Preparation of mesoporous poly (acrylic acid)/SiO2 composite nanofiber membranes having adsorption capacity for indigo carmine dye

Mesoporous poly (acrylic acid)/SiO₂ (PAA/SiO₂) composite nanofiber membranes functionalized with mercapto groups were fabricated by a sol-gel electrospinning method, and their adsorption capacity for indigo carmine was investigated. The membranes were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, x-ray powder diffraction (XRD), and nitrogen adsorption–desorption measurement. SEM and TEM observation results showed that the PAA/SiO₂ fibers had diameters between 400–800 nm and mesopores with an average pore size of 3.88 nm. The specific surface area of the mesoporous nanofiber membranes was 514.89 m²/g. The characteristic peaks for mercapto group vibration in FTIR and Raman spectra demonstrated that the mercapto groups have been incorporated into the silica skeleton. The adsorption isotherm data of indigo carmine on the membranes fit well with Redlich–Peterson model, and the maximum adsorption capacity calculated was 523.11 mg/g. It was found that the removal rate of indigo carmine by the membranes reached a maximum of 98% in 90 min and the adsorption kinetics followed a pseudo-second-order model. The high adsorption capacity of PAA/SiO₂ nanofiber membrane makes it a promising adsorbent for indigo carmine removal from the wastewater.     

Hydrophilic modification of polyethersulfone porous membranes via a thermal-induced surface crosslinking approach

A thermal-induced surface crosslinking process was employed to perform a hydrophilic surface modification of PES porous membranes. Difunctional poly(ethylene glycol) diacrylate (PEGDA) was used as the main crosslinking modifier. The addition of trifunctional trimethylolpropane trimethylacrylate (TMPTMA) into the reaction solutions accelerated the crosslinking progress of PEGDA on PES membranes. The membrane surface morphology and chemical composition were characterized by scanning electron microscopy (SEM) and FTIR-ATR spectroscopy. The mass gains (MG) of the modified membranes could be conveniently modulated by varying the PEGDA concentration and crosslinking time. The measurements of water contact angle showed that the hydrophilicity of PES membranes was remarkably enhanced by the coating of crosslinked PEGDA layer. When a moderate mass gain of about 150 μg/cm² was reached, both the permeability and anti-fouling ability of PES membranes could be significantly improved. Excessive mass gain not only contributed little to the anti-fouling ability, but also brought a deteriorated permeability to PES membranes.     

Composite Ni-Co-fly ash coatings on 5083 aluminium alloy

Ni-Co-fly ash coatings were deposited on zincate treated 5083 wrought aluminium alloy substrates with the aid of the electrodeposition technique. Structural and chemical characterization of the produced composite coatings was performed with the aid of X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron dispersive X-ray analysis (EDS) techniques. The Ni-Co-fly ash coatings were found to consist of a crystalline Ni-Co solid solution with dispersed fly ash particles. In addition, chemical analysis of the Ni-Co matrix showed that it consisted of 80 wt.% Ni and 20 wt.% Co. The co-deposition of fly ash particles leads to a significant increase of the microhardness of the coating. The corrosion behaviour of the Ni-Co-fly ash/zincate coated aluminium alloy, in a 0.3 M NaCl solution (pH = 3.5), was studied by means of potentiodynamic corrosion experiments.     

Development of high performance nano-porous polyethersulfone ultrafiltration membranes with hydrophilic surface and superior antifouling properties

Hydrophilic nano-porous polyethersulfone ultrafiltration membranes were developed for milk concentration. The membranes were prepared from new dope solution containing polyethersulfone (PES)/polyvinylpirrolidone (PVP)/polyethyleneglycole (PEG)/cellulose acetate phthalate (CAP)/acrylic acid/Triton X-100 using phase inversion induced by immersion precipitation technique. This casting solution leads to formation of new hydrophilic membranes. The morphological studies were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). In addition, the hydrophilicity and performance of membranes were examined by contact angel measurements and cross-flow filtration (pure water flux, milk water permeation, protein rejection and antifouling measurements). The contact angle measurements indicate that a surface with superior hydrophilicity was obtained for PES membranes. Two concentrations of PES (16 and 14.4 wt.%) and two different non-solvents (pure water and mixtures of water and IPA) were used for preparation of membranes. The morphological studies showed that the higher concentration of PES and the presence of IPA in the gelation media results in formation of a membrane with a dense top and sub-layer with small pores on the surface. The pure water flux of membranes was decreased when higher polymer concentration and mixtures of water and IPA were employed for membrane formation. On the other hand, the milk water permeation and protein rejection were increased using mixtures of water and IPA as non-solvent. Furthermore, the fouling analysis of the membranes demonstrated that the membrane surface with fewer tendencies for fouling was obtained.     

Effect of TiO2 nanoparticle size on the performance of PVDF membrane

The comparison of the performance and morphology was carried out between neat PVDF membrane and PVDF composite membranes with nanosized TiO₂ particles of different size. The results of permeability and instrumental analysis illustrated that nanometer size obviously affected the performance and structure of the PVDF membranes. The smaller nanoparticles could improve the antifouling property of the PVDF membrane more remarkably. The surface and cross-section of the membranes were observed with an atomic force microscopy (AFM), a scanning electron microscope (SEM). The TiO₂/PVDF membrane with smaller nanoparticles had smaller mean pore size on its surface and more apertures inside the membrane. X-ray diffraction (XRD) experiments also suggested that smaller TiO₂ nanoparticles had stronger effect on the crystallization of PVDF molecules.     

Novel PdAgCu ternary alloy: Hydrogen permeation and surface properties

Dense PdAgCu ternary alloy composite membranes were synthesized by the sequential electroless plating of Pd, Ag and Cu on top of both disk and tubular porous stainless steel substrates. X-ray diffraction and scanning electron microscopy were employed to study the structure and morphology of the tested samples. The hydrogen permeation performance of these membranes was investigated over a 350-450 °C temperature range and a trans-membrane pressure up to 100 kPa. After annealing at 500 °C in hydrogen stream followed by permeation experiments, the alloy layer presented a FCC crystalline phase with a bulk concentration of 68% Pd, 7% Ag and 25% Cu as revealed by EDS. The PdAgCu tubular membrane was found to be stable during more than 300 h on hydrogen stream. The permeabilities of the PdAgCu ternary alloy samples were higher than the permeabilities of the PdCu alloy membranes with a FCC phase. The co-segregation of silver and copper to the membrane surface was observed after hydrogen permeation experiments at high temperature as determined by XPS.     

多孔氧化铝膜上自组织生长Sn纳米点阵列的研究

以多孔阳极氧化铝膜(porous anodic alumina, PAA)为基片，采用真空电子束蒸发的方法在多孔氧化铝膜上制备了高度有序度的Sn纳米点阵列.锡纳米点阵的XRD与块体锡的完全相同，扫描电镜(SEM)测试结果表明，所制备的金属Sn纳米点阵与阳极氧化铝膜的多孔阵列具有完全相同的有序结构，阵列中每个Sn纳米粒子的形状为球形的，其直径接近于PAA膜的孔直径.对Sn纳米点阵形成过程和形成机理进行了讨论.     

Effect of ECAP consolidation process on the interfacial characteristics of Al-Cu-Ti metallic glass reinforced aluminum matrix composite

Equal channel angular pressing (ECAP) process was used to consolidate the Al₆₅Cu₂₀Ti₁₅ metallic glass (AMG) reinforced Al matrix composite at high temperature. The matrix/reinforcement interfacial microstructure of the consolidated composite was studied using scanning electron microscopy (SEM) equipped with energy-dispersive spectrometer (EDS) and transmission electron microscopy (TEM). It is demonstrated that the mutual diffusion of elements was occurred between the matrix and glass reinforcement during the consolidation process. The imposed severe plastic strains by the ECAP process affected the mutual diffusion and elemental distribution at the interface. Also, microstructural characterizations confirmed that no reaction products have been formed between the matrix and reinforcement particles. An illustrative model was presented to explain the atomic structure of matrix/reinforcement interface region.     

Analysis of confiscated fireworks using Raman spectroscopy assisted with SEM‐EDS and FTIR

A forensic analysis of several samples of pyrotechnic artefacts was performed by Raman spectroscopy assisted by scanning electron microscopy/energy‐dispersive X‐ray spectroscopy (SEM‐EDS) and Fourier transform infrared (FTIR) analysis. Among the components, several nitrates, ammonium perchlorate, nitrocellulose, metallic titanium particles and shellac were detected. The combination of Raman spectroscopy and SEM‐EDS showed very useful performance. All components were detected by Raman spectroscopy except for shellac, kaolinite and titanium particles, which were not conclusive enough and had to be determined by FTIR and EDS. In contrast, many compounds were not detected by FTIR. Copyright © 2011 John Wiley & Sons, Ltd.     

Microstructure of Ni/YSZ cermets according to particle size of precursor powders and their anodic performances in SOFC

Four different Ni/YSZ cermets were prepared by combining two sets of NiO and YSZ powders of different size. The microstructural change evolved during the course of electrode adhesion and cell operation was monitored using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The anodic activity was compared by analyzing the ∝ impedance spectra of four Ni/YSZ cermet (H₂) / YSZ half cells at 1000 °C. Among the cermets, the one that prepared from the smaller NiO and larger YSZ powder showed the best anodic performances on aspects of the initial activity and long-term stability. This favorable performance is partly responsible to the presence of larger YSZ particles which provide a supporting matrix to suppress the microstructural change against Ni sintering and concomitant volume shrinkage, and partly to an easy formation of Ni channel for electronic conduction. Anodic performances of the other cermets were also discussed based on their microstructure.     

Composite membranes of sulfonated poly(phthalazinone ether ketone) doped with 12-phosphotungstic acid (H3PW12O40) for proton exchange membranes

Sulfonated poly(phthalazinone ether ketone) (SPPEK) and 12-phosphotungstic acid (PWA) composite membranes were prepared by the casting procedure, using SPPEK solution blended with PWA. The physicochemical properties of these composite membranes were studied by means of field-emission scanning electron microscopy (FSEM), X-ray diffraction (XRD) analysis, thermogravimetry analysis (TGA) and Fourier transform infrared attenuated total reflection (FTIR-ATR) spectroscopy. The PWA particles in composite membranes are stable due to the interaction between SO₃H group of SPPEK and PWA particles. The proton conductivity of the composite membrane containing 10% PWA reaches the maximum of 0.17 S/cm at 80 °C under 100% relative humidity.     

Sonocatalytic degradation and catalytic activities for MB solution of Fe treated fullerene/TiO2 composite with different ultrasonic intensity

Fe-fullerene/TiO(2) composite catalysts were prepared with titanium (IV) n-butoxide (TNB) by a sol-gel method. The samples were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), specific surface area (BET), X-ray diffraction analysis (XRD) and energy dispersive X-ray spectroscopy (EDX). The catalytic activities were evaluated by the catalytic oxidation of methylene blue (MB) solution. XRD patterns of the composites showed that the Fe-fullerene/TiO(2) composite contained a typical single and clear anatase phase. The surface properties shown by SEM present a characterization of the texture on Fe-fullerene/TiO(2) composites and showed a homogenous composition in the particles for the titanium sources used. The EDX spectra for the elemental identification showed the presence of C and Ti with strong Fe peaks for the Fe-fullerene/TiO(2) composite. The degradation of MB solution by ultrasonic irradiation in the presence of Fe-fullerene/TiO(2) compounds was investigated in complete darkness. With the increase in the amount of Fe, the degradation rate of methylene blue solution also increased.     

Surface functionalization of porous ZrO2-TiO2 membranes using γ-aminopropyltriethoxysilane in palladium electroless deposition

A pre-treatment technique was developed to facilitate the electroless deposition of Pd layers onto ZrO₂-TiO₂ ceramic membrane surfaces in the preparation of novel multi-functional porous membranes. Surface functionalization using an aqueous solution of γ-aminopropyltriethoxysilane (γ-APTES) aided the surface immobilization of the Pd activation particles and the subsequent electroless deposition of metal layers onto the hydroxyl-rich membrane surface. The attractiveness of γ-APTES functionalization, in the electroless deposition of metal layers, was thus demonstrated. Characterization techniques employed in the structural study of the surface-modified membranes included SEM, EDS, dynamic analysis in micro-PIXE, and XRD. Special membrane techniques such as electrokinetic analysis and single-gas permeation measurements were also used in the study of surface modification. These membranes were developed for application in tasks associated with the hydrogen economy.     

Effect of MgO formation in the vicinity of Ni-SDC/LSGM interface on SOFC performance

An interfacial reaction between Ni-SDC anodes and the LSGM electrolyte was investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to clarify its effect on the SOFC performance. Highly resistive fine particles were formed in the vicinity of the Ni-SDC/LSGM interface as a result of the reaction between Ni and LSGM. TEM/EDX analyses revealed that these particles were MgO, which has a much lower electronic conductivity than Ni. The particles were localized on the surface of the Ni grains in the Ni-SDC anodes. The effect of MgO particle formation on the SOFC performance depended on the anode thickness. The particles significantly increased the area-specific ohmic resistance of thin anodes (less than 15 μm), but they hardly increased the resistance of thick anodes at all.     

Electron-assisted chemical etching of oxidized chromium

Electron-assisted chemical etching of oxidized chromium, CrO_x, has been studied by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and atomic force microscopy (AFM). Two model substrates were used—10 nm CrO_x deposited on Si(1 0 0) that was covered with either native oxide or a 20 nm Au/Pd alloy film. Using chlorine and/or oxygen as etching gases, the experiments were conducted in a customized high vacuum system, equipped with a high density electron source and a low pressure reaction cell. On both substrates, electron-assisted chemical etching of CiO_x was detected by SEM, EDS and AFM. Making the method questionable for etching applications, there is substantial substrate damage associated with the etching. The SEM images indicate strongly inhomogeneous material removal, apparently initiated and propagated from specific but unidentified sites. In the experiments involving the Au/Pd film, there was phase separation of Au and Pd, and dewetting to form metallic islands. AFM data show that the etched holes were as deep as 200 nm, confirming relatively rapid etching of the Si substrate after the top layer of Cr oxide was removed.     

Polymethylmethacrylate/Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> composite nanofiber membranes with ultra-low dielectric permittivity

Ultra-low dielectric permittivity poly (methyl methacrylate)/Fe₃O₄ composite fiber membranes have been successfully prepared using electrospinning. The composite membranes were characterized by SEM (scanning electron microscopy), TEM (transmission electron microscopy), FT-IR (Fourier transform infrared), XRD (X-ray diffraction) and a radio frequency (RF) impedance/capacitance material analyzer. The magnetic measurement showed that the composite membranes displayed the super-paramagnetic property. The results showed that the dielectric permittivity of the composite fiber membranes was decreasing with increasing Fe₃O₄ nanoparticle content.     

Pluronic P123 assisted synthesis of hollow InSn/In2O3 hybrid nanoparticles by solution dispersion

A detailed analysis of the optimum regimes of pulsed current metal electrodeposition into pores of porous anodic alumina PAA is presented. A simple model based on cathodic and anodic current transients is developed. The model is based on a simplified equivalent circuit consisting of two capacities related to the barrier and porous parts of porous anodic alumina. Nanowires of Cd, Zn, In, Ni, Co, Ag, and Cu were embedded into PAA by pulsed electrodeposition using an asymmetric rectangular ac signal. Deposited metal nanowires were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), optical spectroscopy, Auger electron spectroscopy (AES), and X-ray diffractometry (XRD).     

The influence of sulfonated polyethersulfone (SPES) on surface nano-morphology and performance of polyethersulfone (PES) membrane

In this research, firstly sulfonation of polyethersulfone (PES) was carried out and then polyethersulfone (PES)/sulfonated polyethersulfone (SPES) blend membranes were prepared with phase inversion induced by immersion precipitation technique. polyvinylpyrrolidone (PVP, 2 wt% concentration) was added in the casting solution as pore former. SPES was characterized by FT-IR and UV-visible spectra, ion exchange capacity and swelling ratio. The characterization of SPES polymer indicates that the sulfonic acid groups were produced on PES polymer. Also, the prepared PES/SPES blend membranes were characterized by contact angle, AFM, SEM and cross-flow filtration for milk concentration. The contact angle measurements indicate that the hydrophilicity of PES membrane is enhanced by increasing the SPES content in the casting solution. The SEM and AFM images show that the addition of SPES in the casting solution results in a membrane with larger surface pore size and higher sub-layer porosity. The mean pore size of the membrane increased from 98 nm for PES membrane to 240 and 910 nm for 50/50 and 0/100 PES/SPES blend membranes, respectively. The pure water flux and milk water permeation through the prepared membranes are increased by blending PES with SPES. Moreover, the protein rejection of PES/SPES blend membranes was lower than PES membrane.     

Iron oxide nanoparticle synthesis in aqueous and membrane systems for oxidative degradation of trichloroethylene from water

The potential for using hydroxyl radical (OH^?) reactions catalyzed by iron oxide nanoparticles (NPs) to remediate toxic organic compounds was investigated. Iron oxide NPs were synthesized by controlled oxidation of iron NPs prior to their use for contaminant oxidation (by H₂O₂ addition) at near-neutral pH values. Cross-linked polyacrylic acid (PAA) functionalized polyvinylidene fluoride (PVDF) microfiltration membranes were prepared by in situ polymerization of acrylic acid inside the membrane pores. Iron and iron oxide NPs (80–100 nm) were directly synthesized in the polymer matrix of PAA/PVDF membranes, which prevented the agglomeration of particles and controlled the particle size. The conversion of iron to iron oxide in aqueous solution with air oxidation was studied based on X-ray diffraction, Mössbauer spectroscopy and BET surface area test methods. Trichloroethylene (TCE) was selected as the model contaminant because of its environmental importance. Degradations of TCE and H₂O₂ by NP surface generated OH^? were investigated. Depending on the ratio of iron and H₂O₂, TCE conversions as high as 100 % (with about 91 % dechlorination) were obtained. TCE dechlorination was also achieved in real groundwater samples with the reactive membranes.     

The removal of sodium dodecylbenzene sulfonate surfactant from water using silica/titania nanorods/nanotubes composite membrane with photocatalytic capability

This paper reports experimental results on removal of sodium dodecylbenzene sulfonate (SDBS), using silica/titania nanorods/nanotubes composite membrane with photocatalytic capability. This multifunctional composite membrane has been successfully prepared from colloidal X-silica/titania sols (X denotes molar percent of silica) by the sol-gel technique. The prepared nanorods/nanotubes composite membranes were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), scanning probe microscope (SPM) and UV-vis diffuse reflectance spectra (DRS). XRD patterns confirmed that the embedding of amorphous silica into nanophase titania matrix helped to increase the thermal stability of titania and control the size of titania particles. The small size titania particles with anatase phase played an important role in formation of silica/titania nanorods/nanotubes composite membranes with photocatalytic capability. The percentage of anatase phase titania reached 93% when 20%-silica/titania nanorods/nanotubes composite membrane calcined at 400 °C for 2 h. Most (95%) of the pore volume was located in mesopores of diameters ranging from 1.4 to 10 nm. The experimental results showed that the removal of SDBS achieved 89% after 100 min by combining the photocatalysis with membrane filtration techniques. Although the SDBS was not completely decomposed by photocatalysis, the degradation of the SDBS helped to enhance composite membrane flux and prevent membrane fouling. It was possible to treat successfully surfactant wastewater using multifunctional silica/titania nanorods/nanotubes composite membrane by means of a continuous process; this could be interesting for industrial applications.