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1

Development and evaluation of Mn oxide-coated composite adsorbent for the removal and recovery of heavy metals from coal processing wastewater. Final report, December 1995  

Energy Technology Data Exchange (ETDEWEB)

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.

Fan, Huan Jung; Anderson, P.R.

1995-12-31

2

Luminescence of europium-doped anode oxide-coated films on the multilayer titanium-tantalum compositions  

International Nuclear Information System (INIS)

Luminescence of europium in anode oxide-coated films on thin-film titanium-tantalum compositions and process of their anode oxidation by means of chronovoltamperemetry at different order of metallic layers and annealing temperatures were investigations. Correlation of luminescence spectra and diagram of chronovoltamperemetry was shown. Luminescence spectra of samples are characterized by a few types of luminescent center corresponding to Eu3+ and the base

3

Implementation of the adsorbent iron-oxide-coated natural rock (IOCNR) on synthetic As(III) and on real arsenic-bearing sample with filter  

Science.gov (United States)

This study examined the As(III) adsorption efficiency on an iron-oxide based adsorbent, iron-oxide-coated natural rock (IONR), and proposes an in situ two-step mechanism, oxidation of As(III) to As(V) and its subsequent adsorption on IOCNR. In the batch study, within 6 h of contact time and at a dose of 13 g L-1, ?98.5% As(III) (declined to ?0.01 mg L-1) removal was achieved from the water medium, when the initial concentration was 0.6 mg L-1 at room temperature. The As(III) adsorptive capacity of IOCNR was calculated using the Langmuir isotherm 1.647 mg g-1. The effects of various parameters for As(III) adsorption, including contact time, dose, pH, initial As(III) concentrations, the presence of common cations and anions, along with some organic contaminants, were evaluated. Spontaneity and favorable adsorption of As(III) on IOCNR were evidenced from the negative Gibbs free energy changes and dimensionless equilibrium parameter. As(III) removal efficiency of the exhausted and NaOH-regenerated IOCNR decreased in the second-cycle operation. As(III) removal efficiency of IOCNR was comparable to that of the commercially available patented adsorbent LEWATIT FO36. The adsorptive behavior of IOCNR from real arsenic-bearing sample was also evaluated. Finally, small-scale household filter “SHITAL-2013” was designed and the effluent water quality was analyzed.

Maji, Sanjoy Kumar; Kao, Yu-Hsuan; Liao, Pei-Yu; Lin, Yi-Jie; Liu, Chen-Wuing

2013-11-01

4

Simple and Efficient Synthesis of Iron Oxide-Coated Silica Gel Adsorbents for Arsenic Removal: Adsorption Isotherms and Kinetic Study  

International Nuclear Information System (INIS)

Iron oxide (ferrihydrite, hematite, and magnetite) coated silica gels were prepared using a low-cost, easily-scalable and straightforward method as the adsorbent material for arsenic removal application. Adsorption of the anionic form of arsenic oxyacids, arsenite (AsO2-) and arsenate (AsO4-3), onto hematite coated silica gel was fitted against non-linear 3-parameter-model Sips isotherm and 2-parameter-model Langmuir and Freundlich isotherm. Adsorption kinetics of arsenic could be well described by pseudo-second-order kinetic model and value of adsorption energy derived from non-linear Dubinin-Radushkevich isotherm suggests chemical adsorption. Although arsenic adsorption process was not affected by the presence of sulfate, chloride, and nitrate anions, as expected, bicarbonate and silicate gave moderate negative effects while the presence of phosphate anions significantly inhibited adsorption process of both arsenite and arsenate. When the actual efficiency to remove arsenic was tested against 1 L of artificial arsenic-contaminated groundwater (0.6 mg/L) in the presence competing anions, the reasonable amount (20 g) of hematite coated silica gel could reduce arsenic concentration to below the WHO permissible safety limit of drinking water of 10 ?g/L without adjusting pH and temperature, which would be highly advantageous for practical field application

5

Extraction of uranium from seawater by the fibrous composite adsorbent  

International Nuclear Information System (INIS)

The fibrous composite adsorbents consisting of hydrous titanium oxide and activated carbon were prepared with hydrophilic polyacrylonitrile system polymer as a binder under various conditions, and the adsorptive property of the fibrous composite adsorbents for uranium from seawater was examined. The fibrous composite adsorbents which spun under high pressure (10 kg/cm2) was the finest having the largest pore volume. In addition, the amount of uranium adsorbed of the fibrous adsorbent was the largest. The rate of uranium adsorption by the fibrous adsorbent was the same as the rate of uranium adsorption by the powdery adsorbent. The excellent fibrous adsorbent adsorbed 0.23 mg U/g adsorbent for 10 d and 0.65 mg U/g adsorbent for 100 d. The rate of uranium desorption from the fibrous adsorbent by alkali carbonate solution was large, and the uranium in the fibrous adsorbent desorbed 75 % for 8 h and about 100 % for 24 h. (author)

6

The influences of microdischarge types and silicate on the morphologies and phase compositions of plasma electrolytic oxidation coatings on Zircaloy-2  

International Nuclear Information System (INIS)

Highlights: ? ZrO2 coatings are grown on Zircaloy-2 by plasma electrolytic oxidation. ? Characteristic solidification structures are formed on the coatings. ? This structure has not been found on the PEO coatings of other valve metals. ? Very low thermal conductivity of zirconia helps the formation of the structure. - Abstract: Plasma electrolytic oxidation coatings were formed in alkaline silicate electrolyte on Zircaloy-2. The evolution of the types of discharges, the microstructures, phase compositions and the corrosion resistance of the coatings were studied by real time imaging, SEM, XRD, and electrochemical tests. Characteristic solidification structures were revealed in the PEO coatings, the formation of the solidification structures is related to the long lasting discharges during the PEO process and the very low thermal conductivity of zirconium oxide. Thermal effect in the coatings and silicate content in the electrolyte affect the phase compositions of the coatings.

7

Isothermal composite adsorbent. Part I: Thermal characterisation  

International Nuclear Information System (INIS)

Adsorption and desorption are respectively exo and endothermic phenomena leading to significant temperature changes in adsorption columns. Enhanced efficiency of a sorption process could be obtained under isothermal conditions, either for gas storage, purification or separation applications. The heat transfer within the adsorbent beds can be managed in situ, using thermal energy storage material: a phase change materials (PCM) for example. The thermal behaviour of a mixture of activated carbon and PCM during CO2 adsorption has been studied. The thermal characteristics of the involved materials have been determined and experiments carried out to highlight the positive effect of the PCM to reduce the CO2 adsorption heat effects on an activated carbon bed. Calorimetry was the technique used for all the thermal characterisations. It appears that the heat effects induced by CO2 adsorption are reduced by the presence of the PCM together with the adsorbent. The endothermic effect of fusion balances the heat effect of adsorption and significantly reduces the temperature changes

8

Adsorption Characterization of Strontium on PAN/Zeolite Composite Adsorbent  

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This work reports the adsorption of strontium from aqueous solutions onto PAN/zeolite composite. The strontium adsorption on the composite adsorbent was studied as a function of initial strontium concentration, pH of the solution, contact time and temperature. Adsorption isotherms like Langmuir, Freundlich,Dubinin–Radushkevich (D–R) and Temkin were used to analyze the equilibrium data at the different concentrations.Adsorption process well fitted to Temkin isotherm model. Thermodynamic pa...

Sabriye Yusan; Sema Erenturk

2011-01-01

9

Desorption of uranium from titanium-activated carbon composite adsorbent  

International Nuclear Information System (INIS)

An investigation was made on the desorption of uranium from titanium-activated carbon composite adsorbent with mixed eluent of Na2CO3 and NaHCO3. The rate of desorption of uranium from the adsorbent in the batch process depended on the composition of eluent and temperature. The rate of desorption showed an increase as the ratio of NaHCO3 to Na2CO3 was increased or the temperature was raised. In the column process with the mixed eluent of 0.5 N Na2CO3 and 0.5N NaHCO3 at an ordinary temperature, the rate of desorption of uranium did n ot vary in the range of adsorbent/eluent ratio below 20% and initial uranium concentration of eluent less than 15 ppm. Under these conditions, the eluent was found to be re-usable without a decrease in the rate of desorption. From these results, the application of multistage desorption process was discussed. The dissolution of titanium from adsorbent was less than 0.15%. The adsorbet, which was regenerated by washing with 0.1 N HCl after desorption, was found to be re-usable. (author)

10

Uranium extraction from sea water with composite adsorbents, (1)  

International Nuclear Information System (INIS)

For the purpose of development of adsorbents for the extraction of uranium from sea water, titanium based composite hydrous oxides were synthesized and their uranium adsorption capacities were investigated. They are composite hydrous oxides of Ti(IV)-Al(III), Ti(IV)-Fe(III), Ti(IV)-Ce(III), Ti(IV)-Cr(III), Ti(IV)-La(III), Ti(IV)-Si(IV), Ti(IV)-Zr(IV) and Ti(IV)-Sn(IV), prepared as precipitation products by addition of sodium hydroxide solution to the mixed solution of titanium tetrachloride and acidic solution of other metal. Adsorption experiments were carried by batch method using sea water in which slight amount of uranyl chloride was added. The initial uranium concentration was 10.1 ?g/l. The composite hydrous Ti(IV)-Fe(III) oxide was found to give the largest uranium adsorption capacity among the composite hydrous oxides and its uranium adsorption capacity per gram of titanium in adsorbent was about twice larger than that of hydrous Ti(IV) oxide alone. Uranium adsorption capacity of composite hydrous Ti(IV)-Al(III) oxide increases with the temperature of precipitation process. The composite hydrous Ti(IV)-Fe(III) oxide shows its maximum uranium adsorption capacity when it was prepared from pH 5 and 7 at 700C. It was found that the composite adsorbent, hydrous Ti(IV)-Fe(III) oxide, had its large uranium adsorption capacity when its mean pore radius was between 20 and 33 A, and its specific surface area was between 250 and 325 m2/g. (author)en 250 and 325 m2/g. (author)

11

Adsorption Characterization of Strontium on PAN/Zeolite Composite Adsorbent  

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Full Text Available This work reports the adsorption of strontium from aqueous solutions onto PAN/zeolite composite. The strontium adsorption on the composite adsorbent was studied as a function of initial strontium concentration, pH of the solution, contact time and temperature. Adsorption isotherms like Langmuir, Freundlich,Dubinin–Radushkevich (D–R and Temkin were used to analyze the equilibrium data at the different concentrations.Adsorption process well fitted to Temkin isotherm model. Thermodynamic parameters such as the changes in enthalpy, entropy and Gibbs’ free energy were determined, showing adsorption to be an exothermic and spontaneous process.

Sabriye Yusan

2011-04-01

12

Oxide coating development  

Energy Technology Data Exchange (ETDEWEB)

Monolithic SiC heat exchangers and fiber-reinforced SiC-matrix composite heat exchangers and filters are susceptible to corrosion by alkali metals at elevated temperatures. Protective coatings are currently being developed to isolate the SiC materials from the corrodants. Unfortunately, these coatings typically crack and spall when applied to SiC substrates. The purpose of this task is to determine the feasibility of using a compliant material between the protective coating and the substrate. The low-modulus compliant layer could absorb stresses and eliminate cracking and spalling of the protective coatings.

Stinton, D.P.

1995-06-01

13

Characterization of oxide coatings formed on tantalum by plasma electrolytic oxidation in 12-tungstosilicic acid  

International Nuclear Information System (INIS)

Oxide coatings were formed on tantalum by plasma electrolytic oxidation (PEO) process in 12-tungstosilicic acid. The PEO process can be divided into three stages with respect to change of the voltage-time response. The contribution of electron current density in total current density during anodization results in the transformation of the slope of voltage-time curve. The surface morphology, chemical and phase composition of oxide coatings were investigated by AFM, SEM-EDX, XRD and Raman spectroscopy. Oxide coating morphology is strongly dependent of PEO time. The elemental components of PEO coatings are Ta, O, Si and W. The oxide coatings are partly crystallized and mainly composed of WO3, Ta2O5 and SiO2. Raman spectroscopy showed that the outer layer of oxide coatings formed during the PEO process is silicate tungsten bronze.

14

Evaluation of oxide-coated iridium-rhenium chambers  

Science.gov (United States)

Iridium-coated rhenium (Ir-Re) provides long life operation of radiation-cooled rockets at temperatures up to 2200 C. Ceramic oxide coatings could be used to increase Ir-Re rocket lifetimes and allow operation in highly oxidizing environments. Ceramic oxide coatings promise to serve as both thermal and diffusion barriers for the iridium layer. Seven ceramic oxide-coated Ir-Re, 22-N rocket chambers were tested with gaseous hydrogen/gaseous oxygen (GHz/G02) propellants. Five chambers had thick (over 10 mils), monolithic coatings of either hafnia (HfO2) or zirconia (ZrO2). Two chambers had coatings with thicknesses less than 5 mils. One of these chambers had a thin-walled coating of ZrO2 infiltrated with sol gel HfO2. The other chamber had a coating composed of an Ir-oxide composite. The purpose of this test program was to assess the ability of the oxide coatings to withstand the thermal shock of combustion initiation, adhere under repeated thermal cycling, and operate in aggressively oxidizing environments. All of the coatings survived the thermal shock of combustion and demonstrated operation at mixture ratios up to 11. Testing the Ir-oxide composite-coated chamber included over 29 min at mixture ratio 16. The thicker walled coatings provided the larger temperature drops across the oxide layer (up to 570 C), but were susceptible to macrocracking and eventual chipping at a stress concentrator. The cracks apparently resealed during firing, under compression of the oxide layer. The thinner walled coatings did not experience the macrocracking and chipping of the chambers that was seen with the thick, monolithic coatings. However, burn-throughs in the throat region did occur in both of the thin-walled chambers at mixture ratios well above stoichiometric. The burn-throughs were probably the result of oxygen diffusion through the oxide coating that allowed the underlying Ir and Re layers to be oxidized. The results of this test program indicated that the thin-walled oxide coatings are better suited for repeated thermal cycling than the thick-walled coating, while thicker coatings may be required for operation in aggressively oxidizing environments.

Reed, Brian D.

1994-01-01

15

Effective thermal conductivity of expanded graphite-CaCl2 composite adsorbent for chemical adsorption chillers  

International Nuclear Information System (INIS)

This paper presents experimental data on the thermal conductivity for three types of adsorbent, namely, pure CaCl2 powder, simple composite adsorbent and consolidated composite adsorbent. The thermal conductivities were measured by the 'hot wire method' at a fixed pressure and temperature under an ammonia atmosphere. Effective thermal conductivities of the expanded graphite-CaCl2 . nNH3 (n = 2, 4, 8) consolidated composite adsorbent are in the range of 7.05-9.2 W m-1 K-1, which are significant higher values than those of the powders bed of 0.3-0.4 W m-1 K-1. The obtained results show that the composite adsorbent thermal conductivity ? has a strong dependence on the bulk density, the weight fraction of expanded graphite and the ammoniated state of CaCl2

16

The preparation of composite fiber adsorbents for separation of uranium from seawater by spinning(1)  

International Nuclear Information System (INIS)

Amidoximated composite fiber adsorbents were prepared for separation of uranium from seawater and characterized by various instrumental techniques, such as IR spectroscopy, CHN elemental analyzer and SEM. The swelling ratios and yields of the AN-TEGMA and AN-TEGMA-DVB copolymers were decreased with an increase in crosslinking agents, such as DVB and TEGMA composition. The yield of 85-92% and 82-88% of AN-TEGMA and AN-TEGMA-DVB copolymers respectively were found. The porosity was also decreased with increase in crosslinking compositions, and it was found that the AN-TEGMA-DVB porosity copolymers were smaller than the value of AN-TEGMA copolymer. We investigated that the adsorbent with the composite fiber adsorbents were well dispersed on the surface of its by SEM. The optimum contents of containing adsorbent in the copolymer was 40 weight percent. The capacity of uranyl ion through the composite fiber adsorbent containing the amidoxime group was maximized a pH level of 8. Also, it was found that the synthesized composite fiber adsorbent was good material, due to a pH level of 8.3 of seawater, for separation of uranyl ion from seawater. (author)

17

AMMONIA AND COD REMOVAL FROM SYNTHETIC LEACHATE USING RICE HUSK COMPOSITE ADSORBENT  

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Full Text Available Ammonia and chemical oxygen demand (COD were the most two problematic parameters in the landfill leachate. In this study, a new composite adsorbent derived from rice husk ash waste is evaluated with respect to its ability to remove these contaminants from synthetic leachate. Results indicate that the new composite adsorbent is able to adsorb both ammonia and COD. It has a higher adsorption capacity for ammonia (Q = 2.2578 mg/g and an almost equal adsorption capacity for COD (Q = 2.8893 when compared with commercially activated carbon. The adsorption kinetics of this new product for ammonia and COD were primarily represented by the pseudo second-order mechanism. The overall adsorption rate of the ammonia and COD adsorption processes appears to be determined by chemisorption process. The regenerated composite adsorbent indicated higher adsorption capacities of ammonia and COD, i.e. 12.9366 mg/g and 3.1162 mg/g, respectively.

Azhar Abdul Halim

2011-06-01

18

In situ toughened SiC ceramics with Al-B-C additions and oxide-coated SiC platelet/SiC composites  

Energy Technology Data Exchange (ETDEWEB)

This work aimed at fabrication and characterization of high toughness SiC ceramics through the applications of in situ toughening and SiC platelet reinforcement. The processing-microstructure-property relations of hot pressed SiC with Al, B, and C additions (designated as ABC-SiC) were investigated. Through a liquid phase sintering mechanism, dense SiC was obtained by hot pressing at a temperature as low as 1,700 C with 3 wt% Al, 0.6 wt% B, and 2 wt% C additions. These sintering aids also enhanced the {beta}-to-{alpha} (3C-to-4H) phase transformation, which promoted SiC grains to grow into plate-like shapes. Under optimal processing conditions, the microstructure exhibited high-aspect-ratio plate-shaped grains with a thin (< 1 nm) Al-containing amorphous grain boundary film. The mechanical properties of the toughened SiC and the composites were evaluated in comparison with a commercial Hexoloy SiC under identical test conditions. The C-curve behavior was examined using the strength-indentation load relationship and compared with that directly measured using precracked compact tension specimens. The in situ toughened ABC-SiC exhibited much improved flaw tolerance and a significantly rising R-curve behavior. A steady-state toughness in excess of 9 MPam{sup 1/2} was recorded for the ABC-SiC in comparison to a single valued toughness below 3 MPam{sup 1/2} for the Hexoloy. Toughening in the ABC-SiC was mainly attributed to grain bridging and subsequent pullout of the plate-shaped grains. The high toughness ABC-SiC exhibited a bend strength of 650 MPa with a Weibull modulus of 19; in comparison, the commercial SiC showed a bend strength of 400 MPa with a Weibull modulus of 6. Higher fracture toughness was also achieved by the reinforcement of SiC platelets, encapsulated with alumina, yttria, or silica, in a SiC matrix.

Cao, J. [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering]|[Lawrence Berkeley National Lab., CA (United States). Materials Sciences Div.

1996-12-01

19

Laser reflection from oxide-coated aluminum  

Science.gov (United States)

The theory of reflection from an oxide-coated metal is combined with experimentally measured parameters of aluminum to produce useful amplitude and phase shift information applicable to the concentration and direction of laser light. Amplitude and phase are plotted vs angle of incidence for several important laser wavelengths in the near UV, visible, and IR spectral regions.

Williams, M. D.

1982-01-01

20

Polytetrafluoroethylene/TiO2 Composite Pellets as Sulfur Adsorbents for Pressure Oxidation Leaching of Chalcopyrite  

Science.gov (United States)

In this study, we report the use of polytetrafluoroethylene/titanium dioxide (PTFE/TiO2) composite pellets as sulfur adsorbents in the extraction of copper from chalcopyrite by pressure oxidation leaching. PTFE/TiO2 composites of various compositions were prepared by compression molding followed by pelletization. The mass percentage of TiO2 filler in the PTFE matrix was varied from 0 to 35 wt pct. With the use of the composite pellets, significant enhancements in copper leaching were observed, indicating their role as adsorbents for the adsorption of molten elemental sulfur. In particular, the enhancement in copper extraction was increasingly pronounced (from 75 to 89 pct) with the increase of the mass percentage of TiO2 in the composite pellets from 0 to 35 wt pct. This is reasoned to result from the loss of TiO2 domains from the pellet surface, which creates additional rough hydrophobic surface to better capture elemental sulfur. The composite pellet adsorbents show excellent reusability, with the performance well maintained for 10 leaching cycles. In addition, the effectiveness of composite adsorbents at different chalcopyrite pulp densities was also investigated.

Govindaiah, Patakamuri; Grundy, Mark; Guerra, Eduard; Choi, Yeonuk; Ye, Zhibin

2015-01-01

 
 
 
 
21

Improvement of corrosion properties of microarc oxidation coating on magnesium alloy by optimizing current density parameters  

Science.gov (United States)

The microstructure, composition and corrosion performance of oxide coatings formed on AM60B alloy using microarc oxidation techniques at different waveforms of applied current densities were investigated within this study. It is found that the use of optimizing current density waveforms, i.e. decaying freely current density in the later stage and stepped decreasing current density, significantly improved the microstructure of oxide coatings compared with the constant current density mode, which are connected with changes in behaviors of spark discharges on the surface in oxidation process. The optimal waveform of current density is showed to be decaying freely current density in the later stage, which results in sealing the originally formed large micropores. The optimisation of the microstructure results in a significant improvement of the corrosion resistance of oxide coating.

Liang, Jun; Hu, Litian; Hao, Jingcheng

2007-06-01

22

The Effect of Titania Sol in Phosphate Electrolyte on Microarc Oxidation Coatings on Aluminum Alloy  

Science.gov (United States)

Black and gray microarc oxidation coatings have been obtained on 2A70 Aluminum alloy in phosphate electrolyte with and without titania sol, respectively. The growth process of the microarc oxidation coating in the electrolyte with titania sol was investigated. The coating was characterized by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray. The coating thickness was measured by eddy current thickness meter. The results show that the titania sol increase the growth rate of microarc oxidation coating. In both cases the composition of coatings contain Al and O, and are mainly composed of ?-Al2O3 and AlPO4. Compared with the gray coating, large amount of Ti is found on the surface of black coating. The titania sol added in the electrolyte results in Ti in the coating, in the form of TiO and Al2TiO5.

Tang, Ming Qi; Li, Wei Ping; Liu, Hui Cong; Zhu, Li Qun

23

Properties and uranium adsorptivity of the aluminium-activated carbon composite adsorbent and aluminium hydroxide  

International Nuclear Information System (INIS)

The effect of hydrolysis temperature of aluminium chloride on the properties of the products was studied to clear the uranium adsorptivity of the composite adsorbent (C-Al-OH). The aluminium hydroxide prepared at low temperature indicated a X-ray diffraction pattern of byerite. The X-ray diffraction intensity of byerite decreased and the intensity of pseudo-boehmite increased with increasing the hydrolysis temperature. Several adsorbents which were crystalline revealed low adsorptive capacity for uranium. The adsorptive capacity of the aluminium hydroxide for uranium was closely proportional to the surface area and the alkaline consumption, but was not related to the pore size distribution. On the other hand, the adsorptive capacity of the composite adsorbent was related to the volume of pores larger than 100 A in radius. (auth.)

24

Metal oxide coating on carbon nanotubes by a methanol-thermal method.  

Science.gov (United States)

A methanol-thermal method has been developed to fabricate one-dimensional composite nanowires by coating multiwalled carbon nanotubes with lanthanum oxide and iron oxide, respectively. The coating structure and composition have been investigated by transmission electron microscopy and the X-ray energy dispersive spectrum. Magnetic measurement for the iron oxide coatings indicated that the coercivity has been enhanced after coating. The method reported here provides a novel procedure for the fabrication of one-dimensional composite nanostructures. PMID:16060156

Lin, J; Huang, Y; Ding, X X; Cheng, C; Tang, C; Qi, S R

2005-06-01

25

ADSORPTION OF Cr(VI) FROM AQUEOUS SOLUTION USING CARBON-MICROSILICA COMPOSITE ADSORBENT  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: English Abstract in english In this work, Microsilica, one kind of industry solid waste material, was utilized firstly to prepare a carbon-Microsilica composite adsorbent from a partial carbonization, mixture and sulfoxidation process and was proposed for the removal of Cr(VI) from solutions. The surface chemistry characterist [...] ics of the prepared adsorbent were analysis by XPS and FT-IR. The characterization results indicated that an abundant of oxygen functional groups, such as hydroxyl, carboxyl and sulfonic groups, were introduced into the surface of the prepared composite adsorbent. Meanwhile, the adsorption characteristics of Cr(VI) onto the adsorbent in aqueous solutions was studied as a function of solution pH, ionic strength, contact time, and temperature. The results showed that Cr(VI) adsorption onto the adsorbent is strongly dependent on pH and, to a lesser extent, ionic strength. Kinetics data were found to follow the pseudo-second-order kinetic model while the adsorption data corresponded to L-shape adsorption isotherm which corresponds to the classification of Giles. Activation thermodynamic parameters, such as activation enthalpy (?H*), activation entropy (?S*), activation Gibbs free energy (?G*) and activation energy (E), have been evaluated and the possible adsorption mechanism also was suggested.

DEYI, ZHANG; YING, MA; HUIXIA, FENG; YUAN, HAO.

2012-03-01

26

ADSORPTION OF Cr(VI FROM AQUEOUS SOLUTION USING CARBON-MICROSILICA COMPOSITE ADSORBENT  

Directory of Open Access Journals (Sweden)

Full Text Available In this work, Microsilica, one kind of industry solid waste material, was utilized firstly to prepare a carbon-Microsilica composite adsorbent from a partial carbonization, mixture and sulfoxidation process and was proposed for the removal of Cr(VI from solutions. The surface chemistry characteristics of the prepared adsorbent were analysis by XPS and FT-IR. The characterization results indicated that an abundant of oxygen functional groups, such as hydroxyl, carboxyl and sulfonic groups, were introduced into the surface of the prepared composite adsorbent. Meanwhile, the adsorption characteristics of Cr(VI onto the adsorbent in aqueous solutions was studied as a function of solution pH, ionic strength, contact time, and temperature. The results showed that Cr(VI adsorption onto the adsorbent is strongly dependent on pH and, to a lesser extent, ionic strength. Kinetics data were found to follow the pseudo-second-order kinetic model while the adsorption data corresponded to L-shape adsorption isotherm which corresponds to the classification of Giles. Activation thermodynamic parameters, such as activation enthalpy (?H*, activation entropy (?S*, activation Gibbs free energy (?G* and activation energy (E, have been evaluated and the possible adsorption mechanism also was suggested.

DEYI ZHANG

2012-03-01

27

Adsorption properties of Cs+ for composite adsorbents and their irradiation stabilities  

International Nuclear Information System (INIS)

Novel composite adsorbents using impregnation-precipitation methods have been developed; these fine crystals are loaded in the macro-pores of porous silica gels and zeolites. The 2 following composite adsorbents: KCoFC-NM (NM: natural mordenite, 0.4-1.0 mm), KCoFC-SG (SG: porous silica gel, NH and Q-10)) were prepared by impregnation-precipitation methods. This article presents the results of tests about their characterization, their selective adsorption ability of Cs137 and their irradiation stability. It is shown that the KCoFC-SG and KCoFC-NM composites are thus efficient for the selective separation of Cs137 in low-level radioactive waste (LLW) containing highly concentrated sodium nitrate

28

Development of Composite Adsorbents for LLW Treatment and Their Adsorption Properties for Cs and Sr - 13127  

Energy Technology Data Exchange (ETDEWEB)

In this study, the composite adsorbents (KCoFC-NM (NM: natural mordenite), KCoFC-SG (SG: porous silica gel), AMP-SG and so on) were prepared by impregnation-precipitation methods. As for the distribution properties, the largest K{sub d,Cs} value of 3.8 x 10{sup 4} cm{sup 3}/g was obtained for KCoFC-SG (Davi.) composite. KCoFC-SG (NH, MB5D) and T-KCFC also had relatively large K{sub d,Cs} values above 1.0 x 10{sup 4} cm{sup 3}/g. The uptake rate of Cs{sup +} ions was examined by batch method. KCoFC-SG (NH, MB5D) and AMP-SG (Davi.) had relatively large uptake rate of Cs{sup +}, and the uptake attained equilibrium within 1 h. The maximum uptake capacity of Cs{sup +} ions was estimated to be above 0.5 mmol/g for KCoFC-NM and KCoFC-CP composites. KCoFC-X composite had a relatively large uptake capacity of Cs{sup +} ions (0.23 mmol/g > 0.17 mmol/g (T-KCFC)) and this composite also had a selectivity towards Sr{sup 2+} ions; KCoFC-X is effective adsorbent for both Cs{sup +} and Sr{sup 2+} ions. The largest value of K{sub d,Sr} was estimated to be 218 cm{sup 3}/g for titanic acid-PAN. Titanic acid-PAN had the largest uptake rate of Sr{sup 2+} ions, and the uptake attained equilibrium within 8 h. Adsorbability of other nuclides was further examined by batch method. All adsorbents had adsorbability for Rb{sup +} and RuNO{sup 3+} ions. KCoFC-SG (NH), KCoFC-CP and T-KCFC had higher selectivity towards Cs{sup +} than other adsorbents; these adsorbents had adsorbability to Cs{sup +} ions even in the presence of Ba{sup 2+}, Ca{sup 2+} and Mg{sup 2+} ions. The separation factor of K{sub d,Sr}/K{sub d,Ba} for titanic acid-PAN was about 1, indicating that the K{sub d,Sr} for titanic acid-PAN tends to decrease with Ba{sup 2+} concentration. As for the breakthrough properties, the largest 5 % breakpoint and 5 % breakthrough capacity of Cs{sup +} ions were estimated to be 47.1 cm{sup 3} and 0.07 mmol/g for the column of KCoFC-SG (NH), respectively. The order of 5 % breakthrough capacity of Cs{sup +} is as follows; KCoFC-SG (NH) > KCoFC-NM > KCoFC-SG (Q-10) > T-KCFC > KCoFC-X > KCoFC-CP. From the results of batch and column experiments, the composite adsorbent of KCoFC-SG (NH) was effective for the uptake of Cs{sup +} ions, and KCoFC-X composite was useful for the uptake of both Cs{sup +} and Sr{sup 2+} ions. The estimation of irradiation stability and the uptake properties using the actual wastes are further essential for the practical operation. (authors)

Susa, Shunsuke; Mimura, Hitoshi [Dept. of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University, Aramaki-Aza-Aoba 6-6-01-2, Sendai, 980-8579 (Japan); Ito, Yoshiyuki; Saito, Yasuo [Nuclear Science and Engineering Directorate, Japan Atomic Energy Agency, 2-4 Shirakata Shirone, Naka-gun, Ibaraki, 319-1195 (Japan)

2013-07-01

29

A method for preparing ferric activated carbon composites adsorbents to remove arsenic from drinking water  

International Nuclear Information System (INIS)

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 (Fe3O4), maghemite (?-Fe2O3), hematite (?-Fe2O3) and goethite (?-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 viacity 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 0.5 mg/L

30

Effect of potassium fluoride in electrolytic solution on the structure and properties of microarc oxidation coatings on magnesium alloy  

Science.gov (United States)

Oxide coatings were produced on AM60B magnesium alloy substrate making use of microarc oxidation (MAO) technique. The effect of KF addition in the Na 2SiO 3-KOH electrolytic solution on the microarc oxidation process and the structure, composition, and properties of the oxide coatings was investigated. It was found that the addition of KF into the Na 2SiO 3-KOH electrolytic solution caused increase in the electrolyte conductivity and decrease in the work voltage and final voltage in the MAO process. Subsequently, the pore diameter and surface roughness of the microarc oxidation coating were decreased by the addition of KF, while the coating compactness was increased. At the same time, the phase compositions of the coatings also varied after the addition of KF in the electrolytic solution, owing to the participation of KF in the reaction and its incorporation into the oxide coating. Moreover, the coating formed in the electrolytic solution with KF had a higher surface hardness and better wear-resistance than that formed in the solution without KF, which was attributed to the changes in the spark discharge characteristics and the compositions and structures of the oxide coatings after the addition of KF.

Liang, Jun; Guo, Baogang; Tian, Jun; Liu, Huiwen; Zhou, Jinfang; Xu, Tao

2005-10-01

31

Desorption of uranium from titanium-activated carbon composite adsorbent with acidic eluent, 1  

International Nuclear Information System (INIS)

An investigation was carried out on the desorption of uranium from titanium-activated carbon composite adsorbent with acidic eluent by the batch process. The rate of desorption of uranium with acidic eluent depended on temperature, showing an increase as the temperature was raised. But the rate of desorption with acidic eluent was less dependent on temperature than that obtained when mixed eluent of sodium carbonate-sodium hydrogencarbonate was used. The rate of desorption of uranium did not vary in the range of concentration from 0.3 to 0.5 N, and the rate of desorption with sulfuric acid was slightly higher than that obtained when hydrochloric acid was used. The amount of dissolved titanium decreased as the ratio of adsorbent to eluent (RAE) was increased. At RAE of 10 %, the percentage of dissolved titanium (DTI) was below 0.38 % with sulfuric acid, below 0.7 % with hydrochloric acid. These values were found to be higher than the ones with the carbonate eluent. The elements except uranium, which were adsorbed on the adsorbent, were eluted simultaneously with acidic eluent. The regeneration of the adsorbent after desorption, therefore, was found to be unnecessary. In a repeated test of adsorption-desorption treatment up to five times, the percentage of uranium adsorbed from natural sea water was approximately constant of 85 %. From these results, the application of column process to the desorption of uranium with acidic eluent at room temperature was proposed to be nt at room temperature was proposed to be feasible. (author)

32

Real time evaluation of composition and structure of concanavalin A adsorbed on a polystyrene surface.  

Science.gov (United States)

In situ qualitative and quantitative evaluations of adsorbed submonolayers and multilayers of the protein Concanavalin A (ConA) on a polystyrene surface were carried out by attenuated total reflection infrared spectroscopy. The influence of pH and adsorption time on the composition and structure of the adsorbed protein layers was investigated by comparison of the experimental spectra with simulated spectra of hypothetical multilayer systems with the assumed composition, thickness, and structure. This methodology allows the differentiation of observed spectral changes that result from pure optical effects, associated with the passing of an incident beam through the multilayer system, from the chemical and structural changes caused by physicochemical interactions of proteins with polymer surfaces. This represents significant progress since small variations in the band positions or intensities of amide I and amide II infrared absorbance bands have an important interpretation consequence. The applied methodology significantly reduces the misinterpretation of recorded spectra of protein layers and is rewarded by a deep insight of the structure and composition of the samples. The composition, structure, and kinetics of the adsorption of ConA and hydration level of the adsorbed layers were evaluated in detail. Competitive adsorption of bovine serum albumin on pre-adsorbed ConA layers also was investigated to characterize the ConA surface distribution. Parallel studies using X-ray photoelectron spectroscopy support the conclusions drawn from infrared spectroscopic investigations on ConA molecular distributions at the polymer surface. Two-step models that describe ConA submonolayer formation at pH 4.8 and multilayer formation at pH 7.8 are proposed. PMID:18376883

Mielczarski, Jerzy A; Dong, Jie; Mielczarski, Ela

2008-04-24

33

Synthesis and properties of a magnetic core-shell composite nano-adsorbent for fluoride removal from drinking water  

Science.gov (United States)

An adsorbent for fluoride removal from drinking water was prepared by coating Fe-Ti bimetallic oxide on magnetic Fe3O4 particles by co-precipitation. The adsorbent was a nanosized composite with a core-shell structure comprising a magnetic Fe3O4 core of 10-20 nm in diameter and an amorphous adsorbent shell of several nanometer thickness. The synthesis parameters were optimized to give high adsorption capacity and high magnetization. The optimized mass ratio of the Fe-Ti bimetallic oxide shell to Fe3O4 core was 2.72. The adsorption isotherm was well fitted with the Langmuir isotherm and the saturation adsorption capacity 57.22 mg/g adsorbent. Adsorption was fast and reached equilibrium within 2 min. The nano-adsorbent was superparamagnetic with a saturation magnetization of 18.4 emu/g, which allowed rapid separation of the adsorbent from the water solution by an external magnet.

Zhang, Chang; Chen, Lin; Wang, Ting-Jie; Su, Chao-Li; Jin, Yong

2014-10-01

34

Bio sorption process for uranium (VI) by using algae-yeast-silica gel composite adsorbent  

International Nuclear Information System (INIS)

Many yeast, algae, bacteria and various aquatic flora are known to be capable of concentrating metal species from dilute aqueous solution. Many researcher have found that non-living biomaterials can be used to accumulate metal ions from environment. In recent studies, mainly two process are used in biosorption experiments. These are the use of free cells and the use of immobilized cells on a solid support. A variety of inert supports have been used to immobilize biomaterials either by adsorption or physical entrapment. This uptake is often considerable and frequently selective, and occurs via a variety of mechanisms including active transport, ion exchange or complexation, and adsorption or inorganic precipitation. Biosorbent may be used as an ion exchange material. Adsorption occurs through interaction of the metal ions with functional groups that are found in the cell wall biopolymers of either living or dead organisms. In this study, the algae-yeast-silica gel composite adsorbent was tested for its ability to recover U(VI) from diluted aqueous solutions. Macro marine algae (Jania rubens.), yeast (Saccharomyces cerevisiae) and silica gel were used to prepare composite adsorbent. The ability of the composite biosorbent to adsorb uranium (VI) from aqueous solution has been studied at different optimized conditions of pH, concentration of U(VI), temperature, contact time and matrix ion effect was also investigated. The adsorption patterns of uranium on the composite biosorbent were investigated by the Langmuir, Freundlich and Dubinin-Radushkhevic isotherms. The thermodynamic parameters such as variation of enthalpy ?H, variation of entropy ?S and variation of Gibbs free energy ?G were calculated. The results suggested that the macro algae-yeast-silica gel composite sorbent is suitable as a new biosorbent material for removal of uranium ions from aqueous solutions

35

Testing and evaluation of oxide-coated iridium/rhenium chambers  

Science.gov (United States)

Iridium-coated rhenium provides long life operation of radiation-cooled rockets at temperatures up to 2200 C. Ceramic oxide coatings could be used to increase iridium/rhenium rocket lifetimes and allow operation in highly oxidizing environments. Ceramic oxide coatings promise to serve as both thermal and diffusion barriers for the iridium layer. Seven ceramic oxide-coated iridium/rhenium, 22 N rocket chambers were tested on gaseous hydrogen/gaseous oxygen propellants. Five chambers had thick (over 10 mils), monolithic coatings of either hafnia or zirconia. Two chambers had coatings with thicknesses less than 5 mils. One of these chambers had a thin-walled coating of zirconia infiltrated with sol gel hafnia. The other chamber had a coating composed of an iridium/oxide composite. The purpose of this test program was to assess the ability of the oxide coatings to withstand the thermal shock of combustion initiation, adhere under repeated thermal cycling, and operate in aggressively oxidizing environments. All of the coatings survived the thermal shock of combustion and demonstrated operation at mixture ratios up to 11. The iridium/oxide composite coated chamber included testing for over 29 minutes at mixture ratio 16. The thicker-walled coatings provided the larger temperature drops across the oxide layer (up to 570 C), but were susceptible to macrocracking and eventual chipping at a stress concentrator. The cracks apparently resealed during firing, under compression of the oxide layer. The thinner-walled coatings did not experience the macrocracking and chipping of the chambers seen with the thick, monolithic coatings. However, burnthroughs in the throat region did occur in both of the thin-walled chambers at mixture ratios well above stochiometric. The burn-throughs were probably the result of oxygen-diffusion through the oxide coating that allowed the underlying iridium and rhenium layers to be oxidized. The results of this test program indicated that the thin-walled oxide coatings are better suited for repeated thermal cycling than the thick-walled coating, while thicker coatings may be required for operation in aggressively oxidizing environments.

Reed, Brian D.

1993-01-01

36

Extraction of uranium from sea water with the granular composite adsorbent by using the fixed bed  

International Nuclear Information System (INIS)

To clarify the technical problems existing in the extraction process of uranium from sea water, uranium was extracted from natural sea water, with the granulated C-Ti-OH composite adsorbent. The adsorption of uranium from sea water was carried out by using the fixed bed that had been designed in our laboratory. The uranium recovery from the sea water was 13.9 % in the adsorption process of 56sub(d). The adsorbed uranium was eluted from the adsorbent with 0.5 sub(N) NaHCO3-0.5 sub(N) Na2CO3 soln. at 700C. The elution recovery was 97.4 % after 35 h. The uranium contained in the eluate was concentrated in the anion exchange process to 20 times as much as in the eluate, and then 100 times in the solvent extraction process with oxine-chloroform and TOA- kerosene. About 0.7 g of yellow cake was prepared from natural sea water, and it was identified to be 2UO2.NH3.3H2O by X-ray diffraction method and X-ray fluorometry. (author)

37

Infrared analysis of electrochromic nickel oxide coatings  

Science.gov (United States)

Electrochromic nickel oxide based thin film coatings have been prepared on transparent conducting electrodes using anodic electrodeposition and colloidal precipitation techniques. Coatings were deposited from solutions containing nickel sulphate, ammonium hydroxide, and a solution stabilizer, polyoxyethylene sorbitan monolaurate (a nonionic surfactant). The films were cycled between their colored and bleached states using a 3-electrode cell containing 1 M KOH electrolyte. The dependence of the optical and electrochromic properties of the coatings on bath concentration and deposition time was investigated. Films were analyzed using Fourier transform spectrophotometry, UV/VIS/NIR spectrophotometry and cyclic voltammetry. The best films produced by anodic electrodeposition on indium tin oxide coated glass substrates have solar transmittance of 0.82 and 0.22 in the bleached and colored state, respectively. Corresponding optimum values for films produced by colloidal precipitation are 0.82 and 0.47. An O-H stretch at 3647 cm-1 corresponding to Ni(OH)2 was found for both anodic and colloidal deposited films in the reduced state. In the oxidized state a stretch was identified at 564 cm-1 characteristic of NiOOH.

Hutchins, Michael G.; McMeeking, Graham; Crnjak Orel, Zorica

1992-11-01

38

Long Life Testing of Oxide-Coated Iridium/Rhenium Rockets  

Science.gov (United States)

22-N class rockets, composed of a rhenium (Re) substrate, an iridium (Ir) coating, and an additional composite coating consisting of Ir and a ceramic oxide, were tested on gaseous oxygen/gaseous hydrogen (GO2/GH2) propellants. Two rockets were tested, one for nearly 39 hours at a nominal mixture ratio (MR) of 4.6 and chamber pressure (Pc) of 469 kPa, and the other for over 13 hours at a nominal MR of 5.8 and 621 kPa Pc. Four additional Ir/Re rockets, with a composite Ir-oxide coating fabricated using a modified process, were also tested, including one for 1.3 hours at a nominal MR of 16.7 and Pc of 503 kPa. The long lifetimes demonstrated on low MR GO2/GH2 suggest greatly extended chamber lifetimes (tens of hours) in the relatively low oxidizing combustion environments of Earth storable propellants. The oxide coatings could also serve as a protective coating in the near injector region, where a still-mixing flowfield may cause degradation of the Ir layer. Operation at MR close to 17 suggests that oxide-coated Ir/Re rockets could be used in severely oxidizing combustion environments, such as high MR GO2/GH2, oxygen/hydrocarbon, and liquid gun propellants.

Reed, Brian D.

1995-01-01

39

Removal of phosphorus by a composite metal oxide adsorbent derived from manganese ore tailings.  

Science.gov (United States)

The selective adsorption of phosphate (P) from wastewater is a promising method for controlling eutrophication in water bodies. In this study, an adsorbent of composite metal oxides (CMOMO) was synthesized from manganese ore tailings by the process of digestion-oxidation-coprecipitation. CMOMO was characterized using several methods, and its adsorption behaviors for phosphate were investigated. Based on the results from SEM and BET analysis, CMOMO exhibited a rough surface and a large surface area (307.21 m(2)/g). According to the results of EDAX, XRD and XPS, its main constituents were determined to be amorphous FeOOH, MnO(2) and AlOOH. The kinetic data were best fit using the Elovich model due to its complicate composites. The maximal adsorption capacity of P would increase with elevated temperatures. Additionally, it was found that the P removal efficiency decreased with an increase of pH (4-10) or a decrease of ion strength (1-0.01 M). The coexisting anions had little effects on phosphate removal, implying the specific adsorption of P by CMOMO. Furthermore, the desorption and reuse results indicated that this adsorbent could be regenerated using alkali solutions. PMID:22464586

Liu, Ting; Wu, Kun; Zeng, Lihua

2012-05-30

40

Characteristics of cobalt adsorption on titanium(IV) oxide-alumina composite adsorbents in high temperature water  

International Nuclear Information System (INIS)

Titanium(IV) oxide-alumina composite adsorbents were prepared by hydrolysis of titanium (IV) and aluminum isopropoxide followed by drying and calcining their hydroxides, and their cobalt adsorption in high-temperature water was investigated. The adsorbent composed of titanium(IV) oxide and alumina, being 0.55 in mole fraction of titanium(IV) oxide and calcined at 500 0C for 5 h showed a surface area of 124 m2.g-1 and an equilibrium adsorption capacity of 110 ?eq.g-1 at 280 0C in a pH 4.45 solution containing cobalt ion at 3 ppm. The specific surface area of the composite adsorbent decreasea with increasing mole fraction of titanium(IV) oxide. However, the cobalt adsorption capacity at 280 0C increased with the titanium(IV) oxide mole fraction. Therefore, the cobalt adsorption in high temperature water seems to be controlled by titanium(IV) oxide in the composite adsorbent. From the measured adsorption capacity, it appears that a high specific surface area of titanium(IV) oxide in the adsorbent is maintained even when the adsorbent is calcined at the sintering temperature of titanium(IV) oxide. (author)

 
 
 
 
41

Synthesis, structural and mechanical characterization of sputtered tungsten oxide coatings  

International Nuclear Information System (INIS)

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 O2/p 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 ?-W and ?-W3O phases were observed ( 75 at.%, a nanocrystalline (WO3) 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 ? 23 GPa for pure W down to ? 7 GPa for WO3 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 c < 15 N) to the steel substrate because the depositions were carried out intentionally without an adhesion interfacial layer

42

Antifriction Property of Microarc Oxidation Coating on Titanium Alloy Under Solid Lubricating Sliding Condition  

Science.gov (United States)

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.

Wang, Y. M.; Jiang, B. L.; Guo, L. X.; Lei, T. Q.

43

A Comparative Study of Agarose-Nickel prototype Composite Adsorbent and Commercial Streamline DEAE Adsorbent: Physical and Hydrodynamical Assessments  

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Full Text Available Expanded bed adsorption (EBA is an integration technology for capturing target bioproducts directly from unclarified feedstock, designing and applying a good adsorbent affects its performance. In present work, a novel matrix has been developed for expanded bed adsorption process. The prepared matrix was manufactured using water-in-oil emulsification method. Desirable adsorbents tend to be of small size, high density as well as high porosity. Here, the prepared matrices had regular spherical shape, wet density of 1.95, followed logarithmic normal size distribution within the range of 50-200 µm, mean diameter of 126.4 µm, and 91.93% prosily. The Richardson-Zaki equation expressed the bed expansion and operation flow rate for the prepared matrix and Streamline DEAE. In addition, the theoretical prediction of correlation parameters (Ut and n was also measured. To characterize the hydrodynamic properties in the expanded bed, the residence time distribution method was used. The physical and hydrodynamic properties of the fabricated matrix were studied and compared with those of the commercial Streamline DEAE matrix. The results indicated that the prepared matrices showed good expansion and stability in the bed, and are thus suitable for expanded bed applications.

F. Asghari

2012-01-01

44

Removal of dieldrin from aqueous solution by a novel triolein-embedded composite adsorbent  

Energy Technology Data Exchange (ETDEWEB)

In this study, a novel triolein-embedded activated carbon composite adsorbent (CA-T) was prepared and applied for the adsorption and removal of dieldrin from aqueous systems. Experiments were carried out to investigate the adsorption behavior of dieldrin on CA-T, including adsorption isotherms, adsorption kinetics, the influence of initial concentration, temperature, shaking speed, pH and the addition of humic acid (HA) on adsorption. The adsorption isotherms accorded with Freundlich equation. Three kinetics models, including pseudo-first-order, pseudo-second-order and intraparticle diffusion models, were used to fit the experimental data. By comparing the correlation coefficients, it was found that both pseudo-second-order and intraparticle diffusion models were used to well describe the adsorption of dieldrin on CA-T. The addition of HA had little effect on dieldrin adsorption by CA-T. Results indicated that CA-T appeared to be a promising adsorbent for removing lipophilic dieldrin in trace amount, which was advantageous over pure granular activated carbon (GAC). The adsorption rate increased with increasing shaking speed, initial concentration and temperature, and remained almost unchanged in the pH range of 4-8. Thermodynamic calculations indicated that the adsorption reaction was spontaneous with a high affinity and the adsorption was an endothermic reaction.

Ru Jia [State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China) and Graduate School of Chinese Academy of Sciences, Beijing 100039 (China)]. E-mail: rujia_china@hotmail.com; Liu Huijuan [State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China)]. E-mail: hjliu@rcees.ac.cn; Qu Jiuhui [State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China)]. E-mail: jhqu@rcees.ac.cn; Wang Aimin [State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China)]. E-mail: wangaimin199771@sina.com.cn; Dai Ruihua [State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China) and Graduate School of Chinese Academy of Sciences, Beijing 100039 (China)]. E-mail: dairuihualg@sohu.com

2007-03-06

45

Removal of dieldrin from aqueous solution by a novel triolein-embedded composite adsorbent  

International Nuclear Information System (INIS)

In this study, a novel triolein-embedded activated carbon composite adsorbent (CA-T) was prepared and applied for the adsorption and removal of dieldrin from aqueous systems. Experiments were carried out to investigate the adsorption behavior of dieldrin on CA-T, including adsorption isotherms, adsorption kinetics, the influence of initial concentration, temperature, shaking speed, pH and the addition of humic acid (HA) on adsorption. The adsorption isotherms accorded with Freundlich equation. Three kinetics models, including pseudo-first-order, pseudo-second-order and intraparticle diffusion models, were used to fit the experimental data. By comparing the correlation coefficients, it was found that both pseudo-second-order and intraparticle diffusion models were used to well describe the adsorption of dieldrin on CA-T. The addition of HA had little effect on dieldrin adsorption by CA-T. Results indicated that CA-T appeared to be a promising adsorbent for removing lipophilic dieldrin in trace amount, which was advantageous over pure granular activated carbon (GAC). The adsorption rate increased with increasing shaking speed, initial concentration and temperature, and remained almost unchanged in the pH range of 4-8. Thermodynamic calculations indicated that the adsorption reaction was spontaneous with a high affinity and the adsorption was an endothermic reaction

46

Kinetics and mechanism of arsenate removal by nanosized iron oxide-coated perlite.  

Science.gov (United States)

This study discussed the adsorption kinetics of As(V) onto nanosized iron oxide-coated perlite. The effects of pH, initial concentration of As(V) and common anions on the adsorption efficiency were also investigated. It was observed that a 100% As(V) adsorption was achieved at pH value of 4-8 from the initial concentration containing 1.0 mg-As(V)L(-1) and the adsorption percentage depended on the initial concentration; the phosphate and silicate ions would not interfere with the adsorption efficiency. Furthermore, nanosized iron oxide-coated perlite (IOCP) has been shown to be an effective adsorbent for the removal of arsenate from water. The adsorption kinetics were studied using pseudo-first- and pseudo-second-order models, and the experimental data fitted well with the pseudo-second-order model. Moreover, it suggests that the Langmuir isotherm is more adequate than the Freundlich isotherm in simulating the adsorption isotherm of As(V). The adsorption rate constant is 44.84 L mg(-1) and the maximum adsorption capacity is 0.39 mg g(-1). These findings indicate that the adsorption property of IOCP gives the compound a great potential for applications in environmental remediation. PMID:21282000

Mostafa, M G; Chen, Yen-Hua; Jean, Jiin-Shuh; Liu, Chia-Chuan; Lee, Yao-Chang

2011-03-15

47

Co-precipitation synthesis of nano-composites consists of zinc and tin oxides coatings on glass with enhanced photocatalytic activity on degradation of Reactive Blue 160 KE2B.  

Science.gov (United States)

Nano-composite containing zinc oxide-tin oxide was obtained by a facile co-precipitation route using tin chloride tetrahydrate and zinc chloride as precursors and coated on glass by Doctor Blade deposition. The crystalline structure and morphology of composites were evaluated by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The XRD results showed peaks relative to zinc oxide with hexagonal wurtzite structure and tin oxide with tetragonal structure. FESEM observations showed that the nano-composite consisted of aggregates of particles with an average particle size of 18nm. The photocatalytic activity of the pure SnO2, pure ZnO, ZnSnO3-Zn2SnO4 and ZnO-SnO2 nano-structure thin films was examined using the degradation of a textile dye Reactive Blue 160 (KE2B). ZnO-SnO2 nano-composite showed enhanced photo-catalytic activity than the pure zinc oxide and tin oxide. The enhanced photo-catalytic activity of the nano-composite was ascribed to an improved charge separation of the photo-generated electron-hole pairs. PMID:25265524

Habibi, Mohammad Hossein; Mardani, Maryam

2015-02-25

48

Co-precipitation synthesis of nano-composites consists of zinc and tin oxides coatings on glass with enhanced photocatalytic activity on degradation of Reactive Blue 160 KE2B  

Science.gov (United States)

Nano-composite containing zinc oxide-tin oxide was obtained by a facile co-precipitation route using tin chloride tetrahydrate and zinc chloride as precursors and coated on glass by Doctor Blade deposition. The crystalline structure and morphology of composites were evaluated by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The XRD results showed peaks relative to zinc oxide with hexagonal wurtzite structure and tin oxide with tetragonal structure. FESEM observations showed that the nano-composite consisted of aggregates of particles with an average particle size of 18 nm. The photocatalytic activity of the pure SnO2, pure ZnO, ZnSnO3-Zn2SnO4 and ZnO-SnO2 nano-structure thin films was examined using the degradation of a textile dye Reactive Blue 160 (KE2B). ZnO-SnO2 nano-composite showed enhanced photo-catalytic activity than the pure zinc oxide and tin oxide. The enhanced photo-catalytic activity of the nano-composite was ascribed to an improved charge separation of the photo-generated electron-hole pairs.

Habibi, Mohammad Hossein; Mardani, Maryam

2015-02-01

49

Chromium oxide coatings improve thermal emissivity of alumina  

Science.gov (United States)

Chromium oxide coatings improve thermal radiation characteristics of alumina-coated heater-cathode systems in vacuum tubes. Chromium oxide is applied either as a surface layer or as a doping material. The new coatings eliminate the high temperature migration problems of carbon surface treatments.

Upshaw, V.

1966-01-01

50

Improved transmittance measurement with a magnesium oxide coated integrating sphere  

Science.gov (United States)

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.

Bowman, R. L.; Spisz, E. W.

1972-01-01

51

Study on the adsorption isosteres of the composite adsorbent CaCl{sub 2} and expanded graphite  

Energy Technology Data Exchange (ETDEWEB)

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.

Li, S.L. [Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai 200240 (China); Wu, J.Y., E-mail: jywu@sjtu.edu.c [Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai 200240 (China); Xia, Z.Z.; Wang, R.Z. [Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai 200240 (China)

2011-02-15

52

An efficient removal of methyl orange dye from aqueous solution by adsorption onto chitosan/MgO composite: A novel reusable adsorbent  

Science.gov (United States)

We report a novel multi-functional magnesium oxide (MgO) immobilized chitosan (CS) composite was prepared by chemical precipitation method. The CS-MgO composite was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy and zeta potential. The composite was applied as a novel adsorbent for removal of methyl orange model dye and the effect of adsorbent dosage, pH and contact time were studied. The adsorption kinetics followed a pseudo second order reaction. The adsorbent efficiency was unaltered even after five cycles of reuse. In addition, the composite exhibited a superior antibacterial efficacy of 93% within 24 h against Escherichia coli as measured by colony forming units. Based on the data of present investigation the composite being a biocompatible, eco-friendly and low-cost adsorbent with antibacterial activity could find potential applications in variety of fields and in particular environmental applications.

Haldorai, Yuvaraj; Shim, Jae-Jin

2014-02-01

53

An efficient removal of methyl orange dye from aqueous solution by adsorption onto chitosan/MgO composite: A novel reusable adsorbent  

Energy Technology Data Exchange (ETDEWEB)

We report a novel multi-functional magnesium oxide (MgO) immobilized chitosan (CS) composite was prepared by chemical precipitation method. The CS–MgO composite was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy and zeta potential. The composite was applied as a novel adsorbent for removal of methyl orange model dye and the effect of adsorbent dosage, pH and contact time were studied. The adsorption kinetics followed a pseudo second order reaction. The adsorbent efficiency was unaltered even after five cycles of reuse. In addition, the composite exhibited a superior antibacterial efficacy of 93% within 24 h against Escherichia coli as measured by colony forming units. Based on the data of present investigation the composite being a biocompatible, eco-friendly and low-cost adsorbent with antibacterial activity could find potential applications in variety of fields and in particular environmental applications.

Haldorai, Yuvaraj; Shim, Jae-Jin, E-mail: jjshim@yu.ac.kr

2014-02-15

54

An efficient removal of methyl orange dye from aqueous solution by adsorption onto chitosan/MgO composite: A novel reusable adsorbent  

International Nuclear Information System (INIS)

We report a novel multi-functional magnesium oxide (MgO) immobilized chitosan (CS) composite was prepared by chemical precipitation method. The CS–MgO composite was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy and zeta potential. The composite was applied as a novel adsorbent for removal of methyl orange model dye and the effect of adsorbent dosage, pH and contact time were studied. The adsorption kinetics followed a pseudo second order reaction. The adsorbent efficiency was unaltered even after five cycles of reuse. In addition, the composite exhibited a superior antibacterial efficacy of 93% within 24 h against Escherichia coli as measured by colony forming units. Based on the data of present investigation the composite being a biocompatible, eco-friendly and low-cost adsorbent with antibacterial activity could find potential applications in variety of fields and in particular environmental applications.

55

Thermodynamic and kinetic studies of As(V) removal from water by zirconium oxide-coated marine sand.  

Science.gov (United States)

Arsenic contamination of groundwater is a major threat to human beings globally. Among various methods available for arsenic removal, adsorption is fast, inexpensive, selective, accurate, reproducible and eco-friendly in nature. The present paper describes removal of arsenate from water on zirconium oxide-coated sand (novel adsorbent). In the present work, zirconium oxide-coated sand was prepared and characterised by infrared and X-ray diffraction techniques. Batch experiments were performed to optimise different adsorption parameters such as initial arsenate concentration (100-1,000 ?g/L), dose (1-8 g/L), pH of the solution (2-14), contact time (15-150 min.), and temperature (20, 30, 35 and 40 °C). The experimental data were analysed by Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models. Furthermore, thermodynamic and kinetic parameters were evaluated to know the mode of adsorption between ZrOCMS and As(V). The maximum removal of arsenic, 97 %, was achieved at initial arsenic concentration of 200 ?g/L, after 75 min at dosage of 5.0 g/L, pH 7.0 and 27 ± 2 °C. For 600 ?g/L concentration, the maximum Langmuir monolayer adsorption capacity was found to be 270 ?g/g at 35 °C. Kinetic modelling data indicated that adsorption process followed pseudo-second-order kinetics. The mechanism is controlled by liquid film diffusion model. Thermodynamic parameter, ?H°, was -57.782, while the values of ?G° were -9.460, -12.183, -13.343 and -13.905 kJ/mol at 20, 30, 35 and 40 °C, respectively, suggesting exothermic and spontaneous nature of the process. The change in entropy, ?S°=?-0.23 kJ/mol indicated that the entropy decreased due to adsorption of arsenate ion onto the solid adsorbent. The results indicated that the reported zirconium oxide-coated marine sand (ZrOCMS) was good adsorbent with 97 % removal capacity at 200 ?g/L concentration. It is interesting to note that the permissible limit of arsenic as per World Health Organization is 10 ?g/L, and in real situation, this low concentration can be achieved through this adsorbent. Besides, the adsorption capacity showed that this adsorbent may be used for the removal of arsenic from any natural water resource. PMID:23423866

Khan, Tabrez Alam; Chaudhry, Saif Ali; Ali, Imran

2013-08-01

56

The mechanical properties of metal oxide coated polyester films  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This communication reports on a study of the microstructure, mechanical and gas barrier properties of PECVD metal oxide coatings on heat stabilised (HS) PET [poly(ethylene terephthalate)], primer-coated HS PET, filled PET and PEN [poly(ethylene naphthalate)] substrates. The coatings are highly conformal and exhibit very few large scale defects. Internal stresses in the coatings are found to be compressive for all substrates. The substrate is found to influence some of the mechanical propertie...

Henry, Bm; Howells, D.; Assender, He; Grovenor, Crm

2006-01-01

57

Antibacterial activity of zinc oxide-coated nanoporous alumina  

Energy Technology Data Exchange (ETDEWEB)

Highlights: Black-Right-Pointing-Pointer Atomic layer deposition was used to deposit ZnO on nanoporous alumina membranes. Black-Right-Pointing-Pointer Scanning electron microscopy showed continuous coatings of zinc oxide nanocrystals. Black-Right-Pointing-Pointer Activity against B. subtilis, E. coli, S. aureus, and S. epidermidis was shown. - Abstract: Nanoporous alumina membranes, also known as anodized aluminum oxide membranes, are being investigated for use in treatment of burn injuries and other skin wounds. In this study, atomic layer deposition was used for coating the surfaces of nanoporous alumina membranes with zinc oxide. Agar diffusion assays were used to show activity of zinc oxide-coated nanoporous alumina membranes against several bacteria found on the skin surface, including Bacillus subtilis, Escherichia coli, Staphylococcus aureus, and Staphylococcus epidermidis. On the other hand, zinc oxide-coated nanoporous alumina membranes did not show activity against Pseudomonas aeruginosa, Enterococcus faecalis, and Candida albicans. These results suggest that zinc oxide-coated nanoporous alumina membranes have activity against some Gram-positive and Gram-negative bacteria that are associated with skin colonization and skin infection.

Skoog, S.A. [Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Box 7115, Raleigh, NC 27695-7115 (United States); Bayati, M.R. [Department of Materials Science and Engineering, North Carolina State University, Box 7907, Raleigh, NC 27695-7907 (United States); Petrochenko, P.E. [Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Box 7115, Raleigh, NC 27695-7115 (United States); Division of Biology, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD 20993 (United States); Stafslien, S.; Daniels, J.; Cilz, N. [Center for Nanoscale Science and Engineering, North Dakota State University, 1805 Research Park Drive, Fargo, ND 58102 (United States); Comstock, D.J.; Elam, J.W. [Energy Systems Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Narayan, R.J., E-mail: roger_narayan@msn.com [Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Box 7115, Raleigh, NC 27695-7115 (United States); Department of Materials Science and Engineering, North Carolina State University, Box 7907, Raleigh, NC 27695-7907 (United States)

2012-07-25

58

Antibacterial activity of zinc oxide-coated nanoporous alumina  

International Nuclear Information System (INIS)

Highlights: ? Atomic layer deposition was used to deposit ZnO on nanoporous alumina membranes. ? Scanning electron microscopy showed continuous coatings of zinc oxide nanocrystals. ? Activity against B. subtilis, E. coli, S. aureus, and S. epidermidis was shown. - Abstract: Nanoporous alumina membranes, also known as anodized aluminum oxide membranes, are being investigated for use in treatment of burn injuries and other skin wounds. In this study, atomic layer deposition was used for coating the surfaces of nanoporous alumina membranes with zinc oxide. Agar diffusion assays were used to show activity of zinc oxide-coated nanoporous alumina membranes against several bacteria found on the skin surface, including Bacillus subtilis, Escherichia coli, Staphylococcus aureus, and Staphylococcus epidermidis. On the other hand, zinc oxide-coated nanoporous alumina membranes did not show activity against Pseudomonas aeruginosa, Enterococcus faecalis, and Candida albicans. These results suggest that zinc oxide-coated nanoporous alumina membranes have activity against some Gram-positive and Gram-negative bacteria that are associated with skin colonization and skin infection.

59

Adsorption characteristics of As(III) from aqueous solution on iron oxide coated cement (IOCC)  

International Nuclear Information System (INIS)

Contamination of potable groundwater with arsenic is a serious health hazard, which calls for proper treatment before its use as drinking water. The objective of the present study is to assess the effectiveness of iron oxide coated cement (IOCC) for As(III) adsorption from aqueous solution. Batch studies were conducted to study As(III) adsorption onto IOCC at ambient temperature as a function of adsorbent dose, pH, contact time, initial arsenic concentration and temperature. Kinetics reveal that the uptake of As(III) ion is very rapid and most of fixation occurs within the first 20 min of contact. The pseudo-second order rate equation successfully described the adsorption kinetics. Langmuir, Freundlich, Redlich-Peterson (R-P), and Dubinin-Radushkevich (D-R) models were used to describe the adsorption isotherms at different initial As(III) concentrations and at 30 g l-1 fixed adsorbent dose. The maximum adsorption capacity of IOCC for As(III) determined from the Langmuir isotherm was 0.69 mg g-1. The mean free energy of adsorption (E) calculated from the D-R isotherm was found to be 2.86 kJ mol-1 which suggests physisorption. Thermodynamic parameters indicate an exothermic nature of adsorption and a spontaneous and favourable process. The results suggest that IOCC can be suitably used for As(III) removal from aqueous solutions

60

Adsorption characteristics of uranyl ions by manganese oxide coated sand in batch mode  

International Nuclear Information System (INIS)

In this paper, the sorption properties of manganese oxide coated sand (MOCS) towards uranium(VI) from aqueous solutions were studied in a batch adsorption system. Scanning electron microscope (SEM) and infrared (IR) analyses were used to characterize MOCS. Parameters affecting the adsorption of uranium(VI), such as the contact time, salt concentration, competitive ions, temperature and initial uranium(VI) concentration, were investigated. The equilibrium adsorption data were analyzed by Langmuir, Freundlich and Redlich-Peterson models using nonlinear regressive analysis. The results indicated that the Langmuir and Redlich-Peterson models provided the best correlation of experimental data. The kinetic experimental data were analyzed using three kinetic equations including pseudo-first order equation, pseudo-second order equation and intraparticle diffusion model to examine the mechanism of adsorption and potential rate-controlling step. The process mechanism was found to be complex, consisting of both surface adsorption and pore diffusion. The effective diffusion parameter D i values estimated in the order of 10-7 cm2 s-1 indicated that the intraparticle diffusion was not the rate-controlling step. Thermodynamic study showed that the adsorption was a spontaneous, endothermic process. Adsorbed U(VI) ions were desorbed effectively (about 94.7%) by 0.1 mol L-1 HNO3. The results indicated that MOCS can be used as an efs indicated that MOCS can be used as an effective adsorbent for the treatment of industrial wastewaters contaminated with U(VI) ions. (author)

 
 
 
 
61

Microstructural study of aluminum phosphate-sealed, plasma-sprayed chromium oxide coating  

Science.gov (United States)

Microstructural characterization of aluminum phosphate-sealed, plasma-sprayed chromium oxide coating was carried out in order to study the strengthening mechanisms of the aluminum phosphate sealant in the coating. Characterization was performed using x-ray diffractometry, scanning electron microscopy, and analytical transmission electron microscopy. The structure of the sealed coating was lamellar with columnar ?-Cr2O3 grains extending through the lamella thickness. Amorphous aluminum phosphate sealant had penetrated into the structural defects of the coating such as cracks, gaps, and pores between the lamellae. The relative composition was 25 at.% aluminum and 75 at.% phosphorus for the sealant in the coating, giving the molar ratio P/Al of 3, which corresponds to that of metaphosphates Al(PO3)3. There is no indication of reaction products from the chemical reactions between the sealant and the coating. Thus, the aluminum phosphate sealing in the chromium oxide coatings can be explained mainly by adhesive binding resulting from the formation of the condensed phosphates with the appropriate adhesive properties to the coating, and not by chemical bonding resulting from the chemical reactions between the sealant and the coating.

Vippola, Minnamari; Ahmaniemi, Samppa; Vuoristo, Petri; Lepistö, Toivo; Mäntylä, Tapio; Olsson, Eva

2002-06-01

62

Fabrication of yttrium oxide and erbium oxide coatings by PVD methods  

International Nuclear Information System (INIS)

The development of insulating coatings is one of the most important subjects in fusion reactor liquid lithium blanket research and development. The compounds aluminum nitride, yttrium oxide and erbium oxide are considered to be candidate materials for ceramic coatings because of their high electrical resistance and their high compatibility with liquid lithium. In the present study, two types of PVD methods were employed for fabrication of coatings, and their properties were examined. Yttrium oxide and erbium oxide coatings were fabricated by means of radio frequency (RF) sputtering, and erbium oxide coatings were fabricated by arc source plasma assisted deposition. The coatings were all close to their stoichimetric composition, and had higher resistances than that required in the fusion reactor (102-104 ?m). The coatings had the crystallinity observed by X-ray diffraction (XRD), which were influenced by fabrication parameters as high frequency electric power or substrate temperature. Annealing after fabrication makes coatings crystallized more while the crystallinity of the coatings fabricated at low temperature were inferior to that of the coatings fabricated at higher temperature

63

Plasma deposition of oxide-coated cathodes  

Science.gov (United States)

Vacuum arc deposition is employed to create a barium and/or strontium plasma which is subsequently deposited/implanted onto a nickel cathode substrate. The primary motivation for this work is the critical need for a reliable, repeatable, long-lived thermionic cathode for the production of high power, microsecond duration microwave pulses; such cathodes may also have applicability for lower current density continuous wave devices. This novel approach to manufacturing an oxide cathode eliminates the binders that may subsequently (and unpredictably) poison cathode emission. Removal of the poisoning mechanisms has yielded oxide cathodes capable of emission densities in the 20 A/cm 2 regime. Cathode lifetime and emission may be varied via the control over the deposition parameters such as coating thickness, implantation energy, and plasma stoichiometry. The deposition is performed by generating a cathodic arc discharge at the surface of a barium or barium- strontium alloy rod. The metal plasma thus created is then deposited on the substrate which can be negatively biased to encourage implantation during the deposition process. The deposition is performed with sufficient background oxygen present to oxidize the highly reactive metal coating. The plasma deposition is monitored via a rate thickness monitor, an optical emission spectrometer for plasma composition information, and an electrostatic Langmuir probe for the determination of the plasma density and temperature profile. Cathodes thus produced are analyzed by drawing pulsed current at a constant voltage for various values of decreasing cathode temperature in order to generate practical work function distributions which provide an indication of the quality and expected life time of the cathode.

Umstattd, Ryan Jonathan

64

The effects of chemical composition of adsorbed molecular layers on lithium electrode/polymer electrolyte interface stabilization  

Science.gov (United States)

Previous work in our laboratory has shown that the adsorption of self-assembled molecular layers on a polymer electrolyte surface can make the interface between the electrolyte and a lithium metal electrode more stable and can hinder the growth of the type of passivation layer that inhibits ion movement between the electrode and electrolyte. This work is concerned with the effect that the molecular composition of the adsorbed layer has on interface stability. Several compounds of the form R?(CH 2CH 2O)?H have been found to adsorb on the surface of the polymer electrolyte and stabilize the interface. It was found that the R group could be a long, straight hydrocarbon tail capable of forming an ordered self-assembled structure or a branched hydrocarbon or a siloxane with bulky hydrocarbon groups that form a brush-type structure. Molecules of the form R?OH and R?COOH, where R was a long, straight-chain hydrocarbon, would adsorb but appeared to have much disorder in their hydrocarbon chains. It is proposed that this disorder results from a low adsorption density that results in regions where the lithium metal can come in direct contact with the polymer electrolyte causing reactions that promote interface destabilization.

Le Granvalet-Mancini, Maryline; Teeters, Dale

65

Performance of magnetic activated carbon composite as peroxymonosulfate activator and regenerable adsorbent via sulfate radical-mediated oxidation processes.  

Science.gov (United States)

Magnetic activated carbon composite (CuFe2O4/AC, MACC) was prepared by a co-precipitation-calcination method. The MACC consisted of porous micro-particle morphology with homogeneously distributed CuFe2O4 and possessed high magnetic saturation moment (8.1emug(-1)). The performance of MACC was evaluated as catalyst and regenerable adsorbent via peroxymonosulfate (PMS, Oxone(®)) activation for methylene blue (MB) removal. Optimum CuFe2O4/AC w/w ratio was 1:1.5 giving excellent performance and can be reused for at least 3 cycles. The presence of common inorganic ions, namely Cl(-) and NO3(-) did not exert significant influence on MB degradation but humic acid decreased the MB degradation rate. As a regenerable adsorbent, negligible difference in regeneration efficiency was observed when a higher Oxone(®) dosage was employed but a better efficiency was obtained at a lower MACC loading. The factors hindering complete MACC regeneration are MB adsorption irreversibility and AC surface modification by PMS making it less favorable for subsequent MB adsorption. With an additional mild heat treatment (150°C) after regeneration, 82% of the active sites were successfully regenerated. A kinetic model incorporating simultaneous first-order desorption, second-order adsorption and pseudo-first order degradation processes was numerically-solved to describe the rate of regeneration. The regeneration rate increased linearly with increasing Oxone(®):MACC ratio. The MACC could potentially serve as a catalyst for PMS activation and regenerable adsorbent. PMID:25463211

Oh, Wen-Da; Lua, Shun-Kuang; Dong, Zhili; Lim, Teik-Thye

2015-03-01

66

Thermal and sputtered aluminum oxide coatings for high temperature electrical insulation  

Science.gov (United States)

Aluminum oxide coatings have been investigated as electrically insulating layers for mounting thin film Pt-Pt/Rh thermocouples on gas turbine blade and vane alloys (MAR M200 + Hf and MAR M509). Thermal oxides were grown directly onto NiCoCrAlY and FeCrAlY coatings on these alloys at temperature between 1300 and 1400 K in oxygen partial pressures 10 to the -7th to 2 x 10 to the 4th Pa. Although these thermal oxides exhibited good adherence, analytical characterizations using electron and optical microscopy, as well as X-ray photoelectron spectroscopy showed that they had defects and impurities which limited their insulating ability. The insulating quality of the coating was greatly improved however by reactively sputtering an aluminum oxide film over the thermal oxide. Results are presented on the electrical performance of the 2-5 micron thick composite layers for temperatures up to 1300 K.

Kreider, K. G.; Semancik, S.

1985-01-01

67

Preparation of composites immobilizing highly selective adsorbents and their application to the separation of nuclides  

International Nuclear Information System (INIS)

Radionuclides in high-level liquid waste are classified into four groups such as transuranic elements (TRU) group, technetium - platinum group, strontium - cesium group, and others group. Cesium showed high adsorption selectivity to AMP [(NH4)3PO412MoO33H2O], AWP [(NH4)3PO412WO33H2O], and KNiFC(K2-xNix/2[NiFe(CN)6]nH2O). These inorganic ion exchangers with selectivity of cesium are possible to be supported by porous materials and to be immobilized by polymer. Some examples (AMP/Al2O3, AMP/alginate, and KNiFC/zeolite) are shown in this paper. KCuFC/alginate can adsorb Pd into KCuFC, Ru into alginate, but can not adsorb Rh. Accordingly, platinum metals (Pd, Ru and Rh) are separated by it. Pd, Ru and Rh in their mixed solution are mutually separated by using Cyanex 302/alginate and chromatography. Eu and Am adsorbed by Cyanex 301-alginate acid gel microcapsule were separated by gradient elution. Then, 98.8% of Eu and 91.3% of Am were eluted at pH 2 and pH 1, respectively. (S.Y.)

68

A study on the adsorption of sea water constituents onto the titanium-activated carbon composite adsorbent by spark source mass spectrometry  

International Nuclear Information System (INIS)

Both before and after adsorption of uranium from sea water, the concentrations of various elements on titanium-activated carbon composite adsorbent were determined by spark source mass spectrometry. From the results, the behaviors of sea water constituents in uranium adsorption process were discussed. Adsorptivity of the adsorbent for sea water constituents was evaluated by concentration factors which were calculated from element concentrations in the adsorbent and sea water. The order of adsorptivity for sea water constituents was as follows: alkali metals, halogens, sulphur < boron, alkaline earth metals < phosphor, arsenic < transition metals, uranium. (author)

69

Layered double hydroxide-carbon dot composite: high-performance adsorbent for removal of anionic organic dye.  

Science.gov (United States)

It would be of significance to design a green composite for efficient removal of contaminants. Herein, we fabricated a facile and environmentally friendly composite via direct assembly of surface passivated carbon dots with abundant oxygen-containing functional groups on the surface of the positively charged layered double hydroxide (LDH). The resulting LDH-carbon dot composites were characterized by X-ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy, high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), and N2 adsorption-desorption technique. The adsorption performances of the resulting LDH-carbon dot composites were evaluated for the removal of anionic methyl blue dye. Taking advantage of the combined benefits of LDH and carbon dots, the as-prepared composites exhibited high uptake capability of methyl blue (185 mg/g). The adsorption behavior of this new adsorbent fitted well with Langmuir isotherm and the pseudo-second-order kinetic model. The reasons for the excellent adsorption capacity of methyl blue on the surface of the LDH-carbon dot hybrid were further discussed. A probable mechanism was speculated to involve the cooperative contributions of hydrogen bonding between methyl blue and carbon dots and electrostatic attraction between methyl blue and LDH, in the adsorption process. This work is anticipated to open up new possibilities in fabricating LDH-carbon dot materials in dealing with anionic dye pollutants. PMID:25313875

Zhang, Manlin; Yao, Qingfeng; Lu, Chao; Li, Zenghe; Wang, Wenxing

2014-11-26

70

Oxide coatings on flexible substrates for electrochromic applications  

Science.gov (United States)

One of the most studied classes of materials in the modern microelectronic devices are the metal oxides. There are different metal oxide films, such as electrodes, charge injecting and electrochromic coatings for displays or "smart" windows applications. This paper aims to describe the recent achievements for oxide coating deposition for flexible electrochromic displays. Although many deposition methods for production of such films have been developed, some of the achievements in the field of RF sputtering of transparent electrodes from indium-tin oxide on low-cost polyethyleneterephthalate substrate are presented. Attention is paid on some critical issues, such as films electro-optical parameters (sheet resistance, transparency in the visible range), adhesion, degradation due to stress and patterning ability.

Aleksandrova, M.

2014-11-01

71

Method of forming oxide coatings. [for solar collector heating panels  

Science.gov (United States)

This invention is concerned with an improved plating process for covering a substrate with a black metal oxide film. The invention is particularly directed to making a heating panel for a solar collector. A compound is electrodeposited from an aqueous solution containing cobalt metal salts onto a metal substrate. This compound is converted during plating into a black, highly absorbing oxide coating which contains hydrated oxides. This is achieved by the inclusion of an oxidizing agent in the plating bath. The inclusion of an oxidizing agent in the plating bath is contrary to standard electroplating practice. The hydrated oxides are converted to oxides by treatment in a hot bath, such as boiling water. An oxidizing agent may be added to the hot liquid treating bath.

Mcdonald, G. E. (inventor)

1983-01-01

72

Variation in the composition and partitioning of adsorbed cations at a brine-contaminated crude oil production facility in southeastern Louisiana, USA  

International Nuclear Information System (INIS)

The first geological materials impacted by oil field wastes released into near-surface environments in southern Louisiana, USA, are typically clays and silts. Clay minerals within these siliciclastic sediments have the potential for altering the composition of produced water wastes through cation exchange. The general relations between the composition of adsorbed cations and interstitial water salinity in brine-contaminated samples from a site in southeastern Louisiana are consistent with previous studies of multicomponent exchange in groundwater systems of varying salinity. The divalent cations Ca and Mg dominate as adsorbed cations at low salinities (<1200 mg/L), but Na is dominant at moderate to high salinities (up to 53,000 mg/L). The change in the proportions of adsorbed cations is a non-linear function of salinity, and the transition from Ca-dominated adsorption to Na-dominated adsorption occurs over a narrow range of salinities. Calculated interstitial water compositions, assuming exchange equilibrium, are consistent with the source of contamination being produced waters having Na as the dominant dissolved cation, followed by Ca, rather than some other type of saline waste. The calculated partitioning for Ba indicates that in low to moderate salinity pore waters, Ba, and by extension Ra, are nearly quantitatively adsorbed on the clays and would be of low mobility in a physically active groundwater system. However, at the elevated salinities typical of many prode elevated salinities typical of many produced waters, Ba and Ra are not preferentially adsorbed

73

EIS study of nano crystalline Ni-cerium oxide coating electrodeposition mechanism  

Energy Technology Data Exchange (ETDEWEB)

Research highlights: > In this study a new procedure was used for electrodeposition of Ni-cerium oxide amorphous-nano crystalline composite coatings. The innovation of this method is that the metal and oxides are deposited simultaneously on the samples from the plating bath solution containing Ni ions and Ce ions with no powder added. - Abstract: In this study a novel procedure was used for the electrodeposition of Ni-cerium oxide nano crystalline composite coatings. The novelty of this method lies in the fact that the metal and the oxide are both deposited simultaneously on the substrate, directly from the plating bath containing Ni and Ce ions with no oxide powder addition. Electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) were used to study the mechanisms of Ni-CeO{sub 2} nanocomposite coating deposition. The results indicated that the morphology of Ni-cerium oxide coatings varied based on the Ni:Ce ion ratio. When this ratio exceeds 100, sporadic distribution of cerium oxide in the Ni matrix occurred. On the other hand, when the aforementioned ratio was less than 100, it was found that Ni species were dispersed in a continuous film of cerium oxide. Furthermore, it was observed that Ni in Ni-cerium oxide composite coating was nanocrystalline, while cerium oxide was amorphous. Introduction of the cerium ions to the plating bath resulted in the reduction of the Ni grains average size.

Hasannejad, H. [Department of Materials Science and Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Shahrabi, T., E-mail: Tshahrabi34@modares.ac.ir [Department of Materials Science and Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Jafarian, M. [Department of Chemistry, K.N. Toosi University of Technology, P.O. Box 15875-4416, Tehran (Iran, Islamic Republic of); Rouhaghdam, A. Sabour [Department of Materials Science and Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of)

2011-02-03

74

Carboxyl-functionalized mesoporous silica–carbon composites as highly efficient adsorbents in liquid phase  

Digital Repository Infrastructure Vision for European Research (DRIVER)

[EN] Mesoporous silica–carbon composites functionalized with acidic oxygen groups were prepared by oxidation of a layer of carbon deposited inside the silica pores. The synthesis procedure involved the following steps: (a) removal of the silica surfactant, (b) impregnation of the silica pores with a carbon precursor, (c) carbonization and (d) oxidation with ammonium persulfate. The resulting silica–carbon composites contained around 25–30 wt.% of carbonaceous matter with a high density ...

Valle Vigo?n, Patricia; Sevilla Soli?s, Marta; Fuertes Arias, Antonio Benito

2013-01-01

75

Preparation of Surface Adsorbed and Impregnated Multi-walled Carbon Nanotube/Nylon-6 Nanofiber Composites and Investigation of their Gas Sensing Ability  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 several months without precipitation. A MWCNTs/Nylon-6 nanofiber composite based chemical sensor has demonstrated its responsiveness towards a wide range of solvent vapours at room tempera...

Velmurugan Thavasi; Lala, Neeta L.; Seeram Ramakrishna

2009-01-01

76

Conductivity of copper phthalocyanine-polystyrene composite films in the presence of adsorbed oxygen  

Science.gov (United States)

The electrical conductivity and adsorption-resistive response to nitrogen dioxide of composite films containing copper phthalocyanine nanoparticles dispersed into the polystyrene matrix are investigated experimentally. The results are analyzed using the two-level model of hopping conductivity. The contributions to the conductivity from intrinsic and impurity localization centers are singled out, and the concentrations of the localization centers in copper phthalocyanines free of impurities as well as the electron localization radii in impurity and intrinsic states are determined.

Pochtennyi, A. E.; Misevich, A. V.; Dolgii, V. K.

2014-09-01

77

Novel low density granular adsorbents - properties of a composite matrix from zeolitisation of vermiculite.  

Science.gov (United States)

This paper reports the preparation and properties of a new low density granular absorbent material based on a zeolite/vermiculite composite. The composite prepared addresses a number of important issues relating to the use of zeolites in environmental and waste management applications. The material prepared has large particle size due to binderless adhesion of zeolite crystals within the protective lamellar matrix provided by the vermiculite granule. Additionally, the porous nature of new material ensures that it outperforms natural zeolite grains in ion-exchange tests. The material was shown to have a low bulk density (0.75 g cm(-3)) adding the benefit that the majority of grains float on water for over 15 h. The conclusion of the study is that the use of composite matrices enable the preparation of materials which show the physical properties of the host, (e.g., granular and low density), whilst maintaining the powder-like properties (e.g., high ion-exchange and small crystal size) of the active component. The resulting material can be easily handled and separated from aqueous waste streams using either flotation or exploiting its granular nature. PMID:17368511

Johnson, Christopher D; Worrall, Fred

2007-06-01

78

Neutron reflectivity of adsorbed water-soluble block copolymers at the air/water interface: The effects of composition and molecular weight  

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We have used neutron reflection to follow the effects of composition and molecular weight on the structure of layers of poly(2-(dimethylamino)ethyl methacrylate-block-methyl methacrylate copolymer (poly(DMAEMA-b-MMA)) adsorbed at the air/water interface. We had previously shown that for a 70% DMAEMA copolymer of Mn about 10K at a pH of 7.5 there is a surface phase transition from a layer about 20 Å thick to one about 40 Å thick and that the adsorbed layer at the higher concentration has a l...

An, Sw; Thomas, Rk; Baines, Fl; Billingham, Nc; Armes, Sp; Penfold, J.

1998-01-01

79

XPS characterisation of plasma treated and zinc oxide coated PET  

International Nuclear Information System (INIS)

At first, X-ray photoelectron spectroscopy (XPS) analyses of reference and carbon dioxide plasma treated polyethylene terephthalate (PET) were carried out. Significant chemical modifications were outlined in the treated PET surface in comparison with the reference one. The formation of new oxygenated groups was evidenced. These modifications heighten the level of interactions between the polymer substrate and the deposited coating. In a second stage, zinc oxide thin films were elaborated by r.f. magnetron sputtering from a ceramic target and with a reactive gas (mixture of argon-1% oxygen) under optimised conditions on CO2 plasma treated PET. The interfacial chemistry between the plasma treated PET and the zinc oxide was also studied by XPS. The line shape changes in the high-resolution core level spectra of carbon C1s, oxygen O1s, and zinc (Zn2p3/2, Zn3p), with the progressive deposition of zinc oxide coatings being recorded. The obtained spectra were fitted to mixed Gaussian-Lorentzian components using XPS CASA software. An interaction scheme between the zinc oxide thin layer and its polymer substrate, in the first stage of deposition, was proposed and checked by corroborating the findings of the different XPS spectra and their decompositions. It suggests the formation of Zn-O-C complexes at the interface, which are promoted by an electron transfer from zinc to oxygen in oxygenated species, mainly alcohol groups, generated by the CO2 plasma tregenerated by the CO2 plasma treatment of PET.

80

Adsorption of Th4+, U6+, Cd2+, and Ni2+ from aqueous solution by a novel modified polyacrylonitrile composite nanofiber adsorbent prepared by electrospinning  

Science.gov (United States)

In this study, SiO2 nanoparticles were modified by 3-aminopropyltriethoxysilane (APTES) and then applied to prepare a novel polyacrylonitrile (PAN) composite nanofiber adsorbent by the electrospinning method. In addition, the adsorbent was characterized by SEM, BET, and FTIR analyses. Then the effects of pH, SiO2 and APTES content, adsorbent dosage, contact time and temperature were investigated. Moreover, adsorption experiments were carried out with initial concentrations in the range of 30-500 mg L-1 and the adsorbent affinity for metal ions was in order of Th4+ > U6+ > Cd2+ > Ni2+. Furthermore, it was observed that the optimum pH for adsorption was different for each metal. Some isotherm and kinetic models were applied to analyze the experimental data, among which the Langmuir and pseudo-second order models were better than the others. The regeneration study showed that the adsorbent could be used for industrial processes repeatedly without any significant reduction in its adsorption capacity. Based on the Langmuir model, the maximum adsorption capacity of Th4+, U6+, Cd2+, and Ni2+ at 45 °C was 249.4, 193.1, 69.5 and 138.7 mg g-1, respectively. Besides, the calculated thermodynamic parameters showed an endothermic as well as chemical nature through the adsorption process.

Dastbaz, Abolfazl.; Keshtkar, Ali Reza.

2014-02-01

 
 
 
 
81

Adsorption of Th4+, U6+, Cd2+, and Ni2+ from aqueous solution by a novel modified polyacrylonitrile composite nanofiber adsorbent prepared by electrospinning  

International Nuclear Information System (INIS)

In this study, SiO2 nanoparticles were modified by 3-aminopropyltriethoxysilane (APTES) and then applied to prepare a novel polyacrylonitrile (PAN) composite nanofiber adsorbent by the electrospinning method. In addition, the adsorbent was characterized by SEM, BET, and FTIR analyses. Then the effects of pH, SiO2 and APTES content, adsorbent dosage, contact time and temperature were investigated. Moreover, adsorption experiments were carried out with initial concentrations in the range of 30–500 mg L?1 and the adsorbent affinity for metal ions was in order of Th4+ > U6+ > Cd2+ > Ni2+. Furthermore, it was observed that the optimum pH for adsorption was different for each metal. Some isotherm and kinetic models were applied to analyze the experimental data, among which the Langmuir and pseudo-second order models were better than the others. The regeneration study showed that the adsorbent could be used for industrial processes repeatedly without any significant reduction in its adsorption capacity. Based on the Langmuir model, the maximum adsorption capacity of Th4+, U6+, Cd2+, and Ni2+ at 45 °C was 249.4, 193.1, 69.5 and 138.7 mg g?1, respectively. Besides, the calculated thermodynamic parameters showed an endothermic as well as chemical nature through the adsorption process

82

Spark-anodic oxide coatings formed on Al and Ti alloys in tungstate-containing phosphate-vanadate baths  

International Nuclear Information System (INIS)

The oxide coatings, the external layer whereof is enriched by P, V, W, are formed on the aluminium and titanium alloys by the method of the anodic-spark oxidation in the aqueous electrolytes, containing the 45.9 g/l NaH2PO4·2H2O, 15 g/l NaVO3·2H2O and various concentrations of Na2WO4·2H2O. The composition of the coatings is studied by the methods of the laser mass-spectrometry and microprobe analysis, and the state of the phosphate groups - by the NMR spectroscopy on the 31P nuclei. The supposition is made on the interrelation between the elements in the coatings and composition, the concentration of the vanadium-tungstate phosphates and vanadium tungstates in the solution

83

Laccase immobilized on a PAN/adsorbents composite nanofibrous membrane for catechol treatment by a biocatalysis/adsorption process.  

Science.gov (United States)

The treatment of catechol via biocatalysis and adsorption with a commercial laccase immobilized on polyacrylonitrile/montmorillonite/graphene oxide (PAN/MMT/GO) composite nanofibers was evaluated with a homemade nanofibrous membrane reactor. The properties in this process of the immobilized laccase on PAN, PAN/MMT as well as PAN/MMT/GO with different weight ratios of MMT and GO were investigated. These membranes were successfully applied for removal of catechol from an aqueous solution. Scanning electron microscope images revealed different morphologies of the enzyme aggregates on different supports. After incorporation of MMT or MMT/GO, the optimum pH showed an alkaline shift to 4, compared to 3.5 for laccase immobilized on pure PAN nanofibers. The optimum temperature was at 55 °C for all the immobilized enzymes. Besides, the addition of GO improved the operational stability and storage stability. A 39% ± 2.23% chemical oxygen demand (COD) removal from the catechol aqueous solution was achieved. Experimental results suggested that laccase, PAN, adsorbent nanoparticles (MMT/GO) can be combined together for catechol treatment in industrial applications. PMID:24651612

Wang, Qingqing; Cui, Jing; Li, Guohui; Zhang, Jinning; Li, Dawei; Huang, Fenglin; Wei, Qufu

2014-01-01

84

Laccase Immobilized on a PAN/Adsorbents Composite Nanofibrous Membrane for Catechol Treatment by a Biocatalysis/Adsorption Process  

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Full Text Available The treatment of catechol via biocatalysis and adsorption with a commercial laccase immobilized on polyacrylonitrile/montmorillonite/graphene oxide (PAN/MMT/GO composite nanofibers was evaluated with a homemade nanofibrous membrane reactor. The properties in this process of the immobilized laccase on PAN, PAN/MMT as well as PAN/MMT/GO with different weight ratios of MMT and GO were investigated. These membranes were successfully applied for removal of catechol from an aqueous solution. Scanning electron microscope images revealed different morphologies of the enzyme aggregates on different supports. After incorporation of MMT or MMT/GO, the optimum pH showed an alkaline shift to 4, compared to 3.5 for laccase immobilized on pure PAN nanofibers. The optimum temperature was at 55 °C for all the immobilized enzymes. Besides, the addition of GO improved the operational stability and storage stability. A 39% ± 2.23% chemical oxygen demand (COD removal from the catechol aqueous solution was achieved. Experimental results suggested that laccase, PAN, adsorbent nanoparticles (MMT/GO can be combined together for catechol treatment in industrial applications.

Qingqing Wang

2014-03-01

85

Removal of transition metal ions from aqueous solutions by adsorption onto a novel silica gel matrix composite adsorbent  

International Nuclear Information System (INIS)

This paper presented the synthesis of a novel composite adsorbent silica gel microspheres encapsulated with 5-sulfosalicylic acid functionalized polystyrene (SG-PS-azo-SSA). It was characterized by titration method, FT-IR (Fourier transform infrared spectrometer), SEM (scanning electron microscope), EDXAS (energy dispersive X-ray analysis system), etc. SG-PS-azo-SSA has been used to investigate the adsorption of Mn(II), Fe(III), Co(II), Ni(II), Zn(II), Cd(II), Hg(II), Pd(II), Cu(II), Ag(I) and Au(III) from aqueous solutions. The research results revealed that SG-PS-azo-SSA has the better adsorption capacity for Cu(II), Ag(I) and Au(III). Langmuir and Freundlich isotherm models were applied to analyze the experimental data and the adsorption of Cu(II), Ag(I) and Au(III) on SG-PS-azo-SSA fitted well to the Langmuir isotherm equation. The obtained maximum adsorption capacity for Cu(II), Ag(I), and Au(III) is 0.472 mmol/g, 0.822 mmol/g and 0.810 mmol/g, respectively. Thus, silica gel encapsulated by 5-sulfosalicyclic acid functionalized polystyrene (SG-PS-azo-SSA) is favorable and useful for the removal of Cu(II), Ag(I) and Au(III) metal ions.

86

The Impact of Mn Oxide Coatings on Zn Distribution  

International Nuclear Information System (INIS)

Zinc sorption to hydrous manganese oxide (HMO)-coated clay was investigated macroscopically, kinetically, and spectroscopically. Adsorption edges and isotherms revealed that the affinity and capacity of the HMO-coated montmorillonite was greater than that of montmorillonite, and when normalized to the oxide present, the coatings behaved similarly to the discrete Mn oxide. Over two pH conditions, 5 and 6, a linear relationship was observed for the isotherms; further analysis with X-ray absorption spectroscopy (XAS) resulted in one type of sorption configuration as a function of loading and ionic strength at pH 5. However, at a surface loading of 10-3 molZn gHMO-coated clay-1 source when the pH increased from 5 to 7, the first shell distance decreased slightly, while the atoms and coordination numbers remained the same; this change may be attributed to an increase in electrostatic interactions. After a contact time of 4 months where an additional 60% of the sites become occupied, the slower sorption process was modeled as intraparticle surface diffusion. Best fit diffusivities ranged from 10-18 to 10-17 cm2/s, where a slower process was observed for the coated surface as compared to the discrete oxide. Interestingly, the porosity of the Mn oxide coating appears to be influenced by the substrate during its growth, as its increase and shift to a smaller pore size distribution resulted a smaller pore size distribution resulted in a diffusivity between that observed for discrete HMO and montmorillonite

87

Lead isotopes in iron and manganese oxide coatings and their use as an exploration guide for concealed mineralization  

Science.gov (United States)

Lead isotopes from Fe and Mn oxides that coat stream pebbles from around the Mount Emmons porphyry molybdenum deposit in Colorado were studied to assess the feasibility of using Pb isotopes to detect concealed mineral deposits. The Fe/Mn oxide coatings were analyzed to determine their elemental concentrations using ICP-AES. The Pb isotope compositions of solutions from a selected suite of samples were measured, using both thermal ionization and ICP mass spectrometry, to compare results determined by the two analytical methods. Heavy mineral concentrates from the same sites were also analyzed to compare the Pb isotope compositions of the Fe/Mn coatings with those found in panned concentrates. The Fe/Mn and 206Pb/204Pb ratios of the oxide coatings are related to the lithology of the host rocks; Fe/Mn oxide coatings on pebbles of black shale have higher Fe/Mn values than do the coatings on either sandstone or igneous rocks. The shale host rocks have a more radiogenic signature (e.g. higher 206Pb/ 204Pb) than the sandstone or igneous host rocks. The Pb isotope data from sandstone and igneous hosts can detect concealed mineralized rock on both a regional and local scale, even though there are contributions from: (1) metals from the main-stage molybdenite ore deposit; (2) metals from the phyllic alteration zone which has a more radiogenic Pb isotope signature reflecting hydrothermal leaching of Pb from the Mancos Shale; (3) Pb-rich base metal veins with a highly variable Pb isotope signature; and (4) sedimentary country rocks which have a more radiogenic Pb isotope signature. An investigation of within-stream variation shows that the Pb isotope signature of the molybdenite ore zone is retained in the Fe/Mn oxide coatings and is not camouflaged by contributions from Pb-rich base-metal veins that crop out upstream. In another traverse, the Pb isotope data from Fe/Mn oxide coatings reflect a complex mixing of Pb from the molybdenite ore zone and its hornfels margin, Pb-rich base-metal veins, and sedimentary country rocks. Stream-sediment anomalies detected using oxalic acid leaches can be evaluated using Pb isotope analysesof selected geochemical anomalies. Such an evaluation procedure, given regional target Pb isotope signatures for concealed mineralization, can greatly reduce the cost of exploration for undiscovered ore deposits concealed beneath barren overburden. Lead isotope measurements on aliquots of the same solutions showed that ICP-MS determinations are of low precision and vary non-systematically when compared with the Pb isotope values of the higher precision thermal ionization method. These variations and lower precision of the ICP-MS measurements are attributed to matrix effects. ?? 1992.

Gulson, B.L.; Church, S.E.; Mizon, K.J.; Meier, A.L.

1992-01-01

88

Performance comparison of dye-sensitized solar cells by using different metal oxide- coated TiO2 as the photoanode  

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In order to increase the conversion efficiency of dye-sensitized solar cells, TiO2 photoanode surface is often covered with a metal oxide layer to form a core-shell composite structure. Different metal oxide coating on TiO2 as composite photoanodes can affect the cell efficiency variously. However, there still lacks the crosswise comparison among the effects of different metal oxides on TiO2 photoanode. In this study, TiO2 was coated with Al2O3, CaO, ZnO, MgO, Fe2O3 or Bi2O3 separately by liq...

Sun Xuhui; Chang Xinglan; Tuo Wanquan; Wang Dong; Li Kefei

2014-01-01

89

Sol-gel prepared active ternary oxide coating on titanium in cathodic protection  

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The characteristics of a ternary oxide coating, on titanium, which consisted of TiO2, RuO2 and IrO2 in the molar ratio 0.6:0.3:0.1, calculated on the metal atom, were investigated for potential application for cathodic protection in a seawater environment. The oxide coatings on titanium were prepared by the sol gel procedure from a mixture of inorganic oxide sols, which were obtained by forced hydrolysis of metal chlorides. The morphology of the coating was examined by scanning electron micro...

Panic, Vladimir V.; Nikolic, Branislav Z.

2007-01-01

90

Activity of Trypsin Adsorbed on Temperature and pH-Responsive Micron-Sized PS/P(NIPAM-MAA-MBAAm) Composite Polymer Particles  

Science.gov (United States)

Micron-sized polystyrene (PS) seed particles were prepared by dispersion polymerization of styrene in ethanol-water media. Seeded copolymerization of N-isopropyl acrylamide (NIPAM), methacrylic acid (MAA) and N,N`-methylene-bis-acrylamide (MBAAm) was then carried out in presence of PS seed particles. The produced PS/P(NIPAM-MAA-MBAAm) composite polymer particles exhibited volume phase transition to small changes in temperature and pH, respectively. Specific activities of trypsin aqueous solution (free trypsin) and trypsin in presence of PS seed and composite polymer particles were measured under identical conditions. Relative study suggested that trypsin adsorbed on PS/P(NIPAM-MAA-MBAAm) composite polymer particles retained their native conformation.

Ashraful Alam, M.; Jalil Miah, M. A.; Ahmad, Hasan

91

Studies on yttrium oxide coatings for corrosion protection against molten uranium  

International Nuclear Information System (INIS)

Yttrium oxide is resistant to corrosion by molten uranium and its alloys. Yttrium oxide is recommended as a protective oxide layer on graphite and metal components used for melting and processing uranium and its alloys. This paper presents studies on the efficacy of plasma sprayed yttrium oxide coatings for barrier applications against molten uranium

92

Formulation of an alginate-vineyard pruning waste composite as a new eco-friendly adsorbent to remove micronutrients from agroindustrial effluents.  

Science.gov (United States)

The cellulosic fraction of vineyard pruning waste (free of hemicellulosic sugars) was entrapped in calcium alginate beads and evaluated as an eco-friendly adsorbent for the removal of different nutrients and micronutrients (Mg, P, Zn, K, N-NH4, SO4, TN, TC and PO4) from an agroindustrial effluent (winery wastewater). Batch adsorption studies were performed by varying the amounts of cellulosic adsorbent (0.5-2%), sodium alginate (1-5%) and calcium chloride (0.05-0.9M) included in the biocomposite. The optimal formulation of the adsorbent composite varied depending on the target contaminant. Thus, for the adsorption of cationic contaminants (Mg, Zn, K, N-NH4 and TN), the best mixture comprised 5% sodium alginate, 0.05M calcium chloride and 0.5% cellulosic vineyard pruning waste, whereas for removal of anionic compounds (P, SO4 and PO4), the optimal mixture comprised 1% sodium alginate, 0.9M calcium chloride and 0.5% cellulosic vineyard pruning waste. To remove TC from the winery wastewater, the optimal mixture comprised 3% of sodium alginate, 0.475M calcium chloride and 0.5% cellulosic vineyard pruning waste. PMID:24997896

Vecino, X; Devesa-Rey, R; Moldes, A B; Cruz, J M

2014-09-01

93

THE COMPOSITION AND STRUCTURE OF SODIUM DODECYL-SULFATE DODECANOL MIXTURES ADSORBED AT THE AIR-WATER-INTERFACE - A NEUTRON REFLECTION STUDY  

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Neutron reflection has been used to study the composition of layers of sodium dodecyl sulfate (SDS) and dodecanol mixtures adsorbed at the air/water interface. Saturation of the surface by dodecanol at a 6.7 mM SDS concentration occurs when the bulk dodecanol concentration is about four times the solubility of dodecanol in pure water, indicating that even below the cmc dodecanol is solubilized by SDS. At a fixed dodecanol/SDS ratio the adsorption of dodecanol passes through a maximum at about...

Lu, J.; Purcell, I.; Lee, E.; Simister, E.; Thomas, R.; Rennie, A.; Penfold, J.

1995-01-01

94

Insulating characteristics and hydrogen absorption of aluminum oxide coatings deposited by RF magnetron sputtering  

International Nuclear Information System (INIS)

Aluminum oxide with high resistivity and tritium permeation resistance is considered as a promising candidate functional material for ITER. In this study, aluminum oxide coatings were prepared onto the China Low Activation Martensitic (CLAM) steel substrates via RF magnetron sputtering. The structure and the surface morphologies of the coatings prepared at various O2/Ar ratios were characterized via grazing incidence Xray diffraction, Raman spectroscopy and atomic force microscopy. The Janume resistivities of the coatings were measured. The hydrogen absorption of the coating samples was also studied. The results show that the aluminum oxide coatings prepared at O2/Ar ratios of 0.1 and 0.5 are amorphous, while the aluminum oxide coating prepared at an O2/Ar ratio of 0.4 h as a poor ? phase crystalline structure. The roughness average and the particle size of the coatings prepared at O2/Ar ratios of 0.1 and 0.4 are smaller than those prepared at an O2/Ar ratio of 0.5. The Janume resistivities of the coatings prepared at various O2/Ar ratios all exceed 2.7 x 1014 ?·cm, and the coating prepared at an O2/Ar ratio of 0.4 h as the largest resistivity, reaching 2.1 x 1015 ?·cm. The hydrogen absorption of the coating prepared at an O2/Ar ratio of 0.5 is the smallest. The electrical insulation and hydrogen absorption properties of the aluminum oxide coatings are afof the aluminum oxide coatings are affected significantly by O2/Ar ratios. (authors)

95

Preparation of Surface Adsorbed and Impregnated Multi-walled Carbon Nanotube/Nylon-6 Nanofiber Composites and Investigation of their Gas Sensing Ability  

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Full Text Available 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 several months without precipitation. A MWCNTs/Nylon-6 nanofiber composite based chemical sensor has demonstrated its responsiveness towards a wide range of solvent vapours at room temperature and only mg quantities of MWCNTs were expended. The large surface area and porous nature of the electrospun Nylon-6/MWCNT nanofibers facilitates greater analyte permeability. The experimental analysis has indicated that the dipole moment, functional group and vapour pressure of the analytes determine the magnitude of the responsiveness.

Velmurugan Thavasi

2009-01-01

96

Rare earth elements and neodymium isotopes in ferromanganese oxide coatings of Cenozoic foraminifera from the Atlantic Ocean  

International Nuclear Information System (INIS)

An evaluation has been made of the method of establishing the REE contents and patterns and Nd isotopic compositions of sea water over Cenozoic time from their record in the FeMn-oxide coatings of foraminiferal calcite. Using 0-60 Ma samples from the Rio Grande Rise (DSDP Site 357) it has been established that the REE contents of the coatings are generally similar to those of recent samples. However, in the Cenozoic samples the surface coatings have been diagenetically modified under suboxic conditions resulting in a distinctly different REE pattern although the original 143Nd/144Nd ratios appear to have been preserved. The Nd isotopic curve for Cenozoic sea water in the S. Atlantic shows clear temporal trends, although these are not so extreme as to show 143Nd/144Nd ratios outside the range observed in modern sea water. With the principal exception of the oldest samples there is an approximate inverse relationship between the Nd and Sr isotopic compositions of foraminifera. The Nd isotopic curve appears to be a potentially useful tracer of ocean palaeochemistry. (author)

97

Features of microarc oxidation coatings formation technology in slurry electrolytes  

Science.gov (United States)

A group of electrolytes composed of different powders entered into electrolyte presents a separate direction in microarc oxidation (MAO) technology. This group of electrolytes is most complex and however it has not been sufficiently studied yet. This paper shows that addition of powders of different nature into electrolyte influences both on properties of obtained coatings and on speed of their formation. The MAO-coatings formed in similar electrolytes-suspensions or slurry electrolytes (SE) contain in their composition an essential share of powder material entered into electrolyte as corpuscles of disperse phase (DP). Different nonmetallic combinations are used: oxides, carbides, borides, nitrides of metals and others. The particular conditions of microarc discharge regime (high temperature and pressure in a zone of breakdown) cause a thermolysis of electrolyte together with weighed corpuscles of solid matter, the realization of plasma chemical reactions on oxidizing surface and provide the synthesis of chemical combinations in an oxide matrix. A new composition of slurry electrolyte which allows improving the quality of obtained coatings on the basis of held investigations was developed.

Malyshev, V. N.; Zorin, K. M.

2007-12-01

98

Tungsten bronze-based nuclear waste form ceramics. Part 2: Conversion of granular microporous tungstate-polyacrylonitrile (PAN) composite adsorbents to leach resistant ceramics  

International Nuclear Information System (INIS)

Conversion of a granular molybdenum-doped, hexagonal tungsten bronze (MoW-HTB)-polyacrylonitrile (PAN) composite adsorbent to a leach resistant ceramic waste form capable of immobilizing adsorbed Cs+ and Sr2+ has been achieved by heating in air at temperatures in the range 600-1200 deg. C. Thermal treatment of the Cs- and Sr-loaded composite material at 1000 deg. C was sufficient to invoke a 60% reduction in volume of the composite while still retaining its spherical morphology. Cs-133 MAS NMR studies of this sample suite at 9.4 T and 14.1 T showed that multiple Cs sites are present throughout the entire thermal treatment range. Scanning electron microscopy investigations of the phase assemblages resulting from thermal treatment demonstrated that the full complement of Cs, and the majority of Sr, partitions into HTB phases (A0.16-0.3MO3; A = Cs+, Sr2+ and Na+; M = Mo, W). The potentially reducing conditions resulting from the removal of the PAN matrix or the presence of high concentrations of Na+ relative to either Cs+ or Sr2+ does not retard the formation of the high temperature HTB phases. The fraction of Cs+ and Sr2+ leached from the tungstate phase assemblages was superior or comparable with cesium hollandite (Cs0.8Ba0.4Ti8O18; f = ?8 x 10-5; rate = -4 g/m; rate = -4 g/m2/day) and strontium titanate (SrTiO3; f = 3.1 x 10-3; rate = 2.63 x 10-4 g/m2/day), respectively, using a modified PCT test in Millipore water at 90 deg. C. Furthermore, where aggressive leaching conditions were employed (0.1 M HNO3; 150 deg. C; 4 days), the tungstate phase assemblages displayed leach resistance almost two orders of magnitude greater than the reference phases

99

Electrochemical Behavior of Chemical Vapor Deposited Protective Aluminum Oxide Coatings on Ti6242 Titanium Alloy  

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The electrochemical behavior at room temperature in a neutral sodium chloride aqueous solution of four types of metallorganic chemical vapor deposited aluminum oxide coatings on commercial Ti6242 titanium alloy was investigated. Polarization and electrochemical impedance curves revealed that porosity free, amorphous alumina coatings provide a two order of magnitude improvement of the corrosion resistance with regard to the bare alloy. Crystallized alumina as well as amorphous AlO(OH) only sli...

Boisier, Gre?gory; Raciulete, Monica; Same?lor, Diane; Pe?be?re, Nadine; Gleizes, Alain; Vahlas, Constantin

2008-01-01

100

Radium, thorium, and actinium extraction from seawater using an improved manganese-oxide-coated fiber  

International Nuclear Information System (INIS)

Laboratory experiments were conducted to determine the efficiency with which improved manganese-oxide-coated acrylic fibers extract radium, thorium, and actinium from seawater. Tests were made using surface seawater spiked with 227Ac, 227Th and 223Ra. For sample volumes of approximately 30 liters and flow rates up to 0.5 liters per minute, radium and actinium are removed quantitatively. Approximately 80-95% of the thorium is removed under these same conditions. (Auth.)

 
 
 
 
101

Preparation and properties of poly(vinylidene fluoride) nanocomposites blended with graphene oxide coated silica hybrids  

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Graphene oxide coated silica hybirds (SiO2-GO) were fabricated through electrostatic assembly in this work, then blended with poly(vinylidene fluoride) (PVDF) by solution mixing to make PVDF nanocomposites. The interfacial interaction was investigated by scanning electron microscopy (SEM), polarized optical microscopy (POM) and Fourier transform infrared spectroscopy (FTIR). The results showed that the interfacial interaction was enhanced by adding of SiO2-GO and strong hydrogen bonds were ob...

Fu, Q.; Wang, J. C.; Chen, P.; Chen, L.; Wang, K.; Deng, H.; Chen, F.; Zhang, Q.

2012-01-01

102

Heat conductivity of oxide coatings by photothermal radiometry between 293 and 1173 K.  

Science.gov (United States)

Optical generation and optical detection of thermal waves are used to determine the thermal properties of three different oxide coatings on stainless steel substrates at temperatures up to 1173 K. The thermal diffusivities alpha and thermal conductivities k strongly depend on the method of preparation as well as on the environmental conditions during deposition. Our experimental values for alpha and k are generally lower than handbook data for bulk specimens of the same materials. PMID:20539633

Frederikse, H P; Ying, X T

1988-11-15

103

Surface characteristics and electrochemical corrosion behavior of a pre-anodized microarc oxidation coating on titanium alloy.  

Science.gov (United States)

A porous bioactive titania coating on biomedical ? titanium alloy was prepared by pre-anodization followed by micro arc oxidation technology. The effects of pre-anodization on the phase constituent, morphology and electrochemical corrosion behavior of the microarc oxidation coating were investigated. The results show that pre-anodization has less influence on the phase constituent and the surface morphology of the microarc oxidation coating, but improves the inner layer density of the microarc oxidation coating. The decrease of plasma discharge strength due to the presence of the pre-anodized oxide film contributes to the formation of the compact inner layer. The pre-anodized microarc oxidation coating effectively inhibits the penetration of the electrolyte in 0.9% NaCl solution and thus increases the corrosion resistance of the coated titanium alloy in physiological solution. PMID:23910276

Cui, W F; Jin, L; Zhou, L

2013-10-01

104

Rare earth oxide coatings to decrease high temperature degradation of chromia forming alloys  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The addition of small quantities of reactive elements such as rare earths (RE) to chromia or alumina forming alloys improves the high temperature oxidation resistance. Traditionally, these elements are alloying additions or are added as oxides to form a dispersion. The alloys can also be coated with [...] RE oxides. Several methods can be used to coat alloy substrates with RE oxides and the sol-gel process is considered to be quite efficient, as it generates the very small oxide particles. This paper presents the influence of surface coatings of Ce, La, Pr, and Y oxide gels on the oxidation behavior of an Fe-20Cr alloy at 1000 °C. The morphology of the rare earth (RE) oxide coatings varied with the nature of RE. The oxidation rate of RE oxide coated Fe-20Cr was significantly less than that of the uncoated alloy. The extent of influence the RE oxide coating exercised on the oxidation rate decreased in the following order: La, Ce, Pr, Y. The scale formed in the presence of RE oxide was very thin, fine grained and adherent chromia. A direct correlation between rare earth ion radius and the extent of influence on chromia growth rate at 1000 °C was observed.

Stela Maria de Carvalho, Fernandes; Lalgudi Venkataraman, Ramanathan.

2004-03-01

105

Rare earth oxide coatings to decrease high temperature degradation of chromia forming alloys  

Directory of Open Access Journals (Sweden)

Full Text Available The addition of small quantities of reactive elements such as rare earths (RE to chromia or alumina forming alloys improves the high temperature oxidation resistance. Traditionally, these elements are alloying additions or are added as oxides to form a dispersion. The alloys can also be coated with RE oxides. Several methods can be used to coat alloy substrates with RE oxides and the sol-gel process is considered to be quite efficient, as it generates the very small oxide particles. This paper presents the influence of surface coatings of Ce, La, Pr, and Y oxide gels on the oxidation behavior of an Fe-20Cr alloy at 1000 °C. The morphology of the rare earth (RE oxide coatings varied with the nature of RE. The oxidation rate of RE oxide coated Fe-20Cr was significantly less than that of the uncoated alloy. The extent of influence the RE oxide coating exercised on the oxidation rate decreased in the following order: La, Ce, Pr, Y. The scale formed in the presence of RE oxide was very thin, fine grained and adherent chromia. A direct correlation between rare earth ion radius and the extent of influence on chromia growth rate at 1000 °C was observed.

Stela Maria de Carvalho Fernandes

2004-03-01

106

Development of Niobium Oxide Coatings on Sand-Blasted Titanium Alloy Dental Implants  

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Full Text Available The purpose of this study was to use scanning electron microscopy (SEM evaluation to determine the optimal anodizetion conditions needed to generate niobium oxide coatings on titanium alloy dental implant screws. Sand-blasted titanium alloy dental implants were anodized in dilute hydrofluoric acid (HF(aq solution using a Sorensen DLM 300-2 power supply. The HF concentration and anodization time were varied and the resulting implant surfaces were evaluated using a Jeol JSM-5310LV Scanning Electron Microscope to determine the ideal anodization conditions. While HF is necessary to facilitate oxide growth, increasing concentrations resulted in proportionate increases in coating delamination. In a similar manner, a minimum anodization time of 1 hour was necessary for oxide growth but longer times produced more delamination especially at higher HF(aq concentrations. SEM imaging showed that implants anodized for 1 hour in a 0.1% HF(aq aqueous solution had the best results. Anodization can be used to generate niobium oxide coatings on sand-blasted Ti alloy dental implants by balancing the competing factors of oxide growth and coating delamination. It is believed that these oxide coatings have the potential to improve osseointegration relative to untreated dental implants when evaluated in an in vivo study.

Daniel L. Alge

2012-05-01

107

Mechanical analysis of ultrathin oxide coatings on polymer substrates in situ in a scanning electron microscope  

International Nuclear Information System (INIS)

Uniaxial fragmentation tests were carried out in situ in a scanning electron microscope (SEM) on 10-nm-thick silicon oxide coatings deposited by plasma enhanced chemical vapor deposition on poly(ethylene terephthalate). In order to prevent charging effects due to the isolating nature of the oxide surface, an additional conductive gold layer was sputtered onto the coating prior to its tensile loading in the SEM chamber. The gold layer was shown not to affect initiation of tensile failure of the oxide coating, and was used to achieve optimal resolution by eliminating charging effects in the low-strain range. In contrast, in the high strain range, the failure behavior of the oxide coating was found to be modified by the gold layer. It was nevertheless possible to analyze the damage mechanisms of the thin coating without a gold layer due to sufficient crack opening. The coating cohesive strength was found to be equal to 5.1 GPa, and the coating/polymer interfacial strength was found to be equal to 84 MPa using a Weibull size-dependent probability of failure for the oxide, and assuming a perfectly plastic stress transfer between the different layers

108

Cavitation erosion resistance of microarc oxidation coating on aluminium alloy  

Energy Technology Data Exchange (ETDEWEB)

Two ceramic coatings are prepared on 2124 aluminum alloy by microarc oxidation (MAO) technology. To explore the cavitation erosion resistance of the MAO coating, cavitation tests were performed by using a rotating-disk test rig. The mass losses, surface morphologies, chemical compositions and the phase constituents of the samples after cavitation tests were examined by using digital balance, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), respectively. The results indicate that the MAO coatings can extend the incubation period of aluminum alloy, and thus enhance the cavitation erosion resistance as compared to the untreated aluminum alloy samples. After duration of 63 h cavitation test, a lot of erosion pits and the particles in various shapes can be observed on the surfaces of the aluminum alloy samples, while only a few erosion pits are observed on the MAO coatings. Moreover, the mean depths of erosion on the MAO coatings are lower in the first 30 h and are independent on erosion time. The results show that the cavitation erosion of MAO coating is governed by water mechanical impaction, resulting from the effects of brittle fracture of the MAO coating.

Cheng, Feng [School of Mechanical Engineering, Southeast University, Nanjing, 211189 (China); Jiang, Shuyun, E-mail: jiangshy@seu.edu.cn [School of Mechanical Engineering, Southeast University, Nanjing, 211189 (China); Liang, Jun [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China)

2013-09-01

109

Cavitation erosion resistance of microarc oxidation coating on aluminium alloy  

International Nuclear Information System (INIS)

Two ceramic coatings are prepared on 2124 aluminum alloy by microarc oxidation (MAO) technology. To explore the cavitation erosion resistance of the MAO coating, cavitation tests were performed by using a rotating-disk test rig. The mass losses, surface morphologies, chemical compositions and the phase constituents of the samples after cavitation tests were examined by using digital balance, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), respectively. The results indicate that the MAO coatings can extend the incubation period of aluminum alloy, and thus enhance the cavitation erosion resistance as compared to the untreated aluminum alloy samples. After duration of 63 h cavitation test, a lot of erosion pits and the particles in various shapes can be observed on the surfaces of the aluminum alloy samples, while only a few erosion pits are observed on the MAO coatings. Moreover, the mean depths of erosion on the MAO coatings are lower in the first 30 h and are independent on erosion time. The results show that the cavitation erosion of MAO coating is governed by water mechanical impaction, resulting from the effects of brittle fracture of the MAO coating.

110

Peroxide induced tin oxide coating of graphene oxide at room temperature and its application for lithium ion batteries  

International Nuclear Information System (INIS)

We describe a new, simple and low-temperature method for ultra-thin coating of graphene oxide (GO) by peroxostannate, tin oxide or a mixture of tin and tin oxide crystallites by different treatments. The technique is environmentally friendly and does not require complicated infrastructure, an autoclave or a microwave. The supported peroxostannate phase is partially converted after drying to crystalline tin oxide with average, 2.5 nm cassiterite crystals. Mild heat treatment yielded full coverage of the reduced graphene oxide by crystalline tin oxide. Extensive heat treatment in vacuum at >500? °C yielded a mixture of elemental tin and cassiterite tin oxide nanoparticles supported on reduced graphene oxide (rGO). The usefulness of the new approach was demonstrated by the preparation of two types of lithium ion anodes: tin oxide–rGO and a mixture of tin oxide and tin coated rGO composites (SnO2–Sn–rGO). The electrodes exhibited stable charge/discharge cyclability and high charging capacity due to the intimate contact between the conductive graphene and the very small tin oxide crystallites. The charging/discharging capacity of the anodes exceeded the theoretical capacity predicted based on tin lithiation. The tin oxide coated rGO exhibited higher charging capacity but somewhat lower stability upon extended charge/discharge cycling compared to SnO2–Sn–rGO. (paper)

111

Characterization of microarc oxidation coatings formed on AM60B magnesium alloy in silicate and phosphate electrolytes  

Energy Technology Data Exchange (ETDEWEB)

Microarc oxidation coatings on AM60B magnesium alloy were prepared in silicate and phosphate electrolytes. Structure, composition, mechanical property, tribological, and corrosion resistant characteristics of the coatings was studied by scanning electron microscope (SEM), X-ray diffraction (XRD) and microhardness analyses, and by ball-on-disc friction and potentiodynamic corrosion testing. It is found that the coating produced from the silicate electrolyte is compact and uniform and is mainly composed of MgO and forsterite Mg{sub 2}SiO{sub 4} phases, while the one formed in phosphate electrolyte is relatively porous and is mainly composed of MgO phase. The thick coating produced from a silicate electrolyte possesses a high hardness and provides a low wear rate (3.55 x 10{sup -5} mm{sup 3}/Nm) but a high friction coefficient against Si{sub 3}N{sub 4} ball. A relatively low hardness and friction coefficient while a high wear rate (8.65 x 10{sup -5} mm{sup 3}/Nm) is recorded during the testing of the thick coating produced from a phosphate electrolyte. Both of these types of coatings provide effective protection for the corrosion resistance compared with the uncoated magnesium alloy. The coating prepared from the silicate electrolyte demonstrates better corrosion behavior due to the compacter microstructure.

Liang Jun [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China) and Graduate School of Chinese Academy of Sciences, Beijing 100039 (China)]. E-mail: liangjun9@yahoo.com.cn; Hu Litian [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Hao Jingcheng [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)]. E-mail: jhao@sdu.edu.cn

2007-03-15

112

Characterization of microarc oxidation coatings formed on AM60B magnesium alloy in silicate and phosphate electrolytes  

Science.gov (United States)

Microarc oxidation coatings on AM60B magnesium alloy were prepared in silicate and phosphate electrolytes. Structure, composition, mechanical property, tribological, and corrosion resistant characteristics of the coatings was studied by scanning electron microscope (SEM), X-ray diffraction (XRD) and microhardness analyses, and by ball-on-disc friction and potentiodynamic corrosion testing. It is found that the coating produced from the silicate electrolyte is compact and uniform and is mainly composed of MgO and forsterite Mg 2SiO 4 phases, while the one formed in phosphate electrolyte is relatively porous and is mainly composed of MgO phase. The thick coating produced from a silicate electrolyte possesses a high hardness and provides a low wear rate (3.55 × 10 -5 mm 3/Nm) but a high friction coefficient against Si 3N 4 ball. A relatively low hardness and friction coefficient while a high wear rate (8.65 × 10 -5 mm 3/Nm) is recorded during the testing of the thick coating produced from a phosphate electrolyte. Both of these types of coatings provide effective protection for the corrosion resistance compared with the uncoated magnesium alloy. The coating prepared from the silicate electrolyte demonstrates better corrosion behavior due to the compacter microstructure.

Liang, Jun; Hu, Litian; Hao, Jingcheng

2007-03-01

113

Characterization of microarc oxidation coatings formed on AM60B magnesium alloy in silicate and phosphate electrolytes  

International Nuclear Information System (INIS)

Microarc oxidation coatings on AM60B magnesium alloy were prepared in silicate and phosphate electrolytes. Structure, composition, mechanical property, tribological, and corrosion resistant characteristics of the coatings was studied by scanning electron microscope (SEM), X-ray diffraction (XRD) and microhardness analyses, and by ball-on-disc friction and potentiodynamic corrosion testing. It is found that the coating produced from the silicate electrolyte is compact and uniform and is mainly composed of MgO and forsterite Mg2SiO4 phases, while the one formed in phosphate electrolyte is relatively porous and is mainly composed of MgO phase. The thick coating produced from a silicate electrolyte possesses a high hardness and provides a low wear rate (3.55 x 10-5 mm3/Nm) but a high friction coefficient against Si3N4 ball. A relatively low hardness and friction coefficient while a high wear rate (8.65 x 10-5 mm3/Nm) is recorded during the testing of the thick coating produced from a phosphate electrolyte. Both of these types of coatings provide effective protection for the corrosion resistance compared with the uncoated magnesium alloy. The coating prepared from the silicate electrolyte demonstrates better corrosion behavior due to the compacter microstructure

114

Selection of a Commercial Anode Oxide Coating for Electro-oxidation of Cyanide  

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Full Text Available This paper presents a study of the performance of two commercial dimensionally stable anode (DSA® oxide coatings in the electrochemical process for cyanide oxidation. The coatings studied were 70TiO2/30RuO2 and 55Ta2O5/45IrO2, on Ti substrate. The efficiency of both materials in the electro-oxidation of free cyanide was compared using linear voltammetry and electrolysis at constant potential. The 70TiO2/30RuO2 electrode shows a better performance in the electro-oxidation of free cyanide.

Lanza Marcos Roberto V.

2002-01-01

115

Preparation and properties of poly(vinylidene fluoride nanocomposites blended with graphene oxide coated silica hybrids  

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Full Text Available Graphene oxide coated silica hybirds (SiO2-GO were fabricated through electrostatic assembly in this work, then blended with poly(vinylidene fluoride (PVDF by solution mixing to make PVDF nanocomposites. The interfacial interaction was investigated by scanning electron microscopy (SEM, polarized optical microscopy (POM and Fourier transform infrared spectroscopy (FTIR. The results showed that the interfacial interaction was enhanced by adding of SiO2-GO and strong hydrogen bonds were observed. The as-made nanocomposites were investigated using standard tensile test and dynamic mechanical analysis (DMA measurements, mechanical properties of PVDF with SiO2-GO hybrids showed limited improvement.

Q. Fu

2012-04-01

116

Laccase Immobilized on a PAN/Adsorbents Composite Nanofibrous Membrane for Catechol Treatment by a Biocatalysis/Adsorption Process  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The treatment of catechol via biocatalysis and adsorption with a commercial laccase immobilized on polyacrylonitrile/montmorillonite/graphene oxide (PAN/MMT/GO) composite nanofibers was evaluated with a homemade nanofibrous membrane reactor. The properties in this process of the immobilized laccase on PAN, PAN/MMT as well as PAN/MMT/GO with different weight ratios of MMT and GO were investigated. These membranes were successfully applied for removal of catechol from an aqueous solution. Scann...

Qingqing Wang; Jing Cui; Guohui Li; Jinning Zhang; Dawei Li; Fenglin Huang; Qufu Wei

2014-01-01

117

The composition of mixed surfactants and cationic polymer/surfactant mixtures adsorbed at the air-water interface  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The use of specular neutron reflection and small-angle neutron scattering (SANS) to determine the composition of mixed surfactants and polymer/surfactant mixtures, absorbed at the air-water interface, in micelles and polymer or micellar complexes, is described. For the characterisation of adsorption at the air-water interface by neutron reflectivity, the emphasis is predominantly on the concentration regime where the surface is in equilibrium with a bulk aggregated phase; that is, for concent...

Penfold, J.; Staples, E.; Tucker, I.; Creeth, A.; Hines, J.; Thompson, L.; Cummins, P.; Thomas, Rk; Warren, N.

1997-01-01

118

Composition of mixed surfactant-polymer layers adsorbed at the air/water interface as determined by specular neutron reflection  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Specular neutron reflection has been used to evaluate the adsorption of the anionic surfactant, sodium dodecyl sulfate, SDS, and of the mixed anionic-non-ionic surfactants of SDS and hexaethylene monododecyl ether, C 12E 6, in the presence of cationic polymers (dimethyldialylammonium chloride-acrylamide copolymers) at the air/water interface. The surface composition of the mixed surfactants SDS-C 12E ...

Creeth, A.; Staples, E.; Thompson, L.; Tucker, I.; Penfold, J.

1996-01-01

119

Influence of preparation conditions of adsorbents of Al(OH)3-ZrSiO4 composition on porous structure  

International Nuclear Information System (INIS)

Effect of component ratio, sequence of their precipitation, calcination temperature on adsorption-structure characteristics and on phase composition of Al(OH)3-ZrSiO4 system is studied. Specimens with 30 mas. % Al(OH)3 and 70 mas. % ZrSiO4 content are shown to have maximal sorption capacity and specific surface regardless of component precipitation sequence. It is possible to regulate within certain limits both sorption properties of the obtained specimens and their thermal stability by changing ratio of components in the studied system

120

High capacity magnetic mesoporous carbon-cobalt composite adsorbents for removal of methylene green from aqueous solutions.  

Science.gov (United States)

Mesoporous carbons containing cobalt nanoparticles are synthesized by tri-or quad-constituent self assembly of Pluronic F127, phenol-formaldehyde oligomer (resol), cobalt acetylacetonate (acac), and optionally tetraethyl orthosilicate (TEOS, optional). Upon pyrolysis in N(2) atmosphere, the resol provides sufficient carbon yield to maintain the ordered structure, while decomposition of the Co(acac) yields cobalt nanoparticles. To provide increased surface area, the dispersed silicate from condensation of TEOS can be etched after carbonization to yield micropores, Without silica templated micropores, the surface area decreases as the cobalt content increases, but there is a concurrent increase in the volume-average pore diameter (BHJ) and a dramatic increase in the adsorption capacity of methylene green with the equilibrium adsorption capacity from 2 to 90 mg/g with increasing Co content. Moreover, the surface area and pore size of mesoporous composites can be dramatically increased by addition of TEOS and subsequent etching. These composites exhibit extremely high adsorption capacity up to 1151 mg/g, which also increases with increases in the Co content. Additionally, the inclusion of cobalt nanoparticles provides magnetic separation from aqueous suspension. The in situ synthesis of the Co nanoparticles yields to a carbon shell that can partially protect the Co from leaching in acidic media; after 96 h in 2 M HCl, the powders remain magnetic. PMID:22975394

Dai, Mingzhi; Vogt, Bryan D

2012-12-01

 
 
 
 
121

Photoluminescence blue shift of indium phosphide nanowire networks with aluminum oxide coating  

Energy Technology Data Exchange (ETDEWEB)

This paper describes our finding that optical properties of semiconductor nanowires were modified by depositing a thin layer of metal oxide. Indium phosphide nanowires were grown by metal organic chemical vapor deposition on silicon substrates with gold catalyst resulting in three-dimensional nanowire networks, and optical properties were obtained from the collective nanowire networks. The networks were coated with an aluminum oxide thin film deposited by plasma-enhanced atomic layer deposition. We studied the dependence of the peak wavelength of photoluminescence spectra on the thickness of the oxide coatings. A continuous blue shift in photoluminescence spectra was observed when the thickness of the oxide coating was increased. The observed blue shift is attributed to the Burstein-Moss effect due to increased carrier concentration in the nanowire cores caused by repulsion from intrinsic negative fixed charges located at the inner oxide surface. Samples were further characterized by scanning electron microscopy, Raman spectroscopy, transmission electron microscopy, and selective area diffractometry to better understand the physical mechanisms for the blue shift. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Fryauf, David M.; Zhang, Junce; Norris, Kate J.; Diaz Leon, Juan J.; Oye, Michael M.; Kobayashi, Nobuhiko P. [Nanostructured Energy Conversion Technology and Research (NECTAR), Advanced Studies Laboratories, University of California, Santa Cruz, CA (United States); Baskin School of Engineering, University of California Santa Cruz, Santa Cruz, CA (United States); NASA Ames Research Center, Moffett Field, CA (United States); Wei, Min [Baskin School of Engineering, University of California Santa Cruz, Santa Cruz, CA (United States); School of Micro-Electronics and Solid-Electronics, University of Electronic Science and Technology of China, Chengdu (China)

2014-07-15

122

Photoluminescence blue shift of indium phosphide nanowire networks with aluminum oxide coating  

International Nuclear Information System (INIS)

This paper describes our finding that optical properties of semiconductor nanowires were modified by depositing a thin layer of metal oxide. Indium phosphide nanowires were grown by metal organic chemical vapor deposition on silicon substrates with gold catalyst resulting in three-dimensional nanowire networks, and optical properties were obtained from the collective nanowire networks. The networks were coated with an aluminum oxide thin film deposited by plasma-enhanced atomic layer deposition. We studied the dependence of the peak wavelength of photoluminescence spectra on the thickness of the oxide coatings. A continuous blue shift in photoluminescence spectra was observed when the thickness of the oxide coating was increased. The observed blue shift is attributed to the Burstein-Moss effect due to increased carrier concentration in the nanowire cores caused by repulsion from intrinsic negative fixed charges located at the inner oxide surface. Samples were further characterized by scanning electron microscopy, Raman spectroscopy, transmission electron microscopy, and selective area diffractometry to better understand the physical mechanisms for the blue shift. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

123

Adsorption of Th{sup 4+}, U{sup 6+}, Cd{sup 2+}, and Ni{sup 2+} from aqueous solution by a novel modified polyacrylonitrile composite nanofiber adsorbent prepared by electrospinning  

Energy Technology Data Exchange (ETDEWEB)

In this study, SiO{sub 2} nanoparticles were modified by 3-aminopropyltriethoxysilane (APTES) and then applied to prepare a novel polyacrylonitrile (PAN) composite nanofiber adsorbent by the electrospinning method. In addition, the adsorbent was characterized by SEM, BET, and FTIR analyses. Then the effects of pH, SiO{sub 2} and APTES content, adsorbent dosage, contact time and temperature were investigated. Moreover, adsorption experiments were carried out with initial concentrations in the range of 30–500 mg L{sup ?1} and the adsorbent affinity for metal ions was in order of Th{sup 4+} > U{sup 6+} > Cd{sup 2+} > Ni{sup 2+}. Furthermore, it was observed that the optimum pH for adsorption was different for each metal. Some isotherm and kinetic models were applied to analyze the experimental data, among which the Langmuir and pseudo-second order models were better than the others. The regeneration study showed that the adsorbent could be used for industrial processes repeatedly without any significant reduction in its adsorption capacity. Based on the Langmuir model, the maximum adsorption capacity of Th{sup 4+}, U{sup 6+}, Cd{sup 2+}, and Ni{sup 2+} at 45 °C was 249.4, 193.1, 69.5 and 138.7 mg g{sup ?1}, respectively. Besides, the calculated thermodynamic parameters showed an endothermic as well as chemical nature through the adsorption process.

Dastbaz, Abolfazl [Department of Chemical engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Keshtkar, Ali Reza, E-mail: akeshtkar@aeoi.org.ir [Nuclear Fuel Cycle Research School, Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of)

2014-02-28

124

Synthesis of linear low-density polyethylene-g-poly (acrylic acid)-co-starch/organo-montmorillonite hydrogel composite as an adsorbent for removal of Pb(??) from aqueous solutions.  

Science.gov (United States)

The purpose of this work is to remove Pb(II) from the aqueous solution using a type of hydrogel composite. A hydrogel composite consisting of waste linear low density polyethylene, acrylic acid, starch, and organo-montmorillonite was prepared through emulsion polymerization method. Fourier transform infrared spectroscopy (FTIR), Solid carbon nuclear magnetic resonance spectroscopy (CNMR)), silicon(-29) nuclear magnetic resonance spectroscopy (Si NMR)), and X-ray diffraction spectroscope ((XRD) were applied to characterize the hydrogel composite. The hydrogel composite was then employed as an adsorbent for the removal of Pb(II) from the aqueous solution. The Pb(II)-loaded hydrogel composite was characterized using Fourier transform infrared spectroscopy (FTIR)), scanning electron microscopy (SEM)), and X-ray photoelectron spectroscopy ((XPS)). From XPS results, it was found that the carboxyl and hydroxyl groups of the hydrogel composite participated in the removal of Pb(II). Kinetic studies indicated that the adsorption of Pb(II) followed the pseudo-second-order equation. It was also found that the Langmuir model described the adsorption isotherm better than the Freundlich isotherm. The maximum removal capacity of the hydrogel composite for Pb(II) ions was 430mg/g. Thus, the waste linear low-density polyethylene-g-poly (acrylic acid)-co-starch/organo-montmorillonite hydrogel composite could be a promising Pb(II) adsorbent. PMID:25597658

Irani, Maryam; Ismail, Hanafi; Ahmad, Zulkifli; Fan, Maohong

2015-01-01

125

Synthesis of the magnetic biochar composites for use as an adsorbent for the removal of pentachlorophenol from the effluent.  

Science.gov (United States)

The zero-valent iron magnetic biochar composites (ZVI-MBC) were synthesized from the paper mill sludge biochar and used for the treatment of the synthetic and real effluent containing pentachlorophenol (PCP). During the synthesis of ZVI-MBC, NaBH4 was used as the reducing agent to reduce Fe(II) to Fe(0) and cetyltrimethylammonium bromide was added as surfactant. The effect of the molar ratio of FeSO4 to NaBH4, dose of the surfactant and the ZVI to biochar ratio on the PCP removal efficiency was investigated. It was found that the ZVI-MBC combines the advantages of biochar and ZVI particles for the simultaneous adsorption and dechlorination of PCP in the effluent and the complete removal of PCP was obtained. The ageing tests showed that biochar prevents the formation of oxide film on the ZVI particles and leaching tests confirmed the stability of ZVI on biochar matrix as very low iron leaching was noticed. PMID:25089893

Devi, Parmila; Saroha, Anil K

2014-10-01

126

Influence of sodium silicate concentration on structural and tribological properties of microarc oxidation coatings on 2017A aluminum alloy substrate  

International Nuclear Information System (INIS)

In this paper, thick and hard oxide coatings resistant to wear were produced on 2017A-T6 Al alloy by the microarc oxidation (MAO) technique in an alkali electrolyte consisting of different sodium silicate concentrations (0-8 g/l). The coatings were characterized by means of optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and surface profilometry. Microhardness, scratch adhesion and pin-on-disk sliding wear tests were also performed to evaluate the tribological properties of the coatings. The influence of sodium silicate concentration on the structural and tribological properties of the MAO coatings was discussed. Results reveal that increasing sodium silicate concentration from 0 to 8 g/l in the electrolyte caused an increase in the electrolyte conductivity (from 7.71 to 18.1 mS/cm) and a decrease in positive final voltage (from 627 to 590 V) in the MAO process. In response to the increase in sodium silicate concentration, the thickness, surface roughness (Ra) and critical load (Lc) corresponding to adhesive failure of the coatings were increased simultaneously from 74 to 144 ?m, and 4.4 to 6.58 ?m, and 127.76 to 198.54 N, respectively. At the same time, the phase structure and composition of the coatings also varied by the participation of silicate ions in the reactions and their incorporation into the coating structure. Moreover, it was observed that the coating formed in the low sodium silicate concentration ( the low sodium silicate concentration (4 g/l) had higher surface hardness (2020 HV) and improved wear resistance than the one (1800 HV) formed in the high sodium silicate concentration (8 g/l). The coatings produced in three different electrolytic solutions provided an excellent wear resistance and a load carrying capacity compared to the uncoated aluminum alloy.

127

Influence of sodium silicate concentration on structural and tribological properties of microarc oxidation coatings on 2017A aluminum alloy substrate  

Energy Technology Data Exchange (ETDEWEB)

In this paper, thick and hard oxide coatings resistant to wear were produced on 2017A-T6 Al alloy by the microarc oxidation (MAO) technique in an alkali electrolyte consisting of different sodium silicate concentrations (0-8 g/l). The coatings were characterized by means of optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and surface profilometry. Microhardness, scratch adhesion and pin-on-disk sliding wear tests were also performed to evaluate the tribological properties of the coatings. The influence of sodium silicate concentration on the structural and tribological properties of the MAO coatings was discussed. Results reveal that increasing sodium silicate concentration from 0 to 8 g/l in the electrolyte caused an increase in the electrolyte conductivity (from 7.71 to 18.1 mS/cm) and a decrease in positive final voltage (from 627 to 590 V) in the MAO process. In response to the increase in sodium silicate concentration, the thickness, surface roughness (R{sub a}) and critical load (L{sub c}) corresponding to adhesive failure of the coatings were increased simultaneously from 74 to 144 {mu}m, and 4.4 to 6.58 {mu}m, and 127.76 to 198.54 N, respectively. At the same time, the phase structure and composition of the coatings also varied by the participation of silicate ions in the reactions and their incorporation into the coating structure. Moreover, it was observed that the coating formed in the low sodium silicate concentration (4 g/l) had higher surface hardness (2020 HV) and improved wear resistance than the one (1800 HV) formed in the high sodium silicate concentration (8 g/l). The coatings produced in three different electrolytic solutions provided an excellent wear resistance and a load carrying capacity compared to the uncoated aluminum alloy.

Polat, Aytekin, E-mail: apolat@nigde.edu.t [Department of Mechanical Engineering, Nigde University, Nigde 51100 (Turkey); Makaraci, Murat [Department of Mechanical Engineering, Kocaeli University, Kocaeli (Turkey); Usta, Metin [Department of Materials Science and Engineering, Gebze Institute of Technology, Kocaeli (Turkey)

2010-08-20

128

A spectroscopic and microstructural study of oxide coatings produced on a Ti–6Al–4V alloy by plasma electrolytic oxidation  

International Nuclear Information System (INIS)

Highlights: ? PEO (plasma electrolytic oxidation) for production of oxide coatings on a Ti–6Al–4V alloy. ? Two different current modes namely pulsed unipolar and bipolar was used. ? Optical emission spectroscopy (OES) was used to characterize the PEO plasma. ? This is the first attempt to characterize spectroscopically the PEO plasma of Ti and its alloys. ? The discharge behavior effect on the formation and structure of the coating was determined. - Abstract: In this study, we have used PEO (plasma electrolytic oxidation) for the production of oxide coatings on a Ti–6Al–4V alloy at two different current modes, namely pulsed unipolar and bipolar. Optical emission spectroscopy (OES) in the visible and near UV band (280–800 nm) was used to characterize the PEO plasma. The emission spectra were recorded and the plasma temperature profile versus processing time was constructed using a line intensity ratios method. The aim of this work was to study the effect of the process parameters, including current mode and pulse duration time, on the plasma characteristics, surface morphology and microstructure and corrosion resistance of oxides grown on Ti–6Al–4V by PEO process. Scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDS) and X-ray diffraction (XRD) were used to study the coating microstructure, morphology and phase composition. The corrosion resistance of the coated and uncoated samples was examined by potentiodynamic polarintiodynamic polarization in a 3.5% NaCl solution. It was found that the plasma temperature profiles are significantly influenced by changing the current mode from unipolar to bipolar. The strongest discharges that are initiated at the interface between the substrate and the coating can be reduced or eliminated by using a bipolar current mode. This produces a thinner, denser and more corrosion-resistant coating.

129

Indium tin oxide coatings properties as a function of the deposition atmosphere  

International Nuclear Information System (INIS)

Indium tin oxide coatings were deposited by magnetron sputtering physical vapour deposition under different atmospheres. Microstructural, electrical, and optical properties were measured, finding a correlation among properties and process parameters. Texture analyses carried out by X-ray diffraction showed that films microstructure depended by the oxygen content in the deposition vessel: high values of the oxygen content (e.g., 5%) caused the film to grow along the orientation; under pure Ar, the grains grew along the orientation. Intermediate values of the oxygen content caused the growth of two families of grains, respectively oriented along the and the directions. - Highlights: ? Correlation between deposition atmosphere and indium tin oxide films properties ? Resistivity and transmittance depended by the O2 content in the deposition vessel. ? At high oxygen content, the films grew along the direction. ? At low oxygen content, the films grew along the direction. ? Intermediate oxygen contents allowed the growth of both the orientations.

130

Titanium-nitride-oxide-coated Titan-2 bioactive coronary stent: a new horizon for coronary intervention.  

Science.gov (United States)

The introduction of drug-eluting stents has revolutionized the field of interventional cardiology, since it has reduced the incidence of restenosis by 50-70%. However, recent worrisome data from registries and meta-analyses emphasized higher rates of late and very late stent thrombosis associated with drug-eluting stents. The recently introduced titanium-nitride-oxide-coated stent (Titan-2) has demonstrated an excellent biocompatibility, as reflected by lower rates of platelet aggregation and fibrin deposition, and better endothelialization. Preclinical and clinical trials and registries involving both real-life unselected populations and populations with the most challenging patient and lesion characteristics have shown a low rate of major adverse cardiac events in the long-term, with a restenosis rate comparable with that of drug-eluting stents, with the virtual absence of stent thrombosis. PMID:20822383

Karjalainen, Pasi P; Ylitalo, Antti; Airaksinen, Juhani K E; Nammas, Wail

2010-09-01

131

Evaluation of the mechanical properties of microarc oxidation coatings and 2024 aluminium alloy substrate  

CERN Document Server

A determination of the phase constituents of ceramic coatings produced on Al-Cu-Mg alloy by microarc discharge in alkaline solution was performed using x-ray diffraction. The profiles of the hardness, H, and elastic modulus, E, across the ceramic coating were determined by means of nanoindentation. In addition, a study of the influence of microarc oxidation coatings on the tensile properties of the aluminium alloy was also carried out. The results show that the H-and E-profiles are similar, and both of them exhibit a maximum value at the same depth of coating. The distribution of the alpha-Al sub 2 O sub 3 phase content determines the H- and E-profiles of the coatings. The tensile properties of 2024 aluminium alloy show less change after the alloy has undergone microarc discharge surface treatment.

Xue Wen Bin; Deng Zhi Wei; Chen Ru Yi; Li Yong Liang; Zhang Ton Ghe

2002-01-01

132

On the application of acoustic emission analysis to evaluate the integrity of protective oxide coatings  

International Nuclear Information System (INIS)

Protective coatings extend the range of applications for materials. Surface properties can be selectively adapted for each problem. Thus bare high-temperature alloys for heat exchanging units e.g. in high-temperature systems for producing substitute natural gas do not have sufficient protection against undesirable tritium permeation from the helium primary gas into the substitute natural gas generated. A chromium oxid coating, on the other hand, of only a few ?m in thickness ensures a barrier effect combines with an inhibitive factor H = 1000. Good adhesion is required for a successful application, in the same way as good temperature cycling resistance under start-up and shut-down conditions is of decisive significance for every type of coating

133

Electron transport behavior of individual zinc oxide coated single-walled carbon nanotubes  

International Nuclear Information System (INIS)

Uniform zinc oxide coated single-walled nanotubes (SWNTs) were fabricated by ultrasonic irradiation with acid-treated SWNTs, zinc acetate, and triethanolamine at low temperature in aqueous phase processing. The ZnO coating process did not decrease the dark current of the SWNTs, but a real decrease in the steady state negative photocurrent was observed after ZnO coating, suggesting a clear photosensitization effect. Transport measurements reveal that the negative photocurrent in s (semiconducting)-SWNTs-ZnO could be described by electron-hole compensation behavior attributed to the ZnO layer under ultraviolet excitation. This simple coating method for one-dimensional material can open up new possibilities for multifunctional nanodevices.

134

BACTERIOPHAGE PRD1 AND SILICA COLLOID TRANSPORT AND RECOVERY IN AN IRON OXIDE-COATED SAND AQUIFER. (R826179)  

Science.gov (United States)

Bacteriophage PRD1 and silica colloids were co-injected into sewage-contaminated and uncontaminated zones of an iron oxide-coated sand aquifer on Cape Cod, MA, and their transport was monitored over distances up to 6 m in three arrays. After deposition, the attache...

135

Surface chemistry of metal oxide coated lithium manganese nickel oxide thin film cathodes studied by XPS  

International Nuclear Information System (INIS)

Highlights: ? LiMn1.5Ni0.5O4 spinel thin films were prepared by RF magnetron sputtering. ? The effect of thin metal oxide coatings on cycling and surface chemistry has been studied upon cycling by X-ray photoelectron spectroscopy. ? ZrO2 limits the available storage capacity. ZnO dissolves at potentials larger than 4.7 V vs. Li/Li+. Al2O3 is stable upon long cycling. ? Ethers, esters, LiF and LixPOyFz are the main constituents of the CEI surface layer. -- Abstract: The effect of coating the high voltage spinel cathode LiMn1.5Ni0.5O4 with three metal oxide thin layers is discussed. Instead of the typical powder electrodes with poorly defined surface coatings, thin film electrodes were prepared with well-defined oxide coating thicknesses to investigate the influence of coating on surface reactivity via X-ray photoelectron spectroscopy (XPS). ZnO is found to decompose during the first charge whereas Al2O3 and ZrO2 are stable for more than 100 cycles. ZrO2, however, importantly limits the available Li storage capacity of the electrochemical reaction due to poorer kinetics. Al2O3 offers the best results in term of capacity retention. Upon cycling, the evidence of a signal at 75.4 eV in the Al2p binding energy spectrum indicates the partial fluorination of Al2O3 into, perhaps, Al2O2F2. Moreover, the continuous formation of ethers, esters and LixPOyFz compounds on the surface of the electrodes is found for all coating materials

136

Superhydrophilicity and antibacterial property of a Cu-dotted oxide coating surface  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Aluminum-made settings are widely used in healthcare, schools, public facilities and transit systems. Frequently-touched surfaces of those settings are likely to harbour bacteria and be a potential source of infection. One method to utilize the effectiveness of copper (Cu in eliminating pathogens for these surfaces would be to coat the aluminum (Al items with a Cu coating. However, such a combination of Cu and Al metals is susceptible to galvanic corrosion because of their different electrochemical potentials. Methods In this work, a new approach was proposed in which electrolytic plasma oxidation (EPO of Al was used to form an oxide surface layer followed by electroplating of Cu metal on the top of the oxide layer. The oxide was designed to function as a corrosion protective and biocompatible layer, and the Cu in the form of dots was utilized as an antibacterial material. The antibacterial property enhanced by superhydrophilicity of the Cu-dotted oxide coating was evaluated. Results A superhydrophilic surface was successfully prepared using electrolytic plasma oxidation of aluminum (Al followed by electroplating of copper (Cu in a Cu-dotted form. Both Cu plate and Cu-dotted oxide surfaces had excellent antimicrobial activities against E. coli ATCC 25922, methicillin-resistant Staphylococcus aureus (MRSA ATCC 43300 and vancomycin-resistant Enterococcus faecium (VRE ATCC 51299. However, its Cu-dotted surface morphology allowed the Cu-dotted oxide surface to be more antibacterial than the smooth Cu plate surface. The enhanced antibacterial property was attributed to the superhydrophilic behaviour of the Cu-dotted oxide surface that allowed the bacteria to have a more effective killing contact with Cu due to spreading of the bacterial suspension media. Conclusion The superhydrophilic Cu-dotted oxide coating surface provided an effective method of controlling bacterial growth and survival on contact surfaces and thus reduces the risk of infection and spread of bacteria-related diseases particularly in moist or wet environments.

Nie Yining

2010-09-01

137

Reconstruction mechanisms of tantalum oxide coatings with low concentrations of silver for high temperature tribological applications.  

Science.gov (United States)

Silver tantalate (AgTaO3) coatings have been found to exhibit outstanding tribological properties at elevated temperatures. To understand the mechanisms involved in the tribological behavior of the Ag-Ta-O system, tantalum oxide coatings with a small content of silver were produced to investigate the metastable nature of this self-lubricating material. The coatings were produced by unbalanced magnetron sputtering, ball-on-disk wear tested at 750?°C, and subsequently characterized by X-ray diffraction, Scanning Auger Nanoprobe, cross-sectional Scanning Electron Microscopy, and Transmission Electron Microscopy. Complementary molecular dynamic simulations were carried out to investigate changes in the chemical and structural properties at the interface due to sliding for films with varying silver content. Both the experimental characterization and the theoretical modeling showed that silver content affects friction and wear, through the role of silver in film reconstruction during sliding. The results suggest that the relative amount of silver may be used to tune film performance for a given application. PMID:25425745

Stone, D S; Gao, H; Chantharangsi, C; Paksunchai, C; Bischof, M; Martini, A; Aouadi, S M

2014-11-10

138

Fabrication of density-controlled graphene oxide-coated mesoporous silica spheres and their electrorheological activity.  

Science.gov (United States)

A series of density-controlled graphene oxide-coated mesoporous silica spheres (GO/SiO2) are successfully synthesized to investigate the influence of the particle density on electrorheological (ER) activity. The particle density of mesoporous silica spheres is controlled by creating different sized pores via surfactant template and swelling agent incorporation method. Additionally, ball-milled graphene oxide is successfully coated onto the surface of various silica spheres (SiO2) through amine-modification to enhance ER efficiency. In this study, we investigate that mesoporous silica spheres-based ER fluid (GO/epSiO2) with lowest particle density exhibit most increased ER performance, which is 3-fold higher than that of similar sized neat silica spheres-based ER fluid (GO/nSiO2) without pore. In addition, the relationship between particle density, anti-sedimentation property, and ER performance is examined by applying Stokes' law and practical sedimentation observation. Furthermore, dielectric loss model is used to clarify the influence of dielectric property on ER activity. This newly designed ER study offers insight into the influence of the particle density on the performance of ER fluids. PMID:25454420

Yoon, Chang-Min; Lee, Seungae; Hong, Seung Hee; Jang, Jyongsik

2015-01-15

139

Annealing effects on microstructure and mechanical properties of chromium oxide coatings  

Energy Technology Data Exchange (ETDEWEB)

Reactive radio frequency magnetron sputter-deposited chromium oxide coatings were annealed at different temperatures and times. The influence of annealing temperature on the microstructure, surface morphology and mechanical properties was examined by X-ray diffraction, nanoindentation, pin-on-disc wear and scratch tests, respectively. X-ray results show that the chromium oxide sputtered at room temperature in low oxygen flux is primarily amorphous. Annealing below 400 deg. C did not cause much change, while annealing at higher temperature of 500 deg. C caused a significant change in microstructure and mechanical properties. Hardness increased from 12.3 GPa to 26 GPa, and the wearability improved with higher annealing temperature due to the formation of crystalline Cr{sub 2}O{sub 3} phase, which occurs at 470 deg. C. Annealing time had little effect on mechanical properties and microstructure, although coating surface roughness increased with a longer annealing time. Coating adhesion was improved by annealing, due to residual stress relief and possible interfacial interdiffusion.

Pang Xiaolu [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Department of Mechanical Engineering, University of South Florida, Tampa, FL 33620 (United States); Gao Kewei [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China)], E-mail: kwgao@yahoo.com; Luo Fei; Yang Huisheng; Qiao Lijie; Wang Yanbin [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Volinsky, Alex A. [Department of Mechanical Engineering, University of South Florida, Tampa, FL 33620 (United States)

2008-06-02

140

Antibacterial properties and cytocompatibility of tantalum oxide coatings with different silver content  

Energy Technology Data Exchange (ETDEWEB)

Tantalum (Ta) oxides and their coatings have been proved to increase their applications in the biomedical fields by improving osseointegration and wear resistance. In this study, Ta oxide coatings containing different proportions of Ag are deposited on SS304 materials. A twin-gun magnetron sputtering system is used to deposit the tantalum oxide-Ag coating. In this study, Staphylococcus aureus, which exhibits physiological commensalism on the human skin, nares, and mucosal and oral areas, is chosen as the model for in vitro antibacterial analyses via a fluorescence staining method using Syto9. The cytocompatibility and adhesive morphology of human skin fibroblast cells (CCD-966SK) on the coatings are also determined by using the microculture tetrazolium assay. This study shows that Ta{sub 2}O{sub 5} and Ta{sub 2}O{sub 5}-Ag coatings with 12.5 at. % of Ag exhibit improved antibacterial effects against S. aureus and have good skin fibroblast cell cellular biocompatibility.

Huang, Heng-Li [School of Dentistry, China Medical University, Taichung 404, Taiwan (China); Chang, Yin-Yu, E-mail: yinyu@mail2000.com.tw; Chen, Hung-Jui; Chou, Yu-Kai [Department of Mechanical and Computer-Aided Engineering, National Formosa University, Yunlin 632, Taiwan (China); Lai, Chih-Ho [School of Medicine, China Medical University, Taichung 404, Taiwan (China); Chen, Michael Y. C. [Division of Oral and Maxillofacial Surgery, China Medical University Hospital, Taichung 404, Taiwan (China)

2014-03-15

 
 
 
 
141

Deuterium permeation through erbium oxide coatings on RAFM steels by a dip-coating technique  

Energy Technology Data Exchange (ETDEWEB)

A tritium permeation barrier is a promising solution for the problems of tritium loss and radiological safety in fusion blanket systems. In recent years, erbium oxide coatings have shown remarkable permeation reduction factors. One of the remaining issues for the coatings is the establishment of plant-scale fabrication. In this study, erbium oxide thin films have been fabricated by a dip-coating technique, which has the potential to coat a complex-shaped substrate, and deuterium permeation behavior in the coatings has been examined. Crack-free coatings were formed on a reduced activation ferritic/martensitic steel F82H substrate by use of a withdrawal speed of 1.0–1.4 mm s{sup ?1} and a heat-treatment process in hydrogen with moisture. In deuterium permeation experiments, a 0.2-?m-thick coating on both sides of the substrate showed a reduction factor of 600–700 in comparison with a F82H substrate below 873 K; however, the coating degraded at above 923 K because of crack formation. A double-coated sample indicated a reduction factor of up to 2000 and did not degrade at up to 923 K. The driving pressure dependence of the deuterium permeation flux indicated that the permeation tended to be limited by surface reactions at low temperatures. Optimization of the number of layers has the possibility to reduce degradation at high temperatures while maintaining high permeation reduction factors.

Chikada, Takumi, E-mail: chikada@nuclear.jp [Institute of Engineering Innovation, School of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan); Naitoh, Shunya [Department of Systems Innovation, Faculty of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Suzuki, Akihiro [Nuclear Professional School, School of Engineering, The University of Tokyo, 2-22 Shirakata-shirane, Tokai, Naka, Ibaraki 319-1188 (Japan); Terai, Takayuki [Institute of Engineering Innovation, School of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan); Tanaka, Teruya; Muroga, Takeo [Fusion Systems Research Division, Department of Helical Plasma Research, National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan)

2013-11-15

142

Nanostructured hydrophobic DC sputtered inorganic oxide coating for outdoor glass insulators  

Science.gov (United States)

We report the structural, optical and electrical properties of nanostructured hydrophobic inorganic hafnium oxide coating for outdoor glass insulator using DC sputtering technique to combat contamination problem. The properties were studied as a function of DC power. The characterization of the films was done using X-ray diffraction, EDS, surface profilometer, AFM, impedance analyser and water contact angle measurement system. The DC power was varied from 30 to 60 W and found to have a great impact on the properties of hafnium oxide. All the deposited samples were polycrystalline with nanostructured hydrophobic surfaces. The intensity of crystallinity of the film was found to be dependent on sputtering power and hydrophobicity was correlated to the nanoscale roughness of the films. The optical property reveals 80% average transmission for all the samples. The refractive index was found in the range of 1.85-1.92, near to the bulk value. The band gap calculated from transmission data was >5.3 eV for all deposited samples ensuring dielectric nature of the films. Surface energy calculated by two methods was found minimum for the film deposited at 50 W sputtering power. The resistivity was also high enough (˜104 ? cm) to hinder the flow of leakage current through the film. The dielectric constant (?) was found to be thickness dependent and also high enough (?max = 23.12) to bear the large electric field of outdoor insulators.

Dave, V.; Gupta, H. O.; Chandra, R.

2014-03-01

143

Genetic effect of zirconium oxide coating on osteoblast-like cells.  

Science.gov (United States)

Zirconium is widely used as material for prosthetic devices because its good mechanical and chemical properties. When exposed to oxygen, zirconium becomes zirconium oxide (ZrO(2)), which is biocompatible. ZrO(2) can be also prepared as a colloidal suspension and then used to coat surfaces. Zirconium oxide coating (ZrO(2)C) can potentially have specific biologic effects, and among them is bone formation related to implant osseointegration. How this biomaterial alters osteoblast activity to promote bone formation is poorly understood. We therefore attempted to address this question by using microarray techniques to identify genes that are differently regulated in osteoblasts exposed to ZrO(2)C. By using DNA microarrays containing 20,000 genes, we identified in osteoblast-like cell lines (MG-63) cultured with ZrO(2)C several genes whose expression was significantly upregulated or downregulated. The differentially expressed genes cover a broad range of functional activities: (a) cell cycle regulation, (b) signal transduction, (c) immunity, and (d) cytoskeleton component. The data reported are, to our knowledge, the first genetic portrait of ZrO(2)C effects. They can be relevant to better understand the molecular mechanism of bone regeneration and as a model for comparing other materials with similar clinical effects. PMID:17638321

Sollazzo, Vincenzo; Palmieri, Annalisa; Pezzetti, Furio; Bignozzi, Carlo Alberto; Argazzi, Roberto; Massari, Leo; Brunelli, Giorgio; Carinci, Francesco

2008-02-01

144

Reconstruction mechanisms of tantalum oxide coatings with low concentrations of silver for high temperature tribological applications  

Science.gov (United States)

Silver tantalate (AgTaO3) coatings have been found to exhibit outstanding tribological properties at elevated temperatures. To understand the mechanisms involved in the tribological behavior of the Ag-Ta-O system, tantalum oxide coatings with a small content of silver were produced to investigate the metastable nature of this self-lubricating material. The coatings were produced by unbalanced magnetron sputtering, ball-on-disk wear tested at 750 °C, and subsequently characterized by X-ray diffraction, Scanning Auger Nanoprobe, cross-sectional Scanning Electron Microscopy, and Transmission Electron Microscopy. Complementary molecular dynamic simulations were carried out to investigate changes in the chemical and structural properties at the interface due to sliding for films with varying silver content. Both the experimental characterization and the theoretical modeling showed that silver content affects friction and wear, through the role of silver in film reconstruction during sliding. The results suggest that the relative amount of silver may be used to tune film performance for a given application.

Stone, D. S.; Gao, H.; Chantharangsi, C.; Paksunchai, C.; Bischof, M.; Martini, A.; Aouadi, S. M.

2014-11-01

145

Selection of a Commercial Anode Oxide Coating for Electro-oxidation of Cyanide  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Este trabalho apresenta um estudo do desempenho de dois anodos comerciais de óxidos de metais nobres (DSA®) no processo eletroquímico para a oxidação de cianetos. Os revestimentos estudados foram 70TiO2/30RuO2 e 55Ta2O5/45IrO2, em um substrato de Ti. A eficiência dos dois materiais no processo de el [...] etrooxidação de cianeto livre foi comparada usando a voltametria linear e a eletrólise a potencial constante. O eletrodo 70TiO2/30RuO2 apresentou a melhor eficiência na eletrooxidação de cianetos livres. Abstract in english This paper presents a study of the performance of two commercial dimensionally stable anode (DSA®) oxide coatings in the electrochemical process for cyanide oxidation. The coatings studied were 70TiO2/30RuO2 and 55Ta2O5/45IrO2, on Ti substrate. The efficiency of both materials in the electro-oxidati [...] on of free cyanide was compared using linear voltammetry and electrolysis at constant potential. The 70TiO2/30RuO2 electrode shows a better performance in the electro-oxidation of free cyanide.

Marcos Roberto V., Lanza; Rodnei, Bertazzoli.

2002-06-01

146

Antibacterial activity and cytocompatibility of titanium oxide coating modified by iron ion implantation.  

Science.gov (United States)

In this work, zero valent iron nanoparticles (Fezero-NPs) and iron oxide nanoparticles (Feox-NPs) were synthesized at the subsurface and surface regions of titanium oxide coatings (TOCs) by plasma immersion ion implantation. This novel Fe-NPs/TOC system showed negligible iron releasing, great electron storage capability and excellent cytocompatibility in vitro. Importantly, the system showed selective antibacterial ability which can kill Staphylococcus aureus under dark conditions but has no obvious antibacterial effect against Escherichia coli. Owing to a bipolar Schottky barrier between Fezero-NPs/TOC and Fezero-NPs/Feox-NPs, electrons could be captured by the Fezero-NPs bounded at the subsurface region of the coating. This electron storage capability of the Fe-NPs/TOC system induced extracellular electron transportation and accumulation of adequate valence-band holes (h(+)) at the external side, which caused oxidation damage to S. aureus cells in the dark. No obvious biocide effect against E. coli resulted from lack of electron transfer ability between E. coli and substrate materials. This work may open up a novel and controlled strategy to design coatings of implants with antibacterial ability and cytocompatibility for medical applications. PMID:24914826

Tian, Yaxin; Cao, Huiliang; Qiao, Yuqin; Meng, Fanhao; Liu, Xuanyong

2014-10-01

147

Annealing effects on microstructure and mechanical properties of chromium oxide coatings  

International Nuclear Information System (INIS)

Reactive radio frequency magnetron sputter-deposited chromium oxide coatings were annealed at different temperatures and times. The influence of annealing temperature on the microstructure, surface morphology and mechanical properties was examined by X-ray diffraction, nanoindentation, pin-on-disc wear and scratch tests, respectively. X-ray results show that the chromium oxide sputtered at room temperature in low oxygen flux is primarily amorphous. Annealing below 400 deg. C did not cause much change, while annealing at higher temperature of 500 deg. C caused a significant change in microstructure and mechanical properties. Hardness increased from 12.3 GPa to 26 GPa, and the wearability improved with higher annealing temperature due to the formation of crystalline Cr2O3 phase, which occurs at 470 deg. C. Annealing time had little effect on mechanical properties and microstructure, although coating surface roughness increased with a longer annealing time. Coating adhesion was improved by annealing, due to residual stress relief and possible interfacial interdiffusion

148

Deuterium permeation through erbium oxide coatings on RAFM steels by a dip-coating technique  

Science.gov (United States)

A tritium permeation barrier is a promising solution for the problems of tritium loss and radiological safety in fusion blanket systems. In recent years, erbium oxide coatings have shown remarkable permeation reduction factors. One of the remaining issues for the coatings is the establishment of plant-scale fabrication. In this study, erbium oxide thin films have been fabricated by a dip-coating technique, which has the potential to coat a complex-shaped substrate, and deuterium permeation behavior in the coatings has been examined. Crack-free coatings were formed on a reduced activation ferritic/martensitic steel F82H substrate by use of a withdrawal speed of 1.0-1.4 mm s-1 and a heat-treatment process in hydrogen with moisture. In deuterium permeation experiments, a 0.2-?m-thick coating on both sides of the substrate showed a reduction factor of 600-700 in comparison with a F82H substrate below 873 K; however, the coating degraded at above 923 K because of crack formation. A double-coated sample indicated a reduction factor of up to 2000 and did not degrade at up to 923 K. The driving pressure dependence of the deuterium permeation flux indicated that the permeation tended to be limited by surface reactions at low temperatures. Optimization of the number of layers has the possibility to reduce degradation at high temperatures while maintaining high permeation reduction factors.

Chikada, Takumi; Naitoh, Shunya; Suzuki, Akihiro; Terai, Takayuki; Tanaka, Teruya; Muroga, Takeo

2013-11-01

149

Deuterium permeation through erbium oxide coatings on RAFM steels by a dip-coating technique  

International Nuclear Information System (INIS)

A tritium permeation barrier is a promising solution for the problems of tritium loss and radiological safety in fusion blanket systems. In recent years, erbium oxide coatings have shown remarkable permeation reduction factors. One of the remaining issues for the coatings is the establishment of plant-scale fabrication. In this study, erbium oxide thin films have been fabricated by a dip-coating technique, which has the potential to coat a complex-shaped substrate, and deuterium permeation behavior in the coatings has been examined. Crack-free coatings were formed on a reduced activation ferritic/martensitic steel F82H substrate by use of a withdrawal speed of 1.0–1.4 mm s?1 and a heat-treatment process in hydrogen with moisture. In deuterium permeation experiments, a 0.2-?m-thick coating on both sides of the substrate showed a reduction factor of 600–700 in comparison with a F82H substrate below 873 K; however, the coating degraded at above 923 K because of crack formation. A double-coated sample indicated a reduction factor of up to 2000 and did not degrade at up to 923 K. The driving pressure dependence of the deuterium permeation flux indicated that the permeation tended to be limited by surface reactions at low temperatures. Optimization of the number of layers has the possibility to reduce degradation at high temperatures while maintaining high permeation reduction factors

150

Functionalization of FeCo alloy nanoparticles with highly dielectric amorphous oxide coatings  

Science.gov (United States)

FeCo alloy nanoparticles have been prepared by using a two step modified polyol process using Fe(II) chloride and Co acetate tetrahydrate as Fe and Co metal precursors. Tetraethyl silicate, aluminum isopropoxide, and zirconium(IV) acetyl acetonate were used to make amorphous SiO2, Al2O3, and ZrO2 coatings, respectively. X-ray diffraction studies showed that there are no crystalline peaks corresponding to SiO2, Al2O3, and ZrO2 because the oxide coatings of the FeCo core are amorphous in nature. The scanning electron micrograph analysis depicted the cubic nature of the particles with mean particle size of about 45nm. The maximum saturation magnetization of 205emu /g was achieved at 300 and 4K. FeCo nanocomposites were screen printed as films and aligned by using an external magnetic field of 10kOe. The microwave properties measured by in-plane ferromagnetic resonance at various frequencies indicate a minimum linewidth of ?3700Oe.

Nguyen, Q.; Chinnasamy, C. N.; Yoon, S. D.; Sivasubramanian, S.; Sakai, T.; Baraskar, A.; Mukerjee, S.; Vittoria, C.; Harris, V. G.

2008-04-01

151

Titanium-nitride-oxide-coated Titan-2 bioactive coronary stent: a new breakthrough in interventional cardiology.  

Science.gov (United States)

The introduction of drug-eluting stents (DES) has revolutionized the field of interventional cardiology, since it has reduced the incidence of restenosis by 50% to 70%. However, recent worrisome data from registries and meta-analyses emphasized higher rates of late and very late stent thrombosis associated with DES. The recently introduced titanium-nitride-oxide-coated stent bioactive stent (Titan-2) was manufactured by a proprietary process to coat titanium-nitride-oxide on the surface of the stainless steel stent, based on a plasma technology using the nano-synthesis of gas and metal. This late-breaking stent has demonstrated an excellent biocompatibility, as reflected by lower rates of platelet aggregation and fibrin deposition, and better endothelialization. Preclinical and clinical trials and registries involving real-life unselected populations have shown a low rate of major adverse cardiac events at long-term follow-up. Restenosis rates were comparable with those of DES, with very rare stent thrombosis. Equally favorable results have been obtained in patients at high-risk of in-stent restenosis, such as diabetics and those with small coronary arteries. Results in patients presenting with acute coronary syndrome have been again comparable to those of DES, with tendency to lower rates of myocardial infarction and stent thrombosis. Comparisons with second generation drug-eluting stents have also been promising. PMID:21983305

Karjalainen, P; Nammas, W

2011-10-01

152

Evaluation of cerium oxide coated Cu cermets as inert anodes for aluminum electrowinning  

Energy Technology Data Exchange (ETDEWEB)

Cu/NiFe{sub 2}O{sub 4} cermets were evaluated, with and without an in-situ deposited CEROX (TM; cerium oxide) coating, in 100 h laboratory A1 electrowinning tests. Bath ratio and current density were varied between tests and corrosion was determined by contamination of the aluminum and cryolite by cermet components (Cu, Fe, and Ni). Higher bath ratios of 1.5 to 1.6 led to less corrosion and thicker CEROX coatings. Lower current densities led to slightly less corrosion but much less oxidation of the Cu cermet substrate. At identical test conditions, the corrosion of the CEROX coated cermets was 1/7 that of an uncoated cermet. Corrosion was increased in CEROX coated cermets tested under unsaturated alumina conditions. The electrical conductivity of the CEROX coating was measured to be {approximately}0.2 ohm{sup {minus}1}cm{sup {minus}1}, resulting in a slight voltage penalty, depending on the thickness of the coating.

1992-08-01

153

Zn sorption mechanisms onto sheathed Leptothrix discophora and the impact of the nanoparticulate biogenic Mn oxide coating.  

Science.gov (United States)

Zinc sorption on sheathed Leptothrix discophora bacterium, the isolated extracellular polymeric substances (EPS) sheath, and Mn oxide-coated bacteria was investigated with macroscopic and spectroscopic techniques. Complexation with L. discophora was dominated by the outer membrane phosphoryl groups of the phospholipid bilayer while sorption to isolated EPS was dominated by carboxyl groups. Precipitation of nanoparticulate Mn oxide coatings on the cell surface increased site capacity by over twenty times with significant increase in metal sorption. XAS analysis of Zn sorption in the coated system showed Mn oxide phase contributions of 18 to 43% through mononuclear inner-sphere complexes. The coordination environments in coprecipitation samples were identical to those of sorption samples, indicating that, even in coprecipitation, Zn is not incorporated into the Mn oxide structure. Rather, through enzymatic oxidation by L. discophora, Mn(II) is oxidized and precipitated onto the biofilm providing a large surface for metal sequestration. The nanoparticulate Mn oxide coating exhibited significant microporosity (75%) suggesting contributions from intraparticle diffusion. Transient studies conducted over 7 months revealed a 170% increase in Zn loading. However, the intraparticle diffusivity of 10(-19) cm(2) s(-1) is two orders of magnitude smaller than that for abiotic Mn oxide which we attribute to morphological changes such as reduced pore sizes in the nanoparticulate oxide. Our results demonstrate that the cell-bound Mn oxide particles can sorb significant amounts of Zn over long periods of time representing an important surface for sequestration of metal contaminants. PMID:19268965

Boonfueng, Thipnakarin; Axe, Lisa; Yee, Nathan; Hahn, Dittmar; Ndiba, Peter K

2009-05-15

154

Zn Sorption Mechanisms onto Sheathed Leptothrix Discophora and the Impact of the Nanoparticulate Biogenic Mn Oxide Coating  

Energy Technology Data Exchange (ETDEWEB)

Zinc sorption on sheathed Leptothrix discophora bacterium, the isolated extracellular polymeric substances (EPS) sheath, and Mn oxide-coated bacteria was investigated with macroscopic and spectroscopic techniques. Complexation with L. discophora was dominated by the outer membrane phosphoryl groups of the phospholipid bilayer while sorption to isolated EPS was dominated by carboxyl groups. Precipitation of nanoparticulate Mn oxide coatings on the cell surface increased site capacity by over twenty times with significant increase in metal sorption. XAS analysis of Zn sorption in the coated system showed Mn oxide phase contributions of 18 to 43% through mononuclear inner-sphere complexes. The coordination environments in coprecipitation samples were identical to those of sorption samples, indicating that, even in coprecipitation, Zn is not incorporated into the Mn oxide structure. Rather, through enzymatic oxidation by L. discophora, Mn(II) is oxidized and precipitated onto the biofilm providing a large surface for metal sequestration. The nanoparticulate Mn oxide coating exhibited significant microporosity (75%) suggesting contributions from intraparticle diffusion. Transient studies conducted over 7 months revealed a 170% increase in Zn loading. However, the intraparticle diffusivity of 10{sup -19} cm{sup 2} s{sup -1} is two orders of magnitude smaller than that for abiotic Mn oxide which we attribute to morphological changes such as reduced pore sizes in the nanoparticulate oxide. Our results demonstrate that the cell-bound Mn oxide particles can sorb significant amounts of Zn over long periods of time representing an important surface for sequestration of metal contaminants.

Boonfueng, T.; Axe, L; Yee, N; Hahn, D; Ndiba, P

2009-01-01

155

Hydrophobic Porous Material Adsorbs Small Organic Molecules  

Science.gov (United States)

Composite molecular-sieve material has pore structure designed specifically for preferential adsorption of organic molecules for sizes ranging from 3 to 6 angstrom. Design based on principle that contaminant molecules become strongly bound to surface of adsorbent when size of contaminant molecules is nearly same as that of pores in adsorbent. Material used to remove small organic contaminant molecules from vacuum systems or from enclosed gaseous environments like closed-loop life-support systems.

Sharma, Pramod K.; Hickey, Gregory S.

1994-01-01

156

Magnetic graphene composites as both an adsorbent for sample enrichment and a MALDI-TOF MS matrix for the detection of nitropolycyclic aromatic hydrocarbons in PM2.5.  

Science.gov (United States)

A simple and rapid method that uses synthesized magnetic graphene composites as both an adsorbent for enrichment and as a matrix in MALDI-TOF MS analysis was developed for the detection of nitropolycyclic hydrocarbons (nitro-PAHs) in PM2.5 samples. Three nitro-PAHs were detected down to sub pg ?L(-1) levels based on calculations from an instrumental signal-to-noise better than 3, which shows the feasibility of using the new materials in MALDI-TOF MS as a potential powerful analytical approach for the analysis of nitro-PAHs in PM2.5 samples. PMID:25627557

Zhang, Jiangang; Zhang, Li; Li, Ruijin; Hu, Di; Ma, Nengxuan; Shuang, Shaomin; Cai, Zongwei; Dong, Chuan

2015-03-01

157

Influence of mechanical abrasion of carbon adsorbents on aerodynamic resistance of filters of system of ventilation of NPS  

International Nuclear Information System (INIS)

Influence of mechanical abrasion of granules on aerodynamic resistance of different carbon adsorbents at conditions similar to work of filters AU-1500 is studied. The change of fractional composition of the probed adsorbents by abrasion is determined. The obtained experimental data allow making conclusion about practicability using mixture of adsorbent Norit with different fractional composition for renewal of adsorbers of ventilation system of NPS.

158

Performance comparison of dye-sensitized solar cells by using different metal oxide- coated TiO2 as the photoanode  

Directory of Open Access Journals (Sweden)

Full Text Available In order to increase the conversion efficiency of dye-sensitized solar cells, TiO2 photoanode surface is often covered with a metal oxide layer to form a core-shell composite structure. Different metal oxide coating on TiO2 as composite photoanodes can affect the cell efficiency variously. However, there still lacks the crosswise comparison among the effects of different metal oxides on TiO2 photoanode. In this study, TiO2 was coated with Al2O3, CaO, ZnO, MgO, Fe2O3 or Bi2O3 separately by liquid phase deposition method. The results indicated that cells with TiO2/Al2O3, TiO2/ZnO, TiO2/CaO, or TiO2/MgO composite film as a photoanode had higher conversion efficiency than those with un-coated TiO2 films. TiO2/Al2O3 showed the highest efficiency and TiO2/CaO ranked second. On the contrary, cells with TiO2/Bi2O3 or TiO2/Fe2O3 composite film as a photoanode had lower conversion efficiency than those with un-coated TiO2 films. The mechanism of the cell efficiency change was also investigated. To get higher conversion efficiency, matched energy level of the metal oxide with TiO2 is the first prerequisite, and then the optimum coating thickness is also a necessary condition.

Sun Xuhui

2014-01-01

159

Performance comparison of dye-sensitized solar cells by using different metal oxide- coated TiO2 as the photoanode  

Science.gov (United States)

In order to increase the conversion efficiency of dye-sensitized solar cells, TiO2 photoanode surface is often covered with a metal oxide layer to form a core-shell composite structure. Different metal oxide coating on TiO2 as composite photoanodes can affect the cell efficiency variously. However, there still lacks the crosswise comparison among the effects of different metal oxides on TiO2 photoanode. In this study, TiO2 was coated with Al2O3, CaO, ZnO, MgO, Fe2O3 or Bi2O3 separately by liquid phase deposition method. The results indicated that cells with TiO2/Al2O3, TiO2/ZnO, TiO2/CaO, or TiO2/MgO composite film as a photoanode had higher conversion efficiency than those with un-coated TiO2 films. TiO2/Al2O3 showed the highest efficiency and TiO2/CaO ranked second. On the contrary, cells with TiO2/Bi2O3 or TiO2/Fe2O3 composite film as a photoanode had lower conversion efficiency than those with un-coated TiO2 films. The mechanism of the cell efficiency change was also investigated. To get higher conversion efficiency, matched energy level of the metal oxide with TiO2 is the first prerequisite, and then the optimum coating thickness is also a necessary condition.

Xuhui, Sun; Xinglan, Chang; Wanquan, Tuo; Dong, Wang; Kefei, Li

2014-03-01

160

Reduced bleaching in organic nanofibers by bilayer polymer/oxide coating  

DEFF Research Database (Denmark)

Organic semiconductors based on small molecules are receiving increased attention due in part to their application potential within various opto-electronic devices such as transistors, light-emitting diodes, and solar cells, but also due to their relative ease of processing, low price, and tunability through synthetic chemistry. Phenylene-based molecules such as para-hexaphenylene (p6P) are of particular interest due to their ability to self-assemble into elongated, nanoscale, crystalline aggregates or ‘nanofibers’ [1]. Such nanofibers can emit polarized light with a highly anisotropic emission profile, can act a sub-wavelength optical waveguides, and could form the basis for a new type of miniature OLEDs. However, p6P molecules exhibit a characteristic photoinduced reaction (bleaching) resulting in a decrease of luminescence intensity upon UV light exposure [2], which could render the technological use of the nanofibers problematic. In order to investigate the photoinduced reaction in nanofibers, optical bleaching experiments have been performed by irradiating both pristine and coated nanofibers with UV light. Oxide coating materials (SiOx [2] and Al2O3) were applied onto p6P nanofibers. These treatments caused a reduction of the bleaching reaction but in addition, the nanofiber luminescence spectrum was significantly altered. It was observed that some polymer coatings (P(TFE-PDD), and PMMA) do not interfere with the luminescence spectrum from the p6P but are not effective in stopping the bleaching. Bilayer coatings with first a polymer material, which should work as a protection layer to avoid modifications of the p6P luminescence spectrum, and second an oxide layer used as oxygen blocker were tested and it was found that a particular bilayer polymer/oxide combination results in a significant reduction of bleaching without affecting significantly the emission spectrum from the nanofibers.

Tavares, Luciana; Kjelstrup-Hansen, Jakob

 
 
 
 
161

Polyacrylate adsorbents for the selective adsorption of cholesterol-rich lipoproteins from plasma or blood  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Polyacrylate (PAA) adsorbents selectively bind low density lipoproteins (LDL) from human plasma and blood, whereas very low density lipoproteins (VLDL) are only minimally adsorbed. The adsorption of cholesterol-rich lipoproteins to PAA adsorbents is related to the molecular weight (mw) of the polyanion ligand. Ca++ and Mg++ inhibit the binding of LDL to PAA adsorbents. The chemical composition of the organic hardgels of the adsorbents does not have an influence on adsorption. The selecti...

Heuck, Claus-chr

2011-01-01

162

PENGARUH KOMPOSOSI LAPISAN PADA PERMUKAAN GLOBULA MINYAK EMULSI SEBELUM PENGERINGAN SEMPROT TERHADAP SIFAT-SIFAT MIKROKAMSUL TRIGLISERIDA KAYA ASAM LEMAK W-3 [The Effect of the Composition of Adsorbed Layer at Globule Interface of ?-3 Fatty Acids Enriched Triglyceride Prior to Spray Drying on its Microcapsule Properties  

Directory of Open Access Journals (Sweden)

Full Text Available Emulsification is the critical factor in microencapsulation by spray drying method. Sodium caseinate is a protein with good emulsifying properties. The properties could be improved by phospholipids addition in the emulsification. Phospholipids addition which stabilized oil globule might change the composition of adsorbed layer.This research was conducted to analyze the changes in composition at oil globule interface by analyzing emulsion systems of triglyceride enriched by ?-3 fatty acids at 5% (w/v stabilized by sodium caseinate (10% w/v and addition of phospholipids at 0; 0,5; 1,0; 1,5; 2,0; and 2,5% (w/v. The changes in composition of adsorbed layer could be determined from the changes in phospholipids and adsorbed protein concentrations at oil globule interface. Analyses were done to measure the possibility of casein-phospholipids complex, phospholipids and protein adsorption concentration at interface, and adsorbed protein.The increase of phospholipids concentration in the emulsions stabilized by sodium caseinate changed the composition of adsorbed layer at interface. There was phospholipids increase and adsorbed protein decrease at oil globule interface. These changes were caused by casein-phospholipids complex which that decreased surface activity and displacement protein by phospholipids that was adsorbed at oil globule interface.Changes of composition of casein-phospholipids at oil globule prior to microcapsulation process caused changes in the properties of microcapsule produced. The increasing phospholipids and decreasing casein concentrations at oil globule interface decreased the quality of the microcapsule, including decreasing in microencapsulation efficiency, in oxidative stability, and decreasing in EPA+DHA content.

Moch Adnan2

2005-04-01

163

The impact of the mass density on selected optical and non-optical properties of oxide coatings  

Science.gov (United States)

The density of optical coatings is one of the most crucial material-related parameters in interference coating science and technology. It has an impact on the refractive index, the transparency range, and the mechanical stress of a coating material. This tutorial provides a background on the classical theory relating the coating density to the mentioned parameters. Simple models are presented that highlight the correlations between optical constants, stress, and shifting behavior of different oxide coatings. Comparison with the experiment is performed on the basis of numerous experimental data, which stem from hafnium oxide, zirconium oxide, tantalum pentoxide, and silicon dioxide.

Stenzel, Olaf

2014-02-01

164

Effect of the oxide loading on the surface characteristics of LaNio3 oxide coated electrodes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The LaNiO3 perovskite-type oxide is one of the most tested anode for the oxygen evolution reaction in alkaline solutions. It is well established that the oxide preparation conditions and the electrode fabrication are key factors to control the electrochemical behaviour of oxide coatings. In a previous work the authors studied the influence of preparation conditions of the oxide and support type on the electrochemical behaviour of Ni foam coated LaNiO3 electrodes. Ni foam was selected as suppo...

Soares, C. O.; Silva, R. A.; Carvalho, M. D.; Jorge, M. E. Melo; Gomes, A.; Rangel, C. M.; Pereira, M. I. Da Silva

2011-01-01

165

Adsorption of phosphoric acid on niobium oxide coated cellulose fiber: preparation, characterization and ion exchange property  

International Nuclear Information System (INIS)

The preparation procedures for a hybrid organic-inorganic cellulose-niobium oxide (Cel/Nb2O5) and its derivative, Cel/Nb2O5/phosphate, are described. The precursor reagent of the metal oxide was the very convenient water soluble niobium oxalate compound, NH4[NbO(C2O4)2)(H2O)2].nH2 O. Phosphate ion was adsorbed on the Cel/Nb2O5 by immersing this solid in an aqueous solution of phosphoric acid. Textural analyses carried out by using scanning electron microscopy (SEM) connected to an energy dispersive detector (EDS) revealed that the niobium oxide particles are, within the magnification used, uniformly dispersed on the cellulose matrix surface. Phosphoric acid is adsorbed on the material surface through the Nb-O-P linkage. The X-ray photoelectron and 31P NMR spectra showed that the adsorbed phosphate on the surface is the (H2PO4)- species. The ion exchange isotherms obtained using the material Cel/Nb2O5/H2PO4- showed good affinity for retaining Na+, K+ and Ca2+ when in contact with these ions in an aqueous solution. (author)

166

Extraction of methocarbamol from human plasma with a polypyrrole/multiwalled carbon nanotubes composite decorated with magnetic nanoparticles as an adsorbent followed by electrospray ionization ion mobility spectrometry detection.  

Science.gov (United States)

In this work, a polypyrrole/multiwalled carbon nanotubes composite decorated with Fe3 O4 nanoparticles was chemically synthesized and applied as a novel adsorbent for the extraction of methocarbamol from human plasma. Electrospray ionization ion mobility spectrometry was used for the determination of the analyte. The properties of the magnetic-modified adsorbent were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform IR spectroscopy, and X-ray diffraction. The effects of experimental parameters on the extraction efficiency of the sorbent were investigated. Under the optimized conditions, the linear dynamic range was found to be 2-150 ng/mL with the detection limit of 0.9 ng/mL. The relative standard deviation was 5.3% for three replicate measurements of methocarbamol in plasma sample. The extraction efficiency of the sorbent for the determination of different drugs with various polarities was also compared to that of Fe3 O4 -polypyrrole and Fe3 O4 -multiwalled carbon nanotubes sorbents. Finally, the method was used for the determination of methocarbamol in blood samples. PMID:25243817

Saraji, Mohammad; Khayamian, Taghi; Hashemian, Zahra

2014-12-01

167

Adsorption of phosphoric acid on niobium oxide coated cellulose fiber: preparation, characterization and ion exchange property  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Os procedimentos para a preparação do híbrido orgânico-inorgânico celulose-óxido de nióbio (Cel/Nb2O5) e o seu derivado, Cel/Nb2O5/fosfato, são descritos. O reagente precursor do óxido metálico foi o composto oxalato de nióbio, NH4[NbO(C2O4)2)(H 2O)2].nH2 O, muito conveniente por ser solúvel em água [...] . O íon fostato foi adsorvido sobre o Cel/Nb2O5 pela imersão deste sólido em uma solução de acido fosfórico. As análises de textura efetuadas usando a microscopia eletrônica de varredura (MEV) conectada a um detector de energia dispersiva (EDS) revelaram que as partículas do óxido de nióbio, dentro da resolução utilizada, são uniformemente dispersas na superfície da matriz de celulose. O ácido fosfórico é adsorvido sobre a superfície do material através da formação da ligação Nb-O-P. Os espectros de fotoelétrons de raios-X e de ressonância magnética nuclear de 31P mostraram que o fosfato adsorvido na superfície é a espécie H2PO4-. As isotermas de troca iônica obtidas utilizando-se o material mostraram uma boa afinidade na retenção de Na+, K+ e Ca2+ quando em contacto com estes íons em solução aquosa. Abstract in english The preparation procedures for a hybrid organic-inorganic cellulose-niobium oxide (Cel/Nb2O5) and its derivative, Cel/Nb2O5/phosphate, are described. The precursor reagent of the metal oxide was the very convenient water soluble niobium oxalate compound, NH4[NbO(C2O4)2)(H 2O)2].nH2 O. Phosphate ion [...] was adsorbed on the Cel/Nb2O5 by immersing this solid in an aqueous solution of phosphoric acid. Textural analyses carried out by using scanning electron microscopy (SEM) connected to an energy dispersive detector (EDS) revealed that the niobium oxide particles are, within the magnification used, uniformly dispersed on the cellulose matrix surface. Phosphoric acid is adsorbed on the material surface through the Nb-O-P linkage. The X-ray photoelectron and 31P NMR spectra showed that the adsorbed phosphate on the surface is the (H2PO4)- species. The ion exchange isotherms obtained using the material Cel/Nb2O5/H2PO4- showed good affinity for retaining Na+, K+ and Ca2+ when in contact with these ions in an aqueous solution.

Flávio A., Pavan; Maria Suzana P., Francisco; Richard, Landers; Yoshitaka, Gushikem.

2005-08-01

168

Ionogenic adsorbents based on local raw materials for radiation protection  

International Nuclear Information System (INIS)

The successful management of uranium wastes and creating the conditions for effective rehabilitation activities require special adsorbents capable of holding on the surface complexes, including radioactive elements. Currently tested and have shown promising synthetic adsorbents based pitted apricot fruits and other fruit plants. This report presents data for the establishment of ionic type available adsorbents based on Tajikistan coal. As the base for the creation of this type of adsorbent were taken the coal of the 'Ziddi' deposits. As follows from our data on the chemical composition, the studied coals contain more than 20% of the ash. According to the available literature theses ashes contains various minerals compositions that can form the adsorbent's active surface. Thus, the model for this type of activated carbon can serve as a mixture of zeolite, ion exchange resins and activated carbon itself.

169

Adsorbents for radioactive cesium  

International Nuclear Information System (INIS)

To promote decontamination program of the Cs 137-contaminated soils in the area of Fukushima Daiichi Nuclear Power Plants after the reactor accident, quantitative adsorption data of the adsorbents such as synthesized zeolite A, bentonite, ferrocyanide-Ti(IV) and -Ti(III), montmorillonite, synthesized saponite, etc for alkali metal ions (mmol/g) were studied. A 10 ml solution of alkali metal ions (Cs+, K+, Na+ and Li+ ions) containing 0.1 g of the adsorbent was stirred for 10 min and decrease in the concentration of each ions determined by ion-chromatography. Pre-treatment of absorbents with NaCl or HNO3 was also investigated to conclude that the most effective adsorbent for selective removal of cesium ions among studied is montmorillonite. (S. Ohno)

170

Regenerative adsorbent heat pump  

Science.gov (United States)

A regenerative adsorbent heat pump process and system is provided which can regenerate a high percentage of the sensible heat of the system and at least a portion of the heat of adsorption. A series of at least four compressors containing an adsorbent is provided. A large amount of heat is transferred from compressor to compressor so that heat is regenerated. The process and system are useful for air conditioning rooms, providing room heat in the winter or for hot water heating throughout the year, and, in general, for pumping heat from a lower temperature to a higher temperature.

Jones, Jack A. (Inventor)

1991-01-01

171

Clustering in adsorbed films  

International Nuclear Information System (INIS)

Recently, J.G. Dash has shown that adsorption isotherms can show distincts types of behavior. In class I the bulk vapor pressure is reached asymptotically for an infinite adsorbed amount; in Class II it is reached for a finite amount; in Class III no adsorption takes place at all. These possibilities can also be derived by a simple discussion of the possible forms of the free energy as function of the thickness of the adsorbed film. The question of clustering, i.e. the formation of drops, is also discussed

172

Screening the toxicity of phosphorous-removal adsorbents using a bioluminescence inhibition test.  

Science.gov (United States)

When found in excess, phosphorus (P) has been linked to surface water eutrophication. As a result, adsorbents are now used in P remediation efforts. However, possible secondary toxicological impacts on the use of new materials for P removal from surface water have not been reported. This study evaluated the toxicity of adsorbent materials used in the removal of P from surface water including: fly ash, bottom ash, alum sludge, a proprietary mix of adsorbents, and a proprietary engineered material. Toxicity screening was conducted by performing solid-liquid extractions (SLEs) followed by the bacterial bioluminescence inhibition test with a Microtox® M500. Of the materials tested, the samples extracted at lower pH levels demonstrated higher toxicity. The material exhibiting the most toxic response was the iron and aluminum oxide coated engineered material registering a 66-67% 15-min EC50 level for pH 4 and 5 SLEs, respectively. However, for SLEs prepared at pH 7, toxic effects were not detected for this engineered material. Fly ash and bottom ash demonstrated between 82 and 84% 15-min EC50 level, respectively, for pH 4 SLE conditions. Dried alum sludge and the proprietary mix of adsorbents were classified as having little to no toxicity. © 2014 Wiley Periodicals, Inc. Environ Toxicol, 2014. PMID:25348491

Duranceau, Steven J; Biscardi, Paul G; Barnhill, Danielle K

2014-10-28

173

PENGARUH KOMPOSOSI LAPISAN PADA PERMUKAAN GLOBULA MINYAK EMULSI SEBELUM PENGERINGAN SEMPROT TERHADAP SIFAT-SIFAT MIKROKAMSUL TRIGLISERIDA KAYA ASAM LEMAK W-3 [The Effect of the Composition of Adsorbed Layer at Globule Interface of ?-3 Fatty Acids Enriched Triglyceride Prior to Spray Drying on its Microcapsule Properties  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Emulsification is the critical factor in microencapsulation by spray drying method. Sodium caseinate is a protein with good emulsifying properties. The properties could be improved by phospholipids addition in the emulsification. Phospholipids addition which stabilized oil globule might change the composition of adsorbed layer.This research was conducted to analyze the changes in composition at oil globule interface by analyzing emulsion systems of triglyceride enriched by ?-3 fatty acids a...

Teti Estiasih1)*; Moch Adnan2); Tranggono2); Suparmo2)

2005-01-01

174

Electron-microscopic imaging of electrolytic oxide coatings on AA2214; Elektronenmikroskopische Darstellung elektrolytischer Oxidschichten auf AA2214  

Energy Technology Data Exchange (ETDEWEB)

The alloy AA2214 is one of the medium to high-strength age-hardening forging alloys which play an important role as structural materials in the aircraft industry. For purposes of protection against corrosion and wear these alloys are very often anodized. Transmission electron microscopic studies on coatings anodized by sulfuric acid have clearly shown the effect of anodizing voltage on pore size. Intermetallic phases occurring in the microstructures of such materials were shown to be largely broken up during the anodizing process. Small proportions of alloy elements were, however, still detectable in the oxide. During the subsequent sealing process these open pores are closed and after only 15 minutes the process is substantially completed, revealing no significant gradation of density throughout the thickness of the oxide coating. (orig.)

Schneider, Michael [Fraunhofer-Institut fuer Keramische Technologien und Systeme (IKTS), Dresden (Germany); Kuebel, Christian; Yezerska, Olga [Fraunhofer Institut fuer Fertigungstechnik und Angewandte Materialforschung (IFAM), Bremen (Germany); Viola, Alain; Augros, Myriam [Messier-Bugatti, Molsheim (France). Div. Freinage Aeronautic

2009-05-15

175

Characterization of hafnium oxide coatings on low activation martensitic steel at various O2/Ar flow ratios  

International Nuclear Information System (INIS)

Hafnium oxide coatings were prepared at various O2/Ar flow ratios by RF (radio frequency) magnetron sputtering on low activation Martensitic steel. The effects of O2/Ar flow ratio on the deposition rate and the properties of HfO2 are studied. The results show that the deposition rate decreases with increasing the O2/Ar flow ratio. Moreover, the coatings prepared at various O2/Ar flow ratios are compact and the main phase of the coatings is monoclinic. Additionally the coatings prepared at the O2/Ar ratios 0.7 and 1.2 were broken down under 1 MV/cm and show poor electrical insulation properties, while the coatings prepared at smaller O2/Ar flow ratios show better electrical insulation properties. (authors)

176

Alloy Films Deposited by Electroplating as Precursors for Protective Oxide Coatings on Solid Oxide Fuel Cells Metallic Interconnect Materials  

Energy Technology Data Exchange (ETDEWEB)

The successful development of stainless steel interconnects for intermediate temperature solid oxide fuel cells (SOFC) may be the materials breakthrough that makes SOFC technology truly commercial. Many of the ferritic stainless steels, however, suffer from a relatively high area specific resistance (ASR) after long exposure times at temperature and the Cr in the native oxide can evaporate and contaminate other cell components. Conductive coatings that resist oxide scale growth and chromium evaporation may prevent both of these problems. In the present study electrochemical deposition of binary alloys followed by oxidation of the alloy to form protective and conductive oxide layers is examined. Results are presented for the deposition of Mn/Co and Fe/Ni alloys via electroplating to form a precursor for spinel oxide coating formation. Analysis of the alloy coatings is done by SEM, EDS and XRD.

Johnson, Christopher; Gemmen, R.S.; Cross, Caleb

2006-10-01

177

Fabrication of mesoporous metal oxide coated-nanocarbon hybrid materials via a polyol-mediated self-assembly process  

Science.gov (United States)

After clarifying the formation mechanism of a typical metal glycolate precipitate, Ti glycolate, in a polyol-mediated synthesis using acetone as a precipitation medium, we describe a simple template-free approach based on an ethylene glycol-mediated synthesis to fabricate mesoporous metal oxide coated-nanocarbon hybrid materials including TiO2 coated-carbon nanotube (CNT), SnO2 coated-CNT, Cu2O/CuO coated-CNT and TiO2 coated-graphene sheet (GS). In the approach, metal oxide precursors, metal glycolates, were first deposited on CNTs or GSs, and subsequently transformed to the metal oxide coatings by pyrolysis or hydrolysis. By a comparison between the characterization of two TiO2-CNT hybrid materials using carboxylated CNTs and pristine CNTs without carboxyl groups, the driving force for initiating the deposition of metal glycolates on the carboxylated CNTs is confirmed to be the hydrogen bonding between the carboxyl groups and the polymer chains in metal glycolate sols. The electrochemical performances of the mesoporous TiO2 coated-carboxylated CNTs and TiO2-pristine CNT hybrid materials were investigated. The results show that the mesoporous TiO2 coated-carboxylated CNT with a uniform core-shell nanostructure exhibits substantial improvement in the rate performance in comparison with its counterpart from 0.5 C to 100 C because of its higher electronic conductivity and shorter diffusion path for the lithium ion. At the extremely high rate of 100 C, the specific capacity of TiO2 of the former reaches 85 mA h g-1, twice as high as that of the latter.After clarifying the formation mechanism of a typical metal glycolate precipitate, Ti glycolate, in a polyol-mediated synthesis using acetone as a precipitation medium, we describe a simple template-free approach based on an ethylene glycol-mediated synthesis to fabricate mesoporous metal oxide coated-nanocarbon hybrid materials including TiO2 coated-carbon nanotube (CNT), SnO2 coated-CNT, Cu2O/CuO coated-CNT and TiO2 coated-graphene sheet (GS). In the approach, metal oxide precursors, metal glycolates, were first deposited on CNTs or GSs, and subsequently transformed to the metal oxide coatings by pyrolysis or hydrolysis. By a comparison between the characterization of two TiO2-CNT hybrid materials using carboxylated CNTs and pristine CNTs without carboxyl groups, the driving force for initiating the deposition of metal glycolates on the carboxylated CNTs is confirmed to be the hydrogen bonding between the carboxyl groups and the polymer chains in metal glycolate sols. The electrochemical performances of the mesoporous TiO2 coated-carboxylated CNTs and TiO2-pristine CNT hybrid materials were investigated. The results show that the mesoporous TiO2 coated-carboxylated CNT with a uniform core-shell nanostructure exhibits substantial improvement in the rate performance in comparison with its counterpart from 0.5 C to 100 C because of its higher electronic conductivity and shorter diffusion path for the lithium ion. At the extremely high rate of 100 C, the specific capacity of TiO2 of the former reaches 85 mA h g-1, twice as high as that of the latter. Electronic supplementary information (ESI) available. See DOI: 10.1039/C4NR04254A

Feng, Bingmei; Wang, Huixin; Wang, Dongniu; Yu, Huilong; Chu, Yi; Fang, Hai-Tao

2014-11-01

178

Size selective hydrophobic adsorbent for organic molecules  

Science.gov (United States)

The present invention relates to an adsorbent formed by the pyrolysis of a hydrophobic silica with a pore size greater than 5 .ANG., such as SILICALITE.TM., with a molecular sieving polymer precursor such as polyfurfuryl alcohol, polyacrylonitrile, polyvinylidene chloride, phenol-formaldehyde resin, polyvinylidene difluoride and mixtures thereof. Polyfurfuryl alcohol is the most preferred. The adsorbent produced by the pyrolysis has a silicon to carbon mole ratio of between about 10:1 and 1:3, and preferably about 2:1 to 1:2, most preferably 1:1. The pyrolysis is performed as a ramped temperature program between about 100.degree. and 800.degree. C., and preferably between about 100.degree. and 600.degree. C. The present invention also relates to a method for selectively adsorbing organic molecules having a molecular size (mean molecular diameter) of between about 3 and 6 .ANG. comprising contacting a vapor containing the small organic molecules to be adsorbed with the adsorbent composition of the present invention.

Sharma, Pramod K. (Inventor); Hickey, Gregory S. (Inventor)

1997-01-01

179

Impact of surfactant-induced wettability alterations on DNAPL invasion in quartz and iron oxide-coated sand systems.  

Science.gov (United States)

Dense non-aqueous phase liquids (DNAPLs) present in the subsurface may contain surface active compounds that impact DNAPL migration and distribution. While a number of studies have revealed the role surface active compounds play in altering the wettability of quartz sand, few have considered the implications for other minerals common to contaminated sites. This study extends understanding of DNAPL/surfactant wettability to iron oxide surfaces. Specifically, quartz and iron oxide-coated sands in a tetrachloroethene (PCE)/water system containing the organic base (an organic molecule that acts as a base) dodecylamine (DDA) were compared at a variety of scales. Wettability of the minerals' surfaces, and the impact of wettability on capillary resistance to DNAPL entry, were assessed as a function of pH through: (i) advancing and receding contact angles, (ii) primary drainage capillary pressure-saturation experiments, and (iii) small, two-dimensional, flow cell experiments. The work revealed that, at neutral pH and under identical boundary capillary pressures, DNAPL invaded quartz sand but not iron oxide-coated sand; however, at low pH, DNAPL invaded both sands equally. These differences were demonstrated to be due to wettability alterations associated with the strength of attractive forces between DDA and the mineral surface, dictated by the isolectric point of the minerals and system pH. Observed differences in DNAPL invasion behavior were consistent with measured intrinsic contact angles and P(c)-S relationships, the latter requiring scaling by the operative contact angle inside the porous medium for a meaningful comparison. This study suggests that the distribution of minerals (and, more specifically, their isoelectric points), as well as the aqueous phase pH at a given site, may have a significant impact on the DNAPL source zone architecture. PMID:20880604

Molnar, Ian L; O'Carroll, Denis M; Gerhard, Jason I

2011-01-25

180

Sorptive removal of cobalt, strontium and cesium onto manganese and iron oxide-coated montmorillonite from groundwater  

International Nuclear Information System (INIS)

Applicability of montmorillonite, manganese oxide-coated montmorillonite (MOCM) and iron oxide-coated montmorillonite (IOCM) as backfill materials in permeable reactive barrier (PRB) to remediate contaminated groundwater was investigated. Single- and bi-solute competitive sorptions of Co, Sr and Cs were conducted. The Freundlich, Langmuir and Dubinin-Radushkevich models fitted the single-solute sorption data well (R2 > 0.95). Maximum sorption capacities (qmL) of Co and Sr predicted by the Langmuir model were in the order of MOCM (0.37 mmol/g for Co and 0.28 mmol/g for Sr) > montmorillonite (0.27 mmol/g for Co and 0.19 mmol/g for Sr) ? IOCM (0.23 mmol/g for Co and 0.21 mmol/g for Sr), while those of Cs were in the order of montmorillonite (1.11 mmol/g) > MOCM (0.68 mmol/g) > IOCM (0.62 mmol/g). In the bi-solute sorptions, the sorbed amount of one solute decreased due to the presence of the other competing metal ion. Langmuir model parameters for single-solute (qmL and bL) and bi-solute (qmL* and bL*) sorptions were compared to analyze the effect of competition between the metal ions. The competitive Langmuir (R2 > 0.81) and P-factor (R2 > 0.82) models predicted the bi-solute competitive sorption data well but not the SRS model (0.003 2 < 0.97). (author)

 
 
 
 
181

High temperature cobalt adsorbents  

International Nuclear Information System (INIS)

Purpose: To enable to absorb radioactive corrosion products in reactor water even in high temperature and high pressure water, thereby simplify the device and decrease the heat loss. Constitution: Adsorbents comprising from 50 to 70 w/o of Fe or Ni, from 30 to 50 w/o of Ti and from 0 to 5 w/o Li as the ingredient ratio are used in a reactor water clean up facility for removing radioactive corrosion products, particularly, cobalt ions from primary coolant circuits of a nuclear reactor. The use of the adsorbents under higher temperature and pressure than those for ion exchange resins employed so far is enabled by using such a ingredient ratio, by which the degradation in the adsorbing performance and release of once adsorbed impurities are eliminated. Accordingly, a facility for cleaning up the reactor water after once lowered to ambient temperature and normal pressure and then returning into the primary circuits after increasing to higher temperature and pressure is no more required. (Sekiya, K.)

182

Activity of Trypsin Adsorbed on Temperature and pH-Responsive Micron-Sized PS/P(NIPAM-MAA-MBAAm) Composite Polymer Particles  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Micron-sized polystyrene (PS) seed particles were prepared by dispersion polymerization of styrene in ethanol-water media. Seeded copolymerization of N-isopropyl acrylamide (NIPAM), methacrylic acid (MAA) and N,N`-methylene-bis-acrylamide (MBAAm) was then carried out in presence of PS seed particles. The produced PS/P(NIPAM-MAA-MBAAm) composite polymer particles exhibited volume phase transition to small changes in temperature and pH, respectively. Specific activities of trypsin aqueous...

Ashraful Alam, M.; Jalil Miah, M. A.; Hasan Ahmad

2008-01-01

183

Self-assembly of graphene oxide coated soft magnetic carbonyl iron particles and their magnetorheology  

Science.gov (United States)

The surface of carbonyl iron (CI) microspheres was modified with graphene oxide (GO) as a coating material using 4-aminobenzoic acid as the grafting agent. The morphology, elemental composition, and magnetic properties of the GO-coated CI (GO/CI) particles were examined by scanning electron microscopy, energy dispersive X-ray spectroscopy and vibrating sample magnetometry, respectively, confirming their composite formation. The magnetorheological (MR) performance of the GO/CI particle-based suspension was examined using a rotational rheometer connected to a magnetic field supply. The GO/CI particles suspension exhibited typical MR properties with increasing shear stress and viscosity depending on the applied magnetic field strength.

Zhang, W. L.; Choi, H. J.

2014-05-01

184

Self-assembly of graphene oxide coated soft magnetic carbonyl iron particles and their magnetorheology  

Energy Technology Data Exchange (ETDEWEB)

The surface of carbonyl iron (CI) microspheres was modified with graphene oxide (GO) as a coating material using 4-aminobenzoic acid as the grafting agent. The morphology, elemental composition, and magnetic properties of the GO-coated CI (GO/CI) particles were examined by scanning electron microscopy, energy dispersive X-ray spectroscopy and vibrating sample magnetometry, respectively, confirming their composite formation. The magnetorheological (MR) performance of the GO/CI particle-based suspension was examined using a rotational rheometer connected to a magnetic field supply. The GO/CI particles suspension exhibited typical MR properties with increasing shear stress and viscosity depending on the applied magnetic field strength.

Zhang, W. L.; Choi, H. J., E-mail: hjchoi@inha.ac.kr [Department of Polymer Science and Engineering, Inha University, Incheon 402-751 (Korea, Republic of)

2014-05-07

185

Fabrication of ceramic oxide-coated SWNT composites by sol-gel process with a polymer glue  

Energy Technology Data Exchange (ETDEWEB)

The functional copolymer bearing alkoxysilyl and pyrene groups, poly[3-(triethoxysilyl)propyl methacrylate]-co-[(1-pyrene-methyl) methacrylate] (TEPM{sub 13}-co-PyMMA{sub 3}), was synthesized via atom transfer radical polymerization. Attributing the {pi}-{pi} interaction of pyrene units with the walls of single-walled carbon nanotubes (SWNTs), this polymer could disperse and exfoliate SWNTs in different solvents through physical interaction as demonstrated by TEM, UV/Vis absorption, and FT-IR analysis. The alkoxysilyl groups functionalized SWNTs were reacted with different inorganic precursors via sol-gel reaction, and, as a results, silica, titania, and alumina were coated onto the surface of SWNTs, respectively via copolymers as a molecular glue. The nanocomposites of ceramic oxides/SWNTs were characterized by SEM analysis. Dependent upon the feed, the thickness of inorganic coating can be tuned easily. This study supplies a facile and general way to coat SWNTs with ceramic oxides without deteriorating the properties of pristine SWNTs.

Zhang Cheng; Gao Lei; Chen Yongming, E-mail: ymchen@iccas.ac.cn [Institute of Chemistry, Chinese Academy of Sciences, Laboratory of Polymer Physics and Chemistry (China)

2011-09-15

186

Fabrication of ceramic oxide-coated SWNT composites by sol–gel process with a polymer glue  

International Nuclear Information System (INIS)

The functional copolymer bearing alkoxysilyl and pyrene groups, poly[3-(triethoxysilyl)propyl methacrylate]-co-[(1-pyrene-methyl) methacrylate] (TEPM13-co-PyMMA3), was synthesized via atom transfer radical polymerization. Attributing the ?–? interaction of pyrene units with the walls of single-walled carbon nanotubes (SWNTs), this polymer could disperse and exfoliate SWNTs in different solvents through physical interaction as demonstrated by TEM, UV/Vis absorption, and FT-IR analysis. The alkoxysilyl groups functionalized SWNTs were reacted with different inorganic precursors via sol–gel reaction, and, as a results, silica, titania, and alumina were coated onto the surface of SWNTs, respectively via copolymers as a molecular glue. The nanocomposites of ceramic oxides/SWNTs were characterized by SEM analysis. Dependent upon the feed, the thickness of inorganic coating can be tuned easily. This study supplies a facile and general way to coat SWNTs with ceramic oxides without deteriorating the properties of pristine SWNTs.

187

Characteristics of grain growth of microarc oxidation coatings on pure titanium  

Science.gov (United States)

Grainy titania coatings are prepared by microarc oxidation on pure titanium (TA2) substrates in a Na2SiO3-NaF electrolytic solution. The coating thickness is measured by an optical microscope with a CCD camera. Scanning electron microscope (SEM) and x-ray diffraction (XRD) are employed to characterize the microstructure and phase composition of coatings. The results show that the coating thickness increases linearly as the treatment time increases. The coatings are mainly composed of anatase and rutile (TiO2). With the increase of treatment time, the predominant phase composition varies from anatase to rutile, which indicates that phase transformation of anatase into rutile occurs in the oxidizing process. Meanwhile, the size of grains existing on the coating surface increases and thus the surface becomes much coarser.

Wang, Jian-Bo; Wu, Han-Hua; Li, Quan-Jun; Li, Zhe-Kui; Gu, Guang-Rui; Lü, Xian-Yi; Zheng, Wei-Tao; Jin, Zeng-Sun

2005-12-01

188

Plasma electrolytic oxidation coatings on ?TiAl alloy for potential biomedical applications.  

Science.gov (United States)

In an attempt to enhance the potential of gamma titanium aluminide intermetallic alloy as a biomaterial, its surface characteristics were successfully modified using a calcium and phosphorous rich electrolyte through the application of plasma electrolytic oxidation. Scanning electron microscopy and atomic force microscopy were used to characterize the morphology and topographical features of the resulting coating while X-ray diffraction and energy dispersive spectroscopy were used to determine the surface oxide composition. The mechanical properties of the surface coating were characterized by nanoindentation studies. The results observed show the formation of a submicron scale porous structure and a concomitant increase in the surface roughness. The surface oxide was composed of rutile and anatase phases. Composition gradients of Ca and P were also present which can possibly enhance the biomaterial application potential of this treated surface. Nanoindentation measurements indicate the formation of a fairly compact oxide during the process. PMID:24259371

Lara Rodriguez, L; Sundaram, P A; Rosim-Fachini, E; Padovani, A M; Diffoot-Carlo, N

2014-07-01

189

Creation of thin oxide coatings and oxide nanopowders by anodic oxidation of metals in molten salts  

International Nuclear Information System (INIS)

One studied possibility to synthesize highly dispersed oxide powders at anodic oxidation of metals like zirconium and tantalum in chloride nitrate melt (CsCl+NaCl+NaNO3) under temperatures higher than 830 K. It is shown that it is possible to prepare either dense oxide protective coatings on the mentioned metals or oxide powders the particle size of which ranges from 50 up to 100 nm when changing electrolyte composition, oxidation temperature and anode current density

190

Silicon effects on formation of EPO oxide coatings on aluminum alloys  

International Nuclear Information System (INIS)

Electrolytic plasma processes (EPP) can be used for cleaning, metal-coating, carburizing, nitriding, and oxidizing. Electrolytic plasma oxidizing (EPO) is an advanced technique to deposit thick and hard ceramic coatings on a number of aluminum alloys. However, the EPO treatment on Al-Si alloys with a high Si content has rarely been reported. In this research, an investigation was conducted to clarify the effects of silicon contents on the EPO coating formation, morphology, and composition. Cast hypereutectic 390 alloys (? 17% Si) and hypoeutectic 319 alloys (? 7% Si) were chosen as substrates. The coating morphology, composition, and microstructure of the EPO coatings on those substrates were investigated using scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD). A stylus roughness tester was used for surface roughness measurement. It was found that the EPO process had four stages where each stage was corresponding to various coating surface morphology, composition, and phase structures, characterised by different coating growth mechanisms

191

Silicon effects on formation of EPO oxide coatings on aluminum alloys  

Energy Technology Data Exchange (ETDEWEB)

Electrolytic plasma processes (EPP) can be used for cleaning, metal-coating, carburizing, nitriding, and oxidizing. Electrolytic plasma oxidizing (EPO) is an advanced technique to deposit thick and hard ceramic coatings on a number of aluminum alloys. However, the EPO treatment on Al-Si alloys with a high Si content has rarely been reported. In this research, an investigation was conducted to clarify the effects of silicon contents on the EPO coating formation, morphology, and composition. Cast hypereutectic 390 alloys ({approx} 17% Si) and hypoeutectic 319 alloys ({approx} 7% Si) were chosen as substrates. The coating morphology, composition, and microstructure of the EPO coatings on those substrates were investigated using scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD). A stylus roughness tester was used for surface roughness measurement. It was found that the EPO process had four stages where each stage was corresponding to various coating surface morphology, composition, and phase structures, characterised by different coating growth mechanisms.

Wang, L. [Department of Mechanical, Automotive and Materials Engineering, University of Windsor, Windsor, ON, N9B 3P4 (Canada); Nie, X. [Department of Mechanical, Automotive and Materials Engineering, University of Windsor, Windsor, ON, N9B 3P4 (Canada)]. E-mail: xnie@uwindsor.ca

2006-01-03

192

Characterization of calcium containing plasma electrolytic oxidation coatings on AM50 magnesium alloy  

Science.gov (United States)

An attempt was made to produce calcium containing plasma electrolytic oxidation (PEO) coatings on AM50 magnesium alloy using an alkaline electrolyte. This study was performed in three alkaline electrolytes containing calcium hydroxide and sodium phosphate with three different mass ratios viz., 1:2.5, 1:5 and 1:7.5. All the three coatings produced were found to contain Ca and P in appreciable amounts. The concentration of P was found to be higher in the coatings obtained in the electrolytes with higher concentration of phosphate ions. Even though all the three coatings were found to be constituted with magnesium oxide and magnesium phosphate phases, X-ray diffraction analyses revealed that the phase composition was influenced by the phosphate ion concentration/conductivity of the electrolyte. Further, the PEO coating obtained in the 1:7.5 ratio electrolyte was found to contain di-calcium phosphate (monetite) and calcium peroxide phases, which were absent in the other two coatings. Potentiodynamic polarization studies performed in 0.1 M NaCl solution showed that the coatings obtained from the 1:5 ratio electrolyte possessed a superior corrosion resistance, which is attributed to the combined effect of thickness, compactness and phase/chemical composition of this coating.

Srinivasan, P. Bala; Liang, J.; Blawert, C.; Störmer, M.; Dietzel, W.

2010-04-01

193

Characterization of calcium containing plasma electrolytic oxidation coatings on AM50 magnesium alloy  

International Nuclear Information System (INIS)

An attempt was made to produce calcium containing plasma electrolytic oxidation (PEO) coatings on AM50 magnesium alloy using an alkaline electrolyte. This study was performed in three alkaline electrolytes containing calcium hydroxide and sodium phosphate with three different mass ratios viz., 1:2.5, 1:5 and 1:7.5. All the three coatings produced were found to contain Ca and P in appreciable amounts. The concentration of P was found to be higher in the coatings obtained in the electrolytes with higher concentration of phosphate ions. Even though all the three coatings were found to be constituted with magnesium oxide and magnesium phosphate phases, X-ray diffraction analyses revealed that the phase composition was influenced by the phosphate ion concentration/conductivity of the electrolyte. Further, the PEO coating obtained in the 1:7.5 ratio electrolyte was found to contain di-calcium phosphate (monetite) and calcium peroxide phases, which were absent in the other two coatings. Potentiodynamic polarization studies performed in 0.1 M NaCl solution showed that the coatings obtained from the 1:5 ratio electrolyte possessed a superior corrosion resistance, which is attributed to the combined effect of thickness, compactness and phase/chemical composition of this coating.

194

Heterogeneous oligonucleotide-hybridization assay based on hot electron-induced electrochemiluminescence of a rhodamine label at oxide-coated aluminum and silicon electrodes  

Energy Technology Data Exchange (ETDEWEB)

This paper describes a heterogeneous oligonucleotide-hybridization assay based on hot electron-induced electrochemiluminescence (HECL) of a rhodamine label. Thin oxide-film coated aluminum and silicon electrodes were modified with an aminosilane layer and derivatized with short, 15-mer oligonucleotides via diisothiocyanate coupling. Target oligonucleotides were conjugated with tetramethylrhodamine (TAMRA) dye at their amino modified 5' end and hybridization was detected using HECL of TAMRA. Preliminary results indicate sensitivity down to picomolar level and low nonspecific adsorption. The sensitivity was better on oxide-coated silicon compared to oxide-coated aluminum electrodes and two-base pair mismatched hybrids were successfully discriminated. The experimental results presented here might be useful for the design of disposable electrochemiluminescent DNA biosensors.

Spehar-Deleze, Anna-Maria [Laboratory of Sensors, Actuators and Microsystems, Institute of Microtechnology, University of Neuchatel, Rue Jaquet-Droz 1, CH-2007 Neuchatel (Switzerland) and Laboratory of Inorganic and Analytical Chemistry, Helsinki University of Technology, Kemistintie 1, FIN-02015 HUT (Finland)]. E-mail: anna-maria.spehar@unine.ch; Suomi, Johanna [Laboratory of Inorganic and Analytical Chemistry, Helsinki University of Technology, Kemistintie 1, FIN-02015 HUT (Finland); Jiang Qinghong [Laboratory of Inorganic and Analytical Chemistry, Helsinki University of Technology, Kemistintie 1, FIN-02015 HUT (Finland); Rooij, Nico de [Laboratory of Sensors, Actuators and Microsystems, Institute of Microtechnology, University of Neuchatel, Rue Jaquet-Droz 1, CH-2007 Neuchatel (Switzerland); Koudelka-Hep, Milena [Laboratory of Sensors, Actuators and Microsystems, Institute of Microtechnology, University of Neuchatel, Rue Jaquet-Droz 1, CH-2007 Neuchatel (Switzerland); Kulmala, Sakari [Laboratory of Inorganic and Analytical Chemistry, Helsinki University of Technology, Kemistintie 1, FIN-02015 HUT (Finland)

2006-07-28

195

Spectral and optical performance of electrochromic poly(3,4-ethylenedioxythiophene) (PEDOT) deposited on transparent conducting oxide coated glass and polymer substrates  

International Nuclear Information System (INIS)

Electrochromic devices utilizing conjugated polymers as electrochromic layers have gained increasing attention owing to their optical properties, fast switching times and contrast ratios. Polyethylenedioxythiophene (PEDOT) is an excellent material from its electrochromic properties, high conductivity and high stability in the doped form. Aqueous dispersions of PEDOT were either spin coated or electro-polymerized on transparent conducting oxide coated glass and polyethylene tetraphthalate (PET) film substrates. The spectro- and opto-electrochemical studies of the films on transparent conducting oxide coated glass/PET substrates were performed. These films have application in the fabrication of electrochromic windows (smart windows). Smart window devices having excellent switching characteristics over wide range of temperature are used for glazing applications. The aerospace industry is interested in the development of visors and windows that can control glare for pilots and passengers, especially if the coatings can be made on curved surfaces and electrically conducting

196

Retention of nickel from aqueous solutions using iron oxide and manganese oxide coated sand: kinetic and thermodynamic studies.  

Science.gov (United States)

In this study, the removal of nickel ions from aqueous solutions using iron oxide and manganese oxide coated sand (ICS and MCS) under different experimental conditions was investigated. The effect of metal concentration, contact time, solution pH and temperature on the amount of Ni(II) sorbed was studied and discussed. Langmuir and Freundlich isotherm constants and correlation coefficients for the present systems at different temperatures were calculated and compared. The equilibrium process was well described by the Langmuir isotherm model: the maximum sorption capacities (at 29 K) were 2.73 mg Ni/g and 3.33 mg Ni/g of sorbent for ICS and MCS, respectively. Isotherms were also used to evaluate the thermodynamic parameters (deltaG degrees, deltaH degrees, deltaS degrees) of adsorption. The sorption kinetics were tested for the pseudo-first-order, pseudo-second-order and intra-particle diffusion models. Good correlation coefficients were obtained for the pseudo-second-order kinetic model, showing that the nickel uptake process followed the pseudo-second-order rate expression. PMID:21275258

Boujelben, N; Bouzid, J; Elouear, Z; Feki, M

2010-12-14

197

Evaluation of cerium oxide coated Cu cermets as inert anodes for aluminum electrowinning. Final report, August 1990--March 1992  

Energy Technology Data Exchange (ETDEWEB)

Cu/NiFe{sub 2}O{sub 4} cermets were evaluated, with and without an in-situ deposited CEROX (TM; cerium oxide) coating, in 100 h laboratory A1 electrowinning tests. Bath ratio and current density were varied between tests and corrosion was determined by contamination of the aluminum and cryolite by cermet components (Cu, Fe, and Ni). Higher bath ratios of 1.5 to 1.6 led to less corrosion and thicker CEROX coatings. Lower current densities led to slightly less corrosion but much less oxidation of the Cu cermet substrate. At identical test conditions, the corrosion of the CEROX coated cermets was 1/7 that of an uncoated cermet. Corrosion was increased in CEROX coated cermets tested under unsaturated alumina conditions. The electrical conductivity of the CEROX coating was measured to be {approximately}0.2 ohm{sup {minus}1}cm{sup {minus}1}, resulting in a slight voltage penalty, depending on the thickness of the coating.

1992-08-01

198

Adhesive and corrosion-resistant zirconium oxide coatings on stainless steel prepared by ion beam assisted deposition  

International Nuclear Information System (INIS)

To improve the adhesion and corrosion resistance in ceramic and steel systems, zirconium oxide films were deposited on austenitic type 316L stainless-steel substrates by using the ion beam assisted deposition (IBAD) method, in which ZrO2 evaporation and energetic Ar and/or O2 ion bombardment at 250 eV were carried out simultaneously. To study the influence of the film thickness on the performance of coatings, thin (0.2-0.4 ?m) and thick (2-3 ?m) films were prepared. The film structure was investigated by X-ray diffractometry. The adhesion was evaluated by a tensile pull-off tester, showing that IBAD treatments could provide a remarkable potential to enhance the adhesion. The corrosion behavior was determined by potentio-dynamic polarization measurements. It was found that excellent corrosion-protection ability of zirconium oxide coatings on stainless steel was achieved after IBAD treatments. The mechanism for explaining the results has been discussed in terms of the surface observation and X-ray photoelectron spectroscopy studies. (orig.)

199

Removal of iron and arsenic (III) from drinking water using iron oxide-coated sand and limestone  

Science.gov (United States)

A method for removal of iron and arsenic (III) from contaminated water using iron oxide-coated sand and limestone has been developed for drinking water. For the intended use, sand was coated with ferric chloride and used as filtering media. Limestone was added onto the coated sand and the effect of limestone addition on removal efficiency of iron and arsenic was monitored. Both batch and column experiments were conducted to investigate the efficiency of coated sand and limestone as filtering media. Maximum removal of iron (99.8 %) was obtained with coated sand at a dose of 5 g/100 ml and by adding 0.2 g/100 ml of limestone at pH 7.3. Arsenic (III) removal efficiency increased with the increased dose of coated sand and was best removed at pH 7.12. The maximum adsorption capacity for arsenic (III) obtained from Langmuir model was found to be 0.075 mg/g and the kinetics data followed pseudo-first order better than pseudo-second order. Energy dispersive X-ray analysis and FT-IR study proved the removal of iron and arsenic. Column experiment showed removal of iron and arsenic (III) to <0.3 mg/l and 10 ?g/l, respectively, from an initial concentration of 20 mg/l (iron) and 200 ?g/l (arsenic).

Devi, Rashmi R.; Umlong, Iohborlang M.; Das, Bodhaditya; Borah, Kusum; Thakur, Ashim J.; Raul, Prasanta K.; Banerjee, Saumen; Singh, Lokendra

2014-06-01

200

Preparation and properties of plasma electrolytic oxidation coating on sandblasted pure titanium by a combination treatment.  

Science.gov (United States)

Plasma electrolytic oxidation (PEO) is one of the most applicable methods to produce bioceramic coating on a dental implant and sandblasting is a primary technique to modify metal surface properties. This study aims to deposit bioceramic Ca- and P-containing coatings on sandblasted commercially pure titanium by PEO technique to improve its bioactive performance. The time-dependent modified surfaces are characterized in terms of their microstructure, phase, chemical composition, mechanical properties and bioactivities. The results show that the combination-treated coating exhibits better properties than the PEO-treated one, especially in bioactivities, as evidenced by the HA formation after immersion in simulated body fluid (SBF) for 5 days and the cell viability after seeding for 1 or 3 days. The enhancement of the modified surface is attributed to a combination of the mechanical sandblasting and the microplasma oxidation. PMID:25063166

Wang, Hong-Yuan; Zhu, Rui-Fu; Lu, Yu-Peng; Xiao, Gui-Yong; Zhao, Xing-Chuan; He, Kun; Yuan, Y F; Li, Ying; Ma, Xiao-Ni

2014-09-01

 
 
 
 
201

Effects of fluoride on the structure and properties of microarc oxidation coating on aluminium alloy  

Energy Technology Data Exchange (ETDEWEB)

The composition of electrolyte plays a key role in the structure and properties of the synthesized ceramic coating by microarc oxidation (MAO) process. In the present study, F{sup -} ion, the smallest size among the negative ions, is chosen as the additive. The effects of F{sup -} ion on the structure and properties of the formed ceramic coating have been investigated in detail. Inspection of the scanning electron microscopy (SEM) and X-ray diffraction (XRD) suggests that the addition of fluoride during MAO process can decrease the porosity of the surface and enhance the density of the coating. These structure features lead to the corrosion resistances and tribological properties greatly improved. Based on the experimental results and the characteristics of MAO process, the influence mechanism of F{sup -} is proposed.

Wang Zhijiang [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wu Lina [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Cai Wei [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Shan A [Chemical Engineering College, Inner Mongolia University of Technology, Hohhot 010051 (China); Jiang Zhaohua, E-mail: jiangzhaohua@hit.edu.c [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China)

2010-08-27

202

Effects of fluoride on the structure and properties of microarc oxidation coating on aluminium alloy  

International Nuclear Information System (INIS)

The composition of electrolyte plays a key role in the structure and properties of the synthesized ceramic coating by microarc oxidation (MAO) process. In the present study, F- ion, the smallest size among the negative ions, is chosen as the additive. The effects of F- ion on the structure and properties of the formed ceramic coating have been investigated in detail. Inspection of the scanning electron microscopy (SEM) and X-ray diffraction (XRD) suggests that the addition of fluoride during MAO process can decrease the porosity of the surface and enhance the density of the coating. These structure features lead to the corrosion resistances and tribological properties greatly improved. Based on the experimental results and the characteristics of MAO process, the influence mechanism of F- is proposed.

203

High performance Mo adsorbent PZC  

Energy Technology Data Exchange (ETDEWEB)

We have developed Mo adsorbents for natural Mo(n, {gamma}){sup 99}Mo-{sup 99m}Tc generator. Among them, we called the highest performance adsorbent PZC that could adsorb about 250 mg-Mo/g. In this report, we will show the structure, adsorption mechanism of Mo, and the other useful properties of PZC when you carry out the examination of Mo adsorption and elution of {sup 99m}Tc. (author)

Anon.

1998-10-01

204

Positronium chemistry in porous adsorbents  

International Nuclear Information System (INIS)

Kinetic studies on the annihilation of orthopositronium in porous adsorbents have been performed using lifetime spectroscopy. The positron source applied was 22Na with 0.2 MBq activity. The adsorbents investigated were silica gels of different particle size and pore structure. The appearance of the long-lived component in the lifetime spectra can be explained by the diffusion of the orthopositronium into the pores affected by the particle size and the pore size of the adsorbent, the coverage on it and the chemical nature of the adsorbate. The long-term aim of the work is to determine and to explain these effects. (author)

205

Stress-corrosion cracking of indium tin oxide coated polyethylene terephthalate for flexible optoelectronic devices  

International Nuclear Information System (INIS)

Stress corrosion cracking of transparent conductive layers of indium tin oxide (ITO), sputtered on polyethylene terephthalate (PET) substrates, is an issue of paramount importance in flexible optoelectronic devices. These components, when used in flexible device stacks, can be in contact with acid containing pressure-sensitive adhesives or with conductive polymers doped in acids. Acids can corrode the brittle ITO layer, stress can cause cracking and delamination, and stress-corrosion cracking can cause more rapid failure than corrosion alone. The combined effect of an externally-applied mechanical stress to bend the device and the corrosive environment provided by the acid is investigated in this work. We show that acrylic acid which is contained in many pressure-sensitive adhesives can cause corrosion of ITO coatings on PET. We also investigate and report on the combined effect of external mechanical stress and corrosion on ITO-coated PET composite films. Also, it is shown that the combination of stress and corrosion by acrylic acid can cause ITO cracking to occur at stresses less than a quarter of those needed for failure with no corrosion. In addition, the time to failure, under ? 1% tensile strain can reduce the total time to failure by as much as a third

206

Reduced graphene oxide coated optical fiber for methanol and ethanol vapor detection at room temperature  

Science.gov (United States)

Successful isolation of single layer of graphene from graphite by mechanical exfoliation method, attracted a great attention due to its unique structural, optical, mechanical and electronic properties. This makes the graphene as a promising material in many possible applications such as energy-storage, sensing, electronic, optical devices and polymer composite materials. High quality of reduced graphene oxide (rGO) material was prepared by chemical reduction method at 100°C. The structural and optical properties of the rGO sheets were characterized by FT-IR, micro Raman, powder XRD and UV-vis-NIR techniques. FT-IR reveals the absence of oxygen functional groups on rGO due to the reduction process. Powder XRD shows the broad peak at 2?=24.3° corresponding to interlayer spacing 3.66Å which is smaller than the graphene oxide (GO). UV-vis-NIR of rGO displays the absorption peak at 271 nm indicates the reduction of GO and the restoration of C=C bonds in the rGO sheets. The cladding removed and rGO coated poly-methyl methacrylate (PMMA) optical fiber is used for methanol and ethanol vapors detection in the concentration ranging from 0 to 500 ppm at room temperature. The spectral characteristics along with output intensity modulation of cladding removed and rGO coated fiber optic sensor reveal the potential of methanol and ethanol vapor sensing properties.

Kavinkumar, T.; Sastikumar, D.; Manivannan, S.

2014-10-01

207

Formation of microarc oxidation coatings on magnesium alloy with photocatalytic performance  

Science.gov (United States)

Microarc oxidation (MAO) coatings were prepared on AZ91D magnesium alloy in a phosphate electrolyte with and without TiO2 nanoparticles. The effect of TiO2 nanoparticles in the electrolyte on the thickness, surface morphology, composition, structure, corrosion resistance and photocatalytic performance of the coatings were investigated. The appearance and structure of the coatings changed significantly after the TiO2 nanoparticles were added into the electrolyte. The coatings produced in the phosphate electrolyte displayed a grayish white appearance and were mainly composed of MgO and Mg3(PO4)2. However, the coatings formed in the electrolyte with various TiO2 nanoparticles had a blueish color and, additionally, contained the rutile TiO2 and Mg2TiO4. The results of corrosion and photocatalytic measurements show that the coatings formed in the electrolyte with TiO2 nanoparticles not only provided better corrosion protection for magnesium alloy but also exhibited photocatalytic properties.

Li, Weiping; Tang, Mingqi; Zhu, Liqun; Liu, Huicong

2012-10-01

208

Enhanced capacitive performance of TiO2 nanotubes with molybdenum oxide coating  

Science.gov (United States)

Alpha-phase MoO3 is electrochemically deposited on well-aligned TiO2 nanotubes which are synthesized by anodic oxidation. The morphology, composition and electrochemical behaviors of MoO3-coated and bare TiO2 nanotubes are studied. The former deliver greatly higher capacitance than the latter and their performance can be readily optimized by varying MoO3 deposition cycles. The large areal capacitance of 209.6 mF cm-2 at a scan rate of 5 mV s-1 is firstly achieved for TiO2 nanotube array electrode. In addition, the coated TiO2 nanotubes show significantly more capacitance than a dense MoO3 film. For example, they exhibit a capacitance up to 74.9 F g-1 at 5 mV s-1 in 1 M KCl solution, while the dense film only shows a capacitance of 32.3 F g-1 under same conditions. Such improvement is found ascribed to MoO3 with high pseudocapacity and TiO2 nanotubes with large surface area allowing efficient MoO3 nanoparticle loading and rapid charge transfer. This nanostructured electrode with features of facile synthesis and excellent performance is believed as a potential candidate for supercapacitor applications.

Guan, Dongsheng; Gao, Xianfeng; Li, Jianyang; Yuan, Chris

2014-05-01

209

Validation of In-Situ Iron-Manganese Oxide Coated Stream Pebbles as Sensors for Arsenic Source Monitoring  

Science.gov (United States)

Locating nonpoint source contaminant fluxes can be challenging due to the inherent heterogeneity of source and of the subsurface. Contaminants such as arsenic are a concern for drinking water quality and ecosystem health. Arsenic contamination can be the result of several natural and anthropogenic sources, and therefore it can be difficult to trace and identify major areas of arsenic in natural systems. Identifying a useful source indicator for arsenic is a crucial step for environmental remediation efforts. Previous studies have found iron-manganese oxide coated streambed pebbles as useful source indicators due to their high attraction for heavy metals in water. In this study, pebbles, surface water at baseflow and nearby rocks were sampled from the Pennypack Creek and its tributaries, in southwestern Pennsylvania, to test the ability of coated streambed pebbles as environmental source indicators for arsenic. Quartz pebbles, 5-7 cm in diameter, were sampled to minimize elemental contamination from rock chemistry. In addition, quartz provides an excellent substrate for iron and manganese coatings to form. These coatings were leached from pebbles using 4M nitric acid with 0.1% concentrated hydrochloric acid. Following sample processing, analyses were performed using an ICP-MS and the resulting data were spatially organized using ArcGIS software. Arsenic, iron and manganese concentrations in the leachate are normalized to pebble surface area and each location is reported as a ratio of arsenic to iron and manganese. Results suggest that iron-manganese coated stream pebbles are useful indicators of arsenic location within a watershed.

Blake, J.; Peters, S. C.; Casteel, A.

2013-12-01

210

Growth and characterization of chromium oxide coatings prepared by pulsed-direct current reactive unbalanced magnetron sputtering  

International Nuclear Information System (INIS)

Approximately 0.2-3.2 ?m thick single phase chromium oxide (Cr2O3) coatings with different oxygen flow rates were deposited on silicon and mild steel substrates at low substrate temperature (?60 deg. C) by pulsed-direct current (DC) reactive unbalanced magnetron sputtering. Two asymmetric bipolar-pulsed DC generators were used to co-sputter two Cr targets, in Ar + O2 plasma. The coatings were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nanoindentation hardness tester, optical microscopy, atomic force microscopy, micro-Raman spectroscopy, spectroscopic ellipsometry and potentiodynamic polarization techniques. The XRD data showed the presence of mixture of crystalline (rhombohedral Cr2O3) and amorphous phases for the coatings prepared with oxygen flow rate less than 10 sccm. A complete transformation to amorphous phase was observed at higher oxygen flow rates. The XRD results were supported by Raman spectroscopy data. The XPS data suggested that the chemical state of Cr was in the form of Cr3+. The chromium oxide coatings exhibited a maximum hardness of 22 GPa and an elastic modulus of 208 GPa. The coatings exhibited high thermal stability upon annealing in vacuum up to 500 deg. C and retained hardness as high as 17 GPa. Spectroscopic ellipsometry data indicated that coatings prepared at higher oxygen flow rates were dielectric in nature and those prepared at lotric in nature and those prepared at low oxygen flow rates exhibited an intermediate character, i.e., a transition between the dielectric and the metallic behavior. The corrosion behavior of Cr2O3 coating deposited on mild steel substrates was investigated using potentiodynamic polarization in 3.5% NaCl solution. The results indicated that Cr2O3 coating exhibited superior corrosion resistance as compared to the uncoated substrate

211

Magnetic heating properties and neutron activation of tungsten-oxide coated biocompatible FePt core-shell nanoparticles.  

Science.gov (United States)

Magnetic nanoparticles are highly desirable for biomedical research and treatment of cancer especially when combined with hyperthermia. The efficacy of nanoparticle-based therapies could be improved by generating radioactive nanoparticles with a convenient decay time and which simultaneously have the capability to be used for locally confined heating. The core-shell morphology of such novel nanoparticles presented in this work involves a polysilico-tungstate molecule of the polyoxometalate family as a precursor coating material, which transforms into an amorphous tungsten oxide coating upon annealing of the FePt core-shell nanoparticles. The content of tungsten atoms in the nanoparticle shell is neutron activated using cold neutrons at the Heinz Maier-Leibnitz (FRMII) neutron facility and thereby transformed into the radioisotope W-187. The sizeable natural abundance of 28% for the W-186 precursor isotope, a radiopharmaceutically advantageous gamma-beta ratio of ???30% and a range of approximately 1mm in biological tissue for the 1.3MeV ?-radiation are promising features of the nanoparticles' potential for cancer therapy. Moreover, a high temperature annealing treatment enhances the magnetic moment of nanoparticles in such a way that a magnetic heating effect of several degrees Celsius in liquid suspension - a prerequisite for hyperthermia treatment of cancer - was observed. A rise in temperature of approximately 3°C in aqueous suspension is shown for a moderate nanoparticle concentration of 0.5mg/ml after 15min in an 831kHz high-frequency alternating magnetic field of 250Gauss field strength (25mT). The biocompatibility based on a low cytotoxicity in the non-neutron-activated state in combination with the hydrophilic nature of the tungsten oxide shell makes the coated magnetic FePt nanoparticles ideal candidates for advanced radiopharmaceutical applications. PMID:25445697

Seemann, K M; Luysberg, M; Révay, Z; Kudejova, P; Sanz, B; Cassinelli, N; Loidl, A; Ilicic, K; Multhoff, G; Schmid, T E

2015-01-10

212

Treatment of heavy metals by iron oxide coated and natural gravel media in Sustainable urban Drainage Systems.  

Science.gov (United States)

Sustainable urban Drainage Systems (SuDS) filter drains are simple, low-cost systems utilized as a first defence to treat road runoff by employing biogeochemical processes to reduce pollutants. However, the mechanisms involved in pollution attenuation are poorly understood. This work aims to develop a better understanding of these mechanisms to facilitate improved SuDS design. Since heavy metals are a large fraction of pollution in road runoff, this study aimed to enhance heavy metal removal of filter drain gravel with an iron oxide mineral amendment to increase surface area for heavy metal scavenging. Experiments showed that amendment-coated and uncoated (control) gravel removed similar quantities of heavy metals. Moreover, when normalized to surface area, iron oxide coated gravels (IOCGs) showed poorer metal removal capacities than uncoated gravel. Inspection of the uncoated microgabbro gravel indicated that clay particulates on the surface (a natural product of weathering of this material) augmented heavy metal removal, generating metal sequestration capacities that were competitive compared with IOCGs. Furthermore, when the weathered surface was scrubbed and removed, metal removal capacities were reduced by 20%. When compared with other lithologies, adsorption of heavy metals by microgabbro was 10-70% higher, indicating that both the lithology of the gravel, and the presence of a weathered surface, considerably influence its ability to immobilize heavy metals. These results contradict previous assumptions which suggest that gravel lithology is not a significant factor in SuDS design. Based upon these results, weathered microgabbro is suggested to be an ideal lithology for use in SuDS. PMID:23925197

Norris, M J; Pulford, I D; Haynes, H; Dorea, C C; Phoenix, V R

2013-01-01

213

Development of molecular adsorber coatings  

Science.gov (United States)

As mission, satellite, and instrument performance requirements become more advanced, the need to control adverse onorbit molecular contamination is more critical. Outgassed materials within the spacecraft have the potential to degrade performance of optical surfaces, thermal control surfaces, solar arrays, electronics, and detectors. One method for addressing the outgassing of materials is the use of molecular adsorbers. On Goddard Space Flight Center missions such as Hubble Space Telescope (HST), Tropical Rainfall Measuring Mission (TRMM), and SWIFT, Zeolite-coated cordierite molecular adsorbers were successfully used to collect and retain outgassed molecular effluent emanating from spacecraft materials, protecting critical contamination sensitive surfaces. However, the major drawbacks of these puck type adsorbers are weight, size, and mounting hardware requirements, making them difficult to incorporate into spacecraft designs. To address these concerns, a novel molecular adsorber coating was developed to alleviate the size and weight issues while providing a configuration that more projects can utilize, particularly contamination sensitive instruments. This successful sprayable molecular adsorber coating system demonstrated five times the adsorption capacity of previously developed adsorber coating slurries. The molecular adsorber formulation was refined and a procedure for spray application was developed. Samples were spray coated and tested for capacity, thermal optical/radiative properties, coating adhesion, and thermal cycling. The tested formulation passes coating adhesion and vacuum thermal cycling tests between +140 and -115C. Thermal radiative properties are very promising. Work performed during this study indicates that the molecular adsorber formulation can be applied to aluminum, stainless steel, or other metal substrates that can accept silicate coatings.

Straka, Sharon; Peters, Wanda; Hasegawa, Mark; Novo-Gradac, Kevin; Wong, Alfred

2010-08-01

214

Influence of C 3H 8O 3 in the electrolyte on characteristics and corrosion resistance of the microarc oxidation coatings formed on AZ91D magnesium alloy surface  

Science.gov (United States)

Ceramic coatings were fabricated on AZ91D Mg-alloy substrate by microarc oxidation in Na 2SiO 3-NaOH-Na 2EDTA electrolytes with and without C 3H 8O 3 addition. The effects of different concentrations of C 3H 8O 3 contained in the electrolyte on coatings thickness were investigated. The surface morphologies, RMS roughness, phase compositions and corrosion resistance property of the ceramic coatings were analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and electrochemical corrosion test respectively. It is found that the addition of C 3H 8O 3 into silicate electrolyte leads to increase of the unit-area adsorptive capacity of the negative ions at anode-electrolyte interface and thus improves the compactness and corrosion resistance of the MAO coating. The coating thickness decreases gradually with the increase of concentrations of C 3H 8O 3 in the electrolyte. The oxide coating formed in base electrolyte containing 4 mL/L C 3H 8O 3 exhibits the best surface appearance, the lowest surface RMS roughness (174 nm) and highest corrosion resistance. In addition, both ceramic coatings treated in base electrolyte with and without C 3H 8O 3 are mainly composed of periclase MgO and forsterite Mg 2SiO 4 phase, but no diffraction peak of Mg phase is found in the patterns.

Wu, Di; Liu, Xiangdong; Lu, Kai; Zhang, Yaping; Wang, Huan

2009-05-01

215

Influence of C3H8O3 in the electrolyte on characteristics and corrosion resistance of the microarc oxidation coatings formed on AZ91D magnesium alloy surface  

International Nuclear Information System (INIS)

Ceramic coatings were fabricated on AZ91D Mg-alloy substrate by microarc oxidation in Na2SiO3-NaOH-Na2EDTA electrolytes with and without C3H8O3 addition. The effects of different concentrations of C3H8O3 contained in the electrolyte on coatings thickness were investigated. The surface morphologies, RMS roughness, phase compositions and corrosion resistance property of the ceramic coatings were analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and electrochemical corrosion test respectively. It is found that the addition of C3H8O3 into silicate electrolyte leads to increase of the unit-area adsorptive capacity of the negative ions at anode-electrolyte interface and thus improves the compactness and corrosion resistance of the MAO coating. The coating thickness decreases gradually with the increase of concentrations of C3H8O3 in the electrolyte. The oxide coating formed in base electrolyte containing 4 mL/L C3H8O3 exhibits the best surface appearance, the lowest surface RMS roughness (174 nm) and highest corrosion resistance. In addition, both ceramic coatings treated in base electrolyte with and without C3H8O3 are mainly composed of periclase MgO and forsterite Mg2SiO42SiO4 phase, but no diffraction peak of Mg phase is found in the patterns.

216

Polyacrylate adsorbents for the selective adsorption of cholesterol-rich lipoproteins from plasma or blood  

Directory of Open Access Journals (Sweden)

Full Text Available Polyacrylate (PAA adsorbents selectively bind low density lipoproteins (LDL from human plasma and blood, whereas very low density lipoproteins (VLDL are only minimally adsorbed. The adsorption of cholesterol-rich lipoproteins to PAA adsorbents is related to the molecular weight (mw of the polyanion ligand. Ca++ and Mg++ inhibit the binding of LDL to PAA adsorbents. The chemical composition of the organic hardgels of the adsorbents does not have an influence on adsorption. The selective adsorption of LDL to PAA adsorbents can be explained to result from their low negative surface charge density and the specific colloid-chemical properties of the surface-bound PAA, which do not prevent LDL from binding to charge-like domains of the ligand. By contrast, VLDL and high density lipoproteins (HDL are repelled from the adsorbents due to their higher negative surface charge density.

Heuck, Claus-Chr.

2011-01-01

217

Instability of waste plumes adsorbed on iron oxide in soils  

International Nuclear Information System (INIS)

Iron (hydrous) oxide coatings on the solid matrix dominate adsorption in many soils. Their adsorption characteristics vary considerably with the composition of the soil pore water. If the latter is not sufficiently buffered, the contaminant distribution between solid and soluble soil phases, Kd (''distribution coefficient''), will change as intruding water differing in chemical composition from the original one in the system progresses through the plume environment. Thus, the Kd's at different locations within the plume become time dependent, spatially variable and causally correlated. The conventional constant or stochastic Kd model is not capable of describing contaminant migration in such a situation. A geochemical equilibrium model, the so-called triple layer model, has been incorporated into a transport code and is used to calculate the adsorption processes and, thus, the Kd as a function of environmental parameters. The major processes occurring are: (a) accumulation of a proton reservoir on the surface itself, (2) development of a charge cloud at a distance of several angstroms from the surface, capable of accommodating contaminant ions, and (3) development of a net charge at the oxide/water interface and, consequently, the creation of a cation or anion exchange capacity of the oxide

218

Instability of waste plumes adsorbed on iron oxide in soils  

International Nuclear Information System (INIS)

Iron (hydrous) oxide coatings on the solid matrix dominate adsorption in many soils. Their adsorption characteristics vary considerably with the composition of the soil pore water. If the latter is not sufficiently buffered, the contaminant distribution between solid and soluble soil phase, Kd (''distribution coefficient''), will change as intruding water differing in chemical composition from the original one in the system progresses through the plume environment. Thus the Kd's at different locations within the plume become time dependent, spatially variable and causally correlated. The conventional constant or stochastic Kd model is not capable of describing contaminant migration in such a situation. A geochemical equilibrium model, the so-called triple layer model, has been incorporated into a transport code and is used to calculate the adsorption processes and thus the Kd as a function of environmental parameters. The major processes occurring are: (1) accumulation of a proton reservoir on the surface itself; (2) development of a charge cloud at a distance of several angstroms from the surface, capable of accommodating contaminant ions; and (3) development of a net charge at the oxide/water interface and, consequently, the creation of a cation or anion exchange capacity of the oxide

219

Composites  

International Nuclear Information System (INIS)

This chapter discusses the roles of composite laminates and aggregates in cryogenic technology. Filamentary-reinforced composites are emphasized because they are the most widely used composite materials. Topics considered include composite systems and terminology, design and fabrication, composite failure, high-pressure reinforced plastic laminates, low-pressure reinforced plastics, reinforced metals, selectively reinforced structures, the effect of cryogenic temperatures, woven-fabric and random-mat composites, uniaxial fiber-reinforced composites, composite joints in cryogenic structures, joining techniques at room temperature, radiation effects, testing laminates at cryogenic temperatures, static and cyclic tensile testing, static and cyclic compression testing, interlaminar shear testing, secondary property tests, and concrete aggregates. It is suggested that cryogenic composite technology would benefit from the development of a fracture mechanics model for predicting the fitness-for-purpose of polymer-matrix composite structures

220

Diatomaceous earth containing adsorbent, method for making, and methods of use thereof  

International Nuclear Information System (INIS)

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)

 
 
 
 
221

Krypton retention on solid adsorbents  

International Nuclear Information System (INIS)

An experimental laboratory program was conducted to develop economical solid adsorbents for the retention of krypton from a dissolver off-gas stream. The study indicates that a solid adsorbent system is feasible and competitive with other developing systems which utilize fluorocarbon absorption nd cryogenic distillation. This technology may have potential applications not only in nuclear fuel reprocessing plants, but also in nuclear reactors and in environmental monitoring. Of the 13 prospective adsorbents evaluated with respect to adsorption capacity and cost, the commercially available hydrogen mordenite was the most cost-effective material at subambient temperatures (-400 to -800C). Silver mordenite has a higher capacity for krypton retention, but is 50 times more expensive than hydrogen mordenite

222

Influence of C{sub 3}H{sub 8}O{sub 3} in the electrolyte on characteristics and corrosion resistance of the microarc oxidation coatings formed on AZ91D magnesium alloy surface  

Energy Technology Data Exchange (ETDEWEB)

Ceramic coatings were fabricated on AZ91D Mg-alloy substrate by microarc oxidation in Na{sub 2}SiO{sub 3}-NaOH-Na{sub 2}EDTA electrolytes with and without C{sub 3}H{sub 8}O{sub 3} addition. The effects of different concentrations of C{sub 3}H{sub 8}O{sub 3} contained in the electrolyte on coatings thickness were investigated. The surface morphologies, RMS roughness, phase compositions and corrosion resistance property of the ceramic coatings were analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and electrochemical corrosion test respectively. It is found that the addition of C{sub 3}H{sub 8}O{sub 3} into silicate electrolyte leads to increase of the unit-area adsorptive capacity of the negative ions at anode-electrolyte interface and thus improves the compactness and corrosion resistance of the MAO coating. The coating thickness decreases gradually with the increase of concentrations of C{sub 3}H{sub 8}O{sub 3} in the electrolyte. The oxide coating formed in base electrolyte containing 4 mL/L C{sub 3}H{sub 8}O{sub 3} exhibits the best surface appearance, the lowest surface RMS roughness (174 nm) and highest corrosion resistance. In addition, both ceramic coatings treated in base electrolyte with and without C{sub 3}H{sub 8}O{sub 3} are mainly composed of periclase MgO and forsterite Mg{sub 2}SiO{sub 4} phase, but no diffraction peak of Mg phase is found in the patterns.

Wu Di, E-mail: wudiyhj0808@yahoo.cn [School of Materials Science and Engineering, Inner Mongolia University of Technology, 49 Aimin Street, Hohhot 010051 (China); Liu Xiangdong; Lu Kai; Zhang Yaping; Wang Huan [School of Materials Science and Engineering, Inner Mongolia University of Technology, 49 Aimin Street, Hohhot 010051 (China)

2009-05-30

223

[Nisin adsorption on silica adsorbents].  

Science.gov (United States)

It has been shown that silica adsorbents can be used for adsorption of nizin from solutions obtained after centrifugation of the fermentation broth. The optimal structure of the adsorbent pores has been determined. Silica with pores 50 to 75 nm in size provided the highest adsorption rates. The value of silica adsorption of nizin depended on the medium pH. The maximum adsorption rates were observed at pH 6.5--7. At pH 3.5 the level of nizin adsorption was low. PMID:6305260

Baranova, I P; Grushina, V A; Nikitin, Iu S; Egorov, N S; Polin, A N

1983-04-01

224

Browns Ferry charcoal adsorber incident  

International Nuclear Information System (INIS)

The article reviews the temperature excursion in the charcoal adsorber beds of the Browns Ferry Unit 3 off-gas system that occurred on July 17, 1977. Significant temperature increases were experienced in the charcoal adsorber beds when charcoal fines were ignited by the ignition of a combustible mixture of hydrogen and oxygen in the off-gas system. The Browns Ferry off-gas system is described, and events leading up to and surrounding the incident are discussed. The follow-up investigation by Tennessee Valley Authority and General Electric Company personnel and their recommendations for system and operational modifications are summarized

225

Method of processing spent adsorbents  

International Nuclear Information System (INIS)

Purpose: To make spent adsorbents combustible and prevent the dispersion of adsorbed substance upon combustion. Method: Organic compounds such as saccharides are adsorbed saturately on activated carbon or ion exchange resins. Further, saccharides are additionally incorporated, kneaded and dried into a block form. Then, they are burnt. For instance, after adding an aqueous 1% solution of sucrose by 0.5 liter per 1 kg of the activated carbon and uniformly kneading, they are dried at 1200C for about one hour. Subsequently, 0.5 liter of an aqueous 10% solution of sucrose are added, uniformly kneaded and dried at 1200C for about one hour into a block form. Upon igniting with burner, they can be combusted spontaneously with no flames to leave only metal-oxide cinders. The saccharides can be replaced with starches or gum arabic. If the concentration of the saccharides to be added is high, although the combustion velocity is increased, the risk of dispersing adsorbed substances may be resulted. (Ikeda, J.)

226

SUPERCRITICAL FLUID REGENERATION OF ADSORBENTS  

Science.gov (United States)

The report gives results of a program: (1) to perform studies supercritical (fluid) carbon dioxide (SCF CO2) regeneration of adsorbents, using samples of industrial wastewaters from manufacturing pesticides and synthetic solutions; and (2) to estimate the economics of the specifi...

227

Composites  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This thesis was a literature study concerning composites. With composites becoming increasingly popular in various areas such as aerospace industry and construction, the research about composites has a significant meaning accordingly. This thesis was aim at introducing some basic information of polymer matrix composites including raw mate-rial, processing, testing, applications and recycling to make a rough understanding of this kind of material for readers. Polymeric matrices, fillers,...

Zhao, Hanqing; Guo, Yuanzheng

2014-01-01

228

Water vapor adsorption characteristics of honeycomb adsorbents  

International Nuclear Information System (INIS)

For large volume air clean-up in nuclear fusion facilities, honeycomb-type adsorbents offer a useful advantage in terms of their low-pressure drop. In this study, two different honeycomb-type adsorbents (honeycomb-K and honeycomb-N) and pebble-type adsorbents were used as samples and the water vapor adsorption performance of each adsorbent was examined by changing temperature, concentration of water vapor and flow rate. The honeycomb-K and honeycomb-N adsorbents included zeolite-4A or zeolite-5A with a 50% clay binder and with a 15% sepiolite binder, respectively. The shapes of cells in honeycomb-K and honeycomb-N are triangles with 1 mm sides and squares with 1 mm sides, respectively, and the cell densities of the both adsorbents were 200 CPSI (cells/in.2). The adsorption capacity for water vapor on the honeycomb-K adsorbent was comparable to that on the pebble-type adsorbent, while the adsorption capacity on the honeycomb-N adsorbent was lower. The adsorption rates of honeycomb-K and honeycomb-N adsorbents were higher than that of the pebble-type adsorbent. The honeycomb-K adsorbent containing zeolite-5A showed a higher adsorption rate than that containing zeolite-4A. Thus, honeycomb-K containing zeolite-5A adsorbent could be applicable to air cleanup systems in terms of both adsorption capacity and rate.

229

Comparison of Theoretically and Experimentally Determined Effects of Oxide Coatings Supplied by Fuel Additives on Uncooled Turbine-blade Temperature During Transient Turbojet-engine Operation  

Science.gov (United States)

An analysis was made to permit the calculation of the effectiveness of oxide coatings in retarding the transient heat flow into turbine blades when the combustion gas temperature of a turbojet engine is suddenly changed. The analysis is checked with experimental data obtained from a turbojet engine whose blades were coated with two different coating materials (silicon dioxide and boric oxide) by adding silicone oil and tributyl borate to the engine fuel. The very thin coatings (approximately 0.001 in.) that formed on the blades produced a negligible effect on the turbine-blade transient temperature response. With the analysis discussed here, it was possible to predict the turbine rotor-blade temperature response with a maximum error of 40 F.

Schafer, Louis J; Stepka, Francis S; Brown, W Byron

1953-01-01

230

Application of vapor phase decomposition techniques (VPD/AAS and ICP-MS) for trace element analysis in oxide coatings on silicon  

International Nuclear Information System (INIS)

The use of VPD/AAS and ICP-MS techniques to measure metallic contamination in a silicon oxide film is described. Metallic contamination such as Na, Al, Ca, Cr, Fe, Cu and Zn which may be introduced during cleaning, etching oxide growth and ion implantation processes is demonstrated to be reliably and accurately monitored by this technique. In VPD techniques, an oxide film is decomposed by hydrofluoric acid vapor and all the metals on the silicon wafer surface are dissolved into a small volume of liquid. The liquid is then transferred to an AAS equipped with a graphite furnace or an ICP-MS for metal analysis. Since the entire oxide film is dissolved for analysis, VPD technique measures the average concentration of a metal in an oxide coating. Surface metal concentration as low as 109-1010 atoms/cm2 may be detected by these techniques. (orig.)

231

Modification of optical and electrical properties of zinc oxide-coated porous silicon nanostructures induced by swift heavy ion  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Morphological and optical characteristics of radio frequency-sputtered zinc aluminum oxide over porous silicon (PS) substrates were studied before and after irradiating composite films with 130?MeV of nickel ions at different fluences varying from 1?×?1012 to 3?×?1013 ions/cm2. The effect of irradiation on the composite structure was investigated by scanning electron microscopy, X-ray diffraction (XRD), photoluminescence (PL), and cathodoluminescence spectroscopy. Current–voltag...

Kumar, Yogesh; Herrera-zaldivar, Manuel; Olive-me?ndez, Sion Federico; Singh, Fouran; Mathew, Xavier; Agarwal, Vivechana

2012-01-01

232

Effects of adsorbates on submonolayer growth  

CERN Document Server

The effects of adsorbates on nucleation and growth of two-dimensional islands is investigated by kinetic Monte Carlo simulations and rate equation theory. The variation of island morphology with adsorbate parameters is discussed and the temperature-dependence of island density in the case of immobile adsorbates is studied in detail. A set of rate equations for the description of nucleation in the presence of predeposited mobile and immobile adsorbates is developed.

Kotrla, M; Smilauer, P; Kotrla, Miroslav; Krug, Joachim; Smilauer, Pavel

2001-01-01

233

Development of new molybdenum adsorbent  

International Nuclear Information System (INIS)

Neutron Irradiation and Testing Reactor Center has developed for production of medical isotope of 99Mo, the parent nuclide of 99mTc by the (n, ?) method use JMTR. The (n, ?) method has an advantage of easy manufacturing process and low radioactive wastes generation. However, the low radioactivity concentration of 99mTc is remaining as an issue. Therefore, PZC was developed as adsorbent of molybdenum. However, PZC has some faults. So, new adsorbent based on titanium (PTC), was developed for getting rid of faults. This time, 99Mo adsorption and 99mTc elution tests with PZC and PTC were carried out. As a result, the 99Mo adsorption performance of the PTC was lower than PZC, on the other hand, 99mTc elution performance of the PTC was higher than PZC. (author)

234

Method And Apparatus For Regenerating Nox Adsorbers  

Energy Technology Data Exchange (ETDEWEB)

Methods and apparatuses for regenerating a NOx adsorber coupled with an exhaust of an engine. An actuator drives a throttle valve to a first position when regeneration of the NOx adsorber is desired. The first position is a position that causes the regeneration of the NOx adsorber. An actuator drives the throttle valve to a second position while regeneration of the NOx adsorber is still desired. The second position being a position that is more open than the first position and operable to regenerate a NOx adsorber.

Driscoll, J. Joshua (Dunlap, IL); Endicott, Dennis L. (Peoria, IL); Faulkner, Stephen A. (Stamford, GB); Verkiel, Maarten (Metamora, IL)

2006-03-28

235

Preparations of PAN-based adsorbers for separation of cesium and cobalt from radioactive wastes  

International Nuclear Information System (INIS)

Ion-exchange adsorbers are widely used for radioisotope separation, as well as for the removal of hazardous fission products from aqueous waste prior to discharge to the environment. Inorganic exchangers are of particular interest because of their resistance to radiolytic damage and selectivity for specific fission products. Composite inorganic-organic adsorbers represent a group of inorganic ion exchangers modified by using binding organic material, polyacrylonitrile, for preparation of larger size particles with higher granular strength. At the same time, kinetics of ion exchange and sorption capacity of such composite adsorbers are not influenced by the binding polymer. The contents of active component in composite adsorber were varied over a very broad range of 5-95% of the dry weight of the composite adsorber, and tested for separation and concentration of various stimulated wastes. Three different inorganic sorbents, granular hexacyanoferrate-based ion exchanger, were developed for the removal of Cs and Co ions from waste solutions containing different complexing agents as detergents. Radiation and thermal stability studies show that these adsorbents can be used for medium-active waste treatment

236

Preparations of PAN-based adsorbers for separation of cesium and cobalt from radioactive wastes  

Energy Technology Data Exchange (ETDEWEB)

Ion-exchange adsorbers are widely used for radioisotope separation, as well as for the removal of hazardous fission products from aqueous waste prior to discharge to the environment. Inorganic exchangers are of particular interest because of their resistance to radiolytic damage and selectivity for specific fission products. Composite inorganic-organic adsorbers represent a group of inorganic ion exchangers modified by using binding organic material, polyacrylonitrile, for preparation of larger size particles with higher granular strength. At the same time, kinetics of ion exchange and sorption capacity of such composite adsorbers are not influenced by the binding polymer. The contents of active component in composite adsorber were varied over a very broad range of 5-95% of the dry weight of the composite adsorber, and tested for separation and concentration of various stimulated wastes. Three different inorganic sorbents, granular hexacyanoferrate-based ion exchanger, were developed for the removal of Cs and Co ions from waste solutions containing different complexing agents as detergents. Radiation and thermal stability studies show that these adsorbents can be used for medium-active waste treatment.

Nilchi, A. [Jaber Ibn Hayan Research Laboratories, Atomic Energy Organization of Iran, P.O. Box 11365/8486, Tehran (Iran, Islamic Republic of)]. E-mail: anilchi@aeoi.org.ir; Atashi, H. [Sistan and Baluchestan University, Zahedan (Iran, Islamic Republic of); Javid, A.H. [Azad University, Tehran (Iran, Islamic Republic of); Saberi, R. [Jaber Ibn Hayan Research Laboratories, Atomic Energy Organization of Iran, P.O. Box 11365/8486, Tehran (Iran, Islamic Republic of)

2007-05-15

237

Enhanced encapsulation of metoprolol tartrate with carbon nanotubes as adsorbent  

Science.gov (United States)

A highly water-soluble antihypertensive drug, metoprolol tartrate (MT), was selected as a model drug for preparation of multi-walled carbon nanotubes (MWCNTs)-impregnated ethyl cellulose (EC) microspheres. The present investigation was aimed to increase encapsulation efficiency of MT with excellent adsorbent properties of MWCNTs. The unique surface area, stiffness, strength and resilience of MWCNTs have drawn much anticipation as carrier for highly water-soluble drugs. Carbon nanotubes drug adsorbate (MWCNTs:MT)-loaded EC microspheres were further optimized by the central composite design of the experiment. The effects of independent variables (MWCNTs:MT and EC:adsorbate) were evaluated on responses like entrapment efficiency (EE) and t 50 (time required for 50% drug release). The optimized batch was compared with drug alone EC microspheres. The results revealed high degree of improvement in encapsulation efficiency for MWCNTs:MT-loaded EC microspheres. In vitro drug release study exhibited complete release form drug alone microspheres within 15 h, while by the same time only 50-60% drug was released for MWCNTs-impregnated EC microspheres. The optimized batch was further characterized by various instrumental analyses such as scanning electron microscopy, powder X-ray diffraction and differential scanning calorimetry. The results endorse encapsulation of MWCNTs:MT adsorbate inside the matrix of EC microspheres, which might have resulted in enhanced encapsulation and sustained effect of MT. Hence, MWCNTs can be utilized as novel carriers for extended drug release and enhanced encapsulation of highly water-soluble drug, MT.

Garala, Kevin; Patel, Jaydeep; Patel, Anjali; Dharamsi, Abhay

2011-12-01

238

Removal of radioactive iodine from water using Ag2O grafted titanate nanolamina as efficient adsorbent  

International Nuclear Information System (INIS)

Highlights: ? Ag2O nanocrystals were deposited on titanate nanolamina prepared from TiOSO4. ? The composite is efficient adsorbent for removal of radioactive Iodine from water. ? The adsorbent exhibited a high capacity of 3.4 mmol of iodine per gram of adsorbent in 1 h. ? Ag2O nanocrystals are firmly anchored on the surface of the titanate lamina by coherent interface. ? The adsorbent can be recovered easily for safe disposal and suitable for column adsorption-bed. -- Abstract: Emergency treatment of radioactive material leakage and safety disposal of nuclear waste is a constant concern all along with the development of radioactive materials applications. To provide a solution, titanate with large surface area (143 m2 g?1) and a lamina morphology (the thickness of the lamina is in range of tens of nanometers) was prepared from inorganic titanium compounds by hydrothermal reactions at 433 K. Ag2O nanocrystals (5–30 nm) were deposited onto the titanate lamina. The surface of the titanate lamina has crystallographic similarity to that of Ag2O nanocrystals. Hence, the deposited Ag2O nanocrystals and titanate substrate join together at these surfaces, forming a well-matched phase coherent interface between them. Such coherence between the two phases reduces the overall energy by minimizing surface energy and anchors the Ag2O nanocrystals firmly on the external surface of the titanate structure. The composite thus obtained was applied as efficient adsorbent to remove radioactive iodine from water (one gram adsorbent can capture up to 3.4 mmol of I? anions). The composite adsorbent can be recovered easily for safe disposal. The structure changes of the titanate lamina and the composite adsorbent were monitored by various techniques. The isotherm and kinetics of iodine adsorption, competitive adsorption and column adsorption using the adsorbent were studied to assess its iodine removal abilities. The adsorbent exhibited a capacity as high as 3.4 mmol of iodine per gram of adsorbent in 1 h. Therefore, Ag2O deposited titanate lamina is an effective adsorbent for removing radioactive iodine from water

239

Amorphous vanadium oxide coating on graphene by atomic layer deposition for stable high energy lithium ion anodes.  

Science.gov (United States)

Uniform amorphous vanadium oxide films were coated on graphene via atomic layer deposition and the nano-composite displays an exceptional capacity of ~900 mA h g(-1) at 200 mAg(-1) with an excellent capacity retention at 1 A g(-1) after 200 cycles. The capacity contribution (1161 mA h g(-1)) from vanadium oxide only almost reaches its theoretical value. PMID:25079002

Sun, Xiang; Zhou, Changgong; Xie, Ming; Hu, Tao; Sun, Hongtao; Xin, Guoqing; Wang, Gongkai; George, Steven M; Lian, Jie

2014-09-21

240

Modification of optical and electrical properties of zinc oxide-coated porous silicon nanostructures induced by swift heavy ion.  

Science.gov (United States)

Morphological and optical characteristics of radio frequency-sputtered zinc aluminum oxide over porous silicon (PS) substrates were studied before and after irradiating composite films with 130?MeV of nickel ions at different fluences varying from 1?×?1012 to 3?×?1013 ions/cm2. The effect of irradiation on the composite structure was investigated by scanning electron microscopy, X-ray diffraction (XRD), photoluminescence (PL), and cathodoluminescence spectroscopy. Current-voltage characteristics of ZnO-PS heterojunctions were also measured. As compared to the granular crystallites of zinc oxide layer, Al-doped zinc oxide (ZnO) layer showed a flaky structure. The PL spectrum of the pristine composite structure consists of the emission from the ZnO layer as well as the near-infrared emission from the PS substrate. Due to an increase in the number of deep-level defects, possibly oxygen vacancies after swift ion irradiation, PS-Al-doped ZnO nanocomposites formed with high-porosity PS are shown to demonstrate a broadening in the PL emission band, leading to the white light emission. The broadening effect is found to increase with an increase in the ion fluence and porosity. XRD study revealed the relative resistance of the film against the irradiation, i.e., the irradiation of the structure failed to completely amorphize the structure, suggesting its possible application in optoelectronics and sensing applications under harsh radiation conditions. PMID:22748164

Kumar, Yogesh; Herrera-Zaldivar, Manuel; Olive-Méndez, Sion Federico; Singh, Fouran; Mathew, Xavier; Agarwal, Vivechana

2012-01-01

 
 
 
 
241

Influence of Electrolyte Chemistry on Morphology and Corrosion Resistance of Micro Arc Oxidation Coatings Deposited on Magnesium  

Science.gov (United States)

In the present work, micro arc oxidation (MAO) coatings were synthesized on magnesium substrate employing 11 different electrolyte compositions containing systematically varied concentrations of sodium silicate (Na2SiO3), potassium hydroxide (KOH), and sodium aluminate (NaAlO2). The resultant coatings were subjected to coating thickness measurement, energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), image analysis, and three-dimensional (3-D) optical profilometry. The corrosion performance of the coatings was evaluated by conducting potentiodynamic polarization tests in 3.5 wt pct NaCl solution. The inter-relationships between the electrolyte chemistry and the resulting chemistry and porosity of the coating, on one hand, and with the aqueous corrosion behavior of the coating, on the other, were studied. The changes in pore morphology and pore distribution in the coatings were found to be significantly influenced by the electrolyte composition. The coatings can have either through-thickness pores or pores in the near surface region alone depending on the electrolyte composition. The deleterious role of KOH especially when its concentration is >20 pct of total electrolyte constituents promoting the formation of large and deep pores in the coating was demonstrated. A reasonable correlation indicating the increasing pore volume implying the increased corrosion was noticed.

Rama Krishna, L.; Poshal, G.; Sundararajan, G.

2010-12-01

242

Adsorption of nickel and copper onto natural iron oxide-coated sand from aqueous solutions: Study in single and binary systems  

Energy Technology Data Exchange (ETDEWEB)

Natural iron oxide-coated sand (NCS), extracted from the iron ore located in North-West of Tunisia, was employed to investigate its capacity to remove copper and nickel from aqueous solutions. The aim of this work was to characterize the considered sorbent (NCS) and to assess the possibility of removing nickel and copper from aqueous solutions by this sorbent. The effects of agitation time, pH, initial metal ion concentration and temperature on the removal of these metals were studied. In order to study the sorption isotherm, two equilibrium models, the Freundlich and Langmuir isotherms, were analyzed. The effect of solution pH on the adsorption onto NCS was studied in the pH range from 2 to 7 and 2 to 9 for copper and nickel respectively. The adsorption was endothermic and the computation of the parameters, {delta}H{sup o}, {delta}S{sup o} and {delta}G{sup o}, indicated that the interactions were thermodynamically favourable. Experiments with Cu and Ni adsorption measured together showed that Cu severely interfered with Ni adsorption to the NCS and vice versa under the conditions of the two coexisted ions adsorption.

Boujelben, N. [Laboratoire Eau Energie et Environnement, departement de genie geologique, Ecole Nationale d' Ingenieurs de Sfax, BP W 3038 Sfax (Tunisia)], E-mail: nesrine.boujelben@tunet.tn; Bouzid, J. [Laboratoire Eau Energie et Environnement, departement de genie geologique, Ecole Nationale d' Ingenieurs de Sfax, BP W 3038 Sfax (Tunisia)], E-mail: Jalel.bouzid@tunet.tn; Elouear, Z. [Laboratoire Eau Energie et Environnement, departement de genie geologique, Ecole Nationale d' Ingenieurs de Sfax, BP W 3038 Sfax (Tunisia)], E-mail: zouheir.elouaer@tunet.tn

2009-04-15

243

Adsorption of nickel and copper onto natural iron oxide-coated sand from aqueous solutions: Study in single and binary systems  

International Nuclear Information System (INIS)

Natural iron oxide-coated sand (NCS), extracted from the iron ore located in North-West of Tunisia, was employed to investigate its capacity to remove copper and nickel from aqueous solutions. The aim of this work was to characterize the considered sorbent (NCS) and to assess the possibility of removing nickel and copper from aqueous solutions by this sorbent. The effects of agitation time, pH, initial metal ion concentration and temperature on the removal of these metals were studied. In order to study the sorption isotherm, two equilibrium models, the Freundlich and Langmuir isotherms, were analyzed. The effect of solution pH on the adsorption onto NCS was studied in the pH range from 2 to 7 and 2 to 9 for copper and nickel respectively. The adsorption was endothermic and the computation of the parameters, ?Ho, ?So and ?Go, indicated that the interactions were thermodynamically favourable. Experiments with Cu and Ni adsorption measured together showed that Cu severely interfered with Ni adsorption to the NCS and vice versa under the conditions of the two coexisted ions adsorption

244

Structural and phase investigations of oxide coatings of TiO2 and Al2O3+13wt.%TiO2 after remelting  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: The purpose of this work was a microstructural and phase analysis of oxide layers remelted with TIG welding machine and by means of modified TIG method.Design/methodology/approach: The scope of investigations encompassed microstructural and phase assessment of oxide layers after remelting and alloying. Surface treatment was performed by means of TIG welding method and its modified version.Findings: Investigations of remelted coatings enabled determination of effect of the treatment on the structure and nature of phase transformations.Research limitations/implications: Further investigations with use of transmission electron microscopy will make it possible to observe the microstructures and obtain additional information about morphology of phases.Practical implications: Oxide coatings are one of the main components in coatings which are used under conditions of intensive wear and influence of corrosion agents.Originality/value: Modification of single-torch welding method was a solution to a problem of remelting of non-conducting ceramic coatings.

A. Dudek

2008-09-01

245

Decolorization of methylene blue by delta-MnO2-coated montmorillonite complexes: emphasizing redox reactivity of Mn-oxide coatings.  

Science.gov (United States)

Delta-MnO(2) coatings on clay substrates tend to be poorer in crystallinity as compared with their discrete counterparts, which may be of environmental significance for adsorption and oxidation of contaminants. Discrete delta-MnO(2) particles and three delta-MnO(2)-coated montmorillonite complexes with varying MnO(2) loadings (4.8-34.9%) were synthesized, and oxidative decolorization of methylene blue (MB) by the synthetic materials was investigated in batch systems. Results showed that oxidative decolorization of MB increased with increasing loading of Mn-oxide coatings, whereas oxidation capacity of the coatings, on the basis of unit mass of MnO(2), tended to decrease. Initial reaction rate of MB oxidation by both delta-MnO(2) coatings and their discrete counterpart increased linearly with increasing Mn-oxide loadings, but the rate of the former was higher than that of the latter. An increase in humic acid concentration displayed a progressively enhanced promotive effect on MB decolorization, whereas the promotive effect was greatly suppressed at lower pH. PMID:20510506

Zhu, Mao-Xu; Wang, Zheng; Xu, Shao-Hui; Li, Tie

2010-09-15

246

Pooled analysis of trials comparing titanium-nitride-oxide-coated stents with paclitaxel-eluting stents in patients undergoing coronary stenting.  

Science.gov (United States)

We performed a pooled analysis of three trials comparing titanium-nitride-oxide-coated bioactive stents (BAS) with paclitaxel-eluting stents (PES) in 1,774 patients. All patients were followed for 12 months. The primary outcomes of interest were recurrent myocardial infarction (MI), death and target lesion revascularization (TLR). Secondary endpoints were stent thrombosis (ST) and major adverse cardiac events (MACE) including MI, death and TLR. There were 922 patients in the BAS group and 852 in the PES group. BAS significantly reduced the risk of recurrent MI (2.7% vs. 5.6%; risk ratio 0.50, 95% CI 0.31-0.81; p = 0.004) and MACE (8.9% vs. 12.6%; risk ratio 0.71, 95% CI 0.54-0.94; p = 0.02) during the 12 months of follow up. In contrast, the differences between BAS and PES were not statistically significant with respect to TLR (risk ratio 0.98, 95% CI 0.68-1.41), death (risk ratio 0.96, 95% CI 0.61-1.51) and definite ST (risk ratio 0.28, 95% CI 0.05-1.47). In conclusion, the results of this analysis suggest that BAS is effective in reducing TLR and improves clinical outcomes by reducing MI and MACE compared with PES. PMID:20603504

Karjalainen, Pasi P; Biancari, Fausto; Ylitalo, Antti; Raeber, Lorentz; Billinger, Michael; Hess, Otto; Airaksinen, K E Juhani

2010-07-01

247

Di(isothiocyanato)bis(4-methyl-4’-vinyl-2,2’-bipyridine) Ruthenium(II) Films Deposited on Titanium Oxide-Coated, Fluorine-Doped Tin Oxide for an Efficient Solar Cell  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Dye-sensitized titanium oxide electrodes were prepared by immobilizing a novel ruthenium complex, di(isothiocy- anato)bis(4-methyl-4’-vinyl-2,2’-bipyridine)ruthenium(II) [(NCS)2(mvbpy)2Ru(II)] or the ruthenium complex/sodium 4-vinylbenzenesulfonate onto the surface of a titanium oxide-coated, fluorine-doped tin oxide (TiO2/FTO) electrode through a new electrochemically initiated film formation metho...

Yi Liu; Ryuichi Sugimoto; Katsuhiro Sumi

2013-01-01

248

Preparation and Characterization of Chitosan/Feldspar Biohybrid as an Adsorbent: Optimization of Adsorption Process via Response Surface Modeling  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Chitosan/feldspar biobased beads were synthesized, characterized, and tested for the removal of Acid Black 1 dye from aquatic phases. A four-factor central composite design (CCD) accompanied by response surface modeling (RSM) and optimization was used to optimize the dye adsorption by the adsorbent (chitosan/feldspar composite) in 31 different batch experiments. Independent variables of temperature, pH, initial dye concentration, and adsorbent dose were used to change to coded values. To anti...

Maryam Yazdani; Hajir Bahrami; Mokhtar Arami

2014-01-01

249

Removal of radioactive iodine from water using Ag2O grafted titanate nanolamina as efficient adsorbent.  

Science.gov (United States)

Emergency treatment of radioactive material leakage and safety disposal of nuclear waste is a constant concern all along with the development of radioactive materials applications. To provide a solution, titanate with large surface area (143 m(2)g(-1)) and a lamina morphology (the thickness of the lamina is in range of tens of nanometers) was prepared from inorganic titanium compounds by hydrothermal reactions at 433 K. Ag(2)O nanocrystals (5-30 nm) were deposited onto the titanate lamina. The surface of the titanate lamina has crystallographic similarity to that of Ag(2)O nanocrystals. Hence, the deposited Ag(2)O nanocrystals and titanate substrate join together at these surfaces, forming a well-matched phase coherent interface between them. Such coherence between the two phases reduces the overall energy by minimizing surface energy and anchors the Ag(2)O nanocrystals firmly on the external surface of the titanate structure. The composite thus obtained was applied as efficient adsorbent to remove radioactive iodine from water (one gram adsorbent can capture up to 3.4 mmol of I(-) anions). The composite adsorbent can be recovered easily for safe disposal. The structure changes of the titanate lamina and the composite adsorbent were monitored by various techniques. The isotherm and kinetics of iodine adsorption, competitive adsorption and column adsorption using the adsorbent were studied to assess its iodine removal abilities. The adsorbent exhibited a capacity as high as 3.4 mmol of iodine per gram of adsorbent in 1h. Therefore, Ag(2)O deposited titanate lamina is an effective adsorbent for removing radioactive iodine from water. PMID:23313892

Bo, Arixin; Sarina, Sarina; Zheng, Zhanfeng; Yang, Dongjiang; Liu, Hongwei; Zhu, Huaiyong

2013-02-15

250

Protective coatings based on composite materials  

International Nuclear Information System (INIS)

A study of the compatibility in compositions based on tungsten and molybdenum fibers with aluminum-oxide coatings in Nichrome matrices showed that a protective layer 1-3 ?m thick ensures stability of the reinforcing-phase-matrix contact at temperatures of 1100-1200 degrees C for 80-100 h. Yttrium, thorium, hafnium, and other oxides can also be used as barrier coatings, but they are brittle and sensitive to thermal shocks, and there is no universal method for depositing the oxides on continuous fibers

251

Stretching an adsorbed polymer globule  

CERN Document Server

Using molecular dynamic simulation, we study the stretching of an adsorbed homopolymer in a poor solvent with one end held at a distance $z_e$ from the substrate. We measure the vertical force $f$ on the end of the chain as a function of the extension $z_e$ and the substrate interaction energy $w$. The force reaches a plateau value at large extensions. In the strong adsorption limit, we show that the plateau value increase linearly in $w$ in good agreement with a theoretical model. In the weak adsorption limit, a polymer globule with a layered structure is formed and elastically deformed when stretched. In both cases a simple theoretical model permits us to predict the relation between the necessary force to fully detach the polymer and its critical extension.

Celestini, F; Oyharcabal, X; Celestini, Franck; Frisch, Thoma; Oyharcabal, Xabier

2004-01-01

252

Complete braided adsorbent for marine testing to demonstrate 3g-U/kg-adsorbent  

Energy Technology Data Exchange (ETDEWEB)

ORNL has manufactured four braided adsorbents that successfully demonstrated uranium adsorption capacities ranging from 3.0-3.6 g-U/kg-adsorbent in marine testing at PNNL. Four new braided and leno woven fabric adsorbents have also been prepared by ORNL and are currently undergoing marine testing at PNNL.

Janke, Chris [ORNL; Yatsandra, Oyola [ORNL; Mayes, Richard [ORNL; none,; Gill, Gary [PNNL; Li-Jung, Kuo [PNNL; Wood, Jordana [PNNL; Sadananda, Das [ORNL

2014-04-30

253

Effect of Micro-Arc Oxidation Coatings on Corrosion Resistance and Mechanical Properties of Closed-Cell Aluminum Foams  

Science.gov (United States)

Micro-arc oxidation (MAO) coatings were prepared on closed-cell aluminum foams. The microstructure, elemental distribution and phase composition of the MAO coatings were analyzed by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and X-ray diffraction (XRD), respectively. The corrosion resistances and compressive properties of the uncoated and coated aluminum foams were studied by electrochemical polarization test and mechanical test, respectively. The results show that the MAO coatings cover the surfaces of closed-cell aluminum foams. The average thickness of the MAO coatings is 7 ?m. The MAO coatings are mainly composed of ?-Al2O3 phase. The corrosion resistances of the closed-cell aluminum foams are improved by MAO treatment. The as-received foams show a low corrosion potential (-1.36 V), on contrary, the MAO coated foams get an increase corrosion potential (-0.78 V). But the MAO coated foams show the marginal variation in compressive strengths when the thickness of the coatings could be negligible compared with the total thickness of the foams.

Zhu, Xianyong; Liu, Jiaan

2013-10-01

254

Growth, microstructure and mechanical properties of microarc oxidation coatings on titanium alloy in phosphate-containing solution  

International Nuclear Information System (INIS)

Ceramic coatings were fabricated by microarc oxidation in galvanostatic regime on Ti6Al4V alloy in (NaPO3)6-NaF-NaAlO2 solution. The growth, microstructure and phase composition of coatings were investigated using scanning electron microscope and X-ray diffraction. With increasing treatment duration, coating growth varies from rapidness to tardiness accompanied by gradually roughening in appearance. Meanwhile, phase transformation of anatase to rutile occurs. The crystalline AlPO4 is involved in the coatings via high-temperature thermolysis of hydrated aluminium polyphosphates in the nearby discharging channels. The stepped current regime enables coating structure to be controllable. The mechanical properties distribution across the coating thickness and the adhesion strength were determined by nanoindentation and shear test, respectively. A similar evolution profile of hardness and elastic modulus across the coating thickness is found: remaining high values (5.5 and 69.1 GPa) in the compact region before finally declining to low values (5.1 and 65.6 GPa) in the looser region. The adhesion strength of substrate/coating interface is about 40 MPa

255

NMR study of nanophase Al/Al-oxide powder and consolidated composites  

International Nuclear Information System (INIS)

27Al Nuclear Magnetic Resonance (NMR) measurements from aluminum powders and consolidated nanophase aluminum made from those powders are presented. The signals from the metal and surface oxidation are easily separated and are compared before and after consolidation. The results presented indicate that the oxide coating becomes the interface region within the nanophase composite material and that during consolidation the metal has undergone a deformation equivalent to that seen for bulk material under a compressive strain of between 4% and 8%

256

Preparation and Performance of Pre-coated Carbon Layer for Carbon/Carbon Composites  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Pre-coated carbon layers on the surface of carbon/carbon composites were prepared firstly by slurry and high-temperature treatment for preparing the anti-oxidation coating with SiC concentration gradient. The micrographs and microstructures of the pre-coated carbon layer were characterized by SEM, Raman and XRD. The effects of different graphite content and carbonization temperature on the microstructure of pre-coated carbon layer were investigated. The bonding strength between the carbon lay...

Zhang Yu-lei, Li He-jun

2009-01-01

257

Fission product adsorbent impregnated with quinuclidene  

International Nuclear Information System (INIS)

Disclosed is a method for removing an alkyl halide from gas stream contaminated therewith which comprises contacting said gas stream with a particulate adsorbent impregnated with quinuclidene. The alkyl halide usually is an alkyl iodide comprising methyl iodide, optionally radioactive, and the preferred particulate adsorbent is activated carbon

258

Effect of reactive element oxide coatings on the high temperature oxidation behavior of a FeCrAl alloy  

International Nuclear Information System (INIS)

This paper reports that thin coatings of nitrate-converted oxides of Y, Zr, Hf, Ce, La, Ca, and Al have been applied to the surface of a Fe-18 weight percent (w/o) Cr-5 w/o Al alloy by hot-dipping. The influence of these coatings on the oxidation behavior of the alloy was studied at 1100 and 1200 degrees C. Results were also compared with the oxidation of a 1 w/o Hf-containing alloy of the same base composition, with or without the application of selected coatings. It was found that all of the coated FeCrAl samples, apart from that coated with aluminum oxide, developed extremely convoluted Al2O3 scales. Oxide ridges several times larger than those formed on the untreated alloy developed at the oxidation temperature. These convoluted scales showed good spallation resistance after isothermal testing, but failed under thermal cyclic conditions. A thin layer of sulfur was found everywhere at the scale/alloy interface. The primary effect of the surface coatings was to increase the number of buckles in the oxide at the early stage of oxidation. Growth of the buckled oxide into large ridges took place by way of aluminum vapor phase transport and oxide lateral growth. The results are discussed in relation to the effect of reactive elements in improving scale adhesion, and it is suggested that the mechanisms governing this effect may be different for Al2O3-forming and for Cr2O3-forming alloys3-forming alloys

259

Effect of high temperature oxidation prefab film on formation of micro-arc oxidation coatings on 6061aluminum alloy  

Science.gov (United States)

Ceramic coatings were formed by micro-arc oxidation (MAO) on 6061aluminum alloy with and without a high temperature oxidation prefab film under a constant voltage. The effect of the high temperature oxidation prefab film on the initial stage of growth process of the MAO ceramic coatings was studied in this paper. The results showed that the prefab film decreased the arc starting voltage and the arc starting time of the micro-arc oxidation, and promoted the evolution processes of the micro-discharge and the surface morphology of the coating. The prefab film and electrolyte composition, especially element P, participated in the formation of the coatings. The growth process of the micro-arc oxidation ceramic coatings on specimens with the prefab film consists of four steps. The first step is the formation of grain type of oxide lumps, the second step is the spread of the lumps like little worms along the specimen surface, the third step is the formation of many network areas with a number of linear materials like little worms, and the fourth step is the development of network areas into a continuous layer. However, at the same period, the growth process of micro-arc oxidation ceramic coatings on the specimens without the prefab film consists of two steps. The first step is the formation of a little grain type of oxide lumps, and the second step is the increase of the number of grain type of oxide lumps and the expansion of the lumps like little worms in line along the surface of specimens.

Dejiu, Shen; Jie, Zou; Lailei, Wu; Fangfei, Liu; Guolong, Li; Jingrui, Cai; Donglei, He; Haojie, Ma; Guirong, Jiang

2013-01-01

260

NOx adsorber and method of regenerating same  

Energy Technology Data Exchange (ETDEWEB)

New technologies, such as NOx adsorber catalytic converters, are being used to meet increasingly stringent regulations on undesirable emissions, including NOx emissions. NOx adsorbers must be periodically regenerated, which requires an increased fuel consumption. The present disclosure includes a method of regenerating a NOx adsorber within a NOx adsorber catalytic converter. At least one sensor positioned downstream from the NOx adsorber senses, in the downstream exhaust, at least one of NOx, nitrous oxide and ammonia concentrations a plurality of times during a regeneration phase. The sensor is in communication with an electronic control module that includes a regeneration monitoring algorithm operable to end the regeneration phase when a time rate of change of the at least one of NOx, nitrous oxide and ammonia concentrations is after an expected plateau region begins.

Endicott, Dennis L. (Peoria, IL); Verkiel, Maarten (Metamora, IL); Driscoll, James J. (Dunlap, IL)

2007-01-30

 
 
 
 
261

Preparation and tribological properties of self-lubricating TiO{sub 2}/graphite composite coating on Ti6Al4V alloy  

Energy Technology Data Exchange (ETDEWEB)

Highlights: Black-Right-Pointing-Pointer A TiO{sub 2}/graphite composite coating is produced on Ti alloy by one-step PEO process. Black-Right-Pointing-Pointer The TiO{sub 2}/graphite composite coating exhibits excellent self-lubricating behavior. Black-Right-Pointing-Pointer The self-lubricating composite coating improves the wear resistance by comparison to the conventional PEO coating. - Abstract: One-step plasma electrolytic oxidation (PEO) process in a graphite-dispersed phosphate electrolyte was used to prepare a graphite-containing oxide composite coating on Ti6Al4V alloy. The composition and microstructure of the oxide coatings produced in the phosphate electrolytes with and without addition of graphite were analyzed by X-ray diffractometer (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The tribological properties of the uncoated Ti6Al4V alloy and oxide coatings were evaluated using a reciprocating ball-on-disk tribometer. Results showed that the graphite-containing oxide composite coating can be successfully produced on Ti6Al4V alloy in the graphite-dispersed phosphate electrolyte using PEO process. The graphite-containing oxide composite coating registered much lower friction coefficient and wear rate than the uncoated Ti6Al4V alloy and the oxide coating without graphite under dry sliding condition, exhibiting excellent self-lubricating property.

Mu, Ming [The Ministry of Education Key Laboratory, Conveyance Tools and Equipment, East China Jiaotong University, Nanchang 330013 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Zhou, Xinjian, E-mail: zhouxj63@126.com [The Ministry of Education Key Laboratory, Conveyance Tools and Equipment, East China Jiaotong University, Nanchang 330013 (China); Xiao, Qian [The Ministry of Education Key Laboratory, Conveyance Tools and Equipment, East China Jiaotong University, Nanchang 330013 (China); Liang, Jun, E-mail: jliang@licp.cas.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Huo, Xiaodi [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2012-09-01

262

Biodegradable adsorbents for aquatic oil spills: Adsorbent capabilities and biodegradation rates  

International Nuclear Information System (INIS)

Polypropylene fibers are the most used type of adsorbent material for oil spill cleanup, yet disposal of these fibers after they are oil-soaked presents a problem since they are not biodegradable and either have to be incinerated or placed in special landfills. Ex-situ biodegradation of used adsorbents is being investigated as a means of circumventing those problems. Biodegradable natural-fiber adsorbents including cotton and wool fibers were tested to determine their oil adsorbing capacities as compared to polypropylene adsorbents. Experiments were also conducted to study degradation of the adsorbent and the adsorbed oil. The oil adsorbing capacities of all fibers tested were similar except for raw cotton, whose capacity was considerably higher. In closed environments where optimum conditions for degradation could be provided and controlled, cotton or wool fiber adsorbents could be destroyed by microbial activity within several weeks. The adsorbents were degraded first and their adsorbed oil released. This oil could be separated and recovered. Complete anaerobic degradation of a sweet crude oil could be accomplished within six months, while diesel fuel could be degraded within one week. 8 refs.,. 3 figs., 1 tab

263

Characterisation of the adsorbate-adsorbent interaction between drugs or pesticides and carbon/silica compounds / Charlotte May van Eeden  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Administering adsorbates such as activated charcoal can treat acute poisoning from chemicals and pesticides. It has been suggested that activated charcoal is an effective antidote for virtually all organic and inorganic compounds. The aim of this study was to characterise the adsorbate-adsorbent interactions. Adsorbents used were chitosan, activated charcoal, silica and humic acids. Adsorbates used were paracetamol, prazosin hydrochloride, cimetidine, fluoxetine hydrochlorid...

Eeden, Charlotte May

2004-01-01

264

Composites  

Science.gov (United States)

It is commonly known that the properties of sintered materials are strongly related to technological conditions of the densification process. This paper shows the sintering behavior of a NiAl-Al2O3 composite, and its individual components sintered separately. Each kind of material was processed via the powder metallurgy route (hot pressing). The progress of sintering at different stages of the process was tested. Changes in the microstructure were examined using scanning and transmission electron microscopy. Metal-ceramics interface was clean and no additional phases were detected. Correlation between the microstructure, density, and mechanical properties of the sintered materials was analyzed. The values of elastic constants of NiAl/Al2O3 were close to intermetallic ones due to the volume content of the NiAl phase particularly at low densities, where small alumina particles had no impact on the composite's stiffness. The influence of the external pressure of 30 MPa seemed crucial for obtaining satisfactory stiffness for three kinds of the studied materials which were characterized by a high dense microstructure with a low number of isolated spherical pores.

Chmielewski, M.; Nosewicz, S.; Pietrzak, K.; Rojek, J.; Strojny-N?dza, A.; Mackiewicz, S.; Dutkiewicz, J.

2014-11-01

265

Stent strut coverage of titanium-nitride-oxide coated stent compared to paclitaxel-eluting stent in acute myocardial infarction: TITAX-OCT study.  

Science.gov (United States)

Drug-eluting stents (DES) have reduced the rate of restenosis but recent studies have raised concern over the risk of late stent thrombosis (LST). Incomplete stent endothelialization and delayed vascular healing have been associated with LST. The titanium-nitride-oxide coated bio-active stent (BAS) has shown promising results in patients with acute coronary syndromes, but there is little long-term optical coherence tomography (OCT) data comparing BAS with DES. The TITAX-AMI trial is a prospective, randomized, multicenter trial comparing BAS to paclitaxel-eluting stent (PES) in 425 patients with acute myocardial infarction. A total of 18 patients (9 per group) with no major cardiac events during follow-up, were enrolled in this substudy >36 months (mean 47 months) after stent implantation. Quantitative coronary angiography was performed and stent strut endothelialization and vascular healing were assessed with OCT. The binary stent strut coverage was significantly higher in the BAS group compared with the PES group (99.6 vs. 89.2%, p < 0.001) and there were less malapposed struts in the BAS group (0.2 vs. 13.8%, respectively, p < 0.001). The neointimal hyperplasia (NIH) thickness (266 ± 166 vs. 126 ?m ± 126 ?m, p < 0.001) and percentage of NIH area (26.2 vs. 7.6%, p < 0.001) were greater in the BAS group than in the PES group. Late incomplete endothelialization was not uncommon after PES implantation. Stents in the BAS group were completely endothelialized. This difference may contribute to the more common LST after PES implantation in the TITAX-AMI trial. PMID:22362097

Lehtinen, Tuomas; Airaksinen, K E Juhani; Ylitalo, Antti; Karjalainen, Pasi P

2012-12-01

266

Heat transfer to the adsorbent in solar adsorption cooling device  

Science.gov (United States)

The article deals with design and construction of solar adsorption cooling device and with heat transfer problem in adsorber. The most important part of adsorption cooling system is adsorber/desorber containing adsorbent. Zeolith (adsorbent) type was chosen for its high adsorption capacity, like a coolant was used water. In adsorber/desorber occur, at heating of adsorbent, to heat transfer from heat change medium to the adsorbent. The time required for heating of adsorber filling is very important, because on it depend flexibility of cooling system. Zeolith has a large thermal resistance, therefore it had to be adapted the design and construction of adsorber. As the best shows the tube type of adsorber with double coat construction. By this construction is ensured thin layer of adsorbent and heating is quick in all volume of adsorbent. The process of heat transfer was experimentally measured, but for comparison simulated in ANSYS, too.

Pilat, Peter; Patsch, Marek; Papucik, Stefan; Vantuch, Martin

2014-08-01

267

Properties of water adsorbed in porous silica aerogels  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Silica aerogels have been prepared by hydrolysis and condensation of sols of composition TMOS-methanol-H2O with molar ratio TMOS:H2O=4:1 and volume ratio TMOS:methanol=0.2; 0.3; 0.4 and 0.6. Their true and apparent densities, BET surface area, total pore volume and pore size distribution have been systematically investigated as a function of densification heat treatment. The relaxation properties of water adsorbed on the highly reactive surface have been studied by dielectric and nuclear magn...

Da Silva, Adao A.; Donoso, Jose P.; Aegerter, Michel A.

1992-01-01

268

Site blocking effects on adsorbed polyacrylamide conformation  

Science.gov (United States)

The use of polymers as flocculating additives is a common practice in many manufacturing environments. However, exactly how these polymers interact with surfaces is relatively unknown. One specific topic which is thought to be very important to flocculation is an adsorbed polymer's conformation. Substantial amounts of previous work, mainly using simulations, have been performed to elucidate the theory surrounding adsorbed polymer conformations. Yet, there is little experimental work which directly verifies current theory. In order to optimize the use of polymer flocculants in industrial applications, a better understanding of an adsorbed polymer's conformation on a surface beyond theoretical simulations is necessary. This work looks specifically at site blocking, which has a broad impact on flocculation, adsorption, and surface modification, and investigated its effects on the resulting adsorbed polymer conformation. Experimental methods which would allow direct determination of adsorbed polymer conformational details and be comparable with previous experimental results were first determined or developed. Characterization of an adsorbed polymer's conformation was then evaluated using dynamic light scattering, a currently accepted experimental technique to examine this. This commonly used technique was performed to allow the comparison of this works results with past literature. Next, a new technique using atomic force microscopy was developed, building on previous experimental techniques, to allow the direct determination of an adsorbed polymer's loop lengths. This method also was able to quantify changes in the length of adsorbed polymer tails. Finally, mesoscopic simulation was attempted using dissipative particle dynamics. In order to determine more information about an adsorbed polymer's conformation, three different environmental factors were analyzed: an adsorbed polymer on a surface in water, an adsorbed polymer on a surface in aqueous solutions of varying ionic strength, and an adsorbed polymer on a surface functionalized with site blocking additives. This work investigated these scenarios using a low charge density high molecular weight cationic polyacrylamide. Three different substrates, for polymer adsorption were analyzed: mica, anionic latex, and glass. It was determined that, similar to previous studies, the adsorbed polymer layer thickness in water is relatively small even for high molecular weight polymers, on the order of tens of nanometers. The loop length distribution of a single polymer, experimentally verified for the first time, revealed a broad span of loop lengths as high as 1.5 microns. However, the bulk of the distribution was found between 40 and 260 nanometers. For the first time, previous theoretical predictions regarding the salt effect on adsorbed polymer conformation were confirmed experimentally. It was determined that the adsorbed polymer layer thickness expanded with increasing ionic strength of the solvent. Using atomic force microscopy, it was determined that the adsorbed polymer loop lengths and tail lengths increased with increasing ionic strength, supporting the results found using dynamic light scattering. The effect of the addition of site blocking additives on a single polymer's conformation was investigated for the first time. It was determined that the addition of site blocking additives caused strikingly similar results as the addition of salt to the medium. The changes in adsorbed polymer's loop lengths was found to be inconsistent and minimal. However, the changes in an adsorbed polymer's free tail length was found to increase with increasing site blocking additive levels. These results were obtained using either PDADMAC or cationic nanosilica as site blocking additives.

Brotherson, Brett A.

269

Inorganic chemically active adsorbents (ICAAs)  

International Nuclear Information System (INIS)

Oak Ridge National Laboratory (ORNL) researchers are developing a technology that combines metal chelation extraction technology and synthesis chemistry. They begin with a ceramic substrate such as alumina, titanium oxide or silica gel because they provide high surface area, high mechanical strength, and radiolytic stability. One preparation method involves silylation to hydrophobize the surface, followed by chemisorption of a suitable chelation agent using vapor deposition. Another route attaches newly designed chelating agents through covalent bonding by the use of coupling agents. These approaches provide stable and selective, inorganic chemically active adsorbents (ICAAs) tailored for removal of metals. The technology has the following advantages over ion exchange: (1) higher mechanical strength, (2) higher resistance to radiation fields, (3) higher selectivity for the desired metal ion, (4) no cation exchange, (5) reduced or no interference from accompanying anions, (6) faster kinetics, and (7) easy and selective regeneration. Target waste streams include metal-containing groundwater/process wastewater at ORNL's Y-12 Plant (multiple metals), Savannah River Site (SRS), Rocky Flats (multiple metals), and Hanford; aqueous mixed wastes at Idaho National Engineering Laboratory (INEL); and scrubber water generated at SRS and INEL. Focus Areas that will benefit from this research include Mixed Waste, and Subsurface Contaminants

270

States of water adsorbed on perindopril crystals  

Science.gov (United States)

The relationship between the structural state of adsorbed water, the crystal structure of the substances, and the solubility of the perindopril salt C19H32N2O5 · C4H11N in water was studied by IR spectroscopy and X-ray diffractometry. The high-frequency shift of the stretching vibrations of adsorbed water and the solubility depend on the crystal structure of the drug substance. A reversible chemical reaction occurred between the adsorbed water and the perindopril salt.

Stepanov, V. A.; Khmelevskaya, V. S.; Bogdanov, N. Yu.; Gorchakov, K. A.

2011-10-01

271

IR investigations of surfaces and adsorbates  

International Nuclear Information System (INIS)

Synchrotron infrared reflection-absorption measurements on single crystal metal surfaces with adsorbates have led to the determination of many key parameters related to the bonding vibrational modes and the dynamics of adsorbates. In particular, energy couplings between electrons and adsorbate motion have been shown to be a dominant mechanism on metal surfaces. Excellent agreement has been obtained with calculations for many of the observations, and the synergy between theory and experiment has led to a deeper understanding of the roles of electrons and phonons in determining the properties of interfaces and their roles in phenomena as diverse as friction, lubrication, catalysis and adhesion. Nonetheless, as the experiments are pushed harder, to describe such effects as co-adsorbed systems, disagreements continue to challenge the theory and our comprehension also is still evolving

272

IR investigations of surfaces and adsorbates  

CERN Document Server

Synchrotron infrared reflection-absorption measurements on single crystal metal surfaces with adsorbates have led to the determination of many key parameters related to the bonding vibrational modes and the dynamics of adsorbates. In particular, energy couplings between electrons and adsorbate motion have been shown to be a dominant mechanism on metal surfaces. Excellent agreement has been obtained with calculations for many of the observations, and the synergy between theory and experiment has led to a deeper understanding of the roles of electrons and phonons in determining the properties of interfaces and their roles in phenomena as diverse as friction, lubrication, catalysis and adhesion. Nonetheless, as the experiments are pushed harder, to describe such effects as co-adsorbed systems, disagreements continue to challenge the theory and our comprehension also is still evolving.

Gwyn, W

2001-01-01

273

Development of adsorbent for radioactive carbon dioxide  

International Nuclear Information System (INIS)

To develop an effective adsorbent for radioactive Carbon Dioxide, 14CO2, which is discharged to nearby atmosphere from nuclear power plants of CANDU type, we made some preliminary adsorbents and tested their abilities of CO2 removal. The chemical agents used was LiOH and we supported or impregnated it on the surface or the internal volume of activated Carbon(GW-H). The physical and chemical properties of various adsorbents were measured using methods such as XRD, BET. SEM images were taken to investigate the change of surface morphology of the adsorbents. Finally, amount of CO2 adsorption of them were verified under specific conditions. We found that mechanical mixing of LiOH and activated Carbon by Nitric Acid-treatment enhanced its CO2 removal efficiency to some degree

274

Scattering studies of pluronics adsorbed on laponite  

International Nuclear Information System (INIS)

Full text: The synthetic clay laponite is a versatile product in the colloid industry. It can form gel structures at low concentrations, which give rise to technologically interesting rheological properties, hence its use as a thickener in paint, emulsifying agents, etc. However these properties may be modified by the addition of adsorbing polymers. In this study we examined the effects of adsorbed Pluronic triblock copolymers [(poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)] layers on the structure and interactions of a laponite dispersion. Contrast variation small-angle neutron scattering (SANS) measurements were used to characterise the layer size and the amount of adsorbed polymer. These experiments show that polymer is present not only on the face of the clay particle, but extends or 'wraps' over the edge as well. Moreover, the trends in layer size and adsorbed amount are consistent with Marques and Joannys scaling theory for block copolymer adsorption

275

Spherical Adsorbers and Catalysts from Aluminium Oxides  

International Science & Technology Center (ISTC)

Development of Multiaimed Low-Waste Technology of Production of Spherical Aluminium Oxide and Catalysts and Adsorbents on its Base which Allows to Solve Urgent Ecological Problems in Various Branches of Industry

276

PERVAPORATION USING ADSORBENT-FILLED MEMBRANES  

Science.gov (United States)

Membranes containing selective fillers, such as zeolites and activated carbon, can improve the separation by pervaporation. Applications of adsorbent-filled membranes in pervaporation have been demonstrated by a number of studies. These applications include removal of organic co...

277

Defluoridization Using a Natural Adsorbent, Strychnos Potatorum  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The study assessed the suitability of low-cost natural adsorbent to effectively remediate fluoride contaminated water. The removal of fluoride from aqueous solution by using Strychnos Potatorum was studied in batch technique. Influence of pH, adsorbent dose, contact time, co ions, speed and initial concentration on the adsorption were investigated. The maximum removal of fluoride ion was obtained at pH 7. The removal of fluoride was expressed with Langmuir and Freundlich isotherm. It was foun...

Rayappan, S.; Jeyaprabha, B.

2014-01-01

278

Ordering of adsorbed species on quasicrystal surfaces  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract We present an overview of experimental studies of the structure of adsorbed atomic and molecular species on quasicrystal surfaces with a particular focus on those systems where quasiperiodic ordering of the adsorbate structure occurs. Atomic adsorption is illustrated with examples from studies of Fe, Si and Gd adsorption on the five-fold surface of $i$-Al-Pd-Mn. Overlayer structure is correlated with several physical parameters to identify trends. It is concluded that the...

Smerdon, Joseph Anthony; Wearing, Lisa H.; Parle, Joseph; Leung, Lydie; Sharma, Hem Raj; Ledieu, Julian; Mcgrath, Ronan

2008-01-01

279

Regenerable activated bauxite adsorbent alkali monitor probe  

Science.gov (United States)

A regenerable activated bauxite adsorber alkali monitor probe for field applications to provide reliable measurement of alkali-vapor concentration in combustion gas with special emphasis on pressurized fluidized-bed combustion (PFBC) off-gas. More particularly, the invention relates to the development of a easily regenerable bauxite adsorbent for use in a method to accurately determine the alkali-vapor content of PFBC exhaust gases.

Lee, Sheldon H. D. (Willowbrook, IL)

1992-01-01

280

Mesoporous Silica: A Suitable Adsorbent for Amines  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Mesoporous silica with KIT-6 structure was investigated as a preconcentrating material in chromatographic systems for ammonia and trimethylamine. Its adsorption capacity was compared to that of existing commercial materials, showing its increased adsorption power. In addition, KIT-6 mesoporous silica efficiently adsorbs both gases, while none of the employed commercial adsorbents did. This means that KIT-6 Mesoporous silica may be a good choice for integrated chromatography/gas sensing micro-devices.

Abdollahzadeh-Ghom Sara

2009-01-01

 
 
 
 
281

Mesoporous silica: a suitable adsorbent for amines.  

Science.gov (United States)

Mesoporous silica with KIT-6 structure was investigated as a preconcentrating material in chromatographic systems for ammonia and trimethylamine. Its adsorption capacity was compared to that of existing commercial materials, showing its increased adsorption power. In addition, KIT-6 mesoporous silica efficiently adsorbs both gases, while none of the employed commercial adsorbents did. This means that KIT-6 Mesoporous silica may be a good choice for integrated chromatography/gas sensing micro-devices. PMID:20628459

Zamani, Cyrus; Illa, Xavi; Abdollahzadeh-Ghom, Sara; Morante, J R; Romano Rodríguez, Albert

2009-01-01

282

Changes in protective oxide coating at the surface of ferritic-martensitic steels after long-term tests in lead- bismuth eutectic alloy, detected with the use of X-ray diffraction scanning  

International Nuclear Information System (INIS)

The X-ray study on the state of the protective oxide coatings, obtained through oxidation in the eutectic lead-bismuth alloy at 600 deg C on the fuel element mockup samples with the shell from the 16Kh12MVSBFR steel and fuel element shell from the 12Kh13M2S2 steel, is carried out. The studies were conducted before and after the fuel element test in the experimental reactor core with the Pb-Bi-coolant during 2000 h. The mockup is tested on the circulation stand in the lead-bismuth alloy flux

283

Removal of cyanide by eggshell as low-cost adsorbent  

Directory of Open Access Journals (Sweden)

Full Text Available Introduction: Cyanides as carbon-nitrogen radicals are very toxic compounds and highly harmful to humans and aquatic organisms. The efficacy of eggshells (ES was investigated in this research work as an adsorbent for the elimination of cyanide from polluted streams.Material and Methods: In this experimental study, the capability of ES to adsorb cyanide ions was conducted using a series of batch tests in a shaker-incubator instrument. For each batch run, 100 mL of solution containing a known initial concentration of cyanide and with the preferred level of pH was shacked. The effects of selected parameters such as pH (3-11, reaction time (5–60 min cyanide concentrations (50–150 mg/L and the adsorbent dosage (0.25–2 g/L were investigated on the removal cyanide as a target contaminate. Chemical composition ES were analyzed using a Philips model XL-30 scanning electron microscope (SEM with energy-dispersive X-ray microanalysis (EDX. The specific surface and pore size distributions of ES were measured via Brunauer-Emmett-Teller (BET isotherm and Barrett-Joyner-Halenda (BJH methods using a Micrometrics particle size analyzer. The concentration of cyanide in solution before and after treatment was determined using the titrimetric method as described in the standard methods.Results: Analysis of the ES component using the EDX technique showed that the main part of it consisted of calcium and its other components were magnesium, iron, aluminum and silicate. The experimental data showed that the maximum cyanide removal occurred at pH of 11, adsorbent dose (0.5 g/L and 40 min contact time. The kinetic evaluation indicated that the pseudo-second-order kinetic had the best fit to the experimental results predicting a chemisorption process. The equilibrium adsorption of cyanide onto ES was well represented by the Langmuir equation.Conclusion: As a result, ES as waste materials was revealed as a very efficient and low-cost adsorbent and a promising option for removing cyanide from industrial wastewaters.

Ghorban Asgari

2013-05-01

284

PHYSICAL CHARACTERIZATION AND DESULFURIZATION OF BIOBRIQUETTE USING CALCIUM-BASED ADSORBENT  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Combustion of coal and co-combustion of their co-fuel contribute to gas emissions. Among the gas emissions are SOx, NOx, CO and CO2. Introduction of calcium based adsorbent is addressed to absorb SO2 that release to the atmosphere during the combustion process. Objective of the research is at first to observe the physical characteristics of biobriquettes as a function of briquette compositions (coal to palm kernel shell ratios) and Ca/S ratios (Ca in adsorbent and S in briquette) using a natu...

Khairil; Asri Gani; Mahidin

2011-01-01

285

Neutron reflection study of bovine beta-casein adsorbed on OTS self-assembled monolayers.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Specular neutron reflection has been used to determine the structure and composition of bovine beta-casein adsorbed on a solid surface from an aqueous phosphate-buffered solution at pH 7. The protein was adsorbed on a hydrophobic monolayer self-assembled from deuterated octadecyltrichlorosilane solution on a silicon (111) surface. A two-layer structure formed consisting of one dense layer of thickness 23 +/- 1 angstroms and a surface coverage of 1.9 milligrams per square meter adjacent to the...

Fragneto, G.; Thomas, Rk; Rennie, Ar; Penfold, J.

1995-01-01

286

Defluoridization Using a Natural Adsorbent, Strychnos Potatorum  

Directory of Open Access Journals (Sweden)

Full Text Available The study assessed the suitability of low-cost natural adsorbent to effectively remediate fluoride contaminated water. The removal of fluoride from aqueous solution by using Strychnos Potatorum was studied in batch technique. Influence of pH, adsorbent dose, contact time, co ions, speed and initial concentration on the adsorption were investigated. The maximum removal of fluoride ion was obtained at pH 7. The removal of fluoride was expressed with Langmuir and Freundlich isotherm. It was found that the sufficient time for adsorption equilibrium of fluoride ion was 1 hour. The removal of fluoride ions was maximum for the adsorbent dosage of SP is 50mg/50ml. The fluoride adsorption was maximum at 60minutes. The adsorption of F- ion was maximum in the shaking speed of 120 rpm. The presence of interfering ions such as nitrate and carbonate showed positive effect while sulphate and chloride showed little negative effect and phosphate showed high negative effect for the adsorbent. The optimum initial fluoride concentration for SP adsorbent was 1mg/50ml.

S.Rayappan

2014-10-01

287

Protein purification using magnetic adsorbent particles  

DEFF Research Database (Denmark)

The application of functionalised magnetic adsorbent particles in combination with magnetic separation techniques has received considerable attention in recent years. The magnetically responsive nature of such adsorbent particles permits their selective manipulation and separation in the presence of other suspended solids. Thus, it becomes possible to magnetically separate selected target species directly out of crude biological process liquors (e.g. fermentation broths, cell disruptates, plasma, milk, whey and plant extracts) simply by binding them on magnetic adsorbents before application of a magnetic field. By using magnetic separation in this way, the several stages of sample pretreatment (especially centrifugation, filtration and membrane separation) that are normally necessary to condition an extract before its application on packed bed chromatography columns, may be eliminated. Magnetic separations are fast, gentle, scaleable, easily automated, can achieve separations that would be impossible or impractical to achieve by other techniques, and have demonstrated credibility in a wide range of disciplines, including minerals processing, wastewater treatment, molecular biology, cell sorting and clinical diagnostics. However, despite the highly attractive qualities of magnetic methods on a process scale, with the exception of wastewater treatment, few attempts to scale up magnetic operations in biotechnology have been reported thus far. The purpose of this review is to summarise the current state of development of protein separation using magnetic adsorbent particles and identify the obstacles that must be overcome if protein purification with magnetic adsorbent particles is to find its way into industrial practice.

Franzreb, M; Siemann-Herzberg, M.

2006-01-01

288

All-solid-state lithium secondary batteries with oxide-coated LiCoO{sub 2} electrode and Li{sub 2}S-P{sub 2}S{sub 5} electrolyte  

Energy Technology Data Exchange (ETDEWEB)

All-solid-state lithium secondary batteries using LiCoO{sub 2} active materials coated with Li{sub 2}SiO{sub 3} and SiO{sub 2} oxide films and Li{sub 2}S-P{sub 2}S{sub 5} solid electrolytes were fabricated and their electrochemical performance was investigated. The electrochemical performace of the all-solid-state cells at a high voltage region was highly improved by using oxide-coated LiCoO{sub 2}. The oxide coatings are effective in suppressing the formation of an interfacial resistance between LiCoO{sub 2} and the solid electrolyte at a high cutoff voltage of 4.6 V (vs. Li). As a result, charge-discharge capacities and cycle performance at the cutoff voltage were improved. The cell with Li{sub 2}SiO{sub 3}-coated LiCoO{sub 2} showed a large initial discharge capacity of 130 mAh g{sup -1} and a good capacity retention of 110 mAh g{sup -1} after 50th cycles at the cutoff voltage of 4.6 V (vs. Li). (author)

Sakuda, Atsushi; Kitaura, Hirokazu; Hayashi, Akitoshi; Tadanaga, Kiyoharu; Tatsumisago, Masahiro [Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan)

2009-04-01

289

Computer Simulations of Adsorbed Polymer Chains  

International Nuclear Information System (INIS)

The simple cubic lattice model of polymer chains was used to study the properties of adsorbed macromolecules with different internal architectures: linear chains and star-branched chains with 3 arms of equal lengths. The polymer chains were modeled with the excluded volume interactions only, i.e. in good solvent conditions. The chains were placed on an impenetrable surface and a contact potential between polymer segments and this surface was assumed. The strength of this potential was chosen to emulate the conditions of a weak adsorption regime. The Metropolis-like sampling Monte Carlo algorithm was used to determine the properties of the adsorbed polymer film. The size and the internal structure of adsorbed chains were described. The size, distribution and lifetimes of structural elements such as tails, loops and trains were also determined. The differences between the structure of films consisting of star-branched and linear chains were described and discussed. (author)

290

Standoff Spectroscopy of Surface Adsorbed Chemicals  

Energy Technology Data Exchange (ETDEWEB)

Despite its immediate applications, selective detection of trace quantities of surface adsorbed chemicals, such as explosives, without physically collecting the sample molecules is a challenging task. Standoff spectroscopic techniques offer an ideal method of detecting chemicals without using a sample collection step. Though standoff spectroscopic techniques are capable of providing high selectivity, their demonstrated sensitivities are poor. Here we describe standoff detection of trace quantities of surface adsorbed chemicals using two quantum cascade lasers operated simultaneously, with tunable wavelength windows that match with absorption peaks of the analytes. This standoff method is a variation of photoacoustic spectroscopy, where scattered light from the sample surface is used for exciting acoustic resonance of the detector. We demonstrate a sensitivity of 100 ng/cm{sup 2} and a standoff detection distance of 20 m for surface adsorbed analytes such as explosives and tributyl phosphate.

Van Neste, Charles W [ORNL; Senesac, Larry R [ORNL; Thundat, Thomas George [ORNL

2009-01-01

291

Binary chromatographic data and estimation of adsorbent porosities. [data for system n-heptane/n-pentane  

Science.gov (United States)

Data for the system n-pentane/n-heptane on porous Chromosorb-102 adsorbent were obtained at 150, 175, and 200 C for mixtures containing zero to 100% n-pentane by weight. Prior results showing limitations on superposition of pure component data to predict multicomponent chromatograms were verified. The thermodynamic parameter MR0 was found to be a linear function of sample composition. A nonporous adsorbent failed to separate the system because of large input sample dispersions. A proposed automated data processing scheme involving magnetic tape recording of the detector signals and processing by a minicomputer was rejected because of resolution limitations of the available a/d converters. Preliminary data on porosity and pore size distributions of the adsorbents were obtained.

Meisch, A. J.

1972-01-01

292

Tailoring fly ash activated with bentonite as adsorbent for complex wastewater treatment  

International Nuclear Information System (INIS)

Highlights: ? The spent adsorbent annealed at 500 °C can be a suggestion for padding in stone blocks. ? The cations can be adsorbent by the silanol group (Si-OH) of the layers from bentonite ? Copper has a higher affinity for the active sites on adsorbent FAw + B than cadmium. ? This substrate can be recommended for simultaneous removal of heavy metals and MB. ? FAw + B is recommended for wastewater treatment resulted in the dyes finishing industry. - Abstract: Used as adsorbent, alkali fly ash represents a low cost solution for advanced wastewater treatment. The alkali treatment raises sustainability issues therefore, in this research we aim to replace alkali fly ash with washed fly ash (FAw). For improving the adsorption capacity of washed fly ash, bentonite powder (B) was added, as a natural adsorbent with a composition almost identical to the fly ash. The new adsorbent was characterized by AFM, XRD, FTIR, SEM, EDS and the surface energy was evaluated by contact angle measurements. For understanding the complex adsorption process on this mixed substrate, preliminary tests were developed on synthetic wastewaters containing a single pollutant system (heavy metal), binary (two-heavy metals) and ternary (dye and two heavy metals) systems. Experiments were done on synthetic wastewaters containing methylene blue, cadmium and copper, using FAw, B and their powder mixtures. The pseudo-second order kinetics could well model all the processes, indicating a good adprocesses, indicating a good adsorbent material which can be used for the pollutants removal from wastewater. After adsorption the substrates loaded with pollutants, annealed at 500 °C can be reused for padding in stone blocks.

293

INTERACTION OF CARBON DIOXIDE WITH CARBON ADSORBENTS BELOW 400 C  

Energy Technology Data Exchange (ETDEWEB)

The adsorption of carbon dioxide on carbon adsorbents (FT carbon, coconut charcoal, acid-washed bone char) and adsorbents containing basic calcium phosphate (hydroxylapatite, bone char, ash of bone char) was studied. Special consideration was given to the pretreatment of the materials. The carbons equilibrated as rapidly as the temperature; the basic calcium phosphates showed a rapid initial adsorption followed by a very slow rate which continued for days. Linear adsorption isotherms were found on FT carbon and the isosteric heats varied slightiy with coverage. The isotherms for the remaining materials had varying curvature and were for the most part in the same sequence as the estimated surface areas. The isosteric heats of carbon dioxide correlated very well with the magnitude of surface hydroxyl groups, an estimate of which was made from the chemical composition. There appeared to be three increasing levels of interaction: (1) pure physical adsorption; (2) an adsorption complex having 'bicarbonate structure'; and (3) an adsorption complex having 'carbonate structure'. (auth)

Deitz, V.R.; Carpenter, F.G.; Arnold, R.G.

1963-06-15

294

Fly ash adsorbents for multi-cation wastewater treatment  

International Nuclear Information System (INIS)

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 Pb2+, Cd2+ and Zn2+ cations from mixed solutions. The results show high efficiency and selective adsorption the Pb2+ and Zn2+ cations. The optimized adsorption parameters were further used in thermodynamic and kinetic studies of the adsorption processes. The Langmuir and Freundlich models were used to describe the processes. The pseudo-second order kinetics could well model all the processes, indicating a surface concentration of the adsorption sites with the same order of magnitude as the cation concentrations.

295

Optimization of the preparation process of biological sludge adsorbents for application in water treatment.  

Science.gov (United States)

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°C 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 the addition of binding agent before the activation, and (iv) total disappearance of carbonyl groups from sample surfaces with the addition of humic acid or clayey soil as binder. All these adsorbents had a low C content. The capacity of these sludge-derived materials to adsorb methylene blue, 2,4-dichlorophenol, tetracycline, and (Cd(II)) was studied. Their adsorption capacity was considerably increased by the chemical activation but reduced by the pre-activation addition of a binding agent (humic acid, phenolic resin, and clayey soil). PMID:22472426

Gómez-Pacheco, C V; Rivera-Utrilla, J; Sánchez-Polo, M; López-Peñalver, J J

2012-05-30

296

Amine-tethered solid adsorbents coupling high adsorption capacity and regenerability for CO2 capture from ambient air.  

Science.gov (United States)

Silica supported poly(ethyleneimine) (PEI) materials are prepared via impregnation and demonstrated to be promising adsorbents for CO(2) capture from ultra-dilute gas streams such as ambient air. A prototypical class 1 adsorbent, containing 45 wt% PEI (PEI/silica), and two new modified PEI-based aminosilica adsorbents, derived from PEI modified with 3-aminopropyltrimethoxysilane (A-PEI/silica) or tetraethyl orthotitanate (T-PEI/silica), are prepared and characterized by using thermogravimetric analysis and FTIR spectroscopy. The modifiers are shown to enhance the thermal stability of the polymer-oxide composites, leading to higher PEI decomposition temperatures. The modified adsorbents present extremely high CO(2) adsorption capacities under conditions simulating ambient air (400 ppm CO(2) in inert gas), exceeding 2 mol(CO?(2)) kg(sorbent)(-1), as well as enhanced adsorption kinetics compared to conventional class 1 sorbents. The new adsorbents show excellent stability in cyclic adsorption-desorption operations, even under dry conditions in which aminosilica adsorbents are known to lose capacity due to urea formation. Thus, the adsorbents of this type can be considered promising materials for the direct capture of CO(2) from ultra-dilute gas streams such as ambient air. PMID:21548105

Choi, Sunho; Gray, McMahan L; Jones, Christopher W

2011-05-23

297

Adsorbate induced vacancy formation on silver surfaces.  

Science.gov (United States)

The energy required to form and remove vacancies on metal surfaces mediates the rate of mass transport during a wide range of processes. These energies are known to be sensitive to environmental conditions. Here, we use electronic structure density functional theory calculations to show that the surface vacancy formation energy of silver changes markedly in the presence of adsorbed and dissolved oxygen. We found that adsorbed atomic oxygen can reduce the surface vacancy formation energy of the Ag(111) surface by more than 30%, whereas surface vacancy formation becomes exothermic in the presence of pure subsurface oxygen. We went on to show that the total directionality of the topologically defined bond paths can be used to understand these changes. The resulting structure-property relationship was used to predict the behavior of silver in different atmospheres. We show that the surface vacancy formation energy decreases when electronegative elements are adsorbed on the surface, but that it can increase when electropositive elements are adsorbed. PMID:24695725

Jones, Travis E; Rocha, Tulio C R; Knop-Gericke, Axel; Stampfl, Catherine; Schlögl, Robert; Piccinin, Simone

2014-05-21

298

Photoemission spectroscopy of surfaces and adsorbates  

International Nuclear Information System (INIS)

Core level photoelectron spectroscopy is providing new information concerning the electronic properties of adsorbates and surfaces. Several examples will be discussed, including studies of adsorbed rare gas submonolayers and multilayers as well as clean metal surfaces. For rare gas multilayers adsorbed on metal surfaces, the photoelectrons and Auger electrons exhibit well-resolved increases in kinetic energy with decreasing distance between the excited atom and the substrate, allowing a direct labeling of the layers. These energy shifts are mainly due to the substrate screening effects, and can be described well by an image-charge model. For a Kr/Xe bilayer system prepared by first coating a Pd substrate with a monolayer of Kr and then overcoating with a layer of Xe, a thermally activated layer inversion process is observed when the temperature is raised, with Xe coming in direct contact with the substrate. For rare gas submonolayers adsorbed on the Al(111) surface, coverage-dependent core level shift and work function measurements provide information about the adatom spatial distributions, polarizabilities, and dipole moments for the ground and excited states. We have also studied the 2p core level shifts for a clean Al(001) surface relative to the bulk. The shifts have a large contribution from the initial-state effects

299

Magnetically supported zeolite adsorbents for effluent treatment  

International Nuclear Information System (INIS)

An attempt was made to remove heavy metal ions from metallurgical effluents by means of magnetically supported fluidized bed column employing zeolite-magnetite complexes as adsorbents. The natural sorptive properties of acid modified clinoptilolite were used instead of synthetic beads. X-ray diffraction and DTA studies on the raw material confirmed that the main zeolite mineral was clinoptilolite. (author)

300

Radiolysis of nitrous oxide adsorbed on alumina  

International Nuclear Information System (INIS)

The effect of surface coverage and surface area on the radiolysis of adsorbed N2O on alumina at 77 K was studied. The source of gamma irradiation was 60Co at a rate of 0.5x104 Gy/h. The product yields of N2O decomposition were measured chromatographically according to nitrogen production and were taken from the ESR spectra of the oxygen ion-radicals (O-sub(r)) as well. The radiation-chemical yields, G, of O-sub(r) and N2 depended on the surface coverage in a similar manner and G(O-sub(r)) approximately 2G(N2) was found. An ionic mechanism was proposed for the radiolysis of adsorbed N2O on alumina describina the experimental dependences of G(O-sub(r)) and G(N2) on the N2O surface coverage, in which the energy of the ionizing radiation adsorbed by a solid is transferred to adsorbed N2O molecules by electrons. (Sz.J.)

 
 
 
 
301

Antiferromagnets Structure in Adsorbed O2 Monolayers  

DEFF Research Database (Denmark)

Neutron diffraction from monolayers of O2 adsorbed on graphite shows structural arrangements similar to the dense planes of bulk O2. At monolayer completion and above, a magnetic superlattice reflection shows well-developed antiferromagnetic order for T ? 10 K. The submonolayer phase also shows signs of antiferromagnetic correlations at low temperature.

Nielsen, Mourits; McTague, J. P.

1977-01-01

302

Adsorbed monolayers: Phase transitions and quantum effects  

International Nuclear Information System (INIS)

Phase transitions in adsorbed (two dimensional) fluids and in adsorbed layers of linear molecules are studied with a combination of path integral Monte Carlo (PIMC), Gibbs ensemble Monte Carlo and finite size scaling techniques. For a chemical (non additive) hard disc fluid the 'critical' non-additive, where the entropy drives phase separations set in, are presented. For a fluid with internal quantum states the gas-liquid coexistence region, tricritical- and triple points can be determined, a comparison with density functional (DFT) results shows good agreement for the freezing densities. Linear N2 molecules adsorbed on graphite (in the ?3 x ?3 structure) show a transition from a high temperature phase to a low temperature phase with herringbone ordering of the orientational degrees of freedom. The order of the transition is determined in the anisotropic planar rotor model by analysis of the correlation length ? near the transition temperature T0. The simulation data, extrapolated to T0, yield a large but finite ? at T0 demonstrating that the herringbone ordering is a weak first order transition. The effect of quantum fluctuations on the herringbone transition is quantified by PIMC and chemical simulation methods. Quasiclassical and quasi-harmonic calculations agree for high and low temperatures, respectively, but only PIMC gives satisfactory results over the entire temperature range. Rounding effects of the phase transition in aeffects of the phase transition in adsorbed layers of (N2)x(CO)1-x for x< 7 % are analyzed by Monte Carlo methods, the ground state ordering for the transition in the adsorbed pure CO system is discussed, using ab initio potentials

303

Nitric oxide adsorbed on zeolites: EPR studies  

Science.gov (United States)

CW-EPR studies of NO adsorbed on sodium ion-exchanged zeolites were focused on the geometrical structure of NO monoradical and (NO) 2 biradical formed on zeolites. The EPR spectrum of NO monoradical adsorbed on zeolite can be characterized by the three different g-tensor components and the resolved y-component hyperfine coupling with the 14N nucleus. Among the g-tensor components, the value of g zz is very sensitive to the local environment of zeolite and becomes a measure of the electrostatic field in zeolite. The temperature dependence of the g-tensor demonstrated the presence of two states of the Na-NO adduct, in rigid and rotational states. The EPR spectra of NO adsorbed on alkaline metal ion-exchanged zeolite and their temperature dependency are essentially the same as that on sodium ion-exchanged zeolite. On the other hand, for NO adsorbed on copper ion-exchanged zeolite it is known that the magnetic interaction between NO molecule and paramagnetic copper ion are observable in the spectra recorded at low temperature. The signals assigned to (NO) 2 biradical were detected for EPR spectrum of NO adsorbed on Na-LTA. CW-EPR spectra as well as their theoretical calculation suggested that the two NO molecules are aligned along their N?O bond axes. A new procedure for automatical EPR simulation is described which makes it possible to analyze EPR spectrum easily. In the last part of this paper, some instances when other nitrogen oxides were used as a probe molecule to characterize the zeolite structure, chemical properties of zeolites, and dynamics of small molecules were described on the basis of selected literature data reported recently.

Yahiro, Hidenori; Lund, Anders; Shiotani, Masaru

2004-05-01

304

Hierarchically porous aminosilica monolith as a CO2 adsorbent.  

Science.gov (United States)

A facile strategy is successfully developed for the centimeter-scale preparation of hierarchically porous aminosilica monolith as a CO2 adsorbent just by simple processes of solvent-evaporation-induced coating, self-assembly, and concentration of tetraethyl orthosilicate sol on the surface of a polymer foam template without any adhesive composite material or hydrothermal treatment. (3-Aminopropyl) trimethoxysilane is immobilized on the surface of silica monolith via a gas-phase procedure. The silica frameworks of the monolith mimic those of the polymer foam template at the macroscale, and the frameworks are composed of the SBA-15 structure at the nanoscale. The hierarchically porous structure demonstrates improved properties over the single-mode porous component, with the macroporous framework ensuring mechanical stability and good mass transport properties, while the smaller pores provide the functionality for CO2 adsorption. PMID:25017002

Ko, Young Gun; Lee, Hyun Jeong; Kim, Jae Yong; Choi, Ung Su

2014-08-13

305

The adsorber loop concept for the contact between seawater and adsorber granulate  

International Nuclear Information System (INIS)

The present paper deals with the so-called ''adsorber loop concept'' in which the adsorber granulate is carried along with the seawater to be processed in a loop-like configuration and is separated again from the depleted water before this is leaving the adsorption unit. This concept enables high seawater velocities thus reducing the required bed area. Theoretical considerations are presented together with experimental results from field tests. (orig.)

306

Interplay of adsorbate-adsorbate and adsorbate-substrate interactions in self-assembled molecular surface nanostructures  

DEFF Research Database (Denmark)

The adsorption of 2,6-naphthalenedicarboxylic acid (NDCA) molecules on the Ag(110), Cu(110), and Ag(111) surfaces at room temperature has been studied by means of scanning tunnelling microscopy (STM). Further supporting results were obtained using X-ray photoelectron spectroscopy (XPS) and soft X-ray absorption spectroscopy (XAS). On the Ag(110) support, which had an average terrace width of only 15 nm, the NDCA molecules form extended one-dimensional (1-D) assemblies, which are oriented perpendicular to the step edges and have lengths of several hundred nanometres. This shows that the assemblies have a large tolerance to monatomic surface steps on the Ag(110) surface. The observed behaviour is explained in terms of strong intermolecular hydrogen bonding and a strong surface-mediated directionality, assisted by a sufficient degree of molecular backbone flexibility. In contrast, the same kind of step-edge crossing is not observed when the molecules are adsorbed on the isotropic Ag(111) or more reactive Cu(110)surfaces. On Ag(111), similar 1-D assemblies are formed to those on Ag(110), but they are oriented along the step edges. On Cu(110), the carboxylic groups of NDCA are deprotonated and form covalent bonds to the surface, a situation which is also achieved on Ag(110) by annealing to 200 degrees C. These results show that the formation of particular self-assembled molecular nanostructures depends significantly on a subtle balance between the adsorbate-adsorbate and adsorbate-substrate interactions and that kinetic factors play an important role.

Schnadt, Joachim; Xu, Wei

2010-01-01

307

Calculation of elastic diffuse LEED intensities from disordered adsorbates  

International Nuclear Information System (INIS)

To calculate the diffuse intensity distribution produced by low-energy electrons elasticity scattered from an adsorbate randomly adsorbed on locally identical sites on an otherwise clean crystal surface, and (optionally) to derive from this a Y-function characteristic of the local bonding geometry of the adsorbate. (orig.)

308

A novel adsorbent photocatalyst consisting of titania and mesoporous silica nanoparticles  

International Nuclear Information System (INIS)

The nanoscale combination of crystalline titania and mesoporous silica particles was successfully applied as a photocatalytic adsorbent for the rapid removal from air and complete decomposition of organic molecules. The composites consisted of anatase particles ca. 7 nm in diameter and mesoporous silica particles 10-100 nm in diameter, which provided a specific surface area of more than 1000 m2/g. The composites were prepared through the assembly of surfactant micelles and siliceous species in the presence of the titania nanoparticles. Acetaldehyde was quickly removed from air due to the large surface area of the mesoporous silica and then was gradually decomposed into carbon dioxide under UV illumination with mass transfer between the adsorbent and the titania photocatalyst

309

A novel adsorbent photocatalyst consisting of titania and mesoporous silica nanoparticles  

Energy Technology Data Exchange (ETDEWEB)

The nanoscale combination of crystalline titania and mesoporous silica particles was successfully applied as a photocatalytic adsorbent for the rapid removal from air and complete decomposition of organic molecules. The composites consisted of anatase particles ca. 7 nm in diameter and mesoporous silica particles 10-100 nm in diameter, which provided a specific surface area of more than 1000 m{sup 2}/g. The composites were prepared through the assembly of surfactant micelles and siliceous species in the presence of the titania nanoparticles. Acetaldehyde was quickly removed from air due to the large surface area of the mesoporous silica and then was gradually decomposed into carbon dioxide under UV illumination with mass transfer between the adsorbent and the titania photocatalyst.

Uchiyama, Hiroaki [Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku, Yokohama 223-8522 (Japan); Suzuki, Keisei [Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku, Yokohama 223-8522 (Japan); Oaki, Yuya [Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku, Yokohama 223-8522 (Japan); Imai, Hiroaki [Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku, Yokohama 223-8522 (Japan)]. E-mail: hiroaki@applc.keio.ac.jp

2005-11-25

310

Properties of adsorbates as open quantum systems  

Science.gov (United States)

We have recently developed a novel cluster-model approach to investigate adsorbate-surface systems. In our approach, a physically relevant subsystem is described as an open quantum system by considering a model cluster subject to the outgoing-wave boundary condition (OBC) at the edge of the cluster. We refer to this model as an open-boundary cluster model (OCM). Many known disadvantages of the conventional cluster-model approach, in which a model cluster is treated as an isolated system, have been remedied by introducing the OBC, whereas the local picture inherent in cluster models still remains valid. In our present research, the adsorption energy and the electron-transfer rate from adsorbates to surfaces are calculated with the OCM. Their dependences on the adsorption-distance and the Fermi energy are reasonably explained by analyzing the quasi-diabatic energy levels based on the local picture of adsorption.

Yasuike, Tomokazu; Nobusada, Katsuyuki

2008-10-01

311

Zeolites as alcohol adsorbents from aqueous solutions  

Directory of Open Access Journals (Sweden)

Full Text Available The potential usage of zeolites as adsorbents for the removal of organic molecules from water was investigated in a series of experiments with aqueous solutions of lower alcohols. This could represent a simple solution to the problem of cleaning up industrial wastewater as well as recovering valuable chemicals at relatively low costs. Adsorption isotherms of the Langmuir type were applied, and calculations showed that the amount of propanol adsorbed on silicalite corresponded to approximately 70% of the pore volume. The adsorption process is simple, and recovery of the more concentrated products is easily done by heat treatment and/or at lowered pressures. Adsorption experiments with aqueous acetone showed that silicalite had approximately the same adsorption capacity for acetone as for n-propanol. Heats of adsorption were determined calorimetrically.

Cekova Blagica

2006-01-01

312

Non-Equilibrium in Adsorbed Polymer Layers  

CERN Document Server

High molecular weight polymer solutions have a powerful tendency to deposit adsorbed layers when exposed to even mildly attractive surfaces. The equilibrium properties of these dense interfacial layers have been extensively studied theoretically. A large body of experimental evidence, however, indicates that non-equilibrium effects are dominant whenever monomer-surface sticking energies are somewhat larger than kT, a common case. Polymer relaxation kinetics within the layer are then severely retarded, leading to non-equilibrium layers whose structure and dynamics depend on adsorption kinetics and layer ageing. Here we review experimental and theoretical work exploring these non-equilibrium effects, with emphasis on recent developments. The structure and dynamics in non-equilibrium polymer layers adsorbed from dilute polymer solutions and from polymer melts and more concentrated solutions is discussed. Two distinct classes of behaviour arise, depending on whether physisorption or chemisorption is involved. A g...

O'Shaughnessy, B

2005-01-01

313

Adsorbents for radioactive organic solvent wastes  

International Nuclear Information System (INIS)

Purpose: To enable to settle radioactive solvents such as tributyl phosphate (TBP) and n-dodecane as they are without using hydrophobicizing agent such as quaternary ammonium salts. Constitution: The adsorbents are prepared by replacing interlaminer ions of swelling-type synthetic mica with alkaline earth metals or metal ions. For instance, synthetic micas introduced with Zr4+ or Ca2+ between the layers provide quite different functions from those of starting materials due to the properties of ions introduced between the layers. That is, they provide an intense affinity to organic phosphates such as TBP and transform into material showing a property of adsorbing and absorbing them. Particularly, the fixing nature to the phosphor content constituting TBP is significantly increased. (Horiuchi, T.)

314

Magnesium silicates adsorbents of organic compounds  

Science.gov (United States)

Studies were presented on production of highly dispersed magnesium silicate at a pilote scale. The process of silicate adsorbent production involved precipitation reaction using water glass (sodium metasilicate) solution and appropriate magnesium salt, preceded by an appropriate optimization stage. Samples of best physicochemical parameters were in addition modified (in order to introduce to silica surface of several functional groups) using the dry technique and various amounts of 3-isocyanatepropyltrimethoxysilane, 3-thiocyanatepropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane. The so prepared samples were subjected to a comprehensive physicochemical analysis. At the terminal stage of studies attempts were made to adsorb phenol from its aqueous solutions on the surface of unmodified and modified magnesium silicates. Particle size distributions were determined using the ZetaSizer Nano ZS apparatus. In order to define adsorptive properties of studied magnesium silicates isotherms of nitrogen adsorption/desorption on their surfaces were established. Efficiency of phenol adsorption was tested employing analysis of post-adsorption solution.

Ciesielczyk, Filip; Krysztafkiewicz, Andrzej; Jesionowski, Teofil

2007-08-01

315

Computer simulations of adsorbed liquid crystal films  

Science.gov (United States)

The structures adopted by adsorbed thin films of Gay-Berne particles in the presence of a coexisting vapour phase are investigated by molecular dynamics simulation. The films are adsorbed at a flat substrate which favours planar anchoring, whereas the nematic-vapour interface favours normal alignment. On cooling, a system with a high molecule-substrate interaction strength exhibits substrate-induced planar orientational ordering and considerable stratification is observed in the density profiles. In contrast, a system with weak molecule-substrate coupling adopts a director orientation orthogonal to the substrate plane, owing to the increased influence of the nematic-vapour interface. There are significant differences between the structures adopted at the two interfaces, in contrast with the predictions of density functional treatments of such systems.

Wall, Greg D.; Cleaver, Douglas J.

2003-01-01

316

Novel fungus-titanate bio-nanocomposites as high performance adsorbents for the efficient removal of radioactive ions from wastewater.  

Science.gov (United States)

Reclaimable adsorbents have a critical application in the adsorption of radioactive materials. In this study, the novel bio-nanocomposites comprising fungi and titanate nanotubes are successfully synthesized by a simple and low-cost method. Morphological characterizations and composite mechanism analysis confirm that the composites are sufficiently stable to avoid dust pollution resulting from the titanate nanomaterials. Adsorption experiments demonstrate that the bio-nanocomposites are efficient adsorbents with a saturated sorption capacity as high as 120 mg g(-1) (1.75 meq. g(-1)) for Ba(2+) ions. The results suggest that the bio-nanocomposites can be used as promising radioactive adsorbents for removing radioactive ions from water caused by nuclear leakage. PMID:24287628

Xu, Mingze; Wei, Guodong; Liu, Na; Zhou, Liang; Fu, Chengwei; Chubik, M; Gromov, A; Han, Wei

2014-01-21

317

Kenaf Core as CO2 Adsorbent  

Directory of Open Access Journals (Sweden)

Full Text Available Kenaf is a green engineering material that has a great potential to be used as CO2 adsorbent. To enhance the capability of kenaf core as CO2 adsorbent, it should be cleaned and modified via various kinds of treatments. Prior to treatment process, the sample should be cleaned to remove all the adherent extraneous matters. In this study, kenaf core sample has been cleaned by using different types of cleaning methods such as using distilled water at room and boiling water, NaOH solution and HCl solution. This study revealed that the cleaning by using distilled water at room temperature is the most efficient way as compared to other methods. Scanning Electron Microscope (SEM carried out showed that the surface of kenaf core after cleaned by using distilled water at room temperature indicates an open cylindrical channel with similar size of honeycomb shape gaps that is beneficial to provide an active site for CO2 to be trapped or adsorbed. CO2 adsorption study conducted in Pressure Swing Adsorption (PSA column showed that kenaf core sample after cleaning by using distilled water at room temperature could adsorb CO2 up to 84.45% and relatively higher than the other methods. This study also revealed that 5 min is sufficient for adsorption to take place. Further increase in the adsorption time does not indicate any significant change to the percentage of CO2 adsorption. The future works may involve a treatment and modification of kenaf core to enhance the CO2 adsorption process.

N. Zaini

2014-01-01

318

Elastic behavior of adsorbed polymer chains.  

Science.gov (United States)

Elastic behaviors of single polymer chains adsorbed on the attractive surface are first investigated using Monte Carlo simulation method based on the bond fluctuation model. We investigate the chain size and shape of adsorbed chains, such as mean-square radius of gyration S2, mean-square bond length b2, shape factors sf(i) and delta*, and the orientation of chain segments P2cos theta>, to illuminate how the shape of polymer chains changes during the process of tensile elongation. There are some special behaviors of the chain size and shape at the beginning of elongation, especially for strong attraction interaction. For example, mean fraction of adsorbed segments decreases abruptly in the region of small elongation ratio and then decreases slowly with increasing elongation ratio. In fact, the chain size and shape also changes abruptly for small elongation ratio with strong attraction interaction. Some thermodynamics properties are also investigated here. Average Helmholtz free energy increases fast for elongation ratio lambda1.15. Similar behaviors are obtained for average energy per bond. Elastic force (f ) and energy contribution to force (f(U)) are also studied, and we find that elastic force decreases abruptly for lambda<1.15, and there is a minimum of elastic force for strong attraction interaction, then increases very slowly with increasing elongation ratio. However, there are different behaviors for weak attraction interaction. For energy contribution to force (f(U)), there is a maximum value for strong attraction interaction in the region of lambda<1.15. Some comparisons with the atomic force microscopy experiments are also made. These investigations may provide some insights into the elastic behaviors of adsorbed polymer chains. PMID:15634108

Chen, Jin; Zhang, Linxi; Cheng, Jun

2004-12-01

319

Adsorbate-limited conductivity of graphene  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present a theory of electronic transport in graphene in the presence of randomly placed adsorbates. Our analysis predicts a marked asymmetry of the conductivity about the Dirac point, as well as a negative weak-localization magnetoresistivity. In the region of strong scattering, renormalization group corrections drive the system further towards insulating behavior. These results explain key features of recent experiments, and are validated by numerical transport computati...

Robinson, John P.; Schomerus, Henning; Oroszlany, Laszlo; Falko, Vladimir I.

2008-01-01

320

Adsorbent density impact on gas storage capacities  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the literature, different approaches, terminologies, concepts and equations are used for calculating gas storage capacities. Very often, these approaches are not well defined, used and/or determined, giving rise to significant misconceptions. Even more, some of these approaches, very much associated with the type of adsorbent material used (e.g., porous carbons or new materials such as COFs and MOFs), impede a suitable comparison of their performances for gas storage applications. We revie...

Kunowsky, Mirko; Sua?rez Garci?a, Fabia?n; Linares Solano, A?ngel

2013-01-01

 
 
 
 
321

Characterisation of lignite as an industrial adsorbent  

Energy Technology Data Exchange (ETDEWEB)

An alternative use of the abundant and inexpensive lignite (also known as brown coal) as an industrial adsorbent has been characterised. The adsorptive properties of two Victorian lignite without any pre-treatment were investigated using the cationic methylene blue dye as a model compound in aqueous solutions. Two commercial activated carbon products were also studied for comparison. The adsorption equilibrium of the four adsorbents was better described by the Langmuir isotherm model than the Freundlich model. The adsorption capacities of the two untreated lignite adsorbents, Loy Yang and Yallourn, calculated using Langmuir isotherms were 286 and 370 mg/g, respectively, higher than a coconut shell-based activated carbon (167 mg/g), but lower than a coal-based activated carbon (435 mg/g). Surface area results suggested that larger micropores and mesopores were important for achieving good methylene blue adsorption by the activated carbons. However, FTIR and cation exchange capacity analyses revealed that, for the lignite, chemical interactions between lignite surface functional groups and methylene blue molecules occurred, thereby augmenting its adsorption capacity. 63 refs., 3 figs., 7 tabs.

Ying Qi; Andrew F.A. Hoadley; Alan L. Chaffee; Gil Garnier [Monash University, Clayton, Vic. (Australia). Department of Chemical Engineering

2011-04-15

322

Linear electronic response of surfaces and adsorbates  

International Nuclear Information System (INIS)

The notion and the definition of the linear electronic surface response function and the corresponding surface electronic excitation spectrum are introduced through the quantum analog of the classical image theorem. General properties of the electronic excitation spectra of surfaces are discussed and reviewed by the help of several sum rules which these spectra should satisfy. Particular attention is paid to the discussion of the long wavelength limit of the surface electronic excitation spectra obtained from first principles calculations within well known models of free-electron surfaces, and for surfaces of some real metals obtained from constructions based on various data sources and matching procedures. This discussion is also complemented by a brief outline of the properties of the dynamic electronic response of chemisorbed adsorbates. Applications of the formalism of the response functions to problems of interactions of external probes with surfaces and adsorbed species, as e.g. in photoemission, ion and electron scattering from surfaces and adsorbates etc., are pointed out. (author). 23 refs, 7 figs

323

Adsorbent removal efficiencies for organic iodine compounds  

International Nuclear Information System (INIS)

The adsorbents used in nuclear air cleaning systems have been characterized in the past for removal efficiency of elemental iodine and methyl iodide. However, in several instances other iodine species have been suspected to be present for which the removal efficiency has been lower than for the above two forms; these are generally referred to as 'penetrating iodine species'. Analysis of carbons exposed to actual reactor release environments has indicated that these iodine compounds are organic compounds where the iodine is either attached to a different than methyl radical, or di and tri-iodomethanes. To characterize the removal efficiency of conventional impregnated adsorbents for these compounds a series of experiments were conducted with 131I tagged forms of these compounds both by themselves and in combination with methyl iodide. The adsorbents evaluated were stable iodine alone, tertiary amine alone and coimpregnated carbons. The results indicate that particularly the stable iodine alone impregnated carbons have significantly lower efficiency for the decontamination of these compounds while all carbons have lower removal efficiency for several of these compounds. (author)

324

Activity of Aflatoxins Adsorbents in Poultry Feed  

Directory of Open Access Journals (Sweden)

Full Text Available The flatoxins produced by Aspergillus flavus and A. parasiticus have been detected in various poultry feed resources. They have a negative affect on the performance of birds as the presence of Aflatoxins significantly inhibit the growth and productive performance of birds and even mortality in certain cases. They have also negative effect on the immune response of bird. The toxin binders e.g. Myco-Ad, Sorbatox and Mycofix-Plus have been claimed to adsorb or inactivate Aflatoxins in the body and thus reduce the toxicity effect of Aflatoxins. These toxin binders have also certain reports to adsorb various nutrients along with toxins resulting in their specific deficiency symptoms. The present study was designed to observe the effects of three different toxin binders in two phases on the performance of cross chicken (FAY x RIR in terms of weekly weight gain, feed consumption, feed conversion ratio and mortality. The results indicated that any product did not affect the performance of birds during five week of age. It showed that Myco-Ad, Sorbatox and Mycofix-Plus had no affect on the nutrient adsorption in poultry feed. During second phase the results indicated that all the three products significantly adsorbed Aflatoxins, which was reflected in terms of improved weight gain, feed conversion ratio and mortality of the birds.

Yasmin Mussaddeq

2000-01-01

325

Continuum Elastic Theory of Adsorbate Vibrational Relaxation  

CERN Document Server

An analytical theory is presented for the damping of low-frequency adsorbate vibrations via resonant coupling to the substrate phonons. The system is treated classically, with the substrate modeled as a semi-infinite elastic continuum and the adsorbate overlayer modeled as an array of point masses connected to the surface by harmonic springs. The theory provides a simple expression for the relaxation rate in terms of fundamental parameters of the system: $\\gamma = m\\bar{\\omega}_0^2/A_c \\rho c_T$, where $m$ is the adsorbate mass, $\\bar{\\omega}_0$ is the measured frequency, $A_c$ is the overlayer unit-cell area, and $\\rho$ and $c_T$ are the substrate mass density and transverse speed of sound, respectively. This expression is strongly coverage dependent, and predicts relaxation rates in excellent quantitative agreement with available experiments. For a half-monolayer of carbon monoxide on the copper (100) surface, the predicted damping rate of in-plane frustrated translations is $0.50\\times 10^{12}$~s$^{-1}$, a...

Lewis, S P; Mele, E J; Rappe, A M; Lewis, Steven P.; Rappe, Andrew M.

1997-01-01

326

Novel fungus-titanate bio-nanocomposites as high performance adsorbents for the efficient removal of radioactive ions from wastewater  

Science.gov (United States)

Reclaimable adsorbents have a critical application in the adsorption of radioactive materials. In this study, the novel bio-nanocomposites comprising fungi and titanate nanotubes are successfully synthesized by a simple and low-cost method. Morphological characterizations and composite mechanism analysis confirm that the composites are sufficiently stable to avoid dust pollution resulting from the titanate nanomaterials. Adsorption experiments demonstrate that the bio-nanocomposites are efficient adsorbents with a saturated sorption capacity as high as 120 mg g-1 (1.75 meq. g-1) for Ba2+ ions. The results suggest that the bio-nanocomposites can be used as promising radioactive adsorbents for removing radioactive ions from water caused by nuclear leakage.Reclaimable adsorbents have a critical application in the adsorption of radioactive materials. In this study, the novel bio-nanocomposites comprising fungi and titanate nanotubes are successfully synthesized by a simple and low-cost method. Morphological characterizations and composite mechanism analysis confirm that the composites are sufficiently stable to avoid dust pollution resulting from the titanate nanomaterials. Adsorption experiments demonstrate that the bio-nanocomposites are efficient adsorbents with a saturated sorption capacity as high as 120 mg g-1 (1.75 meq. g-1) for Ba2+ ions. The results suggest that the bio-nanocomposites can be used as promising radioactive adsorbents for removing radioactive ions from water caused by nuclear leakage. Electronic supplementary information (ESI) available: The experimental section and supplementary figures are shown in supplementary information. See DOI: 10.1039/c3nr03467d

Xu, Mingze; Wei, Guodong; Liu, Na; Zhou, Liang; Fu, Chengwei; Chubik, M.; Gromov, A.; Han, Wei

2013-12-01

327

Interaction forces between adsorbed polymer layers.  

Science.gov (United States)

The interaction forces between adsorbed polymer layers were investigated. Two types of graft copolymers that were adsorbed on hydrophobic surfaces have been investigated: (i) a graft copolymer consisting of polymethylmethacrylate/polymethacrylic acid back bone (the B chain) on which several poly(ethylene oxide) chains are grafted (to be referred to as PMMA/PEO(n)); and (ii) a graft copolymer consisting of inulin (linear polyfructose with degree of polymerization >23) (the A chain) on which several C(12) chains are grafted (INUTEC SP1). In the first case adsorbed layers of the graft copolymer were obtained on mica sheets and the interaction forces were measured using the surface force apparatus. In the second case the interaction forces were measured using Atomic Force Microscopy (AFM). For this purpose a hydrophobically modified glass sphere was attached to the tip of the cantilever of the AFM and the glass plate was also made hydrophobic. Both the sphere and the glass plate contained an adsorbed layer of INUTEC SP1. In the surface forces apparatus one essentially measures the energy E(D)-distance D curves for the graft copolymer of PMMA/PEO(n) between mica surfaces bearing the graft copolymer and this could be converted to interaction energy between flat surfaces. Using the de Gennes scaling theory, it is possible to calculate the interaction energy between the polymer layers. The same graft copolymer was used in latex dispersions and the high frequency modulus G'(?) was measured as a function of the volume fraction ? of the dispersion. This high frequency modulus could be related to the potential of mean force. In this way one could compare the results obtained from rheology and those obtained from direct measurement of interaction forces. In the AFM method, the interaction forces are measured in the contact area between two surfaces, i.e. a spherical glass particle and a glass plate. Both glass spheres and plates were hydrophobized using dichlorodimethylsilane. Results were obtained for adsorbed layers of INUTEC SP1 in water and in the presence of various concentrations of Na(2)SO(4) (0.3, 0.8, 1.0 and 1.5 mol dm(-3)). All results showed a rapid increase of force with a decrease of separation distance and the forces were still repulsive up to the highest Na(2)SO(4) concentration. This explains the high stability of dispersions when using INUTEC SP1 as stabilizer. PMID:21377642

Tadros, Tharwat

2011-07-11

328

The adsorber loop concept for the contact between seawater and adsorber granulate  

International Nuclear Information System (INIS)

For the production of 1 kg uranium from seawater about 109 kg seawater - depending on the extraction efficiency - have to be processed in a production plant. Such high seawater flows have to be put through adsorber beds the area of which depends on the flow velocity of the water in the bed. For a typical polyamidoxim (PAO) adsorber granulate with a grain size distribution of 0.3 to 1.2 mm the velocity in a fluidized bed is limited to about 1 cm/s in order to prevent carry out of the adsorber material. The consequences of this rather low bed velocity are large and expensive bed areas for technical production plants. The present paper deals with the so-called ''adsorber loop concept'' in which the adsorber granulate is carried along with the seawater to be processed in a loop-like configuration and is separated again from the water before this is leaving the adsorption unit. This concept enables considerably higher seawater velocities thus reducing the bed area. Theoretical considerations are presented together with experimental results from field tests. (author)

329

Breakdown products formed due to oxidation of adsorbed phenol by electrochemical regeneration of a graphite adsorbent  

International Nuclear Information System (INIS)

Phenol was studied as a model pollutant for treatment by adsorption and electrochemical regeneration using a graphite intercalation compound (GIC) adsorbent in an air agitated sequential batch reactor. The mechanism of electrochemical regeneration is important in determining the fate of the adsorbed species. The effect of a range of operating parameters including current density, pH, electrolyte addition, and the initial concentration of phenol on the formation of the intermediate oxidation products was investigated. The main breakdown products detected were benzoquinone and chlorinated organics (chloride was present as an electrolyte in the cathode compartment), with small amounts of hydroquinone, catechol, and carboxylic acids detected under some conditions. The effect of current density on the formation of breakdown products during electrochemical regeneration was found to be similar to effects reported in the literature for the electrochemical oxidation of a phenol solution. In contrast to acidic pH, very low concentrations of benzoquinone were observed during electrochemical regeneration of GIC adsorbent under neutral and alkaline conditions. The results obtained with high initial phenol concentration (100 mg L?1) suggested that breakdown products could be formed either by oxidation of adsorbed phenol or indirect oxidation of phenol in solution. Comparison of experiments carried out with different amounts of adsorbed and dissolved phenol suggested that the intermediate oxidation products obtained was formed largely due to indirect electrochemical oxidation of organics in solution. In particular, it was found that the chlorinated organics detected in solution were generated from the indirect oxidation of phenol in solution

330

Removal of adsorbent particles od copper ions by Jet flotation  

International Nuclear Information System (INIS)

The present study shows the results obtained on the removal of copper ions from synthetic effluents by using the adsorbent particles flotation technique (APF) in a Jet flotation cell (Jameson type). In a typical experimental run, a mineral with high quartz content was used as adsorbent particles in the adsorption and flotation experiments, to determine optimal pH conditions, adsorbent particles concentration; flotation reagents dosage and air/effluent flow ratio for applying in the Jet cell to maximize the efficiency of copper ions adsorptions and the removal of particles adsorbents containing the absorbed copper ions. The results indicate the at pH>7 and at adsorbent particles concentration of 2 kg.m-3, 99% of copper ions is adsorbed and, when the air/effluent flow ratio applied in the Jet cell is 0,2, 98% of absorbent particles containing the adsorbed copper ions is removed. (Author) 39 refs.

331

Endotoxin removal from water using microporous polyethylene chopped fibres as a new adsorbent.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A new adsorbent, microporous polyethylene chopped fibre, was produced from a high density polyethylene. This can adsorb lipopolysaccharides (LPS) linearly up to 2 h, and showed the highest capacity to adsorb LPS when compared with two other polyethylene-based adsorbents and a polystyrene-based adsorbent. More than twice as much orange II and 4-nitroquinoline N oxide were adsorbed in the new adsorbent as was LPS. The adsorption isotherm of the new adsorbent for LPS was of Ln type, the correlat...

Sawada, Y.; Fujii, R.; Igami, I.; Kawai, A.; Kamiki, T.; Niwa, M.

1986-01-01

332

Molecular factors in dendritic cell responses to adsorbed glycoconjugates.  

Science.gov (United States)

Carbohydrates and glycoconjugates have been shown to exert pro-inflammatory effects on the dendritic cells (DCs), supporting pathogen-induced innate immunity and antigen processing, as well as immunosuppressive effects in the tolerance to self-proteins. Additionally, the innate inflammatory response to implanted biomaterials has been hypothesized to be mediated by inflammatory cells interacting with adsorbed proteins, many of which are glycosylated. However, the molecular factors relevant for surface displayed glycoconjugate modulation of dendritic cell (DC) phenotype are unknown. Thus, in this study, a model system was developed to establish the role of glycan composition, density, and carrier cationization state on DC response. Thiol modified glycans were covalently bound to a model protein carrier, maleimide functionalized bovine serum albumin (BSA), and the number of glycans per BSA modulated. Additionally, the carrier isoelectric point was scaled from a pI of ?4.0 to ?10.0 using ethylenediamine (EDA). The DC response to the neoglycoconjugates adsorbed to wells of a 384-well plate was determined via a high throughput assay. The underlying trends in DC phenotype in relation to conjugate properties were elucidated via multivariate general linear models. It was found that glycoconjugates with more than 20 glycans per carrier had the greatest impact on the pro-inflammatory response from DCs, followed by conjugates having an isoelectric point above 9.5. Surfaces displaying terminal ?1-2 linked mannose structures were able to increase the inflammatory DC response to a greater extent than did any other terminal glycan structure. The results herein can be applied to inform the design of the next generation of combination products and biomaterials for use in future vaccines and implanted materials. PMID:24746228

Hotaling, Nathan A; Cummings, Richard D; Ratner, Daniel M; Babensee, Julia E

2014-07-01

333

Ion exchangers as adsorbents for removing metals from aquatic media.  

Science.gov (United States)

A polyaniline-based composite cation-exchange material was synthesized by way of sol-gel method and studied to explore its analytical and environmental applications. It was characterized by using instrumental analyses [Fourier transform infrared (spectrometer), X-ray, thermogravimetric analysis/differential thermal analysis, standard electron microscopy, and transmission electron microscopy]. Physicochemical studies, such as ion-exchange capacity, pH titrations, and chemical stability, along with effect of eluent concentration and elution, were also performed to exploit the ion-exchange capabilities. pH titration studies showed that the material presents monofunctional strong cation-exchange behavior. This nanocomposite material is semicrystalline in nature and exhibits improved thermal and chemical stability. The partition coefficient studies of different metal ions in the material were performed in demineralised water and different surfactant media, and it was found to be selective for Pb(II) and Hg(II) ions. To exploit the usefulness of the material as an adsorbent, some important quantitative binary separations of metal ions were performed on polyaniline Zr(IV) molybdophosphate columns. This composite cation exchanger can be applied for the treatment of polluted water to remove heavy metals. PMID:24292693

Khan, Meraj A; Bushra, Rani; Ahmad, Anees; Nabi, Syed A; Khan, Dilwar A; Akhtar, Arshia

2014-02-01

334

Detecting Adsorbed Sulfate and Phosphate on Nanophase Weathering Products on Mars  

Science.gov (United States)

Characterizing the mineralogy and chemistry of aqueous alteration phases on the martian surface is essential for understanding past aqueous processes because the types of secondary phases present and their chemical compositions tell us about the environments in which they formed. Orbital mid-infrared data and in-situ mineralogical and chemical data from the martian surface indicate that Si/Al- and Fe-bearing nanophase weathering products are widespread, including allophane and nanophase ferric oxide (npOx), which includes any combination of superparamagnetic hematite and goethite, ferrihydrite, schwertmannite, akaganeite, iddingsite, and palagonite (altered basaltic glass) [Morris et al., 2006; Michalski et al., 2006; Rampe et al., in press]. These weathering products have larger surface areas and variable surface charge and can adsorb anions and cations onto their surfaces. Some anions, such as sulfate and phosphate, specifically chemically adsorb onto mineral/mineraloid surfaces so that these complexes are covalently bonded and form ligands. Nanophase weathering products on Earth can specifically adsorb up to a few weight percent to a few tens of weight percent phosphate and sulfate, respectively [Parfitt and Smart, 1978; Jara et al., 2006]. Phosphate and sulfate have been identified in martian rocks and soils in abundances of up to ~5 wt.% and ~30 wt.%, respectively [Gellert et al., 2006; Ming et al., 2006], and it has been suggested that phosphate and sulfate ions may be adsorbed on nanophase weathering products on the martian surface [Greenwood and Blake, 2006; Morris et al., 2006]. What is relatively unknown is how to use in-situ and orbital instruments on Mars to determine if these ions are present as discrete minerals or adsorbed onto the surfaces of weathering products. We adsorbed phosphate and sulfate onto allophane surfaces in the laboratory. Here, we present laboratory measurements of phosphate- and sulfate-adsorbed allophane to compare to in-situ observations from CheMin and SAM on Mars Science Laboratory and remote observations from OMEGA, CRISM, and TES. CheMin- and OMEGA/CRISM-relevant laboratory measurements reveal minor differences between ion-free and ion-adsorbed allophane that would not be detectable by those instruments. However, SAM-relevant evolved gas analyses of sulfate-adsorbed allophane show a high-temperature (>950 C) release related to SO2 gas. The release at high temperatures suggests that sulfate was strongly bonded to the allophane surface. TES-relevant thermal-infrared emission spectra of phosphate- and sulfate-adsorbed allophane display broad absorptions near 1000 cm-1 from P-O and S-O vibrations. Our laboratory measurements suggest that ions adsorbed onto weathering product surfaces may be recognized on Mars with in-situ measurements by SAM on MSL and with orbital measurements from TES. Future experiments will include similar laboratory measurements of phosphate- and sulfate-adsorbed nanophase ferric oxides.

Rampe, E. B.; Morris, R. V.

2012-12-01

335

Modeling adsorption properties on the basis of microscopic, molecular, and structural descriptors for nonpolar adsorbents.  

Science.gov (United States)

We propose a method for analytically predicting single-component adsorption isotherms from molecular, microscopic and structural descriptors of the adsorbate-adsorbent system and concepts of statistical thermodynamics. Expressions for Henry's constant and the heat of adsorption at zero coverage are derived. These functions depend on the pore size, pore shape, chemical composition, and density of the adsorbent material. They quantify the strength of the solid-fluid interaction, which governs the low-pressure part of the adsorption isotherm. For intermediate and high pressures, the fluid-fluid interactions must also be taken into account. Both solid-fluid and fluid-fluid interactions are combined within the framework of the Ruthven statistical model (RSM). The RSM thus constructs theoretical adsorption isotherms that are entirely based on microscopic molecular and structural descriptors. The theoretical results that we obtained are compared with experimental data for the adsorption of pure CO2 and CH4 on all-silica zeolites. The developed methodology allows for the estimation of the optimum properties of a nonpolar adsorbent for the adsorption of CO2 in cyclic adsorption processes. PMID:23805808

García, Edder J; Pérez-Pellitero, Javier; Jallut, Christian; Pirngruber, Gerhard D

2013-07-30

336

Tailoring fly ash activated with bentonite as adsorbent for complex wastewater treatment  

Science.gov (United States)

Used as adsorbent, alkali fly ash represents a low cost solution for advanced wastewater treatment. The alkali treatment raises sustainability issues therefore, in this research we aim to replace alkali fly ash with washed fly ash (FAw). For improving the adsorption capacity of washed fly ash, bentonite powder (B) was added, as a natural adsorbent with a composition almost identical to the fly ash. The new adsorbent was characterized by AFM, XRD, FTIR, SEM, EDS and the surface energy was evaluated by contact angle measurements. For understanding the complex adsorption process on this mixed substrate, preliminary tests were developed on synthetic wastewaters containing a single pollutant system (heavy metal), binary (two-heavy metals) and ternary (dye and two heavy metals) systems. Experiments were done on synthetic wastewaters containing methylene blue, cadmium and copper, using FAw, B and their powder mixtures. The pseudo-second order kinetics could well model all the processes, indicating a good adsorbent material which can be used for the pollutants removal from wastewater. After adsorption the substrates loaded with pollutants, annealed at 500 °C can be reused for padding in stone blocks.

Visa, Maria

2012-12-01

337

Heat capacity measurements of atoms and molecules adsorbed on evaporated metal films  

International Nuclear Information System (INIS)

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 4He adsorbed on metallic films. In contrast to measurements of 4He adsorbed on all other insulating substrates, we have shown that 4He 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, 4He adsorbed on sapphire and on Ag films and H2 adsorbed on Ag films. The results are compared with appropriate theories. 68 refs., 19 figs

338

Comparison of Lead Removal by Various Types of Swine Bone Adsorbents  

Directory of Open Access Journals (Sweden)

Full Text Available The removal capacities of lead by bone adsorbents, prepared in various appropriate types, have been studied in a single component system using agitated batch sorption. The adsorbent characteristics before and after sorption were examined by electron microscopy, surface area analysis (BET, crystalline structure by x-ray diffractometer (XRD, chemical compositions by x-ray fluorescence (XRF and by Fourier transform infrared (FT-IR. The results showed that the main component of swine bone adsorbents is calcium hydroxyl¬apatite with Ca/P ratio is 1.70; the calcium ion and the range of mesopores of the appropriate pore sizes are the important factors for the ion-exchange process and the sorption process. The effects of carbonization, activation, initial metal ion solution concentration, contact time and quantities of bone adsorbent mass were studied. The capacity removal of lead onto bone powder, bone char and activated bone char were 417, 1828 and 690 mg/g, respectively, for 10 mg/L and pH 5±0.1 of the initial lead ion solution concentration, with an agitation speed 175 rpm. The sorption isotherm was also studied and indicated that the Langmuir isotherm model closely fits the sorbtion of lead onto bone char.

Sudaratn Lurtwitayapont

2010-01-01

339

A novel magnetic 4A zeolite adsorbent synthesised from kaolinite type pyrite cinder (KTPC)  

Science.gov (United States)

As a solid waste, kaolinite type pyrite cinder (KTPC) is a special pyrite cinder, its mineral components include metakaolin and magnetite, and the chemical compositions of these minerals include SiO2, Al2O3, FeO and Fe2O3. In this study, a novel magnetic 4A zeolite adsorbent was synthesised from KTPC using the hydrothermal method, and the optimum hydrothermal synthesis conditions were investigated using X-ray diffraction (XRD) and by determining the specific surface area (SSA) and the saturated cation exchange adsorption capacity (SCEAC) to Cs+. Under the optimum hydrothermal synthesis conditions, the magnetic 4A zeolite adsorbent can be synthesised with high crystallinity, and the SSA and SCEAC to Cs+ are 24.49 m2/g and 106.63 mg/g, respectively. The further characterisations of pore size distribution, scanning electron microscopy (SEM), energy dispersive X-ray (EDX), thermogravimetry-derivative thermogravimetry-differential thermal analysis (TG-DTG-DTA), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM) were performed. The results revealed that magnetic particles are coated onto the zeolite surface and further form magnetic aggregates, and the existing magnetic particles in KTPC do not change their crystal structure and do not affect the synthesis of the 4A zeolite. In addition, the synthesised 4A zeolite adsorbent can be used as a magnetic adsorbent in wastewater treatment with high magnetic sensitivity and is thermally stable up to approximately 900 °C.

Wang, Weiqing; Feng, Qiming; Liu, Kun; Zhang, Guofan; Liu, Jing; Huang, Yang

2015-01-01

340

A transient performance method for CO2 removal with regenerable adsorbents  

Science.gov (United States)

A computer program is described which can be used to predict the transient performance of vacuum-desorbed sorbent beds for CO2 or water removal, and composite beds of two sorbents for simultaneous humidity control and CO2 removal. The program was written primarily for silica gel and molecular sieve inorganic sorbents, but can be used for a variety of adsorbent materials. Part 2 of this report describes a computer program which can be used to predict performance for multiple-bed CO2-removal sorbent systems. This program is an expanded version of the composite sorbent bed program described in Part 1.

Hwang, K. C.

1972-01-01

 
 
 
 
341

Synthesis of Nanocomposite Adsorbent on the Base of Polypropylene Fabric with Copper Ferrocyanide Grains  

Directory of Open Access Journals (Sweden)

Full Text Available Composite adsorbents based on polypropylene fibers with chemically bound nanopartices of copper ferrocyanide were synthesized by two-stage experiment: radiation-induced graft polymerization of acrylic acid onto non-woven polypropylene fabric followed by in-situ formation of copper ferrocyanize nanoparticles and their stabilization on the fabric surface within the grafted layer. Scanning electron microscope investigations revealed a homogeneous compact layer of copper ferrocynide nanosized aggregates (65-70 nm. The synthesized composite material was stable in the base solutions (pH ? 10.5 and exhibited high efficiency for cesium adsorption.

Bondar I.V.

2012-08-01

342

Adsorption characteristics of water vapor on honeycomb adsorbents  

International Nuclear Information System (INIS)

Recovery of tritium released into working areas in nuclear fusion plants is a key issue of safety. A large volume of air from tritium fuel cycle or vacuum vessel should be processed by air cleanup system (ACS). In ACS, tritium gas is oxidized by catalysts, and then tritiated water vapor is collected by adsorbents. This method can remove tritium effectively, whereas high throughput of air causes high-pressure drop in catalyst and adsorbent beds. In this study, the applicability of honeycomb-type adsorbents, which offers a useful advantage in terms of their low-pressure drop, to ACS was examined, in comparison with conventional pebble-type adsorbent. Honeycomb-type adsorbent causes far less pressure drop than pebble-type adsorbent beds. Adsorption capacity of water vapor on a honeycomb-type adsorbent is slightly lower than that on a pebble-type adsorbent, while adsorption rate of water vapor on honeycomb-type adsorbent is much higher than that of pebble-type adsorbent.

343

?-radiolysis of methane adsorbed on ?-alumina  

International Nuclear Information System (INIS)

Previous studies showed that methane adsorbed on ?-alumina undergoes radiolysis to form chemisorbed precursor species. These decompose when heated to give C1-C3 alkane and alkene products together with hydrogen. The present study uses nitric oxide, nitrous oxide, sulphur hexafluoride, oxygen and carbon dioxide as additives to interfere with product formation, and so allows probable structures to be deduced for each precursor. Both alkane and alkene precursors involve alkylaluminium groups which decompose by homolytic fission of the Al-C bond. The alkane precursor has an accessible hydroxide ion from which a hydrogen atom can be extracted during desorption, whereas the alkene precursor does not. (author)

344

Spectroscopy and dynamics of orientationally structured adsorbates  

CERN Document Server

This book provides a detailed and rigorous presentation of the spectroscopy and dynamics of orientationally structured adsorbates. It is intended largely for specialists and graduate students in solid state theory and surface physics. To make the book readable also for beginners in surface science, a lucid style is used and a wealth of references on orientational surface structures and vibrational excitations in them is offered. The book is supplemented with two indices (alphabetical listing of subjects and authors, as well as cross-references) which will enable the reader to easily access the

Rozenbaum, V M

2002-01-01

345

Stability constants for silicate adsorbed to ferrihydrite  

DEFF Research Database (Denmark)

Intrinsic surface acidity constants (K(a1)intr, K(a2)intr) and surface complexation constant for adsorption of orthosilicate onto synthetic ferrihydrite (K(Si) for the complex = FeOSi(OH)3) have been determined from acid/base titrations in 0.001-0.1 m NaClO4 electrolytes and silicate adsorption experiments in 0.01 m NaNO3 electrolyte (pH 3-6). The surface equilibrium constants were calculated according to the two-layer model by Dzombak & Morel (1990). Near equilibrium between protons/hydroxyls in solution and the ferrihydrite surface was obtained within minutes while equilibration with silicate required days-weeks, both reactions probably being diffusion controlled. Applying the values for specific surface area and site densities for ferrihydrite used by Dzombak & Morel (1990) (600 m2 g-1, 3.4 mumole m-2) the constants pK(al)intr 6.93 +/- 0.12, pK(a2)intr = 8.72 +/- 0.17 and log K(Si) = 3.62 were calculated by using the FITEQL optimization routine. Use of the specific surface area actually measured (269 m2 g-1) gave a poorer fit of the experimental data. Due to the slow adsorption of silicate and hence long shaking times, changes in the surface characteristics of the ferrihydrite seem to take place, probably a decrease in the concentration of surface sites. Adsorption isotherms calculated using the derived equilibrium constants showed that approximately twice the amount of silicate was adsorbed at pH 5 compared with pH 3. Infrared spectroscopy of silica adsorbed to ferrihydrite showed Si-O stretching absorption maxima in the range 940-960 cm- 1. The shift of the absorption maximum to higher wavenumbers with increasing amount of silicate adsorbed is probably due to an increase in the frequency of Si-O-Si bonds between orthosilicate adsorbed at adjacent sites. Small amounts of goethite were identified in the adsorption products.

Hansen, Hans Christian Bruun; Wetche, T.P.

1994-01-01

346

Analysis of samples of reflector materials which are multicoated and metal samples with oxide coatings which have been exposed the space environment in LDEF testing  

Science.gov (United States)

The use of low angle x-ray diffraction (XRD), x-ray photoelectron spectrometry (XPS), and Auger spectrometry have been tested as suitable methods for analysis of thin oxide films on metal substrates exposed to the space environment during Long Duration Exposure Facility (LDEF) testing. No significant changes in the composition of silicon monoxide overcoats on aluminum surfaces was found. XPS and Auger testing appear to be more suitable for ultrathin films than XRD.

Neely, W. C.

1992-01-01

347

New type of amidoxime-group-containing adsorbent for the recovery of uranium from seawater. III. Recycle use of adsorbent  

International Nuclear Information System (INIS)

An amidoxime-group adsorbent for recovering uranium from seawater was made by radiation-induced graft polymerization of acrylonitrile onto polymeric fiber, followed by amidoximation. Uranium adsorption of the adsorbent contacted with seawater in a column increased with the increase in flow rate, then leveled off. The relationship between uranium adsorption in a batch process and the ratio of the amount of seawater to that of adsorbent was found to be effective in evaluating adsorbent contacted with any amount of seawater. The conditioning of the adsorbent with an alkaline solution at higher temperature (?800C) after the acid desorption recovered the adsorption ability to the original level. This made it possible to apply the adsorbent to recycle use. On the other hand, the adsorbent conditioned at room temperature or that without conditioning lost adsorption ability during recycle use. The increase in water uptake was observed as one of the physical changes produced during recycle use of the alkaline-conditioned adsorbent, while the decrease in water uptake was observed with the unconditioned adsorbent. The IR spectra of the adsorbent showed a probability of reactions of amidoxime groups with acid and alkaline solutions, which can explain the change in uranium adsorption during the adsorption-desorption cycle

348

TRMM project contamination control using molecular adsorbers  

Science.gov (United States)

The Tropical Rainfall Measuring Mission (TRMM) is a spacecraft under development by the National Aeronautics and Space Administration (NASA) and the National Space Development Agency of Japan (NASDA) and is scheduled for launch in August 1997. The spacecraft design includes the use of numerous optical instruments and the thermal control surfaces. In addition to the inherent contamination sensitivities of the optical and thermal systems, TRMM has had the added challenge of designing systems to function at a relatively low altitude (350 km), with solar exposure. Under these conditions, high atomic oxygen densities and potentially high levels of backscattered contamination (self-contamination), as well as UV photopolymerization effects, all pose major threats to sensitive TRMM elements. In considering the various contamination control paths to follow, the TRMM project management has opted for pursuing a relatively new, but very promising technology for the TRMM spacecraft in order to lower the on-orbit contamination levels. TRMM will be incorporating Molecular Adsorbers as part of the basic spacecraft design. This paper will summarize the TRMM requirements, describe the Molecular Adsorbers being fabricated for the mission, and discuss the expected benefits of this method of on-orbit contamination control.

Straka, Sharon; Chen, Philip; Thomson, Shaun; Bettini, Ron; Triolo, Jack; Carosso, Nancy

1996-03-01

349

Hexavalent chromium removal using indigenously developed adsorbents  

International Nuclear Information System (INIS)

Present study is based on the usage of natural waste material i.e. two types of tree leaves (ficus Religiosa and Pongamia Pinnata) for the adsorption of Cr(VI). Hexavalent chromium removal efficiency of developed sorbents is determined experimentally. Effect of different variables like shaking time, shaking speed, initial metal ion concentration, adsorbent dose, pH, and of temperature was studied. Both adsorbents showed almost complete chromium removal at pH value of 2.0 and adsorption is shown to be endothermic in nature for pongamia pinnata leaves. Optimum values obtained in this study are, pH 2.0, shaking speed 200 rpm, shaking time 45 minutes, temperature of 50 degree C. Adsorption capacities obtained at optimum conditions are 17.5 and 15.7 mg/g for ficus religiosa and Pongamia Pinnata leaves respectively. Adsorption data follow Langmuir model. Predominant adsorption phenomenon on leaves seems to be surface adsorption but other binding mechanism like ion exchange may also be a contributing factor. (author)

350

SOx on ceria from adsorbed SO2  

Science.gov (United States)

Results from first-principles calculations present a rather clear picture of the interaction of SO2 with unreduced and partially reduced (111) and (110) surfaces of ceria. The Ce3+/Ce4+ redox couple, together with many oxidation states of S, give rise to a multitude of SOx species, with oxidation states from +III to +VI. SO2 adsorbs either as a molecule or attaches via its S-atom to one or two surface oxygens to form sulfite (SO32-) and sulfate (SO42-) species, forming new S-O bonds but never any S-Ce bonds. Molecular adsorption is found on the (111) surface. SO32- structures are found on both the (111) and (110) surfaces of both stoichiometric and partially reduced ceria. SO42- structures are observed on the (110) surface together with the formation of two reduced Ce3+ surface cations. SO2 can also partially heal the ceria oxygen vacancies by weakening a S-O bond, when significant electron transfer from the surface (Ce4f) into the lowest unoccupied molecular orbital of the SO2 adsorbate takes place and oxidizes the surface Ce3+ cations. Furthermore, we propose a mechanism that could lead to monodentate sulfate formation at the (111) surface.

Lu, Zhansheng; Müller, Carsten; Yang, Zongxian; Hermansson, Kersti; Kullgren, Jolla

2011-05-01

351

Single Molecule Experiments with Adsorbed Polyelectrolytes  

Science.gov (United States)

We report on the AFM study of single polyelectrolyte (positively charged) molecules (PE) adsorbed on mica surfaces at different conditions (we vary pH and salt concentration). The study was carried out under aqueous solutions in a liquid cell. We observed behavior of PE in real time. The AFM experiments were experiments when possible effects of the AFM tip on PE conformations were minimized. A series of experiments were carried out when PE was adsorbed between two electrodes at applied electrical potential. The AFM images were processed to extract contour length, end-to-end distance, and radii of center of mass. The experiments revealed several interesting facts about adsorption of PE. The chain statistics was found to be consistent with the 2D random walk model. A decrease of charge density resulted in the coil-to-globule transition. The globules appear as a strongly deformed swollen polymer globule. In saline solutions the globules resemble necklace-like globules. PE chains were mobile if an electrical field was applied. The motion of PE chains can be describes as a caterpillar-like motion.

Minko, Sergiy; Roiter, Yuri

2006-03-01

352

[Nisin sorption and desorption on different silica adsorbents].  

Science.gov (United States)

Nisin sorption on some silica adsorbents in columns was studied. Silica gels, silochromes and sintered glass with various pore diameters, various specific surfaces, etc. were tested. Correlation between the adsorbent adsorption capacity with respect to nisin and the adsorbent pore diameter was observed. The tested silochromes, silica gels with the pore diameters of 70-80 nm and sintered glass with the pore diameters of 65-112 nm had the highest adsorption capacity with respect to nisin. PMID:2820297

Baranova, I P; Egorov, N S; Grushina, V A

1987-06-01

353

Role of structure and glycosylation of adsorbed protein films in biolubrication.  

Science.gov (United States)

Water forms the basis of lubrication in the human body, but is unable to provide sufficient lubrication without additives. The importance of biolubrication becomes evident upon aging and disease, particularly under conditions that affect secretion or composition of body fluids. Insufficient biolubrication, may impede proper speech, mastication and swallowing, underlie excessive friction and wear of articulating cartilage surfaces in hips and knees, cause vaginal dryness, and result in dry, irritated eyes. Currently, our understanding of biolubrication is insufficient to design effective therapeutics to restore biolubrication. Aim of this study was to establish the role of structure and glycosylation of adsorbed protein films in biolubrication, taking the oral cavity as a model and making use of its dynamics with daily perturbations due to different glandular secretions, speech, drinking and eating, and tooth brushing. Using different surface analytical techniques (a quartz crystal microbalance with dissipation monitoring, colloidal probe atomic force microscopy, contact angle measurements and X-ray photo-electron spectroscopy), we demonstrated that adsorbed salivary conditioning films in vitro are more lubricious when their hydrophilicity and degree of glycosylation increase, meanwhile decreasing their structural softness. High-molecular-weight, glycosylated proteins adsorbing in loops and trains, are described as necessary scaffolds impeding removal of water during loading of articulating surfaces. Comparing in vitro and in vivo water contact angles measured intra-orally, these findings were extrapolated to the in vivo situation. Accordingly, lubricating properties of teeth, as perceived in 20 volunteers comprising of equal numbers of male and female subjects, could be related with structural softness and glycosylation of adsorbed protein films on tooth surfaces. Summarizing, biolubrication is due to a combination of structure and glycosylation of adsorbed protein films, providing an important clue to design effective therapeutics to restore biolubrication in patients with insufficient biolubrication. PMID:22916138

Veeregowda, Deepak H; Busscher, Henk J; Vissink, Arjan; Jager, Derk-Jan; Sharma, Prashant K; van der Mei, Henny C

2012-01-01

354

WGS-Adsorbent Reaction Studies at Laboratory Scale  

International Nuclear Information System (INIS)

This document reports the most significant results obtained during the experimental work performed under task WGS adsorbent experimental studies within CAPHIGAS project (National Research Plan 2008-2011, ref: ENE2009-08002). The behavior of the binary adsorbent-catalyst system which will be used in the hybrid system is described in this document. Main results reported here were used during the design and development of the hybrid system adsorbent catalyst- membrane proposed in the CAPHIGAS project. The influence of main operating parameters and the optimized volume ratio adsorbent-catalyst are also presented in this report. (Author)

355

Structural characterization and thermal analysis of 4 A and 5 A zeolite adsorbents  

International Nuclear Information System (INIS)

Adsorption processes are widely used in the industries, both for purification and for bulk separation. The discovery and commercialization of synthetic zeolites as adsorption provide a major stimulus to the development of adsorption as a separation process. The primary requirement for development of an adsorption separation process using zeolite is the structural characterization of the material. The most important analysis include the evaluation of pore volume, pore size distribution, surface area and density. This paper describes commercial zeolitic adsorbents, its structure and the methods applied to its characterization. They work also an experimental study where different analytical techniques were used to determine the physical properties, chemical composition and crystalline structure for type 4A zeolitic adsorbents. (author)

356

Neutron Reflection Study of Bovine ?-Casein Adsorbed on OTS Self- Assembled Monolayers  

Science.gov (United States)

Specular neutron reflection has been used to determine the structure and composition of bovine ?-casein adsorbed on a solid surface from an aqueous phosphate-buffered solution at pH 7. The protein was adsorbed on a hydrophobic monolayer self-assembled from deuterated octadecyltrichlorosilane solution on a silicon (111) surface. A two-layer structure formed consisting of one dense layer of thickness 23 ± 1 angstroms and a surface coverage of 1.9 milligrams per square meter adjacent to the surface and an external layer protruding into the solution of thickness 35 ± 1 angstroms and 12 percent protein volume fraction. The structure of the (?-casein) layer is explained in terms of the charge distribution in the protein.

Fragneto, Giovanna; Thomas, Robert K.; Rennie, Adrian R.; Penfold, Jeffrey

1995-02-01

357

Molecular insights into the selective action of a magnetically removable complexone-grafted adsorbent.  

Science.gov (United States)

The binding and release of trivalent rare earth element (REE) cations (Dy(3+), Nd(3+) and La(3+)) from solutions by a new fully characterized magnetic nano adsorbent material, consisting of iminodiacetic acid ligand (H2IDA) grafted onto SiO2 covered ?-Fe2O3 nanoparticles, was investigated. The nano adsorbent revealed a slightly higher capacity towards heavier REE and appreciable selectivity, especially on desorption. It was found that the composition of the surface complex was RE(3+)?:?L = 1?:?1. The complexation of the molecular H2IDA with RE(3+) in this ratio under non-basic conditions was therefore investigated by X-ray crystallography to produce relevant molecular models. Unexpectedly big differences in coordination numbers and binding mode of IDA along with distinct analogies in packing of the ligand molecules in the obtained 2D-coordination polymer structures provided valuable insights into possible reasons for the observed selectivity. PMID:25415854

Polido Legaria, Elizabeth; Topel, Seda Demirel; Kessler, Vadim G; Seisenbaeva, Gulaim A

2015-01-21

358

Resilience of gas-phase anharmonicity in the vibrational response of adsorbed carbon monoxide and breakdown under electrical conditions  

CERN Document Server

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...

Dabo, Ismaila

2012-01-01

359

NOx Removal and Effect of Adsorbate-Adsorbate Interactions  

DEFF Research Database (Denmark)

Heterogeneous catalysis is immensely important to modern and future society. It forms the foundation of chemical industry, supplying essential chemicals and commodities for transport, food production, and pharmaceuticals, and is also a cornerstone in current and future energy platforms. If the long-standing dream of an environmentally sustainable energy sector is to be fulfilled, heterogeneous catalysts aiding production, storage, and use of energy from sustainable sources, e.g. sunlight, wind, and biomass, are expected to be essential. New catalysts improving the efficiency of existing chemical processes, such as ammonia synthesis and sulphur removal in refining, may also contribute to improving future society at large. However, developing the catalysts of tomorrow presents a wealth of scientific challenges. Understanding surface science has always been essential for development and improvement of industrial chemical processes, nano-science and nano-technology, in general any process where a solid surface interacts with any surrounding liquid or gas-phase species. Computational approaches play an increasingly important role in modern surface science, and density functional theory (DFT) in particular. Indeed, several recent developments in our understanding of important aspects of heterogeneous catalysis derive from electronic structure calculations based on DFT. However, there are still many challenges and lots of scope for improvement in the density functional approach to surface science. To mention a few, to improve the accuracy of electronic structure calculations, accuracy of the physical model, completeness of kinetic models for chemical reactions, figuring out the exact state of catalysts under reaction conditions, and also reducing the complexity of our physical models. In this thesis I have analyzed these challenges systematically and have developed some new methods and models to counter those challenges and obtain some general understanding of the catalytic process. I have developed an adsorbate-adsorbate interaction model to include the coverage dependency of the adsorption energy in kinetic models to obtain more accurate catalytic rates than with the commonly used non-interacting mean field model. I then applied the proposed adsorbate-adsorbate interaction model to three important catalytic reactions, the direct NO decomposition, CO methanation, and steam reforming of methane, and analyzed the effect of adsorbate-adsorbate interactions on their catalytic rates. An alloy screening method has also been developed to screen for the industrially most promising alloy catalysts for any catalytic reaction. I have also studied the structure sensitivity of the rates of catalytic direct NO decomposition on different low-index metal surfaces. Furthermore, I have used DFT calculated adsorption and transition state energies coupled with a microkinetic model to study two industrially important catalytic reactions, NH3 oxidation and selective catalytic reduction of NOx, to obtain the catalytic trends and understand the reaction mechanisms.

Khan, Tuhin Suvra

2013-01-01

360

Milestone Report - Complete New Adsorbent Materials for Marine Testing to Demonstrate 4.5 g-U/kg Adsorbent  

Energy Technology Data Exchange (ETDEWEB)

This report describes work on the successful completion of Milestone M2FT-14OR03100115 (8/20/2014) entitled, “Complete new adsorbent materials for marine testing to demonstrate 4.5 g-U/kg adsorbent”. This effort is part of the Seawater Uranium Recovery Program, sponsored by the U.S. Department of Energy, Office of Nuclear Energy, and involved the development of new adsorbent materials at the Oak Ridge National Laboratory (ORNL) and marine testing at the Pacific Northwest National Laboratory (PNNL). ORNL has recently developed two new families of fiber adsorbents that have demonstrated uranium adsorption capacities greater than 4.5 g-U/kg adsorbent after marine testing at PNNL. One adsorbent was synthesized by radiation-induced graft polymerization of itaconic acid and acrylonitrile onto high surface area polyethylene fibers followed by amidoximation and base conditioning. This fiber showed a capacity of 4.6 g-U/kg adsorbent in marine testing at PNNL. The second adsorbent was prepared by atom-transfer radical polymerization of t-butyl acrylate and acrylonitrile onto halide-functionalized round fibers followed by amidoximation and base hydrolysis. This fiber demonstrated uranium adsorption capacity of 5.4 g-U/kg adsorbent in marine testing at PNNL.

Janke, Christopher James [ORNL; Das, Sadananda [ORNL; Oyola, Yatsandra [ORNL; Mayes, Richard T. [ORNL; Saito, Tomonori [ORNL; Brown, Suree [ORNL; Gill, Gary [PNNL; Kuo, Li-Jung [PNNL; Wood, Jordana [PNNL

2014-08-01

 
 
 
 
361

Thermodynamic study of fatty acids adsorption on different adsorbents  

International Nuclear Information System (INIS)

This work has as objective the study about the adsorption behavior of fatty acids (acetic, propionic, and butyric) on activated carbon and on modified and unmodified montmorillonite clays as a function of temperature and initial concentration of the adsorbate, through adsorption isotherms and their thermodynamic parameters (?G, ?H, and ?S). The activated carbon presented a higher adsorption capacity due to its relatively large surface area, compared to others adsorbents. The polar characteristic of fatty acids decreased with the increase in the length of non-polar hydrocarbon chain, improving the affinity between the activated carbon (non-polar adsorbent) and the acids. The adsorption capacity of modified montmorillonite (polar adsorbent) was favored due to the presence of the organic cation among its layers, which make the surface more hydrophobic and organophilic when compared to the unmodified montmorillonite surface. The amount of fatty acids adsorbed in the adsorbents surface increased with the concentration, at constant temperature, and decreased with the increase of temperature, at constant concentration. The amount of fatty acids adsorbed in the three adsorbents was related to the surface area and polarity of the adsorbent, concentration and solubility of the adsorbate and temperature of the solution. The negative values of ?G and ?H showed that the adsorption on activated carbon and on modified and unmodified montmorillonite clays was a spontaneous and allonite clays was a spontaneous and an exothermic process. The decrease in the values of ?G, with the increase of temperature, demonstrated that the adsorption was benefited by the high temperature and the positive values of ?S showed that the fatty acids molecules were in a more randomic condition in the adsorbed state than in solution. The experimental results obtained at the temperatures of (298, 303, 313, and 323) K showed that experimental data were well represented by the Langmuir and Freundlich isotherms models

362

TIDES-ACS Trial: comparison of titanium-nitride-oxide coated bio-active-stent to the drug (everolimus)-eluting stent in acute coronary syndrome. Study design and objectives.  

Science.gov (United States)

Drug-eluting stents (DES), delivering antiproliferative drugs from a durable polymer, have shown to reduce in-stent restenosis after percutaneous coronary intervention (PCI) compared to bare-metal stents (BMS). However, they have been associated with a hypersensitivity reaction, delayed healing, and incomplete endothelialization, which may contribute to an increased risk of late stent thrombosis. Consequently, a prolonged duration of dual antiplatelet therapy (DAPT) is needed, with an increased risk of bleeding complication. A number of stent technologies are being developed in an attempt to modify late thrombotic events and DAPT duration. The Optimax™ stent is such a novel, next generation bioactive stent (BAS), in which a thicker layer of titanium-nitride-oxide coating is inserted over the stent struts. The rationale of this is to obtain more efficient and rapid vascular healing at the site of the stent implantation. The aim of TIDES-ACS Trial is to compare clinical outcome in patients presenting with ACS, treated with PCI using Optimax-BAS versus Synergy™-EES. Second objective is to explore whether the Optimax™-BAS use is superior compared with Synergy™-EES use with respect of hard end points (cardiac death, myocardial infarction [MI] and major bleeding). A prospective, randomized, multicenter trial (ClinicalTrials.gov Identifier: NCT02049229), will be conducted in interventional centres in Finland (six centres), France (five centres) and Holland (two centres), including a total of 1800 patients. PMID:25670057

Colkesen, E B; Eefting, F D; Rensing, B J; Suttorp, M J; Ten Berg, J M; Karjalainen, P P; Van Der Heyden, J A

2015-02-01

363

Utilization of Waste Eggshells as Humidity Adsorbent  

Directory of Open Access Journals (Sweden)

Full Text Available The chicken and duck eggshell powders were prepared and heated at 1300C for 4 h. The samples were analyzed by X-Ray Diffraction (XRD. It was found that Calcium Carbonate (CaCO3 from chicken and duck eggshells completely transformed into Calcium Oxide (CaO. Then the samples were placed in a box installed with a hygro-thermometer for humidity adsorption test in the range of 20-75% RH at 25C. Hydration rate for duck and chicken eggshells were 0.0625% RH min-1 (within 880 min and 0.0482% RH min-1 (within 1140 min respectively. The results show that CaO from the duck eggshells is a better adsorbent than that of chicken eggshells. Furthermore, after humidity adsorption, CaO obtained from both eggshells were partly transformed into portlandite (Ca(OH2 was confirmed by the Rietveld refinement method and Scanning Electron Microscope (SEM.

S. Limsuwan

2011-01-01

364

Ion exchange/adsorbent pilot plant  

International Nuclear Information System (INIS)

A decontamination of greater than 99% of the actinides and fission products contained in radioactive waste water can be obtained using ion exchange resins. A system for achieving this result is described in this paper. This ion exchange pilot-plant design is the culmination of five years of study of the decontamination of radioactive waste streams by ion exchange resins and other adsorbents at Mound. In order to maintain maximum flexibility of treatments, this pilot-plant design is a conceptual design with specific flows, resins, and column specifications, but with many optional features and no rigid equipment specifications. This flexibility allows the system to be amenable to almost any radioactive waste stream. Very specific designs can be constructed from this conceptual design for the treatment of any specific waste stream. Operating and capital costs are also discussed. 1 figure, 5 tables

365

Biodegradation of bacterial polysaccharides adsorbed on montmorillonite  

International Nuclear Information System (INIS)

In this research, by means of a model, a study was made of the biodegradation of microbial organic compounds adsorbed on clays, with a parallel experiment on Fontainebleau sand serving as the control. During incubation the three classes of organic matter (14C-labelled glucose, 14C-labelled polysaccharides and 14C-labelled microbial cells) mineralize more actively in the presence of sand than in the presence of clay, since the latter provides protection against biodegradation. Mineralization of the adsorbed organic compounds, however, is marked by clear-cut differences after three weeks - glucose (55%)>polysaccharides (43%)>microbial organisms (7.3%). After incubation, chemical extraction of the organo-mineral complexes by alkaline solvents shows only water-soluble and alkali-soluble products in the case of sand; conversely, in that of montmorillonite the bulk of the 14C was found in the non-extractable fraction or humin (18.1% of the initial 14C for glucose, 27.3% for the polysaccharides, and 67.6% for the microbial organisms). A second incubation carried out after a phase in which there was drying and remoistening of the organo-mineral complexes, brings to light the important part played by climatic alternations during the biodegradation process. A new mineralization phase is observed, affecting more the bacterial organisms (14.1%) than the polysaccharides (6.3%), with the glucose-base complexes occupying an intee glucose-base complexes occupying an intermediate position (11.2%). The chemical fractioning of the organo-mineral complexes following re-incubation shows the stability of 14C in humin very clearly, especially in the case of polysaccharides, where the mineralization phase relates primarily to the products extractable with alkalis. (author)

366

Effects of ambient conditions on adsorbed surfactant and polymer monolayers  

International Nuclear Information System (INIS)

The physical properties of surfactant-coated and polyelectrolyte-coated surfaces in adhesive contact in air have been studied using the surface forces apparatus technique. Various physisorbed monolayers with different head groups and chains (or polymer segments) were prepared both by adsorption form solution (self-assembly) and by the Langmuir-Blodgett deposition technique. The results show that many monolayer properties depend on the atmospheric conditions such as the relative humidity or presence of organic vapors and that these properties can further change when two monolayer-coated surfaces are brought into contact. These properties include monolayer composition and structure, thickness and compressibility, fluidity and phase state (i.e., whether solid, gel, or liquid), and the adhesion between two monolayer-coated surfaces. In addition, we find that both out-of-plane and in-plane (lateral) phase transitions can be induced in certain adsorbed monolayers when they are subjected to a compressive stress. The results provide new insights into molecular ordering and dynamics in physisorbed monolayers and how monolayers are affected when they are exposed to vapors or when they interact with other surfaces. 18 refs., 13 figs., 4 tabs

367

Removal of Acid Orange 7 from aqueous solution using magnetic graphene/chitosan: a promising nano-adsorbent.  

Science.gov (United States)

Magnetic graphene/chitosan (MGCh) nanocomposite was fabricated through a facile chemical route and its application as a new adsorbent for Acid Orange 7 (AO7) removal was also investigated. After synthesis, the full characterization with various techniques (FTIR, XRD, VSM, and SEM) was achieved revealing many possible interactions/forces of dye-composite system. The results showed that, benefiting from the surface property of graphene oxide, the abundant amino and hydroxyl functional groups of chitosan, and from the magnetic property of Fe3O4, the adsorbent possesses quite a good and versatile adsorption capacity to the dye under investigation, and can be easily and rapidly extracted from water by magnetic attraction. The maximum absorption capacity was reached at initial pH 3 and 120min contact time. The batch adsorption experiments showed that the adsorption of the AO7 is considerably dependent on pH of milieu, amount of adsorbent, and contact time. The adsorption kinetics and isotherms were investigated to indicate that the kinetic and equilibrium adsorption were well-described by pseudo-first order kinetic and Langmuir isotherm model, respectively. The adsorption behavior suggested that the adsorbent surface was homogeneous in nature. The study suggests that the MGCh is a promising nano adsorbent for removal of anionic azo dyes from aqueous solution. PMID:24813679

Sheshmani, Shabnam; Ashori, Alireza; Hasanzadeh, Saeed

2014-07-01

368

Distributions of uranium adsorbed from seawater in spherical polyacrylamidoxime chelating resins  

International Nuclear Information System (INIS)

Distributions of metals adsorbed from seawater in spherical polyacrylamidoxime chelating resins were measured by X-ray micro-analyzer. Distributions of uranium in adsorbents were different according to their gel structure or porosity. In the case of adsorbents with low swelling tendencies, uranium was adsorbed only in the superficial layers of the adsorbents. The amount of adsorbed uranium increased with increasing of contact time, but no uranium was detected in the center of adsorbent even after 331 days. Iron was adsorbed only in the surface layer. Magnesium was detected almost uniformly in all parts of adsorbent. Copper and zinc were detected very little. (author)

369

Synthesis of new adsorbents for Mo as an RI generator  

International Nuclear Information System (INIS)

Technetium-99m is widely used in the world for the purpose of diagnosis in nuclear medicine. The 99mTc is obtained from the parent nuclide of 99Mo adsorbed in a generator. Synthesis of Zr-based inorganic polymer, which has extremely high adsorbability of Mo and is applicable to the 99Mo product of low specific activity, was attempted. Five kinds of the precursors for Zr-based-polymer adsorbents were prepared by the hydrolysis of ZrCl4 and the reactions between ZrCl4 and poly (vinyl alcohol), isopropyl alcohol, ethylene glycol or glycerol. These precursors were converted into adsorbents by heating in Ar gas flow. Their structures were presumed from the pyrolysis behavior. Adsorption capacities of Mo of these adsorbents were dependent on the number of Cl atoms bonded to Zr atom in the molecules. It was suggested that the adsorption of Mo to these adsorbents was proceeded by chemical reaction between two neighboring Zr-Cl bonds and MoO42-. The adsorbent prepared from ZrCl4 and isopropyl alcohol showed the highest adsorption capacity of Mo (about 250 mg/g adsorbent) and 99mTc yield (about 80%) in eluant. (author)

370

Adsorbent Carbon Fabrics : New Generation Armour for Toxic Chemicals  

Directory of Open Access Journals (Sweden)

Full Text Available Activated carbon in the form of a regular fabric obtained using viscose rayon precursor is a new generation adsorbent material having superior sorptional properties and is finding varied defence applications. Carbonisation and activation mechanisms and properties and applications of adsorbent carbort fibres made from viscose rayon precursor are reviewed in this paper.

K. Gurudatt

2013-04-01

371

A nuclear standard high-efficiency adsorber for iodine  

International Nuclear Information System (INIS)

The structure of a nuclear standard high-efficiency adsorber, adsorbent and its performance are introduced. The performance and structure were compared with the same kind product of other firms. The results show that the leakage rate is less than 0.005%

372

Adsorption of uranium from dilute aqueous solution on inorganic adsorbents  

International Nuclear Information System (INIS)

The adsorption of uranium from a dilute aqueous solution by a large number of inorganic adsorbents has been investigated. A mixture of aluminum hydroxide, ferric hydroxide, and activated carbon in the weight ratio 1:3:4 has shown a high adsorbability for uranium. The separation of uranium from a dilute aqueous solution by this mixed adsorbent under various temperatures and pH values has been studied. The adsorbability was found to exhibit a maximum at pH 4.0 to 5.5 and to decrease with increasing temperature. A number of eluting solutions for the desorption of uranium from the mixed adsorbent were also tested; 1 N (NH4)2CO3 was found to be the most suitable eluting solution (93 percent recovery of uranium)

373

Flow boundary conditions for chain-end adsorbing polymer blends  

CERN Document Server

Using the phenol-terminated polycarbonate blend as an example, we demonstrate that the hydrodynamic boundary conditions for a flow of an adsorbing polymer melt are extremely sensitive to the structure of the epitaxial layer. Under shear, the adsorbed parts (chain ends) of the polymer melt move along the equipotential lines of the surface potential whereas the adsorbed additives serve as the surface defects. In response to the increase of the number of the adsorbed additives the surface layer becomes thinner and solidifies. This results in a gradual transition from the slip to the no-slip boundary condition for the melt flow, with a non-monotonic dependence of the slip length on the surface concentration of the adsorbed ends.

Zhou, X; Site, L D; Kremer, K

2005-01-01

374

Improvement of corrosion and biological properties of microarc oxidized coatings on Mg-Zn-Zr alloy by optimizing negative power density parameters.  

Science.gov (United States)

Corrosion and biological properties of microarc oxidized calcium phosphate (CaP) coatings on Mg-Zn-Zr alloy were improved by optimizing negative power density parameters. Scanning electron microscope (SEM) and X-ray diffractometer (XRD) were employed to characterize the coating morphology and phase composition. The in vitro cytotoxicity and systemic toxicity tests were carried out to evaluate the coating biocompatibility. The degradability and bioactivity of the coatings were determined by in vitro simulated body fluid (SBF) immersion test. The coating microstructure, thickness and growth rate can be influenced by negative power density through changing direction of ions movements, rate of ions exchanges and affecting formation of plasma. The CaP coatings reduced the substrate degradation rate. Calcium phosphates, such as hydroxyapatite (Ca10(PO4)6(OH)2, HA) and calcium pyrophosphate (Ca2P2O7, CPP), etc., were induced after 30 days SBF immersion, indicating that the coatings have bioactivity. The CaP coatings have no toxicity to cell and living mice, indicating that the coatings are safe to serve as implants. PMID:24140795

Pan, Y K; Chen, C Z; Wang, D G; Zhao, T G

2014-01-01

375

The Effects of Na2SiO3 Concentration on the Properties of Plasma Electrolytic Oxidation Coatings on 6060 Aluminum Alloy  

Science.gov (United States)

In this study, 6060 aluminum alloy was coated by plasma electrolytic oxidation (PEO) process. The effect of sodium silicate concentration (A solution-7.5 g/L—B solution-15 g/L) on various morphological properties and corrosion resistance of the surface was investigated. The correlation between the microwave sintering of 6060 aluminum alloy coated by PEO and non-microwave sintering of 6060 aluminum alloy properties are discussed. Detailed estimation of the quality of the coated metal surface was performed by additional testing of chemical compositions by EDS, crystalline structure of the films was examined using x-ray diffraction (XRD) and scanning electron microscope (SEM). The results showed that the oxidation layer was of typical morphology for the PEO process. The porosity amount of 6060 aluminum sample coated with 15 g/L was obtained higher than that of 7.5 g/L. In addition to, the porosity of all coated samples was decreased with increasing microwave sintering time. The corrosion resistance of coated samples with microwave sintering process was better than non-microwave sintering of 6060 aluminum alloy.

Becerik, D. Alexandre; Ayday, Aysun; Kumruo?lu, L. Cenk; Kurnaz, S. Can; Özel, Ahmet

2012-07-01

376

Pyrolyzed feather fibers for adsorbent and high temperature applications  

Science.gov (United States)

Chicken feather fibers (CFF) are problematic and costly for the poultry industry in terms of managing maintenance and disposal. Considering their great availability, low cost, and unique protein structure, CFF can be an environmentally friendly and bio-renewable candidate to replace petroleum products. CFF's low degradation and melting temperature render them useless at high temperatures. Pyrolysis methods were developed for CFF by using two temperature steps to convert them into high temperature resistant and adsorbent fibers while retaining their original physical appearance and affine dimensions. An intermolecular crosslinking mechanism in the first step of pyrolysis at 215 ºC for 24 h provided an intact fibrous structure with no subsequent melting. The evidence obtained from the thermal, bulk, and surface analysis techniques was indication of the simultaneous side chain degradation, polypeptide backbone scission, disulfide bond cleavage, and isopeptide crosslinking. The variation in the reaction kinetics of disulfide bond cleavage and isopeptide crosslinking played an important role in the melting transition. Consequently, long-lasting heat treatments below the melting point provided sufficient crosslinks in the protein matrix to keep the fibrous structure intact. Water-insoluble and crosslinked CFF reinforced the triglyceride-fatty acid based composites by providing a 15 fold increase in storage and tensile modulus at room temperature. These thermally stable fibers can be used instead of CFF in composites which may require high temperature compounding and molding processes. The second step of pyrolysis at 400--450 ºC for 1 h resulted in microporous fibers with a micropore volume of ˜0.18 cm3/g STP and with a narrower pore size distribution than commercial activated carbons through thermal degradation. Nearly all accessible pores in the microporous pyrolyzed chicken feather fibers (PCFF) had diameters less than 1 nm and therefore, showed a potential to be used in applications such as adsorption, storage, and separation of small gas molecules. The maximum excess H2 storage capacity was 1.5 wt% at 77 K and at pressures below 2 MPa. The notable H2 adsorption of PCFF below 1 MPa can be justified by the abundance of microporosity and the nanopores available for H2 penetration. In the second step of the pyrolysis the protein matrix went through a series of transformations including cyclization and aromatization reactions above the melting point. A partially cyclic carbon-nitrogen framework (carbon/nitrogen ratio=2.38) supported by double and triple bonds and oxygen functionalities is the suggested structural model for the PCFF. The useful fibers and adsorbents produced from CFF in this dissertation can encourage researchers to use high temperature heat treatments on keratin-based fibers. Also, the identified pyrolysis mechanisms can serve as a guide for producing materials with desired properties from protein-based materials, particularly in textile, high performance composite and catalyst industries.

Senoz, Erman

377

Polyethyleneimine incorporated metal-organic frameworks adsorbent for highly selective CO2 capture.  

Science.gov (United States)

A series of polyethyleneimine (PEI) incorporated MIL-101 adsorbents with different PEI loadings were reported for the first time in the present work. Although the surface area and pore volume of MIL-101 decreased significantly after loading PEI, all the resulting composites exhibited dramatically enhanced CO2 adsorption capacity at low pressures. At 100 wt% PEI loading, the CO2 adsorption capacity at 0.15 bar reached a very competitive value of 4.2?mmol g(-1) at 25°C, and 3.4?mmol g(-1) at 50°C. More importantly, the resulting adsorbents displayed rapid adsorption kinetics and ultrahigh selectivity for CO2 over N2 in the designed flue gas with 0.15?bar CO2 and 0.75?bar N2. The CO2 over N2 selectivity was up to 770 at 25°C, and 1200 at 50°C. We believe that the PEI based metal-organic frameworks is an attractive adsorbent for CO2 capture. PMID:23681218

Lin, Yichao; Yan, Qiuju; Kong, Chunlong; Chen, Liang

2013-01-01

378

Photoemission studies of clean and adsorbate covered metal surfaces using synchrotron and uv radiation sources  

Energy Technology Data Exchange (ETDEWEB)

Photoemission energy distribution experiments on clean metal and adsorbate-covered surfaces were performed under ultrahigh vacuum conditions by using x-ray and ultraviolet photon sources in the laboratory as well as continuously-tunable, highly polarized synchrotron radiation obtainable at the Stanford Synchrotron Radiation Laboratory (SSRL). Studies focused on two general areas: cross-section modulation in the photoemission process was studied as a function of photon energy and orbital composition. Sharp decreases in intensity of the valence bands of several transition metals (i.e., Ag, Au, and Pt) are attributed to the radial nodes in the respective wave functions. Adsorbate photoemission studies of CO adsorbed on platinum single crystals have demonstrated a very high spectral sensitivity to the 4sigma and (1..pi.. + 5sigma) peaks of CO at photon energies of 150 eV. Angle-resolved photoemission allowed determination of the orientation of CO chemisorbed on a Pt (111) or Ni(111) surface. Prelinimary results at high photon energies (approximately 150 eV) indicated scattering from the substrate which could yield chemisorption site geometries.

Apai, G.R. II

1977-09-01

379

Magnetic Fe3O4@C nanoparticles as adsorbents for removal of amoxicillin from aqueous solution.  

Science.gov (United States)

In the present study, powder activated carbon (PAC) combined with Fe(3)O(4) magnetite nanoparticles (MNPs) were used for the preparation of magnetic composites (MNPs-PAC), which was used as an adsorbent for amoxicillin (AMX) removal. The properties of magnetic activated carbon were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Brunaeur, Emmett and Teller and vibrating sample magnetometer. The operational factors affecting adsorption such as pH, contact time, adsorbent dosage, initial AMX concentration and temperature were studied in detail. The high surface area and saturation magnetization for the synthesized adsorbent were found to be 671.2 m(2)/g and 6.94 emu/g, respectively. The equilibrium time of the adsorption process was 90 min. Studies of adsorption equilibrium and kinetic models revealed that the adsorption of AMX onto MNPs-PAC followed Freundlich and Langmuir isotherms and pseudo-second-order kinetic models. The calculated values of the thermodynamic parameters, such as ?G°, ?H° and ?S° demonstrated that the AMX adsorption was endothermic and spontaneous in nature. It could be concluded that MNPs-PAC have a great potential for antibiotic removal from aquatic media. PMID:24434981

Kakavandi, Babak; Esrafili, Ali; Mohseni-Bandpi, Anoushiravan; Jonidi Jafari, Ahmad; Rezaei Kalantary, Roshanak

2014-01-01

380

Photoemission studies of clean and adsorbate covered metal surfaces using synchrotron and uv radiation sources  

International Nuclear Information System (INIS)

Photoemission energy distribution experiments on clean metal and adsorbate-covered surfaces were performed under ultrahigh vacuum conditions by using x-ray and ultraviolet photon sources in the laboratory as well as continuously-tunable, highly polarized synchrotron radiation obtainable at the Stanford Synchrotron Radiation Laboratory (SSRL). Studies focused on two general areas: cross-section modulation in the photoemission process was studied as a function of photon energy and orbital composition. Sharp decreases in intensity of the valence bands of several transition metals (i.e., Ag, Au, and Pt) are attributed to the radial nodes in the respective wave functions. Adsorbate photoemission studies of CO adsorbed on platinum single crystals have demonstrated a very high spectral sensitivity to the 4sigma and (1? + 5sigma) peaks of CO at photon energies of 150 eV. Angle-resolved photoemission allowed determination of the orientation of CO chemisorbed on a Pt (111) or Ni(111) surface. Prelinimary results at high photon energies (approximately 150 eV) indicated scattering from the substrate which could yield chemisorption site geometries

 
 
 
 
381

New finishing instruments for composite resins.  

Science.gov (United States)

The trimming of composite resin restorations encompasses gross finishing, contouring, fine finishing, and polishing. A series of aluminum oxide-coated flexible disks have been marketed and are suitable for that purpose. However, their use is confined to directly accessible convex surfaces. For precise finishing of small delineated areas, and for concave and occlusal surfaces, rigid rotary instruments are necessary. The currently used stones and tungsten carbide burs are ineffective with microfilled composite systems. Thus, a series of finishing burs coated with 40- and 15-microns diamond chips were evaluated because of the superior grinding effectiveness as compared with existing instruments. Surface roughness measurements, and qualitative and quantitative SEM evaluations, indicate that these fine and superfine diamond finishing burs produce surfaces on composite resins as smooth as tungsten carbide burs and stones. At the same time, they cause less surface and subsurface damage or marginal fractures on composite resin restorations. The three-year clinical experience is generally favorable. Further quantitative clinical studies are warranted. PMID:6579090

Lutz, F; Setcos, J C; Phillips, R W

1983-10-01

382

Polyethyleneimine Incorporated Metal-Organic Frameworks Adsorbent for Highly Selective CO2 Capture  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A series of polyethyleneimine (PEI) incorporated MIL-101 adsorbents with different PEI loadings were reported for the first time in the present work. Although the surface area and pore volume of MIL-101 decreased significantly after loading PEI, all the resulting composites exhibited dramatically enhanced CO2 adsorption capacity at low pressures. At 100 wt% PEI loading, the CO2 adsorption capacity at 0.15 bar reached a very competitive value of 4.2?mmol g?1 at 25°C, and 3.4?mmol g?1 ...

Lin, Yichao; Yan, Qiuju; Kong, Chunlong; Chen, Liang

2013-01-01

383

Effect of the surface inhomogeneity of the adsorbent on the diffusion of methane in micropores  

Energy Technology Data Exchange (ETDEWEB)

The effect of the adsorbent composition, surface structure, pore width, and temperature on the diffusion of methane in slitlike pores of coals was studied by the molecular dynamics method. Pore widths from 0.70 to 1.50 nm and temperatures of 111 and 298 K were considered. It was shown that the formation of methane layers leads to a nonmonotonic dependence of the longitudinal diffusion coefficient on the pore width and that the inhomogeneity of the surface adsorption field is responsible for the decrease in the diffusion coefficient.

Sizov, V.V.; Piotrovskaya, E.M.; Brodskaya, E.N. [St. Petersburg State University, St Petersburg (Russian Federation)

2003-04-01

384

The use of low-cost adsorbents for wastewater purification in mining industries.  

Science.gov (United States)

Recently, great attention has been paid to the environmental problems in mining industry. At present there are different ways of mineral processing, as well as various methods of wastewater treatment, most of them are expensive. Work is ongoing to find low-cost treatments. In this article, low-cost adsorbents, potentially useful for wastewater treatment on mining and metallurgical plants, are reviewed; their characteristics, advantages, and disadvantages of their application are compared. Also adsorption of different metals and radioactive compounds from acidic environment similar to composition of mining and metallurgical wastewaters is considered. PMID:23436121

Iakovleva, Evgenia; Sillanpää, Mika

2013-11-01

385

Neutron reflectivity study of adsorbed diblock copolymers  

International Nuclear Information System (INIS)

This paper summarizes our cumulative work on neutron reflectivity studies of polystyrene-poly(vinyl-2-pyridine) (PS-PVP) and polystyrenepolyethylene oxide (PS-PEO) adsorbed at a quartz-solvent interface. Deuterated toluene was chosen as the solvent since it is a good solvent for PS and a poor one for either of the other two blocks. In this case, the polystyrene dangles into the solvent while the other block acts as an anchor. The neutron reflectivity studies reveal that the form of the polymer density profile normal to the substrate may be varied from an extended ''brush'' to a condensed ''mushroom'' conformation by manipulating the ratio of the molecular weights of the two blocks. In addition, we present new data on the PS-PEO system in a poor solvent, deuterated cyclohexane, under conditions of shear flow in Poiseuille geometry. We find that when the PS-PEO diblock is absorbed from cyclohexane and is allowed to relax, the PS chain takes on a ''mushroom'' conformation. However, when the shear is applied, the layer shear thickens due to the PS chains extended to nearly twice their original lengths

386

Imaging the wave functions of adsorbed molecules.  

Science.gov (United States)

The basis for a quantum-mechanical description of matter is electron wave functions. For atoms and molecules, their spatial distributions and phases are known as orbitals. Although orbitals are very powerful concepts, experimentally only the electron densities and -energy levels are directly observable. Regardless whether orbitals are observed in real space with scanning probe experiments, or in reciprocal space by photoemission, the phase information of the orbital is lost. Here, we show that the experimental momentum maps of angle-resolved photoemission from molecular orbitals can be transformed to real-space orbitals via an iterative procedure which also retrieves the lost phase information. This is demonstrated with images obtained of a number of orbitals of the molecules pentacene (C22H14) and perylene-3,4,9,10-tetracarboxylic dianhydride (C24H8O6), adsorbed on silver, which are in excellent agreement with ab initio calculations. The procedure requires no a priori knowledge of the orbitals and is shown to be simple and robust. PMID:24344291

Lüftner, Daniel; Ules, Thomas; Reinisch, Eva Maria; Koller, Georg; Soubatch, Serguei; Tautz, F Stefan; Ramsey, Michael G; Puschnig, Peter

2014-01-14

387

HPLC determination of phenolics adsorbed on yeasts.  

Science.gov (United States)

An analytical HPLC method was developed to determine monomeric anthocyans as catechin (CA), flavonols as rutin (RU) and phenol acids as gallic acid (GA) adsorbed on the cell wall of 23 Saccharomyces cerevisiae strains grown on two media containing high levels of phenolic compounds, from grape seeds and grape skins, and on one control medium. Microbial biomass purification by liquid-liquid extraction of the phenolics is followed by reversed-phase chromatographic separation and CA, RU and GA detection by ultraviolet detector. The method was linear over the studied range of concentrations: GA at 0.12-0.96 microg/ml, CA at 0.25-20.00 microg/ml and RU at 0.02-0.20 microg/ml. The correlation coefficient for each analyte was greater than 0.9983. The recovery was greater than 85% for both GA and RU, and greater than 94% for CA. The detection limits for GA, CA and RU were determined to be 0.015, 0.025 and 0.029 microg/mg of biomass, respectively. The proposed method is highly responsive for the determination of different phenolics, and seems to be useful to evaluate their adsorption profile on yeasts. PMID:16631336

Rizzo, M; Ventrice, D; Varone, M A; Sidari, R; Caridi, A

2006-09-11

388

Application of a new adsorbent for fluoride removal from aqueous solutions  

International Nuclear Information System (INIS)

Highlights: • A new adsorbent has been prepared. • The adsorbent is non-toxic and easy to synthesize. • HBO1 has displayed best capacity for the removal of fluoride. • Unlike most adsorbents, HBO1 is suitable for the removal of fluoride from water. • The process of removal has been optimized. -- Abstract: Hydrous bismuth oxides (HBOs) have been investigated as a possible adsorbent for fluoride removal from water. Apart from bismuth trioxide (Bi2O3) compound, three additional HBOs, named as HBO1, HBO2, and HBO3 were synthesized in the laboratory and examined for their relative potentials for fluoride removal from aqueous solutions. HBO1 was observed to have highest fluoride removal at 10 mg/L initial concentration in aqueous environment. Among competitive anions, sulfate and chloride affect the fluoride removal by HBO1 more adversely than bicarbonate. Characterization of HBOs using X-ray diffraction (XRD) pattern analyses indicated crystalline structures, and the broad chemical composition of materials showed successive increase of Bi(OH)3 from HBO1 to HBO3, with decrease of BiOCl in the same order. Fourier Transform Infrared (FTIR) spectroscopy analyses indicated presence of Bi-O bond and successively increasing number of peaks corresponding to OH ion from HBO1 to HBO3. Scanning Electron Microscopic (SEM) images of HBOs show rough and porous structure of the materials. Presence of higher proportion of chloride compound in HBO1 with respect to others appears to be the factor responsible for its better performance in fluoride removal from aqueous solutions

389

PHYSICAL CHARACTERIZATION AND DESULFURIZATION OF BIOBRIQUETTE USING CALCIUM-BASED ADSORBENT  

Directory of Open Access Journals (Sweden)

Full Text Available Combustion of coal and co-combustion of their co-fuel contribute to gas emissions. Among the gas emissions are SOx, NOx, CO and CO2. Introduction of calcium based adsorbent is addressed to absorb SO2 that release to the atmosphere during the combustion process. Objective of the research is at first to observe the physical characteristics of biobriquettes as a function of briquette compositions (coal to palm kernel shell ratios and Ca/S ratios (Ca in adsorbent and S in briquette using a natural adsorbent (shellfish waste. The second objective is to investigate desulfurizationcharacteristics as a function of Ca/S ratios and desulfurization temperatures at coal to palm kernel shell ratio of 90:10 (wt %. Ratios of coal to palm kernel shell in this study are 90:10, 80:20, 70:30, 60:40 and 50:50; and Ca/S ratios are 1:1, 1.25:1, 1.5:1, 1.75:1 and 2:1. Binding agent used is the mixture of Jatropha curcas seeds and starch as much as 10% (wt. It was found that introducing the palm kernel shell and adsorbents in the coal briquette affect the water resistant and compressive strength. The highest water resistance and compressive strength were 5,165 second and 34 kg/cm2, respectively. The lowest SO2 level found in this study was 1 ppm for all Ca/S ratios, except for 1:1.

Khairil

2011-11-01

390

Multiscale structure, interfacial cohesion, adsorbed layers, miscibility and properties in dense polymer-particle mixtures  

Science.gov (United States)

A major goal in polymer nanocomposite research is to understand and predict how the chemical and physical nature of individual polymers and nanoparticles, and thermodynamic state (temperature, composition, solvent dilution, filler loading), determine bulk assembly, miscibility and properties. Microscopic PRISM theory provides a route to this goal for equilibrium disordered mixtures. A major prediction is that by manipulating the net polymer-particle interfacial attraction, miscibility is realizable via the formation of thin thermodynamically stable adsorbed layers, which, however, are destroyed by entropic depletion and bridging attraction effects if interface cohesion is too weak or strong, respectively. This and related issues are quantitatively explored for miscible mixtures of hydrocarbon polymers, silica nanospheres, and solvent using x-ray scattering, neutron scattering and rheology. Under melt conditions, quantitative agreement between theory and silica scattering experiments is achieved under both steric stabilization and weak depletion conditions. Using contrast matching neutron scattering to characterize the collective structure factors of polymers, particles and their interface, the existence and size of adsorbed polymer layers, and their consequences on microstructure, is determined. Failure of the incompressible RPA, accuracy of PRISM theory, the nm thickness of adsorbed layers, and qualitative sensitivity of the bulk modulus to interfacial cohesion and particle size are demonstrated for concentrated PEO-silica-ethanol nanocomposites. Temperature-dependent complexity is discovered when water is the solvent, and nonequilibrium effects emerge for adsorbing entangled polymers that strongly impact structure. By varying polymer chemistry, the effect of polymer-particle attraction on the intrinsic viscosity is explored with striking non-classical effects observed. This work was performed in collaboration with S.Y.Kim, L.M.Hall, C.Zukoski and B.Anderson.

Schweizer, Ken

2012-02-01

391

Application of a new adsorbent for fluoride removal from aqueous solutions  

Energy Technology Data Exchange (ETDEWEB)

Highlights: • A new adsorbent has been prepared. • The adsorbent is non-toxic and easy to synthesize. • HBO{sub 1} has displayed best capacity for the removal of fluoride. • Unlike most adsorbents, HBO{sub 1} is suitable for the removal of fluoride from water. • The process of removal has been optimized. -- Abstract: Hydrous bismuth oxides (HBOs) have been investigated as a possible adsorbent for fluoride removal from water. Apart from bismuth trioxide (Bi{sub 2}O{sub 3}) compound, three additional HBOs, named as HBO{sub 1}, HBO{sub 2}, and HBO{sub 3} were synthesized in the laboratory and examined for their relative potentials for fluoride removal from aqueous solutions. HBO{sub 1} was observed to have highest fluoride removal at 10 mg/L initial concentration in aqueous environment. Among competitive anions, sulfate and chloride affect the fluoride removal by HBO{sub 1} more adversely than bicarbonate. Characterization of HBOs using X-ray diffraction (XRD) pattern analyses indicated crystalline structures, and the broad chemical composition of materials showed successive increase of Bi(OH){sub 3} from HBO{sub 1} to HBO{sub 3}, with decrease of BiOCl in the same order. Fourier Transform Infrared (FTIR) spectroscopy analyses indicated presence of Bi-O bond and successively increasing number of peaks corresponding to OH ion from HBO{sub 1} to HBO{sub 3}. Scanning Electron Microscopic (SEM) images of HBOs show rough and porous structure of the materials. Presence of higher proportion of chloride compound in HBO{sub 1} with respect to others appears to be the factor responsible for its better performance in fluoride removal from aqueous solutions.

Srivastav, Arun Lal [Department of Applied Chemistry, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India); Singh, Prabhat K. [Department of Civil Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India); Srivastava, Varsha [Department of Applied Chemistry, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India); Sharma, Yogesh C., E-mail: ysharma.apc@itbhu.ac.in [Department of Applied Chemistry, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India)

2013-12-15

392

Neointimal coverage and vasodilator response to titanium-nitride-oxide-coated bioactive stents and everolimus-eluting stents in patients with acute coronary syndrome: insights from the BASE-ACS trial.  

Science.gov (United States)

Incomplete stent endothelialization is associated with late and very late stent thrombosis. In a post hoc analysis of the BASE-ACS trial, we sought to assess neointimal coverage and coronary flow reserve (CFR) 9 months after implantation of titanium-nitride-oxide-coated bioactive stents (BAS) versus everolimus-eluting stents (EES) in patients with acute coronary syndrome (ACS). In the BASE-ACS trial, 827 patients with ACS were randomized to receive either BAS or EES. In the current study, we examined neointimal growth and strut coverage by optical coherence tomography and CFR by trans-thoracic echocardiography in 28 consecutive non-diabetic patients with the culprit lesion in the left anterior descending coronary artery. The primary endpoints were binary stent strut coverage and CFR at 9-month follow-up. A total of 13 patients were included in the BAS group (2,033 struts); 15 in the EES group (2,898 struts). Binary stent strut coverage was higher and malapposed struts lower with BAS versus EES (99.4 vs 89.2, and 0.2 vs 4.6%, respectively, p < 0.001 for both). Neointimal hyperplasia thickness was greater with BAS versus EES (274.2 vs 100.1 ?m, respectively, p < 0.001). CFR was lower with EES versus BAS (2.2 ± 0.8 vs. 3.0 ± 0.5, respectively, p = 0.001). Abnormal CFR (<2.5) were detected in 10 patients in the EES group versus one in the BAS group (p = 0.002). The current study demonstrated that in patients with ACS, BAS resulted in improved neointimal stent strut coverage and better coronary vasodilator function as compared with EES at 9-month follow-up. PMID:23996244

Karjalainen, Pasi; Kiviniemi, Tuomas O; Lehtinen, Tuomas; Nammas, Wail; Ylitalo, Antti; Saraste, Antti; Mikkelsson, Jussi; Pietila, Mikko; Biancari, Fausto; Airaksinen, Juhani K E

2013-12-01

393

Two-dimensional two-component plasma with adsorbing impurities  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We study the behavior of the two-dimensional two-component plasma in the presence of some adsorbing impurities. Using a solvable model, we find analytic expressions for the thermodynamic properties of the plasma such as the $n$-body densities, the grand potential, and the pressure. We specialize in the case where there are one or two adsorbing point impurities in the plasma, and in the case where there are one or two parallel adsorbing lines. In the former case we study the ...

Ferrero, Alejandro; Tellez, Gabriel

2007-01-01

394

Optical spectroscopy of molecular-rotor molecules adsorbed on cellulose.  

Science.gov (United States)

Steady-state and time-resolved emission techniques were used to study the fluorescence properties of two molecular rotors, thioflavin-T and auramine-O adsorbed on cellulose powder. Molecular rotors are known for their weak fluorescence intensity and short fluorescence lifetime when dissolved in liquids of low viscosity. We found that these molecular-rotor molecules when adsorbed on cellulose exhibit a rather strong steady-state fluorescence spectrum as well as long emission lifetime. We explain these results by the inhibition of segmental intramolecular rotation when these molecules are adsorbed on cellulose. PMID:25185064

Simkovitch, Ron; Huppert, Dan

2014-09-25

395

FTIR spectroscopy of hydrogen, carbon monoxide, and methane adsorbed and co-adsorbed on zinc oxide  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Adsorption of dihydrogen, carbon monoxide and methane, and co-adsorption of H2/CO, H2/CH4 and CO/CH4 on zinc oxide was studied by means of Fourier transform infrared spectroscopy. Besides the already known dissociation of dihydrogen and molecular adsorption of CO, methane was found to be adsorbed molecularly on coordinatively unsaturated Zn2+ ions. Adsorption lowers the CH4 symmetry from Td to C3v, which is reflected in activation of the v1 (symmetric stretching) mode and discrete frequency s...

Zecchina, Adriano; Spoto, Giuseppe; Scarano, Domenica

2001-01-01

396

Preparation of a new adsorbent from activated carbon and carbon nanofiber (AC/CNF for manufacturing organic-vacbpour respirator cartridge  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract In this study a composite of activated carbon and carbon nanofiber (AC/CNF was prepared to improve the performance of activated carbon (AC for adsorption of volatile organic compounds (VOCs and its utilization for respirator cartridges. Activated carbon was impregnated with a nickel nitrate catalyst precursor and carbon nanofibers (CNF were deposited directly on the AC surface using catalytic chemical vapor deposition. Deposited CNFs on catalyst particles in AC micropores, were activated by CO2 to recover the surface area and micropores. Surface and textural characterizations of the prepared composites were investigated using Brunauer, Emmett and Teller’s (BET technique and electron microscopy respectively. Prepared composite adsorbent was tested for benzene, toluene and xylene (BTX adsorption and then employed in an organic respirator cartridge in granular form. Adsorption studies were conducted by passing air samples through the adsorbents in a glass column at an adjustable flow rate. Finally, any adsorbed species not retained by the adsorbents in the column were trapped in a charcoal sorbent tube and analyzed by gas chromatography. CNFs with a very thin diameter of about 10-20 nm were formed uniformly on the AC/CNF. The breakthrough time for cartridges prepared with CO2 activated AC/CNF was 117 minutes which are significantly longer than for those cartridges prepared with walnut shell- based activated carbon with the same weight of adsorbents. This study showed that a granular form CO2 activated AC/CNF composite could be a very effective alternate adsorbent for respirator cartridges due to its larger adsorption capacities and lower weight.

Forushani Abbas Rahimi

2013-01-01

397

Preparation of a new adsorbent from activated carbon and carbon nanofiber (AC/CNF) for manufacturing organic-vacbpour respirator cartridge.  

Science.gov (United States)

In this study a composite of activated carbon and carbon nanofiber (AC/CNF) was prepared to improve the performance of activated carbon (AC) for adsorption of volatile organic compounds (VOCs) and its utilization for respirator cartridges. Activated carbon was impregnated with a nickel nitrate catalyst precursor and carbon nanofibers (CNF) were deposited directly on the AC surface using catalytic chemical vapor deposition. Deposited CNFs on catalyst particles in AC micropores, were activated by CO2 to recover the surface area and micropores. Surface and textural characterizations of the prepared composites were investigated using Brunauer, Emmett and Teller's (BET) technique and electron microscopy respectively. Prepared composite adsorbent was tested for benzene, toluene and xylene (BTX) adsorption and then employed in an organic respirator cartridge in granular form. Adsorption studies were conducted by passing air samples through the adsorbents in a glass column at an adjustable flow rate. Finally, any adsorbed species not retained by the adsorbents in the column were trapped in a charcoal sorbent tube and analyzed by gas chromatography. CNFs with a very thin diameter of about 10-20 nm were formed uniformly on the AC/CNF. The breakthrough time for cartridges prepared with CO2 activated AC/CNF was 117 minutes which are significantly longer than for those cartridges prepared with walnut shell- based activated carbon with the same weight of adsorbents. This study showed that a granular form CO2 activated AC/CNF composite could be a very effective alternate adsorbent for respirator cartridges due to its larger adsorption capacities and lower weight. PMID:23369424

Jahangiri, Mehdi; Adl, Javad; Shahtaheri, Seyyed Jamaleddin; Rashidi, Alimorad; Ghorbanali, Amir; Kakooe, Hossein; Forushani, Abbas Rahimi; Ganjali, Mohammad Reza

2013-01-01

398

Preparation of a New Adsorbent from Activated Carbon and Carbon Nanofiber (AC/CNF for Manufacturing Organic-Vacbpour Respirator Cartridge  

Directory of Open Access Journals (Sweden)

Full Text Available In this study a composite of activated carbon and carbon nanofiber (AC/CNF was prepared to improve the performance of activated carbon (AC for adsorption of volatile organic compounds (VOCs and its utilization for respirator cartridges. Activated carbon was impregnated with a nickel nitrate catalyst precursor and carbonnanofibers (CNF were deposited directly on the AC surface using catalytic chemical vapor deposition. Deposited CNFs on catalyst particles in AC micropores, were activated by CO2 to recover the surface area and micropores.Surface and textural characterizations of the prepared composites were investigated using Brunauer, Emmett andTeller’s (BET technique and electron microscopy respectively. Prepared composite adsorbent was tested forbenzene, toluene and xylene (BTX adsorption and then employed in an organic respirator cartridge in granularform. Adsorption studies were conducted by passing air samples through the adsorbents in a glass column at an adjustable flow rate. Finally, any adsorbed species not retained by the adsorbents in the column were trapped in a charcoal sorbent tube and analyzed by gas chromatography. CNFs with a very thin diameter of about 10-20 nmwere formed uniformly on the AC/CNF. The breakthrough time for cartridges prepared with CO2 activated AC/CNF was 117 minutes which are significantly longer than for those cartridges prepared with walnut shell- based activated carbon with the same weight of adsorbents. This study showed that a granular form CO2 activated AC/CNF composite could be a very effective alternate adsorbent for respirator cartridges due to its larger adsorption capacities and lower weight.

Mehdi Jahangiri

2013-01-01

399

Chirped pulse Two Photon Photoemission technique to study adsorbate dynamics  

Energy Technology Data Exchange (ETDEWEB)

Time resolved Two Photon Photoemission (TR 2PPE) is a well-known method in surface physics to study adsorbate dynamics. However, it's temporal resolution is limited by the Heisenberg uncertainty principle. Here we propose a novel method to observe dynamics of adsorbate states using Chirped Pulse Two Photon Photoemission (CP 2PPE). This method utilizes a suitable modified spectral phase of the exciting femtosecond laser pulse, modulated by a Fork prism pair. We apply this technique in the case of Cs/Cu(111), where we observe significant energy shifts of the excited adsorbate state (Cs*) as well as a peak broadening. The obeserved asymmetry in peak position is suggestive of possible adsorbate motion. We further propose to apply the method of CP 2PPE to systems with shorter time constants where time resolved methods are restricted.

Bader, Marianne; Sarkar, Indranil; Steeb, Felix; Ruffing, Andreas; Aeschlimann, Martin [Department of Physics, University of Kaiserslautern, 67663 Kaiserslautern (Germany)

2010-07-01

400

Electronic structure of benzene adsorbed on Ni and Cu surfaces  

International Nuclear Information System (INIS)

Benzene has for a long time served as a prototype adsorption system of large molecules. It adsorbs with the molecular plane parallel to the surface. The bonding of benzene to a transition metal is typically viewed to involve the ? system. Benzene adsorbs weakly on Cu and strongly on Ni. It is interesting to study how the adsorption strength is reflected in the electronic structure of the adsorbate-substrate complex. The authors have used X-ray Emission (XE) and X-ray Absorption (XA) spectroscopies to selectively study the electronic states localized on the adsorbed benzene molecule. Using XES the occupied states can be studies and with XAS the unoccupied states. The authors have used beamline 8.0 and the Swedish endstation equipped with a grazing incidence x-ray spectrometer and a partial yield absorption detector. The resolution in the XES and XAS were 0.5 eV and 0.05 eV, respectively