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1.
Plate-like potassium magnesium titanate (KMTO) powder prepared by molten salt growth method and the KMTO porous ceramic synthesised by polymeric sponge replication method were used as sorbents to remove nickel ions from wastewater. Both powder and porous ceramic were characterised by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The maximum adsorption capacities of powder and porous ceramic were 96 and 24?mg?g??1 respectively at a pH value of 6 (25°C). However, the removal efficiencies of both could reach up to 99%. Moreover, the adsorption kinetics for the KMTO powder and the porous ceramics followed the pseudo-second-order kinetic model, and the equilibrium data for the KMTO powder fitted the Langmuir isothermal model well, while the porous ceramics fitted with the Freundlich model. The mechanism of the adsorption by the KMTO powder and the porous ceramic was ion exchange. It was also shown that the nickel saturated KMTO powder and the porous ceramics were stable in leaching tests. 相似文献
2.
Hidemitsu Aoki Kazuki Miyano Daisaku Yano Koji Yamanaka Takashi Sugino 《Electrochimica acta》2008,53(22):6657-6661
A biological and chemical sensor with rapid response at the microlevel is required for health and environmental monitoring. To develop a high-performance sensor, we use a porous monolith-type ion exchanger having three-dimensional acceptors to sense chemical substances. This porous monolith-type ion exchanger has an open-cellular structure with 5-50-μm diameter pores. The concentration of amino acids in the solution can be detected by measuring the impedance of the monolith-type ion exchanger. The novel ion exchanger has a high-exchange rate and high-electrical conductivity compared with that of the conventional ion-exchange resins. It is found that the impedance of the porous ion exchanger varies widely, depending on the amino acids such as glycine, asparatic acid, lysine, and phenylalanine. The impedance of anion exchanger had the highest value for phenylalanine with a benzene ring. OH-ion conduction is suppressed possibly due to the phenylalanine molecules stabilized by the hydrophobic interaction with the anion exchanger. In addition, we succeeded in sensing amino acid ions with concentration as low as 10−7 mol. The porous ion exchanger has the potential of a high-performance device for biological and chemical sensing. 相似文献
3.
Zongbin Wu Jingcheng Tian Zhongmin Liu Peng Tian Lei Xu Yue Yang Yangyang Zhang Xinhe Bao Xiumei Liu Xianchun Liu 《Journal of Porous Materials》2006,13(1):73-80
Neutral dibutyl methylphosphonate (DBMP) is used as a template to prepare porous metal methylphosphonates (metal = aluminum,
titanium, zirconium). The removal of DBMP in the as-synthesized materials could be easily achieved by evaporation under vacuum
without destroying the hybrid structure, as evidenced by elemental analyses, FT-IR spectra, 13C CP/MAS NMR and nitrogen adsorption-desorption isotherms. Thermal analyses show that three porous hybrid samples have high
thermal stability in air. The exothermic weight losses due to oxidation combustion of organic species occluded in samples
appear after 730 K. Furthermore, the templating effect of DBMP is also confirmed by comparing the hybrid materials synthesized
in the presence or the absence of the template. 相似文献
4.
Ann Mari Svensson 《Electrochimica acta》2005,50(13):2647-2653
Porous metal hydride electrodes of the alloy MmNi3.5-3.7Co0.7-0.8 Mn0.3-0.4Al0.3-0.4 have been characterized by means of impedance spectroscopy. A mathematical model for the impedance response, including effects of diffusion of hydrogen, surface kinetics, conductivity in the metal phase and the solution phase, as well as a continuous, lognormal, particle size distribution, was implemented and fitted to the experimental results by application of a least square fitting routine. The model is based on physical parameters, thus avoiding problems related to the conventional interpretation of impedance spectra in terms of equivalent circuits. Very good agreement between experimental results and model results was obtained for a wide range of frequencies, indicating that physical parameters to a great extent can be determined under realistic operating conditions. The latter was confirmed by independent measurements of the variation in open circuit voltage with respect to the state of charge of the electrode. The model provides an improved methodology for the determination of diffusion coefficients based on electrochemical impedance data. Furthermore, the model can be applied for parametric studies of metal hydride electrodes. 相似文献
5.
Raji Atchudan Thomas Nesakumar Jebakumar Immanuel Edison Dasagrandhi Chakradhar Namachivayam Karthik Suguna Perumal Yong Rok Lee 《Ceramics International》2018,44(3):2869-2883
Cobalt oxide nanoparticles@nitrogen-doped reduced graphene oxide (Co3O4@N-rGO) composite and nitrogen-doped graphene dots (N-GDs) were synthesized by a one-pot simple hydrothermal method. The average sizes of the synthesized bare cobalt oxide nanoparticles (Co3O4 NPs) and Co3O4 NPs in the Co3O4@N-rGO composite were around 22 and 24 nm, respectively with an interlayer distance of 0.21 nm, as calculated using the XRD patterns. The Co3O4@N-rGO electrode exhibits superior capacitive performance with a high capability of about 450 F g?1 at a current density of 1 A g?1 and has excellent cyclic stability, even after 1000 cycles of GCD at a current density of 4 A g?1. The obtained N-GDs exhibited high sensitivity and selectivity towards Fe2+ and Fe3+, the limit of detection was as low as 1.1 and 1.0 μM, respectively, representing high sensitivity to Fe2+ and Fe3+. Besides, the N-GDs was applied for bio-imaging. We found that N-GDs were suitable candidates for differential staining applications in yeast cells with good cell permeability and localization with negligible cytotoxicity. Hence, N-GDs may find dual utility as probes for the detection of cellular pools of metal ions (Fe3+/Fe2+) and also for early detection of opportunistic yeast infections in biological samples. 相似文献
6.
Arianna Gambirasi Sandro Cattarin Marco Musiani Lourdes Vázquez-Gómez Enrico Verlato 《Electrochimica acta》2011,(24):8582
A method for decorating the surface of disk electrodes with metal nanowires is presented. Cu and Ni nanowires with diameters from 1.0 μm to 0.2 μm are directly deposited on the electrode surface using a polycarbonate membrane filter template maintained in contact with the metal substrate by the soft homogeneous pressure of a sponge soaked with electrolyte. The morphologic and structural properties of the deposit are characterized by scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). The latter shows that the head of nanowires with diameter of 0.4 μm is ordinarily polycrystalline, and that of nanowires with diameter of 0.2 μm is almost always monocrystalline for Cu and frequently also for Ni. Cyclic voltammetries and impedance investigations recorded in alkaline solutions at representative Ni electrodes decorated with nanowires provide consistent values of roughness factor, in the range 20–25. 相似文献
7.
In the present work, ion exchange resin based on hydroxyethyl cellulose has been synthesized to remove the heavy metals, such as iron, cobalt, copper, and zinc from their aqueous solutions. The conditions in the column and batch modes were investigated for this purpose. The resin, having an average swelling percentage of 75.94 and an exchange capacity of 2.57 meq g−1 resin, is being introduced as a new ion exchange resin in the heavy metal removal process. An investigation of the column operations using aqueous solutions of heavy metal ions indicated that the resin prepared has some advantages, including high total exchange capacity and good chemical stability. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3501–3506, 1999 相似文献
8.
We present a study on the axial dispersion in metal foams and laser sintered reactors. Commercially available metal foams of 20 and 30 ppi are compared to a designed streamwise-periodic structure in terms of axial dispersion coefficients and pressure drops. Therefore tracer pulse experiments were performed and post processed by means of a deconvolution method. The Peclet number Pep based on the pore size is ranging from 5×104 to 8×105 which is attributed to the increased velocities due to the high porosity of the material compared to fixed bed reactors. The attained dispersion coefficients ranging from 1.3×10−4 to demonstrate the trend of packed beds and common packing materials and increase monotone with the Peclet number Pep. The pressure drop versus the interstitial bulk velocity follows the Forchheimer equation and can be described by the conventional Ergun model for all investigated porous media. The parameters obtained correspond to values found in literature. The results of this study show the high potential of foam reactors for catalyst driven reactions. They provide the same or even a higher surface area per volume of catalyst bed while inducing a much smaller pressure drop than corresponding fixed beds. 相似文献
9.
The growth of nanoporous alumina at an aluminium surface which is not completely covered by an electrolyte has been investigated. At one point the electrolyte forms three interfaces: oxide/electrolyte, metal/electrolyte, electrolyte/air. At this three-interfaces-point a self-wetting induced oxide growth occurs. The wetting increases up to 7 mm from the electrolyte contact edge. At this final stage of wetting an equilibrium between the wetting induced flow (bottom-up) and the gravity-driven flow (top-down) is reached. The thickness of the nonporous layer decreases with the distance from the starting point. 相似文献
10.
Violetta Gianneta Antonis Olziersky Androula G Nassiopoulou 《Nanoscale research letters》2013,8(1):71
Abstract
We report on Si nanopatterning through an on-chip self-assembled porous anodic alumina (PAA) masking layer using reactive ion etching based on fluorine chemistry. Three different gases/gas mixtures were investigated: pure SF6, SF6/O2, and SF6/CHF3. For the first time, a systematic investigation of the etch rate and process anisotropy was performed. It was found that in all cases, the etch rate through the PAA mask was 2 to 3 times lower than that on non-masked areas. With SF6, the etching process is, as expected, isotropic. By the addition of O2, the etch rate does not significantly change, while anisotropy is slightly improved. The lowest etch rate and the best anisotropy were obtained with the SF6/CHF3 gas mixture. The pattern of the hexagonally arranged pores of the alumina film is, in this case, perfectly transferred to the Si surface. This is possible both on large areas and on restricted pre-defined areas on the Si wafer.PACS
78.67.Rb, 81.07.-b, 61.46.-w 相似文献11.
Porous alumina films have been synthesised by anodisation of high purity aluminium in 0.4 M phosphoric acid at constant current density. The dissolution process of those coatings in 2 M phosphoric acid has been investigated by in situ spectroscopic ellipsometry (SE) combined with electrochemical measurements. A sharp drop of the open current potential is observed due to film removal. The dissolution time depends on total barrier layer thickness. Those results are confirmed by SE measurements. A three layer optical model has been used to interpret SE spectra. During the dissolution process, the porous top layer has a quasi-constant thickness, whereas porosity increases significantly. The dissolution proceeds within the pores. Only the thickness of pure alumina barrier layer (upper part) decreases during the dissolution process whereas the interface barrier layer (lower part) does not change. 相似文献
12.
13.
Surface X-ray scattering (SXS) in transmission geometry provides a valuable tool for in situ structural studies of electrochemical interfaces under reaction conditions, as illustrated here for homoepitaxial electrodeposition on Au(1 0 0) and Au(1 1 1) electrodes. Employing diffusion-limited deposition conditions to separate the effects of potential and deposition rate, a mutual interaction between the interface structure and the growth behavior is found. Time-dependent SXS measurements during Au(1 0 0) homoepitaxy show with decreasing potential transitions from step flow to layer-by-layer growth, then to multilayer growth, and finally back to layer-by-layer growth. This complex growth behavior can be explained within the framework of kinetic growth theory by the effect of potential, Cl adsorbates and the Au surface structure, specifically the presence of the surface reconstruction, on the Au surface mobility. Conversely, the electrodeposition process influences the structure of the reconstructed Au surface, as illustrated for Au(1 1 1), where a significant deposition-induced compression of the Au surface layer as compared to Au(1 1 1) surfaces under ultrahigh vacuum conditions or in Au-free electrolyte is found. This compression increases towards more negative potentials, which may be explained by a release of potential-induced surface stress. 相似文献
14.
DNA-immobilized porous polysulfone beads for organic compounds and heavy metal ion removal 总被引:4,自引:0,他引:4
Changsheng Zhao Kaiguang Yang Xiangdong Liu Motoyoshi Nomizu Norio Nish 《Desalination》2004,170(3):263-270
Sorption and pervaporation experiments were carried outwith PVA/PAA cross-linked membranes for the separation of azeotropic methyl tert-butyl ether and methanol mixtures. The influence of the PVA/PAA ratio and liquid mixture composition were investigated. With increasing PAA content in the membranes, solubilities and fluxes decreased and selectivities increased. Total sorption and fluxes increased with increasing concentration of McOH. Increasing the concentration of McOH resulted in decreasing selectivities. Because of polarity, McOH permeated selectively through the membranes. Sorption results showed the same tendency with pervaporation results. 相似文献
15.
16.
This paper studies the detection of copper ions by using an iminodiacetatic acid (IDA) modified conducting copolymer electrode. The copolymer film comprising 3-methyl thiophene (3MT) and 3-thiophene acetic acid (3TA) was chosen as the selective metal cation sensing electrode. The carboxylic group of the copolymer was modified to produce IDA group for metal ion capture. The modified electrode was used for the electrochemical analysis of trace copper ions by square wave voltammetry (SWV) technique. The electrode was found to be highly selective to Cu2+ in the range of 0.1-10 μM. The modified electrode offered an excellent way, with a high stability and reusability, for selective determination of Cu2+ in a solution of mixed metal ions. 相似文献
17.
The electrochemical oxidation of pyridoxol (PN) on a polycrystalline gold electrode was investigated by cyclic voltammetry and in situ Fourier transform infrared spectroscopy (FTIRS). In 0.1 M aqueous NaOH solution, the gold electrode showed a high catalytic activity for the irreversible oxidation process of PN. The individual ionic species and the major tautomeric equilibria of PN molecules in aqueous solutions were evidenced well from the pH-dependent attenuated total reflectance (ATR) spectra, and the results were in good agreement with the voltammetric observations. In situ single potential alteration infrared reflectance spectroscopy (SPAIRS) demonstrated that a lactone form of PN, rather than pyridoxal aldehyde, was likely formed, which was subsequently diffused into the thin layer solution and underwent hydrolysis slowly to pyridoxic acid (PA) as the final product. In addition, the adsorption of PN at Au electrode was characterized by in situ subtractively normalized interfacial Fourier transform infrared reflectance spectroscopy (SNIFTIRS) method, which revealed that the adsorption of deprotonated PN, via nitrogen atom in vertical configuration on electrode surface, occurred from −0.5 V versus Ag?AgCl?KCl(sat), which was much lower than the potential of PN electrooxidation observed from ca. 0 V. 相似文献
18.
We report on three different methods to prepare nanostructured materials using highly ordered porous alumina membranes as templates: (1) firstly, a new and simple method, termed as the paired cell method, was developed for the preparation of inorganic nanowires. Several kinds of inorganic nanowires were synthesized using this method. The structure and composition of these nanowires were determined by field emission scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy. (2) Secondly, highly ordered platinum nanowire arrays were prepared by electrochemical method with the help of porous alumina membrane templates. The structure and composition of these nanowire arrays were also characterized by various experimental techniques. The electrochemically active surface area of the nanowire arrays was determined by cyclic voltammetry based on hydrogen adsorption. Results showed that the platinum nanowire arrays exhibited a large surface area. (3) Finally, we also present a simple and reliable procedure for the preparation of highly ordered metal nanohole and nanopillar arrays, based on the anodic oxidation of aluminum and vacuum evaporation technology. The field emission scanning electron microscopic images revealed that these metal nanostructure arrays were highly ordered over a large area. The nanoimprinting of aluminum surfaces using the as-prepared chromium nanopillar arrays was demonstrated, resulting in periodic indentation on the aluminum surface. 相似文献
19.
Highly ordered porous Cu2O film is electrodeposited on copper foil through a self-assembled polystyrene sphere template. Compared with the dense Cu2O film and the octahedral Cu2O powder, the ordered porous Cu2O film exhibits an improved electrochemical cycling stability. The capacity of the porous Cu2O film can maintain 336 mAh g−1 and 213 mAh g−1 after 50 cycles at the rate of 0.1 C and 5 C, respectively. The reversible capacity holds 63.4% as the discharge-charge rate even increases by 50 times. The enhanced high rate properties of the ordered porous film should be attributed to the sufficient contact surface of Cu2O/electrolyte and the short diffusion length of Li+. Moreover, the direct contact between Cu2O and current collector and the decreasing inactive interfaces of Cu2O/polymer binder are also suggested as being responsible for the enhanced high rate property. 相似文献
20.
A nanostructured gold surface consisting of closely packed outwardly growing spikes is investigated for the electrochemical detection of dopamine and cytochrome c. A significant electrocatalytic effect for the electrooxidation of both dopamine and ascorbic acid at the nanostructured electrode was found due to the presence of surface active sites which allowed the detection of dopamine in the presence of excess ascorbic acid to be achieved by differential pulse voltammetry. By simple modification with a layer of Nafion, the enhanced electrocatalytic properties of the nanostructured surface was maintained while increasing the selectivity of dopamine detection in the presence of interfering species such as excess ascorbic and uric acids. Also, upon modification of the nanostructured surface with a monolayer of cysteine, the electrochemical response of immobilised cytochrome c in two distinct conformations was observed. This opens up the possibility of using such a nanostructured surface for the characterisation of other biomolecules and in bio-electroanalytical applications. 相似文献