Chemical and biological treatment of waste water with a novel silver/ordered mesoporous alumina nanocomposite

One of the serious problems in the present century is chemical and biological pollution of the environment. Nanocomposites are multiphase solid materials that have been used as adsorbent of pollutants such as dyes, pesticides, anions and etc. in the last decades. In this study, a novel nanocomposite including silver nanoparticles and ordered mesoporous alumina (OMA) has been synthesized and used for the removal of dyes pollutants (methyl orange, bromothymol blue and reactive yellow) from aqueous solution. The characterization of synthesized nanocomposite has been performed by TEM, N₂ adsorption/desorption, XRD and energy dispersive X-ray spectroscopy analysis. The adsorption kinetic and equilibrium data have been obtained by UV–vis spectroscopy. The results show that the silver/OMA nanocomposite (Ag/OMA nanocomposite) is good adsorbent for the removal of anionic dyes from aqueous solution, and also this nanocomposite has a biocidal action against both Gram-negative and Gram-positive bacteria.     

Sol-gel synthesis of ordered mesoporous alumina

Well-ordered mesoporous alumina materials with high surface area and a narrow pore size distribution were synthesized using a sol-gel based self assembly technique.     

Electrochemical synthesis of ordered alumina nanowire arrays

Ordered Al₂O₃ nanowire arrays embedded in the nanochannels of anodic alumina membranes (AAMs) were synthesized by electrodepostion at room temperature. Our synthetic route yielded large quantities of Al₂O₃ nanowires of uniform size and shape that are ~40 μm long with diameters of 70 nm. The Al₂O₃ nanowire structures were characterized by scanning and transmission electron microscopies, high-resolution transmission electron microscopy, energy dispersive spectroscopy and X-ray photoelectron spectroscopy. Electronic Publication     

Excitation polarization sensitivity of plasmon-mediated silver nanotriangle growth on a surface

In this contribution, we report an effective and relatively simple route to grow triangular flat-top silver nanoparticles (NPs) directly on a solid substrate from smaller NPs through a wet photochemical synthesis. The method consists of fixing small, preformed nanotriangles (NTs) on a substrate and subsequently irradiating them with light in a silver seed solution. Furthermore, the use of linearly polarized light allows for exerting control on the growth direction of the silver nanotriangles on the substrate. Evidence for the role of surface plasmon resonances in governing the growth of the NTs is obtained by employing linear polarized light. Thus, this study demonstrates that light-induced, directional synthesis of nanoparticles on solid substrates is in reach, which is of utmost importance for plasmonic applications.     

Synthesis of highly dispersed ceria-zirconia supported on ordered mesoporous alumina

Highly dispersed ceria-zirconia supported on ordered mesoporous alumina, showing higher thermal stability up to 900 °C, has been successfully synthesized via a sol-gel process associated with P123 as the template in ethanol solvent.     

Preparation of an A-type zeolite film on the surface of an alumina ceramic filter

An A-type zeolite film was prepared on the outer surface of an alumina ceramic filter by repeated hydrothermal syntheses using the same sample (referred to as repeated batch synthesis). The thickness of the film was found to increase to 35 μm by precipitating the crushed zeolite crystal on the ceramic filter and to 50 μm by precipitating the crushed alumina before repeated batch synthesis. The structure and atomic composition of the zeolite film obtained were found to the same as those of the corresponding original zeolite using several spectrometric methods: X-ray diffraction (XRD), ²⁹Si magic-angle spinning nuclear magnetic resonance (MAS NMR) and electron-probe microanalysis (EPMA). The morphology and thickness of the zeolite film were dependent on the reaction time and temperature, and especially on the types of silica and alumina sources. The preferred silica and alumina sources were Na₂SiO₃ and Al(OH)₃, respectively; these are different from the usual sources for the synthesis of powdery A-type zeolites.     

SIMS investigations on the growth mechanisms of protective chromia and alumina surface scales

The oxidation behaviour of the oxide-dispersion strengthened (ODS) high-temperature alloys MA 956 (an aluminium oxide former) and MA 754 (a chromium oxide former) has been compared with that of two model alloys, Fe-20Cr-5Al and Ni-25Cr. The morphology and composition of the oxide scales were investigated by metallography, X-ray diffraction analysis and scanning electron microscopy. For analysis of the oxide layer growth mechanisms, twostage oxidation experiments with¹⁸O as tracer were used, the distribution of the oxygen isotopes in the oxide scale being determined by SIMS. The ODS alloys show a more selective oxidation than the two model alloys; moreover, the protective oxides on the ODS alloys have a lower growth rate and better adhesion than those on the two model alloys. From the SIMS investigations it can be deduced that the improved properties of the layers on the ODS alloys result from a change in the transport processes in the protective layer; whereas the aluminium and chromium oxide films on the conventional alloys grow by cation and anion transport, the scales on the ODS alloys grow almost exclusively by anion transport. It is shown that the observed properties of the oxide scales on the ODS alloys can be explained by this change in transport mechanism.Dedicated to Professor Günther Tölg on the occasion of his 60th birthday     

Preparation of an ordered zeolite MFI film by epitaxial growth

An ordered zeolite MFI film has been prepared on the substrate of a {001} basal face of high-quality large silicalite-1 crystals by epitaxial growth.     

Orienting influence of silver crystals upon the growth of surface oxides

Conclusions The orientation of crystals of metallic silver determines the orientation of the crystals formed on the metal oxide and silver peroxide. The cause of the conservation of the orientation is the closeness of the dimensions of their planer cells. The large oxygen ions can be inserted into the surface layer of the metal as a result of the substantial decrease in the dimensions of its atoms during ionization.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 512–515, March, 1967.     

New insights on the stereodynamics of ethylene adsorption on an oxygen-precovered silver surface

The control of spatial orientation of molecules has a great influence on the stereodynamics of elementary processes occurring both in homogeneous and heterogeneous phases. Nonpolar molecules have so far escaped direct experimental investigations because of their poor sensitivity to several external constraints. Recently, it has been shown that the collisional alignment produced in supersonic expansions coupled with molecular-beam velocity selection can help solve such problems. Here we show that the sticking probability of ethylene, a nonpolar molecule prototypical of unsaturated hydrocarbons, on an O(2)-precovered Ag(001) surface is larger for molecules approaching in a helicopter-like motion than for those cartwheeling. A mechanism involving a weakly bound precursor state is suggested, with helicopter molecules having a lower chance of being scattered back into the gas phase than cartwheels when colliding with preadsorbed ethylene.     

The state of oxygen on the surface of polycrystalline silver

Data obtained using the nonempirical SCF MO LCAO method in STO-3G/3-21G basis show that to interpret the experimental adsorption heats on Al₂O₃, it is unnecessary to apply the concept of the existence of charged Al–O⁺ and Al(OH) ₂ ⁺ centers.

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3-21/-3 , Al₂O₃ AlO⁺, Al(OH) ₂ ⁺ .

     

Adsorption behavior of PS‐PEO diblock copolymers on silver and alumina surfaces: A surface plasmon resonance study

In this work, the adsorption behavior at the silver/toluene and alumina/toluene interface of polystyrene–polyethylene oxide (PS‐PEO) diblock copolymers of various molecular weights was investigated by implementation of the surface plasmon resonance (SPR) technique. This was accomplished under a careful choice of experimental setup and the use of a suitable physical model for the interpretation of the experimental data. Comparison between polystyrene homopolymer and PS‐PEO diblock copolymer adsorption measurements indicate that PS‐PEO is anchored on the alumina surface via the PEO block, while on silver the copolymer is attached by various chain segments. The measured final adsorption amounts on alumina are typical of end‐attached polymeric brush formation while the dynamics of the adsorption process present two clearly different evolution regimes. This work provides insight into the many advantages of the use of the SPR technique as a valuable tool for similar surface studies. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1580–1591, 2006     

Luminescence of ordered silver iodide nanoclusters inside zeolite host

Ordered silver iodide nanoclusters inside zeolite Y host were prepared by using a thermal diffusion method. The Y-AgI samples were characterized with powder X-ray diffraction, differential thermal analysis, X-ray photoelectron spectroscopy, adsorption technique and chemical analysis. The results show that silver iodide nanoclusters were situated in the ordered cages of the zeolite Y host. The results on the luminescence of the nanocomposites Y-AgI suggest that when the sizes of silver iodide nanoclusters are were very small, non-radiation surface recombination exceeds radiation process and the luminescence efficiency increases as the size of the silver iodide nanoclusters increaseds As the sizes of AgI nanoclusters increased, non-radiative surface recombination effect become equal to the radiation effect of the excitons. As the size of the nanoclusters of AgI in zeolite host further increases, the surface recombination of the nanoclusters becomes a major process.     

One-step synthesis of dimethyl ether from syngas on ordered mesoporous copper incorporated alumina

Ordered mesoporous copper incorporated Al_2O_3(Cu/Al_2O_3) with high Cu dispersion were prepared by a facile solution combustion synthesis method using aluminum nitrate and copper nitrate as oxidants and urea as fuel. It is a facile and green route to synthesize catalysts for dimethyl ether directly from syngas. Cu/Al_2O_3 catalysts were characterized by XRD, N_2 adsorption–desorption, SEM-EDS, and H_2-TPR.The results indicate that the catalysts obtain an ordered mesoporous structure and copper is homogenously dispersed. The mesoporous Cu/Al_2O_3 catalysts were utilized as bifunctional catalysts in syngas to dimethyl ether reaction(STD). The copper content affects the catalytic performance in STD reaction. The CO conversion and DME selectivity of Cu/Al_2O_3 with 15% copper molar ratio achieve 52.9% and 66.1%,respectively. Moreover, the mesoporous Cu/Al_2O_3 catalysts show excellent stability in STD reaction.     

Facile method for fabrication of nanocomposite films with an ordered porous surface

This paper presents a novel and facile method for the fabrication of nanocomposite films with ordered porous surface structures. In this approach, a water-borne poly(styrene-co-butyl acrylate-co-acrylic acid)/silica nanocomposite dispersion was synthesized in situ by surfactant-free emulsion polymerization by using 3-allyloxy-2-hydroxy-1-propanesulfonate as a polymerizable surfactant. When this dispersion was dried to form a film at a certain temperature, an ordered porous structure could be directly obtained on the surface of the nanocomposite film. SEM, TEM, and AFM were employed to observe the morphology, and XPS and particle analyzer were used to analyze the surface composition of the ordered porous nanocomposite film and the particle size, respectively.     

Fabrication of ordered Ni nanocones using a porous anodic alumina template

Hexagonally ordered Ni nanocones have been produced using an electroless Ni deposition technique on a porous anodic alumina (PAA) template, where the pores are of a cone shape. The conical PAA film was found to exhibit hexagonal order with a period of 100 nm. The aspect ratio (cone height vs. the diameter of the base of the cone) of the conical pores on the PAA film was found to be one. The Ni nanocones and the surface morphology of the nano-conical film exhibit the same periodic structure of the template. A significant advantage of the fabrication process employed in this work is that it utilizes existing techniques.     

氧化铝负载的银纳米颗粒高选择性催化合成亚胺(英)

The oxidative dehydrogenation of alcohols to aldehydes catalyzed by Ag nanoparticles supported on Al₂O₃ was studied.The catalyst promoted the direct formation of imines by tandem oxidative dehydrogenation and condensation of alcohols and amines.The reactions were performed under mild conditions and afforded the imines in high yield（up to 99%） without any byproducts other than H₂O.The highest activity was obtained over 5 wt%Ag/Al₂O₃ in toluene with air as oxidant.The reactions were also performed under oxidant-free conditions where the reaction was driven to the product side by the production of H₂ in the gas phase.The use of an efficient and selective Ag catalyst for the oxidative dehydrogenation of alcohol in the presence of amines gives a new green reaction protocol for imine synthesis.     

The ordered thin-film growth of organic semiconductor on Ag(110)

Growth of ordered perylene thin films on the Ag(110) surface has been investigated with scanning tunneling microscope. By saturating the surface with a monolayer of perylene molecules, two kinds of ordered structures are simultaneously formed with flat-lying perylene molecules on the Ag(110) surface, in which one is commensurate relative to the Ag substrate with a periodicity of while the other is commensurate with a periodicity of (-2724). There is one molecule within the former unit cell with a surface coverage of 0.1 molecule per Ag atom, while there are two molecules within the latter unit cell, which gives a slightly lower surface coverage of 0.091 molecule per Ag atom. Ab initio calculations have been carried out to identify the adsorption geometry and bonding sites.     

Carrol rearrangement on the surface of chromatographic grade alumina

Thermolysis on the surface of Al₂O₃ is proposed as a mild and convenient preparative method for /3,3/-sigmatropic Carrol rearrangement of acetoacetic esters of tertiary allyl alcohols into respective γ-δ-unsaturated ketones.