The overall objective of this research was to evaluate a Mn oxide-coated granular activated carbon (MnGAC) for the removal and recovery of metals from wastewaters. The composite adsorbent was prepared by coating M-n-oxide onto granular activated carbon. Three coating methods (adsorption, precipitation, and dry oxidation) were developed and studied in this research. The adsorbent (MnTOG) prepared by a dry oxidation method had the highest Cu(II) adsorption capacity of the three synthesis methods. In multiple adsorption/regeneration cycle tests, MnTOG had better Cu(II) removal relative to those adsorbents prepared by other methods. MnTOG had the ability to remove Cu(II) and Cd(II) to trace level (< 4 ug/L) in a column process at least through 3000 and 1400 BV, respectively. Cd(II) removal was hindered by the presence of Cu(II). However, Cu(II) removal was only slightly reduced by the presence of Cd(II). Cu(II) adsorption in batch and fixed-bed processes onto MnTOG was successfully modeled with a homogeneous surface diffusion model (HSDM). However, the HSDM could only successfully describe the adsorption of Cd(II) onto MnTOG in the batch process, but not the fixed-bed process. M-n oxide can be deposited on GAC to create a composite adsorbent with an increased Cu(II) or Cd(II) adsorption capacity. Composite adsorbent (MnGAC) has the potential to become an efficient way to remove metals from metal contaminated wastewater.

A new composite adsorbent, iron oxide coated zeolite (IOCZ), was characterized and employed for the removal of Cu(II) from aqueous solution using fixed bed column. Scanning electron microscope (SEM), FTIR, X-ray diffraction spectrum (XRD) and BET analyses were used to study the surface properties of the coated layer. The effects of various experimental conditions, such as the flow rate, initial metal concentration and bed depth, were studied. The dynamics of the adsorption process were fitted by Adams-Bohart model and Thomas model. The Thomas model was found suitable for the description of breakthrough curve at all experimental conditions, while Adams-Bohart model was only for an initial part of dynamic behavior of the IOCZ column. The bed depth service time (BDST) model was applied to pre...

Apr 26, 1984 ... bonate, barium sulfate, sodium chloride, sulfur and alu- minum oxide. Coatings ... with a water-soluble form of a polyvinyl alcohol. (PVA), the binder, and ..... A diffuse, reflective paint composition comprising a self-polymerizing ...

Periodic multilayer structures of poly(p-phenylenevinylene)s have been fabricated by a self-assembly method on quartz or indium-tin-oxide-coated glass substrates. Alternating multilayers consisting of poly(1,4-(2-(5-carboxypentyloxy)-5-methoxyphenylene)vinylene) and poly(p-phenylenevinylene) were adsorbed onto positively charged substrates. Periodic multilayers with a microdisk geometry have also been fabricated on quartz or indium-tin-oxide-coated glass substrates. Their optical properties have been studied, and a yellow electroluminescence from a light-emitting device with a microdisk geometry has been observed.

The relation between composition of the oxide phase and the electrochemical characteristics has been investigated for ruthenium-tin (Ru-Sn) oxide-coated titanium anodes prepared by a thermal decomposition method. The oxide phases of the coatings, analyzed by X-ray diffractometry, gave almost invariable rutile structures regardless of the Ru/Sn ratio. The electrochemical characteristics were measured for the anodes with various Ru/Sn ratios using a laboratory scale chlor-alkali membrane cell. The electrochemical performance of the Ru/Sn oxide-coated anodes depended intensively on the oxide composition of the coating. 6 refs., 6 figs.

Abstract Waste red mud and natural pumice/volcanic slag particles were surface modified and their selenium adsorption from waters was investigated. Acid activation/heat treatment of original red mud (ORM) particles significantly increased their micropore and external surface area and cumulative volume of pores. Iron oxide coating of pumice/slags and acid activation of ORM decreased their pHpzc values and increased surface acidity. Selenite/selenate adsorption on iron oxide surfaces and acid activated red mud (AARM) was very fast with approximately first-order adsorption kinetics. Iron oxide coating of pumice/slag and acid activation of ORM particles significantly enhanced their selenite and selenate uptakes. Maximum Se adsorption capacities as high as 6.3 (mg Se/g adsorbent) were obtained ...

A method is provided for fabrication of superconducting oxides and superconducting oxide composites and for joining superconductors to other materials. A coating of a molten alloy containing the metallic elements of the oxide is applied to a substrate surface and oxidized to form the superconducting oxide. A material can be contacted to the molten alloy which is subsequently oxidized joining the material to the resulting superconducting oxide coating. Substrates of varied composition and shape can be coated or joined by this method.

This study used iron-oxide-coated natural rock (IOCNR) an adsorbent of arsenic from real arsenic-bearing groundwater collected from the Lanyang Plain, North Eastern Taiwan. SEM and EDX were applied to characterize the as-prepared adsorbent. Batch adsorption studies were conducted at 25+/-2^oC. A 15gL^-^1 dose of adsorbent removed ~75% of the total arsenic from the real sample when the initial arsenic concentration was 40mgL^-^1 and the pH was 7.5 (reduced to 10mgL^-^1, the maximum contaminant level (MCL)). The contact time was 6h and the agitation speed 180rpm. Adsorption followed the Langmuir isotherm and the maximum adsorptive capacity of IOCNR was 0.36mgg^-^1. The dimensionless parameter (RL) and Gibbs free energy ( G^o) changes suggested that the process is favorable and spontaneous. T...

The main objective of this work was to study the effectiveness of iron oxide-coated pumice and volcanic slag particles in removing disinfection by-product (DBP) precursors from a raw drinking water source with high specific UV absorbance (SUVA(254)) value. Iron oxide coating of particles significantly increased dissolved organic carbon (DOC) uptakes and decreased DBP formation after chlorination compared to uncoated particles. pH values close to neutral levels during adsorption and chlorination provided DOC, trihalomethane and haloacetic acid reductions around 60-75% employing 6 g/L coated particle dosage. Higher degree of DOC and DBP reductions (>85%) were obtained with increasing particle dose. The uptake of bromide by iron oxide surfaces was negligible and increasing bromide concentrations (up to 550 ?g/L) did not negatively impact the DOC uptake. However, due to competition between natural organic matter (NOM) and bicarbonate for the iron oxide surfaces, increasing bicarbonate alkalinity levels reduced DOC uptakes. Overall, the results indicated that the iron oxide-coated pumice/slag particles are effective adsorbents to remove NOM and control DBP formation in waters with relatively high DOC and SUVA(254) levels. However, they may not be effective for waters with alkalinity levels above 250 mg CaCO(3)/L. PMID:20691538

The competitive interactions between organic matter compounds and mineral surfaces are poorly understood, yet these interactions may play a significant role in the stability and co-transport of mineral colloids and/or environmental contaminants. In this study, the processes of competitive adsorption, displacement, and transport of Suwannee River natural organic matter (SR-NOM) are investigated with several model organic compounds in packed beds of iron oxide-coated quartz columns. Results demonstrated that strongly-binding organic compounds are competitively adsorbed and displace those weakly-bound organic compounds along the flow path. Among the four organic compounds studied, polyacrylic acid (PAA) appeared to be the most competitive, whereas SR-NOM was more competitive than phthalic and salicylic acids. A diffuse adsorption and sharp desorption front (giving an appearance of irreversible adsorption) of the SR-NOM breakthrough curves are explained as being a result of the competitive time-dependent adsorption and displacement processes between different organic components within the SR-NOM. The stability and transport of iron oxide colloids varied as one organic component competitively displaces another. Relatively large quantities of iron oxide colloids are transported when the more strongly-binding PAA competitively displaces the weakly-binding SR-NOM or when SR-NOM competitively displaces phthalic and salicylic acids. Results of this study suggest that the chemical composition and hence the functional behavior of NOM (e.g., in stabilizing mineral colloids and in complexing contaminants) can change along its flow path as a result of the dynamic competitive interactions between heterogeneous NOM subcomponents. Further studies are needed to better define and quantify these NOM components as well as their roles in contaminant partitioning and transport. 37 refs., 10 figs.

Titania nanotubes were fabricated by anodization of titanium foil bonded to fluorine-doped tin oxide-coated glass (FTO) by an adhesion layer of low-melting-temperature metals. The bonding layer characteristics depended on pressure and ambient environment. The bonding composition is similar to lead-free solder and the addition of antimony improved wetting further. This process presents a rapid, low-cost method for obtaining high-quality, anodizable Ti foil on FTO. (author)

Some binary RuO2-SnO2 oxides coated on Ti were synthesed by the thermal decoposion method. A remarkable behaviour of pseudo-capacitance has been shown on the cyclic voltmmograms of the prepared samples. It is concluded that the poor specific capacitance has been found for both RuO2-enriched and SnO2-enriched binary oxides. The maximum specific capacitance occurs at the composition of 40 mol% SnO2 and reaches the value of 1080Fg-1 when this electrode was annealed at the temperature of 260 degrees C. The addition of Sn into the binary oxide coating can help improve the electrode capacitancee and do no harm to the electro-catalytic properties.

Ceramic coatings were fabricated on Ti6Al4V alloy surface by microarc oxidation (MAO) in Na2SiO3-(NaPO3)6-NaAlO2 solution using an AC power supply. Microstructure and phase composition of coating were characterized by SEM and XRD, respectively. The antifriction property of the coating with and without solid lubricant sliding against SAE 52100 steel ball was investigated on a pin-on-disk friction and wear tester. The results show that the microarc oxidation coating is relatively dense and uniform, mainly composed of rutile and anatase. The coating sliding against the steel has friction coefficient as low as 0.2-0.3 at an applied load of 0.5 N and sliding cycle below 2500, which is much smaller than that of uncoated Ti6Al4V against the same counterpart. The transferring of materials from the softer steel ball onto the coating surface is the main wear event, while the microarc oxidation coating is characterized by slight abrasive wear and adhesive wear. Introducing solid graphite lubricant into the porous surface of microarc oxidation coating significantly improves the long-term antifriction property (registering friction efficient of 0.15 in the long-term sliding) under a similar sliding condition. This improvement is attributed to the reduction of materials that are transferred from the softer steel ball onto the coating surface.

The extraction of uranium from seawater involves adsorption, desorption, concentration and separation, of which the adsorption stage requires most development; uranium concentration in seawater is very low, its amount handled being extremely large. The authors have developed a metal-containing hydroxide - active carbon composite adsorbent and an AO resin adsorbent for uranium extraction from seawater. The following are described: the development of inorganic adsorbents - the preparation of a metal-containing hydroxide - active carbon adsorbent, the forming of a titanium - active carbon composite adsorbent, the extraction of uranium from seawater with a composite adsorbent; the development of organic adsorbents - the preparation of AO resin and uranium adsorption; the extraction of uranium from seawater with AO resin, the preparation of fibrous and bead-fibrous AO resin. (Mori, K.).

Abstract Protein adsorption and reversible cell attachment are investigated as a function of the grafting density of poly(N-isopropyl acrylamide) (PNIPAM) brushes. Prior studies demonstrated that the thermally driven collapse of grafted PNIPAM above the lower critical solution temperature of 32 C is not required for protein adsorption. Here, the dependence of reversible, protein-mediated cell adhesion on the polymer chain density, above and below the lower critical solution temperature, is reported. Above 32 C, protein adsorption on PNIPAM brushes grafted from a non-adsorbing, oligo(ethylene oxide)-coated surface exhibits a maximum with respect to the grafting density. Few cells attach to either dilute or densely grafted PNIPAM chains, independent of whether the polymer brush collapses abo...

A series of ZnO nanograss films grown on fluorine-doped tin oxide coated glass substrates were synthesized via hydrothermal method by using polyethyleneimine (PEI) as adjusting agent. The films were characterized by field emission scanning electron microscope (FE-SEM) and X-ray diffraction (XRD). It was found that the PEI not only affected the aspect ratios of ZnO nanograss but also changed the geometrical shape of ZnO nanograss. A possible mechanism based on PEI adsorbed on the non-polar facets of ZnO that governed the growth rate of different directions were proposed to elucidate the effect of PEI on morphology of ZnO. The ZnO nanograss films were applied to dye-sensitized solar cells (DSSCs). The results showed that the photocurrent density significantly enhanced, and the power conversi...

This project was conducted to evaluate novel approaches for removing radioactive strontium (Sr) and cesium (Cs) from the tank wastes. The bulk of the Sr removal research conducted as part of this project investigated adsorption of Sr onto a novel adsorbent known as iron-oxide-coated sand. The second major focus of the work was on the removal of cesium. Since the chemistries of strontium and cesium have little commonality, different materials (namely, cesium scavengers known as hexacyanoferrates, HCFs) were employed in these tests. This study bridged several scientific areas and yielded valuable knowledge for implementing new technological processes. The applicability of the results extends beyond the highly specialized application niches investigated experimentally to other issues of potential interest for EMSP programs (e.g., separation of chromium from a variety of wastes using IOCS, separation of Cs from neutral and acidic wastes with EC-controlled HCFs).

Silicon carbide is currently used as a structural material for heat exchanger tubes and related applications because of its excellent thermal properties and oxidation resistance. Silicon carbide suffers corrosion degradation, however, in the aggressive furnace environments of industrial processes for aluminum remelting, advanced glass melting, and waste incineration. Adherent ceramic oxide coatings developed at Solar Turbines Incorporated, with the support of the Gas Research Institute, have been shown to afford corrosion protection to silicon carbide in a simulated aluminum remelt furnace environment as well as in laboratory-type corrosion testing. The coatings are also protective to silicon carbide-based ceramic matrix composites.

This article studied the effects of sintering and extrusion on the microstructures and mechanical properties of SiC particle reinforced Al-Cu alloy composite produced by powder metallurgy method. It has been shown that both extrusion and increasing sintering temperature can significantly improve the strength and plasticity of the composite. The extrusion and increase of the sintering temperature can break up the oxide coating on the matrix powder surfaces, decrease the number of pores, accelerate the elements' diffusion and increase the density and particle interfacial bonding strength, thus significantly improve the mechanical properties of the composite. The strength and hardness of the composite increase and the elongation decreases with increasing the aging time at under-aged stage, while the strength and hardness start to decrease and the elongation starts to increase with increasing the aging time at over-aged stage due to the formation and growth of the secondary strengthening precipitates in the Al-Cu matrix.

Anodic oxidation coating of aluminum impregnated with iodine compound was prepared by electrochemical method and its bactericidal activity against Escherichia coli, Staphylococcus aureus and various molds was investigated. Iodine existed as I{sub 2} in the anodic oxidation coating of aluminum and it was stipulated the iodine from iodophore having an amorphous structure. The bactericidal activity of anodic oxidation coating of aluminum impregnated with iodine compound was high against various molds and bacterial bodies, It was thought that high bactericidal activity is due to I{sub 2} eluted from anodic oxidation coating. The anodic oxidation coating is useful as a new antimicrobial. (author)

Tin oxide coated molybdenum oxide nanowires (SnO2/MoO3) are synthesized by a combination of hydrothermal and wet chemical routes. The electrochemical capacitance properties of the SnO2/MoO3 core shell composite nanowires are measured by cyclic voltammetry (CV) and galvanostatic charge-discharge method in 1M Na2SO4 aqueous solutions. The results showed that specific capacitance of SnO2/MoO3 core shell composite nanowires is 295Fg^-^1, which is much higher than the specific capacitance of pure individual MoO3 (69Fg^-^1) and SnO2 (96.6Fg^-^1). Moreover the synthesized core shell composite nanowires has also exhibited excellent long-term cycling stability (only 3% loss of its initial specific capacitance after 1000 cycles) which may lead to its multifarious usage in high-performance energy sto...

Abstract Inorganic and organic pollutants continue to pose major problems in receiving water bodies. To overcome such problems, a new composite adsorbent material combining excellent properties of activated carbon, zeolite, and low cost adsorbents, that is, limestone and rice husk ash, was fabricated. The study also determined the capability of the new composite media to remove contaminants from semiaerobic stabilized landfill leachate. The process of identifying the optimum composition of the new adsorbent was carried out using batch technique. Further, isotherm study and regeneration of the media were investigated. Results indicated that there was favorable adsorption by both Langmuir and Freundlich isotherms. However, Langmuir isotherms were slightly better fitted for ammonia, chemical ...

The objectives were (1) to identify activated pore structure and surface chemistry characteristics that assure the effective removal of trace organic contaminants from aqueous-solution, and (2) to develop a procedure to predict the adsorption capacity of activated carbons from fundamental adsorbent and adsorbate properties. A matrix of activated carbon fibers (ACFs) (with three activation levels and four surface chemistry levels) and three commercially available granular activated carbons (GACs) served as the adsorbents. BET surface area, pore size distribution, elemental composition, point of zero charge and infrared spectroscopy data were obtained to characterize the adsorbents. The adsorption of relative hydrophilic methyl tertiary-butyl ether (MTBE) and relative hydrophobic trichloroethene (TCE) were conducted in both ultrapure water and Sacramento-San Joaquin Delta water. The results showed that an effective adsorbent for the removal of micropollutants from water requires (1) a large volume of micropores with widths that are about 1.5 times larger than the kinetic diameter of the target adsorbate, (2) a micropore size distribution that extends to widths that are approximately twice the kinetic diameter of the target adsorbate to prevent pore blockage by NOM, and (3) a hydrophobic pore surface chemistry with the sum of oxygen and nitrogen contents less than 2 to 3 mmol/g. A procedure based on the Polanyi Potential Theory (PPT) was developed to predict the adsorption capacities of activated carbons from fundamental adsorbent and adsorbate properties. A correlation between the coalescing factor for water adsorption and adsorbent oxygen content was developed. Based on this correlation, the PPT yielded reasonable estimates of aqueous phase adsorption capacities for both relatively polar and non-polar adsorbates on both relatively hydrophobic and hydrophilic activated carbons. With the developed procedure, the adsorption capacities of organic compounds that are partially miscible in water can be predicted from (1) N2 and CO2 adsorption isotherms of a given adsorbent, (2) the adsorbent oxygen content, and (3) the molar volume and parachor of the target adsorbate.

An absorbent composition containing sugar, vinegar, and diatomaceous earth is disclosed. The sugar, vinegar, and diatomaceous earth are preferably added together in about equal amounts by volume or in amounts of about 20 pounds of sugar, 2 gallons of vinegar, and 100 pounds of diatomaceous earth. The adsorbent composition has particular use in adsorbing petroleum from soil, water, or air and in water purification. (author)

A composition is proposed for reinforcing the near-face bed zone based on an epoxy compound containing epoxy resin, gasoline, polyethylene polyamine and filler, a granulated adsorbant. It is distinguished by the fact that in order to improve the strength of the composition while preserving its permeability under bed conditions, the granulated adsorbant used is granulated faience or zeolite with the following ratio of components (percent by weight): epoxy compound 19-23, granulated adsorbant 77-81, and the epoxy compound contain ethylhydrosiloxane polymer with the following ratio of components (percent by weight): epoxy resin 68-72, gasoline 20-22, polyethylene polyamine 7-8, ethylhydrosiloxane polymer 1-2.

The authors report a field emitter structure based on oxide coated carbon nanotubes (CNTs). This emitter consists of a thin tungsten ribbon with CNTs on the surface and a thin layer of low work function barium strontium oxide coating on the CNTs. This oxide coated CNT emitter was designed to combine the benefits of the high field enhancement factor from CNTs and the low work function from the emissive oxide coating. The field emission properties of the emitters were characterized. A field enhancement factor of 467 and a work function of 1.9 eV were obtained for the oxide coated CNTs. Compared to the uncoated CNTs, the field emission from the oxide coated CNTs increased by a factor of 2-3. At 4.4 V/?m, the field emission current of 23.6 ?A was obtained from an emitting surface of 0.012 cm2.

The miscibility of dodecyltrimethylammonium chloride (DTAC) and dodecylammonium chloride (DAC) in the adsorbed film at water/air interface and in the micelle was investigated by measuring the surface tension of the aqueous solution of surfactant mixture as a function of the total molality and composition of surfactants. The compositions of surfactants in the adsorbed film and micelle were evaluated by use of the thermodynamic equations developed previously. The results indicated that DTAC and DAC molecules mix slightly nonideally in the adsorbed film and micelle. Furthermore, the composition of DAC in the micelle was found to be remarkably smaller than that in the adsorbed film at the critical micelle concentration. It was concluded that the bigger hydrophilic group of DTAC is geometrically favorable for the micelle formation.   

A study was conducted on the adsorption characteristics of the adsorption refrigeration working pairs using alkaline-earth metal chlorides as adsorbents and ammonia as refrigerant. The adsorption isotherms between alkaline-earth metal chlorides and nitrogen were studied. The study shows that the adsorbents of CaCl{sub 2}, SrCl{sub 2} provide better adsorption capability associated with ammonia when compared to that of MgCl{sub 2}, BaCl{sub 2}. CaSO{sub 4} was added into the CaCl{sub 2}, SrCl{sub 2} with a mass ratio 20%, respectively, in order to solve the swelling and smashing problems encountered with CaCl{sub 2}, SrCl{sub 2} adsorbent particles. The adsorption refrigeration experiments of composite adsorbents were investigated. The results show that the refrigeration capacity of the unit adsorbent of CaCl{sub 2}/CaSO{sub 4} is 1.26 times higher than that of CaCl{sub 2}, and SrCl{sub 2}/CaSO{sub 4} is 1.6 times higher than that of SrCl{sub 2} at 100 C. The mechanism of NH{sub 3} adsorption and the gelatification of CaSO{sub 4} were also discussed. BET (Brunauer-Emmett-Teller) specific surface area and pore structure of adsorbents were examined. Results show that the BET specific surface area and pore structure of composite adsorbents are retained well. This study indicates that the refrigeration capacity could be enhanced by compositing the adsorbents which indicates that composite adsorbents can perform better in adsorption refrigeration, and can be employed in adsorption refrigeration system using low-grade heat source. (author)

This paper introduces PS300, a plasma sprayed, self-lubricating composite coating for use in sliding contacts at temperatures to 800{degrees}C. PS300 is a metal bonded chrome oxide coating with silver and BaF{sub 2}/CaF{sub 2} eutectic solid lubricant additives. PS300 is similar to PS200, a chromium carbide based coating; which is currently being investigated for a variety of tribological applications. In pin-on-disk testing up to 650{degrees}C, PS300 exhibited comparable friction and wear properties to PS200. The PS300 matrix, which is predominantly chromium oxide rather than chromium carbide, does not require diamond grinding and polishes readily with silicon carbide abrasives greatly reducing manufacturing costs compared to PS200. It is anticipated that PS300 has potential for sliding bearing and seal applications in both aerospace and general industry.

Undoped and Fe doped CdSe thin films have been deposited onto the amorphous and fluorine doped tin oxide coated glass substrates by spray pyrolysis. The Fe doping concentration has been optimized by photoelectrochemical (PEC) characterization technique. The structural, surface morphological, compositional, optical and electrical properties of undoped and Fe doped CdSe thin films have been studied. X-ray diffraction study reveals that the as deposited CdSe films possess hexagonal crystal structure with preferential orientation along (100) plane. AFM analysis shows uniform deposition of the film over the entire substrate surface with minimum surface roughness of 7.90nm. Direct allowed type of transition with band gap decreasing from 1.74 to 1.65eV with Fe doping has been observed. The activa...

Cadmium sulfide-zinc oxide composite nanorods having at least 100nm diameters were synthesized by a two-step chemical deposition technique. Polycrystalline nanorods of ZnO were grown on indium tin oxide coated quartz substrate by aqueous chemical growth technique. Cadmium sulfide was deposited on the surface of the ZnO nanorod thin film by chemical bath deposition. The X-ray diffraction results revealed the co-existence of polycrystalline CdS and ZnO, both having hexagonal structures. Neither any phase mixing nor any surface diffusion induced alloying was observed. Micro-Raman study detected a pair of optical phonons at 301cm^-^1 and 438cm^-^1 corresponding to hexagonal CdS and ZnO, respectively. An enhanced light to electricity conversion efficiency of 2.52% was recorded from CdS-ZnO phot...

Electrically conductive metal-oxide (ceramic) coatings produced by reactive ion plating are being investigated at USA-CERL for potential application in cathodic-protection systems. Ceramic materials are advantageous because of their low dissolution rates (typically less than 1 g/A/yr in 3.5% NaCl solution) and ease of fabrication. Among the ceramic anode materials currently under investigation are two systems: (1) a mixture of titanium oxide and ruthenium oxide and (2) a mixture of titanium oxides doped with niobium, each ion plated on niobium substrates. The mixed-oxide coatings were fabricated by a reactive-ion-plating process involving oxygen and dual electron-beam evaporation sources. An enhanced plasma was used to increase reactivity. X-ray diffraction, scanning electron microscopy, and energy-dispersive x-ray spectroscopy were used for characterization of the microstructure, crystallography, and elemental composition of the coating.

This paper introduces PS300, a plasma sprayed, self-lubricating composite coating for use in sliding contacts at temperatures to 800 C. PS300 is a metal bonded chrome oxide coating with silver and BaF{sub 2}/CaF{sub 2} eutectic solid lubricant additives. PS300 is similar to PS200, a chromium carbide based coating; which is currently being investigated for a variety of tribological applications. In pin-on-disk testing up to 650 C, PS300 exhibited comparable friction and wear properties to PS200. The PS300 matrix, which is predominantly chromium oxide rather than chromium carbide, does not require diamond grinding and polishes readily with silicon carbide abrasives greatly reducing manufacturing costs compared to PS200.

Indium sulphide (In{sub 2}S{sub 3}) thin films have been successfully deposited on different substrates under varying deposition conditions using chemical bath deposition technique. The deposition mechanism of In{sub 2}S{sub 3} thin films from thioacetamide deposition bath has been proposed. Films have been characterized with respect to their crystalline structure, composition, optical and electrical properties by means of X-ray diffraction, TEM, EDAX, optical absorption, TRMC (time resolved microwave conductivity) and RBS. Films on glass substrates were amorphous and on FTO (flourine doped tin oxide coated) glass substrates were polycrystalline (element of phase). The optical band gap of In{sub 2}S{sub 3} thin film was estimated to be 2.75 eV. The as-deposited films were photoactive as evidenced by TRMC studies. The presence of oxygen in the film was detected by RBS analysis. (orig.) 27 refs.

In this study, tungsten oxide coatings with 13 and 75at% of oxygen were prepared by DC reactive magnetron sputtering from a pure W target in an Ar+O2 atmosphere. The coating hardness (H) decreased with increasing oxygen content from 25 to 7.7GPa. The values of H/E ratio were 0.08 and 0.07 for W87O13 and W25O75, respectively.The tribological measurements were carried out on a pin-on-disc tribometer at room temperature, with a load of 5N and steel 100Cr6, ceramic Si3N4 and Al2O3 balls as sliding partners. The wear track and wear debris were visualised by scanning electron microscopy and the chemical composition of the later was estimated by energy-dispersive X-ray analysis. The friction coefficient was rather high in case of the W87O13 coating reaching values in the range from 0.7 to 0.75 fo...

Antimony selenide thin films have been prepared onto tin oxide coated glass substrates by potentiostatic electrodeposition from an aqueous acid bath containing K(SbO)C4H4O6s0.5H2O and H2SeO3 at 25degreeC. The electrodeposition mechanism was investigated by cyclic voltammetry. The compositional, morphological, structural, optical, and electrical properties of the deposited films have been studied using energy-dispersive X-ray spectroscopy (EDS), environmental scanning electron microscopy (ESEM), Raman spectroscopy (RS), UV-VIS spectra, and photoelectrochemical tests (PEC), respectively. The formation of antimony selenide was confirmed to proceed via an induced codeposition mechanism: Se deposition occurs first, inducing the deposition of Sb, then, the deposited Sb would further promote the ...

New compositions of titanium alloys with low Young's modulus as well as multiple surface biofunctionalities are under intense research focus for biomedical applications due to the proven ability of titanium for enhancing implant integration. This study presents the effect of plasma electrolytic oxidation coating on the fatigue response of a novel b-Ti35Zr10Nb alloy tested under physiological conditions (Hanks' solution at 37^oC). The electrolytic oxidation was conducted in calcium acetate/calcium glycerophosphate electrolyte that allowed incorporation of Ca and P within the oxide layer with potential benefits for bone apposition. The fatigue results revealed that the presence of oxide layers decreased significantly the fatigue strength of Ti35Zr10Nb alloy relative to uncoated condition. Th...

Molecular dynamics simulations of multilayer adsorption of binary mixtures of two tetrasubstituted halomethanes (CF(4) and CF(3)Br) on two very different substrates (graphite vs hydroxylated SiO(2)) were performed for three different bulk compositions (40%, 50%, and 60% CF(4)) and over a range of temperatures from 80 to 200 K. The goal of these simulations was to investigate in depth how these factors affect film structure, layer composition, lateral arrangement, and molecular orientation in the first adsorbed layer on each substrate. In line with a previous study of single-component adsorption on these surfaces, mixtures adsorbed on the hydroxylated SiO(2) surface show stable number density profiles that are largely independent of temperature, up to 160 K. This level of stability is essentially absent in the case of adsorption on graphite, which show densities and surface populations that are largely dependent on overall film composition, molecular orientation, and adsorbate-substrate interactions, in addition to system temperature. Further, the composition of the first adsorbed layer at each solid surface appears to be influenced by the choice of substrate, with CF(3)Br the majority component at the graphite surface for all compositions and temperatures, while the first adsorbed layer on hydroxylated SiO(2) more clearly mirrors the overall film composition at temperatures below 160 K. PMID:21954920

Recent observations that subsurface bacteria quickly adsorb metal contaminants raise concerns that they may enhance metal transport, given the high mobility of bacteria themselves. However, metal adsorption to bacteria is also reversible, suggesting that mobility within porous medium will depend on the interplay between adsorption-desorption kinetics and thermodynamic driving forces for adsorption. Till now there has been no systematic investigation of these important interactions. This study investigates the thermodynamic and kinetic controls of co-transport of Pantoea agglomerans cells and Zn in quartz and iron-oxide coated sand (IOCS) packed columns. Batch kinetic studies show that significant Zn sorption on IOCS takes place within two hours. Adsorption onto P. agglomerans surfaces reaches equilibrium within 30 minutes. Experiments in flow through quartz sand systems demonstrate that bacteria have negligible effect on zinc mobility, regardless of ionic strength and pH conditions. Zinc transport exhibits significant retardation in IOCS columns at high pH in the absence of cells. Yet, when mobile bacteria (non attached) are passed through simultaneously with zinc, no facilitated transport is observed. Adsorption onto cells becomes significant and plays a role in mobile metal speciation only once the IOCS is saturated with zinc. This suggests that IOCS exhibits stronger affinity for Zn than cell surfaces. However, when bacteria and Zn are pre-associated on entering the column, zinc transport is initially facilitated. Subsequently, zinc partly desorbs from the cells and redistributes onto the IOCS as a result of the higher thermodynamic affinity for IOCS. PMID:23153272

Simple wet chemical synthesis of ZnO thin films has been carried out at room temperature (27 deg. C) from an aqueous alkaline bath followed by annealing in air at 100 deg. C on fluorine doped tin oxide coated glass substrates. The deposited film showed an optical band gap of 3.28 eV with a thickness of about 40 mum with a hexagonal crystal structure. A flower-like surface morphology consisting of petals was observed. These petals are made up of a fibrous network with interconnected nanoparticles leading to a high surface area. This obliged us to use this structure for dye-sensitized solar cells with lower fabrication process cost than conventional high temperature sintered methods which are commonly used for ZnO and TiO{sub 2}. It would be advantageous to use a flexible plastic substrate instead of routine glass in future. ZnO showed a current conversion efficiency (eta) of 0.34% with chemically adsorbed N3 dye at standard AM 1.5 condition with illumination of light intensity 100 mW cm{sup -2}.

Solidification/stabilization (S/S) of hazardous iron oxide coated cement (IOCC) spent adsorbent containing arsenic (As(III)) was investigated in the present study. Cement and lime-based S/S effectiveness was evaluated by performing semi-dynamic leach tests. The S/S effectiveness was evaluated by measuring effective diffusion coefficients (D(e)) and leachability indices (LX). It was found that though cement or lime alone were efficient in preventing arsenic leaching (D(e) being in range of 10(-10) to 10(-12) for all the matrices) from the solidified matrices, the best combination for arsenic containment in the matrix was obtained when a mixture of cement and lime was used. The LX values for all the matrices were higher than 10, suggesting that the S/S treated arsenic sludge are acceptable for "controlled utilization". Calcite formation along with precipitation and conversion into non-soluble forms (calcium arsenite, calcium hydrogen arsenate hydrates, calcium hydrogen arsenates, etc.) were found to be the responsible mechanism for low leaching of arsenic from the solidified/stabilized samples. A linear relationship between cumulative fraction (CFR) of arsenic leached and square root of leach time (R(2) ranging from 0.90 to 0.94) suggested that the diffusion is the responsible mechanism for arsenic leaching. Thus, cement and lime show effective containment of the As(III) within the matrix thus indicating S/S by cement and lime, which is also a low-cost option, as a suitable management option for the toxic As(III) sludge. PMID:17913352

The performance of an adsorptive air-conditioning cycle driven by low temperature heat (80–85°C) was studied. The analysis rested on the Polanyi potential theory and took into account literature and author’s experimental data on sorption equilibrium of various conventional and innovative adsorbents with water and methanol as working fluids. This adsorbent screening is aimed at evaluating the optimal working pairs for this application. The composite sorbent of methanol Lithium Chloride in mesoporous silica gel and the adsorbent of water FAM-Z02 were selected as challenging pairs for severe conditions of heat rejection typical for solar cooling in hot countries and air conditioning in cars.   

World-wide efforts to use solid-vapour adsorption technology for heat pumps have been intensified since the imposition of international restrictions on production and use of chlorofluorocarbons. Yet, to this date solid-vapour refrigeration and heat pump systems are still under laboratory testing stages. Promising recent developments in Japan, Europe and the U.S.A. include the use of porous metal hydrides and composite adsorbents. A review of adsorbents and adsorbates used in various investigations on solid-vapour adsorption heat pumps are presented in this paper, with an aim of initiating a novel concept experimental investigation. (author)

The influence of atoms, molecules, or layers adsorbed on the cathode surface on the initiation of high-voltage gas discharge is considered. It is shown that the presence of island films of an adsorbate leads to an increase in the field-induced electron emission current that initiates breakdown of the gas-filled interelectrode gap. The formation of a continuous adsorbed film on the cathode accounts for the subsequent weak dependence of the emission characteristics in high-voltage (in particular, picosecond pulsed) discharge on the gas phase composition.

A method to control nitrogen oxide (NO{sub x}) emissions from combustion sources by adsorption of NO{sub 2} and NO on {gamma}-alumina before and after KOH treatments has been evaluated. Compared to previously studied sorbents consisting of magnesium-oxide-coated vermiculite, untreated {gamma}-alumina exhibits a 6-fold increase in activity in tubular flow system tests. XPS analyses of the adsorbent surfaces before and after exposure to NO{sub x} indicate that potassium influences the NO{sub x}-sorption process. Subsequent treatment of {gamma}-alumina with KOH by impregnation or precipitation improves the adsorptive properties of {gamma}-alumina toward both NO{sub 2} and NO, with the precipitated samples performing better than impregnated samples. This research confirms previous findings that sorption of 3 mol of NO{sub 2} on {gamma}-alumina results in the catalytic formation of 1 mol of NO. However, treatment with KOH delays and reduces the formation of NO while increasing 5-fold the amount of NO{sub 2} adsorbed. Formation of nitrate and nitrite species is observed by XPS analysis of KOH-precipitated {gamma}-alumina exposed to NO{sub x}. A 40% loss of BET surface area occurs due to KOH precipitation on {gamma}-alumina followed by a further 56% loss in surface area after saturation with NO{sub x}. The addition of water vapor (3 vol %) to the feed gas stream significantly enhances the adsorption properties of the KOH-treated {gamma}-alumina. Washing the {gamma}-alumina pellets exposed to NO{sub x} with water essentially removes all of the potassium nitrates and nitrites formed. This harmless solution can be disposed of safely or used as fertilizer, and the pellets can be regenerated.

A combination of plasma electrolytic oxidation (PEO) and impregnation techniques followed by annealing in air has been used to obtain composites Pt/nZrO2+pTiO2/Ti, Pt/nZrO2+pTiO2+zCeOx/Ti, NiO+CuO/nZrO2+pTiO2/Ti, NiO+CuO/nZrO2+pTiO2+zCeOx/Ti with different zirconium and titanium contents and ZrO2/TiO2 phase ratio. The composites have been investigated by means of XRD, XPS and SEM/XSA methods. According to the XPS data, the platinum content on the coating surface is ~0.4at.%, whereas the XSA measurements have shown that the nickel and copper contents in coatings attain 16 and 8at.%, respectively, depending on the initial oxide coatings composition. Nickel and copper oxides form either extended islets or solid layers (''crusts'') on the coating surface. Both the composites promoted with plat...

A novel boron adsorbent was fabricated by grafting a boric acid chelating group, i.e., N-methyl-d-glucamine, onto the hydrophilic silica-polyallylamine composites (SPC). The boron adsorbent was characterized by scanning electron microscopy (SEM) and TGA method. The adsorption experiment indicated a maximum boron load capacity of ca. 1.55mmolg-1. The high load capacity was attributed to specific chemical affinity and physical adsorption. Highly effective removal of boric acid from aqueous solution was observed for the adsorbent even in the synthetic seawater containing high concentration of foreign ions. Analysis of adsorption thermodynamic and kinetics revealed a spontaneous sorption process that is driven by enthalpy change and limited by chemical reaction. The exhausted adsorbent was reg...

The knowledge of multicomponent adsorption equilibria is of great importance for the industrial design and application of adsorptive purification and separation process. As the experimental determination of the required data is time-consuming and costly, theoretical help is desirable. This contribution presents and assesses the most common theoretical approaches to the calculation of multicomponent adsorption equilibria. The models are based on the assumption of an adsorbed solution, extension of the volume filling of micropores theory or statistical thermodynamics. These models are applied to different adsorptive/adsorbent systems with ideal and non-ideal equilibrium behaviour. It is established that, at low coverages of adsorbent surfaces, all theories provide good estimates of the adsorbed phase composition and total loading while, at high saturation, no model is completely satisfactory. (orig.).

The recovery of carotene from extracted oil of palm oil mill effluent (POME) was optimized by the simultaneous maximization of the carotene recovery in hexane fraction, carotene concentration and oil recovery. A central composite design consisting of 20 runs was then applied to study the factors of temperature, solvent amount and oil:adsorbent ratio. A second-order polynomial model was used to describe the experimental data regarding the responses. The main factors, solvent amount and oil:adsorbent ratio were the significant model terms for carotene and oil recoveries whereas oil:adsorbent ratio was the significant model term for carotene concentration. The optimum conditions for carotene recovery were predicted to be 40^oC, 200mL solvent and 1:4.36 of oil to adsorbent ratio and the corres...

Zeolite and activated carbon have been generally used for the adsorption separation process. Zeolite is known as polar adsorbent and activated carbon as non-polar adsorbent. A zeolite/carbon composite adsorbent from the combination of zeolite and activated carbon that consists of hydrophilic and lipophilic fractions was developed and investigated. A surfactant was used as a carbon source, and a functional group of activated carbon is deposited on the surface of zeolite. The effects of the surfactant concentration, carbonization temperature, and carbonization time on adsorption capacity were examined. The optimum condition was found to be a carbonization time of 90 min, a carbonization temperature of 750°C, and a surfactant concentration of 0.07 mol/l. The breakthrough time for H2S of the developed adsorbent was 20.5 min, 4.5 times higher than that of raw zeolite (4.4 min).   

We developed a spongiform adsorbent that contains Prussian blue, which showed a high capacity for eliminating cesium. An in situ synthesizing approach was used to synthesize Prussian blue inside diatomite cavities. Highly dispersed carbon nanotubes (CNTs) were used to form CNT networks that coated the diatomite to seal in the Prussian blue particles. These ternary (CNT/diatomite/Prussian-blue) composites were mixed with polyurethane (PU) prepolymers to produce a quaternary (PU/CNT/diatomite/Prussian-blue), spongiform adsorbent with an in situ foaming procedure. Prussian blue was permanently immobilized in the cell walls of the spongiform matrix and preferentially adsorbed cesium with a theoretical capacity of 167 mg/g cesium. Cesium was absorbed primarily by an ion-exchange mechanism, and the absorption was accomplished by self-uptake of radioactive water by the quaternary spongiform adsorbent. PMID:22464752

The chemical states of iodine trapped in Ag-Silicagel(Ag-impregnated silicagel) adsorbent during the dissolution of spent nuclear fuel have been investigated experimentally. The chemical composition of the adsorbents containing the volatile iodine trapped from a simulated spent fuel(SIMFUEL) and real spent PWR fuel was determined by EPMA(electron probe microanalysis) in the form of Ag-Silicagel beds and glass wool filter. The determination of the amount of iodine in the adsorbent samples mixed homogeneously was carried out by instrumental neutron activation analysis(INAA). The samples in polyethylene or polypropylene vials were irradiated in the pneumatic tube irradiation facilities at the HANARO reactor and then measured I-128 produced by the neutron capture reaction. This results shows that the methods can be successfully applied to know the distribution of iodine trapped in the adsorbents and in the determination of trace amount of iodine in the samples without any chemical separation.

Nuclear fuel fabrication processes produce radioactive waste solutions containing uranium which must be treated to disposal, thereby the volume of the wastes needed to be minimized. Mitsubishi Fuel Materials Co. recently developed a radioactive waste treatment method using tannin-containing adsorbents which does not produce secondary wastes. The water insoluble adsorbent (commercially available as the name 'tannix') is made of either tannic acid fixed on cellulose or poly-amino-styrene or tannic acid polymerized to gel by aldehyde. This adsorbent has a good adsorbing properties to actinides as U, Pu, and Am and the composition is solely carbon, hydrogen, and oxygen that will give on combustion only water and carbon dioxide. Adsorption characteristics, process flow, and pH dependence are explained. (S. Ohno)

Coatings and joining materials for SiC and SiC-based composites for nuclear energy systems are being developed using preceramic polymers filled with reactive and inert powders, and using solid-state reactions. Polymer-filled joints and coatings start with a poly(hydridomethylsiloxane) precursor, such that mixtures of Al/Al2O3/polymer form a hard oxide coating, coatings made with Al/SiC mixtures form a mixed oxide-carbide coating, while coatings made with SiC/polymer form a porous, hard carbide coating. Joints made from such mixtures have shear strengths range from 15 to 50 MPa depending on the applied pressure and joint composition. The strongest joints were obtained using tape cast ribbons of Si/TiC powders such that a solid state displacement reaction at 1473K using 30 MPa applied pressure resulted in shear strengths of 50 MPa, which exceeds the shear strength of SiC/SiC composite materials. However, the polymer joints are much easier to apply and could be considered for field repair.

Abstract A composite material based on lignocellulose and montmorillonite clay (MPSgLig-NaMMT) was prepared and evaluated as an adsorbent for the removal of pollutants (dyes and heavy metals) from aqueous solution. The lignocellulose-montmorillonite composite was prepared by in situ intercalative polymerisation, using methacryloxypropyl trimethoxysilane (MPS) as a coupling agent. The composite material was characterised by FTIR, TGA and SAXS. The lignocellulose-montmorillonite composite was assessed as an adsorbent for methyl orange dye from aqueous solution. The composite material showed enhanced adsorption of methyl orange (MetO) compared with the NaMMT or lignocellulose separately. Competitive adsorption studies were carried out from binary mixtures of MetO with Cd2+ or Pb2+ in aqueous ...

Desulfurization adsorbents were prepared from the mixtures of various compositions of New York City sewage sludge and fly ashes from SASOL, South Africa, by pyrolysis at 950degreeC. The resulting materials were used as adsorbents of hydrogen sulfide from simulated dry digester gas mixture or moist air. The adsorbents before and after H2S removal were characterized using adsorption of nitrogen, elemental analysis, pH measurements, XRF, XRD, and thermal analysis. It was found that the addition of fly ash decreases the desulfurization capacity in comparison with the sewage sludge-based materials. The extent of this decrease depends on the type of ash, its content and the composition of challenging gas. Although the presence of CO2 deactivates some adsorption sites to various degrees depending...

We demonstrated the replacement of the Pt catalyst normally used in the counter electrode of a dye-sensitized solar cell (DSSC) by a nanocomposite of dry spun carbon multi-walled nanotube (MWNT) sheets with graphene flakes (Gr-F). The effectiveness of this counter electrode on the reduction of the triiodide in the iodide/triiodide redox (I-/I3-) redox reaction was studied in parallel with the use of the dry spun carbon MWNT sheets alone and graphene flakes used independent of each other. This nanocomposite deposited onto fluorinated tin-oxide-coated glass showed improved catalytic behavior and power conversion efficiency (7.55%) beyond the use of the MWNTs alone (6.62%) or graphene alone (4.65%) for the triiodide reduction reaction in DSSC. We also compare the use of the carbon MWNT/Gr-F composite counter electrode with a DSSC using the standard Pt counter electrode (8.8%). The details of increased performance of graphene/MWNT composite electrodes as studied are discussed in terms of increased catalytic activity permitted by sharp atomic edges that arise from the structure of graphene flakes or the defect sites in the carbon MWNT and increased electrical conductivity between the carbon MWNT bundles by the graphene flakes.

Oxides having magnetoplumbite structure are promising candidate materials for applications as high temperature thermal barrier coatings because of their high thermal stability, high thermal expansion, and low thermal conductivity. In this study, powders of LaMgAl11O19, GdMgAl11O19, SmMgAl11O19, and Gd0.7Yb0.3MgAl11O19 magnetoplumbite oxides were synthesized by citric acid sol-gel method and hot pressed into disk specimens. The thermal expansion coefficients (CTE) of these oxide materials were measured from room temperature to 1500 C. The average CTE value was found to be approx.9.6x10(exp -6)/C. Thermal conductivity of these magnetoplumbite-based oxide materials was also evaluated using steady-state laser heat flux test method. The effects of doping on thermal properties were also examined. Thermal conductivity of the doped Gd0.7Yb0.3MgAl11O19 composition was found to be lower than that of the undoped GdMgAl11O19. In contrast, thermal expansion coefficient was found to be independent of the oxide composition and appears to be controlled by the magnetoplumbite crystal structure. Thermal conductivity testing of LaMgAl11O19 and LaMnAl11O19 magnetoplumbite oxide coatings plasma sprayed on NiCrAlY/Rene N5 superalloy substrates indicated resistance of these coatings to sintering even at temperatures as high as 1600 C.

Cationic cross-linked starch (CCS)-iodine complexes containing different amounts of quaternary ammonium groups (different degrees of substitution (DS)) and iodine have been obtained by iodine adsorption on CCS from aqueous iodine potassium iodide solution. Equilibrium adsorption studies showed that with an increase of DS the amount of iodine adsorbed on CCS and the affinity of iodine to CCS increased linearly. The influences of the DS of CCS and the amount of adsorbed iodine on the stability of CCS-iodine complexes in a solution of 0.02M sodium acetate and reactivity toward l-tyrosine have been investigated. At the same DS, the stability of CCS-iodine complexes decreased with an increase of the amount of adsorbed iodine. With increasing the DS, the stability of CCS-iodine complexes increased. The iodine consumption in the reaction with l-tyrosine increased significantly with an increase of the amount of adsorbed iodine. The influence of DS on iodine consumption was lower and depended on the amount of adsorbed iodine. The antibacterial activity of CCS-iodine complexes against Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli was determined by the broth-dilution and spread-plate methods. The obtained results have demonstrated that an appropriate selection of the CCS-iodine complex composition (the DS of CCS and the amount of adsorbed iodine) could ensure good antimicrobial properties by keeping a low concentration of free iodine in the system. The main advantage of using CCS-iodine complexes as antimicrobial agents is the biodegradability of the polymeric matrix. PMID:22885019

Although Fe oxides (includes oxide, hydroxide, and oxyhydroxide Fe minerals) are recognized as effective adsorbents for heavy metals, oxide adsorbent-based treatment processes have been limited by their small particle size. When present as a discrete mineral phase in waste streams, Fe oxide particles are typically in a colloidal size range that is difficult to remove from aqueous solution. To overcome this limitation, some possible alternatives were described which used sand or activated carbon as the supporting medium for iron oxide precipitates, or cemented iron oxide with a proprietary binding material. These adsorbents can solve the particle size problem associated with iron oxide for use in a column process with promising abilities for both cationic and anionic metals removal and recovery. Because the capacity of these adsorbents for metals depends on the amount of iron oxide on the adsorbent surface, activated carbon would seem to have an advantage as a substrate because of its large surface area. Therefore, the authors present some results of their work with a composite adsorbent made from Fe oxide and granular activated carbon. A major objective of this work was to select an appropriate equilibrium model to describe the adsorption isotherm, and to show how a first or second order reaction or homogeneous surface diffusion models could be used to model the adsorption process in the batch system.

The CdS nanoparticles capped with 2,2?-bipyridine (bpy) had been synthesized in AOT reverse micelle. Bpy molecules adsorb on the Cd2+-rich surface of the CdS cluster via the nitrogen ? donation, which was elucidated by the FT-Raman spectroscopy. AOT exists as an anion ion of AOTSO3? in the CdS/bpy composite.   

N. In the present report we present the results of an experimental ...... heavy bombardment,. (2) the global topography inherited by the planet from ...... ably excess metal present in the martian mantle that could react with ..... mud. Brine composition is assumed to be like that ofF_.ar&'s seawater, and ...... sumes adsorbents ...

We have prepared electrospun Nylon-6 nanofibers via electrospinning, and adsorbed multi-walled carbon nanotubes (MWCNTs) onto the surface of Nylon-6 fibers using Triton® X-100 to form a MWCNTs/Nylon-6 nanofiber composite. The dispersed MWCNTs have been found to be stable in hexafluoroisopropanol for...

Both correlation as well as prediction of experimental data for the adsorption of various binary liquid mixtures of alkanes and alkenes on NaX at different temperatures are presented. The theoretical background is based on the adsorbate-solid solution theory which conceives the adsorbed phase to be a mixture of the adsorbed species (adsorbate) and the adsorbent as an additional component. With the introduction of the Gibbs excess energy G{sup E*} for this hypothetical mixture, activity coefficients and composition of the adsorbed phase may be calculated. The Biggs excess energy and thus the activity coefficient of the adsorbed species depend strongly on the energetic heterogeneity of the solid surface which may be described by use of so-called group contribution models. These approaches, until now widely applied to predict fluid-phase equilibrium, are derived from statistical thermodynamics and take into account the energetic interactions between the respective components. For the application of this approach on thermodynamics of adsorption zeolites have to be divided into different functional groups such as SiO{sub 2}, AlO{sub 2}{sup {minus}}, and the respective cations. The interaction energies between these active sites and the functional groups of the adsorbed liquid molecules represent fundamental parameters of activity coefficient models based on group contributions such as UNIFAC. These parameters were determined by fitting four different adsorption systems. With the fitted values, six other systems were predicted. Both correlation and prediction include adsorption data at different temperatures. All calculations show excellent results with a mean relative deviation of 4.2% for the correlation and a mean deviation in the range of 8--17% for the predictions.

A superparamagnetic graphene-Fe(3)O(4) nanocomposite (G/Fe(3)O(4)) was synthesized by a facile one-pot solvothermal method. The nanocomposite G/Fe(3)O(4) prepared by the new method was firstly used as an adsorbent to remove dye for water pollution remediation. In comparison with G/Fe(3)O(4) prepared by the in situ chemical coprecipitation, the newly prepared G/Fe(3)O(4) had a higher adsorption efficiency for the dye. The adsorption characteristics of the nanocomposite adsorbent were examined using the organic dye pararosaniline as the adsorbate. The adsorption kinetics, adsorption capacity of the adsorbent, and the effect of the adsorbent dosage and solution pH on the removal efficiency of pararosaniline were investigated. The adsorption capacity of G/Fe(3)O(4) for pararosaniline was evaluated using the Freundlich and Langmuir adsorption isotherm models. The G/Fe(3)O(4) hybrid composite can be easily manipulated in magnetic field for desired separation, leading to an easy removal of the dye from polluted water. The G/Fe(3)O(4) hybrid composite would have a great potential in removing organic dyes from polluted water. PMID:23010021

Ion-Beam-Textured and Coated Surfaces Experiment (S1003) ... steel, and silver) ; (2) painted and/or state-of-the-art solar thermal surfaces (e.g., black ... for thermal and space charge control (e.g., indium-oxide-coated metalized FEP Teflon); ...

To protect turbine parts from oxidation, coatings of the nickel- chromium- ... These analyses showed that, without a barrier, diffusion of niobium (Nb) out of the. 6 phase of the y/yr - 6 ... oxidatiodhot- corrosion resistance of the materials. Recently ...

barium and barium oxide coated tungsten surfaces are prepared by evaporating barium ..... energy peaks in the oxidized barium layer, a similar phenomenon to that observed in the bulk barium experiments ..... 5 and 28). This cathode is sim- ...

results of the Apollo Program are digested. Aside from further ... spacecraft by microwave or laser with superimposed control signals or to the. Earth's surface to ...... chromium oxide coating has demonstrated reuse capability up to 1530°K and ...

The progress of research in the development of novel, rigid, monolithic adsorbent carbon fiber composites is described. Carbon fiber composites are produced at ORNL and activated at the CAER using steam or CO{sub 2} under different conditions, with the aims of producing a uniform degree of activation through the material, and of closely controlling pore structure and adsorptive properties The principal focus of the work to date has been to produce materials with narrow porosity for use in gas separations.

Lean NOx reduction shown to be strongly affected by HC reductant composition. Possibility exists to tailor exhaust HC composition by manipulating HC post-injection process. Why is this relevant if lean NOx catalysis ''isn't going to work'' ? Lean NOx (esp. with post-injection of HC) offers unmatched ''passiveness'' NOx adsorber technology will require reductant - potentially introduced the same way

The theoretical principles underlying the formation of oxide and, in particular, anodic oxide coatings on metals produced by chemical oxidation, anodizing in solutions, and anodizing in cold plasmas are reviewed. The mechanisms and conditions of anodic oxidation are described, and the structure of anodic oxide coatings on aluminum, magnesium, beryllium, zinc, cadmium, iron, cobalt, nickel, titanium, zirconium, tantalum, and chromium alloys is examined. Attention is also given to various applictins of anodized coatings. 54 references.

A composite consisting of two nanosized biocompatible components, Acetobacter xylinum cellulose and calcium phosphate, is prepared through aggregation in an aqueous suspension. The structures of initial components and composite are investigated by the methods of X-ray and electron diffraction and electron microscopy. The mineral component consists of two crystalline phases, hydroxyapatite and whitlockite (magnesium-containing tricalcium phosphate), which are nanosized platelike crystals. The composite preserves the crystalline structures of initial calcium phosphates and cellulose. In the course of composite formation, hydroxyapatite and whitlockite crystallites are adsorbed on the surfaces of nanofibrillar cellulose ribbons. Whitlockite nanocrystals are predominantly deposited on the surf...

Cell adhesion on biomaterial surfaces and the vitality of anchorage dependent cells is affected by several parameters of an adsorbate layer which is intentionally or spontaneously formed. Surface pre-treatments and several conditioning steps prior and during to the cell/biomaterial contact affect the composition, orientation, quantity and viscoelasticity of the interfacing layer between cells and biomaterial. This work was performed to elucidate the response of cells on two modified biomaterial surfaces based on protein or carbohydrate adsorbates:Masked UV irradiations opened a simple route to obtain chemically patterned substrates controlling serum protein adsorption and cell adhesion. It is possible to achieve structures of subcellular size and to produce immobilized gradients. In order ...

A sampling method of dioxins in atmosphere by using economical materials as monitoring indicators was proposed. The materials used were polyurethane foam, newspaper, and activated carbon paper filter. Among the adsorbents, polyurethane adsorbed the most amounts of dioxins. The TEQ values in spring and autumn seasons were 0.13 and 0.027 pg cm?2, respectively. The composition of dioxin congeners was compared with that obtained by the air-sampler one. As a result, the distribution pattern of dioxins approximately coincided with that of the air-sampler.   

Adsorption of glycine on Pt{111} under UHV conditions and in different aqueous environments was studied by XPS (UHV and ambient pressure) and NEXAFS. Under UHV conditions, glycine adsorbs in its neutral molecular state up to about 0.15 ML. Further deposition leads to the formation of an additional zwitterionic species, which is in direct contact with the substrate surface, followed by the growth of multilayers, which also consist of zwitterions. The neutral surface species is most stable and decomposes at 360K through a multi-step process which includes the formation of methylamine and carbon monoxide. When glycine and water are co-adsorbed in UHV at low temperatures (<170K) inter-layer diffusion is inhibited and the surface composition depends on the adsorption sequence. Water adsorbed on...

In surface catalysis, the adsorption of carbon monoxide on transition-metal electrodes represents the prototype of strong chemisorption. Notwithstanding significant changes in the molecular orbitals of adsorbed CO, spectroscopic experiments highlight a close correlation between the adsorbate stretching frequency and equilibrium bond length for a wide range of adsorption geometries and substrate compositions. In this work, we study the origins of this correlation, commonly known as Badger's rule, by deconvoluting and examining contributions from the adsorption environment to the intramolecular potential using first-principles calculations. Noting that intramolecular anharmonicity is preserved upon CO chemisorption, we show that Badger's rule for adsorbed CO can be expressed solely in terms of the tabulated Herzberg spectroscopic constants of isolated CO. Moreover, although it had been previously established using finite-cluster models that Badger's rule is not affected by electrical conditions, we find here th...

This study investigates As, Ni, Zn, Cd, and Pb removal onto limestone, starfish, black shale, and concrete from wastewater. Natural materials or waste products with a high capacity for heavy metals can be obtained and employed of with little cost. For investigating the neutralization capacity, the change in pH, Eh, and EC as a function of time was quantified. Of the adsorbing agents, concrete showed that the high neutralization efficiency for AMD and maintained the pH value above 11. The adsorption of heavy metals by the samples was influenced by compositions of adsorbing agents. The experimental results of desorption revealed that when the adsorption or precipitation occurs, there was no significant releasing from all adsorbing agents. In this study, the results suggest that concrete can be used successfully in the treatment of acid mine drainages with mixed metal-contaminated wastes.

The objective of this study was to optimize the preparation of treatment plant wastewater sludge adsorbents for application in water treatment. The optimal adsorption capacity was obtained with adsorbents prepared by pyrolysis at 700^oC for 3h. We studied the effect of binder type on the adsorbents, finding that their textural properties were not substantially affected by the addition of phenolic resins but their surface area was reduced by the presence of clayey soil. Analysis of the composition of surface groups in these materials revealed: (i) a high concentration of basic surface groups in non-activated pyrolyzed sludge, (ii) an increase in the concentration of basic surface groups after chemical activation, (iii) no modification in the concentration of carboxyl or basic groups with th...

We developed a spongiform adsorbent that contains Prussian blue, which showed a high capacity for eliminating cesium. An in situ synthesizing approach was used to synthesize Prussian blue inside diatomite cavities. Highly dispersed carbon nanotubes (CNTs) were used to form CNT networks that coated the diatomite to seal in the Prussian blue particles. These ternary (CNT/diatomite/Prussian-blue) composites were mixed with polyurethane (PU) prepolymers to produce a quaternary (PU/CNT/diatomite/Prussian-blue), spongiform adsorbent with an in situ foaming procedure. Prussian blue was permanently immobilized in the cell walls of the spongiform matrix and preferentially adsorbed cesium with a theoretical capacity of 167mg/g cesium. Cesium was absorbed primarily by an ion-exchange mechanism, and t...

In many high-temperature fossil energy systems, corrosion and deleterious reactions with gases and condensable products in the operating environment often compromise materials performance. The presence of a stable surface oxide (either as thermally-grown scales or deposited coatings) can effectively protect the materials from these reactions if the oxides are slow-growing, dense and adherent to the substrate. The protection these brittle oxide films provide has long been a critical issue, particularly for applications involving severe high-temperature thermal cycles or very aggressive (for example, sulfidizing) environments. The various factors which control the scale/coating integrity and adherence are not well understood. The present multilaboratory collaborative work is intended to define the relationships between substrate characteristics (composition, microstructure, and mechanical behavior) and the structure and protective properties of deposited oxide coatings and/or thermally grown scales. Through such studies, the ultimate goal is to assure environmental protection through effective processing and materials selection leading to the development of corrosion-resistant, high-temperature materials for improved energy and environmental control systems.

Tungsten oxide coatings were deposited without substrate bias by DC reactive magnetron sputtering of a tungsten target using oxygen as reactive gas. By tuning the partial pressure of oxygen (p {sub O{sub 2}}/p {sub Ar}) between 0 and 4, the oxygen content of the films was changed from 0 to 75 at.%. The structure of the films (investigated by X-ray diffraction) depends on their oxygen content. For low oxygen contents, the {alpha}-W and {beta}-W{sub 3}O phases were observed (< 30 at.%), and with the increase of oxygen content (30 at.% < O < 67 at.%) the structure became amorphous. A transition region was obtained for oxygen content between 67 at.% and 75 at.%, and when O > 75 at.%, a nanocrystalline (WO{sub 3}) structure was reached. The hardness and Young's modulus were evaluated by depth sensing indentation. The decrease in hardness followed the four different ranges of chemical compositions accordingly, from {approx} 23 GPa for pure W down to {approx} 7 GPa for WO{sub 3} films. A similar behaviour was observed for the Young's modulus, which ranged from 450 GPa to 150 GPa. The cohesion/adhesion of the films were investigated using a scratch-test apparatus. These coatings displayed a low adhesion (critical load, L {sub c} < 15 N) to the steel substrate because the depositions were carried out intentionally without an adhesion interfacial layer.

Uranium metal is pyrophoric and is capable of self-ignition in air provided conditions are favorable. Based on the data in this report, spontaneous ignition of spherical particles larger than 1/16 inch in diameter would not be expected to occur in air at room temperature (25{degree}C). The rate at which the uranium surface oxidizes in air, balanced against the rate at which the heat of reaction is lost to the surroundings, determines whether spontaneous ignition can occur. Heat loss to the surrounding environment depends on the thermal conductivity of the uranium including the oxide coating, and on the temperature gradient. The ignition temperature for uranium metal particles is a function of particle geometry, size or specific surface area, heating rate gas composition as well as the quantity and distribution of powder within a storage container. The most important variable; however, affecting the ignition temperature for single samples was found by Schnizlein and Bingle to be the specific surface area (surface area per gram) of the uranium particles. The ignition temperatures calculated from ANL data for 1/16, 1/4, and 1/2 inch diameter spherical particles are 333, 375, and 399{degree}C, respectively. The accuracy is believed to be about {plus_minus}l0%, which is based on theoretical and experimental results.

BP Solar first started investigative work on CdTe photovoltaics in 1986. The module product name chosen for the CdTe devices is Apollo. The deposition method chosen was electrochemical deposition due to its simplicity and good control of stoichiometric composition. The window layer used is CdS, produced from a chemical-bath deposition. Initial work focused on increasing photovoltaic cell size from a few mm2 to 900 cm2. At BP Solar's Fairfield plant, work is focused on increasing semiconductor deposition to 1 m2. The primary objective of this subcontract is to establish the conditions required for the efficient plating of CdS/CdTe on large-area, transparent conducting tin-oxide-coated glass superstrate. The initial phase concentrates on superstrate sizes up to 0.55 m2. Later phases will include work on 0.94 m2 superstrates. The tasks in this subcontract have been split into four main categories: (1) CdS and CdTe film studies; (2) Enhanced laser processing; (3) Outdoor testing program for the Apollo module; and (4) Production waste abatement and closed loop study.

The influence of yttrium oxide coating (processed by sol-gel method) on the oxidation behaviour of a commercial FeCrAl alloy (Kanthal A1) has been investigated during isothermal exposures in air at 1373K. The scale growth kinetic of the uncoated alloy obeys a parabolic rate law during the whole oxidation test whereas the kinetic curve of the Y-coated specimen exhibits an initial transient stage during the first hours, followed by a parabolic regime. The yttrium sol-gel coating deposited on the bare alloy does not conduct to the beneficial effect usually ascribed to the reactive elements. No oxidation rate improvement of the coated alloy is observed, the parabolic rate constants values are strictly identical for the both specimens. In situ X-ray diffraction reveals a marked influence of the reactive element on the composition of the oxide scale. The oxide layer formed on the yttrium-coated specimen revealed, in addition to ?-alumina which is the main oxide also identified on the bare specimen, the presence of yttrium aluminates (YAlO{3}, Y{3}Al{5}O{12}) located in the outermost part of the layer.

The effect of counterface selection on the tribological performance of a Ag/BaF2-CaF2 containing composite coating is studied. Ceramic (Al2O3) and metal (Inconel X-750) pins are slid against PS300 (a metal bonded chrome oxide coating with Ag and BaF2/CaF2 lubricant additives) in a pin-on-disk tribometer at 25, 500 and 650 C. Compared to the ceramic counterface, the metal counterface generally exhibited lower friction and wear at 25 C but higher friction and wear at 650 C. Friction coefficients, for example, for the Al2O3/PS300 combination at 25 C were 0.64 compared to 0.23 for the Inconel/PS300 sliding couple. At 650 C the ranking was reversed. The Al2O3/PS300 combination gave a friction coefficient of 0.19 while the friction for the metal counterface increased slightly to about 0.3. Based upon these tribological results and other information found in the literature, it appears that the performance of each counterface/PS300 combination is affected by the ability of the solid lubricant additives to form an adequate transfer film. The effects of surface wettability and tribological compatibility are discussed in relation to the observed tribological results.

Thick ceramic coatings were fabricated by microarc oxidation on 2024 aluminum alloy in a silicate solution. The phase composition and microhardness in the coatings were determined. The unlubricated tribological performance of the coatings was investigated using a SRV ball-on-disc friction and wear test system with reciprocating motion against sintered WC ball. The typical worn surfaces of the Al substrate and the ceramic coatings were observed by a scanning electron microscope. Under the same wear condition, the wear rates in different depth coatings are nearly similar. However, in a same depth of the coatings, wear rate gradually decreases with wear duration, and the lowest wear rate is less than 3.29×10?7 mm3/N m. During friction process, a WC transfer layer was formed on the tribo-contact area of the coatings, which takes advantage of decreasing the wear rate. The friction coefficient in a steady friction stage is about 0.52. After the Al alloy is treated by microarc oxidation, its wear resistance is improved over three orders of magnitude. The high wear resistance of the microarc oxidation coatings results from a nearly perfect distribution of ?-Al2O3 and ?-Al2O3 phases in the coating.   

The most common material system currently used for low thrust, radiation-cooled rockets is a niobium alloy (C-103) with a fused silica coating (R-512A or R-512E) for oxidation protection. However, significant amounts of fuel film cooling are usually required to keep the material below its maximum operating temperature of 1370 C, degrading engine performance. Also the R-512 coating is subject to cracking and eventual spalling after repeated thermal cycling. A new class of high-temperature, oxidation-resistant materials are being developed for radiation-cooled rockets, with the thermal margin to reduce or eliminate fuel film cooling, while still exceeding the life of silicide-coated niobium. Rhenium coated with iridium is the most developed of these high-temperature materials. Efforts are on-going to develop 22 N, 62 N, and 440 N engines composed of these materials for apogee insertion, attitude control, and other functions. There is also a complimentary NASA and industry effort to determine the life limiting mechanisms and characterize the thermomechanical properties of these materials. Other material systems are also being studied which may offer more thermal margin and/or oxidation resistance, such as hafnium carbide/tantalum carbide matrix composites and ceramic oxide-coated iridium/rhenium chambers.

A soluble alternating phenylenevinylene copolymer P containing a side anthracene, which was attached to the thiophene ring via a vinylene bridge, was synthesized by Heck coupling. The copolymer had relatively low glass transition temperature (61 C) and decomposed above 400 C. The absorption maximum of P was located at 387-402 nm with an optical band gap of 2.32 eV. The emission spectra of P indicated that an intramolecular energy transfer from the side anthracene to the main chain took place via the vinylene bridge. In addition, a new symmetrical compound A based on perylene-anthracene was synthesized and used as electron acceptor in the device. Photovoltaic devices were fabricated using a blend of copolymer P as donor and compound A as acceptor, as photoactive layer film sandwiched between indium tin oxide-coated glass and Al electrodes. This device showed a power conversion efficiency of 0.72%. However, when TiO{sub 2} nanoparticles were incorporated on the pristine P:A blend, the power conversion efficiency of the device was enhanced up to 1.32%, which is attributed to the enhanced photoinduced excitons due to the increase of the interfacial area and improved charge carrier mobility. The power conversion efficiency of the P:A:TiO{sub 2} based photovoltaic device was further improved up to 2.64%, when the hybrid composite was treated with a mixture of Li salt and 4-tert-butylpyridine, which is attributed to the reduction in the recombination of charge carriers. (author)

Removal of humic acid (HA) from water by octadecyltrimethyl-ammonium (ODTMA) micelle-montmorillonite (MMT) composites and by granulated activated carbon (GAC) was studied in dispersion and by filtration. FTIR measurements emphasized that the ODTMA micelle-clay-mineral composite differs from the ODTMA monomer-clay-mineral one. HA adsorption by GAC in dispersion was moderately reduced from 100% initially to 75% with an increase in HA concentrations. In contrast, the fractions adsorbed by the composite increased monotonically with HA concentrations from very low adsorption up to 80%. This effect was explained by the presence of a small concentration of ODTMA monomers in dispersion, which adsorbed on the negatively charged HA and partially neutralized it, or caused charge reversal, which in tu...

Silicalite-1/fly ash cenosphere (S/FAC) zeolite composite has been applied for batch adsorption of methyl tert-butyl ether (MTBE) from water systems. Here the key experimental conditions, including the ratio of initial MTBE concentration to the amount weight of S/FAC, adsorption time and temperature, have been discussed in detail. The results show that approximately 93-95% MTBE could be adsorbed with initial concentration of MTBE solution 1000mgl-1. The column flow-through experiments also prove the high capacity of S/FAC composite for MTBE removal. The distinct advantages of S/FAC zeolite composite as adsorbent lie in (1) enhanced adsorption rate and capacity based on hierarchical micro and meso/macroporosity of S/FAC; (2) more easily operation and recycling process by assembly of nano-si...

The adsorption of dimethyl sulfide from an aqueous solution by a cost-effective bamboo charcoal from Dendrocalamus was studied in comparison with other carbon adsorbents. The bamboo charcoal exhibited superior adsorption on dimethyl sulfide compared with powdered activated carbons at different adsorbent dosages. The adsorption characteristics of dimethyl sulfide onto bamboo charcoal were investigated under varying experimental conditions such as particle size, contact time, initial concentration and adsorbent dosage. The dimethyl sulfide removal was enhanced from 31 to 63% as the particle size was decreased from 24-40 to >300 mesh for the bamboo charcoal. The removal efficiency increased with increasing the adsorbent dosage from 0.5 to 10mg, and reached 70% removal efficiency at 10mg adsorbed. The adsorption capacity (?g/g) increased with increasing concentration of dimethyl sulfide while the removal efficiency decreased. The adsorption process conforms well to a pseudo-second-order kinetics model. The adsorption of dimethyl sulfide is more appropriately described by the Freundlich isotherm (R(2), 0.9926) than by the Langmuir isotherm (R(2), 0.8685). Bamboo charcoal was characterized by various analytical methods to understand the adsorption mechanism. Bamboo charcoal is abundant in acidic and alcohol functional groups normally not observed in PAC. A distinct difference is that the superior mineral composition of Fe (0.4 wt%) and Mn (0.6 wt%) was detected in bamboo charcoal-elements not found in PAC. Acidic functional group and specific adsorption sites would be responsible for the strong adsorption of dimethyl sulfide onto bamboo charcoal of Dendrocalamus origin. PMID:21549503

Coexisting arsenic (As) and fluoride (F) in groundwater poses severe health risks worldwide. Highly efficient simultaneous removal of As and F is therefore of great urgency and high priority. The purpose of this study was to fabricate a novel composite adsorbent and explore the mechanism for concurrent removal of As(V) and F at the molecular level. This bifunctional adsorbent with titanium and lanthanum oxides impregnated on granular activated carbon (TLAC) exhibits a pronounced As(V) and F adsorption capacity over commercially available iron- and aluminum-based adsorbents for synthetic and real contaminated groundwater samples. Synchrotron-based X-ray microfluorescence analysis demonstrates that La and Ti were homogeneously distributed on TLAC. Extended X-ray absorption fine structure spectroscopic results suggest that As(V) formed bidentate binuclear surface complex as evidenced by an averaged Ti-As bond distance of 3.34 Å in the presence of F. Adsorption tests and Fourier transform infrared spectroscopy analysis indicate that F was selectively adsorbed on lanthanum oxides. The surface configurations constrained with the spectroscopic results were formulated in the charge distribution multisite complexation model to describe the competitive adsorption behaviors of As(V) and F. The results of this study indicate that TLAC could be used as an effective adsorbent for simultaneous removal of As(V) and F. PMID:22235839

The interaction of methanol (CH{sub 3}OD) with polycrystalline uranium and UO{sub 2} has been studied by X-ray photoelectron spectroscopy (XPS), thermal desorption-mass spectrometry (TDMS) and secondary-ion mass spectrometry (SIMS) over the temperature range 90-500K. Low-temperature (90K) adsorption on uranium resulted in the formation of methoxy species along with condensed-phase adsorbed methanol. Room-temperature adsorption of methanol (or annealing an adsorbed methanol adlayer to 300K) on uranium produces a mixture of methoxy and a uranium oxycarbide. Further heating to 400K completely decomposes the adsorbed methoxy species, with 10% desorbing as methane and the remaining methoxide irreversibly converting to an uranium oxycarbide overlayer of nominal composition UO{sub 0.66}C{sub 0.34}. Concomitant with these carbon-fragment-conversion processes, desorption of hydrogen and deuterium are also seen over a wide temperature regime (325-450K). Methanol-d adsorption on UO{sub 2} also produces a methoxy surface species at surfaces temperatures <150K. Adsorbate decomposition following thermal desorption releases gaseous CH{sub 4}, H{sub 2}, HD, D{sub 2} and CO. Most of the oxygen derived from the methanol molecule (-90%) was incorporated into the UO{sub 2} layer and all of the adsorbed carbon desorbs from the surface as one of the molecular species identified above. The reactive adsorption and thermal decomposition of methanol at uranium and UO{sub 2} surfaces is compared with that observed at other metal and metal oxide surfaces

A novel adsorbent poly(methacrylic acid)-grafted chitosan/bentonite (CTS-g-PMAA/Bent) composite was prepared through graft copolymerization reaction of methacrylic acid and chitosan in the presence of bentonite (Bent) and N,N'- methylenebisacrylamide as a crosslinker. The composite was well characterized using FTIR, XRD, XPS, SEM-EDS, surface area and zeta potential analyzers. The adsorption behavior of the composite toward uranium(VI) from aqueous media was studied under varying operating conditions of pH, concentration of U(VI), contact time, adsorbent dose and temperature. The optimum pH range for U(VI) adsorption was 5.5 at 30 °C. Concentration and temperature dependent rate constants were evaluated using pseudo-second-order kinetic model. The equilibrium data were correlated with the Langmuir isotherm model with an endothermic behavior. The equilibrium U(VI) sorption capacity was estimated to be 117.2 mg g(-1) at 30 °C. For the quantitative recovery of 100 mg L(-1) U(VI) from 1.0 L simulated nuclear industry wastewater, a minimum adsorbent dosage of 2.0 g CTS-g-PMAA/Bent was required. The calculated energy of activation (E(a) = 47.83 kJ/mol) was positively correlated with chemical adsorption process. The values of enthalpy, entropy and free energy of activation were calculated to explain the nature of adsorption process. Adsorption-desorption experiments over four cycles illustrate the feasibility of the repeated uses of this composite for the extraction of U(VI) from aqueous solutions. PMID:22304995

Iron oxide/activated carbon (FeO/AC) composite adsorbent material, which was used to modify the coal-based activated carbon (AC) 12 x 40, was prepared by the special ferric oxide microcrystal in this study. This composite can be used as the adsorbent to remove arsenic from drinking water, and Langmuir isotherm adsorption equation well describes the experimental adsorption isotherms. Then, the arsenic desorption can subsequently be separated from the medium by using a 1% aqueous NaOH solution. The apparent characters and physical chemistry performances of FeO/AC composite were investigated by X-ray diffraction (XRD), nitrogen adsorption, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Batch and column adsorption experiments were carried out to investigate and compare the arsenic removal capability of the prepared FeO/AC composite material and virgin activated carbon. It can be concluded that: (1) the main phase present in this composite are magnetite (Fe(3)O(4)), maghemite (gamma-Fe(2)O(3)), hematite (alpha-Fe(2)O(3)) and goethite (alpha-FeO(OH)); (2) the presence of iron oxides did not significantly affect the surface area or the pore structure of the activated carbon; (3) the comparisons between the adsorption isotherms of arsenic from aqueous solution onto the composite and virgin activated carbon showed that the FeO/AC composite behave an excellent capacity of adsorption arsenic than the virgin activated carbon; (4) column adsorption experiments with FeO/AC composite adsorbent showed that the arsenic could be removed to below 0.01 mg/L within 1250 mL empty bed volume when influent concentration was 0.5mg/L. PMID:17434260

We report dispersion solution composition dependence of the adsorption layer structure and the physical and optical properties of aqueous phase-synthesized semiconductor nanoparticles (NPs). We synthesized cysteine (Cys)-capped CdSe NPs with well-defined core structures, dispersed them in a series of aqueous solutions with different compositions, and then investigated their adsorption layer structure and physical and optical properties. Each CdSe NP consisted of a (CdSe)33 or (CdSe)34 magic-sized cluster (d - 1.45 nm) core, a ligand-Cys shell, and an adsorption layer. The dispersion solution composition strongly affected the adsorption layer structure of the CdSe NPs. The solution with a composition close to that of the as-prepared solution stabilized the physical and optical properties of the NPs. The solution with a composition different from that of the as-prepared solution, however, resulted in large changes in their adsorption layer structure and thus their physical and optical properties. The solution composed of neutral or weakly charged Cys and Cd-Cys complexes led to the adsorption layer with low charge density and that destabilized the NPs. The solution containing only neutral or weakly charged forms of Cys, without Cd-Cys complexes, was favorable to the formation of a thick adsorption layer with low charge density and that destabilized the NPs. The amount of adsorbed Cys in the adsorption layer depended on the dispersion solution composition. However, the amount of adsorbed Cd-Cys complexes in the adsorption layer was almost constant regardless of the dispersion solution composition. PMID:22524016

Abstract Blends of linear polyethylene (PE) and isotactic polypropylene (iPP) with different average molar masses and a series of ethylene-propylene (EP) copolymers with different chemical composition as well as blends of PE, Ipp, and EP copolymers were separated using a carbon-column packing (Hypercarb) and gradients of 1-decanol or 2-ethyl-1-hexanol - 1,2,4-trichlorobenzene (TCB). The separation is based on full adsorption of linear PE on the carbon sorbent at temperature 160C. However, iPP is not adsorbed and elutes in size exclusion mode. The random EP copolymers have been adsorbed in the column packing and separated according to their average chemical composition after application of the gradient starting with alcohol and ending with pure TCB. The elution volumes of the copolymers dep...

Configurational-bias Monte Carlo (CBMC) simulations in the isobaric-isothermal version of the Gibbs ensemble (GE) were carried out to probe the adsorption from aqueous solutions of methanol and/or ethanol onto silicalite-1. This methodology does require neither specification of the chemical potential nor any reference to activity models based on experimental data. The CBMC-GE methodology can be applied to the complete range of mixture compositions from pure water to pure alcohols and can also be used when multiple solute types are present at high concentration. The simulations demonstrate high selectivities for the alcohols (?(ethanol) > ?(methanol)) almost over the entire composition range. The ideal adsorbed solution theory is found to substantially underpredict the amount of sorbed water and leads to very large errors for low alcohol solution concentrations. The simulations indicate that, at lower loadings, the adsorbed alcohol molecules can serve as seeds for water adsorption but, at higher loadings, alcohols displace water molecules from their preferred region. PMID:23050981

This article presents a facile method for the preparation of polystyrene/silver (PS/Ag) composite microspheres. In this approach, monodisperse PS spheres were synthesized via dispersion polymerization and modified by sulfonation to obtain sulfonated PS spheres with sulfonic acid groups on the surfaces, and then adsorbed Sn2+ ions by electrostatic interaction and used as templates. PS/Ag composite microspheres were prepared successively by addition of [Ag(NH3)2]+ complex ions to the templates dispersion, adsorbing to the surfaces of templates, and then reduction of [Ag(NH3)2]+ complex ions to Ag nanoparticles by sodium potassium tartrate. The results showed that monodisperse PS spheres with sulfonic acid groups on the surfaces were coated by an incomplete and nonuniform coverage of Ag nanop...

Solid sorption refrigeration is a type of environmental benign and energy saving technology and the sorbents utilized can be divided into physical, chemical and composite sorbents, according to the nature of the forces involved in the adsorption process. The types, characteristics, advantages and disadvantages of different adsorbents, refrigerants and working pairs are summarized in this paper, together with the models that describe the adsorption equilibrium. Moreover, some of the procedures to prepare composite adsorbents are presented. The application of different working pairs for different situations is related with the adsorption heat, the adaptability to the driving temperature and to the desired working pressure. The methods to measure the adsorption quantity of different working pairs are compared, and future research directions of adsorption working pairs are also analyzed. (author)

A test setup was built to study the adsorption performance of the composite adsorbent used in the adsorption system. The isovolume measurement method is adopted in the test setup to measure the adsorption isosteres of the composite adsorbent and ammonia working pair. The adsorption isosteres are the curves of the adsorption pressures variation with adsorption temperatures at constant adsorption quantity, which are convenient for the calculation of the adsorption heat and selection of the adsorption working pairs. The adsorption heats were calculated according to the adsorption isosteres, three clear crest values indicate that there were three types of reaction during the reaction processes of ammoniate calcium chloride and ammonia. The kinetic model of adsorption isosteres is obtained by the Temkin model, it is useful to estimate the adsorption performance of the working pairs and useful to guide the design of adsorption system.

The goal of this work is to study the purification of biodiesel from waste frying oil (WFO) using rice husk ash (RHA) at concentrations of 1%, 2%, 3%, 4% and 5% (w/w) and compare it with two other different purification methods, the traditional acid solution (1% aqueous H3PO4) and with the commercial adsorbent Magnesol 1% (w/w). The structure and composition of the RHA were studied to better understand its properties as an adsorbent. In a concentration of 4%, the RHA showed excellent results for removal impurities from biodiesel. The high concentration of silica in its composition and the presence of meso and macropores can explain its high capacity of adsorption. Thus, the RHA, that is a byproduct of the rice processing, can appear as an alternative material for biodiesel purification.

Abstract Mixed self-assembled monolayers (SAMs) consisting of different molecules have been used to modify surface wettability, functionalize end groups for chemical binding, and control adsorption of proteins, DNA, or cells. In these applications, control over the quantification of the surface composition of a mixed SAM is especially important when designing biochips and biosensors. Previously, we presented a method by which ToF-SIMS can be used to quantify the composition of two adsorbates with acetylene and propene functional groups from their secondary ion yield ratio in mixed SAMs on gold substrates. We concluded that although the ion yield ratio of the two adsorbates in mixed SAM was not equal to the mole fraction of Diyne (-acetylene) and Diene (-propene) in a solution, this was due...

Abstract Magnetic maghemite (-Fe2O3)/chitosan nanocomposite films were prepared by solution casting method and characterized by Fourier transform infrared spectra, thermogravimetric analysis, differential scanning calorimetry and X-ray diffraction. Batch adsorption experiments were carried out utilizing the composite films to adsorb a typical azo dye, i.e., methyl orange (MO) from aqueous solutions. The effects of adsorbent dosage, solution pH, coexisting anions, and temperature were studied. Adsorption kinetic was verified by pseudo-first-order and pseudo-second-order kinetic models. Results indicated that the rate of dye adsorption followed pseudo-second-order kinetic model for the initial dye concentration range studied. MO adsorption onto magnetic -Fe2O3/chitosan composite films was be...

The present study aimed at development of capsular dosage form of surface-adsorbed nanoemulsion (NE) of olmesartan medoxomil (OLM) so as to overcome the limitations associated with handling of liquid NEs without affecting their pharmaceutical efficacy. Selection of oil, surfactant, and cosurfactant for construction of pseudoternary phase diagrams was made on the basis of solubility of drug in these excipients. Rationally selected NE formulations were evaluated for percentage transmittance, viscosity, refractive index, globule size, zeta potential, and polydispersity index (PDI). Formulation (F3) comprising of Capmul MCM® (10% v/v), Tween 80® (11.25% v/v), polyethylene glycol 400 (3.75% v/v), and double-distilled water (75% v/v) displayed highest percentage cumulative drug release (%CDR; 96.69?±?1.841), least globule size (17.51?±?5.87 nm), low PDI (0.203?±?0.032), high zeta potential (-58.93?±?0.98 mV), and hence was selected as the optimized formulation. F3 was adsorbed over colloidal silicon dioxide (2 ml/400 mg) to produce free-flowing solid surface-adsorbed NE that presented a ready-to-fill capsule composition. Conversion of NE to surface-adsorbed NE and its reconstitution to NE did not affect the in vitro release profile of OLM as the similarity factor with respect to NE was found to be 66% and 73% respectively. The %CDR after 12 h for optimized NE, surface-adsorbed NE, and reconstituted NE was found to be 96.69?±?0.54, 96.07?±?1.76, and 94.78?±?1.57, respectively (p?>?0.05). The present study established capsulated surface-adsorbed NE as a viable delivery system with the potential to overcome the handling limitations of NE. PMID:22965661

The NH{sub 2}-MIL-53(Al) metal-organic framework was studied for its use in the separation of CO{sub 2} from CH{sub 4}, H{sub 2}, N{sub 2} C{sub 2}H{sub 6} and C{sub 3}H{sub 8} mixtures. Isotherms of methane, ethane, propane, hydrogen, nitrogen, and CO{sub 2} were measured. The atypical shape of these isotherms is attributed to the breathing properties of the material, in which a transition from a very narrow pore form to a narrow pore form and from a narrow pore form to a large pore form occurs, depending on the total pressure and the nature of the adsorbate, as demonstrated by in-situ XRD patterns measured during adsorption. Apart from CO{sub 2}, all tested gases interacted weakly with the adsorbent. As a result, they are excluded from adsorption in the narrow pore form of the material at low pressure. CO{sub 2} interacted much more strongly and was adsorbed in significant amounts at low pressure. This gives the material excellent properties to separate CO{sub 2} from other gases. The separation of CO{sub 2} from methane, nitrogen, hydrogen, or a combination of these gases has been demonstrated by breakthrough experiments using pellets of NH{sub 2}-MIL-53(Al). The effect of total pressure (1-30 bar), gas composition, temperature (303-403 K) and contact time has been examined. In all cases, CO{sub 2} was selectively adsorbed, whereas methane, nitrogen, and hydrogen nearly did not adsorb at all. Regeneration of the adsorbent by thermal treatment, inert purge gas stripping, and pressure swing has been demonstrated. The NH{sub 2}-MIL-53(Al) pellets retained their selectivity and capacity for more than two years.

Magnetic composite nanoparticle of Au/?-Fe2O3 was synthesized in an aqueous phase using gamma-ray. Connection between gold and ?-Fe2O3 was confirmed by the magnetic separation technique. TEM observation shows that 5-nm gold particles were dispersed on 20-nm ?-Fe2O3 particles. The nanoparticles adsorbed a water-soluble mercaptan, glutathione, and was manipulated by an external magnetic field.   

Transformation of propene adsorbed on ZnO in a closed reactor at 296-623 K has been monitored with 1H and 13C solid-state NMR spectroscopy. Propane was detected to be formed as one of the reaction products and a simple aromatics of the average composition C7H8 as the other product. The mechanism of propene disproportionation, detected for the first time on zinc oxide catalyst, is discussed.

Catalysed N{sub 2}O decomposition has been studied on hydrotalcite like compounds. An important effect of the mixed oxide composition has been observed. Cobalt and, specially, rhodium, seem to have a decisive role in the catalytic activity of these samples. The reaction mechanism has been studied with the aid of the TEOM microbalance. The mass variation during reaction could be fitted to a model in which several adsorbed states of oxygen are considered. (Author)

Separation of astatine has been carried out by distillation from molten metallic bismuth irradiated with ..cap alpha..-particles in helium flow. Astatine has been adsorbed from the gas phase onto a silver foil and then distilled into solutions of a given composition. By this method alkaline, neutral and acidic solutions of a specific activity up to 1000 mCi/ml (37 GBq/ml) in a volume of 30-100 ..mu..l could be obtained.

Evaluating societal risks posed by uranium contamination from waste management facilities, mining sites, and heavy industry requires knowledge about uranium transport in groundwater, often the most significant pathway of exposure to humans. It has been proposed that uranium mobility in aquifers may be controlled by adsorption of U(VI)-carbonato complexes on oxide minerals. The existence of such complexes has not been demonstrated, and little is known about their compositions and reaction stoichiometries. The authors have used attenuated total reflectance Fourier transform infrared (ATR-FTIR) and extended X-ray absorption fine structure (EXAFS) spectroscopies to probe the existence, structures, and compositions of [triple bond]FeO[sub surface]-U(VI)-carbonato complexes on hematite throughout the pH range of uranyl uptake under conditions relevant to aquifers. U(VI)-carbonato complexes were found to be the predominant adsorbed U(VI) species at all pH values examined, a much wider pH range than previously postulated based on analogy to aqueous U(VI)-carbonato complexes, which are trace constituents at pH < 6. This result indicates the inadequacy of the common modeling assumption that the compositions and predominance of adsorbed species can be inferred from aqueous species. By extension, adsorbed carbonato complexes may be of major importance to the groundwater transport of similar actinide contaminants such as neptunium and plutonium.

New composites based on HKUST-1 and graphene layers are tested for ammonia adsorption at room temperature in both dry and moist conditions. The materials are characterized by X-ray diffraction, FT-IR spectroscopy, adsorption of nitrogen, and thermal analyses. Unlike other MOF/GO composites reported in previous studies, these materials are water-stable. Ammonia adsorption capacities on the composites are higher than the ones calculated for the physical mixture of components, suggesting the presence of a synergetic effect between the MOF and graphene layers. The increased porosity and dispersive forces being the consequence of the presence of graphene layers are responsible for the enhanced adsorption. In addition to its retention via physical forces, ammonia is also adsorbed via binding to the copper sites in HKUST-1 and then, progressively, via reaction with the MOF component. This reactive adsorption is visible through two successive changes of the adsorbents' color during the breakthrough tests. More ammonia is adsorbed in moist conditions than in dry conditions owing to its dissolution in a water film present in the pore system. PMID:20825199

In this article, we showed that simple metal oxide coatings such as MoO3 can be an effective enhancer for carbon nanotubes (CNTs) in field emission (FE) performance. For comparison, the FE properties of the pristine vertically aligned multi-walled CNTs with the metal oxide-coated CNTs were investigated. The metal oxide coating of the pristine CNTs was carried out by metal?organic chemical vapor deposition (MOCVD) method at 400??C using Mo(CO)6 as the precursor. The core?shell structure of the nanocomposite was studied by transmission electron microscopy (TEM). X-ray photoelectron spectroscopy (XPS) results showed that the surface of the coating material was mainly MoO3. FE test indicated that the MoO3-coated CNTs film exhibited an enhanced performance than the pristine CNTs with a turn-on ...

Disclosed is a method of reducing the removal or transfer into a gas phase of a current carrying metal in an apparatus, such as an electrochemical cell 2 having a porous fuel electrode 6 containing metal particles 11, where the metal is subject to removal or transfer into a gaseous phase, the method characterized in that (1) a metal organic compound that decomposes to form an electronically conducting oxide coating when heated is applied to the metal and porous electrode, and (2) the compound on the metal is then heated to a temperature sufficient to decompose the compound into an oxide coating 13 by increasing the temperature at a rate that is longer than 1 hour between room temperature and 600.degree. C., resulting in at least one continuous layer 13, 14 of the oxide coating on the metal.

Here we demonstrate thermal energy storage cement mortar (TESCM) fabricated by integrating ordinary cement mortar with a composite phase change material (PCM) based on n-octadecane and expanded graphite (EG). The mass percentage of n-octadecane in the composite PCM can reach as high as 90% due to the excellent adsorption ability of EG, which endows the composite PCM with large latent heat. SEM images of the composite PCM show that n-octadecane is adsorbed into the pores of EG and uniformly covers on the nanosheets of EG, which microstructure contributes to preventing leakage of melted n-octadecane after it changes phase from solid state to liquid state. The n-octadecane/EG composite PCM has a good compatibility with ordinary cement mortar, and does not obviously deteriorate the apparent de...

The aluminum-carbon nanotube composite (Al-CNT composite) much improves the properties of aluminum such as the toughness and the electrical conductivity. However, the manufacturing procedure for producing the Al-CNT composite requires multistage processes. We obtained electrolytically the Al-CNT composite coating from a 66.7 mol%AlCl3–33.3 mol%1-ethyl-3-methylimidazolium chloride bath containing CNT in a single process for the first time. We also visualized and clarified the process whereby solid particle such as CNT was co-deposited with the aluminum, and proved the co-depositing mechanism that previously had been understood only theoretically and conceptually. Namely, we show that the CNT was adsorbed on the cathode, and immediately seized by the initial depositing nucleus of the aluminum, then completely covered by both the grown nucleus and the newly generated initial depositing nuclei, and finally buried in the composite.   

Sorption to iron-oxide coated sand (IOCS) is a promosing technology for removal of the dissolved heavy metal fraction in stormwater runoff. The development of a new technology is necessary since studies of stormwater runoff from traffic areas indicate that an oil separator and detention pond may not guarantee that emission limit values set by the Danish EPA are satisfied. Runoff water was sampled from an urban highway, allowed to settle for 24 hours to simulate the effect of a detention pond, and finally spiked with metals to ensure concentration levels similar to high levels reported in the leterature (Pb=20, Cu=40, Zn=110, and Cr=15 ppb). Column experiments were conducted to test the influence of the infiltration rate (1 or 3 m/h) and the type of iron(hydr)oxide mineral (amorphous ferrihydrite and goethite coated sand). The results show that at least 90% of lead, copper and zinc can be removed by IOCS after 480 pore volumes. Control columns with uncoated filter sand show that lead, copper and zinc were removed with >95%, 35% and 5%, respectively. The removal of the negative metaloxy-ion, CrO4-3 was insignificant in both IOCS and sand columns at pH=7.7. Destruction of the columns after the experiments showed, that Pb, Cu and Zn penetrated to different depths in the columns. No saturation of lead was found in the first cm of the column after 1696 pore volumes of teated water. Copper showed a curved adsorption front, indicating that an infiltration speed of 3 m/h is sligtly too fast for the equilibrium between water phase and IOCS to be reached. The column with ferrihydrite was fully saturated with regard to zinc after 1696 pore volumes. In general the coating of goethite is found to be at least twice as effective as ferrihydrite with respect to the adsorption capacity of copper and zinc. Furthermore, desorption of metals from the IOCS by soaking in weak acid (pH=2.25) showed that 20%, 58% and 75% of the adsorbed Pb, Cu and Zn was recovered. Reuse of the IOCS after soaking in weak acis is possible, but it is likely to lower the adsorption capacities found in this study.

Natural variations in the ratio of 238U/235U due to “stable” isotope fractionation have now been reported for a range of geological samples [1-3]. Among the observed variations are a small difference in 238U/235U between seawater and ferromanganese sediments (seawater slightly heavier) and a larger difference, with opposite sense, between seawater and black shales (seawater lighter). These variations suggest that long-term changes in the proportions of oxic and anoxic/sulfidic sinks for U in the ocean over Earth’s history may be recorded as shifts in the isotopic compositions of marine sediments. Thus U isotopes are a potential paleoredox proxy for the oceans, as suggested by [4]. In order to investigate the mechanism behind fractionation of U isotopes in oxidizing marine environments, we previously conducted simple adsorption experiments in which an isotopically known pool of dissolved U partly adsorbed onto synthetic birnessite, a common Mn oxyhydroxide in hydrogenetic ferromanganese crusts. Our experimental result agreed very well with that observed between seawater and natural ferromanganese sediments: ?238U/235U of adsorbed U was 0.2‰ lighter than ?238U/235U of dissolved U [5]. The magnitude of fractionation is constant as a function of experimental duration and fraction of U adsorbed, suggesting an equilibrium isotope effect. Many metal isotope effects are driven by changes in oxidation state for the metal of interest. Because both dissolved and adsorbed U are hexavalent in this system, a redox reaction cannot be causing isotope fractionation. We therefore hypothesized that a difference in uranium’s coordination environment between dissolved and adsorbed U is likely responsible for the isotope effect. We analyzed a sample from our experimental study with extended X-ray absorption fine structure (EXAFS) spectroscopy. Comparison of the EXAFS spectrum of U adsorbed on birnessite with the spectra of aqueous U species (UO22+ and UO2(CO3)34-) reveals subtle, but important differences in the U-O coordination shell between dissolved and adsorbed U. In particular, there is an increase in disorder in the bond distances to equatorial oxygens in the adsorbed complex. Our EXAFS data support our hypothesis that a difference in coordination chemistry drives the isotope effect observed in our experiments. The same mechanism may well explain the U isotope fractionation observed between seawater and hydrogenetic ferromanganese nodules, although a similar investigation of U isotope behavior during adsorption to Fe oxyhydroxides should be undertaken. [1] Weyer et al. (2008) GCA 72, 345. [2] Stirling et al. (2007) EPSL 264, 208. [3] Bopp et al. (2009) Geology, 37, 611. [4] Montoya-Pino et al. (2010) Geology 38, 315. [5] Brennecka et al. (2008) GCA 72(12) Suppl., A114.

The elution behavior of linear polyethylene and isotactic, atactic and syndiotactic polypropylene was tested using three different carbon column packings: porous graphite (Hypercarb), porous zirconium oxide covered with carbon (ZirChrom-CARB), and activated carbon TA 95. Several polar solvents with boiling points above 150°C were selected as mobile phases: 2-ethyl-1-hexanol, n-decanol, cyclohexylacetate, hexylacetate, cyclohexanone, ethylene glycol monobutyl ether and one non-polar solvent, n-decane. Polyethylene standards were completely or partially adsorbed in all tested sorbent/solvent systems. Polypropylene standards were partially adsorbed on Hypercarb and carbon TA95, but did not adsorb on ZirChrom-CARB. ZirChrom-CARB retained polyethylene pronouncedly when 2-ethyl-1-hexanol, cyclohexylacetate or hexylacetate were used as mobile phases at temperature 150 or 160°C, while all three basic stereoisomers of polypropylene eluted in size exclusion mode in these sorbent/solvent pairs. This is very different from the system Hypercarb/1-decanol, which separated polypropylene according to its tacticity. The opposite elution behavior of polyethylene and polypropylene in system ZirChrom-CARB/2-ethyl-1-hexanol (polypropylene eluted, polyethylene fully adsorbed) enabled to realize separation of blends of polyethylene and polypropylene. Ethylene/1-hexene copolymers were separated according to their chemical composition using system Hypercarb/2-ethyl-1-hexanol/1,2,4-trichlorobenzene. PMID:21035809

Investigations of the properties of absorbed monolayers have received great experimental and theoretical attention recently, both because of the importance of surface processes in practical applications such as catalysis, and the importance of such systems to the understanding of the fundamentals of thermodynamics in two dimensions. We have adapted the composite bolometer technology to the construction of microcalorimeters. For these calorimeters, the adsorption substrate is an evaporated film deposited on one surface of an optically polished sapphire wafer. This approach has allowed us to make the first measurements of the heat capacity of submonolayer films of /sup 4/He adsorbed on metallic films. In contrast to measurements of /sup 4/He adsorbed on all other insulating substrates, we have shown that /sup 4/He on silver films occupies a two-dimensional gas phase over a broad range of coverages and temperatures. Our apparatus has been used to study the heat capacity of Indium flakes. CO multilayers, /sup 4/He adsorbed on sapphire and on Ag films and H/sub 2/ adsorbed on Ag films. The results are compared with appropriate theories. 68 refs., 19 figs.

Adsorption and condensation are critical to many applications of porous materials including filtration, separation, and the storage of gases. Integral methods are used to derive an analytical expression describing fluid condensation pressures in slit pores bounded by parallel plane walls. To obtain this result, the governing equations of Density Functional Theory (DFT) are integrated across the pore width assuming that fluid densities within adsorbed layers are spatially uniform. The thickness, density, and energy of these layers are expressed as composite functions constructed from asymptotic limits applicable to small and large pores. By equating the total energy of the adsorbed layers to that of a liquid-full pore, the authors arrive at a closed-form expression for the condensation pressure in terms of the pore size, surface tension, and Lennard-Jones parameters of the adsorbent and adsorbate molecules. The resulting equation reduces to the Kelvin equation in the large-pore limit. It further reproduces the condensation pressures computed by means of the full DFT equations for all pore sizes in which phase transitions are abrupt. Finally, in the limit of extremely small pores, for which phase transitions may be smooth and continuous, this simple analytical expression provides a good approximation to the apparent condensation pressure indicated by the steepest portion of the adsorption isotherm computed via DFT.

Abstract in english Lipid nanoemulsions have recently been proposed as parenteral delivery systems for poorly-soluble drugs. These systems consist of nanoscale oil/water dispersions stabilized by an appropriate surfactant system in which the drug is incorporated into the oil core and/or adsorbed at the interface. This article reviews technological aspects of such nanosystems, including their composition, preparation methods, and physicochemical properties. From this review, it was possible t (more) o identify five groups of nanoemulsions based on their composition. Biopharmaceutical aspects of formulations containing some commercially available drugs (diazepam, propofol, dexamethasone, etomidate, flurbiprofen and prostaglandin E1) were then discussed.

Abstract in english Two bentonite clays with different mineralogical compositions from Mendoza, Argentine, were activated with H2SO4 solutions of 4 and 8 N at 90ºC for 3.5 hours. This treatment affected clay structural properties, as was shown by thermogravimetry, infrared spectrometry and chemical analysis. Bleaching efficiency for sunflower oil was strongly dependent on the acid concentration used for clay activation. The samples have bleaching capacity comparable to that observed with a (more) commercial adsorbent standard. The mineralogical composition of natural clays influenced the properties of the activated clays.

Abstract Polyelectrolyte blend films and membranes were prepared upon alternating electrostatic adsorption of polyallylamine hydrochloride (PAH) and mixtures of polystyrene sulfonate (PSS) and polyacrylic acid (PAA) in different ratio on solid supports. Infrared studies indicated that the PSS-PAA blend composition of the films always differed from the mixture composition in the dipping solution, PSS being preferentially adsorbed. Films deposited on porous supporting membranes (polyacrylonitrile/polyethylene terephthalate) were studied on their ion permeation under diffusion dialysis conditions, and their flux and salt rejection under nanofiltration and reverse osmosis (RO) conditions. Blend membranes prepared at pH 1.7 exhibit a significantly improved anion separation and salt rejection, t...

It is shown that in LC of polymers, the interaction parameter in ternary mobile phases can be described by a plane, which is determined by the dependencies in binary mobile phases. Instead of a critical adsorption point, critical conditions are observed along a straight line of composition between the two critical points in binary mobile phases. Consequently, a separation of block copolymers under critical conditions for one block by an adsorption mechanism for the other block can be achieved in ternary mobile phases of different compositions, which allows an adjustment of the retention of the adsorbing block.

Graphene composites were prepared by hydrothermal method using titanium dioxide (TiO2) adsorbed graphene oxide (GO) sheets as precursors. Free-standing hybrid films for lithium-ion batteries were prepared by adding TiO2/graphene composites to the polyvinylidene fluoride (PVdF)/N-methyl-2-pyrrolidone (NMP) solution, followed by a solvent evaporation technique. These films were characterized by atomic force microscopy (AFM), X-ray diffraction (XRD), scanning electron microscopy (SEM) and various electrochemical techniques. Flexible films show an excellent cycling performance, which was attributed to the interconnected graphene conducting network, which depressed the increasing of electric resistance during the cycling.

Biofunctional coatings are necessary to improve integration of titanium implants in the host tissue but they may be detrimental for the implant fatigue properties. This study presents an attempt towards enhancement of the in vitro fatigue strength of plasma electrolytic oxidation coated Ti6Al4V alloy by applying shot peening process prior to coating. The electrolytic oxidation was performed in calcium acetate and calcium glycerophosphate electrolytes that allowed formation of porous oxide coatings with high surface free energy and apatite like ability. A deformed surface layer coupled with induced residual compressive stresses seem to affect oxide growth rate and fatigue behavior of the titanium alloy.

Up to now inorganic adsorbents has been known to effective for treatment of radioactive waste containing metal ions due to their high selectivity toward the specific ions(Cs{sup +}, Sr{sup 2+}, Co{sup 2+}, Ag{sup +} ...). The draw back of this adsorption system is in the operation difficulties such as separation of fine solids (adsorbents) and pressure drop ({delta}p) problem. To come over these problems, preparation of composite adsorbents has been attempted. In our study, PAN-inorganic ion exchanger(Ni{sub 2}Fe(Cn){sub 6}, K{sub 2}Ti{sub 4}O{sub 9}) composite beads were prepared in the range of 0.5 {approx} 3.5mm in size. The selectivity for Ag{sup +}, Sr{sup 2+}, Cs{sup +} and Co{sup 2+} ions in binary and tertiary systems in composite beads was Sr{sup 2+}>Ag{sup +}, Ag{sup +}>Co{sup 2+}, Co{sup 2+}>Sr{sup 2+} and Sr{sup 2+}>Co{sup 2+}>Ag{sup +} respectively. As an selective Cs{sup +} adsorbent, 1,3-Dipropyloxycalix(4)arene crown ether (CCE1) and 1,3-Dipropyl-oxycalix(4)arene dibenzo crown ethers(CCE2) were also successfully synthesized in the fixed 1,3-alternate conformation with good yields by the reaction of corresponding 1,3-Dipropyloxy-calix(4)arenes 3 with pentaethylene glycol ditosylate and dibenzodimesylate 7, respectively in acetonitrile in the presence of cesium carbonate as a base. Solvent extraction of cesium picrates and cesium nitrate from aqueous solutions into chloroform were investigated. (author). 37 refs., 60 figs., 7 tabs.

As a low-cost natural adsorbent, diatomite (DA) (2??m) has several advantages including high surface area, chemical reactivity, hydrophilicity and lack of toxicity. In this study, the protein adsorption performance of supermacroporous composite cryogels embedded with Ni(2+) -attached DA particles (Ni(2+) -ADAPs) was investigated. Supermacroporous poly(2-hydroxyethyl methacrylate) (PHEMA)-based monolithic composite cryogel column embedded with Ni(2+) -ADAPs was prepared by radical cryo-copolymerization of 2-hydroxyethyl methacrylate (HEMA) with N,N'-methylene-bis-acrylamide (MBAAm) as cross-linker directly in a plastic syringe for affinity purification of human serum albumin (HSA) both from aqueous solutions and human serum. The chemical composition and surface area of DA was determined by XRF and BET method, respectively. The characterization of composite cryogel was investigated by SEM. The effect of pH, and embedded Ni(2+) -ADAPs amount, initial HSA concentration, temperature and flow rate on adsorption were studied. The maximum amount of HSA adsorption from aqueous solution at pH 8.0 phosphate buffer was very high (485.15?mg/g DA). It was observed that HSA could be repeatedly adsorbed and desorbed to the embedded Ni(2+) -ADAPs in poly(2-hydroxyethyl methacrylate) composite cryogel without significant loss of adsorption capacity. The efficiency of albumin adsorption from human serum before and after albumin adsorption was also investigated with SDS-PAGE analyses. PMID:21739602

Small stationary diesel engines, like in generator sets, have limited emission control measures and are therefore responsible for 44% of the particulate matter (PM) emissions in the United States. The diesel exhaust composition depends on operating conditions of the combustion engine. Furthermore, the measurements are influenced by the used sampling method. This study examines the effect of engine loading and exhaust gas dilution on the composition of small-scale power generators. These generators are used in different operating conditions than road-transport vehicles, resulting in different emission characteristics. Experimental data were obtained for gaseous volatile organic compounds (VOC) and PM mass concentration, elemental composition and nitrate content. The exhaust composition depends on load condition because of its effect on fuel consumption, engine wear and combustion temperature. Higher load conditions result in lower PM concentration and sharper edged particles with larger aerodynamic diameters. A positive correlation with load condition was found for K, Ca, Sr, Mn, Cu, Zn and Pb adsorbed on PM, elements that originate from lubricating oil or engine corrosion. The nitrate concentration decreases at higher load conditions, due to enhanced nitrate dissociation to gaseous NO at higher engine temperatures. Dilution on the other hand decreases PM and nitrate concentration and increases gaseous VOC and adsorbed metal content. In conclusion, these data show that operating and sampling conditions have a major effect on the exhaust gas composition of small-scale diesel generators. Therefore, care must be taken when designing new experiments or comparing literature results. PMID:16933642

Previous studies have demonstrated that gas phase H2S can immobilize certain redox-sensitive contaminants (Cr, U, Tc, etc.) in vadose zone environments. A key issue for effective and efficient delivery of H2S in these environments is its reactivity with indigenous iron oxides. To elucidate the factors that control the transport of H2S in the vadose zone, laboratory experiments were conducted to determine reaction mechanisms and rates of H2S oxidation by iron oxide coated sands using several carrier gas compositions and variable flow rates. Most experiments were conducted using ferrihydrite-coated sand. Additional studies were conducted with goethite and hematite coated sand and a natural sediment. Column experiments were conducted with 200 ppmv H2S in a carrier gas at three flow rates. Three carrier gases were used; N2, Air and O2. Selective extractions were conducted at the end of each column experiment to determine the mass balance of the reaction products for support of the postulated reaction pathways. XPS was used to confirm the presence of the reaction products. Results from the column experiments containing ferrihydrite indicate that when N2 is used as the carrier-gas, the major H2S oxidation products are FeS and elemental sulfur (S0). The ratios of FeS/S0 at the end of these experiments were consistent with the stoichiometry of the postulated reactions. When air or O2 were used as the carrier gas, S0 become the dominant reaction product along with FeS2 and smaller amounts of FeS, sulfate and thiosulfate.

The influence of various reactive-element (RE) oxide coatings (Y{sub 2}O{sub 3}, CeO{sub 2}, La{sub 2}O{sub 3}, CaO, HfO{sub 2}, and Sc{sub 2}O{sub 3}) on the oxidation behavior of pure Cr, Fe-26Cr, Fe-16Cr and Ni-25Cr at 900{degrees}C in O{sub 2} at 5 x 10{sup {minus}3} torr has been investigated using the {sup 18}O/SIMS technique. Polished samples were reactively sputter-coated with 4 nm of the RE oxide and oxidized sequentially first in O{sub 2} and then in {sup 18}O{sub 2}. The effectiveness of each RE on the extent of oxidation-rate reduction varied with the element used. Y{sub 2}O{sub 3} and CeO{sub 2} coatings were found to be the most beneficial, whereas Sc{sub 2}O{sub 3} proved to be ineffective, for example, for the oxidation of Cr. SIMS sputter profiles showed that the maximum in the RE profile moved away from the substrate oxide interface during the early stages of oxidation. After a certain time the RE maximum remained fixed in position with respect to this interface, its final relative position being dependent on the particular RE. The position of the RE maximum within the oxide layer also varied with the substrate composition. For all coatings {sup 18}O was found to have diffused through the oxide to the substrate-oxide interface during oxidation, the amount of oxide at this interface increasing with increasing time. The SIMS data confirm that for coated substrates there has been a change in oxide-growth mechanism to predominantly anion diffusion. The RE most probably concentrates at the oxide grain boundaries, generally as the binary oxide (RE)CrO{sub 3}. Cr{sup 3+} diffusion is impeded, while oxygen diffusion remains unaffected.

A new strategy, releasing nitric oxide (NO) and adsorbing nitrosamines simultaneously by zeolitic materials in the digestive system, is validated in this paper. Three types of moisture-saturated molecular sieves, HZSM-5 zeolite, mesoporous zeolite, and mesoporous silica MCM-41, are used as NO-delivery vessels in mimic gastric juice after modification of ?-aminopropyltriethoxysilane (APTES). APTES modification dramatically increased the capability of zeolite and mesoporous silica in NO release in acidic solution, because more NO can be adsorbed in the composite and stored in the form of nitrite. Some composites released the NO 10 times more than their parent materials, and synchronously captured the carcinogen nitrosamines in mimic gastric juice. The influences of APTES modification on the porous structure and surface state of zeolite and mesoporous silica were investigated by XRD, N(2) adsorption, and FTIR tests, through which the mesoporous zeolite is proven to be the optimal support. With this hierarchical material a controllable APTES modification is realized in which a lot of aminopropyl groups are grafted in mesopores while the zeolitic structure is maintained, so the resulting sample exhibits a high capability in releasing NO and adsorbing nitrosamines. This investigation provides a clue for elevating the efficiency of zeolites in the application of life science. PMID:21306723

Raman scattering of molecules adsorbed on the surface of TiO(2) nanoparticles was investigated. We find strong enhancement of Raman scattering in hybrid composites that exhibit charge transfer absorption with TiO(2) nanoparticles. An enhancement factor up to approximately 10(3) was observed in the solutions containing TiO(2) nanoparticles and biomolecules, including the important class of neurotransmitters such as dopamine and dopac (3,4-dihydroxy-phenylacetic acid). Only selected vibrations are enhanced, indicating molecular specificity due to distinct binding and orientation of the biomolecules coupled to the TiO(2) surface. All enhanced modes are associated with the asymmetric vibrations of attached molecules that lower the symmetry of the charge transfer complex. The intensity and the energy of selected vibrations are dependent on the size and shape of nanoparticle support. Moreover, we show that localization of the charge in quantized nanoparticles (2 nm), demonstrated as the blue shift of particle absorption, diminishes SERS enhancement. Importantly, the smallest concentration of adsorbed molecules shows the largest Raman enhancements suggesting the possibility for high sensitivity of this system in the detection of biomolecules that form a charge transfer complex with metal oxide nanoparticles. The wavelength-dependent properties of a hybrid composite suggest a Raman resonant state. Adsorbed molecules that do not show a charge transfer complex show weak enhancements probably due to the dielectric cavity effect. PMID:19364105

Adsorption of Cr (VI) from aqueous solution was studied using a continuous fixed bed column which is packed with a new micro-porous composite particle developed in this study. This composite particle is composed of silica porous particle in which acrylamide is polymerized within the pore regions of the silica particles. The composite particle was supposed to maintain the mechanical properties of polyacrylamide as efficient absorbent to serve appropriately in the continuous processes. In order to enhance the adsorption capacity of the composite particle, it was modified with ethylenediamine. Scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FT-IR) and thermogravimetry analysis (TGA) was applied to characterize the adsorbent. It was shown that polyacrylamide itsel...

The composites of polypyrrole/manganese dioxide/polypropylene fibrous films (PPy/MnO2/PPF) have been prepared in situ through chemical oxidation polymerization by using the mixture of FeCl3.6H2O and MnO2 adsorbed on PPF as oxidant in the atmosphere of pyrrole vapor at room temperature. The morphologies and structures of the composites are investigated by using scanning electron microscope and X-ray diffraction spectroscopy. The properties of the capacitor cells assembled by the composites of PPy/MnO2/PPF are evaluated by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy methods. The results reveal that the morphologies, conductivities and capacitance performance of the composites are influenced strongly by the content of MnO2 in the solution of o...

This report presents a facile approach for the low-temperature synthesis of crystalline inorganic-oxide composite hollow spheres by employing the bulk controlled synthesis of inorganic-oxide nanocrystals with polymer spheres as templates. The sulfonated polystyrene gel layer can adsorb the target precursor and induce inorganic nanocrystals to grow on the template in situ. The crystalline phase and morphology of the composite shell is tunable. By simply adjusting the acidity of the titania sol, crystalline titania composite hollow spheres with tunable crystalline phases of anatase, rutile, or a mixture of both were achieved. The approach is general and has been extended to synthesize the representative perovskite oxide (barium and strontium titanate) composite hollow spheres. The traditiona...

Combustion of wood produces particulate matter (PM) emissions having the potential to induce respiratory tract diseases in humans. To date, however, few, if any, in vitro submerse exposure adverse effect studies characterized the actual particle characteristics within the culture medium. Indeed, the availability of particles and adsorbed toxic compounds in liquids may depend on particle characteristics, i.e. aggregation, size, composition, type (complex solids, salts, etc.) and thus affect toxicity. Using polystyrene nanoparticles as reference, the particle size distribution and aggregation status of wood furnace PM and quartz particles in standard cell culture medium and water was characterized. Characterization was carried out via scanning electron microscopy (SEM), light microscopy, dynamic light scattering (DLS), and laser diffraction. Moreover, the biological availability of particles and adsorbed polycyclic aromatic hydrocarbons was tested using an Ah-receptor reporter gene assay, which demonstrated that particle characterization and knowledge of toxin bioavailability prior to experimentation is key for understanding potential biological interactions. PMID:22562490

The present investigation highlights the effectiveness of surfactant modified chitosan bead for adsorption of Cu(II), Ni(II) and Zn(II) from aqueous solution. An ideal experimental model was developed using fractional factorial and central composite design (CCD) based on response surface methodology (RSM). Among the experimental parameters viz. pH, adsorbent dose, concentration of metal, agitation time and temperature the most effective influencing parameters and their interactions were identified by a fractional factorial design. The optimal conditions for the three effective parameters, thus identified, were found to be: adsorbent dose, 0.5gdm^-^3, temperature 313K for all the metals and pH, 5.4, 7.3 and 6.5 for Cu(II), Ni(II) and Zn(II) respectively from CCD. Analysis of variance (ANOVA...

Class ''F'' fly ash (FA), collected from the Central Heat and Power (CHP) Plant Brasov (Romania), with oxides composition SiO2/Al2O3 over 2.4 proved good adsorbent properties, and was further used for obtaining a new substrate with good adsorption capacity for heavy metals from multi-cation wastewater treatment. Firstly, the new adsorbent was characterized by AFM, XRD, DSC, FTIR and the surface energy was evaluated by contact angle measurements. The experimental data suggested that the new type of substrate is predominant crystalline with highly polar surface. The substrate was used for removing the Pb^2^+, Cd^2^+ and Zn^2^+ cations from mixed solutions. The results show high efficiency and selective adsorption the Pb^2^+ and Zn^2^+ cations. The optimized adsorption parameters were further...

To obtain accurate kinetics of adsorption pairs, dynamic tests of a composite adsorbent material (BaCl2 impregnated into a vermiculite matrix) and ammonia were performed on small samples under isothermal conditions and on a larger quantity in a laboratory scale adsorption system. The experimental results show that the size of the pressure swing plays an important role in the dynamics of adsorption pairs. This driving pressure difference affects the mass transfer of NH3 through the pores of adsorbent and therefore the performance of the complete adsorption system. A modified Linear Driving Force (LDF) model was used to fit the experimental results. It was shown that the model can predict the dynamics of both adsorption and desorption fairly well and can be used for the modelling of the adso...

Building materials emit volatile organic compounds (VOCs) indoors. They may also adsorb compounds so that an equilibrium with indoor air is reached. Samples were taken from the floor, walls, and ceiling of one room in a seven-year-old preschool building. They were placed in a small climate chamber for a period of 41 days. Samples from the air in the room and the chamber were analysed by gas chromatography and mass spectrometry, and about 60 compounds were identified. The composition of organics in the room air was reestablished in the chamber the first day. Since most of the compounds disappeared within 2 to 23 days, they are believed to have been adsorbed from the room air onto the material surfaces. During the last 10 days, 17 compounds remained at constant concentrations, implying that they are representative of the building material samples.

In this comparative study, the application of response surface methodology (RSM) in predicting and optimizing the amination conditions of activated carbon adsorbent toward CO2 adsorption was investigated. The adsorbents were prepared based on the central composite design (CCD) with three independent variables (i.e., amination temperature, amination time, and the use of pre-heat treated (HTA) or pre-oxidized (OXA) sorbent as the starting material), and the responses studied were CO2 adsorption and desorption capacity. Two quadratic models were developed to calculate the optimum amination conditions of activated carbon that provide a compromise between the studied responses (dependent variables). From the analysis of variance (ANOVA), the temperature of ammonia treatment was found to be the ...

In the present work the adsorption of aromatic compound, namely ?-naphthol (BN) by two granular activated carbons, one untreated and the other treated with HNO3 carried out under controlled conditions. The effects of experimental parameters on adsorption process such as pH, contact time and adsorbent dosage have been investigated. Experimental design methodology was applied to optimize the removal of ?-naphthol. The effect of various experimental parameters was investigated using five-level three-factorial central composite design (CCD). The relationship between the parameters and the response for model optimization was found and optimum conditions were obtained by CCD. In the optimum conditions obtained by response surface modeling, 100% BN was adsorbed on the carbons. Treatment with HNO3...

In the larger context of 2D polymeric structures, the morphologies obtained by adsorption and subsequent drying of charged, ABA type amphiphilic triblock copolymer of poly[2-(dimethylamino)ethyl metacrylate] (PDMAEMA) and poly(propylene oxide) (PPO) were investigated with atomic force microscopy and X-ray photoelectron spectroscopy as well as in situ adsorption analysis with quartz crystal microbalance with dissipation monitoring. Hydrophilic silica and hydrophobic polystyrene (PS) were used as substrates for adsorption. The structures emerging from the self-assembly of adsorbing polymer were profoundly influenced by composition of the aqueous solution and the choice of substrate. When adsorbed from dilute polymer solution where the concentration is so low that the polymer does not yet sho...

The amount of water adsorbed on different centers on the surface of oxalic acid alumina films is a function of the anodizing voltage. It is decreased with increasing the anodizing voltage from 20 up to 50 V, came up to maximum value at 20-30 V and slightly increased at voltages above 50 V. Water adsorption by oxide films formed at voltages below 50 V can be due to the negative surface charge that is present on the alumina surface. The negative surface charge disappears in the films formed at voltages higher than 50 V, and thus, the water is adsorbed on aluminum ions in a tetrahedral and octahedral environment. The correlation between anodizing conditions of aluminum in oxalic acid and the structure and composition of anodic alumina was established by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), thermogravimetric and differential thermal analyses (TG/DTA).

A novel layered double hydroxide containing lanthanum (Cu/Mg/Fe/La-LDH) has been synthesized and used for the removal of arsenate from aqueous solutions. The purpose of incorporation of La^3^+ into LDHs was tried to enhance the uptake efficiency of arsenate and broaden the application field of LDHs functional materials. Effects of various physico-chemical factors such as solution pH, adsorbent dosage, contact time and initial arsenate concentrations on the adsorption of arsenate onto Cu/Mg/Fe/La-LDH were investigated. Results showed that the removal efficiency of arsenate increased with the increment of the lanthanum content in Cu/Mg/Fe/La-LDH adsorbents, and the optimized lanthanum content was 20% of the total trivalent metals composition (Fe^3^+ and La^3^+). The adsorption isotherms can ...

A composite of Fe3O4 nanoparticles and the biopolymer chitosan, chemically crosslinked, was prepared as microspheres and used to adsorb copper ions, which were chosen as a model of contaminant metal in water.The adsorption of copper on the magnetic microspheres was studied in a batch process, with different aqueous solutions of Cu (II) at concentrations ranging from 40 to 1100 ppm.Kinetic and equilibrium aspects of the adsorption process were studied. The time-dependent Cu (II) adsorption data were well described by a pseudo-second-order kinetic model. It was found that the equilibrium data follow the Langmuir isotherm, with a maximum adsorption capacity of around 500 mg Cu/g chitosan.The used microspheres were removed and after desorption the material was able to be reused as an adsorbent.The prepared microspheres proved efficient in the removal of copper ions through an adsorption process whose kinetic and equilibrium characteristics were analyzed.

Molecular dynamics (MD) computer simulations were used to study the adsorption of inert gases (N[sub 2], Ar, Ne) onto glass surfaces. There were four types of surfaces used: silica, sodium trisilicate, sodium disilicate, and sodium aluminosilicate. Unlike the results seen previously in the deposition of metals onto these surfaces, it was found that the inert gas adsorbates had little or no effect on the substrate structure during the adsorption. However the structure of the glasses dramatically altered the adsorption behavior from point to point along the surface for all of the adsorbates. Nitrogen and argon were found to be unable to penetrate the glass surfaces. Individual neon atoms were able to penetrate all of the surfaces except for the sodium aluminosilicate. The reasons for the difference in adsorption behavior are discussed in terms of the compositional effects on the structure of the glasses. 24 refs., 8 figs., 4 tabs.

The possibility of applying activated carbon and polymeric sorbents poly(4-vinylpyridine), polytrimethylsilylpropyne (PTMSP), bromo-substituted PNMSP (Br-PNMSP), poly(N-methyl-4-vinylpyridinium iodide) for the sorption recovery of iodine from a 0.5 M solution of sodium chloride is studied. The dependence of iodine sorption on the pH of solution, the amount of adsorbent, and the duration of contact between the solution and adsorbent is studied. The highest sorption capacity (G = 616.78 mg/g) is attained by using poly(N-methyl-4-vinylpyridinium iodide) anionite with the addition of iodine to form complex triiodide ions. The dynamics of iodine adsorption on poly(4-vinylpyridine) is described by a kinetic model of pseudosecond order. The composition and structure of the iodine compounds sorbed...

Based on numerical simulations and experimental studies, we show that a composite material which consists of a sheet of graphene on a Au(111) surface exhibits both an excellent conductivity and the ability to stably adsorb biomolecules. If we use this material as a substrate, the signal-to-noise ratios can be greatly enhanced. The key to this unique property is that graphene can stably adsorb carbon-based rings, which are widely present in biomolecules, due to pi-stacking interactions while the substrate retains the excellent conductivity of gold. Remarkably, the signal-to-noise ratio is found to be so high that the signal is clearly distinguishable for different nucleobases when an ssDNA is placed on this graphene-on-Au(111) material. Our finding opens opportunities for a range of bio/nano-applications including single-DNA-molecule-based biodevices and biosensors, particularly, high-accuracy sequencing of DNA strands with repeating segments. PMID:20058291

Experimental and numerical investigations of gas sorption on coal, and the subsequent volumetric and permeability changes of the coal were conducted. The goals of the study were to investigate the magnitude of permeability change caused by gas sorption, and develop an algorithm to simulate numerically gas sorption and sorption-induced permeability change. The amount of gas sorption and the subsequent volumetric and permeability change of coal samples as a function of pore pressure and injection gas composition were measured in the laboratory. A constant effective confining pressure (difference between the confining pressure and pore pressure) was maintained in the process of the experiments; therefore, the role of effective stress on permeability was eliminated. Several gases, including pure CO2, pure N2, and binary mixtures of CO2 and N2 of various compositions were used as the injection gas. The coal sample was first allowed to adsorb an injection gas fully at a particular pressure. The total amount (moles) of adsorption was calculated based on a volumetric method. After adsorption equilibrium was reached, gas samples were taken from the equilibrium gaseous phase and analyzed afterwards. The composition of the gaseous phase prior to and after the adsorption was used to calculate the composition of the adsorbed phase based on material balance. Permeability of the sample was then measured by flowing the injection gas through the core at varying pressure gradient or varying flow rate, and an average permeability was obtained based on Darcy's law for compressible systems. The change of the total volume of the core was monitored and recorded in the whole process of the experiment. Volumetric strain was thereby calculated. Experimental results showed that the greater the pressure the greater the amount of adsorption for all tested gases. At the same pressure, the amount of adsorption was greater for CO2 than N2. For the binary mixtures, the greater the fraction of CO 2 in the injection gas, the greater the amount of total adsorption. Volumetric strain followed the same trend as the amount of adsorption with pressure and injection gas composition. Permeability showed opposite behaviors, decreasing with the increase of pressure and the percentage of CO2 in the injection gas. The experimental adsorption, volumetric strain, and permeability data were analyzed to investigate the numerical correlations between gas sorption, sorption-induced volumetric strain and permeability, and pressure and injection gas composition. The relationship between the amount of adsorption and pressure for pure gases (CO2 and N2) were readily represented by parametric isotherm models, such as Langmuir and the N-layer BET equations. Modeling efforts of multicomponent adsorption included predicting amount of adsorption and adsorbed phase composition based on the extended Langmuir equations and the ideal adsorbed solution model. Activity coefficients of the components in the adsorbed phase were computed based on the real adsorbed solution model and the ABC excess Gibbs free energy model. Algorithms for modeling the CO 2/N2-Coal system were developed, and the constraints and strength of each model were discussed. The experimental volumetric strain was found to be linearly proportional to the total amount of adsorption and independent of the injection gas composition. The permeability reduction could not be readily correlated by the models in the literature unless the change of other coal properties (bulk modulus, axial constrained modulus, etc.) due to gas sorption was incorporated. The sorption, volumetric strain, and permeability data collected in this study can be used for comparison by other researchers conducting similar studies. The algorithms of sorption modeling and the correlations developed in this study are readily incorporated into the simulation of enhanced coalbed methane recovery and CO2 sequestration in coalbeds. (Abstract shortened by UMI.)

A hydrodynamic model of the upper part of the Techa river was developed on the basis of the river valley geometry as well as data of hydrological conditions and of the granulometric composition of bottom sediments. The model describes the transport of radioactivity by suspended sediments with different granulometric compositions (clay, silt) in the early 1950s. It includes the stirring-up of bottom sediments and the precipitation of suspended sediments as a function of water discharge rate and water level in the investigated part of the river. The results allow to specify the development of the river system contamination as a result of inflow of suspended sediments contaminated with radionuclides. In the period of liquid radioactive waste (LRW) discharges, the water of the Techa river contained a large fraction of finely dispersed particles of less than 5 micro m diameter. At the site of LRW discharge 80% of the discharged activity was adsorbed to these particles. Depending on the water flow, 40-80% of the suspensions precipitated at the bottom of subsequent sedimentation reservoirs. A total of about 1.6 MCi adsorbed to the suspended particles entered the open hydrographic system of the Techa river. The conclusion that the largest part of the activity was adsorbed on the suspended particles contradicts the assumption in the Techa river dosimetry system, TRDS-2000, that most of the released activity entered the Techa river in soluble form. For a correct reconstruction of the doses received by the Techa river population it is, therefore, essential to consider hydrodynamic models that take into account the transport of radionuclides adsorbed on the suspended particles. PMID:14714191

SOLIDIFIED Ni-AI-Mo ANDCOMPARATIVEEFFECTSOFALLOY ... cyclic furance tests Ni-16.4Cr-5.1Al-O.151ZrO2_7.8Y203on y/y' - _ substratehad a life of 246 hours, .... uniform oxide coating thickness on specimens tested in the torch rig. This ...

A small window was built into one wall of the aluminum case to ...... Experienced operators are cap- able of removing ...... measurements of the ability of the oxide coating to retain ...... of a tape roll, which often occurs spontaneously as the pile ...

Simple and convenient technique has been found for extending transmittance measurement capability of conventional magnesium oxide coated integrating sphere system at low (near ultraviolet) wavelengths. Technique can be used to determine effect of contaminants on window materials and can also be used for measurements on thermal control coatings and telescope mirrors.

In this article, the titanium dioxide (TiO2) layer on titanium dioxide coated mica (TiO2-mica) particles is reduced into a very dark blue titanium lower oxide coating for the synthesis of a colored titanium oxide coated mica. The reduced version that shows color by interference is disadvantages, however, in that light is absorbed by the titanium lower oxide coating and that the refraction factor is lower than that of a TiO2 coating. Under such circumstances, electroless plating is employed for manufacturing a metal thin film that is effective in absorbing transmitted light and yet high in reflection capability. In this report, the structure and color tone of the TiO2-mica produced by electroless plating are compared with those of the titanium lower oxide coated mica. An Ni coating is provided by electroless plating on an interference color showing TiO2-mica, and a colored Ni-TiO2-mica, capable of showing color only by interference of TiO2 without the help of pigments is developed. It is found after the investigation of its structure that the surface of the TiO2-mica is coated by particles not larger than 5nm in diameter of amorphous Ni or its oxide. The color showing feature of the Ni-TiO2-mica is ascribed to the absorption by the Ni particles of the transmitted light. 3 refs., 10 figs.

refractory oxide coatings such as alumina, zirconia, yttria, mullite, cordierite, etc., on SiC [8 ... annealed in air at 1300°C for 100h, prior to the environmental exposure. ... furnace. Each thermal cycle consisted of 2h at temperature, rapid cooling ...

Two kinds of Al/Zr (Al(1%wtSi)/Zr and Al(Pure)/Zr) multilayers for extreme ultraviolet (EUV) optics were deposited on fluorine doped tin oxide coated glass by using direct-current magnetron sputtering technology. The comparison of the two systems shows that the Al(1%wtSi)/Zr multilayers have the low...

indicate that thin film metal oxide coatings are very effective in protecting .... on optical measurements during RF plasma ashing rather than weight loss of the ... disks 2.54 cm in diameter and 0.121 mm thick which were mounted in aluminum ...

The addition of 2-ethyl-1-hexanol to an organometallic titanium compound dissolved in a diluent and optionally containing a lower aliphatic alcohol spreading modifier, produces a solution that can be sprayed onto a substrate and cured to form an antireflection titanium oxide coating having a refractive index of from about 2.0 to 2.2.

Stainless steel based dye solar cells have been upscaled from small, laboratory size test cells of 0.32 cm2 active area to 6 cm x 6 cm "mini-modules" with active areas ca. 15 cm2. Stainless steel works as the photoelectrode substrate whilst the counter electrode is prepared on indium-doped tin oxide coated polyethyleneterephtalate or polyethylenenaphtalate plastic foil (fluorine-doped tin oxide coated glass as a reference). Additional current collector structures were deposited on the counter electrode substrate with inkjet-printing of silver nanoparticle ink in order to reduce the lateral resistance of the plastic foil. Flexible substrates enable roll-to-roll type industrial manufacturing of the cells and the steel's superior conductivity compared to the typical substrate materials such as glass and plastic makes it possible to prepare even substantially larger modules. The best efficiencies obtained this far with the "mini-module" using a stainless steel photoelectrode are 2.5% with a platinum-sputtered indium-doped tin oxide coated polyethyleneterephtalate counter electrode and 3.4% with a thermally platinized fluorine-doped tin oxide coated glass counter electrode. These efficiencies are on the same level than those measured with small cells prepared with similar methods and materials (3.4%-4.7%, depending on configuration, which are amongst the highest reported for this kind of a dye solar cell). Replacing expensive conducting glass with steel and plastic foils as the substrate materials leads also to economical savings in the cell production. PMID:20352759

A modified dip coating process was developed to deposit transparent conducting sol-gel SnO2:Sb (ATO, antimony doped tin oxide) coatings inside tubes and cavities in optical quality. The necessity for this improvement arises from the fact that the conventional dip coating process applied to tubes res...

During this SBIR Phase II project, we have successfully established high quality SnO{sub 2}(F) based transparent conductive oxide coatings by atmospheric pressure chemical vapor deposition technique and built a large area prototype APCVD deposition system which incorporates innovative design features. This work enhances US photovoltaic research capability and other thin film oxide related research capability.

A prototype amperometric immunosensor was evaluated based on the adsorption of antibodies onto perpendicularly oriented assemblies of single wall carbon nanotubes called SWNT forests. The forests were self-assembled from oxidatively shortened SWNTs onto Nafion/iron oxide coated pyrolytic graphite el...

Previous work focused on the production of carbon fiber composites and subsequently activating them to induce adsorbent properties. One problem related to this approach is the difficulty of uniformly activating large composites. In order to overcome this problem, composites have been made from pre-activated fibers. The loss of surface area upon forming the composites after activation of the fibers was investigated. The electrical resistivity and strength of these composites were compared to those made by activation after forming. It was found that the surface area is reduced by about 35% by forming the composite from pre-activated fibers. However, the properties of the activated sample are very uniform: the variation in surface area is less than {+-}0.5%. So, although the surface area is somewhat reduced, it is believed that making composites from pre-activated fibers could be useful in applications where the BET surface area is not required to be very high. The strength of the composites produced from pre-activated fibers is lower than for composites activated after forming when the carbon burnoff is below 45%. For higher burnoffs, the strength of composites made with pre-activated fibers is as good or better. In both cases, there is a dramatic decrease in strength when the fiber:binder ratio is reduced below 4:1. The electrical resistivity is slightly higher for composites made from pre-activated fibers than for composites that are activated after forming, other parameters being constant (P-200 fibers, similar carbon burnoffs). For both types of composite the resistivity was also found to increase with carbon burnoff. This is attributed to breakage of the fiber causing shorter conductive paths. The electrical resistivity also increases when the binder content is lowered, which suggests that there are fewer solid contact points between the fibers.

The effects of pH of the buffer solution and the composition of the hydrogel system on the bovine serum albumin (BSA) adsorption capacity of chitosan (CS)-polyvinyl pyrrolidone (PVP) (CSPVP) hydrogels and release of BSA were investigated. Poly-electrolyte CSPVP hydrogels with different compositions were prepared by irradiating CS/PVP/water mixtures with {gamma}-rays at ambient temperature. The adsorption capacity of hydrogels was found to increase from 0 to 350 mg BSA/g dry gel, by changing external stimuli and hydrogel composition. The adsorption of BSA within CSPVP hydrogels increased with increase in CS content in the hydrogels. When the irradiation doses of hydrogel increased, the adsorption of BSA decreased. The maximum adsorption of BSA was observed at pH 5. A significant amount of the adsorbed BSA (up to 95%) was eluted in the phosphate medium containing 0.1 M NaCl at pH 7.4.

A new type consolidated composite activated carbon (AC) was developed with a host matrix of expanded natural graphite treated with sulfuric acid (ENG-TSA). Samples with different density, different grain size of AC, and different proportion of AC were produced and thermo-physical properties were evaluated. Results show that the highest effective thermal conductivity and thermal diffusivity of consolidated composite AC were 34.2Wm-1K-1 and 3.89x10-5m2s-1, which were 150 times and 72 times higher, respectively, than ordinary granular AC. The permeability of adsorbents ranged between 1.24x10-14 and 7.81x10-10m2 while the density ranged between 215 and 448kgm-3. The adsorption performance for composite AC and granular AC were evaluated by fitting experimental data with the equilibrium Dubinin-...

TiO2/Ca-montmorillonite composites were prepared by wet grinding in an agate mill. Positively charged TiO2 nanoparticles are bound to the surface of the negatively charged montmorillonite layers via heterocoagulation; the clay mineral is used as adsorbent and support for the photooxidation process. Aquatic solution of 0.5mM phenol was degraded by irradiation with UV-VIS light (lambda=250-440 and 540-590 nm) in suspensions of TiO2-clay composites and significant photodegradation was observed at 40-60% TiO2/Ca-montmorillonite compositions. Synergistic effect was detected at solid/liquid interface for degradation of phenol and at solid/gas interface in the recycling flow reactors for photooxidation of ethanol and toluene vapors. PMID:17698167

In difference to compact objects of a similar size, toroidal structures have some distinguishing properties that originate from their open inner cavity and closed circuit. Here, a general facile methodology is developed to prepare composite rings with varied compositions on a large scale by using core-shell toroids assembled from tri-block copolymers of poly(4-vinyl pyridine) (PVP)/polystyrene (PS)/PVP. Taking advantage of the complexation ability of the PVP shell, varied components that range from polymers, inorganic materials, metals and their compounds, as well as pre-formed nanoparticles are introduced to the toroidal structures to form composite nanostructures. Metal ions can be adsorbed by PVP through complexation. After in situ reduction, a large number of metal-based functional mat...

The main objective of the present contribution is to analyze the effect of composition, coverage and Te doping in the surface composition and catalytic behavior of supported-nanoscaled MoVNb(Te)O catalysts. Different spectroscopy techniques combine to afford such objective. The composition of the surface species has been studied by Raman and UV-Vis spectroscopies, whereas it has been performed several pyridine adsorption experiments to quantify the number of acid sites on the surface of catalysts. The nature of reaction intermediates and the capability of the samples to adsorb them have been studied by FTIR spectroscopy combined with the adsorption of propene. The results have shown that tellurium induces several changes in the structure and catalytic properties of MoVNb catalytic material...

Mesoporous carbon nitride (MCN) and carbon nitride-carbon (MCN/C) composites with a partly graphitized structure are synthesized by using mesoporous silica SBA-15 as a hard template and ethylenediamine and carbon tetrachloride as precursors, possessing uniform mesopore size of 6.3nm, high surface area of 278-338m2/g, and high nitrogen content of 20.5-24.9% with abundant basic sites. The synthesized MCN and MCN/C composites are used as adsorbents for CO2 capture, showing high adsorption capacity and good reusability. The presence of carbon coating layer in MCN/C composites introduced more micropores, which favored the capture of CO2, exhibiting high CO2 capture capacity of 3.05mmol/g at 0degreeC and 2.35mmol/g at 25degreeC and 760mmHg, with good CO2/N2 selectivity and excellent regeneration...

In this study, we report a facilely hydrothermal process for synthesizing SnO2 nanorods-graphene (SnO2 nanorods-GR) composite using graphite oxide and SnCl4 as raw materials. The SnO2 nanorods-GR composite was characterized by X-ray diffraction, electron microscopy, Xray photoelectron spectroscopy, and thermogravimetric analysis. Compared to commercial TiO2 nanoparticles P25 and neat SnO2 nanorods, the SnO2 nanorods-GR composite exhibits higher photocatalytic activity under UV light irradiation. The mechanism of its high photocatalytic activity is mainly ascribed to the synergy effect between SnO2 and graphene, in which graphene acts as an adsorbent and electron acceptor due to its large structure of pi-pi conjugation from sp2 hybrid carbon atoms. The results demonstrated in this study provide a promising way to enhance the photocatalytic activity by compounding semiconductive nanocrystals with graphene. PMID:23035415