Processing of alumina-coated clay–diatomite composite membranes for oily wastewater treatment

Crack-free alumina-coated clay–diatomite composite membranes were successfully prepared by a simple pressing and dip-coating route using inexpensive raw materials at a temperature as low as 1000 °C in air. The changes of porosity, flexural strength, pore size, flux, and oil rejection rate of the membranes were investigated while changing the diatomite content. A simple burn-out process subjected to the used membranes in air completely recovered the specific surface area, steady state flux, and oil rejection rate of the virgin membranes. The recycled membranes showed an exceptionally high oil rejection rate (99.9%) with a feed oil concentration of 600 mg/L at an applied pressure of 101 kPa. The typical porosity, pore size, flexural strength, oil rejection rate, and steady state flux of the recycled alumina-coated clay–diatomite composite membrane were 36.5%, 0.12 μm, 32 MPa, 99.9%, and 6.91×10⁻⁶ m³ m⁻² s⁻¹, respectively, at an applied pressure of 101 kPa.     

Research progress of γ-alumina support

由于γ-Al₂O₃载体的孔结构、表面酸性等性质的可调性,γ-Al₂O₃载体被广泛应用于催化剂载体领域。催化剂的孔结构、表面性质均取决于γ-Al₂O₃载体,因此通过掌握γ-Al₂O₃载体性质的可调变规律就可制备出适合特定催化反应的高性能载体。本文以γ-Al₂O₃载体制备及γ-Al₂O₃载体后处理等过程为出发点,详细评述了近年来γ-Al₂O₃载体的孔结构、表面酸性和水热稳定性等性质调变的最新研究进展,并指明了γ-Al₂O₃载体今后研究重点和发展方向。     

Metal–support interactions on rhodium model catalysts

Metal–support interactions on supported rhodium catalysts were studied by using specially prepared Rh/TiO₂/Mo model systems. For their characterization and the analysis of modifications due to various heat treatments several surface analytical methods were applied: low-energy ion scattering, X-ray photoemission spectroscopy and thermal desorption spectroscopy. Heating in ultrahigh vacuum to 670 K leads to Rh agglomeration followed (above 720 K) by encapsulation including the formation of reduced titanium oxide species. These morphological and chemisorption changes are reversible upon reoxidation and low-temperature reduction and thus exhibit the characteristic features of strong metal–support interactions. For the effective mechanism a reaction is suggested that involves oxygen chemisorption on the Rh clusters and partial reduction of the surrounding support oxide.     

Improvement of the evaluation of inkjet printed silver based layers’ adhesion

This paper presents the improved method of analysis and evaluation of the silver layers’ adhesion printed by inkjet printing technology. The generally known method for adhesion measurement of layers and coatings according to the standards ASTM D3359 and ISO 2409 has been improved by development of the automatic evaluation software of achieved results from cross cut tests. The developed evaluation tool offers the possibilities of calculation the detached area, rotation of the image, setting the threshold and the automatic classification according to the mentioned standards. The inaccuracy caused by samples’ assessment by humans is mainly eliminated by using of this tool. The developed evaluation tool has been applied to experimental works oriented to analysis of the adhesion of two commercially available silver based nano-inks on two polymeric based substrates (PI and PET). For this purpose, different sintering conditions have been applied to analysed samples. The achieved results show the differences between the investigated nano-inks’ adhesion on two types of polymeric substrates. The adhesion of silver layers can be optimized by controlling the sintering conditions. By developing the software tool the simple and inaccurate method of adhesion analysis has been upgraded to the appropriate technique to the silver layers’ adhesion testing. The improved method for adhesion measurements can serve as a tool for fast and relatively simple technique for technologist.     

Weak boundary layers on vulcanized styrene–butadiene rubber treated with sulfuric acid

A synthetic vulcanized styrene-butadiene rubber (R2) was used in this study. The presence of paraffin wax and zinc stearate in the rubber composition prevented the adhesion of R2 rubber to solvent-based polyester-urethane adhesive. To increase the adhesion properties of R2 rubber, a surface treatment with sulfuric acid (cyclization) was applied, and the length of the immersion in sulfuric acid and the time between the immersion time and the neutralization were varied. The treated R2 rubber surfaces were characterized using ATR-IR spectroscopy, contact angle measurements (water, ethanediol), and scanning electron microscopy (SEM). The mechanical properties of the treated rubber were obtained from stress-strain experiments. The joint strength was obtained from the T-peel test on treated R2 rubber/polyurethane adhesive joints. Due to the penetration of the sulfuric acid into the R2 rubber bulk, the mechanical properties decreased. The treatment with sulfuric acid produced several chemical modifications on the rubber surface: sulfonation of the butadiene and the creation of C C and C O bonds. Furthermore, the surface treatment of the R2 rubber with sulfuric acid removes paraffin wax from the rubber surface, which had a beneficial effect on adhesion to the polyurethane adhesive. To remove the wax layer, the surface was wiped with petroleum ether solvent after treating the R2 rubber with sulfuric acid. However, in some experiments a progressive migration of wax from the R2 rubber bulk to the surface with time happened. The migration of wax was prevented by increasing the immersion time in H₂SO₄ by more than 5 min.     

A first-principles prediction of two-dimensional superconductivity in pristine B₂C single layers

Based on first-principles lattice dynamics and electron-phonon coupling calculations, B(2)C sheets are predicted to be a two-dimensional (2D) phonon-mediated superconductors with a relatively high transition temperature (T(c)). The electron-phonon coupling parameter was calculated to be 0.92 and it is mainly contributed by low frequency out-of-plane phonon modes and electronic states with a π character. When the Coulomb pseudopotential, μ*, is set to 0.10, the estimated temperature, T(c), is 19.2 K. To the best of our knowledge, B(2)C is the first pristine 2D superconductor with a T(c) higher than the boiling point of liquid helium.     

Synthesis of InSb and InxGa1−xSb thin films from electrodeposited elemental layers

The synthesis of thin films of indium and indium-gallium antimonides was performed by a method involving electrodeposition steps and thermal annealing. Successive layers of the elements were deposited in the order Sb, In and, when necessary, Ga. The binary InSb compound was obtained when annealing was performed at temperatures slightly higher than the In melting point. Ternary In_xGa_1-xSb films were also prepared by a similar method. These were found to consist of a single phase for x>>-0.91 and of two phases, one rich in In and the other in Ga, for x0.84. The cubic lattice parameter was determined for all phases and used for calculating their composition, assuming Vegard's law as valid.The paper is dedicated to Professor Dr Fritz Beck on the occasion of his 60th birthday.     

Transmission electron microscope observation of organic–inorganic hybrid thin active layers of light-emitting diodes

Low-resistivity indium tin oxide [ITO] film was successfully deposited on oxygen plasma-treated polyethylene terephthalate [PET] surfaces at room temperature. X-ray diffraction [XRD] measurements demonstrated that the film deposited on the PET surface that had not been treated with oxygen plasma had an amorphous structure. In contrast, after the low-power oxygen plasma treatment of the PET surface, the ITO film deposited on the PET surface had a poly-crystalline structure due to interactions between electric dipoles on the PET surface and electric dipoles in the ITO film. The minimum resistivity of the poly-crystalline ITO was about 3.6 times lower than that of the amorphous ITO film. In addition, we found that the resistivity of ITO film is proportional to the intensity of the (400) line in the film's XRD spectra.     

Characterization of molecular and biomolecular layers on diamond thin films by infrared reflection–absorption spectroscopy

We explore the use of single-bounce infrared reflection–absorption spectroscopy (IRRAS) to characterize molecular and biomolecular layers on doped and undoped diamond thin films on silicon substrates. Experimental measurements of thin layers of poly(methyl methacrylate) (PMMA) as a function of polarization and angle of incidence were used to characterize the intensity, frequency, and symmetry of the vibrational features. Fresnel multilayer reflectivity calculations were used to identify optimized conditions and to understand the observed trends. The measurements were then extended to characterize the nonspecific binding of fibrinogen as a model system. Finally, we present data demonstrating the ability to characterize Escherichia coli antibodies covalently linked to diamond surfaces, including changes in Amide I band due to conformational changes associated with protein denaturation. Our results show that dispersion and reflection effects under different experimental conditions lead to changes in the frequency of the PMMA CO mode and the fibrinogen Amide I band that are comparable to the changes due to different protein conformations. This has significant implications for the use of the Amide I feature to analyze the conformation of proteins on diamond thin film and highlights the utility of Fresnel modeling in the interpretation of FTIR spectra at surfaces.     

Tris(diethylamino)silane—A new precursor compound for obtaining layers of silicon carbonitride

Silicon carbonitride layers have been obtained by chemical deposition from the gas phase with thermal (LPCVD) and plasma (PECVD) activation of the gas mixture of helium with the new volatile siliconorganic compound tris(diethylamino)silane (Et ₂N)₃SiH (TDEAS) in the temperature region 373–1173 K. Thermodynamic simulation of the deposition processes from the gas mixture (TDEAS + He) in the temperature interval 300–1300 K and pressure interval P _tot⁰ from 1 × 10⁻² to 10 mm Hg has revealed the possibility of varying the equilibrium composition of the condensed phase depending on the synthesis temperature and the composition of the initial gas mixture. Physicochemical and functional properties of obtained layers were studied by complex of modern methods. It has been established that the chemical composition of the silicon carbonitride layers obtained by the PECVD method, depending on the deposition conditions, approaches that of silicon oxynitride or nitride, and the composition of those obtained by the LPCVD method approaches that of silicon carbide. The presence of nanocrystals with a phase composition close to the standard α-S_i3N₄ phase and of carbon inclusions has been found in the layers.     

Research progress of TiO2?Al2O3 composite support

TiO₂·Al₂O₃多孔复合氧化物是新型的催化剂载体材料,因其在加氢精制工艺上能够显著增加催化剂的脱硫、脱氮活性而逐渐受到重视。本文综述了国内外关于TiO₂·Al₂O₃多孔材料的制备方法,分析了制备方法对材料的比表面积、孔结构、表面酸性等载体性能影响的一般规律。通过对国内外研究者的TiO₂·Al₂O₃合成方法的综合评述,指出了有待发展提高的方向。     

TiO2–ZrO2 mixed oxide as a support for hydrotreating catalyst

Pure TiO₂, ZrO₂ and TiO₂–ZrO₂ mixed oxides are prepared by urea hydrolysis. Hydrotreating catalysts containing 12 wt% molybdenum are prepared using these oxides and characterized by BET surface area, pore volume, XRD and oxygen chemisorption. It is observed that oxides produced by the method of urea hydrolysis have higher surface area as compared to those available commercially. With increasing zirconia content in the mixed oxide, the surface area increases and a maximum value is obtained for a mixed oxide having Ti and Zr molar ratio of 65/35. XRD results indicate that mixed oxides are poorly crystalline in nature. Thiophene hydrodesulfurization, cyclohexene hydrogenation and tetrahydrofuran hydrodeoxygenation are taken as model reactions for evaluating catalytic activities. It is found that both O₂ uptake and catalytic activities increase with increasing zirconia content in mixed oxide and reach maximum values for the 12 wt% Mo/TiO₂–ZrO₂ (65/35) catalyst. With further increases in zirconia content, O₂ uptake and catalytic activities decrease and the lowest values are observed for the pure ZrO₂ supported catalyst.     

Catalyst–support interactions and their influence in water-assisted carbon nanotube carpet growth

We report results from characterization studies focused on a diverse selection of catalyst support materials in order to understand what makes a good catalyst support during carbon nanotube (CNT) carpet growth via water-assisted chemical vapor deposition. The growth and catalyst morphological changes occurring for thin Fe layers deposited on Al₂O₃, MgO, TiN, and ZrO₂ are compared. The growth behaviors of the catalyst substrates were evidently different, with Al₂O₃/Fe supporting CNT carpet growth and showing the highest activity and longest lifetime. The TiN/Fe catalyst also supported CNT carpet growth, albeit with much lower activity, shorter lifetime, and lower CNT quality while MgO/Fe and ZrO₂/Fe did not support CNT carpet growth under standard growth conditions. Studies using a combination of atomic force microscopy and X-ray photoelectron spectroscopy revealed a general correlation between the catalyst behavior (activity and lifetime) and the 3D evolution of the catalyst for active catalysts (Al₂O₃/Fe and TiN/Fe). Analysis of inactive catalysts under standard conditions (MgO/Fe and ZrO₂/Fe) raise interesting questions related to additional chemical interactions between the substrate and catalyst that could influence nucleation and CNT growth. This work provides a step toward understanding the challenges that arise in engineering efficient CNT growth processes on a desired substrate.     

One-step dip-coating of uniform γ-Al2O3 layers on cordierite honeycombs and its environmental applications

Cordierite honeycomb with high loading and uniform coating of γ-Al₂O₃ was prepared by a facile one-step dip coating strategy. The γ-Al₂O₃ obtained loading, which was as high as 30%, could be calculated according to the different weight of bare and washcoated cordierite honeycomb. SEM micrographs showed that coarser surface and round channels were formed, demonstrating complete coverage of a γ-Al₂O₃ layer on cordierite. The coating thickness was 30 µm, corresponding very well to the theoretical value, indicating a homogeneous coating of γ-Al₂O₃. Besides, no crack was observed on the surface or the corner of the channel wall. The washcoat exhibited excellent adherence with no significant weight loss after 3 h ultrasonic treatment, attributing to the “nail-like” strong interaction between the support and the washcoat. The derived PdCl₂-CuCl₂ monolith catalyst showed excellent activity and stability for CO oxidation at room temperature in microreactor. The catalyst was also effective in pilot-scale test using the diesel exhaust as feed gas, presenting a great application prospect.     

MgF2 as a non‐conventional catalytic support. Surface and structure characterization

The paper presents results of studies on the structure of MgF₂ support, performed using various experimental methods such as XRD, IR, temperature‐programmed techniques and low‐temperature nitrogen adsorption. MgF₂ is characterized by an XRD spectrum with over 40 patterns, which enabled us to follow the changes in crystallite size and internal tension caused by the thermal treatment. TPE‐H₂O and TG allowed an estimation of the surface OH groups concentration as ∼3–4 nm^-2. This revised version was published online in July 2006 with corrections to the Cover Date.     

Immobilization of serum albumin on the synthesized three layers core–shell structures of super-paramagnetic iron oxide nanoparticles

In this study, the synthesis of four layer structures coated on magnetite nanoparticles such that Fe₃O₄/SiO₂/APTES/PEG/BSA was investigated. Magnetite nanoparticles were synthesized by co-precipitating Fe²⁺ and Fe³⁺ in an ammonia solution with the average size of 25 nm. To fabricate Fe₃O₄/SiO₂ core–shells, the magnetite nanoparticles coated by silica with Stöber method. The fabricated nanoparticles were treated by 3-aminopropyl-triethoxysilane to achieve Fe₃O₄/SiO₂/APTES nanostructures. Moreover, the nanoparticles were also attached to reactive polyethylene glycol chains. Eventually, the nanoparticles activated with bovine serum albumin for bio-application. X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, UV–vis spectroscopy and vibrating sample magnetometer were used to support the characterization.     

Compressive properties of yeast cell-loaded Ca-alginate hydrogel layers: Comparison with alginate–CaCO3 microparticle composite gel structures

The mechanical strength of alginate gel layers containing varying amounts of yeast cells was assessed by static uniaxial compression tests and compared to that of gel structures filled with equivalent quantities of inert mineral microparticles. Suitable gelation conditions were first determined by compression experiments on neat gel structures: alginate concentration, 2% w/v; Ca²⁺ ion concentration of the cross-linking solution, 100 mM; gelation time, 2 h. The presence of yeast cells in alginate disks led to the weakening of the gel structures, this effect increasing with the immobilized-cell content. By contrast, calcium chloride microparticles showing granulometric characteristics similar to those of yeast cells induced gel strengthening. The storage for 3 weeks at 4 °C in phosphate-free buffer induced noticeable weakening of alginate structures, whether filled with yeasts or not. These results are discussed in light of literature data on composite materials, in particular matrix–filler interactions.     

Influence of acid–base property of support on the toluene combustion activity of palladium

Metal–support interaction in the catalytic combustion of toluene was studied, using metal oxides with different acid–base properties as supports. The combustion activity over Pd loaded on strong acidic or basic support was lower than over Pd on weak acidic or basic metal oxides. The study of Pd surface with X-ray photoelectron spectroscopy and reaction order measurement showed that the affinity for oxygen changed according to the acid–base property of support. It was considered that the combustion activity of Pd was controlled by the acid–base property of support through an electronic interaction. This revised version was published online in July 2006 with corrections to the Cover Date.