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1.
In this study, the morphology of the nanostructures is evaluated on the surface characterization and performance of the polyacrylonitrile (PAN) ultrafiltration mixed matrix membranes (MMM). To this end, silica nanoparticles (NPs) such as spherical (SiO2) and hexagonal mesoporous (MCM-41) with high hydrophilicity were incorporated at 0.5, 1, and 2 wt%. Attenuated total reflectance-Fourier transform infrared analysis illustrated the placement of NP on the surface of the MMM. Atomic force microscopy studies also showed that SiO2 NP added to PAN exhibited a smoother surface than MCM-41 NP. Field-emission scanning electron microscope analysis of the MMM identified that all membranes are composed of a finger-like porous structure. Contact angle measurements indicate that the morphology of the NPs has no significant effect on MMM hydrophilicity. Moreover, the performance of the MMM was evaluated, and regardless of NP morphology, the MMM showed better permeate flux with increased loading. A higher pure water flux was observed in the PAN-MCM41-1% membrane (237 L/m2 h), possibly because of inherent porosity and high hydrophilicity of MCM-41 compared to SiO2 NP. Further, the PAN-SiO2-1% membrane exhibited superior antifouling properties due to a lower surface roughness. The present studies reveal that the morphology of the NP greatly influence on the structure, permeation, and antifouling properties of PAN membranes.  相似文献   

2.
《Ceramics International》2021,47(23):33172-33179
K2SiF6:Mn4+ (KSF:Mn4+), as an efficient red-emitting phosphor, has a promising application in WLEDs (white light-emitting diodes). However, poor moisture resistance performance still hinders its deeper commercialization. Here, KSF:Mn4+@ CaF2 with high water resistance and luminescent thermal stability has been prepared though H2O2-free hydrothermal method and surface coating process. Both KSF:Mn4+ and KSF:Mn4+@CaF2 all have high luminescent thermal stability, due to negative thermal quenching (NTQ) effect. Mechanism of the NTQ has been discussed and suggested as thermal-light energy conversion mechanism. Compared with KSF:Mn4+, water resistance of KSF:Mn4+@CaF2 is greatly improved by coating of CaF2, because the outer shell of CaF2 can effectively prevent the [MnF6]2- group on the surface of the phosphor from being hydrolyzed into MnO2. The results of water resistance test shows that after immersing in water for 360 min (6 h), luminescent intensity of the uncoated product drops to 41.68% of the initial one, while that of the coated product remains to have 88.24% of its initial one. Warm white light with good luminescent performances (CCT = 3956 K and Ra = 89.3) is got from prototype WLEDs assembled by using the optimal coated sample. The results suggest that the optimal coated sample has potential application in blue-based warm WLEDs.  相似文献   

3.
A series of polyamide thin-film nanocomposite (PA TFN) membranes have been fabricated by incorporating hydrophilic poly(dopamine) (PDA) coated carbon nanotubes (CNTs@PDA) into the PA selective layer via interfacial polymerization. The effects of PDA coating thickness on surface characteristics and separation performances of membranes are studied in detail. The PDA coating makes the surface of PA TFN membrane more hydrophilic, smoother and less electronegative. The desalination performance is obviously influenced by the coating thickness of PDA and the loading concentration of PDA@CNTs. The water fluxes of PDA@CNTs incorporated PA TFN membranes have been improved without sacrificing NaCl rejections. When the loading concentration is 0.0010%, the maximum water flux is 48.1 L m−2 h increasing by 45% compared with that of pristine PA membrane. Meanwhile, the NaCl rejection is up to 99.8%. The CNTs@PDA incorporated PA TFN membranes exhibit better anti-fouling property and separation performance durability. This work proves that CNTs@PDA has great potential application in PA TFN membranes.  相似文献   

4.
《Ceramics International》2020,46(7):8811-8818
K2SiF6:Mn4+ phosphor is well known for its excellent red emission performance which is vital for improving the color rendering of white light-emitting diodes. However, the poor moisture resistance limits its application in optical devices. In this paper, K2SiF6:Mn4+ phosphor is coated with an inorganic hydrophobic protective layer to obtain good moisture resistance. Chemical vapor deposition method was used to decompose acetylene at high temperature, and the generated nanoscale carbon layer worked as a hydrophobic protective coating on the surface of the phosphor. Microstructure, compositions and properties of the synthesized K2SiF6:Mn4+@C phosphor were investigated in detail. It is found that most of the deposited carbon is coated on the surface of phosphor crystals in amorphous state. The carbon atoms are bonded with the fluorine element in K2SiF6:Mn4+ phosphor, forming carbon-fluorine (C–F) covalent bonds. The moisture resistance of K2SiF6:Mn4+@C phosphor is improved owing to the protection of the hydrophobic carbon. The relative emission intensity of K2SiF6:Mn4+@C phosphor could maintain 73% of the initial luminous intensity after immersing in the aqueous solution at room temperature for 8 h, whereas K2SiF6:Mn4+ phosphor without carbon coating was only 0.7% remaining of the initial value under the same conditions.  相似文献   

5.
Novel membranes based on sulfonated poly (phenylene oxide) (SPPO) was developed. SPPO membranes in the hydrogen form were converted to metal ion forms. The effect of exchange with metal ions including monovalent (Li+, Na+, K+), divalent (Mg2+, Ba2+, Ca2+) and trivalent (Al3+) ions was investigated in terms of permeation rate and permeation rate ratios for CO2 and CH4 gases. Both dense homogeneous membranes and thin‐film composite (TFC) membranes were studied for their gas separation characteristics. The effect of membrane preparation conditions and operating parameters on the membrane performance were also investigated. The selectivity of the TFC membrane increased as the cationic charge density increased as a result of electrostatic cross‐linking. TFC membrane of very high selectivity was achieved by coating a thin layer of SPPO‐Mg on a PES substrate. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 735–742, 2000  相似文献   

6.
Novel fluorescent acrylamide hydrogel containing dansyl moiety (DNS-gel) was synthesized via free-radical photopolymerization of acrylamide/N,N′-methylenebisacrylamide by using dansyl chloride as a photoinitiator. DNS-gel presented dual-fluorescence emission when excited at 344 nm in acetonitrile:water (1:1) solvent system due to twisted intramolecular charge transfer between dimethylamino and naphthalene units in the dansyl moiety. Synthesized fluorophore containing gel was utilized as a fluorescent sensor against specific metal ions (Pb2+, Hg2+, Co2+, Cd2+, Mn2+, and Zn2+) and nitroaromatic compounds [1,2-dinitrobenzene, 2,4,6-trinitro-1-phenol [picric acid (PA)], 4-nitrophenol, 2,4,6-trinitrotoluene, 2,4-dinitrophenol (2,4-DNP), and 2-nitrotoluene]. Fluorescence intensity of DNS-gel was diminished by degrees upon the infusion of metal ions and nitroaromatics. For all compounds, the greatest quenching effectiveness was attained in the presence of Co2+ (72.56%), PA (88.55%), and 2,4-DNP, suggesting that DNS-gel could be employed as a potential Co2+, PA, and 2,4-DNP chemical probes. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47096.  相似文献   

7.
Thin-film nanocomposite (TFN) membranes were fabricated by interfacial polymerization of a polyamide (PA) layer on the shell side of hollow fiber membrane supports. TiO2 nanoparticle loadings in the thin-film layer were 0.01, 0.05, and 0.20 wt %. Nanoparticle-free PA thin-film composite (TFC) membranes served as the comparative basis. The TFN membranes were characterized in terms of the chemical composition, structure, and surface properties of the separation layer. Incorporating nanoTiO2 improved membrane permeability up to 12.6-fold. During preliminary laboratory-scale evaluation, TFN membranes showed lower salt rejection but higher TOC rejection in comparisons with the corresponding values for TFC controls. Based on the performance in lab-scale tests, TFN membranes with 0.01 wt % nanoTiO2 loading were selected for an evaluation at the pilot scale with synthetic surface water as the feed. While the permeate flux during long-term pilot-scale operation gradually decreased for TFC membranes, TFN membranes had a higher initial permeate flux that gradually increased with time. The TOC rejection by TFN and TFC membranes was comparable. We conclude that TFN membranes show promise for full-scale surface water treatment applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48205.  相似文献   

8.
Conventionally, electrospun thin‐film composite (TFC) membranes used in protective clothing are fabricated on the basis of an electrospinning substrate coated with a nonporous hydrophilic polymer layer. However, the incompatibility of common coating solvents with inertia substrate materials requires that the support material should be surface‐modified to promote the crosslinking of the dense and porous layers. In this study, we attempted to fabricate a novel TFC membrane for use in protective clothing by the one‐step deposition of poly(vinylidene fluoride) (PVDF) nanofibers onto a dense, hydrophilic thermoplastic polyester elastomer (TPEE) membrane substrate via electrospinning. The proposed approach has the advantage of no need for further surface modification of the substrate membrane. The optimized TFC membrane exhibited a better tensile strength than the dense substrate TPEE film. The testing results for the moisture resistance show that the new TFC membrane had a comparatively high water vapor transmission rate, notwithstanding that the value was slightly lower than that of the single‐layered TPEE film. Simultaneously, a resistance‐in‐series model based on Henis–Tripodi's model for explaining the water vapor permeation behavior of the TFC membrane was proposed. The moisture resistance values predicted by the analyzed model were in good agreement with these experimental data. This verified the validity of this in‐series moisture resistance model for the TFC membrane. The influence of the PVDF porosity on the water vapor permeation resistance throughout the TFC membrane was calculated and is discussed. More work is needed to establish the applicability of the new TFC membrane for lamination with nonwoven fabric to form the multilayered fabrics used in firefighters’ protective clothing. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42170.  相似文献   

9.
Thin-film composite (TFC) membranes comprised of a polyamide (PA) selective layer upon a porous substrate dominate the forward osmosis (FO) membrane market. However, further improvement of perm-selectivity still remains a great challenge. Herein, a polyethyleneimine (PEI) interlayer is intentionally designed prior to interfacial polymerization (IP) to tailor the PA layer, which thus improves the separation performance. The PEI interlayer not only improves the substrate hydrophilicity for adsorbing more diamine monomer and controlling its release rate, but also participates in IP reaction by crosslinking with acyl chloride (TMC). Furthermore, it can decrease the electronegativity of the substrate for decreasing reverse salt diffusion. Consequently, a denser, thinner and smoother PA layer is formed due to the uniform distribution, controllable release of diamine monomer and the extra crosslinking between PEI and TMC. Furthermore, the PA layer becomes more hydrophilic with PEI involvement. As a result, the asprepared TFC membrane exhibits a favorable water flux of 16.1 L m−2 h−1 and an extremely low reverse salt flux (1.25 g m−2 h−1). Meanwhile, it achieves an excellent perm-selectivity with a ratio of water to salt permeability coefficient of 8.25 bar−1. Moreover, it exhibits an outstanding antifouling capacity. The work sheds light on fabricating high perm-selective membranes for desalination.  相似文献   

10.
Ultrafiltration membranes coated with amphiphilic copolymers containing superhydrophilic zwitterionic moieties and hydrophobic POSS moieties (PSM‐coated membranes) are prepared. The free radical polymerization of 2‐(dimethylamino)ethyl methacrylate (DMAEMA) and 3‐(3,5,7,9,11,13,15‐heptaisobutylpentacyclo[9.5.1.13,9.15,15.17,13]octasiloxane‐1‐yl)propyl methacrylate (MAPOSS) monomers is used to prepare a series of copolymers containing different compositions of DMAEMA and MAPOSS units (PDMs). The DMAEMA units in the PDM‐coated membranes are subsequently converted to sulfobetaine methacrylate (SBMA) units using 1,3‐propane sultone (post‐zwitterionization) to give the PSM‐coated membranes. The PSM‐coated membranes show improved fouling resistance/release properties, compared with a neat polysulfone (PSf) membrane. The improved fouling resistance properties of the PSM‐coated membranes are attributed to the superhydrophilic zwitterionic moieties, which form a hydration layer on the membrane surface via electrostatic interactions between the zwitterions and water molecules. Moreover, the total surface energy (γS) value of the PSM‐coated membrane is smaller than that of the PSf membrane due to the hydrophobic POSS moieties. This results in the superior fouling release properties of the PSM‐coated membranes.  相似文献   

11.
A robust and coarse surface mesh was fabricated by introducing a hydrogel coating with interpenetrating polymer network (IPN) structure on stainless steel mesh. The IPN hydrogel was prepared by crosslinking polymerization of acrylic acid (AA) followed by condensation reaction of polyvinyl alcohol (PVA) and glutaraldehyde (GA) at room temperature. As a result, the roughness of modified mesh was enhanced obviously and oil droplet underwater showed a larger contact angle. The hydrogel‐coated surface showed an underwater superoleophobicity with an oil contact angle of 153.92 ± 1.08°. Besides, stable wettability was observed. The mesh can selectively separate oil from water with a high separation efficiency of above 99.8%. This work provides a facile method to strengthen the coating and enhance the efficiency of oil‐water separation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41949.  相似文献   

12.
In this study, the surface grafting of poly(ethylene glycol) (PEG) onto commercial polyamide thin film composite (TFC‐PA) membranes was carried out, using ultraviolet photo‐induced graft polymerization method. The attenuated total reflection Fourier transform infrared spectra verify a successful grafting of PEG onto the TFC‐PA membrane surface. The scanning electron microscope and atomic force microscope analyses demonstrate the changes of the membrane surface morphology due to the formation of the PEG‐grafted layer on the top. The contact angle measurements illustrate the increased hydrophilicity of the TFC‐PA‐g‐PEG membrane surfaces, with a significantly reduced water contact angles compared to the unmodified one. Consequently, the separation performance of the PEG‐grafted membranes is highly improved, with a significant enhancement of flux at a great retention for removal of the different objects in aqueous feed solutions. In addition, the antifouling property of the modified membranes is also clearly improved, with the higher maintained flux ratios and the lower irreversible fouling factors compared to the unmodified membrane. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45454.  相似文献   

13.
In this paper, maleic anhydride is directly coated on the surface of SrAl2O4: Eu2+, Dy3+ (SAO‐ED) phosphors by an interfacial coordination chemistry method. Fourier transform infrared spectroscopy (FTIR), X‐ray photoelectron spectra (XPS), X‐ray diffraction (XRD), and scanning electron microscopy (SEM) methods are used to characterize the coating. The experimental result shows that a dense coating layer is consisting of maleic anhydride coordination with metal ions on the surface of the phosphors and the coating process does not destroy the crystal structure of the phosphors. It is also found that the introduction of maleic anhydride does not change the excitation and emission spectra of SAO‐ED phosphors, but decreases the luminous intensity, which is verified by the photoluminescence (PL) measurement. Afterglow delay curves show that the initial brightness of coated SAO‐ED phosphors decreases, but the afterglow decay rate of coated phosphors is slower than that of uncoated phosphors after they both are immersed into water for one month. This indicates that the coating layer protects the phosphors and the crystal structure of coated phosphors in water was not destroyed.  相似文献   

14.
《Ceramics International》2023,49(16):27024-27029
Mn4+-activated fluoride is one of the most important red phosphors for white light-emitting diodes (WLEDs) with high color rendering index (CRI). Due to a lack of water resistance, their potential applications are limited. Although surface coating strategies improve the waterproof stability of fluoride red phosphors, they have downsides. It was found that Nb5+ plays an important role in improving the water resistance of Mn4+-activated oxyfluorides by preventing the hydrolysis of [MnF6]2-. In this work, the influence of Nb5+ on the waterproof stability of Mn4+-activated fluorides was explored. A set of synthesized K2Ta1-xNbxF7:Mn4+ phosphors exhibit tunable and superior water resistance. The photoluminescence (PL) intensity of the representative sample K2Ta0.6Nb0.4F7:5%Mn4+ remains nearly 100% of its initial value even after being immersed in water for 60 min, which is significantly higher than the commercial K2SiF6:Mn4+ red phosphor (8.7%). Our findings open up new possibilities for the development of waterproof fluoride red phosphors.  相似文献   

15.
ZnO was coated on LiNi0.5Co0.25Mn0.25O2 cathode (positive electrode) material for lithium ion battery via sol–gel method to improve the performance of LiNi0.5Co0.25Mn0.25O2. The X-ray diffraction (XRD) results indicated that the lattice structure of LiNi0.5Co0.25Mn0.25O2 was not changed distinctly after surface coating and part of Zn2+ might dope into the lattice of the material. Energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) proved that ZnO existed on the surface of LiNi0.5Co0.25Mn0.25O2. Charge and discharge tests showed that the cycle performance and rate capability were improved by ZnO coating, however, the initial capacity decreased dramatically with increasing the amount of ZnO. Differential scanning calorimetry (DSC) results showed that thermal stability of the materials was improved. The XPS spectra after charge–discharge cycles showed that ZnO coated on LiNi0.5Co0.25Mn0.25O2 promoted the decomposition of the electrolyte at the early stage of charge–discharge cycle to form more stable SEI layer, and it also can scavenge the free acidic HF species from the electrolyte. The electrochemical impedance spectroscopy (EIS) results showed ZnO coating could suppress the augment of charge transfer resistance upon cycling.  相似文献   

16.
The present investigation deals with studies on novel magnetic resonance signal‐enhancing coating materials. The polyaminocarboxylate complexes of Gd3+ as side chains were prepared by the conjugation of N‐(2‐hydroxyethyl)ethylenediaminetriacetic acid (HEDTA) with poly(styrene‐maleic acid) copolymer (SMA). The complexation of the Gd3+ ion to the conjugates was carried out by adding GdCl3 to the solution of the polymer ligands. The resulting Gd3+‐containing polymer complexes were characterized by GPC, FTIR, NMR, and inductively coupled plasma–Auger electron spectroscopy, which confirmed that HEDTA was covalently attached to SMA and Gd3+‐containing polymer complexes were formed. The PP catheters were coated with the Gd3+‐containing polymer complexes and characterized by XPS. The result confirms that the Gd3+ complexes were coated on the surface of PP catheters. In the relaxation test, the relaxation rates of the water proton in the vicinity of the coated PP catheter surface increase significantly, suggesting that Gd3+‐containing polymer complex coating materials show great MR enhancement of water proton, and potentialities in making catheters used for endovascular interventions or therapy, visible by MRI. The influence of protein on the relaxation rates of coated PP catheter shows that the protein adsorption on the catheter surface influences the enhancement of the MR signal for the coating materials of Gd3+‐containing polymer complex. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1358–1364, 2003  相似文献   

17.
We, for the first time, employed chemically stable covalent organic framework (COF) (TpPa-1) as a transport-active phase within the polymer (styrene-butadiene rubber; SBR) matrix to make TpPa-1@SBR thin-film composite (TFC) membranes. Three composite membranes, viz., TpPa-1(30)@SBR, TpPa-1(50)@SBR, and TpPa-1(70)@SBR have been prepared with varying COF content. These membranes were characterized for gas permeance and results were compared with the pristine SBR-based TFC membrane. The fully organic nature of chemically stable COF offered good compatibility with the host polymer matrix (SBR) and resulted into flexible TFC membranes even at 70% of COF loading; compared to the other porous material (MOFs or Inorganic fillers), it is appreciable.  相似文献   

18.
《Ceramics International》2015,41(4):5537-5546
A new kind of composite mica pigments were prepared by coating Co2−xMxTiO4 composite oxide nanoparticles onto mica, to investigate the effects of doping ions Mg2+, Mn2+, Ni2+, Cu2+ and Zn2+ on the properties of the doped composite pearlescent pigments, such as the crystal structure, color and shading power. The structure, morphology, color and shading power of the coated pigments were characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis spectrophotometer and CIE L*a*b* methods. SEM images of coated pigments showed that mica were coated uniformly with a single layer of dispersed nanoparticles. Research of the doped composite pigments showed that the doping ions had entered into the spinel crystal structure, forming a new kind of composite mica pearlescent pigments coated with Co2−xMxTiO4. For the analysis of color and shading power of the pigments, doping of Ni2+ and Zn2+ can improve the color and shading power of the doped pigments, but the larger dosage of Zn2+ doping can weaken the color and shading power of the doped pigments. Doping of Mg2+, Mn2+ and Cu2+ metal ions can also weaken the color and shading power of the doped pigments.  相似文献   

19.
The inner and outer surfaces of a porous hollow fiber polysulfone support are compared as substrates for the synthesis of polyamide thin-film composite (TFC) membranes by interfacial polymerization. While both surfaces have pores common of microfiltration membranes, the inner surface has a larger pore diameter than the outer surface (2,700 nm compared to 950 nm). The inner TFC membrane showed higher water nanofiltration permeance than the outer (2.20 ± 0.17 compared to 0.13 ± 0.03 L m−2 hr−1 bar−1). This was due to the influence of the porosity and roughness, which were different on both support surfaces. These membranes are interesting because they were synthesized in a hollow fiber support with a high membrane area per volume unit (~6,900 m2/m3) and the substrate used was commercial, which means that the TFC membrane obtained is suitable for industrial application. A mathematical simulation of the nanofiltration run with COMSOL Multiphysics 5.3 software confirmed the experimental trends observed.  相似文献   

20.
This research reported developing a polyethersulfone (PES) membrane using covalent organic frameworks (COFs) nanoparticle with a mean dimension of 30 nm. The SNW-1 (Schiff-based network) COF was synthesized using precursors of melamine and terephthalic acid and then characterized by XRD, SEM, TEM, and FTIR analyses. The influence of different loadings of the COF was evaluated on the permeability, antifouling behavior and dye/salt rejection. The addition of SNW-1 caused a reduction in surface roughness and an improvement in hydrophilicity of the nanocomposite membranes, which improved their flux and fouling resistance considerably. The improvement of water flux, 2.6 times, was observed by adding 0.5 wt% COF to the membrane matrix. The 0.5 wt% COF membrane presented the best water permeability, 38.9 L/m2 h bar BSA solution flux, dye rejection of 98.7% for Reactive Green 19 and 62.6% for Reactive yellow 39, 52.9% Na2SO4 and 24.5% NaCl salt rejections. Zeta potential and salt rejection trend indicated a negative surface charge on the nanocomposite membrane. Fouling experiments by BSA protein solution exhibited that the FRR reached 88.9% for 2 wt% COF membrane. Thus, employing SNW-1 into PES matrix resulted in a promising nanofiltration membrane for dye separation and moderate salt separation with suitable antifouling properties.  相似文献   

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