Search

COVID-19 infections and severe acute respiratory syndrome (SARS) have caused an unprecedented health crisis across the globe with numerous deaths, as well as causing a tremendous economic crash worldwide.

Metal–organic frameworks (MOFs) are widely explored for advances in hybrid membranes because of their bonding and fondness in polymers.

Tailored polyacrylonitrile (PAN) ultrafiltration (UF) membranes are fabricated with Pluronic-F127 and polyethylene glycol phosphate decorated calcium carbonate (PGP-CaCO3) additives with the aim of high water permeation, macromolecular rejection and antifouling properties. The nanoscale CaCO3 synthesis is carried out via a single step carbonization route using PGP as a hydrophilic modifier to introduce hydroxyl groups onto its surface. The topographies of the nanoparticles are investigated using X-ray diffraction (XRD) and transmission electron microscopy (TEM). PAN/PGP-CaCO3 mixed matrix membranes (MMMs) are fabricated via phase inversion method and examined by attenuated total reflectance-Fourier infra-red spectroscopy (ATR-FTIR), mechanical stability, thermo-gravimetric analysis (TGA) and scanning electron microscopy (SEM) to explore the changes in membrane properties due to the well-dispersed PGP-CaCO3 in the PAN membrane matrix. The UF performance of the membranes is investigated in terms of pure water flux, macromolecular rejection and antifouling property. The fouling resistance of membranes is assessed using bovine serum albumin (BSA) and humic acid (HA) as model foulants. The membrane loaded with 0.75 wt.% (M3) of PGP-CaCO3 manifested increased wettability with reduced surface free energy leading to a higher pure water flux of 366 L/m2 h. M3 also displayed a rejection of 93.9% for BSA and 93.2% for HA. The success of the modification can be confirmed as the membrane M3 exhibited lower flux decline and displayed a flux recovery ratio of 90.98% during HA filtration. The results demonstrated the potential use of PAN/PGP-CaCO3 membranes in water treatment.

Sulfonated poly(ether sulfone) (SPES) based proton exchange membranes (PEMs) are fabricated using sulfonated molybdenum disulfide (S-MoS2) nanosheets via facile solution casting method. SPES (DS = 30%) and S-MoS2 are synthesized and sulfonation is evidently observed in FTIR and XRD analysis. The anchoring of sulfonic acid group on exfoliated molybdenum disulfide (E-MoS2) and elemental composition of S-MoS2 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-MoS2 into SPES matrix. Increment in S-MoS2 content in SPES matrix decreases the surface contact angle due to the increase in hydrophilicity. Further, the dispersing ability of S-MoS2 in SPES matrix is evidently shown by an increase in surface roughness, tensile strength and thermal stability of the SPES/S-MoS2 nanocomposite membranes. On the whole, SPES/S-MoS2-1 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-MoS2 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-MoS2 nanocomposite membranes are superior and appropriate alternative for commercially high-cost Nafion® membranes for use in renewable direct methanol fuel cell (DMFC) devices.

Herein, the potential impact of tamarind seed polysaccharide (TSP) on the gelation nature and in vitro release of a particular drug, pilocarpine hydrochloride, from different poloxamer 407-based ophthalmic formulations were evaluated. The combination of TSP (0.5–1.5 wt%) and 18 wt% poloxamer (PM) solutions resulted in a significant improvement in gel elasticity under physiological conditions. The introduction of TSP to PM not only enhanced the viscosity of the gel, but also stimulated the gelation procedure. Due to the inclusion of TSP, the gel dissolution rate of the PM-based formulation was greatly reduced. The FTIR spectral analysis revealed the interaction between –OH groups of both polymers, resulting in a decline in the gelation temperature of the PM–TSP-based formulations. It was also detected in the cryo-SEM analysis that the pore size of the PM gel decreased and the depth of its pores increased with the inclusion of TSP. Furthermore, the in vitro release analysis indicated that the retention capacity of PM–TSP-based formulations was superior to that of the only PM-based formulation. The SEM study and the cell viability data demonstrated the biocompatibility and non-toxicity of TSP. Therefore, the designed formulation is fairly promising to be utilized as an in situ ophthalmic drug carrier.

Polymers have a major role in the controlled delivery of pharmaceutical compounds to a targeted portion of the body. In this quest, a high priority research area is the targeted delivery of ophthalmic drugs to the interior regions of the eyes. Due to their complex anatomical/biochemical nature. This necessitates an advanced drug delivery cargo that could administer a therapeutic agent to the targeted location by evading various obstacles. The ongoing focus is to design an ophthalmic formulation by coupling it with a smart in situ forming polymeric hydrogel. These smart macromolecules have an array of unique theranostic properties and can utilize the in vivo biological parameters as a stimulus to change their macromolecular state from liquid to gel. The fast gelling hydrogel improves the corneal contact time, facilitates sustained drug release, resists the burst-out effect, and assists drug permeability to anterior regions. This review summarizes the rationale, scientific objectives, properties, and classification of the biologically important in situ hydrogels in the niche of ophthalmic drug delivery. The current trends and prospectives of the array of stimulus-responsive polymers, copolymers, and nanomaterials are discussed broadly. The crucial biointerfacial attributes with pros and cons are reviewed by investigating the effect of the nature of polymers as well as the ratio/percentage of additives and copolymers that influence the overall performance.

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 (LEPw) 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 LEPw 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.

To improve the interfacial affinity and antifouling properties of polyphenylsulfone (PPSU) membrane, nano CuO/g-C3N4 (g-CN) sheets were synthesized via facile calcination route as one pot synthesis method. The uniformly assembled nanohybrid fillers, CuO on g-CN sheets were confirmed by using XRD, TEM, EDX and FTIR analysis. The non-solvent induced phase inversion technique was used to fabricate the nanohybrid ultrafiltration (UF) membranes by doping different concentration (0.5–1 wt.%) of nano CuO/g-C3N4 (g-CN) sheets within the PPSU matrix. The results of contact angle, atomic force microscopy, energy-dispersive X-ray spectroscopy reveal that surface structure and physico-chemical properties of nanohybrid membrane plays lead role in solute interaction and rejection compared to bare membrane, M0. Furthermore, the interfacial affinity of membrane was explored in detail via surface free energy, spreading coefficient, wetting tension and reversible work of adhesion analysis. Nanohybrid UF membrane, with 0.5% of the filler (M1) displayed remarkable permeation flux of 202, 131 L/m2/hr for pure water and protein solution, respectively while maintaining a high protein rejection (96%). Moreover, the exceptional dispersion of the nanosheets in the polymer matrix enhanced FRR (79%) and decreased the overall resistance of M1 compared to the pristine membrane (M0). Overall results suggest that the incorporation of nano sheets is a facile modification technique which improves the comprehensive membrane performance and holds a great potential to be further explored for water treatment.

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.

Polyvinylidene fluoride (PVDF) was blended with multi-walled carbon nanotubes (MWCNTs) and MWCNTs/SiO2 nano-additives to fabricate nanocomposite vacuum membrane distillation (VMD) membranes for desalination. The effects of MWCNTs and MWCNTs/SiO2 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 SiO2 nanoparticles (NPs) (hydrophobic, superhydrophobic and hydrophilic) was further added to the membrane that already contained 2 wt% of MWCNTs. When the amount of SiO2 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 SiO2 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 SiO2 was 292% and 55%. On the other hand, when a relatively large amount of SiO2 NPs was added, the effect of SiO2 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%.

Sulfonated poly (ether sulfone) (SPES) membranes are fabricated using polydopamine layered molybdenum disulfide (PDM) nanosheets. The exfoliated molybdenum disulfide (E-MoS2) 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 (-NH2 and –NH-) of PDM with sulfonate (SO3−) 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.

MnO2 nanospheres are prepared by simple hydrothermal technique, and their influence on the permeation, antifouling and contaminant removal properties of poly (ether imide) (PEI) ultrafiltration (UF) membranes is investigated by adding them at three different concentrations such as 0.5, 1.0 and 2.0 wt.% (designated as PEI-0.5, PEI-1 and PEI-2). The hydrophilic property of PEI/MnO2 membranes is investigated using contact angle and pure water flux measurements. The addition of MnO2 nanospheres reduces the contact angle to 60.8° and enhances the pure water flux to 129.8 Lm−2h−1 for PEI-1 membrane due to the increased surface hydrophilicity. SEM and AFM characterization revealed that the custom-made membranes showed noticeable changes in the formation of macrovoid, porosity and roughness parameters. During the separation of contaminants such as bovine serum albumin (BSA), humic acid (HA) and oil, the tailored membranes show enhanced rejection (between 96.8 and 99%) and flux recovery ratio (FRR) (between 95.5 and 99.5%) due to the improvement in hydrophilicity and formation of the water layer on the membrane surface proved their better rejection and antifouling capacity. Hydraulic resistance (14.7 kPa/Lm−2h−1) and tensile strength (5.58 MPa) results suggested that, the PEI-1 membrane showed better resistance to pressure and mechanical stress compared to the standard PEI membrane, due to the changes occurred in their morphologies. However, the additive loading limited at 2 wt.%, in order to avoid the negative effects of MnO2 nanospheres at higher concentrations.

This study uses cyclohexanol – a high-carbon, cyclic bio-alcohol which is a derivative of lignocellulosic biomass – in blended form with diesel to power a direct-injection single-cylinder diesel en...

Pentanol and Hexanol are two excellent biofuels that could be derived from lignocellulosic biomass feedstock without disturbing food-based sources. The present study utilizes these two alcohols as ...

In this work simulation results for the pore wetting of vacuum membrane distillation (VMD) are reported, considering heat and mass balance at liquid/vapor interface when steady state is achieved. Two cases were studied. In case 1, the system is in isothermal condition. In case 2, heat enters only from the pore inlet and is removed at the liquid/vapor interface as liquid vaporizes. The simulation has shown that the liquid/vapor boundary may remain inside the pore at the steady state condition, which means the partial pore wetting is possible. The significant temperature drop from the pore entrance to the liquid/vapor interface has also been predicted. It was found from case 2 simulation that VMD is possible in a wider range of pore radius, r, than the Laplace equation predicts. As well, the possibility of VMD for the contact angle (θ) below 90° was justified.

Membrane distillation (MD) is a thermally driven separation process. Despite many advantages over other membrane separation processes, pore wetting hampers the wide commercial applications of the MD process. In this paper, the effect of temperature and presence (or absence) of salt in the feed solution on the wetting properties of commercial polyvinylidene fluoride (PVDF) membrane during a period of eight weeks was investigated. Liquid entry pressure (LEP) and water contact angle (WCA) were employed to characterize the wetting properties of the PVDF membrane. The result shows that the temperature has a significant impact on the decrease of the contact angle of the PVDF membrane.

Research into the structure, synthesis and properties of nanoscale materials has increased at an enormous pace over the past decades since they have a wide variety of applications ranging from adsorption to separation processes in water treatment. A wide range of technologies such as adsorption, electrochemical, membrane filtration, and ion-exchange methods are productively used in water treatment and nanoparticles also find application in each of these fields. Water pollution by various toxic contaminants such as proteins, humic acids, and oils and the shortage of pure water have become the most serious environmental issues encountered worldwide. Recently, nanomaterial-incorporated polymeric ultrafiltration membranes have been used effectively in water treatment technologies to address these environmental issues. Herein, we concisely review the performances of membranes incorporated with a variety of nanomaterials. This review summarizes some very recent results and contributions achieved with nanomaterials to date in the emerging field of ultrafiltration membrane technology research. Further, this review discusses the methods for the incorporation of diverse nanomaterials and their influence in altering membrane properties to improve performance. Special emphasis is given to the hydrophilicity, mechanical and thermal stability, and antifouling and antibacterial activity of nanomaterials.

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.

In this research work, novel perfluorooctanoic acid-modified melamine (PFOM) was synthesized as a hydrophobic filler using a facile one-pot synthesis. PFOM incorporating polyvinylidene fluoride (PVDF) solution was cast on a cellulose sheet to prepare a dual-layered membrane employing the phase-inversion technique for direct contact membrane distillation (DCMD) application. The influence of PFOM to tailor the dual-layered membrane performance was then investigated. The long perfluoro chain in PFOM hydrophobic fillers increased the surface roughness of the membranes due to its random overlapping with PVDF backbone, and these membranes exhibited a higher water contact angle value. The increase in pore size and membrane porosity did not significantly influence the liquid entry pressure of water (LEPw). The microporous membranes displayed good mechanical strength for use in the test setup. Pure water permeation was the highest (6.9 kg m−2 h−1) for membrane (M1) with 1 wt% of PFOM when tested with a simulated sea-water solution (3.5% w/v NaCl) in the direct contact distillation mode. These membranes also achieved the theoretical salt-rejection of 99.9%, thus confirming the potential of these membranes to be investigated for large scale membrane distillation (MD) applications like desalination of seawater.

In this work, novel positively charged NF membranes, decorated with aromatic amine moieties, aminated polyphenylsulfone (PPSU-NH2) were fabricated by the phase inversion technique. The prepared membranes were characterized by scanning electron microscopy, atomic force microscopy, average pore size and molecular weight cut-off. The surface properties of these membranes were determined by ion exchange capacity (IEC), contact angle (CA), surface free energy and water spreading coefficient. The membrane enriched with an aromatic amine (M3) had an overall smoother membrane surface with a pore size of 0.72 nm M3 has a positively charged surface with an IEC of 0.51 meq.g−1 and a highly hydrophilic nature confirmed by a low water CA (∼31°), and the greatest observed pure water flux (∼54 LMH). The amine incorporated membranes showed an increased resistance to fouling when challenged with cetyl trimethyl ammonium bromide as a model foulant, which suggests the existence of repulsive forces shielding the membranes from the positively charged foulants. The M3 showed a considerable rejection of 89 and 93.5% for the multivalent salts CaCl2 and AlCl3, respectively, and expectedly lower rejection of 18.7 and 25.6% for univalent salts Na2SO4 and NaCl, respectively. The prepared membranes demonstrated an exceptional ability in rejection (>99%) of cationic dye crystal violet while maintaining a moderate flux. Therefore, this method of preparation of a positively charged NF membrane can be further investigated for its potential for the removal of dyes and metal ions from commercial waste streams.

BACKGROUND: Ultrafiltration (UF) is a promising separation technique for the removal of macromolecular contaminants. However, the hydrophobic polymeric UF membrane performance suffers from fouling in the long run due to clogging by contaminants at the surface and pores. In this study, anti‐fouling hydrophilic polyacrylonitrile (PAN) UF membranes in the presence of an amphiphilic triblockcopolymer, Pluronic F127 (PF127) were prepared via a phase inversion technique. RESULTS: The effect of varying concentrations of PF127 on PAN UF membranes was analyzed by attenuated total reflectance–Fourier transform infrared spectroscopy (ATR‐FTIR), by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The filtration characteristics of the membranes were measured in terms of pure water flux, membrane porosity and water content. The separation efficiency of the membranes is explored for contaminants such as bovine serum albumin (BSA), humic acid (HA) and oil. The results revealed that the PAN membrane with 4 wt% of PF127 produced greatest permeate flux of 391 L m⁻² h⁻¹ with minimal fouling. A higher solute rejection of more than 90% was observed for the tailored membranes due to the improvement in surface properties. CONCLUSION: The inherent hydrophilicity of the high density poly (ethylene oxide) brush‐like layer of PF127 at the membrane–water interface is utilized effectively to restrict the adsorption of the organic contaminants onto the membrane surface. After simple hydraulic washing of PAN/PF127 UF membranes, the flux recovery ratio was augmented which is ascribed to their excellent antifouling property and potential use in water treatment. © 2018 Society of Chemical Industry

n-Octanol is a promising biofuel synthesized from biomass with several properties closer to diesel than the more popularly researched n-butanol. This study investigates the effects of injection tim...

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.

Nanostructured conducting polymers are known to function as electroactive materials in sensor devices for adsorption and detection of different analytes. For the purpose of dopamine (DA) detection and CO2 gas adsorption we have prepared nanostructured polypyrrole (PPY) with the help of sodium cholate as surfactant. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) analyses and Brunauer–Emmett–Teller (BET) measurement have been done for the characterization of nanostructure and morphology of the prepared PPY. From the sorption measurement, it is observed that the rodlike PPY structures show highest N2 uptake (91.6 mL g−1) along with appreciable surface area (85.81 m2/g) and porosity (2.53 and 4.51 nm) values. It is also observed that the maximum uptake of CO2 is 173.885 mL g−1 at 195K for the PPY synthesized without any surfactant. Electrochemical characterization of PPY modified glassy carbon electrode (GCE) was done with impedance and cyclic voltammetry experiments. DA sensing in presence of ascorbic acid, uric acid and glucose was done by LSV technique. The PPY modified electrode exhibits sensitivity values of 0.301 and 0.19 μA μM−1 cm2 over two ranges of detection limits of 0.09–0.56 and 10–50 μM for dopamine, respectively (signal/noise = 3).

Sulfonated poly (ether sulfone) (SPES) and poly (vinyl alcohol) (PVA) blend nanocomposite proton exchange membranes were fabricated and tailored with exfoliated tungsten disulfide (E-WS2) nanosheets with the aim of achieving better methanol resistant properties for direct methanol fuel cell (DMFC) applications. Reinforcement due to the existence of E-WS2 nanosheets on composite membrane imparted superior mechanical and thermal stability. Surface morphology of the composite membranes in terms of roughness is examined by AFM. Further, the results confirmed the intercalation of E-WS2 nanosheets onto the polymer matrix. The incorporation of E-WS2 nanosheets onto SPES/PVA system shows highest proton conductivity of 1.18 × 10−2 Scm−1 (at 25 °C) and mechanical stability of 143 MPa upon comparison with pristine SPES membrane. Furthermore, the methanol absorption by membrane matrix is found to be 3.42 × 10−8 cm2s−1. Overall results confirmed that SPES/PVA/E-WS2 nanocomposite proton exchange membranes are promising for applications in DMFCs.

Recently utilization of nanoparticle incorporated polymer membranes for water treatment is in significant consideration. Herein we present the individual effect of graphene oxide (GO) and molybdenum disulfide (MoS2) nanosheets in altering the poly (amide imide) (PAI) membrane's hydrophilicity and thereby its separation efficiency and antifouling ability. The GO was characterized by Field Emission Scanning Electron Microscope (FESEM) and Raman spectroscopy. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction spectroscopy (XRD) were used to probe the existence of GO and MoS2 in PAI nanocomposite membranes. Contact angle (CA), pure water flux (PWF), water uptake, and porosity were measured to evaluate the enhancement in hydrophilicity of nanocomposite membranes. Top surface and cross-section morphology of the membranes were investigated by scanning electron microscopy (SEM). Antifouling capacity of the membranes was evaluated by fouling experiments using bovine serum albumin (BSA) and humic acid (HA) fouling agents. PAI-MoS2 nanocomposite membranes demonstrated better results in enhancing the membrane performance viz., superior PWF (105.6 Lm−2h−1), water uptake (80%) and porosity (21.2%), BSA and HA rejection (95.8 and 93.2%), FRR (90.5%), and slightly reduced hydraulic resistance ( R m ) and more reduced CA (64.8°) than that of PAI-GO nanocomposite membranes. The highly flexible and ultrathin MoS2 nanosheets with greater interaction between Mo and S atoms causes larger macrovoids in the bulk, and the sandwiched structure of MoS2 causes greater permeation. GO also improved PAI matrix to some extent due to its oxygen containing functional groups however several desirable and versatile characteristics of the MoS2 makes the PAI-MoS2 UF membranes as superior performer.

Supported flat sheet nanocomposite polyvinylidenefluoride (PVDF) membranes embedded with hydrophilic TiO2, hydrophobic TiO2, 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 LEPw. Addition of both hydrophilic and hydrophobic NPs demonstrated synergistic effects in terms of both enhanced flux and LEPw 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 TiO2 NPs and 2 wt% of hydrophobic TiO2 NPs (total 7 wt% NPs) was 4.26 kg/m2h with a LEPw 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/m2 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.

An attempt has been made to demonstrate the effects of exfoliated tungsten disulfide (E-WS2) nanosheets on the fabrication, permeation and anti-fouling performance of cellulose acetate (CA) ultrafiltration membranes. The E-WS2 was prepared and characterized in terms of energy dispersive X-ray spectroscopy (EDXS) and X-ray diffraction spectroscopy (XRD). Pure and composite CA membranes were methodically characterized for its surface, chemical and morphological structure using FT-IR, XRD, SEM and water contact angle analysis. Filtration characteristics of membranes such as pure water flux, porosity and hydraulic resistance were also studied. The addition of E-WS2 nanosheets exhibited significant improvement in the surface hydrophilicity of composite membranes than the control CA membrane and are evidenced by the observed contact angle and porosity values. However at 1 wt% E-WS2 concentration, CA membrane showed lower water flux (92.3 ± 0.5) due to the pore plugging effect. The flux recovery ratio (FRR), bovine serum albumin (BSA) rejection, reversible and irreversible fouling experimental results suggested that CA/E-WS2 (1 wt%) UF membranes possess better fouling resistance potential than control CA membrane as a result of enhanced hydrophilicity. This study emphasizes the strong interplay between CA and E-WS2 nanosheets which play a significant role in altering the permeation and antifouling characteristics of nanocomposite membranes.

Exfoliated molybdenum disulfide (E-MoS2) incorporated sulfonated poly ether sulfone (SPES) nanocomposite proton exchange membranes (PEMs) were made by solution casting method. E-MoS2 was synthesized from bulk MoS2 powder by ultrasonication and SPES was prepared by sulfonation of PES using sulfuric and chlorosulfonic acid. Surface characterization of these membranes have been performed using several techniques such as Fourier transformed infra-red spectroscopy, x-ray diffraction, atomic force microscopy, scanning electron microscopy and contact angle measurements. In order to assess the physicochemical performance of the membranes, water uptake, swelling ratio and ion exchange capacity (IEC) of the membranes were measured. Thermal and mechanical stability of the nanocomposite PEMs were probed by thermogravimetric, analysis and tensile strength measurement respectively. Physicochemical characteristics such as water uptake, IEC, swelling ratio, thermal and mechanical stability of SPES/E-MoS2 nanocomposite PEMs were increased upon comparison with the bare SPES PEM. Tensile strength of SPES-1 nanocomposite PEM (117 MPa) is doubled upon comparison with pure SPES PEM (60 MPa). AFM images of PEMs nanocomposite revealed that surface roughness and nodular size were increased upon the addition of E-MoS2. Electrochemical performance of nanocomposite membranes such as proton conductivity, selectivity and methanol permeability were investigated and results confirmed that SPES/E-MoS2 nanocomposite membranes exhibited better performance than bare SPES PEM. More specifically, SPES membrane incorporated with 1 wt% E-MoS2 (SPES-1) exhibited higher proton conductivity (3.17 × 10−3 Scm−1), selectivity (8.43 × 104 Scm−3s) and lower methanol permeability (0.376 × 10−7 cm2s−1). From the results, it is evident that SPES-1 PEM nanocomposites are better candidate for applications in DMFCs.

A series of poly (vinylidene fluoride-co-hexafluoropropylene)/phosphotungstic acid/polypyrrole [SPVdF-co-HFP/PWA/PPY- n, where ‘n’ denotes the number of times the PPY coating process was repeated] composite proton exchange membranes (PEMS) were fabricated and studied for its suitability in direct methanol fuel cells (DMFCs). In situ polymerization was used for the lamination of polypyrrole (PPY) on the SPVdF-co-HFP/PWA membrane surface to diminish the leaching of phosphotungstic acid (PWA). FT-IR analysis confirmed the blending of PWA to SPVdF-co-HFP and the coating of PPY on the composite PEM. AFM study indicated that the surface roughness of the composite membrane was decreased by increasing in PPY layer. Ion exchange capacity, water uptake and swelling ratio of the SPVdF-co-HFP/PWA membranes were decreased whereas tensile strength was increased by increasing the PPY layer. The hydrophobic PPY leads to a substantial drop in methanol crossover with workable levels of proton conductivity. The methanol crossover of SPVdF-co-HFP/PWA/PPY-5 hybrid PEM was found to be 1.73 × 10−7 cm2s−1 and was much lower than Nafion-117 (63 × 10−7 cm2s−1). The selectivity ratio of SPVdF-co-HFP/PWA/PPY-5 was found to be high (2.77 × 104 Scm-3s). Thus, all the experimental results revealed that the SPVdF-co-HFP/PWA/PPY composite membrane could be an alternative to high-priced Nafion.

Electrospun nanofiber composite membranes containing water-stable metal-organic frameworks (MOFs) particles (Zr-based MOF-808) supported on polyacrylonitrile (PAN) nanofiber synthesized via co-electrospinning have been prepared. MOF particles were dispersed in the organic polymer, and their subsequent presence was inferred by scanning electron microscopy. Membrane performance in heavy metal ion adsorption in batch filtration was evaluated on the basis of Cd2+ and Zn2+ ions sequestration. The adsorption capacities of the pristine MOF and the MOF composite membrane revealed that MOF particles in the membrane could be accessed for adsorption in the hydrophilic PAN membranes. The maximum adsorption capacities were 225.05 and 287.06 mg g–1 for Cd2+ and Zn2+, respectively. Conventional thermal activation of pristine MOF and composite membrane revealed a crystal downsizing, while “hydractivation” produced an expanded MOF with enhanced adsorption potentials. The PAN/MOF-808 “hydractivated” composite membrane coul...

Development and commercialization of alternative energy harnessing and storing devices are most necessarily required in today's world. Progressive increase in consumption of energy by the ever-incr...

Non-toxic nanocomposites based bio-films obtained from methylcellulose (MC) can reduce environmental problems associated with synthetic polymers. A new facile route for the isolation of cellulose nano-crystals (CNC) from jute waste is successfully utilized here. The fabrication of CNC reinforced MC nanocomposites by film casting technique and the studies of the effect of CNC on the properties of the MC based nanocomposites have been reported. The synthesized nanocomposites have shown improved UV resistance, mechanical, barrier, and thermal properties. FTIR results established the physicochemical compatibility between the drug, MC and CNC in nanocomposites. In vitro permeation studies performed by using Franz diffusion cell revealed diffusion mediated sustained drug release from the devices due to the presence of interaction between MC and CNC through H-bonding, electrostatic interaction between the hydrophilic polymer/CNC chains with the drug and the formation of tortuous path. The nanocomposites can be used for edible packaging and transdermal drug delivery.

n-Octanol (C8H17OH) is an advanced biofuel derived from ligno-cellulosic biomass that is suitable for compression ignition technology with several properties closer to fossil diesel. This study analyses the performance and emissions of a direct-injection (DI) diesel engine fueled with n-octanol/diesel blends containing 10% (OCT10), 20% (OCT20) and 30%(OCT30) by volume of n-octanol using a 3 × 3 full-factorial experimental design matrix that considers blend composition of n-octanol in diesel, exhaust gas recirculation (EGR) rates of 10%, 15% and 20% and injection timings of 19°, 21° and 23° crank angle (CA) before top dead centre (bTDC) as factors. Models for oxides of nitrogen (NOx), smoke, brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC) were developed using response surface methodology (RSM) and were found to be significant statistically. The variation of EGR had a considerable effect on both BTE and BSFC of the engine followed by blend composition and injection timing. Best performance (BTE = 37.06%, BSFC = 0.23kg/kWh) was delivered by OCT10 at 10% EGR and 23°CA while the lowest performance (BTE = 30.95%, BSFC = 0.28kg/kWh) was by OCT30 at 20% EGR and 19°CA. Injection timing was found to have the highest effect on NOx emissions while EGR affected smoke opacity to the maximum. NOx was found to decrease from 1790 ppm (for OCT10 at 10% EGR and 23°CA) to as low as 410 ppm (for OCT30 at 20% EGR and 19°CA). Smoke opacity was found to decrease from 94.2% (for OCT10 at 20% EGR and 19°CA) to as low as 43% (for OCT30 at 10% EGR and 23°CA). Desirability approach was used to determine the best combination of blend composition of n-octanol, EGR and injection timing for minimising smoke, NOx and BSFC simultaneously. 17% by volume of n-octanol/diesel blend injected at 20° CA bTDC and 10% EGR was predicted to be optimum which delivered a simultaneous reduction of NOx (−47.4%), smoke (−21.08%) and BSFC (−8%) during confirmatory tests with a reasonable accuracy of within 4%. This method is robust and could be employed to other small engines for developing models that can predict engine characteristics with reasonable accuracy.

Poly (m-phenylene isophthalamide) (PMIA) ultrafiltration (UF) membranes has been prepared using lithium chloride (LiCl) and poly (ethylene glycol) of average molecular weight 600 Da (PEG 600) as additives by phase inversion technique. Membranes were characterized by FTIR, TGA, DTG and UTM. Surface characteristics are probed by SEM, AFM and water contact Angle. It was evidenced from SEM analysis that all membranes have macrovoids in its structure and hence possess high water permeability. Accordingly, all membranes were highly hydrophilic in nature which can be predicted from water wettability and work of adhesion measurement using contact angle. Further, membranes were subjected for protein rejection study using bovine serum albumin (BSA) as a model foulant and its fouling ability was analyzed. It has been found that the 10 wt.% PMIA membrane with 2 wt% of PEG 600 and 4 wt.% of LiCl has high water permeability and better reversible and irreversible antifouling capability than any other prepared membranes. Flux recovery ratio (FRR) of 91% was obtained for the 10 wt.% PMIA also confirmed it is one of the promising UF membrane materials.

There is a need for reuse of waste cotton lint (WCL) from the blow room of yarn spinning mills. The drive to use this material for the synthesis of nanocellulose is difficult because of the several purification/pretreatment processes. Here, we developed a combined single bath purification process of WCL and utilized it for the synthesis of nano-crystalline cellulose crystals (NCs) which are valuable nanomaterials with novel properties along with acid recovery for reuse. The micrograph of the synthesized NCs confirmed a network of nano-sized crystalline cellulose crystals having nano ranged diameter of NCs isolated by two processes. The FTIR result established the removal of impurities and hemicelluloses from WCL. The crystallinity index of WCL (∼89.97%) is improved to ∼96% and ∼94% for sulphuric acid and nitric acid synthesized NCs (NC1 and NC2). The crystallite size of WCL, CTWCL, NC1, and NC2 was calculated using XRD and found to be 101.56, 103.54, 98.81, and 95.6nm respectively. The hydrodynamic size (Z-average) (dnm), polydispersity index and zeta potential of NCs was also studied using dynamic light scattering (DLS). The thermal stability of the NC1 is better than that of NC2. These NCs can be used as reinforcing filler/barrier material.

Disposal of waste plastic accumulated in landfills is critical from the environmental perspective. The energy embodied in waste plastic could be recovered by catalytic pyrolysis as waste plastic oil (WPO) and could be recycled as a fuel for diesel engines. This method presents a sustainable solution for waste plastic management as the gap between global plastic production and waste plastic generation keeps widening. The present study investigates the combined influence of EGR and injection timing on the combustion, performance and emission characteristics of a DI diesel engine fueled with neat WPO. Experiments were conducted at three injection timings (21°, 23° and 25°CA bTDC) and EGR rates (10, 20 and 30%) at the engine’s rated power output. When compared to diesel, the combustion event occurred closer to the TDC when the injection timing is delayed from 25°CA bTDC to 21°CA bTDC. The peak in-cylinder pressures and HRRs dropped gradually as the injection timing was delayed from 25°CA bTDC to 21°CA bTDC at all EGR rates. The engine delivered diesel-like fuel consumption with 5.1% higher brake thermal efficiency. NOx decreased up to 52.4% under 30% EGR when WPO was injected lately 21°CA bTDC. Smoke density remained lower by 46% and 9.5% for 10% and 20% EGR rates respectively for WPO only at early injection timing of 25°CA bTDC. HC and CO emissions stayed lower at early injection timing of 25°CA bTDC under 10% EGR. WPO injected at the advanced injection timing of 25°CA bTDC and low EGR rate of 10% was found to simultaneously reduce smoke and NOx by 46% and 38% respectively.