Nanoparticle Composite Membranes Research Articles

Polyamide 6-Al2O3 nanoparticle composite nanofiber membranes with high solar reflectivity and human radiation transmittance for passive human body cooling

Passive radiant heat management is an energy-saving thermal radiation management technology that can improve the temperature regulation of conventional clothing in high-temperature environments. However, existing materials are either complex in structure, difficult to fabricate, or unsuitable for human application. In this study, a novel nanofiber membrane was developed that exhibits high solar reflectance and infrared transparency to human radiation, thus having an excellent radiative cooling effect. The nanofiber membrane was prepared by electrospinning polyamide (PA) 6 containing Al2O3 nanoparticles. It exhibits an average solar radiation reflectance of about 88 %, a maximum reflectance of more than 95 %, and transmittance to the human body infrared of more than 95 % and provides a cooling effect of 4–6.4 °C for outdoor objects (with convection), which results from the coaction of PA6 nanofibers and Al2O3 nanoparticles. The implementation of nanofiber membranes in clothing could not only protect wearers from high outdoor temperatures but also improve air and moisture permeability. We hope that this unique nanofiber membrane will be useful for managing thermal comfort and energy efficiency in various applications ranging from architectural materials to personal cooling solutions.

Recycled Cellulose Acetate/Cerium Vanadate Nanoparticles Composite Membranes with Tuned Ultraviolet and Blue Light Shielding Capabilities

Recycled Cellulose Acetate/Cerium Vanadate Nanoparticles Composite Membranes with Tuned Ultraviolet and Blue Light Shielding Capabilities

Stabilized superhydrophobic composite membranes prepared by electrospinning for oil–water separation

AbstractIn dealing with the oil–water separation process, improving the oil–water selectivity of the membrane surface and increasing the porosity within the membrane are effective means to achieve durable and efficient oil–water separation. Therefore, polystyrene/polyacrylonitrile‐polyvinylidene fluoride/Polydimethylsiloxane Fe3O4 nanoparticles (PS/PAN‐PVDF/PDMS@Fe3O4) composite membranes with superhydrophobicity and lipophilicity were prepared by electrospinning technique. By controlling the filling concentration of Fe3O4 nanoparticles, a stable superhydrophobic and lipophilic rough structure was constructed, and micro–nano multilayer rough voids existed inside the membrane. The results showed that the composite fiber membrane exhibited exceptional superhydrophobicity (156.2°), thermal stability (338°C), mechanical properties (tensile strength of 3.0 MPa, elongation of 33.9%), and oil adsorption capacity (30–100 g/g). Moreover, even under corrosive environments, this composite fiber membrane maintained its superhydrophobic properties (above 152°) and achieved high oil–water separation efficiency (above 97%). Remarkably, after 40 cycles, the composite membrane could sustain a separation flux of 5000 L m−2 h−1. Consequently, the composite fiber membrane manufactured using this strategy exhibits promising potential for applications in oil–water separation.

Preparation of superhydrophobic membranes with ultraviolet‐absorbing capacity for oil–water separation by electrospinning

AbstractTo address the escalating issue of oily wastewater, separation membranes with special wettability on the surface are widely used in oil–water separation. The development of separation membranes with not only stable separation flux but also anti‐fouling properties is an urgent problem. Therefore, polystyrene/polyacrylonitrile‐polyvinylidene fluoride/polydimethylsiloxane‐titanium dioxide nanoparticle (PS/PAN‐PVDF/PDMS@TiO2) composite membranes with superhydrophobicity and lipophilicity were prepared by electrospinning technique. By changing the doping amount of TiO2 nanoparticles, the multilevel rough structure was constructed on the surface, and the transformation of the Ti–O–C chemical bond to the Si–O–Ti chemical bond was realized inside the composite membrane. The results showed that the composite membrane had excellent superhydrophobicity (154.9°) and mechanical properties (tensile strength of 3.54 MPa, elongation of 60.95%). The membrane can absorb ultraviolet light and exhibits enhanced resistance to fouling when exposed to visible‐UV light. Additionally, the composite membrane demonstrates an adsorption capacity of 30–100 g/g for a wide range of oils. In corrosive environments, the composite membrane maintains superhydrophobicity (above 150°) and achieves high oil–water separation efficiency (97%). After 40 cycles, the separation flux of 6000 L.h−1 m−2 can be maintained. Hence, superhydrophobic oleophilic composite membranes with a stable separation flux and resistance to fouling can be employed in the field of oil–water separation.Highlights PS/PAN‐PVDF/PDMS@TiO2 composite membrane with multilevel rough structure. PS/PAN‐PVDF/PDMS@TiO2 composite membrane with excellent UV absorption and self‐cleaning ability. PS/PAN‐PVDF/PDMS@TiO2 composite membrane with stable oil–water separation efficiency in harsh environments.

Inhibition of Coliforms and Escherichia coli Bacterial Strains in Water by 3D Printed CS/GO/AgNP Filtration Membranes

The effect of 3D printed modified Chitosan membranes on bacterial strains by water filtration system was explored in this study. Specifically, it focused on the characterisation of 3D printed Chitosan–graphene oxide–silver nanoparticles (CS–GO–AgNP) composite membranes and the effects of Dimethylacetamide (DMAc) used as co-solvent on the performance of the CS–GO–AgNP nanocomposites. It also examined the impact of GO–AgNP on the CS matrix for inhibition of Fecal Coliforms, Total Coliforms and Escherichia coli (E. coli) bacterial strains in contaminated surface water. The increase in DMAc concentration and subsequent reduction in CS mole fraction within the ink formulation resulted to wider distribution of AgNP across membrane surface, improvement in mechanical strength and surface hydrophilicity of the modified CS membranes. Similarly, increase in GO–AgNP concentration effectively reduced the spread of the identified microorganisms. Sample B-12 with 79% CS, 21% DMAc and 1.2 ml of GO–AgNP exhibited the highest inhibition of the bacterial strains, with more than 95% of Fecal and Total Coliforms suppressed or inactivated, while 99.9% of the E. coli bacterial cells were completely prevented, indicating that our 3D printed modified CS membranes can effectively be used for water treatment.

Preparation of a Flexible Reduced Graphene Oxide-Si Composite Film and Its Application in High-Performance Lithium Ion Batteries

This paper describes a strategy for preparing free-standing reduced graphene oxide@Si nanoparticles (rGO@Si NPs) composite membranes. Graphene oxide (GO) was reduced and self-assembled synchronously with nanoparticles of silicon (Si NPs) on a metal surface and the composite film was subsequently used in a lithium-ion battery (LIB). This work describes several important novel aspects of the reported technology. Firstly, the composite membrane has a flexible self-supporting structure, allowing it to function as an anode material without requiring binders and current collectors. Secondly, the successful assembly of Si NPs and reduced Graphene oxide (rGO) sheets has enabled the production of the rGO@Si NPs composite film with high controllability and orderliness. Thirdly, the conductive nature of graphene has significantly decreased the resistivity while enhancing the electron transport capacity of the battery anode. Lastly, the robust and flexible structure of the graphene sheet has greatly mitigated the large volume variation in Si NPs during charging or discharging, resulting in the rGO@Si NPs composite film exhibiting excellent energy density and high-power density.

Regulating the thickness of nanofiltration membranes for efficient water purification.

Fabrication of an organic polymer nanofiltration membrane with both high water permeability and high salt rejection is still a big challenge. Herein, phytic acid (PhA)-modified graphene oxide (GO) was used as the membrane thickness modifier, which was introduced into the thin-film nanoparticle composite (TFN) membrane via in situ interfacial polymerization (IP) on a porous substrate. The water flux of the optimally tuned TFN-GP-0.2 composite membrane is 48.9 L m-2 h-1, which is 1.3 times that of the pristine thin-film composite (TFC) nanofiltration membrane (37.9 L m-2 h-1) (GP represents the PhA modified GO composite). The rejection rate of 2000 ppm MgSO4 for TFN-GP-0.2 membranes was maintained at 97.5%. The increased water flux of the TFN-GP composite membrane compared to that of the TFN nanofiltration membrane was mainly attributed to enhanced hydrophilicity and reduced thickness of the polyamide (PA) layer. Molecular dynamics (MD) simulations confirm that the diffusion rate of amine monomers is reduced by the presence of a GP complex in the IP process, which facilitates the formation of PA layer with thinner thickness. In addition, the TFN-GP-0.2 composite membrane also showed good long-term stability; after 12 h of continuous operation, the water flux only decreased by 0.1%. This study sheds new light on the development of GO-based nanofiltration for potential implementation, as well as a unique concept for manufacturing high-performance nanofiltration membranes.

Thin Films Based on Polyimide/Metal–Organic Framework Nanoparticle Composite Membranes with Substantially Improved Stability for CO2/CH4 Separation

Thin Films Based on Polyimide/Metal–Organic Framework Nanoparticle Composite Membranes with Substantially Improved Stability for CO₂/CH₄ Separation

Preparation and optical properties of Au nanoparticle “Sandwich” structure (AuNPs/ZNNs/AuNPs) substrate based on ZnO nanosheets template

Surface enhancement Raman scatting (SERS) substrate was synthesized by two-step electrodeposition method based on ZnO nanosheets (ZNNs) template. ZNNs membrane was prepared via first-electrodeposition by using zinc nitrate hexahydrate (ZnNO3•6H2O) as the precursor. Subsequently, an Au seed layer was coated on the ZNNs membrane substrate using ion sputtering apparatus. Finally, Au nanoparticles composite membrane was obtained by the second-electrodeposition growth process of Au nanoparticles in chlorogenic acid (HAuCl4•4H2O) solution. The Au nanoparticles composite membrane could be served as an activity SERS substrate, and it showed that ZNNs are mutually hinged and grow vertically ITO substrate and Au nanoparticles grew along the (111) crystalline orientation. Results demonstrate that Au nanoparticles with an average diameter of 50 nm are uniformly deposited on the surface of ZNNs template, and the as-prepared AuNPs/ZNNs/AuNPs “sandwich” structures membrane was a high activity and sensetivity SERS substrate, it showed a rather low detection limitation of 10−12 mol/L for R6G solution.

Composite polymer electrolyte membrane decorated with porous titanium oxide nanotubes for fuel cell operating under low relative humidity

A block copolymer composite membrane of sulfonated poly(arylene ether sulfone ketone) (SPESK) decorated with porous hygroscopic titanium oxide nanotubes (TNT) is designed and fabricated for low relative humidity (RH) operating polymer electrolyte fuel cells (PEFCs). The SPESK-TNT composite membrane in a PEFC operated at 100% RH, and 80 °C resulted in about 1.3 and 1.1-folds higher power density in comparison with the benchmark Nafion (NRE-212) and pristine SPESK membranes at 0.6 V. Further, operating under 30% RH and 80 °C, the SPESK-TNT composite membrane generates 3.8 and 2.8-folds improved power density in comparison with the pristine SPESK and commercial NRE-212 membranes, respectively, at 0.6 V. An outstanding improvement of PEFC performance using SPESK-TNT composite membrane also maintains relative to a SPESK-TiO2 nanoparticles composite membrane, operating under 100 and 30% RH. Moreover, the SPESK-TNT composite membrane shows a stable operating potential of more than 200 h at 30% RH and 80 °C, confirming the durable PEFC operation. The enhanced PEFC performance under dry conditions is mainly the result of improving water management by the TNT filler in the membrane and cathode catalyst utilization, yielding significantly suppressing both ohmic and mass transport overpotentials.

Pressure Sensors: Cross‐Linked Gold Nanoparticle Composite Membranes as Highly Sensitive Pressure Sensors (Adv. Funct. Mater. 40/2020)

Pressure Sensors: Cross‐Linked Gold Nanoparticle Composite Membranes as Highly Sensitive Pressure Sensors (Adv. Funct. Mater. 40/2020)

Cross‐Linked Gold Nanoparticle Composite Membranes as Highly Sensitive Pressure Sensors

AbstractIn this article, highly sensitive differential pressure sensors based on free‐standing membranes of cross‐linked gold nanoparticles are demonstrated. The nanoparticle membranes are employed as both diaphragms and resistive transducers. The elasticity and the pronounced resistive strain sensitivity of these nanometer‐thin composites enable the fabrication of sensors achieving high sensitivities exceeding 10−3 mbar−1 while maintaining an overall small membrane area. Furthermore, by combining micro‐bulge tests with atomic force microscopy and in situ resistance measurements the membranes’ electromechanical responses are studied through precise observation of the concomitant changes of the membranes’ topography. The study demonstrates the high potential of free‐standing nanoparticle composites for the fabrication of highly sensitive force and pressure sensors and introduces a unique and powerful method for the electromechanical investigation of these materials.

Manufacture of a Hydrophobic Silica Nanoparticle Composite Membrane for Oil-Water Emulsion Separation

Manufacture of a Hydrophobic Silica Nanoparticle Composite Membrane for Oil-Water Emulsion Separation

Graphene Oxide Nanofiltration Membranes Containing Silver Nanoparticles: Tuning Separation Efficiency via Nanoparticle Size.

Three types of graphene oxide/silver nanoparticles (GO/AgNPs) composite membranes were prepared to investigate size-effect of AgNPs on nanofiltration ability. The size of AgNPs was 8, 20, and 33 nm, which was characterized by UV-visible spectroscopy and transmission electron microscopy. The morphology and structure of GO and GO/AgNPs composite membranes were characterized by atomic force microscopy, scanning electron microscopy, and X-ray diffraction. The filtration performance of membranes were evaluated on a dead-end filtration device. When the size of AgNPs is 20 nm, the GO/AgNPs composite membrane has the highest water flux (106.1 L m−2 h−1 bar−1) and rejection of Rhodamine B (RhB) (97.73%) among three types of composite membranes. The effect of feed concentration of dye solution and the flux of common solvent was also investigated. The mechanism was discussed, which demonstrated that both interlaying spacing and defect size influence the filtration ability of membrane, which is instructive to future study.

Synthesis of Poly (Vinylidene Fluoride)/Modified SBA-15 Nanoparticles Composite Membrane for Water Purification

One of the methods of pollution separating from urban and industrial wastewater is the use of composite membranes based on polymer. The modified composite polymer has high mechanical resistance and improved heat, which is an appropriate option to use as a membrane infiltration method. In this study, to improve the polymer membrane of polyvinylidene fluoride (PVDF) is used the modification of mesoporous silica nanoparticles (SBA–15). The mesoporous silica nanoparticles (SBA-15) are made by the sol-gel method witch in this method is using a precursor of Tetra-ethyl-ortho silicate (TEOS) in the presence of a copolymer Pluronic P123 (as mould and for maintaining the structure after solvent exiting) and has been calcined at 600 °C. The surface modifies of SBA-15 is used from (3-chloropropyl) trimethoxysilane and Triron-100 for 24 h in the presence of argon gas by the post-synthesis method. Subsequently, the physical characteristics are investigated by using nitrogen adsorption and desorption analysis (BET), scanning electron microscope (SEM), Fourier transforms infrared spectroscopy (FTIR), thermal analysis (TGA) and X-ray diffraction pattern (XRD). The FT-IR analysis and thermal analysis confirmed the complete transmitting of mould during thermal operation. So, according to the results of nitrogen absorption and desorption, powders synthesized based on IUPAC categorization, have hysteresis IV which confirms cavities in the area of meso. Accordingly, the specific surface of the samples is 640 m2.g−1, the volume of cavities is 1.2 cm3.g−1 and the diameter of cavities is 6.2 nm. Moreover, the BJH graph indicated the cavities with a narrow size distribution. The results showed that adding a small amount of modified SBA-15 nanoparticles to PVDF can effectively increase the membrane’s hydrophilicity, mechanical properties, antifouling performance, and thermal stability, increase membrane flux and salt rejection.

Catalytic degradation of TCE by a PVDF membrane with Pd-coated nanoscale zero-valent iron reductant

Trichloroethylene (TCE) has serious threat to ecosystem. Fe-Pd nanoparticles (NPs) are good materials for catalytic degradation of TCE but still face severe challenges including easy fouling, agglomeration, deactivation and difficult separation and reuse etc. To overcome these drawbacks, we have constructed a novel structured PVDF/Fe-Pd NPs composite membrane with nanosized surface pores to execute the TCE degradation. Results indicate the degradation shows pseudo first-order reaction kinetics and high degradation rate in the static state degradation. Furthermore, the degradation ability can be enhanced by increasing Fe and Pd contents, the degradation temperature or decreasing the degradation pH value. However, the degradation is essentially limited by the diffusion. Thus, the cross-flow degradation is further applied to promote the diffusion. By this operating model, the degradation ability of the composite membrane can be greatly improved. More importantly, the reactants always keep the purity in the membrane surface side and can be controlled to enter the membrane pore for catalytic degradation. Thus, products can be timely discharged via the membrane pores and the side reactions between reactants and products can be largely reduced. In addition, the nanosized surface pores can also prevent the Fe-Pd NPs from being fouled. In a word, the novel composite membrane shows strong degradation ability, good stability and convenient operating ability for the TEC catalytic degradation.

Self-enriched mesoporous silica nanoparticle composite membrane with remarkable photodynamic antimicrobial performances

Mesoporous silica nanoparticle (MSN) demonstrates great potentials as a loading platform for bactericidal agents, but may be limited by its application form of bulk or powder. Herein, we developed MSN surface-enriched composite membranes with remarkable photodynamic antimicrobial activities via a facile electrospinning method. The mixture of zein and polycaprolactone (PCL) was served as the polymeric matrix, while the methylene blue (MB) loaded MSN was modified by trichloro (1H, 1H, 2H, 2H-heptadecafluorodecyl) silane (THFS) and acted as reactive oxygen species (ROS) generator to exert their antimicrobial performances. Owing to its low surface energy, the fluorinated MSN tended to be enriched on the surface of the nanofiber, hence significantly enhancing the ROS generation. Moreover, benefiting from the surface enrichment of the fluorinated nanoparticles, the composite membrane displayed obvious surface hydrophobicity and exhibited discernible bacterial repellency. Subsequently, upon visible light (660 nm) irradiation, the composite membrane demonstrated remarkable photodynamic antibacterial activities against Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) but without essential detrimental impacts on the mammalian cells. We envision that this self-enriched MSN composite membrane may find broad applications in bacterial infection-resistant areas.

High‐performance composite photocatalytic membrane based on titanium dioxide nanowire/graphene oxide for water treatment

ABSTRACTIn this study, a novel dopamine‐modified TiO2 nanowire (NW)‐intercalated graphene‐oxide‐based photocatalytic (NWC) membrane was prepared by vacuum‐assisted filtration using a commercial cellulose acetate membrane as a support layer. At the same time, compared with the synthesized reduced graphene‐oxide/polydopamine/TiO2 nanoparticle composite (NPC) membrane, it was found that the NWC membrane has high water flux (273 L m−2 h−1) and removal rate (above 98%) on the dye‐oil emulsion. After 5 cycles of experiments, the NWC membrane maintained a relatively stable permeation flux and removal rate, which was significantly better than the NPC membrane. The results showed that the NWC membrane had a more uniform distribution of TiO2 NW, and had better antifouling ability, recyclability, and photocatalytic performance than NPC membrane. In summary, the NWC photocatalytic membrane of this study shows excellent water purification potential and provides a new path for photocatalytic water treatment. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48488.

Non-Resorbable Nanocomposite Membranes for Guided Bone Regeneration Based On Polysulfone-Quartz Fiber Grafted with Nano-TiO2.

The polymer-inorganic nanoparticles composite membranes are the latest solutions for multiple physicochemical resistance and selectivity requirements of membrane processes. This paper presents the production of polysulfone-silica microfiber grafted with titanium dioxide nanoparticles (PSf-SiO2-TiO2) composite membranes. Silica microfiber of length 150–200 μm and diameter 12–15 μm were grafted with titanium dioxide nanoparticles, which aggregated as microspheres of 1–3 μm, applying the sol-gel method. The SiO2 microfibers grafted with nano-TiO2 were used to prepare 12% polysulfone-based nanocomposite membranes in N-methyl pyrrolidone through the inversion phase method by evaporation. The obtained nanocomposite membranes, PSf-SiO2-TiO2, have flux characteristics, retention, mechanical characteristics, and chemical oxidation resistance superior to both the polysulfone integral polymer membranes and the PSf-SiO2 composite membranes. The antimicrobial tests highlighted the inhibitory effect of the PSf-SiO2-TiO2 composite membranes on five Gram (-) microorganisms and did not allow the proliferation of Candida albicans strain, proving that they are suitable for usage in the oral environment. The designed membrane met the required characteristics for application as a functional barrier in guided bone regeneration.

The Current-Voltage Properties of Ch/AgNP Composite Membranes: A Study on the Effect of AgNP Content

In this study, we report the properties of current-voltage (I-V) of Ch/AgNP (chitosan/silver nanoparticles) composite membranes with emphasis on the effect of the content of AgNP. Composite membranes were made by a casting method using chitosan as matrix, 1% acetic acid as solvent and AgNP as filler. The content of AgNP added was 10, 100, 250, 500, 750 and 1000 μg. The I-V measurements were conducted using a two-compartment cell, which contains two working electrodes and two Ag/AgCl reference electrodes. The electrolyte solutions used were KCl and CaCl2 with a concentration of 0.025 M. All measurements were done at room temperature of ± 28 °C. Also, it has been conducted FTIR analysis. The results showed that the absorbance peak of the -OH group in composite membranes are sharper compared with Ch membrane and also it has been observed peaks of Ag-O metal oxide at around 671 and 507 cm-1. The I-V curve of the composite membranes in the range 0.66-0.98 mA is ohmic. The conductance of the composite membranes is smaller than that of Ch membranes, it decreased as increased the content of AgNP added, and it is greater in the KCl solution than in CaCl2 solution.