Effect of TiO2 nanoparticles on the surface morphology and performance of microporous PES membrane

PES-TiO₂ composite membranes were prepared via phase inversion by dispersing TiO₂ nanopaticles in PES casting solutions. The crystal structure, thermal stability, morphology, hydrophilicity, permeation performance, and mechanical properties of the composite membranes were characterized in detail. XRD, DSC and TGA results showed that the interaction existed between TiO₂ nanopaticles and PES and the thermal stability of the composite membrane had been improved by the addition of TiO₂ nanopaticles. As shown in the SEM images, the composite membrane had a top surface with high porosity at low loading amount of TiO₂, which was caused by the mass transfer acceleration in exposure time due to the addition of TiO₂ nanopaticles. At high loading amount of TiO₂, the skinlayer became much looser for a significant aggregation of TiO₂ nanopaticles, which could be observed in the composite membranes. EDX analysis also revealed that the nanoparticles distributed in membrane more uniformly at low loading amount. Dynamic contact angles indicated that the hydrophilicity of the composite membranes was enhanced by the addition of TiO₂ nanopaticles. The permeation properties of the composite membranes were significantly superior to the pure PES membrane and the mean pore size also increased with the addition amount of TiO₂ nanopaticles increased. When the TiO₂ content was 4%, the flux reached the maximum at 3711 L m⁻² h⁻¹, about 29.3% higher than that of the pure PES membrane. Mechanical test also revealed that the mechanical strength of composite membranes enhanced as the addition of TiO₂ nanopaticles.     

Enhanced electrochemical performance of porous activated carbon by forming composite with graphene as high-performance supercapacitor electrode material

In this work, a novel activated carbon containing graphene composite was developed using a fast, simple, and green ultrasonic-assisted method. Graphene is more likely a framework which provides support for activated carbon (AC) particles to form hierarchical microstructure of carbon composite. Scanning electron microscope (SEM), transmission electron microscope (TEM), Brunauer–Emmett–Teller (BET) surface area measurement, thermogravimetric analysis (TGA), Raman spectra analysis, XRD, and XPS were used to analyze the morphology and surface structure of the composite. The electrochemical properties of the supercapacitor electrode based on the as-prepared carbon composite were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), charge/discharge, and cycling performance measurements. It exhibited better electrochemical performance including higher specific capacitance (284 F g^?1 at a current density of 0.5 A g^?1), better rate behavior (70.7% retention), and more stable cycling performance (no capacitance fading even after 2000 cycles). It is easier for us to find that the composite produced by our method was superior to pristine AC in terms of electrochemical performance due to the unique conductive network between graphene and AC.     

Preparation of Symmetric Network PVDF Membranes for Protein Adsorption via Vapor-Induced Phase Separation

Symmetric network poly(vinylidene fluoride) (PVDF) membranes without a dense skin layer were prepared by vapor-induced phase separation from a PVDF/N,N-dimethylacetamide (DMAc)/water system. The effects of evaporation atmosphere, temperature, and humidity during the preparation of the membranes on their morphologies were investigated by scanning electron microscope (SEM). With low temperature and high humidity, the polymer crystallization mechanism dominated the membrane formation process, and the casting solution formed membranes with symmetric morphologies in the vapor phase containing 0.79% DMAc. The effect of additives on the membrane structure and performance was also investigated. The results of adsorption experiments showed that the binding capacity of bovine serum albumin (BSA) increased with the appearance of a circular network morphology and the decrease of mean pore size of the membrane. With the addition of LiCl to the casting solution, the obtained membrane can adsorb BSA up to 150 μg/cm². Proteins on sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis gels were successfully electro-blotted onto these PVDF membranes. Compared with commercial membranes, the PVDF membranes prepared in this work were more suitable for protein blotting.     

Effect of hot pressing on the ionic conductivity of the PEO/LiCF3SO3 based electrolyte membranes

PEO/LiCF₃SO₃ (LiTFS) /Ethylene carbonate (EC) polymer electrolyte membranes were prepared with a solution casting method followed by a hot pressing process. The effect of the hot pressing process on the in-plane conductivity of the PEO electrolyte membranes was evaluated using a four-electrode AC impedance method. The composition, morphology, and microstructure of the composite polymer electrolyte were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The AC impedance measurement results indicate that the hot pressing process can increase the room temperature conductivity of the membranes 14 times to 1.7 × 10^− 3 S cm^− 1 depending upon the duration of the hot pressing process. The SEM, FTIR, XRD, and DSC results indicate that the hot pressing process could increase the amorphous part of the polymer electrolyte membrane or convert large spherulite crystals into nano-sized crystals.     

SiMn–Graphite composites as anodes for lithium ion batteries

Two Si–Mn–C composites were obtained by sequentially ball milling the mixture of the silicon and manganese powders (atomic ratio of 3:5), followed by addition of 20 wt.% and 10 wt.% graphite, respectively. The phase structure and morphology of the composite were analyzed by X-ray diffraction (XRD) and scanning electromicroscopy (SEM). The results of XRD show that there is no new alloy phase in the composite obtained by mechanical ball milling. SEM micrographs confirm that the particle size of the Si–Mn–C composite is about 0.5–2.0 μm and the addition of graphite restrains the morphological change of active center (Si) during cycling. The Si–Mn particles are dispersed among the carbon matrix homogeneously, which ensures a good electrical contact between the active particles. Electrochemical tests show that the Si–Mn–C composite achieves better reversible capacity and cycleability. The Si–Mn–20 wt.% C composite electrode annealed at 200 °C for 2 h reveals an initial reversible capacity of 463 mAh·g^− 1 and retains 387 mAh·g^− 1 after 40 cycles.     

Results of potential exposure assessments during the maintenance and cleanout of deposition equipment

This study is a compilation of results obtained during the cleanout of deposition equipment such as chemical vapor deposition or physical vapor deposition The measurement campaigns aimed to evaluate the potential exposure to nanoaerosols in the occupational environment and were conducted in the workspace. The characterization of aerosols includes measurements of the concentration using condensation particle counters and measurements of the size distribution using fast mobility particle sizer, scanning mobility particle sizer, and electrical low pressure impactor (ELPI). Particles were sampled using collection membranes placed on the ELPIs stages. The samples were analyzed with an SEM?CEDS to provide information including size, shape, agglomeration state, and the chemical composition of the particles. The majority of the time, no emission of nanoparticles (NPs) was measured during the use of the molecular deposition equipment or when opening the chambers, mainly due to the enclosed processes. On the other hand, the maintenance of the equipment, and especially the cleanout step, could induce high concentrations of NPs in the workplace following certain processes. Values of around 1 million particles/cm³ were detected with a size distribution including a high concentration of particles around 10?nm.     

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.     

Preparation and characterization of hexagonal boron nitride and PAMPS-NMPA-based thin composite films and investigation of their membrane properties

The preparation, thermal, morphological, and ion-conducting properties of new composite membranes based on poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) and nitrilotri(methylphosphonic acid) (NMPA)/hexagonal boron nitride (hBN) were carried out throughout this work. Fourier transform infrared (FTIR) spectroscopy was used to characterize the interactions between host polymer, NMPA, and inorganic additive, hBN. Thermal properties of the materials were examined by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) tests. TGA results illustrated that all composite membranes are thermally stable up to 200 °C. The surface topography of the films was investigated by scanning electron microscopy (SEM) and verified that hBN uniformly dispersed into the PAMPS-NMPA matrix. The crystallinity of the membranes was characterized by using X-ray diffraction (XRD). X-ray patterns support semicrystalline nature of the composite materials. At anhydrous conditions, the maximum proton conductivity was found as 3.2?×?10^?5 S cm^?1 at 150 °C for PAMPS-NMPA-3hBN via impedance analyzer.     

核桃果皮基活性炭的氯化锌活化制备及工艺优化

以核桃果皮为原料,以氯化锌为活化剂,采用正交设计,马弗炉加热法制备了核桃果皮基活性炭,并对所得活性炭进行表征,测定了不同实验条件下制备的核桃果皮基活性炭的得率、比表面积和碘吸附值,对最优条件下制备的活性炭进行了孔径分析、红外光谱分析,Boehm法测定其表面酸性基团含量等。实验结果表明：以氯化锌为活化剂制备核桃果皮基活性炭的最佳工艺参数分别为：活化温度600 ℃,活化时间1 h,氯化锌浓度50%,粒径大小为60目。最优条件下制备的活性炭比表面积达到1 258.05 m2·g-1,中孔率为32.18%,说明核桃果皮可以制备出比表面积高的优质活性炭,不但实现了农业废料的资源化,还解决了农业废料污染的问题,同时提供了廉价的吸附剂,对于开辟活性炭原料的新来源具有重要意义。     

Nickel–cobalt oxide/activated carbon composite electrodes for electrochemical capacitors

Nanostructured synthesis of nickel–cobalt oxide/activated carbon composite by adapting a co-precipitation protocol was revealed by transmission electron microscopy. X-ray diffraction analysis confirmed that nickel–cobalt oxide spinel phase was maintained in the pure and composite phases. Cyclic voltammetry, galvanostatic charge–discharge tests and ac impedance spectroscopy were employed to elucidate the electrochemical properties of the composite electrodes in 1.0 M KCl. The specific capacitance which was the sum of double-layer capacitance of the activated carbon and pseudocapacitance of the metal oxide increased with the composition of nickel–cobalt oxide before showing a decrement for heavily-loaded electrodes. Utilisation of nickel–cobalt oxide component in the composite with 50 wt. % loading displayed a capacitance value of ～59 F g^?1. The prepared composite electrodes exhibited good electrochemical stability.     

A novel composite anode for LIB prepared via template-like-directed electrodepositing Cu–Sn alloy process

A novel composite anode material consisted of electrodeposited Cu–Sn alloy dispersing in a conductive micro-porous carbon membrane coated on Cu current collector was investigated. The composite material was prepared by template-like-directed electrodepositing Cu–Sn alloy process and then annealing. The template-like microporous membrane electrode was obtained as follows: (1) casting a polyacrylonitrile (PAN) solution on a copper foil, (2) then immersing the copper foil into deionized water for phase inversion, and (3) drying the membrane electrode. This method provided the composite material with high decentralization of Cu–Sn alloy and supporting medium function of conductive carbon membrane deriving from pyrolysis of PAN. SEM, XRD, and EDS analysis confirmed this structure. The characteristic structure was beneficial to inhibit the aggregation among Cu–Sn microparticles, to relax the volume expansion during cycling, and to improve the cycle ability of electrode. The reversible charge/discharge capacity of the composite material remained more than 426.6 and 445.1 mAh g⁻¹, respectively, after 70 cycles, while that of the electrode prepared by electrodepositing Cu–Sn on a bare Cu foil decreased seriously to only 11.3 mAh g⁻¹. These results show that the novel preparing anode process for LIB is a promising method and can achieve composite materials with larger specific capacity and long cycle life.     

Reduced methanol crossover and enhanced proton transport in nanocomposite membranes based on clay−CNTs hybrid materials for direct methanol fuel cells

Hybrid nanomaterial based on the combination between a 2D silicate structure of a smectic clay (SWy) and 1D structures of carbon nanotubes has been synthesized and used as additive in the polymer matrix of Nafion for the preparation of electrolyte nanocomposite membranes. The CNTs anchored on the clay’s lamellae were subsequently oxidized and organo-functionalized by sulphonic groups. The hybrid membranes have been tested in direct methanol fuel cells (DMFCs) and studied by NMR spectroscopy (pulse field gradient technique and relaxation times), electrochemical impedance spectroscopy and SEM microscopy. The study of the molecular dynamics of methanol and protons, as well as the tests in the DMFC, shows the effectiveness of these “branched particles” for the reduction of the methanol crossover, whilst ensuring appropriate proton conductivity, especially in conditions of low humidity and high temperature (>100 °C).     

Poly(Butylene Terephthalate)/Single Wall Carbon Nanotubes Composite Nanofibers by Electrospinning

Poly(buthylene terephthalate)(PBT)/single wall carbon nanotubes (SWCNTs) composite nanofibers were prepared by electrospinning. The effect of carbon nanotubes on the morphology, crystallization, and mechanical properties of the electrospun composite nanofibers were investigated by SEM, DSC, and tensile testing, respectively. SEM observations indicated that the presence of SWCNTs resulted in finer nanofibers for lower loading; however, a broader distribution, especially for the higher diameter ranges was found for nanofibers with higher amounts of carbon nanotubes. SWCNTs accelerated crystallization and acted as a nucleating agent; the degree of crystallinity increased with increasing content of SWCNTs, followed by a moderate decrease at higher content. Specific tensile strength and modulus of the PBT/SWCNTs composite nanofibers mats were higher than that of neat PBT nanofibers mat. However, the elongation at break of composite nanofibers mats was lower than that of the neat PBT nanofibers mat.     

Preparation and characterization of asymmetric polyethersulfone and thin-film composite polyamide nanofiltration membranes for water softening

In this research, two types of nanofiltration membranes were prepared and evaluated for water softening. Their nanofiltration performance was evaluated by cross-flow filtration using NaCl (1 g/l) and MgSO₄ (1 g/l) solution at 5 and 10 bar, 25 °C and 10 l/min. The morphological studies were performed with SEM and AFM instruments. In addition, the hydrophilicity of membranes was examined by contact angle measurements. In the first type, asymmetric polyethersulfone (PES) nanofiltration membranes were prepared using phase inversion induced by immersion precipitation technique. Different components such as polyvinylpyrrolidone (PVP), polyethyleneglycole (PEG), acrylic acid and Triton X-100 were used as additive in the PES casting solution, which lead to the formation of new asymmetric nanofiltration membranes. Two concentrations of PES (20 and 25 wt%) and two different non-solvents (pure water and mixture of water (80 vol.%) and IPA (20 vol.%)) were used for preparing asymmetric nanofiltration membranes. The morphological studies showed that the membranes prepared with non-solvent containing 20 vol.% IPA have smoother surface and smaller pores in surface and sub-layer compared to membranes prepared with pure water as non-solvent. The flux was decreased when higher polymer concentration and mixture of water and IPA were employed for membrane formation. However, NaCl and MgSO₄ rejections were improved. In the second type, thin-film composite polyamide nanofiltration membrane was fabricated using interfacial polymerization of 1,3-phenylenediamine (PDA) with trimesoyl chloride (TMC). A rough and dense film was formed on the PES support membrane by interfacial polymerization. The water permeability of composite membrane was 7 and 21 kg m⁻² h⁻¹ at 5 and 10 bar, respectively. Moreover, the rejection to the MgSO₄ as divalent salt (85 and 90%) was high compared to the NaCl as monovalent salt (64 and 67%).     

Hybrid laser—magnetron technology for carbon composite coating

Hybrid laser- magnetron deposition system was developed and tested for study of carbon based thin film coatings. Various geometrical configurations and deposition conditions were tested. Films of TiC, TiCN, and SiC were synthesized. Films were fabricated in argon (TiC), in argon/nitrogen (TiCN), or in argon/hydrogen ambient (SiC films). Film properties were studied by SEM, XRD, GDOES, and XPS. Smooth, homogeneous film over the area of 9 cm² were prepared. Crystalline TiC films were grown at room substrate temperature.     

Zn-ZrO2 nanocomposite coatings: Elecrodeposition and evaluation of corrosion resistance

The Zn and Zn-ZrO₂ composite coatings were produced by electrodeposition technique using sulphate bath. ZrO₂ particles were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The ZrO₂ particle size distribution in the plating bath and Zeta potential and the ZrO₂ were measured using dynamic light scattering technique (DLS). The corrosion resistance properties of Zn and Zn-ZrO₂ composite coatings were compared by examining the experimental data acquired through polarization, open circuit potential (OCP) and Tafel measurements. The corrosion environment was 3.5 wt% NaCl solution. The variation of amount of ZrO₂ in the solution on their % wt inclusion in the composite and on composite microhardness was investigated. XRD patterns were recorded for Zn and Zn-ZrO₂ coatings to compare their grain size. The SEM images of coatings before and after corrosion under chemical and electrochemical conditions were presented. The results were analyzed to establish the superiority of Zn-ZrO₂ composite over Zn coating.     

Controlling the micropore size of activated carbons for the treatment of fuels and combustion gases

Exclusively microporous activated carbons have been prepared from cork by physical and chemical activation under different conditions. The results show that it is possible to control the pore size of the activated carbons and to obtain materials with narrow micropore size (≥0.69 nm) and high micropore volume (≤0.64 cm³ g⁻¹) equal to or better than the best activated carbon fibres. Higher micropore volumes are generally obtained by chemical activation at higher temperature using dry or potassium hydroxide impregnation. On the other hand, wet or carbonate impregnation, as well as high temperature, or physical activation with CO₂ or H₂O under appropriate conditions, favours low mean pore widths.     

Cyclodextrin metal–organic framework by ultrasound-assisted rapid synthesis for caffeic acid loading and antibacterial application

Cyclodextrin metal–organic framework by ultrasound-assisted rapid synthesis for caffeic acid (CA) loading and antibacterial application (U-CD-MOF) was successfully studied and this method shortened the preparation time to a few minutes. It was found that the ultrasonic power, reaction time and temperature would affect the morphology and size of the obtained crystal. Under the optimal conditions, U-CD-MOF had a cubic structure with uniform size of 8.60 ± 1.95 μm. U-CD-MOF was used to load the antibacterial natural product CA to form the composite (CA@U-CD-MOF) and the loading rate of CA@U-CD-MOF to CA could reach 19.63 ± 2.53%, which was more than twice that of γ-CD. Various techniques were applied to characterize the synthesized crystal, including Powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and N₂ adsorption. In addition, antibacterial tests were performed on the obtained crystal. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of CA@U-CD-MOF for Escherichia coli O157: H7 (E. coli O157: H7) were both 25 mg·mL⁻¹, and the MIC for Staphylococcus aureus (S. aureus). was 25 mg·mL⁻¹. The sustained release behavior of CA@U-CD-MOF to CA in ethanol fitted well to Higuchi model and the loading of CA was supported by molecular docking results. In general, U-CD-MOF was successfully achieved by ultrasound-assisted rapid synthesis and the obtained crystal was further evaluated for potential antibacterial application.     

Controllable Formation of Niobium Nitride/Nitrogen‐Doped Graphene Nanocomposites as Anode Materials for Lithium‐Ion Capacitors

Niobium nitride/nitrogen‐doped graphene nanosheet hybrid materials are prepared by a simple hydrothermal method combined with ammonia annealing and their electrochemical performance is reported. It is found by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) that the as‐obtained niobium nitride nanoparticles are about 10–15 nm in size and homogeneously anchored on graphene. A non‐aqueous lithium‐ion capacitor is fabricated with an optimized mass loading of activated carbon cathode and the niobium nitride/nitrogen‐doped graphene nanosheet anode, which delivers high energy densities of 122.7–98.4 W h kg^?1 at power densities of 100–2000 W kg^?1, respectively. The capacity retention is 81.7% after 1000 cycles at a current density of 500 mA g^?1. The high energy and power of this hybrid capacitor bridges the gap between conventional high specific energy lithium‐ion batteries and high specific power electrochemical capacitors, which holds great potential applications in energy storage for hybrid electric vehicles.     

Preparation and performance of polysulfone-sulfonated poly(ether ether ketone) blend ultrafiltration membranes. Part I

Ultrafiltration membranes were prepared from blends with polysulfone (PSf) and sulfonated poly(ether ether ketone) (SPEEK) by phase inversion technique. The blend membranes were prepared with polymer composition from 0 to15 wt%. Sulfonated poly(ether ether ketone) was used to improve the performance and permeability of blended membranes. The effects of polymer composition on compaction, pure water flux, water content, and membrane hydraulic resistance were studied. The membranes were also subjected to the determination of pore statistics and molecular weight cut-off (MWCO) determination studies by using different molecular weight of proteins. The porosity, pore size of the membranes increased with increasing concentrations of SPEEK in the casting solution. Similarly, the MWCOs of the blend membranes ranged from 20 to 45 kDa, depending on the various polymer blend compositions. The pure water flux of the PSf/SPEEK blend membranes increases from 16.7 to 61.5 l m⁻² h, when the concentration of SPEEK increased from 0 to 15 wt%. Scanning electron microscope (SEM) results qualitative evidence for the trends observed for the pore statistics and MWCO studies.