water was also investigated using multiwalled carbon nanotubes (MWCNTs) incorporated in the CNMs and results were compared. Although the initial removal of MCAA was increased with increasing concentration of the MWCNTs, afterwards, the subsequent removals showed no effect of addition of MWCNTs. The possible mechanism was also discussed to better understand the adsorption phenomenon. These results suggest that the CNMs could be used as DBPs removal filter for drinking water purpose. [ABSTRACT FROM AUTHOR]

Abstract: The association of a non-ionic surfactant of polyoxyethylene-p-(1,1,3,3-tetramethylbutyl)phenyl ether (Triton X) series with 2-AS in aqueous solution has been studied by means of steady-state, time-resolved fluorescence and fluorescence anisotropy techniques. The effect of the hydrophobic chain length on the structural dynamism of the fluorophore has been reported. Experimental results demonstrate that the equilibrium of this dynamism is sensitive to the environment. The association constant of the probe molecule with the non-ionic micelles of Triton X (TX), location of the probe in the micellar environment, have been determined from the change in emission characteristics of the probe as a function of surfactant concentration. The rate constant of quenching and mode of quenching of probe in micellar media have been ascertained. Quantitative estimates of the micropolarity at the binding sites of the probe molecule have been determined. Some of the environment-dependent relevant fluorescence parameters, fluorescence anisotropy (r), have been monitored for exploring the imposed motional restriction of the microenvironment around the probe. An attempt has been made to correlate the steady-state results with time resolved study. [Copyright &y& Elsevier]

Abstract: The poly(ether sulfone) (PES) membranes were prepared by blending of two types of surface modifying macromolecules (SMMs)-charged (cSMM) and fluorinated (fSMM). Also, membranes were fabricated in three different conditions: (1) at room temperature (RT) without air-exposure period (the period between film casting and immersion into coagulation bath), (2) at RT with 3min air-exposure period and (3) at 90°C with 3min air-exposure period. The performances and physico-chemical characteristics of the membranes were evaluated. Membrane surface became more hydrophilic when cSMM was blended while more hydrophobic when fSMM was blended. Detailed analysis of the surface free energy demonstrated that the hydrophilic surface was resulted form strong Lewis base (solid)–acid (liquid) interaction while hydrophobic surface was resulted from the weak Lifshitz–van der Waals interaction. Atomic force microscopy (AFM) results could be interpreted by considering the orientation of nodule aggregates at the membrane surface under the casting bar and its relaxation during the air-exposure period between the film casting and immersion to the gelation bath. The pore size of the membranes measured by AFM was much larger than the pore size obtained by filtration experiment. [Copyright &y& Elsevier]

Abstract: The aggregation of surfactant of polyoxyethylene-p-(1,1,3,3-tetramethylbutyl)phenyl ether (Triton X) series in chloroform has been studied. The critical micellar concentration (cmc) of the reverse micelles formed has been determined by four different techniques. The determined cmc values by various techniques are close to each other and facilitate determination of the free energy change (ΔG) values associated with the micellization. From the correlation of cmc with hydrophile–lipophile balance (HLB) it was found that cmc decreases with decrease in HLB values. The association constant of the reverse micelle with fluorescent probe 1-anthracene sulphonate (1-AS) and micellar aggregation number has been evaluated. The location of the fluorophore in the reverse micelle and the polarity of the micelle solubilized sites have been determined from the E T(30), Kosower Z, and dielectric constant values. The pH of the aqueous region of reverse micelles has been estimated by comparison method. [Copyright &y& Elsevier]

Abstract: The separation performances and physico-chemical characteristics of poly(ether sulfone) membranes were evaluated by blending of surface modifying macromolecules (SMMs). Hydrophobic SMMs (bSMM) and charged SMMs (cSMM) were synthesized and characterized. By addition of SMMs, glass transition temperature decreased and membrane pore size increased. The membrane became more hydrophobic by blending of bSMM, and became more hydrophilic after addition of cSMM. It was also demonstrated by the result of surface free energy study that the bSMM blended membrane showed the lowest solid–liquid (water) interaction by low Lifshitz–van der Waals interaction and Lewis acid (liquid)–base (solid) interaction. In contrast, cSMM blended membrane showed the highest Lewis acid–base interaction, which resulted in the highest interaction energy between membrane surface and liquid (water). It was also found from the result of differential scanning calorimeteric measurement that bound water was formed in the cSMM blended membrane. [Copyright &y& Elsevier]

Sulfonated poly (vinylidene fluoride-co-hexafluoropropylene) (SPVDF-co-HFP) based nanocomposite proton exchange membranes (PEM) are fabricated by simple solution casting method using polydopamine coated exfoliated molybdenum disulfide (PDA-MoS 2) nanosheets as an alternative for Nafion® in vanadium redox flow batteries (VRFBs). PDA-MoS 2 is synthesized by the etching of exfoliated MoS 2 nanosheets with dopamine molecule by self-polymerization method. Various characteristic results clearly demonstrated that the incorporated PDA-MoS 2 nanosheets homogeneously distributed into the SPVDF-co-HFP matrix and the presence of NH/NH 2 group electrostatically interacts with SPVDF-co-HFP to form a strong acid-base pair and thus enhances the proton transport via Grotthuss type mechanism. Besides, the improvement in surface hydrophilicity provides the vehicle type conduction also. As a result, SPVDF-co-HFP/PM nanocomposite membranes showed higher proton conductivity in comparison with the pristine membrane. Especially SPVDF-co-HFP/PM-1 membrane demonstrated the excellent proton conductivity of 5.24 × 10−3 Scm−1 at 25 °C, lower vanadium-ion permeability of 1.05 × 10−8 cm2min−1 and highest membrane selectivity of 49.9 × 104 Scm−3min. On the other hand, vanadium-ion stability of the membrane increased by adding the PD-MoS 2 content is attributed to their strong electrostatic attraction towards the polymer matrix. Overall results suggested that the SPVDF-co-HFP/PM-1 nanocomposite membrane is found to be a better alternative for commercially costly Nafion in VRFB applications. Image 1 • Bio-inspired polydopamine coated exfoliated molybenum disulfide (PDA-MoS 2) nanosheets are successfully synthesized. • PDA-MoS 2 nanosheets effectively block the vanadium-ion permeation via SPVDF-co-HFP membranes up to 1.05 × 10−8 cm2min−1. • Acid-base pair formation between SPVDF-co-HFP with PDA-MoS 2 offers a new proton conduction pathway. • SPVDF-co-HFP/PDA-MoS 2 membranes showed higher chemical stability and found appropriate for use in VRFBs. • SPVDF-co-HFP/PDA-MoS 2 membranes are superior to bare SPVDF-co-HFP and Nafion membranes. [ABSTRACT FROM AUTHOR]

• Nanocomposite membranes with various nanoparticles (NPs) were fabricated for a vacuum membrane distillation (VMD) process. • Able to achieve higher VMD flux using a continuous flow cell than that with a static cell. • With increasing temperature, the continuous flow cell yielded higher VMD flux than that of the static cell. • Incorporation of NPs of larger size showed better performance than that of smaller size. • Finger-like voids reached the bottom of the nanocomposite membrane when the cast film thickness was the lowest. In this study, the effects of incorporation of nanoparticles (NPs), including 7 nm TiO 2 , 200 nm TiO 2 , and hydrophilic and hydrophobic SiO 2 with a mean diameter in the range of 15–20 nm, and their concentrations on the membrane properties and vacuum membrane distillation (VMD) performance were evaluated. The effect of membrane thickness and support materials were also investigated. The membranes were characterized extensively in terms of water contact angle, liquid entrance pressure of water (LEP w), scanning electron microscopy, surface roughness, and pore size. While the best polyvinylidene fluoride (PVDF) nanocomposite membranes with 200 nm TiO 2 NPs were obtained at 2 wt% NPs concentration, the optimal NPs concentration was 5% when 7 nm TiO 2 was integrated. Using a nanocomposite membrane containing 2 wt% TiO 2 − 200 nm NPs, a VMD flux of 3.2 kg/m2h and a LEP w of 34 psi were obtained with 99.99% salt rejection. Furthermore, it was observed that decreasing the membrane thickness would increase the portion of the finger-like layer in the membrane and reduce the spongy-like layer when hydrophilic NPs were used. Using continuous flow VMD, a flux of 3.1 kg/m2h was obtained with neat PVDF membranes, which was higher than the flux obtained by the static VMD with the same membrane at the same temperature and vacuum pressure. The fluxes of both static and continuous flow cells VMD increased with temperature. Furthermore, it was evident that the continuous flow cell VMD at 2 L per minute yielded higher flux than the static cell VMD at any given temperature, indicating strong effects of turbulence provided in the continuous flow cell VMD. [ABSTRACT FROM AUTHOR]

Hydrophilic poly(vinylidene fluoride) (PVDF) nanocomposite ultrafiltration (UF) membranes with excellent antifouling and antibiofouling characteristics are fabricated by employing polyhexanide coated copper oxide nanoparticles (P–CuO NPs). The presence of P–CuO NPs is played a significant role in altering the PVDF membrane matrix and probed by XRD, FTIR, FESEM and contact angle analysis. The PVDF/P–CuO nanocomposite membranes exhibited an outstanding antifouling performance indicated by the superior pure water flux, effective foulant separation and maximum flux recovery ratio during UF experiments as a result of the formation of the hydrophilic and more porous membrane due to the uniform distribution of P–CuO NPs. Particularly, the PVDF/P–CuO-3 membrane showed higher PWF of 152.5 ± 2.4 lm−2h−1 and porosity of 64.5% whereas the lower contact angle of 52.5°. Further, it showed the higher rejection of 99.5 and 98.4% and the flux recovery ratio of 99.5 and 98.5% respectively for BSA and HA foulants, demonstrated its increased water permeation, foulant separation and antifouling behavior. Further, the decent antibacterial activity is showed by the PVDF/P–CuO nanocomposite membranes with the formation of halo-zone around the membrane when exposed to the bacterial medium demonstrated that, by this process an antibacterial water treatment membrane can be developed by simple phase inversion technique with good membrane stability. Image 1 • Successful fabrication of PVDF/P–CuO nanocomposite UF membranes. • PVDF/P–CuO membranes showed superior hydrophilicity and water permeation. • PVDF/P–CuO membranes exhibited higher BSA/HA rejection and flux recovery ratio. • PVDF/P–CuO membranes displayed both anti-organic fouling and anti-biofouling. • PVDF/P–CuO membranes are promising for potential use in the water treatment. [ABSTRACT FROM AUTHOR]

Herein, copper oxide nanoparticles (CuO NPs) are synthesized via a facile wet chemical precipitation technique and coated with poly(hexamethylenebiguanide) hydrochloride (PHMB). The surface properties of the resulting PHMB coated CuO (PHMB-c-CuO) are characterized by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) spectroscopy. In order to improve permeation, anti-organic fouling and antibacterial characteristics, PHMB-c-CuO NPs are incorporated into poly(ether imide) (PEI) membrane matrix via a phase inversion technique. The morphological and hydrophilicity investigations confirmed that the influence of PHMB-c-CuO NPs improves the macrovoids, porosity (15.2%) and water permeation (192.8 Lm−2h−1) of the PEI membrane. The rejection and flux recovery ratio (FRR) of the PEI/PHMB-c-CuO membranes are found to be over 97% towards foulants such as bovine serum albumin (BSA), humic acid (HA) and motor oil demonstrated its excellent separation and antifouling ability. Antibacterial activity of PEI/PHMB-c-CuO membrane is studied using Escherichia coli and Staphylococcus aureus. Results showed a wider inhibition zone thereby confirming the excellent antibacterial ability of the PEI/PHMB-c-CuO membrane. Overall, the PEI/PHMB-c-CuO nanocomposite membranes provided outstanding permeation, anti-fouling, and anti-bacterial performance than pristine PEI membrane and promising for effective water treatment applications. Image 10923 • Highly dispersible PHMB-c-CuO nanoparticles into PEI matrix are synthesized. • PEI/PHMB-c-CuO membranes displayed superior hydrophilicity, permeability and antifouling ability. • PEI/PHMB-c-CuO membranes showed better BSA/HA/Oil rejection and antibacterial ability. • PEI/PHMB-c-CuO membranes are promising for potential use in the water treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Evaluated the effect of TFC and TFN membranes for FO desalination. • Discussed the application studies of both TFC-FO & TFN-FO membranes. • TFN-0.25% membrane possessed super hydrophilic behaviors of 12°. • TFN-ZnO-0.5 membrane displayed superior FO flux rate of 84.7 L m-2h−1. • TFN-FO membranes performed superior over TFC-FO membranes. The impact of different additives on the achievement of FO membranes was designed, reviewed, and highlighted the performances of nanocomposite over traditional membranes with evidenced literature support. This review found that the surface hydrophilicity, roughness, porosity, FO water permeation, solute retention, reverse solute permeates (RSP), and specific reverse salt permeate (SRSP) has been greatly affected by the alteration of a skin layered structure of FO membrane. The review revealed that the TFN-FO membranes showed very high surface hydrophilic properties than the TFC-FO membranes. For example, the graphene quantum dots (GODs) based UiO 66 -NH 2 crystals (GQDs@UiO 66 -NH 2 , 250 ppm, TFN-0.25%) membrane had a goniometer (contact angle) reading of 12° which indicated a super-hydrophilic property of nanocomposite membrane over traditional TFC membranes. In addition, the TFN-FO membrane showed the highest FO permeation rate of 84.7 L m-2h−1 for the ZnO-based TFN membrane (TFN-ZnO-0.5) and a very lower RSP value of 0.005 g/L for nylon-6 (N 6) substrate containing silica dioxide (SiO 2) nano particle (NP) support membrane with polyamide (PA) layer nano membrane (E. Spun N 6 /SiO 2 -PA/SiO 2 TFN) suggested an excellent FO performance than TFC membranes. This review also suggested that the TFN membranes provided enhanced salt rejection and FO water flux with superior fouling resistant properties which are important parameters to enhance FO performances. Hence, TFN-FO membranes can utilize as a suitable candidate for desalination applications compared to TFC membranes. [ABSTRACT FROM AUTHOR]