WorldWideScience
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

Bioactive plasma electrolytic oxidation coatings--the role of the composition, microstructure, and electrochemical stability.  

Science.gov (United States)

A Plasma electrolytic oxidation (PEO) process was used to produce bioactive coatings on Ti. PEO coatings with Ca/P atomic ratio of 1.7 and 4.0 were fabricated and characterized with respect to their morphology, composition, and microstructure. AC and DC electrochemical tests were used to evaluate the effect of (i) organic additives (amino acids, proteins, vitamins, and antibiotics) in alpha-minimum essential medium (?-MEM) on electrochemical stability of noncoated and PEO-coated Ti and (ii) coating composition, microstructure, and corrosion behavior on the cell response in ?-MEM. PEO-coated Ti showed higher corrosion resistance than the noncoated Ti in MEM with and without organic additives by an order of magnitude. The corrosion resistance in ?-MEM decreased with time for nonmodified Ti and increased for PEO-coated Ti; the latter was because of the adsorption of the proteins in the coating pores which increased the diffusion resistance. The presence of Ca and P in titanium oxide coating at the Ca/P ratio exceeding that of any stoichiometric Ca-P-O and Ca-P-O-H compounds facilitates faster osteoblast cell adhesion. PMID:23744783

Mohedano, M; Guzman, R; Arrabal, R; López Lacomba, J-L; Matykina, E

2013-11-01

3

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

4

Structure and Properties of Microarc Oxidation Coatings on SiCP/AZ31 Magnesium Matrix Composite  

Directory of Open Access Journals (Sweden)

Full Text Available The protective ceramic coatings were prepared on SiC particle reinforced magnesium matrix composite by microarc oxidation (MAO surface treatment technique. The surface morphology, cross-sectional microstructure and phase constituent of ceramic coatings were analyzed. And the microhardness profile, thermal shock resistance and electrochemical corrosion behavior of the coatings were measured. The ceramic coating consists of MgO, Mg2SiO4 and a few phases related to the electrolyte elements. Furthermore, a few residual SiC reinforced particles are also remained in the coatings. The maximum hardness of the coating is about HV800, which is at least five times higher than that of the uncoated composite substrate. The coatings do not detach from composite substrate after the coated samples undergo 100 thermal shocks, heating the sample to 500¡?nd then quenching into water, which displays a good thermal shock resistance for the MAO coatings on SiCP/AZ31 composite. In addition, after MAO surface treatment, the corrosion resistance of the SiCP/AZ31 composite is greatly improved.

XUE Wen-Bin,JIN Qian,ZHU Qing-Zhen,MA Yue-Yu

2009-05-01

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

Effect of current density on the structure, composition and corrosion resistance of plasma electrolytic oxidation coatings on Mg–Li alloy  

International Nuclear Information System (INIS)

Highlights: ? The PEO coatings exhibit tunable characteristics by controlling the current density. ? The coating formed at 5 A/dm2 exhibits the highest corrosion resistance. ? Anti-corrosion properties of PEO coatings are related to coating surface composition. - Abstract: The effect of current density on the oxidation process, morphology, composition and anti-corrosion properties of coatings are elucidated. X-ray photoelectron spectroscopy and X-ray diffraction analysis of coatings show that coatings prepared at different current densities are composed of MgO and ?-Mg2SiO4 and ?-Mg2SiO4 phase. The chemical composition of PEO coatings varies from surface to the interior of the oxide coating. The PEO coatings exhibit tunable thickness, composition ratio, and porosity by controlling the current density, which ultimately affects film morphology and anti-corrosion properties. The superior corrosion resistance of coating obtained at 5 A/dm2 is attributed to the compactness of the barrier layer and the highest MgO/Mg2SiO4 ratio.

8

Effect of current density on the structure, composition and corrosion resistance of plasma electrolytic oxidation coatings on Mg-Li alloy  

Energy Technology Data Exchange (ETDEWEB)

Highlights: Black-Right-Pointing-Pointer The PEO coatings exhibit tunable characteristics by controlling the current density. Black-Right-Pointing-Pointer The coating formed at 5 A/dm{sup 2} exhibits the highest corrosion resistance. Black-Right-Pointing-Pointer Anti-corrosion properties of PEO coatings are related to coating surface composition. - Abstract: The effect of current density on the oxidation process, morphology, composition and anti-corrosion properties of coatings are elucidated. X-ray photoelectron spectroscopy and X-ray diffraction analysis of coatings show that coatings prepared at different current densities are composed of MgO and {gamma}-Mg{sub 2}SiO{sub 4} and {alpha}-Mg{sub 2}SiO{sub 4} phase. The chemical composition of PEO coatings varies from surface to the interior of the oxide coating. The PEO coatings exhibit tunable thickness, composition ratio, and porosity by controlling the current density, which ultimately affects film morphology and anti-corrosion properties. The superior corrosion resistance of coating obtained at 5 A/dm{sup 2} is attributed to the compactness of the barrier layer and the highest MgO/Mg{sub 2}SiO{sub 4} ratio.

Li, Zhijun [Key Laboratory of Superlight Materials and Surface Technology, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Yuan, Yi, E-mail: yi.yuan@hrbeu.edu.cn [Key Laboratory of Superlight Materials and Surface Technology, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Jing, Xiaoyan [Key Laboratory of Superlight Materials and Surface Technology, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China)

2012-11-15

9

Dual-protection of a graphene-sulfur composite by a compact graphene skin and an atomic layer deposited oxide coating for a lithium-sulfur battery.  

Science.gov (United States)

A reduced graphene oxide (rGO)-sulfur composite aerogel with a compact self-assembled rGO skin was further modified by an atomic layer deposition (ALD) of ZnO or MgO layer, and used as a free-standing electrode material of a lithium-sulfur (Li-S) battery. The rGO skin and ALD-oxide coating worked as natural and artificial barriers to constrain the polysulfides within the cathode region. As a result, the Li-S battery based on this electrode material exhibited superior cycling stability, good rate capability and high coulombic efficiency. Furthermore, ALD-ZnO coating was tested for performance improvement and found to be more effective than ALD-MgO coating. The ZnO modified G-S electrode with 55 wt% sulfur loading delivered a maximum discharge capacity of 998 mA h g(-1) at a current density of 0.2 C. A high capacity of 846 mA h g(-1) was achieved after charging/discharging for 100 cycles with a coulombic efficiency of over 92%. In the case of using LiNO3 as a shuttle inhibitor, this electrode showed an initial discharge capacity of 796 mA h g(-1) and a capacity retention of 81% after 250 cycles at a current density of 1 C with an average coulombic efficiency higher than 99.7%. PMID:25721407

Yu, Mingpeng; Wang, Aiji; Tian, Fuyang; Song, Hongquan; Wang, Yinshu; Li, Chun; Hong, Jong-Dal; Shi, Gaoquan

2015-03-12

10

Dual-protection of a graphene-sulfur composite by a compact graphene skin and an atomic layer deposited oxide coating for a lithium-sulfur battery  

Science.gov (United States)

A reduced graphene oxide (rGO)-sulfur composite aerogel with a compact self-assembled rGO skin was further modified by an atomic layer deposition (ALD) of ZnO or MgO layer, and used as a free-standing electrode material of a lithium-sulfur (Li-S) battery. The rGO skin and ALD-oxide coating worked as natural and artificial barriers to constrain the polysulfides within the cathode region. As a result, the Li-S battery based on this electrode material exhibited superior cycling stability, good rate capability and high coulombic efficiency. Furthermore, ALD-ZnO coating was tested for performance improvement and found to be more effective than ALD-MgO coating. The ZnO modified G-S electrode with 55 wt% sulfur loading delivered a maximum discharge capacity of 998 mA h g-1 at a current density of 0.2 C. A high capacity of 846 mA h g-1 was achieved after charging/discharging for 100 cycles with a coulombic efficiency of over 92%. In the case of using LiNO3 as a shuttle inhibitor, this electrode showed an initial discharge capacity of 796 mA h g-1 and a capacity retention of 81% after 250 cycles at a current density of 1 C with an average coulombic efficiency higher than 99.7%.A reduced graphene oxide (rGO)-sulfur composite aerogel with a compact self-assembled rGO skin was further modified by an atomic layer deposition (ALD) of ZnO or MgO layer, and used as a free-standing electrode material of a lithium-sulfur (Li-S) battery. The rGO skin and ALD-oxide coating worked as natural and artificial barriers to constrain the polysulfides within the cathode region. As a result, the Li-S battery based on this electrode material exhibited superior cycling stability, good rate capability and high coulombic efficiency. Furthermore, ALD-ZnO coating was tested for performance improvement and found to be more effective than ALD-MgO coating. The ZnO modified G-S electrode with 55 wt% sulfur loading delivered a maximum discharge capacity of 998 mA h g-1 at a current density of 0.2 C. A high capacity of 846 mA h g-1 was achieved after charging/discharging for 100 cycles with a coulombic efficiency of over 92%. In the case of using LiNO3 as a shuttle inhibitor, this electrode showed an initial discharge capacity of 796 mA h g-1 and a capacity retention of 81% after 250 cycles at a current density of 1 C with an average coulombic efficiency higher than 99.7%. Electronic supplementary information (ESI) available: Procedures of ALD operation, supplementary figures and details of theoretical simulations. See DOI: 10.1039/c5nr00166h

Yu, Mingpeng; Wang, Aiji; Tian, Fuyang; Song, Hongquan; Wang, Yinshu; Li, Chun; Hong, Jong-Dal; Shi, Gaoquan

2015-03-01

11

REVIEW: USE of COMPOSITE ADSORBENTS in ADSORPTION REFRIGERATION  

Directory of Open Access Journals (Sweden)

Full Text Available The urbanization across the world has resulted in increased demand for refrigeration and air conditioning. The main disadvantage with the conventional method i.e. vapor compression system is environment pollution. Another problem faced during urbanization is energy crisis. The adsorption refrigeration system is one of the solutions to this problem. The advantages of this system are environment friendly, less noise, use of waste heat or solar energy. But the disadvantage with adsorption system is low coefficient of performance (COP and bulkiness. Researchers across the world are working on this issue to make adsorption system a viable alternative to the compression systems. Since the last two decades considerable work is being done on the use of composite adsorbents to improve the heat and mass transfer performance. This kind of adsorbent is usually obtained by the combination of a chemical adsorbents and physical adsorbents.

Satishchandra V. Joshi

2012-01-01

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

Study on the adsorption performance of composite adsorbent of CaCl2 and expanded graphite with ammonia as adsorbate  

International Nuclear Information System (INIS)

A novel constant volume test unit was built to study the adsorption performance of a new type composite adsorbent. This test unit can measure the adsorption isosteres of the working pairs. The adsorption isosteres are the curves of the adsorption pressure variation with the adsorption temperatures at constant adsorption quantities. Compared to the former test results of isothermals and isobars, the isosteres are better for the calculation of the adsorption heat, desorption heat and the selection the adsorption working pairs. Three experimental results were obtained: the first result was that the expanded graphite powders were superior to the expandable graphite powders to facilitate the transportation of working fluid in the composite adsorbent. The second one was that the composite adsorbent treated by solution is more homogeneous than the simple mixed composite adsorbent and the treated composite adsorbent has a better mass transfer performance. The last one was that the adsorption isosteres was the same one not only in the heating process but also in the cooling process and this performance was not relevant to the homogeneity of the composite adsorbent

14

Uranium extraction from sea water with composite adsorbents, (4)  

International Nuclear Information System (INIS)

Composite hydrous titanium(IV)-iron(II) oxides prepared by precipitation from homogeneous solutions were studied with a view to developing magnetic adsorbents for uranium extraction from sea water. Higher uranium adsorption capacity was registered with homogeneous than with heterogeneous solution used for preparing the oxide. The adsorbents for uranium prepared from homogeneous solution moreover were found to require the copresence of urea and a suitable anion such as So42-, in order to provide strongly active adsorption of uranium. The value of saturated magnetization of the composite hydrous oxides decreased with increasing titanium mole fraction up to 0.75, increase of the titanium mole fraction had, on the other hand, the effect of enhancing uranium adsorption capacity, which however saturated beyond 0.75 titanium mole fraction. The change of enthalpy brought by the uranium adsorption on the composite hydrous titanium(IV)-iron(II) oxides was 10 kcal/mol, and the amount of change independent of the conditions of precipitation. (author)

15

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

Science.gov (United States)

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 WO 3, Ta 2O 5 and SiO 2. Raman spectroscopy showed that the outer layer of oxide coatings formed during the PEO process is silicate tungsten bronze.

Petkovi?, M.; Stojadinovi?, S.; Vasili?, R.; Zekovi?, Lj.

2011-10-01

16

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.

17

Design and performance prediction of a new generation adsorption chiller using composite adsorbent  

International Nuclear Information System (INIS)

Research highlights: ? Composite adsorbent 'employing lithium chloride in silica gel' and water as working pair. ? A new type adsorbent bed is used to accommodate the composite adsorbent. ? A dynamic model of the adsorption chiller is built. ? The coefficient of performance (COP) and the cooling capacity will be improved. -- Abstract: This paper presents a novel adsorption chiller using composite adsorbent 'employing lithium chloride in silica gel' as adsorbent and water as adsorbate. A new type adsorbent bed is used to accommodate the composite adsorbent. The mass recovery between two adsorbent beds usually results in the adsorbate unbalance. So a novel auto water makeup unite is used to solve the problem. A dynamic model of the adsorption chiller is built based on the adsorption isotherms to predict the performance. The simulation result shows that the coefficient of performance (COP) and the cooling capacity will increase by using this new composite adsorbent. When the temperatures of hot water inlet, cooling water inlet, and chilled water inlet are 363, 303 and 293 K, COP will be 0.43, and the cooling capacity will be 5.295 kW. Also operation strategy is optimized. Different temperatures of hot water inlet, cooling water inlet and chilling water inlet will result in different COP and cooling capacity.

18

Recovery of uranium from seawater by composite fiber adsorbent  

International Nuclear Information System (INIS)

The authors of this paper developed a composite fiber adsorbent (CFA) to entrap finely powdered amidoxime into fibrils of supporting material with silica in a previous report. This was further tested for uranyl recovery directly from seawater. The adsorption rate showed a flow rate dependence with almost a saturation value of ?100 ?g of U/g of CFA at a mean flow rate of sea current. Chemical as well as physical deterioration was overcome by using 1 N NaHCO3 and 0.72 M NaCl as liberating and washing agents, to keep the pH and ionic strength, respectively, constant, and the initial adsorption rate was maintained even after a recycle time of 50. A continuous passage of seawater showed a linear increase of the adsorption to afford 1560 ?g of U/g of CFA after 3 weeks

19

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

20

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

21

Effect of pulse frequency on the microstructure, phase composition and corrosion performance of a phosphate-based plasma electrolytic oxidation coated AM50 magnesium alloy  

International Nuclear Information System (INIS)

An AM50 magnesium alloy was plasma electrolytic oxidation treated using a pulsed DC power supply at three different pulse frequencies viz., 10 Hz, 100 Hz and 1000 Hz with a constant pulse ratio for 15 min in an alkaline phosphate electrolyte. The resultant coatings were characterized by X-ray diffraction, energy dispersive spectroscopy and scanning electron microscopy for their phase composition and microstructural features. The 10 Hz condition yielded relatively thick and rough coatings, which was attributed to the higher energy input per individual pulse during the PEO processing. The phase composition was also found to be influenced by the processing frequency. Electrochemical impedance spectroscopy studies performed in 0.1 M NaCl solutions revealed that the coatings produced at 10 Hz condition had a better corrosion resistance, which was attributed to the higher thickness, more compact microstructural features and a relatively stable phase composition.

22

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

OpenAIRE

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) whe...

Azhar Abdul Halim; Noor Nazurah Zainal Abidin; Normah Awang; Anuar Ithnin; Mohd Sham Othman; Mohd Ikram Wahab

2011-01-01

23

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)

24

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

Directory of Open Access Journals (Sweden)

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

25

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

26

Biocompatibility of Ir/Ti-oxide coatings: Interaction with platelets, endothelial and smooth muscle cells  

Energy Technology Data Exchange (ETDEWEB)

Graphical abstract: - Highlights: • Ir/Ti-oxide coated surfaces are characterized by the so-called “cracked-mud” morphology. • 40% Ir in the coating material results in a morphologically uniform coating. • ECs and SMCs showed a desirable response to the Ir/Ti-oxide coated surfaces. • Ir/Ti-oxide coated surfaces are more bio/hemocompatible than the untreated 316L stainless steel. - Abstract: Applying surface coatings on a biomedical implant is a promising modification technique which can enhance the implant's biocompatibility via controlling blood constituents- or/and cell-surface interaction. In this study, the influence of composition of Ir{sub x}Ti{sub 1?x}-oxide coatings (x = 0, 0.2, 0.4, 0.6, 0.8, 1) formed on a titanium (Ti) substrate on the responses of platelets, endothelial cells (ECs) and smooth muscle cells (SMCs) was investigated. The results showed that a significant decrease in platelet adhesion and activation was obtained on Ir{sub 0.2}Ti{sub 0.8}-oxide and Ir{sub 0.4}Ti{sub 0.6}-oxide coatings, rendering the surfaces more blood compatible, in comparison to the control (316L stainless steel, 316L-SS) and other coating compositions. Further, a substantial increase in the EC/SMC surface count ratio after 4 h of cell attachment to the Ir{sub 0.2}Ti{sub 0.8}-oxide and Ir{sub 0.4}Ti{sub 0.6}-oxide coatings, relative to the 316L-SS control and the other coating compositions, indicated high potential of these coatings for the enhancement of surface endothelialization. This indicates the capability of the corresponding coating compositions to promote EC proliferation on the surface, while inhibiting that of SMCs, which is important in cardiovascular stents applications.

Habibzadeh, Sajjad [Department of Chemical Engineering, McGill University, Montreal, QC (Canada); Li, Ling [Department of Anatomy and Cell Biology, McGill University, Montreal, QC (Canada); Omanovic, Sasha [Department of Chemical Engineering, McGill University, Montreal, QC (Canada); Shum-Tim, Dominique [Divisions of Cardiac Surgery and Surgical Research, Department of Surgery, McGill University, Montreal, QC (Canada); Davis, Elaine C., E-mail: elaine.davis@mcgill.ca [Department of Anatomy and Cell Biology, McGill University, Montreal, QC (Canada)

2014-05-01

27

Biocompatibility of Ir/Ti-oxide coatings: Interaction with platelets, endothelial and smooth muscle cells  

International Nuclear Information System (INIS)

Graphical abstract: - Highlights: • Ir/Ti-oxide coated surfaces are characterized by the so-called “cracked-mud” morphology. • 40% Ir in the coating material results in a morphologically uniform coating. • ECs and SMCs showed a desirable response to the Ir/Ti-oxide coated surfaces. • Ir/Ti-oxide coated surfaces are more bio/hemocompatible than the untreated 316L stainless steel. - Abstract: Applying surface coatings on a biomedical implant is a promising modification technique which can enhance the implant's biocompatibility via controlling blood constituents- or/and cell-surface interaction. In this study, the influence of composition of IrxTi1?x-oxide coatings (x = 0, 0.2, 0.4, 0.6, 0.8, 1) formed on a titanium (Ti) substrate on the responses of platelets, endothelial cells (ECs) and smooth muscle cells (SMCs) was investigated. The results showed that a significant decrease in platelet adhesion and activation was obtained on Ir0.2Ti0.8-oxide and Ir0.4Ti0.6-oxide coatings, rendering the surfaces more blood compatible, in comparison to the control (316L stainless steel, 316L-SS) and other coating compositions. Further, a substantial increase in the EC/SMC surface count ratio after 4 h of cell attachment to the Ir0.2Ti0.8-oxide and Ir0.4Ti0.6-oxide coatings, relative to the 316L-SS control and the other coating compositions, indicated high potential of these coatings for the enhancement of surface endothelialization. This indicates the capability of the corresponding coating compositions to promote EC proliferation on the surface, while inhibiting that of SMCs, which is important in cardiovascular stents applications

28

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

29

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

30

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

31

Protective oxide coating on the surface of steel St20  

International Nuclear Information System (INIS)

The authors investigated the stability of oxide coatings on the surface of pearlitic steel 20 at 90 degree C in an aqueous medium. The article examines the influence of the flow rate and of the presence of corrosion products of iron on the protective effect of the oxide coating. On the basis of the results of the investigations obtained with the aid of the radionuclides 59Fe, 54Mn, 137Cs the conclusion is reached that the oxide coating is not restored and does not peel off. The assumption is voiced that a layer of hydroxide forms between the metal and the oxide coating

32

Preparation and properties of the zinc-activated carbon composite adsorbent for extraction of uranium from sea water  

International Nuclear Information System (INIS)

Basic zinc carbonate-activated carbon composite adsorbents were prepared under various conditions. Chemical composition of the composite adsorbents was determined by chemical analysis, X-ray diffraction, thermal analysis, and IR study. Most products revealed the same pattern of X-ray diffraction and the other properties as the basic zinc carbonate (ZnCO3.3Zn(OH)2.H2O). A new phase which had different X-ray pattern and higher decomposition temperature wasfound in some cases. Relating to the solubility and adsorption capacity of uranium, there was no distinct difference between this new phase and ordinary basic zinc carbonate composite adsorbents. (author)

33

Raman and IR spectroscopic investigation of As adsorbed on Mn3O4 magnetic composites  

Science.gov (United States)

Raman and IR spectra were recorded of the As-loaded Mn3O4 magnetic composites obtained from the adsorption studies performed with As(III). XANES results for the composite after As(III) removal tests show that the As adsorbed is at the oxidized arsenic form, As(V). Monodentate and bidentate surface complexes are suggested for arsenic adsorption onto the composite (5-16 mg/g). Precipitation of manganese arsenate is observed for high As loading (35 mg/g).

Silva, Gabriela C.; Almeida, Fabiana S.; Dantas, Maria Sylvia S.; Ferreira, Angela M.; Ciminelli, Virginia S. T.

34

Modeling of fixed-bed column studies for the adsorption of cadmium onto novel polymer-clay composite adsorbent  

International Nuclear Information System (INIS)

Kaolinite clay was treated with polyvinyl alcohol to produce a novel water-stable composite called polymer-clay composite adsorbent. The modified adsorbent was found to have a maximum adsorption capacity of 20,400 ± 13 mg/L (1236 mg/g) and a maximum adsorption rate constant of ?7.45 x 10-3 ± 0.0002 L/(min mg) at 50% breakthrough. Increase in bed height increased both the breakpoint and exhaustion point of the polymer-clay composite adsorbent. The time for the movement of the Mass Transfer Zone (?) down the column was found to increase with increasing bed height. The presence of preadsorbed electrolyte and regeneration were found to reduce this time. Increased initial Cd2+ concentration, presence of preadsorbed electrolyte, and regeneration of polymer-clay composite adsorbent reduced the volume of effluent treated. Premodification of polymer-clay composite adsorbent with Ca- and Na-electrolytes reduced the rate of adsorption of Cd2+ onto polymer-clay composite and lowered the breakthrough time of the adsorbent. Regeneration and re-adsorption studies on the polymer-clay composite adsorbent presented a decrease in the bed volume treated at both the breakpoint and exhaustion points of the regenerated bed. Experimental data were observed to show stronger fits to the Bed Depth Service Time (BDST) model than the Thomas model.

35

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

International Nuclear Information System (INIS)

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 Kd,Cs value of 3.8 x 104 cm3/g was obtained for KCoFC-SG (Davi.) composite. KCoFC-SG (NH, MB5D) and T-KCFC also had relatively large Kd,Cs values above 1.0 x 104 cm3/g. The uptake rate of Cs+ ions was examined by batch method. KCoFC-SG (NH, MB5D) and AMP-SG (Davi.) had relatively large uptake rate of Cs+, and the uptake attained equilibrium within 1 h. The maximum uptake capacity of Cs+ 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+ ions (0.23 mmol/g > 0.17 mmol/g (T-KCFC)) and this composite also had a selectivity towards Sr2+ ions; KCoFC-X is effective adsorbent for both Cs+ and Sr2+ ions. The largest value of Kd,Sr was estimated to be 218 cm3/g for titanic acid-PAN. Titanic acid-PAN had the largest uptake rate of Sr2+ 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+ and RuNO3+ ions. KCoFC-SG (NH), KCoFC-CP and T-KCFC had higher selectivity towards Cs+ than other adsorbents; these adsorbents had adsorbability to Cs+ ions even in the presence of Ba2+, Ca2+ and Mg2+ ions. The separation factor of Kd,Sr/Kd,Ba for titanic acid-PAN was about 1, indicating that the Kd,Sr for titanic acid-PAN tends to decrease with Ba2+ concentration. As for the breakthrough properties, the largest 5 % breakpoint and 5 % breakthrough capacity of Cs+ ions were estimated to be 47.1 cm3 and 0.07 mmol/g for the column of KCoFC-SG (NH), respectively. The order of 5 % breakthrough capacity of Cs+ 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+ ions, and KCoFC-X composite was useful for the uptake of both Cs+ and Sr2+ ions. The estimation of irradiation stability and the uptake properties using the actual wastes are further essential for the practical operation. (authors)

36

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

37

Structure and chemical composition of layers adsorbed at interfaces with champagne.  

Science.gov (United States)

The structure and the chemical composition of the layer adsorbed at interfaces involving champagne have been investigated using native champagne, as well as ultrafiltrate (UFch) and ultraconcentrate (UCch) obtained by ultrafiltration with a 10(4) nominal molar mass cutoff. The layer adsorbed at the air/liquid interface was examined by surface tension and ellipsometry kinetic measurements. Brewster angle microscopy demonstrated that the layer formed on polystyrene by adsorption or drop evaporation was heterogeneous, with a domain structure presenting similarities with the layer adsorbed at the air/liquid interface. The surface chemical composition of polystyrene with the adlayer was determined by X-ray photoelectron spectroscopy (XPS). The contribution of champagne constituents varied according to the liquid (native, UFch, and UCch) and to the procedure of adlayer formation (evaporation, adsorption, and adsorption + rinsing). However, their chemical composition was not significantly influenced either by ultrafiltration or by the procedure of deposition on polystyrene. Modeling this composition in terms of classes of model compounds gave approximately 35% (w/w) of proteins and 65% (w/w) of polysaccharides. In the adlayer, the carboxyl groups or esters represent about 18% of carbon due to nonpolypeptidic compounds, indicating the presence of either uronic acids in the complex structure of pectic polysaccharides or of polyphenolic esters. This structural and chemical information and its relationship with the experimental procedures indicate that proteins alone cannot be used as a realistic model for the macromolecules forming the adsorption layer of champagne. Polysaccharides, the other major macromolecular components of champagne wine, are assembled with proteins at the interfaces, in agreement with the heterogeneous character of the adsorbed layer at interfaces. PMID:19813745

Aguié-Béghin, V; Adriaensen, Y; Péron, N; Valade, M; Rouxhet, P; Douillard, R

2009-11-11

38

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

OpenAIRE

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 ...

Asghari, F.; Jahanshahi, M.; Ghoreyshi, A. A.

2012-01-01

39

Porosity in plasma electrolytic oxide coatings  

International Nuclear Information System (INIS)

Plasma electrolytic oxide coatings are generally assumed to be almost fully dense. However, evidence is presented here for the presence of sub-micrometre, surface-connected porosity in such coatings, on aluminium alloys, at levels of the order of 20%. This evidence comes from densitometry, mercury porosimetry, helium pycnometry, BET adsorption measurements and high-resolution scanning electron microscopy. The very fine scale of the porosity (pore diameter ?10 to 100 nm), coupled with severe difficulties in making unambiguous microstructural observations, may account for the failure to detect this feature previously. It is pointed out that various measured properties, such as Young's modulus and thermal conductivity, are consistent with the presence of these relatively high porosity levels. Various other observed characteristics can also be explained on this basis. Finally, a possible mechanistic origin for the porosity is proposed

40

The development of composite adsorbent for organic waste decomposion treatment and chemical recovery  

Energy Technology Data Exchange (ETDEWEB)

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

Gun, Shul Yong; Jung, Kyeong Taek; Kim, Hyung Tae; Kim, Ki Wook; Kim, Hyun Jong [Yonsei University, Seoul (Korea); Kim, Jong [Konyang University, Nonsan (Korea)

1999-01-01

41

Removal of hydrogen sulfide at ambient conditions on cadmium/GO-based composite adsorbents.  

Science.gov (United States)

Cadmium-based materials with various hydroxide to carbonate ratios and their composites with graphite oxide were synthesized by a fast and simple precipitation procedure and then used as H2S adsorbents at ambient conditions in the dark or upon a visible light exposure. The structural properties and chemical features of the adsorbents were analyzed before and after hydrogen sulfide adsorption. The results showed that the high ratio of hydroxide to carbonate led to an improved H2S adsorption capacity. In moist conditions cadmium hydroxide was the best adsorbent. Moreover, it showed photoactive properties. While the incorporation of a graphene-based phase slightly decreased the extent of the improvement in the H2S adsorption capacity in moist conditions caused by photoactivity, its presence in the composites enhanced the performance in dry conditions. This was linked to photoactivity of CdS that can split H2S resulting in the formation of water in the system. The graphene-based phase enhanced the electron transfer and delayed the recombination of photoinduced charges. Carbonate-based materials showed a very good adsorption capacity in dark conditions in the presence of moisture. Upon the light exposure, CdS likely photocatalyzes the reduction of carbonate ions to formates/formaldehydes. Their deposition on the surface limits the number of sites available to H2S adsorption. PMID:25792480

Florent, Marc; Wallace, Rajiv; Bandosz, Teresa J

2015-06-15

42

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

43

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)

44

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 56 d. The adsorbed uranium was eluted from the adsorbent with 0.5 N NaHCO3-0.5N Na2CO3 soln. at 700C. The elution recovery was 97.4% for 35 h. The uranium contained in the eluate was concentrated twenty times as much as in the anion exchange process, 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 pure 2UO2.NH3.3H2O by X-ray diffraction method and X-ray fluorometry. (author)

45

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

46

Densification of mixed-oxide coated silicon nitride powders  

Energy Technology Data Exchange (ETDEWEB)

Powder coating is being developed as a method of incorporating sintering additives into a ceramic powder. This procedure has been explored in the case of Si{sub 3}N{sub 4} powders coated with mixed oxide layers of MgO-Al{sub 2}O{sub 3}. Mixed oxide coatings have been deposited on the surface of silicon nitride powders, with the aim of simulating grain-boundary eutectic liquid compositions for the purpose of achieving low-temperature densification. The effectiveness of the powder coating technique has been evaluated by comparing the powder properties, densification behaviour, and microstructure of coated Si{sub 3}N{sub 4} powders with identical powders in which the additive oxide has been added in particulate form. It is concluded that the powder coating technique is an excellent method of homogeneously incorporating minor amounts of sintering additive into a powder. The coated powder exhibited improved homogeneity, and gave good green compact density, high green strength, and faster densification rate. Moreover, coated powders densified more easily by pressureless sintering and showed a more homogeneous microstructure and faster densification rates, compared with materials prepared using mixed oxide powders. (orig.) 8 refs.

Tatli, Z.; Thompson, D.P. [Newcastle upon Tyne Univ. (United Kingdom). Dept. of Mechanical Materials and Manufacture Engineering; Errington, R.J. [Dept. of Chemistry Univ. of Newcastle, Newcastle upon Tyne (United Kingdom)

1997-12-31

47

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.

48

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

Directory of Open Access Journals (Sweden)

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

49

Characterization of adsorbed silane on fillers used in dental composite restoratives and its effect on composite properties.  

Science.gov (United States)

The purpose was to study the effect of silane treatment of fillers on viscosity, flexural strength, and hydrolytic degradation of experimental dental composite resins fabricated with these fillers. The fillers consisted of a mixture of barium glass and amorphous silica. The resin was mainly based on ethoxylated bisphenol A dimethacrylate and polycarbonate dimethacrylate. The adsorption of silane on the filler surface was characterized by FTIR. There was significant correlation between the adsorbed silane on filler surface and the silane concentration in silane/methanol solution used for filler treatment. The silane concentration varied from 0.75 to 14% by weight. An increase in silane concentration led to a decrease in viscosities of the corresponding composite resins. The flexural strengths of composites with silanated fillers were greater than that of composites with unsilanated fillers: however, no significant difference was found between the flexural strengths of various silanated groups. The resistance to hydrolytic degradation of different composites increased when the fillers were treated with silane and was the highest at 1.1% silane. PMID:17268866

Karmaker, A; Prasad, A; Sarkar, N K

2007-06-01

50

Ultimate selenium(IV) monitoring and removal from water using a new class of organic ligand based composite adsorbent.  

Science.gov (United States)

This work reports the selenium (Se(IV)) detection and removal from water by ligand functionalized organic-inorganic based novel composite adsorbent. The composite adsorbent was prepared by direct immobilization of N,N'-di(3-carboxysalicylidene)-3,4-diamino-5-hydroxypyrazole onto the mesoporous silica monolith. The adsorbent exhibited distinct color change in the presence of various concentrations of Se(IV). This was characterized by UV-vis spectroscopy, and the color change was observed by naked-eye observation. The detection limit was determined to be 1.14?g/L. The effect of solution pH, interferential metal ions, contact time, initial Se(IV) concentration, and adsorbent regeneration were evaluated. The maximum sorption capacity was determined based on the initial concentration. The data fitted well to the Langmuir isotherm model, and the maximum Se(IV) sorption capacity was 111.12mg/g. The presence of diverse competing ions did not affect the Se(IV) sorption capacity, and the adsorbent had almost no sorption capacity for these coexisting ions, which suggests the high selectivity to Se(IV) ions. The adsorbed Se(IV) was eluted with suitable eluent (0.10M NaOH) and simultaneously regenerated into the initial form for the next operation. The excellent reusability of the adsorbent was justified after eight consecutive sorption-elution-regeneration cycles. The proposed adsorbent is cost-effective and environmentally friendly and a potential candidate for treatment of water containing Se(IV). PMID:25771216

Awual, Md Rabiul; Yaita, Tsuyoshi; Suzuki, Shinichi; Shiwaku, Hideaki

2015-06-30

51

Electrochemical combustion of indigo at ternary oxide coated titanium anodes  

Directory of Open Access Journals (Sweden)

Full Text Available The film of iridium and tin dioxides doped with antimony (IrO2-SnO2–Sb2O5 deposited on a Ti substrate (mesh obtained by Pechini method was used for the formation of ·OH radicals by water discharge. Detection of ·OH radicals was followed by the use of the N,N-dimethyl-p-nitrosoaniline (RNO as a spin trap. The electrode surface morphology and composition was characterized by SEM-EDS. The ternary oxide coating was used for the electrochemical combustion of indigo textile dye as a model organic compound in chloride medium. Bulk electrolyses were then carried out at different volumetric flow rates under galvanostatic conditions using a filter-press flow cell. The galvanostatic tests using RNO confirmed that Ti/IrO2-SnO2-Sb2O5 favor the hydroxyl radical formation at current densities between 5 and 7 mA cm-2, while at current density of 10 mA cm-2 the oxygen evolution reaction occurs. The indigo was totally decolorized and mineralized via reactive oxygen species, such as (·OH, H2O2, O3 and active chlorine formed in-situ at the Ti/IrO2-SnO2-Sb2O5 surface at volumetric flow rates between 0.1-0.4 L min-1 and at fixed current density of 7 mA cm-2. The mineralization of indigo carried out at 0.2 L min-1 achieved values of 100 %, with current efficiencies of 80 % and energy consumption of 1.78 KWh m-3.

María I. León

2014-12-01

52

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

53

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

54

Effects of temperature and adsorbates on the composition profile of Pt-Rh nanocatalysts A comparative study  

CERN Document Server

Monte-Carlo simulation technique has been used to investigate the effect of temperature and adsorbed gases on the composition profile of unsupported Pt-Rh nanocatalysts. For a 2406 atom fcc cubo-octahedral Pt$_{\\rm{}50}$Rh$_{\\rm{}50}$ nanocatalyst the shell-wise composition for all the eight shells has been simulated. For the temperatures 700 K, 1000 K and 1300 K, the top shell of clean Pt-Rh nanocatalysts is found to be mildly Pt-enriched, while the second shell is Pt-depleted. The Pt concentration of the top shell shows a maximum at T = 1000 K. In presence of a quarter monolayer of adsorbed oxygen the top shell shows Rh enrichment, while all the other shells show Pt-enrichment. This is true for all the three temperatures for which the composition profiles have been studied.

De Sarkar, A; Sarkar, Abir De; Khanra, Badal C.

2001-01-01

55

Engineering the surface of a new class of adsorbents: Metal-organic framework/graphite oxide composites.  

Science.gov (United States)

This paper reviews the results of several prior studies to highlight how the concept of the metal-organic framework/graphite oxide (MOF/GO) composites was developed towards their application as separation media for small molecule gases at ambient conditions. The studies are analyzed from a surface engineering standpoint. The MOF/GO composites have been developed considering both the advantages and drawbacks of the composite components: MOF provided a high porosity and reactive centers and GO a dense array of carbon atoms to increase dispersive interactions. The resulting materials showed a significant enhancement in porosity owing to the formation of pores at the interface of GO and MOF crystals. GO oxygen groups were identified as nucleation sites for the formation of the MOF crystals. Other heteroatoms like N also contributed to that effect and could positively enhance the composites structural/chemical heterogeneity. That heterogeneity governed the excellent performance of the composites as reactive adsorbents of NH3, H2S, NO2 and physical adsorbents of CO2 at ambient conditions. While the MOF structure collapsed upon exposure to toxic gases, it was preserved after CO2 adsorption indicating the recyclability of these materials. Systematic studies of the composite properties showed that such factors as the GO level of oxidation, flake sizes of a graphite precursor and the geometry of MOF crystals are of paramount importance dictating the final morphology of the composite. The properties of the composites make them potentially suitable for gas sensing or energy harvesting. PMID:25234622

Petit, Camille; Bandosz, Teresa J

2015-06-01

56

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

57

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

58

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.

59

Molecular and isotopic compositions of gases adsorbed to near surface sediments at Starunia palaeontological site and vicinity (Carpathian region, Ukraine)  

OpenAIRE

The near-surface geochemical survey of gases desorbed from sediment samples was carried out in the area of an abandoned ozokerite mine in Starunia, where remnants of mammoth and three woolly rhinoceroses and one almost completely preserved rhinoceros carcass were discovered in 1907 and 1929. Numerous hydrocarbon seeps (gas and oil "eyes") occur on the surface of the study area. Analyses of molecular and stable carbon isotope compositions of adsorbed gases were carried out in two variants. The...

Dzieniewicz, Marek; Sechman, Henryk; Kotarba, Maciej J.

2009-01-01

60

Preparation of Nano Iron Oxide Coated Activated Sludge Granules and its Adsorption Properties for Cd (II Ions in Aqueous Solutions  

Directory of Open Access Journals (Sweden)

Full Text Available The purpose of this study is Preparation of nano iron oxide coated activated sludge granules and its adsorption properties for Cd (II ions in aqueous solutions. Activated sludge as biosorbent was modified using nano iron oxide coating and examined for removal of cadmium ions from aqueous solutions. The effect of parameters including amount of coating, contact time, solution pH, initial Cd concentration and adsorbent dosage was evaluated in batch experiments. The results showed that percentage removal of 91.6 was achieved by using modified sludge at alkaline pH 9 and contact time 120 min. The uptake of cadmium was best described by Langmuir-Freundlich isotherms. The kinetic study revealed that Cd (II adsorption was in agreement with pseudo second-order equation. The Cd (II loaded and unloaded granules were analyzed using Scanning Electron Microscopy (SEM and Fourier transform infrared spectroscopy (FTIR. Based on the obtained results, the modified activated sludge granules with nano iron oxide are an efficient adsorbent for removal of cadmium ions as inorganic water and wastewater pollutant.

Muhammad Hashemifar

2014-05-01

61

Effects of MAR-M247 substrate (modified) composition on coating oxidation coating/substrate interdiffusion. M.S. Thesis. Final Report; [protective coatings for hot section components of gas turbine engines  

Science.gov (United States)

The effects of gamma+gamma' Mar-M247 substrate composition on gamma+beta Ni-Cr-Al-Zr coating oxidation and coating/substrate interdiffusion were evaluated. These results were also compared to a prior study for a Ni-Cr-Al-Zr coated gamma Ni-Cr-Al substrate with equivalent Al and Cr atomic percentages. Cyclic oxidation behavior at 1130 C was investigated using change in weight curves. Concentration/distance profiles were measured for Al, Cr, Co, W, and Ta. The surface oxides were examined by X-ray diffraction and scanning electron microscopy. The results indicate that variations of Ta and C concentrations in the substrate do not affect oxidation resistance, while additions of grain boundary strengthening elements (Zr, Hf, B) increase oxidation resistance. In addition, the results indicate that oxidation phenomena in gamma+beta/gamma+gamma' Mar-M247 systems have similar characteristics to the l gamma+beta/gamma Ni-Cr-Al system.

Pilsner, B. H.

1985-01-01

62

Ultrathin multifunctional oxide coatings for lithium ion batteries  

Energy Technology Data Exchange (ETDEWEB)

Ultrathin oxide coatings are demonstrated to offer multiple functions for improving the cycling performance of lithium ion batteries. The coatings can serve as an artificial solid electrolyte interphase layer, which significantly suppresses electrolyte decomposition as well as mitigates mechanical degradation. Structure modification is critical for increasing the ion conductivity, and therefore leads to improved current efficiency. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Xiao, Xingcheng [General Motors Global Research and Development Center, Warren, MI (United States); Lu, Peng [Trison Business Solutions, Inc., Le Roy, NY (United States); Ahn, Dongjoon [University of Kentucky, Lexington, KY (United States)

2011-09-08

63

Versatile wet deposition techniques for functional oxide coatings  

OpenAIRE

Functional oxide coatings are essential components in a variety of today's technical products and developments, but often applications are limited by the low flexibility and the high cost of the vapor phase deposition techniques used at present. Wet chemical processes based on the sol-gel and nanoparticle approaches can provide desired alternatives for a large number of such applications. This is shown for the high temperature sol-gel processing and the low-temperature nanoparticle approach w...

Aegerter, Michel A.; Pu?tz, Jo?rg; Gasparro, Guido; Al-dahoudi, Naji

2004-01-01

64

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

65

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.

66

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

67

Arsenic Removal from Aqueous Solutions Using Fe3O4-HBC Composite: Effect of Calcination on Adsorbents Performance  

Science.gov (United States)

The presence of elevated concentration of arsenic in water sources is considered to be health hazard globally. Calcination process is known to change the surface efficacy of the adsorbent. In current study, five adsorbent composites: uncalcined and calcined Fe3O4-HBC prepared at different temperatures (400°C and 1000°C) and environment (air and nitrogen) were investigated for the adsorptive removal of As(V) and As(III) from aqueous solutions determining the influence of solution's pH, contact time, temperature, arsenic concentration and phosphate anions. Characterizations from FTIR, XRD, HT-XRD, BET and SEM analyses revealed that the Fe3O4-HBC composite at higher calcination temperature under nitrogen formed a new product (fayalite, Fe2SiO4) via phase transformation. In aqueous medium, ligand exchange between arsenic and the effective sorbent site (?=?FeOOH) was established from the release of hydroxyl group. Langmuir model suggested data of the five adsorbent composites follow the order: Fe3O4-HBC-1000°C(N2)>Fe3O4-HBC (uncalcined)>Fe3O4-HBC-400°C(N2)>Fe3O4-HBC-400°C(air)>Fe3O4-HBC-1000°C(air) and the maximum As(V) and As(III) adsorption capacities were found to be about 3.35 mg g?1 and 3.07 mg g?1, respectively. The adsorption of As(V) and As(III) remained stable in a wider pH range (4–10) using Fe3O4-HBC-1000°C(N2). Additionally, adsorption data fitted well in pseudo-second-order (R2>0.99) rather than pseudo-first-order kinetics model. The adsorption of As(V) and As(III) onto adsorbent composites increase with increase in temperatures indicating that it is an endothermic process. Phosphate concentration (0.0l mM or higher) strongly inhibited As(V) and As(III) removal through the mechanism of competitive adsorption. This study suggests that the selective calcination process could be useful to improve the adsorbent efficiency for enhanced arsenic removal from contaminated water. PMID:24967645

Baig, Shams Ali; Sheng, TianTian; Sun, Chen; Xue, XiaoQin; Tan, LiSha; Xu, XinHua

2014-01-01

68

X-ray Diffraction Studies of the Structure and Thermochemistry of Alkaline-Earth Oxide-Coated Thermionic Cathodes  

Science.gov (United States)

NASA LeRC has a broad, active cathode technology development program in which both experimental and theoretical studies are being employed to further development of thermionic cathodes for use as electron sources in vacuum devices for communications and other space applications. One important type of thermionic cathode under development is the alkaline-earth oxide-coated (BaO, SrO, CaO) cathode. Significant improvements in the emission characteristics of this cathode have been obtained through modification of the chemical composition and morphology of the oxide coating, with the best result thus far coming from the addition of In2O3 and Sc2O3. Whereas the In2O3 produces a finer, more uniform particle structure, the exact chemical state and role of the Sc2O3 in the emission enhancement is unknown. The purpose of this cooperative agreement is to combine the studies of the surface chemistry and electron emission at NASA LeRC of chemically modified oxide coatings with a study of the thermochemistry and crystal structure using X-ray diffraction equipment and expertise at Clark Atlanta University (CAU). The study at CAU is intended to provide the description and understanding of the structure and thermochemistry needed for further improvement and optimization of the modified coatings. A description of the experimental procedure, preliminary X-ray diffraction test results, together with the design of an ultrahigh vacuum chamber necessary for high temperature thermochemistry studies will be presented.

Karikari, E. K.; Bassey, E.; Wintucky, Edwin G.

1998-01-01

69

Electrochemical properties of inorganic nanoporous oxide coated electrodes  

Science.gov (United States)

The ability to produce clean water and produce and store clean energy is essential to society. Hence, technologies that facilitate clean energy and clean water are of great importance. This study focused on utilizing nanoporous insulating oxide materials to alter the chemistry at the electrode/electrolyte interface to improve the performance of a number of clean energy and clean water technologies. Here we have shown that applying a thin-film of SiO2 nanoparticles to an electrochemical capacitor electrode can increase the energy storage capacity by up to 50% at high power ratings. We have developed a geometric model to describe the coating of the porous electrode to explain the increased performance at high power ratings. We have also shown that the coated electrochemical capacitor exhibits a higher capacitance when normalized to BET surface area, suggesting that the coated surface is behaving fundamentally differently than the uncoated surface. We attribute the increase in capacitance to the inherent surface potential of the oxide coating and have shown that if we alter the surface potential of the oxide, we can in turn alter the electrochemical capacitance. In addition, we have determined that when used in capacitive deionization systems, these coatings can increase ion removal and accelerate regeneration, allowing for higher efficiency and less waste water. We have demonstrated that a nanoporous oxide coating can increase the gas production rate and lower the overpotential of the hydrogen evolution reaction via water electrolysis on both stainless steel and carbon electrodes. In addition, this work presents data on utilizing nanoporous oxide coatings on Li-Ion battery cathodes to improve high temperature capacity fade. We also introduce a novel thin-film battery/electrochemical capacitor hybrid device, which can improve the performance of simple thin-film batteries.

Leonard, Kevin C.

70

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 (8.1 emu g(-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

71

Microstructure change and deuterium permeation behavior of erbium oxide coating  

International Nuclear Information System (INIS)

Deuterium permeation measurements and microstructure analyses on erbium oxide coating deposited by filtered arc deposition have been investigated. It is found that the permeation suppression efficiency is proportional to the coating thickness in case of the coating without pores and cracks reaching to the substrate. A phase transformation of the coating during the permeation measurements at 773-973 K has been identified. A grain growth of the coating has occurred during the measurements and permeation suppression efficiency have enhanced according to the grain size. It is suggested that deuterium permeation through the coating is mainly dominated by the crystal grain diffusion.

72

Fabrication of electrically conductive metal oxide coatings by reactive ion plating  

International Nuclear Information System (INIS)

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

73

As(V) adsorption onto nanoporous titania adsorbents (NTAs): effects of solution composition.  

Science.gov (United States)

This study has focused on developing two nanoporous titania adsorbents (NTA) to enhance removal efficiency of adsorption process for As(V) by characterizing the effects of pH and phosphate concentration on their sorption capacities and behaviors. One type of adsorbent is a mesoporous titania (MT) solid phase and the other is group of a highly ordered mesoporous silica solids (SBA-15) that can incorporate different levels of reactive titania sorption sites. Microscopic analysis showed that Ti((25))-SBA-15 (Ti/SBA=0.25 g/g) had titania nanostructured mesopores that do not rupture the highly ordered hexagonal silica framework. However, MT has disordered, wormhole-like mesopores that are caused by interparticle porosity. Adsorption experiments showed that Ti((25))-SBA-15 had a greater sorption capacity for As(V) than did Ti((15))-SBA-15 or Ti((35))-SBA-15 and the amount of As(V) adsorbed generally decreased as pH increased. Higher removal of As(V) was observed with Ti((25))-SBA-15 than with MT at pH 4, but MT had higher removals at higher pH (7, 9.5), even though MT has a lower specific surface area. However, in the presence of phosphate, MT showed higher removal of As(V) at low pH rather than did Ti((25))-SBA-15. As expected, the NTAs showed very fast sorption kinetics, but they followed a bi-phasic sorption pattern. PMID:22727482

Han, Dong Suk; Batchelor, Bill; Park, Sung Hyuk; Abdel-Wahab, Ahmed

2012-08-30

74

Carbon and functionalized graphene oxide coated vanadium oxide electrodes for lithium ion batteries  

Energy Technology Data Exchange (ETDEWEB)

Carbon- and graphene oxide-coated vanadium oxide nanomaterials were synthesized from a VOSO{sub 4} sol using a hydrothermal method to prepare electrodes for lithium ion batteries. The synthesized materials were characterized using x-ray diffraction, scanning electron microscopy and transmission electron microscopy. Electrochemical results show that graphene oxide coated vanadium oxide electrodes have higher capacity than the carbon coated ones.

Reddy Channu, V.S., E-mail: chinares02@gmail.com [Texas Biochemicals, Inc, College Station, TX 77840 (United States); Ravichandran, D. [Texas Biochemicals, Inc, College Station, TX 77840 (United States); Rambabu, B. [Solid State Ionics and Surface Sciences Lab, Department of Physics, Southern University and A and M College, Baton Rouge, LA 70813 (United States); Holze, Rudolf [Institut für Chemie, AG Elektrochemie, Technische Universität Chemnitz, Chemnitz D-09107 (Germany)

2014-06-01

75

Carbon and functionalized graphene oxide coated vanadium oxide electrodes for lithium ion batteries  

International Nuclear Information System (INIS)

Carbon- and graphene oxide-coated vanadium oxide nanomaterials were synthesized from a VOSO4 sol using a hydrothermal method to prepare electrodes for lithium ion batteries. The synthesized materials were characterized using x-ray diffraction, scanning electron microscopy and transmission electron microscopy. Electrochemical results show that graphene oxide coated vanadium oxide electrodes have higher capacity than the carbon coated ones.

76

Novel nanosized adsorbing sulfur composite cathode materials for the advanced secondary lithium batteries  

Energy Technology Data Exchange (ETDEWEB)

A novel conductive sulfur-containing nanocomposite cathode material was synthesized by heating the mixture of sublimed sulfur and multi-walled carbon nanotubes (MWNTs) in certain conditions. The cathode with MWNTs-sulfur nanocomposite (MSN) material shows the improvement of not only the charge-discharge capacity but also cycle durability. From the results, it is confirmed that the MWNTs shows a vital role on adsorbing sublimed sulfur and the polysulfides within the cathode and is an excellent electric conductor for the lithium-sulfur rechargeable system. It can effectively prevent the shuttle behavior of the lithium-sulfur battery. (authors)

Zheng, W.; Liu, Y.W.; Zhang, C.F. [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China); Jiangmen JJJ Battery Co., Ltd, Jiangmen 529000 (China); Hu, X.G. [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China)

2006-01-05

77

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

78

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

Energy Technology Data Exchange (ETDEWEB)

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 produced waters, Ba and Ra are not preferentially adsorbed.

Hanor, Jeffrey S. [Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA 70803 (United States)], E-mail: hanor@lsu.edu

2007-10-15

79

Preparation and properties of cobalt oxides coated carbon fibers as microwave-absorbing materials  

International Nuclear Information System (INIS)

Cobalt oxides/carbon fibers (CoOx/CFs) composites were synthesized by thermal oxidation of cobalt coated carbon fibers (Co/CFs). The scanning electron microscopy images and X-ray diffraction pattern indicate that the layers are about 0.7 ?m and composed of Co3O4 and CoO (CoOx), the preferred condition for preparation of CoOx/CFs composites is to anneal Co/CFs precursors at 350 deg. C for 3 h in air. The coercivity, saturation magnetization and residual magnetization of the CoOx/CFs composites are 464.8 Oe, 10.62 emu/g and 2.21 emu/g, respectively. The reflectivity of cobalt oxides coated carbon fibers (1.11-5.12 mm in thickness) is less than -10 dB over the working frequency range of 4.04-18.00 GHz and less than -20 dB over 11.54-14.77 GHz. The lowest reflectivity is -45.16 dB at 13.41 GHz when the thickness is 1.50 mm.

80

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

OpenAIRE

[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

81

Nano copper oxide-incorporated mesoporous carbon composite as multimode adsorbent for selective isolation of hemoglobin.  

Science.gov (United States)

Assembly of nano-objects with tunable size, morphology and function into integrated nanostructures is critical for the development of a novel nanosystem in adsorption, sensing and drug/gene delivery. We demonstrate herein the fabrication of ordered mesoporous carbon by assembling uniform and highly dispersed copper-oxide (CuxOy) nanoparticles into the mesopores via evaporation of solvent from the mixture of triblock copolymer, carbon source and metal nitrate hydrate. The ordered 2D hexagonal mesoporous carbon composite possesses a large surface area of 580.8 cm(2)/g, a uniform pore size of 5.4 nm, a large pore volume of 0.64 cm(3)/g and a high metal content of 3.32 wt %. The mesoporous composite exhibits excellent adsorption selectivity and high adsorption capacity to hemoglobin (Hb) under the synergistic effect of hydrophobic and metal-affinity interactions as well as size exclusion. This facilitates multimode adsorption of hemoglobin fitting Langmuir adsorption model and offers an adsorption capacity of 1666.7 mg g(-1) for hemoglobin. The mesoporous composite is used for the isolation of hemoglobin from human whole blood with high purity. It demonstrates the potential of the copper-oxide nanoparticle-embedded mesoporous carbon composite in selective isolation/removal of specific protein species from biological sample matrixes. PMID:25692225

Zhang, Yang; Xing, Li-Gang; Chen, Xu-Wei; Wang, Jian-Hua

2015-03-11

82

CuFe2O4/activated carbon composite: a novel magnetic adsorbent for the removal of acid orange II and catalytic regeneration.  

Science.gov (United States)

CuFe2O4/activated carbon magnetic adsorbents, which combined the adsorption features of activated carbon with the magnetic and the excellent catalytic properties of powdered CuFe2O4, were developed using a simple chemical coprecipitation procedure. The prepared magnetic composites can be used to adsorb acid orange II (AO7) in water and subsequently, easily be separated from the medium by a magnetic technique. CuFe2O4/activated carbon magnetic adsorbents with mass ratio of 1:1, 1:1.5 and 1:2 were prepared. Magnetization measurements, BET surface area measurements, powder XRD and SEM were used to characterize the prepared adsorbents. The results indicate that the magnetic phase present is spinel copper ferrite and the presence of CuFe2O4 did not significantly affect the surface area and pore structure of the activated carbon. The adsorption kinetics and adsorption isotherm of acid orange II (AO7) onto the composites at pH 5.2 also showed that the presence of CuFe2O4 did not affect the adsorption capacity of the activated carbon. The thermal decomposition of AO7 adsorbed on the activated carbon and the composite was investigated by in situ FTIR, respectively. The results suggest that the composite has much higher catalytic activity than that of activated carbon, attributed to the presence of CuFe2O4. The variation of the adsorption capacity of the composites after several adsorption-regeneration cycles has also been studied. PMID:17397903

Zhang, Gaosheng; Qu, Jiuhui; Liu, Huijuan; Cooper, Adrienne T; Wu, Rongcheng

2007-06-01

83

Novel transparent conducting sol-gel oxide coatings  

International Nuclear Information System (INIS)

This work focuses on the preparation of novel ternary transparent conducting oxide coatings on glass by the sol-gel method. The coatings were deposited by spin-coating from solutions of appropriate metal precursors and heat-treated at different heat-treatment procedures. An increase in electrical conductivity was achieved by a final forming gas treatment. Best electrical and optical properties have been obtained for coatings of crystalline Zn2SnO4, Zn3In2O6 and Zn5In2O8 and X-ray amorphous ZnSnO3 with resistivities in the order of 10-2-10-1 ? cm, an average transmission in the visible of 85% and an average surface roughness of ? 1 nm. ZnGa2O4 and GaSbO4 coatings showed no electrical conductivity. For Zn2SnO4 coatings, a restricted crystallite growth was observed probably due to phase segregation effects. Electrical properties of coatings in the system ZnO-In2O3 were interpreted on the basis of the percolation theory

84

The utilization of welding technologies in the treatment of ZrO2-based oxide coatings - the phase and structural aspects of remelting  

International Nuclear Information System (INIS)

Improving the method of remelting plasma-sprayed oxide coatings is done chiefly based on laser technologies, which is indicated by numerous studies published in both domestic and foreign specialist magazines. In the case of present study, an alternative method of remelting has been applied, which uses welding sources of heat. Because of thermophysical and electrical properties of oxide compositions used, a modification of the welding stand turned out to be necessary, which involved primarily equipping it with an additional, independent electrode and nozzle unit. The application of the above solution provided a capability of using the thermal energy of the arc, without engaging the coating in the process of arc generation and stabilization. The structural and phase effects of remelting oxide coatings by using the developed unit is presented in this article. (author)

85

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

86

Hierarchical MWCNTs/Fe3O4/PANI magnetic composite as adsorbent for methyl orange removal.  

Science.gov (United States)

Multi-wall carbon nanotubes (MWCNTs) decorated with Fe3O4 nanoparticles (MWCNTs/Fe3O4) were modified by polyaniline (PANI). The adsorption kinetics of methyl orange (MO) on MWCNTs/Fe3O4/PANI could be fitted well by the pseudo-second-order model. The adsorption of MO on MWCNTs/Fe3O4/PANI was strongly dependent on pH values. The Langmuir isotherm model fitted MO adsorption isotherm better than the Freundlich model. The hierarchical MWCNTs/Fe3O4/PANI showed high adsorption capacity toward ionic dyes (446.25mgg(-1) for MO and 417.38mgg(-1) for Congo red (CR)). The nitrogen-containing functional groups of PANI decorated on MWCNTs/Fe3O4/PANI contributed to many effective adsorption sites and thus increased the adsorption capacity toward MO and CR. Moreover, PANI prevented Fe3O4 nanoparticles from dissolution, and hence improved the stability of MWCNTs/Fe3O4/PANI in solution. The experimental results showed that the MWCNTs/Fe3O4/PANI composite was a promising magnetic material for the preconcentration and separation of ionic dye pollutants from aqueous solutions in environmental pollution cleanup. PMID:25819003

Zhao, Ying; Chen, Hongli; Li, Jie; Chen, Changlun

2015-07-15

87

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

OpenAIRE

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

88

Corrosion evaluation of zirconium doped oxide coatings on aluminum formed by plasma electrolytic oxidation.  

Science.gov (United States)

The plasma electrolytic oxidation (PEO) of aluminum in sodium tungstate (Na(2)WO(4) · (2)H(2)O) and Na(2)WO(4) · (2)H(2)O doped with Zr was analyzed in order to obtain oxide coatings with improved corrosion resistance. The influence of current density in PEO process and anodization time was investigated, as well as the influence of Zr, with the aim to find out how they affect the chemical content, morphology, surface roughness, and corrosion stability of oxide coatings. It was shown that the presence of Zr increases the corrosion stability of oxide coatings for all investigated PEO times. Evolution of EIS spectra during the exposure to 3% NaCl, as a strong corrosive agent, indicated the highest corrosion stability for PEO coating formed on aluminum at 70 mA/cm(2) for 2 min in a zirconium containing electrolyte. PMID:25125114

Bajat, Jelena; Miškovi?-Stankovi?, Vesna; Vasili?, Rastko; Stojadinovi?, Stevan

2014-01-01

89

Manganese oxide-coated redox bars as an indicator for reducing soil conditions  

Science.gov (United States)

Field identification of reducing soil conditions is of concern not only for soil pedogenesis but also for nutrient and pollutant dynamics in soils. We manufactured manganese (Mn) oxide-coated polyvinyl chloride (PVC) bars and proved their suitability for identification of reducing soil conditions in both the laboratory and field. Birnessite (?-MnO2) was synthesized according to a recently published method and was coated onto white PVC bars. We used microcosm devices with adjusted redox potentials (EH) to distinguish the onset and intensity of depletion patterns along the Mn oxide-coating and soil column experiments combined with field application to validate the enhanced removal of Mn against Fe oxide-coated bars under anaerobe soil conditions. Field application was performed at a site with shallow and strongly fluctuating water tables where water table depth and soil temperature were monitored. Three microcosm experiments adjusted to oxidizing (EH ~500 mV, pH 7), weakly reducing (EH ~175 mV, pH 7) and moderately reducing conditions (EH ~25 mV, pH 7) showed depending on the EH no, slight, or intense removal of the Mn oxide-coating, respectively. Moreover, the removal of Mn oxide (225 mm2 d-1) in soil column experiments exceeded the removal of Fe oxide (118 mm2 d-1). The enhanced removal of the Mn oxide-coating was also found under anaerobe conditions in field application. Consequently, identifying of reducing conditions in soils by Mn oxide-coated bars is possible. We recommend using this methodology for short-term monitoring, e.g. on weekly basis, since tri- and tetravalent Mn is the preferred electron acceptor compared with trivalent Fe.

Dorau, Kristof; Mansfeldt, Tim

2014-05-01

90

Scandium oxide coated polycrystalline tungsten studied using emission microscopy and photoelectron spectroscopy  

International Nuclear Information System (INIS)

Thermionic electron emission from 200 to 500 nm thick coatings of scandium oxide on tungsten foil have been examined in thermionic emission microscopy, spectroscopic photoelectron microcopy, synchrotron radiation and ultraviolet photoelectron spectroscopy (UPS). A clear dependence of the scandium oxide-W electron yield on the grain orientation of the polycrystalline tungsten is observed in thermionic emission and photoelectron emission. -- Highlights: ? Polycrystalline tungsten imaged with spectroscopic thermionic emission microcopy. ? Scandium oxide coated tungsten grains observed during thermionic emission. ? Direct visualization of the surface electron yield due to oxide coatings. ? Findings related to thermionic cathodes.

91

Studies on anodic oxide coating with low absorptance and high emittance on aluminum alloy 2024  

Energy Technology Data Exchange (ETDEWEB)

Anodization of AA 2024 in sulfuric acid bath containing glycerol, lactic acid and ammonium metavenadate has been studied to develop white anodic oxide coating. Investigation on the influence of various operating parameters - coating thickness, current density and ammonium metavenadate concentration on the optical properties was carried out to optimize the process. Infrared, atomic absorption spectroscopic techniques and scanning electron micrograph were used to characterize the coating. The obtained oxide coating provides a ratio of solar absorptance ({alpha}) to infrared emittance ({epsilon}), as low as 0.2. The optical properties and hardness values measured under optimum experimental conditions support its use as a thermal control coating.

Siva Kumar, C. [Department of Post-graduate studies in Chemistry, Central College, Bangalore (India); Sharma, A.K. [Thermal Process Section, ISRO Satellite Centre, Vimanapura Post, Bangalore (India); Mahendra, K.N.; Mayanna, S.M. [Department of Post-graduate studies in Chemistry, Central College, Bangalore (India)

2000-01-01

92

Mechanism of formation of humus coatings on mineral surfaces 3. Composition of adsorbed organic acids from compost leachate on alumina by solid-state 13C NMR  

Science.gov (United States)

The adsorption of compost leachate DOC on alumina is used as a model for elucidation of the mechanism of formation of natural organic coatings on hydrous metal oxide surfaces in soils and sediments. Compost leachate DOC is composed mainly of organic acid molecules. The solid-state 13C NMR spectra of these organic acids indicate that they are very similar in composition to aquatic humic substances. Changes in the solid-state 13C NMR spectra of compost leachate DOC fractions adsorbed on alumina indicate that the DOC molecules are most likely adsorbed on metal oxide surfaces through a combination of polar and hydrophobic interaction mechanisms. This combination of polar and hydrophobic mechanism leads to the formation of bilayer coatings of the leachate molecules on the oxide surfaces.

Wershaw, R.L.; Llaguno, E.C.; Leenheer, J.A.

1996-01-01

93

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

94

Rusty nails adsorb trace plutonium from the environment  

International Nuclear Information System (INIS)

Discarded rusty iron objects in the environment adsorb trace plutonium mobilized by oxygenated surface waters (e.g. rain, snow melt). Radiochemical and mass spectrometric analysis of the surface oxide coating of modest collections of rusty nails retrieved from remote locations provides a global fallout plutonium signal of up to 2 x 1010 atoms of 239Pu per sample. The median 239Pu measurement for 10 samples from five locations was 2.82 x 109 atoms. The average 240Pu/239Pu atom ratio was 0.176 ± 0.012, consistent with the value accepted for global fallout. (author)

95

Structures and magnetic properties of iron- and cobalt-containing oxide coatings on an aluminum alloy formed in electrolytes via plasma electrolytic oxidation  

Science.gov (United States)

The effect of the nature of the supporting electrolyte in the composition of electrolytic suspensions containing dispersed particles of Fe(III) and Co(II) hydroxides, and of anodic and bipolar anodic-cathodic polarization on features of the formation, composition, and magnetic characteristics of oxide coatings is studied. In all cases, iron and cobalt are incorporated into the coatings and are concentrated predominantly in pores. The pores of the coatings include particles consisting of the reduced metals, presumably surrounded by oxide or hydroxide shells. The electrolyte composition affects the concentration and ratio of the metals in the particles. A correlation is observed between the ferro- or ferrimagnetism of the coatings and the content and ratio of cobalt and iron in the pores.

Rudnev, V. S.; Morozova, V. P.; Lukiyanchuk, I. V.; Adigamova, M. V.; Tkachenko, I. A.; Ustinov, A. Yu.; Kharitonskii, P. V.; Frolov, A. M.

2014-05-01

96

Measurement of thermal conductivity of the oxide coating on autoclaved monel-400  

International Nuclear Information System (INIS)

Thermal conductivity of the oxide coating on monel-400 has been measured by a direct method. The oxide coating is applied on an electrically conducting wire having stable characteristics. The wire is placed in a constant temperature bath and a constant direct current is passed through it. The wire gets heated and loses heat to the surrounding. Temperature is measured by considering it as a resistance thermometer. A convection heat transfer coefficient, which is difficult to measure experimentally but is involved in the analytical expression for thermal conductivity, is eliminated by connecting a second uncoated wire of a noble metal having similar surface finish as that of the coated wire in series with it. The accuracy of the method is nearly six percent. However, the method is not easily applicable for very thin (thickness <= 1?), highly porous coatings and materials having relatively large thermal conductivity. (M.G.B.)

97

A Comparative Study of Natural Fiber and Glass Fiber Fabrics Properties with Metal or Oxide Coatings  

Science.gov (United States)

Rapidly growing global demand for technical textiles industries is stimulated to develop new materials based on hybrid materials (yarns, fabrics) made from natural and glass fibres. The influence of moisture on the electrical properties of metal and metal oxide coated bast (flax, hemp) fibre and glass fibre fabrics are studied by electrical impedance spectroscopy and thermogravimetry. The bast fibre and glass fiber fabrics are characterized with electrical sheet resistance. The method for description of electrical sheet resistance of the metal and metal oxide coated technical textile is discussed. The method can be used by designers to estimate the influence of moisture on technical data of new metal coated hybrid technical textile materials and products.

Lusis, Andrej; Pentjuss, Evalds; Bajars, Gunars; Sidorovicha, Uljana; Strazds, Guntis

2015-03-01

98

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

99

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

100

Design, analysis, and fabrication of oxide-coated iridium/rhenium combustion chambers  

Science.gov (United States)

Iridium-coated rhenium (Ir/Re) combustion chambers provide high temperature, oxidation-resistant operation for radiation-cooled liquid-fueled rocket engines. A 22-N (5-lb(sub f)) chamber has been operated for 15 hours at 2200 C (4000 F) using nitrogen tetroxide/monomethyl hydrazine (NTO/MMH) propellant, with negligible internal erosion. The oxidation resistance of these chambers could be further increased by the addition of refractory oxide coatings, providing longer life and/or operation in more oxidizing and higher temperature environments. The oxide coatings would serve as a thermal and diffusion barrier for the iridium coating, lowering the temperature of the iridium layer while also preventing the ingress of oxygen and egress of iridium oxides. This would serve to slow the failure mechanisms of Ir/Re chambers, namely the diffusion of rhenium to the inner surface and the oxidation of iridium. Such protection could extend chamber lifetimes by tens or perhaps hundreds of hours, and allow chamber operation on stoichiometric or higher mixture ratio oxygen/hydrogen (O2/H2) propellant. Extensive thermomechanical, thermochemical, and mass transport modeling was performed as a key material/structure design tool. Based on the results of these analyses, several 22-N oxide-coated Ir/Re chambers were fabricated and delivered to NASA Lewis Research Center for hot-fire testing.

Jang, Q.; Tuffias, R. H.; Laferla, R.; Ghoniem, N. M.

1993-11-01

101

Aluminum oxide coating for post-growth photo emission wavelength tuning of indium phosphide nanowire networks  

Science.gov (United States)

Semiconductor-oxide nanostructure devices can be a very intriguing material platform if optoelectronic properties of the original semiconductor nanostructures can be tuned by explicitly controlling properties of the oxide coating. This paper describes our finding that optical properties of semiconductor nanowires can be tuned by depositing a thin layer of metal oxide. In this experiment, indium phosphide nanowires were grown by metal organic chemical vapor deposition on silicon substrates with gold catalyst. The nanowires formed three-dimensional nanowire networks from which collective optical properties were obtained. The nanowire network was 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. We observed continuous blue shift in photoluminescence spectra 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 an intrinsic negative fixed charge from the oxide surface. Samples were further characterized by scanning electron microscopy, transmission electron microscopy, and selective area diffractometry in an attempt to explain the physical mechanisms for the blue shift.

Fryauf, David M.; Zhang, Junce; Norris, Kate J.; Diaz Leon, Juan; Kobayashi, Nobuhiko P.

2013-09-01

102

Design, analysis, and fabrication of oxide-coated iridium/rhenium combustion chambers  

Science.gov (United States)

Iridium-coated rhenium (Ir/Re) combustion chambers provide high temperature, oxidation-resistant operation for radiation-cooled liquid-fueled rocket engines. A 22-N (5-lb(sub f)) chamber has been operated for 15 hours at 2200 C (4000 F) using nitrogen tetroxide/monomethyl hydrazine (NTO/MMH) propellant, with negligible internal erosion. The oxidation resistance of these chambers could be further increased by the addition of refractory oxide coatings, providing longer life and/or operation in more oxidizing and higher temperature environments. The oxide coatings would serve as a thermal and diffusion barrier for the iridium coating, lowering the temperature of the iridium layer while also preventing the ingress of oxygen and egress of iridium oxides. This would serve to slow the failure mechanisms of Ir/Re chambers, namely the diffusion of rhenium to the inner surface and the oxidation of iridium. Such protection could extend chamber lifetimes by tens or perhaps hundreds of hours, and allow chamber operation on stoichiometric or higher mixture ratio oxygen/hydrogen (O2/H2) propellant. Extensive thermomechanical, thermochemical, and mass transport modeling was performed as a key material/structure design tool. Based on the results of these analyses, several 22-N oxide-coated Ir/Re chambers were fabricated and delivered to NASA Lewis Research Center for hot-fire testing.

Jang, Q.; Tuffias, R. H.; Laferla, R.; Ghoniem, N. M.

1993-01-01

103

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

Directory of Open Access Journals (Sweden)

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

104

Analysis methods and size effects in the indentation fracture toughness assessment of very thin oxide coatings on glass  

Science.gov (United States)

Very thin oxide coatings (anti-reflection and barrier layers in low emissivity architectural glass have been studied by nanoindentation methods to determine the effect of coating thickness on fracture toughness. Traditional microindentation-derived methods to determine the fracture toughness are unsuitable for assessing very thin coatings (glass substrate. For oxide coatings in the thickness range 100 to 400 nm no size effects in fracture toughness were observed.

Bull, Steve J.

2011-07-01

105

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.

106

Chemical synthesis and characterization of manganese oxide coated Ni particles  

Science.gov (United States)

Nanosized Ni particles with an average diameter of about 8 nm were prepared by reducing of NiCl2 with sodium borohydride (NaBH4) in aqueous solution. By moderate annealing in protective atmosphere, the composite grew up to be 15-20 nm particles. Both of the as-prepared and annealed Ni particles were coated by a layer of manganese oxide via decomposition reaction in aqueous KMnO4 solution. Hysteresis loops of as-prepared samples show a large increase in the magnetization with decreasing temperature and an unsaturated component at high magnetic field. In contrast, the ferromagnetic characteristics of annealed one are much stronger with large magnetization and coercivity. The thermomagnetic curves verified the coexistence of ferromagnetic Ni and antiferromangetic Mn oxide phases. But there exists no exchange bias behavior in the samples, even though the interface structure between the ferromagnetic Ni core and the antiferromagnetic manganese oxides has been distinctly formed. The absence of exchange bias probably originates from the weak ferromagnetic characteristic of Ni cores.

An, Jing; Xu, LiHong; He, Jun; Zhao, DongLiang; Liu, ZhongYuan

2013-08-01

107

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

108

Removal of copper(II) and lead(II) from aqueous solution by manganese oxide coated sand  

International Nuclear Information System (INIS)

The preparation, characterization, and sorption properties for Cu(II) and Pb(II) of manganese oxide coated sand (MOCS) were investigated. A scanning electron microscope (SEM), X-ray diffraction spectrum (XRD) and BET analyses were used to observe the surface properties of the coated layer. An energy dispersive analysis of X-ray (EDAX) and X-ray photoelectron spectroscopy (XPS) were used for characterizing metal adsorption sites on the surface of MOCS. The quantity of manganese on MOCS was determined by means of acid digestion analysis. The adsorption experiments were carried out as a function of solution pH, adsorbent dose, ionic strength, contact time and temperature. Binding of Cu(II) and Pb(II) ions with MOCS was highly pH dependent with an increase in the extent of adsorption with the pH of the media investigated. After the Cu(II) and Pb(II) adsorption by MOCS, the pH in solution was decreased. Cu(II) and Pb(II) uptake were found to increase with the temperature. Further, the removal efficiency of Cu(II) and Pb(II) increased with increasing adsorbent dose and decreased with ionic strength. The pseudo-first-order kinetic model, pseudo-second-order kinetic model, intraparticle diffusion model and Elovich equation model were used to describe the kinetic data and the data constants were evaluated. The pseudo-second-order model was the best choice among all the kinetic models to describe the adsorption behavior of Cu(II) and Pb(II) onto MOCS, suggesting that the adsorp(II) onto MOCS, suggesting that the adsorption mechanism might be a chemisorption process. The activation energy of adsorption (E a) was determined as Cu(II) 4.98 kJ mol-1 and Pb(II) 2.10 kJ mol-1, respectively. The low value of E a shows that Cu(II) and Pb(II) adsorption process by MOCS may involve a non-activated chemical adsorption and a physical sorption

109

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

Science.gov (United States)

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.

Sladkevich, S.; Gun, J.; Prikhodchenko, P. V.; Gutkin, V.; Mikhaylov, A. A.; Novotortsev, V. M.; Zhu, J. X.; Yang, D.; Hng, H. H.; Tay, Y. Y.; Tsakadze, Z.; Lev, O.

2012-12-01

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  

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

112

Entropy and enthalpy of adsorption of gaseous metal chlorides and oxychlorides on quartz glass as functions of adsorbate composition  

Energy Technology Data Exchange (ETDEWEB)

Microamounts of radionuclides have been used for studying adsorption of chlorides of Cs, Au, Tb, Tm, Pb, Zr, Hf, Sb, Bi, and Nb, as well as of oxychlorides of some of these elements, in a quartz thermochromatographic column with SOCl{sub 2} as chlorinating component of the carrier gas. Based on the temperature dependence of the bulk-to-surface concentration ratio, enthalpy and enthropy changes in the course of adsorption (for a certain standard state) have been determined for a number of compounds. The {Delta}S{sub a}{sup o}values fall within a fairly narrow range and correlate with the number of atoms m in the sorbate molecule: {Delta}S{sub a}{sup o}[J mol{sup -1}K{sup -1}] = -(184{plus_minus}3) + (8.5{plus_minus}0.2)m. Thus, a simplified equation has been derived for estimating {Delta}H{sub a}{sup o}based on the adsorption constant measured for only one temperature: {Delta}H{sub a}{sup o}[kJ mol{sup -1}]= [(8.5 {plus_minus} 0.2)m - (184 {plus_minus}3) - R ln K{sub a}{sup o}]T. Reproducible {Delta}H{sub a}{sup o}values have been obtained only in the case when the inert component of the carrier gas was thoroughly predried and the column was pretreated with SOCl{sub 2}vapor for a long time, i.e., in the case of the high degree of Cl{sup -} modification of the quartz surface. The parameter {vert_bar}{Delta}H{sub a}{sup o}{vert_bar} usually approximates the enthalpy of vaporization of the adsorbate substance.

Chuburkov, Yu.T.; Seb, H.H.; Alpert, L.K. [Joint Inst. of Nuclear Research, Dubna (Russian Federation)] [and others

1995-11-01

113

Origin of complex impact craters on native oxide coated silicon surfaces  

International Nuclear Information System (INIS)

Crater structures induced by impact of keV-energy Arn+ cluster ions on silicon surfaces are measured with atomic force microscopy. Complex crater structures consisting of a central hillock and outer rim are observed more often on targets covered with a native silicon oxide layer than on targets without the oxide layer. To explain the formation of these complex crater structures, classical molecular dynamics simulations of Ar cluster impacts on oxide coated silicon surfaces, as well as on bulk amorphous silica, amorphous Si, and crystalline Si substrates, are carried out. The diameter of the simulated hillock structures in the silicon oxide layer is in agreement with the experimental results, but the simulations cannot directly explain the height of hillocks and the outer rim structures when the oxide coated silicon substrate is free of defects. However, in simulations of 5 keV/atom Ar12 cluster impacts, transient displacements of the amorphous silicon or silicon oxide substrate surfaces are induced in an approximately 50 nm wide area surrounding the impact point. In silicon oxide, the transient displacements induce small topographical changes on the surface in the vicinity of the central hillock. The comparison of cluster stopping mechanisms in the various silicon oxide and silicon structures shows that the largest lateral momentum is induced in the silicon oxide layer during the impact; thus, the transient displacements on the surfacethe transient displacements on the surface are stronger than in the other substrates. This can be a reason for the higher frequency of occurrence of the complex craters on oxide coated silicon

114

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

Directory of Open Access Journals (Sweden)

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

115

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

Directory of Open Access Journals (Sweden)

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

116

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

117

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 microscopy. The electrochemical properties of activated titanium anodes were investigated by cyclic voltammetry and polarization measurements in a H2SO4- and NaCl-containing electrolyte, as well as in seawater sampled on the Adriatic coast in Tivat, Montenegro. The anode stability during operation in seawater was investigated by the galvanostatic accelerated corrosion stability test. The morphology and electrochemical characteristics of the ternary coating are compared to that of a sol-gel-prepared binary Ti0.6Ru0.4O2 coating. The activity of the ternary coating was similar to that of the binary Ti0.6Ru0.4O2 coating in the investigated solutions. However, the corrosion stability in seawater is found to be considerably greater for the ternary coating.

VLADIMIR V. PANIC

2007-12-01

118

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

119

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

120

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.

121

Long-term corrosion inhibition mechanism of microarc oxidation coated AZ31 Mg alloys for biomedical applications  

International Nuclear Information System (INIS)

Highlights: ? The corrosion behavior is significantly affected by the long-term immersion. ? The degradation is inhibited due to the corrosion product layer. ? The corrosion resistance is enhanced by optimized MAO electrolyte concentrations. ? The corrosion inhibition mechanism is presented by a Flash animation. - Abstract: This paper addresses the long-term corrosion behavior of microarc oxidation coated Mg alloys immersed in simulated body fluid for 28 days. The coatings on AZ31 Mg alloys were produced in the electrolyte of sodium phosphate (Na3PO4) at the concentration of 20 g/L, 30 g/L and 40 g/L, respectively. Scanning electron microscope (SEM) and optical micrograph were used to observe the microstructure of the samples before and after corrosion. The composition of the MAO coating and corrosion products were determined by X-Ray Diffraction (XRD). Corrosion product identification showed that hydroxyapatite (HA) was formed on the surface of the corroded samples. The ratio of Ca/P in HA determined by the X-ray Fluorescence (XRF) technique showed that HA is an acceptable biocompatible implant material. The potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were employed to characterize the corrosion rate and the electrochemical impedance. The corrosion resistance of the coated Mg alloys can be enhanced by optimizing the electrolyte concentrations for fabricating samples, and is enhanced after immersing the coated samples in simulated body fluid for more than 14 days. The enhanced corrosion resistance after long-term immersion is attributed to a corrosion product layer formed on the sample surface. The inhibition mechanism of the corrosion process is discussed and presented with an animation

122

Influence of ionic strength and pH on the limitation of latex microsphere deposition sites on iron-oxide coated sand by humic acid  

International Nuclear Information System (INIS)

This study, for the first time, investigates and quantifies the influence of slight changes in solution pH and ionic strength (IS) on colloidal microsphere deposition site coverage by Suwannee River Humic Acid (SRHA) in a column matrix packed with saturated iron-oxide coated sand. Triple pulse experimental (TPE) results show adsorbed SRHA enhances microsphere mobility more at higher pH and lower IS and covers more sites than at higher IS and lower pH. Random sequential adsorption (RSA) modelling of experimental data suggests 1 ?g of adsorbed SRHA occupied 9.28 ± 0.03 x 109 sites at pH7.6 and IS of 1.6 mMol but covered 2.75 ± 0.2 x 109 sites at pH6.3 and IS of 20 mMol. Experimental responses are suspected to arise from molecular conformation changes whereby SRHA extends more at higher pH and lower ionic strength but is more compact at lower pH and higher IS. Results suggest effects of pH and IS on regulating SRHA conformation were additive. - Highlights: ? We quantified the coupled role of pH and IS and humic acid on colloid deposition. ? Humic acid enhances microsphere mobility more at higher pH and lower IS. ? pH and IS may control the behaviour of humic acid by regulating its conformation. ? The effect of pH and IS on regulating humic acid conformation is additive. - This paper quantifies the impact of pH and ionic strength on the transient deposition behaviour of colloids in porous medium in the presence of humic acid.ce of humic acid.

123

Influence of ionic strength and pH on the limitation of latex microsphere deposition sites on iron-oxide coated sand by humic acid  

Energy Technology Data Exchange (ETDEWEB)

This study, for the first time, investigates and quantifies the influence of slight changes in solution pH and ionic strength (IS) on colloidal microsphere deposition site coverage by Suwannee River Humic Acid (SRHA) in a column matrix packed with saturated iron-oxide coated sand. Triple pulse experimental (TPE) results show adsorbed SRHA enhances microsphere mobility more at higher pH and lower IS and covers more sites than at higher IS and lower pH. Random sequential adsorption (RSA) modelling of experimental data suggests 1 {mu}g of adsorbed SRHA occupied 9.28 {+-} 0.03 x 10{sup 9} sites at pH7.6 and IS of 1.6 mMol but covered 2.75 {+-} 0.2 x 10{sup 9} sites at pH6.3 and IS of 20 mMol. Experimental responses are suspected to arise from molecular conformation changes whereby SRHA extends more at higher pH and lower ionic strength but is more compact at lower pH and higher IS. Results suggest effects of pH and IS on regulating SRHA conformation were additive. - Highlights: > We quantified the coupled role of pH and IS and humic acid on colloid deposition. > Humic acid enhances microsphere mobility more at higher pH and lower IS. > pH and IS may control the behaviour of humic acid by regulating its conformation. > The effect of pH and IS on regulating humic acid conformation is additive. - This paper quantifies the impact of pH and ionic strength on the transient deposition behaviour of colloids in porous medium in the presence of humic acid.

Yang, X. [School of Planning, Architecture and Civil Engineering, Queen' s University Belfast, David Keir Building, Stranmillis Road, Belfast BT9 5AG, N. Ireland (United Kingdom); Flynn, R., E-mail: r.flynn@qub.ac.uk [School of Planning, Architecture and Civil Engineering, Queen' s University Belfast, David Keir Building, Stranmillis Road, Belfast BT9 5AG, N. Ireland (United Kingdom); Kammer, F. von der, E-mail: frank.von.der.kammer@univie.ac.at [Department of Environmental Geosciences, University of Vienna, Althanstrasse 14, 1090 Vienna (Austria); Hofmann, T. [Department of Environmental Geosciences, University of Vienna, Althanstrasse 14, 1090 Vienna (Austria)

2011-07-15

124

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

Energy Technology Data Exchange (ETDEWEB)

Highlights: Black-Right-Pointing-Pointer PEO (plasma electrolytic oxidation) for production of oxide coatings on a Ti-6Al-4V alloy. Black-Right-Pointing-Pointer Two different current modes namely pulsed unipolar and bipolar was used. Black-Right-Pointing-Pointer Optical emission spectroscopy (OES) was used to characterize the PEO plasma. Black-Right-Pointing-Pointer This is the first attempt to characterize spectroscopically the PEO plasma of Ti and its alloys. Black-Right-Pointing-Pointer 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 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.

Hussein, R.O., E-mail: husseinr@uwindsor.ca [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); Northwood, D.O., E-mail: dnorthwo@uwindsor.ca [Department of Mechanical, Automotive and Materials Engineering, University of Windsor, Windsor, ON, N9B 3P4 (Canada)

2012-05-15

125

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.

126

Properties and structure of oxidized coatings deposited onto Al-Cu and Al-Mg alloys  

Science.gov (United States)

The results of new studies of creating protective oxide coatings based on Al2O3 (Si, Mn) and deposited onto aluminum alloys using electrolyte-plasma oxidation are presented. An analysis is performed by scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), X-ray diffraction, Rutherford backscattering of 4He+ and protons, nanoindentation, scratching, friction coefficient measurements, and acoustic emission measurements. The results demonstrate that the deposited coatings have a high quality, hardness, and wear resistance and a low thermal diffusivity. Apart from Al2O3, the coatings are found to have Si, Mn, C, and Ca. The stoichiometry of the coatings is determined. The density and hardness of the coatings are close to those of ?-Al2O3 in the coating on an Al-Cu (D-16) substrate, and these values of the coating on an Al-Mg (S006) are lower by a factor of 1.5.

Pogrebnyak, A. D.; Kylyshkanov, M. K.; Tyurin, Yu. N.; Kaverina, A. Sh.; Yakushchenko, I. V.; Borisenko, A. A.; Postol'ny, B. A.; Kulik, I. A.

2012-06-01

127

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.

128

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

Energy Technology Data Exchange (ETDEWEB)

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 Wenbin [Key Laboratory for Radiation Beam Technology and Materials Modification, Institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing, 100875 (China); Wang Chao [Key Laboratory for Radiation Beam Technology and Materials Modification, Institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing, 100875 (China); Deng Zhiwei [Key Laboratory for Radiation Beam Technology and Materials Modification, Institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing, 100875 (China); Chen Ruyi [Key Laboratory for Radiation Beam Technology and Materials Modification, Institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing, 100875 (China); Li Yongliang [Analytical and Testing Centre, Beijing Normal University, Beijing, 100875 (China); Zhang Tonghe [Key Laboratory for Radiation Beam Technology and Materials Modification, Institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing, 100875 (China)

2002-11-11

129

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

International Nuclear Information System (INIS)

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 ?-Al2O3 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

130

Magnetoelectric behavior of carbonyl iron mixed Mn oxide-coated ferrite nanoparticles  

Science.gov (United States)

The dielectric and magnetic properties of manganese oxide-coated Fe3O4 nanoparticles (NPs) were measured by the cavity perturbation method at x-band microwave frequencies ranging from 7-12.5 GHz with controlled external magnetic field up to 2.2 kOe at room temperature. Different ratios (5%, 10%, and 20% by weight) of coated NPs were prepared by sol-gel method then mixed with carbonyl iron powder in epoxy matrix. The saturation magnetization is inversely proportional to the NPs ratio in the mixture between 150 and 180 emu/g. The real part of the permittivity decreased with increasing NPs concentration, but the permittivity change by magnetic field increased. The tunability behavior is explained by insulator-ferromagnetic interface magnetoelectricity and the large surface volume ratio for the NPs.

Ahad, Faris B. Abdul; Lee, Shang-Fan; Hung, Dung-Shing; Yao, Yeong-Der; Yang, Ruey-Bin; Lin, Chung-Kwei; Tsay, Chien-Yie

2010-05-01

131

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

International Nuclear Information System (INIS)

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 Ta2O5 and Ta2O5-Ag coatings with 12.5 at. % of Ag exhibit improved antibacterial effects against S. aureus and have good skin fibroblast cell cellular biocompatibility

132

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...

133

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

134

Structure and magnetic properties of boron-oxide-coated Fe(B) nanocapsules prepared by arc discharge in diborane  

Science.gov (United States)

The structure and magnetic properties of boron-oxide-encapsulated magnetic nanocapsules fabricated by arc discharge in diborane (B2H6) atmosphere have been investigated. The structure of boron-oxide-coated Fe(B) nanocapsules is different from that of carbon-coated nanocapsules. In contrast to carbon-coated nanocapsules consisting of a crystalline shell of graphite and a core of ?-Fe and/or Fe3C, boron-oxide-coated Fe nanocapsules show an amorphous surface layer and a core of ?-Fe [and ?-Fe(B) solid solution], ?-Fe, FeB, and/or Fe3B phases. The loop shift in the hysteresis loop indicates the existence of the exchange bias between ferromagnetic and antiferromagnetic components at room temperature. The Fe3O4 phase contributes to the exchange bias as antiferromagnetic components. A very wide energy barrier distribution exists in the Fe(B) nanocapsules.

Zhang, Z. D.; Yu, J. L.; Zheng, J. G.; Skorvanek, I.; Kovac, J.; Dong, X. L.; Li, Z. J.; Jin, S. R.; Yang, H. C.; Guo, Z. J.; Liu, W.; Zhao, X. G.

2001-07-01

135

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

136

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

137

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

138

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

139

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

140

Corrosion properties of steel protected by nanometre-thick oxide coatings  

International Nuclear Information System (INIS)

Highlights: • 40–50 nm mixed alumina–tantala coatings were grown by atomic layer deposition. • Effects of substrate surface finish and oxide mix were analysed. • Nanolaminate stacks are better resistant to breakdown. • Localised corrosion occurs at pre-existing coating defects exposing substrate sites. • Substrate brushing and H2–Ar plasma pre-treatment hinder pit initiation. - Abstract: A comprehensive study of the corrosion properties of low alloy steel protected by 40–50 nm aluminium and tantalum mixed oxide coatings grown by atomic layer deposition is reported. Electrochemical and surface analysis was performed to address the effect of substrate surface finish and whether an oxide mixture or nanolaminate was used. There was no dissolution or breakdown for nanolaminate alumina/tantala stacks in acidic NaCl solution. Localised corrosion (pitting) took place when defects exposing the substrate pre-existed in the coating. Substrate pre-treatment by brushing and H2–Ar plasma was instrumental to block or slow down pit initiation by reducing the defect dimensions

141

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

142

Reduced bleaching in organic nanofibers by bilayer polymer/oxide coating  

International Nuclear Information System (INIS)

Para-hexaphenylene (p-6P) molecules exhibit a characteristic photoinduced reaction (bleaching) resulting in a decrease in luminescence intensity upon UV light exposure, 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 and Al2O3) were applied onto p-6P nanofibers. These treatments caused a reduction in the bleaching reaction but in addition, the nanofiber luminescence spectrum was significantly altered. It was observed that some polymer coatings [a statistical copolymer of tetrafluoroethylene and 2,2-bis-trifluoromethyl-4,5-difluoro-1,3-dioxole, P(TFE-PDD), and poly(methyl methacrylate), PMMA] do not interfere with the luminescence spectrum from the p-6P 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 p-6P 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 in bleaching without affecting significantly the emission spectrum from the nanofibers.

143

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

144

Synthesis of iron oxide coated fluoridated HAp/Ln³? (Ln = Eu or Tb) nanocomposites for biological applications.  

Science.gov (United States)

Fluorescent-magnetic iron oxide coated fluoridated HAp/Ln(3+) (Ln = Eu or Tb) nanocomposites were prepared. After transforming hydrophobic fluoridated HAp/Ln(3+) nanorods into hydrophilic ones, iron oxide particles were coated on their surface via thermal decomposition of Fe(acac)3. Fluorescent-magnetic nanocomposites developed in this study demonstrate excellent fluorescent-magnetic properties and prominent biocompatibility. PMID:25267372

Pan, Jie; Zhang, Juchen; Wang, Lili; Wan, Dong

2014-11-21

145

Removal of dissolved heavy metals from pre-settled stormwater runoff by iron-oxide coated sand (IOCS)  

OpenAIRE

Sorption to iron-oxide coated sand (IOCS) is a promosing technology for removal of the dissolved heavy metal fraction in stormwater runoff. The development of a new technology is necessary since studies of stormwater runoff from traffic areas indicate that an oil separator and detention pond may not guarantee that emission limit values set by the Danish EPA are satisfied. Runoff water was sampled from an urban highway, allowed to settle for 24 hours to simulate the effect of a detention pond,...

Møller, J.; Ledin, Anna; Mikkelsen, Peter Steen

2006-01-01

146

Urban runoff treatment using nano-sized iron oxide coated sand with and without magnetic field applying  

OpenAIRE

Increase of impervious surfaces in urban area followed with increases in runoff volume and peak flow, leads to increase in urban storm water pollution. The polluted runoff has many adverse impacts on human life and environment. For that reason, the aim of this study was to investigate the efficiency of nano iron oxide coated sand with and without magnetic field in treatment of urban runoff. In present work, synthetic urban runoff was treated in continuous separate columns system which was fil...

Khiadani, Mehdi; Zarrabi, Mansur; Foroughi, Maryam

2013-01-01

147

PVP-functionalized nanometre scale metal oxide coatings for cathode materials: successful application to LiMn2O4 spinel nanoparticles.  

Science.gov (United States)

PVP functionalized metal oxide coatings on spinel nanoparticles demonstrated significantly improved rate characteristics under extensive cycling at 65 degrees C and exhibited over 100% improved capacity retention compared to the bare counterpart. PMID:18802594

Lim, Sunhye; Cho, Jaephil

2008-10-01

148

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

149

Formation of Manganese Oxide Coatings onto Sand for Adsorption of Trace Metals from Groundwater.  

Science.gov (United States)

Manganese oxide (MnO) occurs naturally in soil and has a high affinity for trace metals adsorption. In this work, we quantified the factors (pH; flow rate; use of oxidants such as bleach, HO, and O; initial Mn(II) concentrations; and two types of geologic media) affecting MnO coatings onto Ottawa and aquifer sand using batch and column experiments. The batch experiments consisted of manual and automated titration, and the column experiments mimicked natural MnO adsorption and oxidation cycles as a strategy for in situ adsorption. A Pb solution of 50 mg L was passed through MnO-coated sand at a flow rate of 4 mL min to determine its adsorption capacity. Batch experimental results showed that MnO coatings increased from pH 6 to 8, with maximum MnO coating occurring at pH 8. Regarding MnO coatings, bleach and O were highly effective compared with HO. The Ottawa sand had approximately twice the MnO coating of aquifer sand. The sequential increase in initial Mn(II) concentrations on both sands resulted in incremental buildup of MnO. The automated procedure enhanced MnO coatings by 3.5 times compared with manual batch experiments. Column results showed that MnO coatings were highly dependent on initial Mn(II) and oxidant concentrations, pH, flow rate, number of cycles (h), and the type of geologic media used. Manganese oxide coating exceeded 1700 mg kg for Ottawa sand and 130 mg kg for aquifer sand. The Pb adsorption exceeded 2200 mg kg for the Ottawa sand and 300 mg kg for the aquifer sand. PMID:25602414

Tilak, A S; Ojewole, S; Williford, C W; Fox, G A; Sobecki, T M; Larson, S L

2013-11-01

150

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

151

Nanostructured hydrophobic DC sputtered inorganic oxide coating for outdoor glass insulators  

Energy Technology Data Exchange (ETDEWEB)

Graphical abstract: - Highlights: • Deposition of contamination on outdoor glass insulators and its physical and economical consequences were discussed. • Synthesis of nanostructured hydrophobic HfO{sub 2} film on glass as a remedial measure by varying DC sputtering power. • Investigated and correlated structural, optical, electrical and hydrophobic properties of HfO{sub 2} films with respect to power. • Optimum results were obtained at a 50 W DC sputtering power. - Abstract: 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 (?10{sup 4} ? cm) to hinder the flow of leakage current through the film. The dielectric constant (?) was found to be thickness dependent and also high enough (?{sub max} = 23.12) to bear the large electric field of outdoor insulators.

Dave, V. [Department of Electrical Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Institute Instrumentation Centre, Indian Institute of Technology, Roorkee, Roorkee 247667 (India); Gupta, H.O. [Department of Electrical Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Chandra, R., E-mail: ramesfic@gmail.com [Institute Instrumentation Centre, Indian Institute of Technology, Roorkee, Roorkee 247667 (India)

2014-03-01

152

Nanostructured hydrophobic DC sputtered inorganic oxide coating for outdoor glass insulators  

International Nuclear Information System (INIS)

Graphical abstract: - Highlights: • Deposition of contamination on outdoor glass insulators and its physical and economical consequences were discussed. • Synthesis of nanostructured hydrophobic HfO2 film on glass as a remedial measure by varying DC sputtering power. • Investigated and correlated structural, optical, electrical and hydrophobic properties of HfO2 films with respect to power. • Optimum results were obtained at a 50 W DC sputtering power. - Abstract: 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

153

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

154

Urban runoff treatment using nano-sized iron oxide coated sand with and without magnetic field applying.  

Science.gov (United States)

Increase of impervious surfaces in urban area followed with increases in runoff volume and peak flow, leads to increase in urban storm water pollution. The polluted runoff has many adverse impacts on human life and environment. For that reason, the aim of this study was to investigate the efficiency of nano iron oxide coated sand with and without magnetic field in treatment of urban runoff. In present work, synthetic urban runoff was treated in continuous separate columns system which was filled with nano iron oxide coated sand with and without magnetic field. Several experimental parameters such as heavy metals, turbidity, pH, nitrate and phosphate were controlled for investigate of system efficiency. The prepared column materials were characterized with Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray analysis (EDXA) instruments. SEM and EDXA analyses proved that the sand has been coated with nano iron oxide (Fe3O4) successfully. The results of SEM and EDXA instruments well demonstrate the formation of nano iron oxide (Fe3O4) on sand particle. Removal efficiency without magnetic field for turbidity; Pb, Zn, Cd and PO4 were observed to be 90.8%, 73.3%, 75.8%, 85.6% and 67.5%, respectively. When magnetic field was applied, the removal efficiency for turbidity, Pb, Zn, Cd and PO4 was increased to 95.7%, 89.5%, 79.9%, 91.5% and 75.6% respectively. In addition, it was observed that coated sand and magnetic field was not able to remove NO3 ions. Statistical analyses of data indicated that there was a significant difference between removals of pollutants in two tested columns. Results of this study well demonstrate the efficiency of nanosized iron oxide-coated sand in treatment of urban runoff quality; upon 75% of pollutants could be removed. In addition, in the case of magnetic field system efficiency can be improved significantly. PMID:24360061

Khiadani Hajian, Mehdi; Zarrabi, Mansur; Foroughi, Maryam

2013-01-01

155

Removal of arsenic from contaminated water sources by sorption onto iron-oxide-coated polymeric materials  

OpenAIRE

The modification of polymeric materials (polystyrene and polyHIPE) by coating their surface with appropriate adsorbing agents (i.e. iron hydroxides) was investigated in the present work, in order to apply the modified media in the removal of inorganic arsenic anions from contaminated water sources. The method, termed adsorptive filtration, has been classified as an emerging technology in water treatment processes as it presents several advantages towards conventional technologies: the product...

Katsoyiannis, I. A.; ?????????????, ?. ?.; Zouboulis, A. I.; ???????????, ?. ?.

2009-01-01

156

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

Directory of Open Access Journals (Sweden)

Full Text Available Dye-sensitized titanium oxide electrodes were prepared by immobilizing a novel ruthenium complex, di(isothiocy- anatobis(4-methyl-4’-vinyl-2,2’-bipyridineruthenium(II [(NCS2(mvbpy2Ru(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 method, in which the electrolysis step and the film deposition step were individually performed. The incident photon-to-current conversion efficiency (IPCE of the Ru complex film on a TiO2/FTO electrode was disappointedly insufficient (1.2% at 440 nm. In sharp contrast, the Ru(II complex/so- dium 4-vinylbenzenesulfonate composite film deposited on the surface of a TiO2/FTO electrode showed maximum IPCE of 31.7% at 438 nm.

Yi Liu

2013-05-01

157

Fabrication and evaluation of low-cost agarose-zinc nanoporous composite matrix: influence of adsorbent density and size distribution on the performance of expanded beds.  

Science.gov (United States)

Expanded bed adsorption (EBA), a promising and practical separation technique for adsorption of nanobioproduct/bioproduct, has been widely studied in the past two decades. The development of adsorbent with the special design for expanded bed process is a challenging course. To reduce the costs of adsorbent preparation, fine zinc powder was used as the inexpensive densifier. A series of matrices named Ag-Zn were prepared by water-in-oil emulsification method. The structure and morphology of the prepared matrix were studied by the optical microscope (OM) and scanning electron microscopy (SEM). The physical properties as a function of zinc powder ratio to agarose slurry were measured. The prepared matrices had regular spherical shape, and followed logarithmic normal size distribution with the range of 75-330 ?m, mean diameter of 140.54-191.11 ?m, wet density of 1.33-2.01 g/ml, water content of 0.45-0.75, porosity of 0.86-0.97 and pore size of about 40-90 nm. The bed expansion factor at the range of 2-3 was examined. The obtained results indicated that the expansion factor was decreased with increasing of matrix density. In addition, it was found that matrices with large particle size were suitable for high operation flow rate. The hydrodynamic properties were determined in expanded bed by the residence time distribution method (RTD). The effects of flow velocity, expansion factor and density of matrix on the hydrodynamic properties were also investigated. Moreover, the influence of particle size distribution on the performance of expanded bed has been studied. Therefore, three different particle size fractions (65-140, 215-280 and 65-280 ?m) were assessed. The results indicated that dispersion in liquid-solid expanded beds increased with increasing flow rate and expansion factor; and matrix with a wide particle size distribution leaded to a reduced axial dispersion compared to matrices with a narrow size distribution. The axial dispersion coefficient also enhanced with the increasing of matrix density. It was found that flow rate was the most essential factor to effect on the hydrodynamic characteristics in the bed. For all the prepared matrices, the values of axial mixing coefficients (D(axl)) were smaller than 1.0 × 10?? m²/s when flow velocities in expanded bed were less than 700 cm/h. All the results indicate that the prepared matrix show good expansion and stability in expanded bed; and it is suitable for expanded bed processes as an economical adsorbent. PMID:22920304

Asghari, Fateme; Jahanshahi, Mohsen

2012-09-28

158

Molecular Adsorber Coating  

Science.gov (United States)

A document discusses a zeolite-based sprayable molecular adsorber coating that has been developed to alleviate the size and weight issues of current ceramic puck-based technology, while providing a configuration that more projects can use to protect against degradation from outgassed materials within a spacecraft, particularly contamination-sensitive instruments. This coating system demonstrates five times the adsorption capacity of previously developed adsorber coating slurries. The molecular adsorber formulation was developed and 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. 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-based coatings. The coating can also function as a thermal- control coating. This adsorber will dramatically reduce the mass and volume restrictions, and is less expensive than the currently used molecular adsorber puck design.

Straka, Sharon; Peters, Wanda; Hasegawa, Mark; Hedgeland, Randy; Petro, John; Novo-Gradac, Kevin; Wong, Alfred; Triolo, Jack; Miller, Cory

2011-01-01

159

Magnetic composite of Fe3O4 and activated carbon as a adsorbent for separation of trace Sr(II) from radioactive wastewater  

International Nuclear Information System (INIS)

Magnetic adsorbent of Fe3O4 and activated carbon (Fe3O4/AC) was prepared by chemical coprecipitation technique, and was characterized by SEM, TEM, BET, XRD, and VSM techniques in details. The adsorption results of Sr(II) on Fe3O4/AC revealed that Sr(II) adsorption on Fe3O4/AC surface was an spontaneous and endothermic process, and can be well described by the pseudo-second-order model. The adsorption of Sr(II) on Fe3O4/AC increased with increasing pH, and decreased with increasing ionic strength. Fe3O4/AC can be easily separated from aqueous solution with an external magnetic field after application. (author)

160

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.

161

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)

162

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

163

Plasma electrolytic oxide coatings on valve metals and their activity in CO oxidation  

Science.gov (United States)

Two approaches have been examined for obtaining titanium- or aluminum-supported catalysts with transition and noble metals using the plasma electrolytic oxidation (PEO) technique. Elemental compositions, distribution of active elements and catalytic activity in CO oxidation have been compared for composites formed by one-stage PEO technique and those obtained as a result of modification of PEO coatings by impregnation.

Lukiyanchuk, I. V.; Rudnev, V. S.; Tyrina, L. M.; Chernykh, I. V.

2014-10-01

164

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

165

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

166

Fretting wear behaviour of microarc oxidation coatings formed on titanium alloy against steel in unlubrication and oil lubrication  

Science.gov (United States)

Ceramic coatings were formed on Ti6Al4V alloy surface by microarc oxidation (MAO) in a Na 2SiO 3 system solution. Unlubricated, smear oil and oil bath lubricated fretting tests were performed on MAO coatings against 52100 steel on a fretting wear tester. Microstructural investigation of the worn surfaces was performed and the wear mechanisms were studied. The results show that the coatings are mainly composed of rutile and a small amount of anatase TiO 2, both in nano grain structure. Friction coefficient of microarc oxidation coatings under oil bath lubrication was significantly reduced, favorable stable at 0.15, which indicates that the coatings with oil lubricated lowered the shear and adhesive stresses between contact surfaces, consequently alleviating the possibility of initiation and propagation of cracks in the inner layer of the coating or titanium alloy substrate.

Wang, Yaming; Lei, Tingquan; Guo, Lixin; Jiang, Bailing

2006-09-01

167

Influence of albumin and inorganic ions on electrochemical corrosion behavior of plasma electrolytic oxidation coated magnesium for surgical implants  

Science.gov (United States)

Magnesium and its alloys are of great interest for biodegradable metallic devices. However, the degradation behavior and mechanisms of magnesium treated with coating in physiological environment in the presence of organic compound such as albumin have not been elucidated. In this study, the plasma electrolytic oxidation coated magnesium immersed in four different simulated body fluids: NaCl, PBS and with the addition of albumin to investigate the influence of protein and inorganic ions on degradation behavior by electrochemical methods. The results of electrochemical tests showed that aggressive corrosion took place in 0.9 wt.% NaCl solution; whereas albumin can act as an inhibitor, its adsorption impeded further dissolution of the coating. The mechanism was attributed to the synergistic effect of protein adsorption and precipitation of insoluble salts.

Wan, Peng; Lin, Xiao; Tan, LiLi; Li, Lugee; Li, WeiRong; Yang, Ke

2013-10-01

168

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

169

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)

170

Thermal behavior of Ni- and Cu-containing plasma electrolytic oxide coatings on titanium  

Science.gov (United States)

In this work the effect of thermal annealing on the surface composition, structure and catalytic activity in CO oxidation of NiO + CuO/TiO2/Ti composites is studied. The composites have been obtained by a plasma electrolytic oxidation (PEO) technique, followed by impregnation in a solution of nickel (II) and copper (II) salts and air annealing. The structures contain ˜20 at% Ni and ˜12 at% Cu. It has been shown that the additional air annealing of such structures at temperature above 750 °C results in phosphate crystallization in the coatings and decreasing of Cu concentration in the surface layers. A growth of filiform nanocrystals containing mainly oxygen compounds of nickel and titanium on the coating surface takes place at the temperatures above 700 °C. The nanocrystals have a diameter of 50-200 nm and lengths below 10 ?m. Such changes result in decreasing of catalytic activity of the composites in CO oxidation. At the same time the ascertained regularities may be of interest for obtaining the Ni-containing oxide catalysts with an extended surface, perspective for usage in organic catalysis or for preparing oxide nanofibers.

Rudnev, V. S.; Wybornov, S.; Lukiyanchuk, I. V.; Staedler, T.; Jiang, X.; Ustinov, A. Yu.; Vasilyeva, M. S.

2012-09-01

171

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.

172

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

173

Catalytic activity of mixed-oxide coatings based on perovskite lanthanum strontium cobaltate  

International Nuclear Information System (INIS)

Certain aspects concerning catalytic activity in reactions of CO oxidation and NO reduction of lanthanum-strontium cobaltate base coatings of perovskite structure, produced by polymer salt solutions pyrolysis, have been studied. It is shown that interaction with titanium substrate-carriers increases catalytic activity of the coatings. Comparative data on catalytic activity of different-composition cobaltate, titanium substrates and coatings on indifferent substrates have been obtained. Specific rate of catalytic reactions under pilot-industrial conditions have been calculated

174

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

175

Arsenic remediation of drinking water using iron-oxide coated coal bottom ash  

Energy Technology Data Exchange (ETDEWEB)

We describe laboratory and field results of a novel arsenic removal adsorbent called 'Arsenic Removal Using Bottom Ash' (ARUBA). ARUBA is prepared by coating particles of coal bottom ash, a waste material from coal fired power plants, with iron (hydr)oxide. The coating process is simple and conducted at room temperature and atmospheric pressure. Material costs for ARUBA are estimated to be low (~;;$0.08 per kg) and arsenic remediation with ARUBA has the potential to be affordable to resource-constrained communities. ARUBA is used for removing arsenic via a dispersal-and-removal process, and we envision that ARUBA would be used in community-scale water treatment centers. We show that ARUBA is able to reduce arsenic concentrations in contaminated Bangladesh groundwater to below the Bangladesh standard of 50 ppb. Using the Langmuir isotherm (R2 = 0.77) ARUBA's adsorption capacity in treating real groundwater is 2.6x10-6 mol/g (0.20 mg/g). Time-to-90percent (defined as the time interval for ARUBA to remove 90percent of the total amount of arsenic that is removed at equilibrium) is less than one hour. Reaction rates (pseudo-second-order kinetic model, R2>_ 0.99) increase from 2.4x105 to 7.2x105 g mol-1 min-1 as the groundwater arsenic concentration decreases from 560 to 170 ppb. We show that ARUBA's arsenic adsorption density (AAD), defined as the milligrams of arsenic removed at equilibrium per gram of ARUBA added, is linearly dependent on the initial arsenic concentration of the groundwater sample, for initial arsenic concentrations of up to 1600 ppb and an ARUBA dose of 4.0 g/L. This makes it easy to determine the amount of ARUBA required to treat a groundwater source when its arsenic concentration is known and less than 1600 ppb. Storing contaminated groundwater for two to three days before treatment is seen to significantly increase ARUBA's AAD. ARUBA can be separated from treated water by coagulation and clarification, which is expected to be less expensive than filtration of micron-scale particles, further contributing to the affordability of a community-scale water treatment center.

MATHIEU, JOHANNA L.; GADGIL, ASHOK J.; ADDY, SUSAN E.A.; KOWOLIK, KRISTIN

2010-06-01

176

Selective radium adsorbent  

International Nuclear Information System (INIS)

The selective radium adsorbent is a ternary compound insoluble in water consisting of cations forming water-soluble complexes with polyalkylene glycols and the derivatives thereof, e.g., the cations of barium, calcium, strontium, magnesium, zinc, and potassium; of polyalkylene glycol or its derivative soluble in water with 2 to 4 carbon atoms in the basic unit of molecular weight at least 20O; and of a reagent forming large anions, chosen from a group comprising heteropolyacids of the tungstophosphoric, molybdophosphoric and tungstosilicic acids type, sodium tetraphenylborate and bismuth iodides. This reagent is also water-soluble. (B.S.)

177

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

International Nuclear Information System (INIS)

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

178

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

Energy Technology Data Exchange (ETDEWEB)

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.

Sindhu, S. [Dept. of Instrumentation, Indian Institute of Science, Bangalore 560012 (India)]. E-mail: sindhu@isu.iisc.ernet.in; Narasimha Rao, K. [Dept. of Instrumentation, Indian Institute of Science, Bangalore 560012 (India); Ahuja, Sharath [Dept. of Instrumentation, Indian Institute of Science, Bangalore 560012 (India); Kumar, Anil [Dept. of Chemistry, Indian Institute of Technology, Bombay 400 076 (India); Gopal, E.S.R. [Dept. of Physics, Indian Institute of Science, Bangalore 560012 (India)

2006-07-25

179

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.

180

Iron oxide coating films in soda-lime glass by triboadhesion  

International Nuclear Information System (INIS)

In the triboadhesion process the coating material is passed through a rotating cotton mop and the substrate to be coated. The cotton mop rotates at high velocity and exerts pressure on the surface of the substrate. The combined effect of pressure and velocity of the coating mop on the substrate increases its temperature close to the melting point, allowing deposition and diffusion of the coating material within the substrate. After it is deposited, its particles are embedded within the base material forming a thin film composite. The amount of the coating material deposited on the substrate has its maximum at the surface and then decreases as a function of the local temperature within the base material. Bearing this in mind, in the present work, triboadhesion is employed to deposit iron oxide in a substrate of soda-lime glass, with the purpose of determining the feasibility of using this technique for solar control coatings. It was found, through electronic scan microscopy, that a composite material film is formed following the coating direction. Reflectance and transmittance tests were carried out on the glass samples. A 20% difference was found in the visible spectral region (VIS), and a reduction between 10 and 20% in the Near Infrared Region (NIR). These results showed that the triboadhesion is a promising technique for the application of thin films for solar control or solar cells

181

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.)

182

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

183

Green Adsorbents for Wastewaters: A Critical Review  

Directory of Open Access Journals (Sweden)

Full Text Available One of the most serious environmental problems is the existence of hazardous and toxic pollutants in industrial wastewaters. The major hindrance is the simultaneous existence of many/different types of pollutants as (i dyes; (ii heavy metals; (iii phenols; (iv pesticides and (v pharmaceuticals. Adsorption is considered to be one of the most promising techniques for wastewater treatment over the last decades. The economic crisis of the 2000s led researchers to turn their interest in adsorbent materials with lower cost. In this review article, a new term will be introduced, which is called “green adsorption”. Under this term, it is meant the low-cost materials originated from: (i agricultural sources and by-products (fruits, vegetables, foods; (ii agricultural residues and wastes; (iii low-cost sources from which most complex adsorbents will be produced (i.e., activated carbons after pyrolysis of agricultural sources. These “green adsorbents” are expected to be inferior (regarding their adsorption capacity to the super-adsorbents of previous literature (complex materials as modified chitosans, activated carbons, structurally-complex inorganic composite materials etc., but their cost-potential makes them competitive. This review is a critical approach to green adsorption, discussing many different (maybe in some occasions doubtful topics such as: (i adsorption capacity; (ii kinetic modeling (given the ultimate target to scale up the batch experimental data to fixed-bed column calculations for designing/optimizing commercial processes and (iii critical techno-economical data of green adsorption processes in order to scale-up experiments (from lab to industry with economic analysis and perspectives of the use of green adsorbents.

George Z. Kyzas

2014-01-01

184

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)

185

Configurational thermodynamics of alloyed nanoparticles with adsorbates.  

Science.gov (United States)

Changes in the chemical configuration of alloyed nanoparticle (NP) catalysts induced by adsorbates under working conditions, such as reversal in core-shell preference, are crucial to understand and design NP functionality. We extend the cluster expansion method to predict the configurational thermodynamics of alloyed NPs with adsorbates based on density functional theory data. Exemplified with PdRh NPs having O-coverage up to a monolayer, we fully detail the core-shell behavior across the entire range of NP composition and O-coverage with quantitative agreement to in situ experimental data. Optimally fitted cluster interactions in the heterogeneous system are the key to enable quantitative Monte Carlo simulations and design. PMID:25411918

Wang, Lin-Lin; Tan, Teck L; Johnson, Duane D

2014-12-10

186

Microstructure and biological properties of micro-arc oxidation coatings on ZK60 magnesium alloy.  

Science.gov (United States)

Ceramic coatings were prepared on ZK60 magnesium alloy in electrolyte with different concentration ratio of calcium and phosphorus (Ca/P) by micro-arc oxidation (MAO) technique at constant voltage. The microstructure, phase composition, elemental distribution, corrosion resistance, and adhesion of the coatings were investigated by scanning electron microscope (SEM), X-ray diffractometer (XRD), energy-dispersive X-ray spectrometry (EDS), electrochemical workstation, and scratch spectrometer, respectively. The coating biocompatibility was evaluated by in vitro cytotoxicity tests and systemic toxicity tests, and the bioactivity and degradability were evaluated by simulation body fluid (SBF) immersion tests. SEM shows that pores with different shapes distribute all over the coating surface. The adhesion and thickness of the coatings increases with increasing Ca/P ratio of electrolyte. The in vitro cytotoxicity tests and systemic toxicity texts demonstrate that the coatings have no toxicity to cell and living animal, which show that the coatings have excellent biocompatibility. XRD analysis shows that bioactive calciumphosphate (CaP) phases such as hydroxyapatite (HA, Ca(10)(PO(4))(6)(OH)(2)) and calcium pyrophosphate (CPP, Ca(2)P(2)O(7)) are induced in the immersed coatings, indicating that the MAO coatings have excellent bioactivity. PMID:22692915

Pan, Y K; Chen, C Z; Wang, D G; Yu, X

2012-08-01

187

Stability of plasma electrolytic oxidation coating on titanium in artificial saliva.  

Science.gov (United States)

Bioactive PEO coating on titanium with high Ca/P ratio was fabricated and characterized with respect to its morphology, composition and microstructure. Long-term electrochemical stability of the coating and Ti(4+) ion release was evaluated in artificial saliva. Influence of the lactic acid and fluoride ions on corrosion protection mechanism of the coated titanium was assessed using AC and DC electrochemical tests. The PEO-treated titanium maintained high passivity in the broad range of potentials up to 2.5 V (Ag/AgCl) for up to 8 weeks of immersion in unmodified saliva and exhibited Ti(4+) ion release <0.002 µg cm(-2) days(-1). The high corrosion resistance of the coating is determined by diffusion of reacting species through the coating and resistance of the inner dense part of the coating adjacent to the substrate. Acidification of saliva in the absence of fluoride ions does not affect the surface passivity, but the presence of 0.1 % of fluoride ions at pH ?4.0 causes loss of adhesion of the coating due to inwards migration of fluoride ions and their adsorption at the substrate/coating interface in the presence of polarisation. PMID:23073838

Matykina, E; Arrabal, R; Mohedano, M; Pardo, A; Merino, M C; Rivero, E

2013-01-01

188

Dry sliding wear behaviour of magnesium oxide and zirconium oxide plasma electrolytic oxidation coated magnesium alloy  

International Nuclear Information System (INIS)

Two types of PEO coatings, one consisting of magnesium oxide (MgO) and the other comprising zirconium oxide (ZrO2) as the main phase composition were produced on AM50 magnesium alloy from alkaline and acidic electrolytes, respectively. The ZrO2 coating was found to be spongy and thicker with a higher roughness, whilst the relatively more compact MgO coating was having contrasting features. In the dry sliding oscillating wear tests under two different loads viz., 2 N and 5 N, the ZrO2 coating exhibited a very poor wear resistance. The MgO coating showed an excellent resistance to sliding wear under 2 N load; however, the load bearing capacity of the coating was found to be insufficient to resist the wear damage under 5 N load. The higher specific wear rates of the MgO coating under 5 N load and that of the ZrO2 coating under 2 N and 5 N loads were attributed to the poor load bearing capacity and a three-body-abrasive wear mechanism.

189

Thickness effects on the mechanical properties of micro-arc discharge oxide coatings on aluminium alloys  

Energy Technology Data Exchange (ETDEWEB)

Weight-saving materials are becoming increasingly important, especially in the automotive and aerospace industries. Design engineers would thus like to make more extensive use of light metals such as aluminium, titanium, magnesium and their alloys; however, these materials tend to have poor wear resistance. Previous treatments and coatings applied to aluminium alloys, for example by traditional processes such as hard anodising and thermal spraying, have suffered from the low load support from the underlying material and/or insufficient adhesion, which reduces their durability. Also, although TiN-, CrN- or DLC-coated aluminium alloys (using various PVD methods) can achieve a high surface hardness, in practice they often exhibit poor performance under mechanical loading, since the coatings are usually too thin to protect the substrate from the contact conditions. In the work reported here, a plasma electrolysis technique known as micro-arc discharge oxidation (MDO) was investigated; thick and hard oxide ceramic layers were fabricated on BS Al-6082 aluminium alloy by this method. The phase composition and microstructure of the MDO coatings were investigated by XRD, SEM and EDX analyses. A number of adhesion and tribological sliding and impact wear tests were also performed. It was found that Al-Si-O coatings with a hardness of up to 2400 HV and with excellent wear resistance and load support could be formed. The thickness of the coatings significantly influenced the mechanical properties. In terms of tribological performance, the thicker coatings performed best in sliding, scratch and impact tests whilst thin coatings were also surprisingly effective in both impact and low-load sliding. Coatings of intermediate thickness provided relatively poor performance in all tribological tests. (orig.)

Nie, X.; Leyland, A. [Hull Univ. (United Kingdom). Research Centre in Surface Engineering; Song, H.W. [Institute of Low Energy Nuclear Physics, Beijing (China); Yerokhin, A.L. [Laboratory of Electrophysical and Electrochemical Treatment, Tula State University, Tula (Russian Federation); Dowey, S.J. [Ion Coat Ltd, Newlands House, Newlands Science Park, Hull (United Kingdom); Matthews, A. [Research Centre in Surface Engineering, University of Hull, Hull (United Kingdom)

1999-09-01

190

Osteoblast responses to different oxide coatings produced by the sol-gel process on titanium substrates.  

Science.gov (United States)

In order to improve the osseointegration of endosseous implants made from titanium, the structure and composition of the surface were modified. Mirror-polished commercially pure (cp) titanium substrates were coated by the sol-gel process with different oxides: TiO(2), SiO(2), Nb(2)O(5) and SiO(2)-TiO(2). The coatings were physically and biologically characterized. Infrared spectroscopy confirmed the absence of organic residues. Ellipsometry determined the thickness of layers to be approximately 100nm. High resolution scanning electron microscopy (SEM) and atomice force microscopy revealed a nanoporous structure in the TiO(2) and Nb(2)O(5) layers, whereas the SiO(2) and SiO(2)-TiO(2) layers appeared almost smooth. The R(a) values, as determined by white-light interferometry, ranged from 20 to 50nm. The surface energy determined by the sessile-drop contact angle method revealed the highest polar component for SiO(2) (30.7mJm(-2)) and the lowest for cp-Ti and 316L stainless steel (6.7mJm(-2)). Cytocompatibility of the oxide layers was investigated with MC3T3-E1 osteoblasts in vitro (proliferation, vitality, morphology and cytochemical/immunolabelling of actin and vinculin). Higher cell proliferation rates were found in SiO(2)-TiO(2) and TiO(2), and lower in Nb(2)O(5) and SiO(2); whereas the vitality rates increased for cp-Ti and Nb(2)O(5). Cytochemical assays showed that all substrates induced a normal cytoskeleton and well-developed focal adhesion contacts. SEM revealed good cell attachment for all coating layers. In conclusion, the sol-gel-derived oxide layers were thin, pure and nanostructured; consequent different osteoblast responses to those coatings are explained by the mutual action and coadjustment of different interrelated surface parameters. PMID:18440883

Ochsenbein, Anne; Chai, Feng; Winter, Stefan; Traisnel, Michel; Breme, Jürgen; Hildebrand, Hartmut F

2008-09-01

191

Enhanced capacitive performance of TiO2 nanotubes with molybdenum oxide coating  

International Nuclear Information System (INIS)

Highlights: • MoO3 was firstly deposited on TiO2 nanotubes for better supercapacitive behaviors. • Coated TiO2 nanotubes showed much higher capacitance than pure TiO2 or MoO3 films. • Deposition cycles were optimized to gain the best capacitance of MoO3/TiO2 hybrids. - Abstract: 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

192

Enhanced capacitive performance of TiO{sub 2} nanotubes with molybdenum oxide coating  

Energy Technology Data Exchange (ETDEWEB)

Highlights: • MoO{sub 3} was firstly deposited on TiO{sub 2} nanotubes for better supercapacitive behaviors. • Coated TiO{sub 2} nanotubes showed much higher capacitance than pure TiO{sub 2} or MoO{sub 3} films. • Deposition cycles were optimized to gain the best capacitance of MoO{sub 3}/TiO{sub 2} hybrids. - Abstract: Alpha-phase MoO{sub 3} is electrochemically deposited on well-aligned TiO{sub 2} nanotubes which are synthesized by anodic oxidation. The morphology, composition and electrochemical behaviors of MoO{sub 3}-coated and bare TiO{sub 2} nanotubes are studied. The former deliver greatly higher capacitance than the latter and their performance can be readily optimized by varying MoO{sub 3} deposition cycles. The large areal capacitance of 209.6 mF cm{sup ?2} at a scan rate of 5 mV s{sup ?1} is firstly achieved for TiO{sub 2} nanotube array electrode. In addition, the coated TiO{sub 2} nanotubes show significantly more capacitance than a dense MoO{sub 3} film. For example, they exhibit a capacitance up to 74.9 F g{sup ?1} at 5 mV s{sup ?1} in 1 M KCl solution, while the dense film only shows a capacitance of 32.3 F g{sup ?1} under same conditions. Such improvement is found ascribed to MoO{sub 3} with high pseudocapacity and TiO{sub 2} nanotubes with large surface area allowing efficient MoO{sub 3} 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, E-mail: cyuan@uwm.edu

2014-05-01

193

ACEP adsorbent structure and characteristics  

International Nuclear Information System (INIS)

The enrichment efficiency was investigated from the viewpoint of the kinetic characteristics of the adsorbent. In this study, in order to analyze the relationship between the diffusion coefficient and adsorbent structure, adsorbents with different pore diameters were prepared and their diffusion coefficients were measured. As a result, the diffusion coefficient was found to be significantly dependent on the pore diameter. In addition, adsorbents with pore diameters in excess of 30 nm were found to be highly efficient. Furthermore, the equilibrium height, Hq was measured under various conditions with different electron exchange reaction rates using adsorbents with highly controlled pore structures. The Hq, values observed were about ten times smaller than the calculated values using electron exchange rate constant ket in the solution. This fact implied the electron exchange reaction occurred mainly in the adsorbent. As a result, the ACEP adsorbent was found to need an highly controlled pore structure for the adsorption-desorption reaction and also the ability to accelerate the electron exchange reaction. ACEP adsorbents designed with this in mind were prepared on a semi-commercial scale and their high efficiency was proven in a semi-commercial enrichment plant at Hyuga. (author)

194

Introduce, research and testing of type ? adsorber  

International Nuclear Information System (INIS)

Introduce the theory and function of Type ? Adsorber. Briefly describe the Type ? Adsorber designed by Shanghai Nuclear Engineering and Design Institute, and its testing to prove that the Type ? Adsorber has the advantages comparing with Type ? and ? Adsorbers. Also prove that the Type ? Adsorber designed by Shanghai Nuclear Engineering and Design Institute can be used in AP1000 and other nuclear power plants. (authors)

195

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

196

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

197

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

198

Krypton retention on solid adsorbents  

International Nuclear Information System (INIS)

Radioactive krypton-85 is released to the atmosphere in the off-gas from nuclear reprocessing plants. Three main methods have been suggested for removal of krypton from off-gas streams: cryogenic distillation; fluorocarbon absorption; and adsorption on solid sorbents. Use of solid adsorbents is the least developed of these methods, but offers the potential advantages of enhanced safety and lower operating costs. An experimental laboratory program was developed that will be used to investigate systematically many solid adsorbents (such as zeolites, i.e., mordenites) for trapping krypton in air. The objective of this investigation is to find an adsorbent that is more economical than silver-exchanged mordenite. Various physical and chemical characteristics such as adsorption isotherms, decontamination factors, co-adsorption, regeneration, and the mechanism and kinetics of noble gas adsorption were used to characterize the adsorbents. In the experimental program, a gas chromatograph using a helium ionization detector was used to measure the krypton in air before and after the adsorbent bed. This method can determine directly decontamination factors greater than 100

199

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

200

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)

201

Carbon nanotubes - the promising adsorbent in wastewater treatment  

International Nuclear Information System (INIS)

Carbon materials are a class of significant and widely used engineering adsorbent. As a new member of the carbon family, carbon nanotubes have exhibited great potentials in applications as composite reinforcements, field emitters for flat panel display, sensors, energy storage and energy conversion devices, and catalysts support phases, because of their extraordinary mechanical, electrical, thermal and structural properties. In particular, the large specific surface areas, as well as the high chemical and thermal stabilities, make carbon nanotubes an attractive adsorbent in wastewater treatment. The adsorption properties of the carbon nanotubes to a series of toxic agents, such as lead, cadmium and 1, 2-dichlorobenzene have been studied and the results show that carbon nanotubes are excellent and effective adsorbent for eliminating these harmful media in water. The effects of the morphologies and the surface status on the carbon nanotube adsorption capacities are also discussed

202

Uranium Recovery from Seawater: Development of Fiber Adsorbents Prepared via Atom-Transfer Radical Polymerization  

Energy Technology Data Exchange (ETDEWEB)

A novel adsorbent preparation method using atom-transfer radical polymerization (ATRP) combined with radiation-induced graft polymerization (RIGP) was developed to synthesize an adsorbent for uranium recovery from seawater. The ATRP method allowed a much higher degree of grafting on the adsorbent fibers (595 2818%) than that allowed by RIGP alone. The adsorbents were prepared with varied composition of amidoxime groups and hydrophilic acrylate groups. The successful preparation revealed that both ligand density and hydrophilicity were critical for optimal performance of the adsorbents. Adsorbents synthesized in this study showed a relatively high performance (141 179 mg/g at 49 62 % adsorption) in laboratory screening tests using a uranium concentration of ~6 ppm. This performance is much higher than that of known commercial adsorbents. However, actual seawater experiment showed impeded performance compared to the recently reported high-surface-area-fiber adsorbents, due to slow adsorption kinetics. The impeded performance motivated an investigation of the effect of hydrophilic block addition on the graft chain terminus. The addition of hydrophilic block on the graft chain terminus nearly doubled the uranium adsorption capacity in seawater, from 1.56 mg/g to 3.02 mg/g. The investigation revealed the importance of polymer chain conformation, in addition to ligand and hydrophilic group ratio, for advanced adsorbent synthesis for uranium recovery from seawater.

Saito, Tomonori [ORNL; Brown, Suree [ORNL; Chatterjee, Sabornie [ORNL; Kim, Jungseung [ORNL; Tsouris, Costas [ORNL; Mayes, Richard T [ORNL; Kuo, Li-Jung [Pacific Northwest National Laboratory (PNNL); Gill, Gary [Pacific Northwest National Laboratory (PNNL); Oyola, Yatsandra [ORNL; Janke, Christopher James [ORNL; Dai, Sheng [ORNL

2014-01-01

203

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

OpenAIRE

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

204

Adsorption chemiluminescence on ?-irradiated adsorbents  

International Nuclear Information System (INIS)

The adsorption chemiluminescence effect has been studied taking place when O2, CO2, H2 or NH2 are contacted with a number of irradiated adsorbents. The ?-irradiated samples of Al2O3-SiO2, SiO2, Al2O3, MgO-SiO2, ZrO2-SiO2 and zeolite NaY samples have been used to investigate adsorboluminescence. Certain regularities of adsorboluminescence have been established

205

Electrochemical corrosion behaviour of plasma electrolytic oxidation coatings on AM50 magnesium alloy formed in silicate and phosphate based electrolytes  

International Nuclear Information System (INIS)

PEO coatings were produced on AM50 magnesium alloy by plasma electrolytic oxidation process in silicate and phosphate based electrolytes using a pulsed DC power source. The microstructure and composition of the PEO coatings were analyzed by scanning electron microscopy (SEM) and X-ray Diffraction (XRD). The corrosion resistance of the PEO coatings was evaluated using open circuit potential (OCP) measurements, potentiodynamic polarisation tests and electrochemical impedance spectroscopy (EIS) in 0.1 M NaCl solution. It was found that the electrolyte composition has a significant effect on the coating evolution and on the resulting coating characteristics, such as microstructure, composition, coating thickness, roughness and thus on the corrosion behaviour. The corrosion resistance of the PEO coating formed in silicate electrolyte was found to be superior to that formed in phosphate electrolyte in both the short-term and long-term electrochemical corrosion tests.

206

Synthesis and Characterization of Adsorbent for Pb(II)-capture by using Glow Discharge Electrolysis Plasma  

International Nuclear Information System (INIS)

A novel polyacrylamide grafted hydrous ferric oxide adsorbent composite has been synthesized by using glow discharge electrolysis plasma. To optimize the synthesis conditions, the following parameters were examined in detail: applied power, discharge time, post polymerization temperature, post polymerization time, amount of crosslinking agent and hydrous ferric oxide gel added and so on. The adsorbent was characterized by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The removal percentage of the adsorbent in Pb(II) solution was examined and the data obtained showed that the adsorbent composite has a high capacity for lead ion. For the use in wastewater treatment, the thermodynamic and kinetic of Pb(II)-capture were also studied. Results indicated that the adsorption reaction was a spontaneous and an endothermic process, and it seems to be obeyed a pseudo-secondorder rate model. Moreover, the adsorption isotherm of Pb(II)-capture is following the Langmuir and Freundlich isotherm models

207

A novel color removal adsorbent from heterocoagulation of cationic and anionic clays.  

Science.gov (United States)

We report the preparation and characterization of a novel nanocomposite adsorbent for anionic dye removal. The nanocomposite adsorbent was prepared by heterocoagulation of delaminated bentonite and layered double hydroxide (LDH) colloids. The effects of preparation conditions, LDH loading, particle size, and calcination temperature of the modified material on the physicochemical properties of this composite adsorbent have been investigated. The optimal conditions for best Reactive Yellow 2 (RY2) dye removal efficiency are a weight ratio of LDH to bentonite of 1:1, LDH particle size 100 nm, and calcination temperature 673 K. The adsorption equilibrium data can be fitted well by the widely accepted adsorption isotherm models. PMID:17257613

Hu, Qiuhong; Xu, Zhiping; Qiao, Shizhang; Haghseresht, Fouad; Wilson, Michael; Lu, Gao Qing

2007-04-01

208

Displacement of adsorbed polymers. A systematic study of segment-surface interactions.  

OpenAIRE

This thesis describes a method to determine the thermodynamic (reversible) adhesion strength of polymers on inorganic solids.This adhesion strength of polymers is an important factor in many applications. Examples are the quality and properties of glass fibre reinforced composites, coatings, and adhesives.The key idea of the method is that the thermodynamic adhesion strength can be obtained from polymer displacement experiments. Polymers adsorbed from solution on an inorganic adsorbent can be...

Beek, G. P.

1991-01-01

209

A novel fiber-based adsorbent technology  

International Nuclear Information System (INIS)

In this Phase I Small Business Innovation Research program, Chemica Technologies, Inc. is developing an economical, robust, fiber-based adsorbent technology for removal of heavy metals from contaminated water. The key innovation is the development of regenerable adsorbent fibers and adsorbent fiber cloths that have high capacity and selectivity for heavy metals and are chemically robust. The process has the potential for widespread use at DOE facilities, mining operations, and the chemical process industry

210

A novel fiber-based adsorbent technology  

Energy Technology Data Exchange (ETDEWEB)

In this Phase I Small Business Innovation Research program, Chemica Technologies, Inc. is developing an economical, robust, fiber-based adsorbent technology for removal of heavy metals from contaminated water. The key innovation is the development of regenerable adsorbent fibers and adsorbent fiber cloths that have high capacity and selectivity for heavy metals and are chemically robust. The process has the potential for widespread use at DOE facilities, mining operations, and the chemical process industry.

Reynolds, T.A. [Chemica Technologies, Inc., Bend, OR (United States)

1997-10-01

211

Molecular filtration : the study of adsorbents  

OpenAIRE

Adsorbent materials for gas purification have been studied and developed for application in many areas. It is known that a single adsorbent may not adequately control multiple contaminants. Therefore, the development of adsorbent materials has accelerated over the past two decades, and is today an area attracting a lot of attention. In view of the global environmental movement for clean air, the development of improved sorbents will help address new challenges that cannot efficiently be met w...

Twumasi, Ebenezer

2011-01-01

212

Fabrication and Characterization of Antimony―doped Tin Oxide Coating Diatomite Conductive Material with Microporous Structure  

Directory of Open Access Journals (Sweden)

Full Text Available Porous and conductive diatomite composite materials were prepared via the calcination of the Sb―SnO2―coated diatomite precursor derived from the co―precipitation route with diatomite as the substrate. Conductivity of the samples was influenced by the Sb―SnO2 coating ratio. Calcination temperature had an impact on the crystal lattice parameters and grain sizes, hence altering the conductivity and resistivity of the composite materials. The samples were characterized by means of X―ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), energy―dispersive X―ray spectrometry (EDS), N2 adsorption―desorption measurement (BET), and Fourier transform infrared spectrometry (FT―IR). The conductive performance of the samples was determined using a Four―Point Probe Meter apparatus. It is shown that the mesoporous (pore diameter = 6 nm) sample with n(Sn)/n(Sb)=8/1 and a Sb―SnO2 coating ratio of 25.8wt% derived from calcination at 700¡?xhibited the lowest resistivity of 22 ?·cm.

DU Yu-Cheng, YAN Jing, MENG Qi, LI Yang, DAI Hong-Xing

2011-10-01

213

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

214

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

215

Effects of cathodic voltages on structure and wear resistance of plasma electrolytic oxidation coatings formed on aluminium alloy  

Science.gov (United States)

Plasma electrolytic oxidation (PEO) coatings were prepared on aluminium alloy using pulsed bipolar power supply at constant anodic voltage and different cathodic voltages. The samples were prepared to attain the same coating thickness by adjusting the processing time. The scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and tribometer were employed to investigate the microstructure, element content, phase composition and wear resistance of the coatings respectively. It was found that the coating growth rate enhanced obviously and the coatings exhibited a more compact structure with thicker inner layer and lower surface roughness when the cathodic voltage increased. The coatings were mainly composed of crystalline ?-Al2O3 and amorphous silicate oxides and their relative content changed with the cathodic voltage. The wear resistance of the coatings improved significantly with the increase of cathodic voltage.

Li, Qingbiao; Liang, Jun; Liu, Baixing; Peng, Zhenjun; Wang, Qing

2014-04-01

216

Ecological applications of the irradiated adsorbents  

International Nuclear Information System (INIS)

Full text: In our previous works it was shown that after irradiation some adsorbents gain new interesting properties such as increasing (or decreasing) of their adsorption capacity, selectivity in relation to some gases, change of chemical bounds of gas molecules with adsorbent surface as well as other properties. We investigated a lot of adsorbents with semiconducting and dielectric properties. A high temperature superconductor was investigated also. Adsorbents were irradiated by ultraviolet (UV) and gamma - radiation, reactor (n.?) - radiation, ?-particles (E=40-50 MeV), protons ( E=30 MeV), and also He-3 ions (E-29-60 MeV). The following techniques were used: volumetric (manometrical), mass-spectrometer and IR spectroscopic methods, and also method of electronic - paramagnetic resonance (spin paramagnetic resonance) The obtained results allow to speak about creation of new adsorbents for gas purification (clearing) from harmful impurities, gas selection into components, an increasing of adsorbing surface. Thus one more advantage of the irradiated adsorbents is that they have 'memory effect', i.e. they can be used enough long time after irradiation. In laboratory conditions we built the small-sized adsorptive pump on the basis of the irradiated zeolites which are capable to work in autonomous conditions. It was found, that some of adsorbents after irradiation gain (or lose) selectivity in relation to definite gases. So, silica gel, which one in initial state does not adsorb hydrogen, after gamma irradiation it becomes active in relation to hydrogen. Some of rare earths oxides also show selectivity in relation to hydrogen and oxygen depending on a type of irradiation. Thus, it is possible to create different absorbents, depending on a solved problem, using a way or selection of adsorbents, either of radiation type and energy, as a result obtained adsorbents can be used for various ecological purposes

217

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

218

Filter-adsorber aging assessment  

International Nuclear Information System (INIS)

An aging assessment of high-efficiency particulate (HEPA) air filters and activated carbon gas adsorption units was performed by the Pacific Northwest Laboratory as part of the U.S. Nuclear Regulatory Commission's (USNRC) Nuclear Plant Aging Research (NPAR) Program. This evaluation of the general process in which characteristics of these two components gradually change with time or use included the compilation of information concerning failure experience, stressors, aging mechanisms and effects, and inspection, surveillance, and monitoring methods (ISMM). Stressors, the agents or stimuli that can produce aging degradation, include heat, radiation, volatile contaminants, and even normal concentrations of aerosol particles and gasses. In an experimental evaluation of degradation in terms of the tensile breaking strength of aged filter media specimens, over forty percent of the samples did not meet specifications for new material. Chemical and physical reactions can gradually embrittle sealants and gaskets as well as filter media. Mechanisms that can lead to impaired adsorber performance are associated with the loss of potentially available active sites as a result of the exposure of the carbon to airborne moisture or volatile organic compounds. Inspection, surveillance, and monitoring methods have been established to observe filter pressure drop buildup, check HEPA filters and adsorbers for bypass, and determine the retention effectiveness of aged carbon. These evaluatifectiveness of aged carbon. These evaluations of installed filters do not reveal degradation in terms of reduced media strength but that under normal conditions aged media can continue to effectively retain particles. However, this degradation may be important when considering the likelihood of moisture, steam, and higher particle loadings during severe accidents and the fact it is probable that the filters have been in use for an extended period

219

Thermodynamics of gas adsorption on solid adsorbents  

International Nuclear Information System (INIS)

Starting with several hypotheses about the adsorbtion system and the adsorption phenomenon, a thermodynamic treatment of gas adsorption on solid adsorbants is presented. The relationships for determination from isotherms and calorimetric data of thermodynamic functions are derived. The problem of the phase changes in adsorbed layer is discussed. (author)

220

Effects of cathodic voltages on structure and wear resistance of plasma electrolytic oxidation coatings formed on aluminium alloy  

Energy Technology Data Exchange (ETDEWEB)

Highlights: • The PEO coating growth rate increased with the cathodic voltage increasing. • Higher cathodic voltage resulted in more compact coating structure. • The compact structure led to low surface roughness and high wear resistance. - Abstract: Plasma electrolytic oxidation (PEO) coatings were prepared on aluminium alloy using pulsed bipolar power supply at constant anodic voltage and different cathodic voltages. The samples were prepared to attain the same coating thickness by adjusting the processing time. The scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and tribometer were employed to investigate the microstructure, element content, phase composition and wear resistance of the coatings respectively. It was found that the coating growth rate enhanced obviously and the coatings exhibited a more compact structure with thicker inner layer and lower surface roughness when the cathodic voltage increased. The coatings were mainly composed of crystalline ?-Al{sub 2}O{sub 3} and amorphous silicate oxides and their relative content changed with the cathodic voltage. The wear resistance of the coatings improved significantly with the increase of cathodic voltage.

Li, Qingbiao [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); School of Science, Lanzhou University of Technology, Lanzhou 730050 (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); Liu, Baixing; Peng, Zhenjun [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Wang, Qing [School of Science, Lanzhou University of Technology, Lanzhou 730050 (China)

2014-04-01

221

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

222

Effects of cathodic voltages on structure and wear resistance of plasma electrolytic oxidation coatings formed on aluminium alloy  

International Nuclear Information System (INIS)

Highlights: • The PEO coating growth rate increased with the cathodic voltage increasing. • Higher cathodic voltage resulted in more compact coating structure. • The compact structure led to low surface roughness and high wear resistance. - Abstract: Plasma electrolytic oxidation (PEO) coatings were prepared on aluminium alloy using pulsed bipolar power supply at constant anodic voltage and different cathodic voltages. The samples were prepared to attain the same coating thickness by adjusting the processing time. The scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and tribometer were employed to investigate the microstructure, element content, phase composition and wear resistance of the coatings respectively. It was found that the coating growth rate enhanced obviously and the coatings exhibited a more compact structure with thicker inner layer and lower surface roughness when the cathodic voltage increased. The coatings were mainly composed of crystalline ?-Al2O3 and amorphous silicate oxides and their relative content changed with the cathodic voltage. The wear resistance of the coatings improved significantly with the increase of cathodic voltage

223

The phase and microstructural analysis of protective oxide coatings on molybdenum; Phasen- und Gefuegeanalyse in Oxidationsschutzschichten fuer Molybdaen  

Energy Technology Data Exchange (ETDEWEB)

Due to their high sensitivity to oxygen, the use of refractory metals requires an effective protection against oxidation. In the case of molybdenum this is achieved by using a silicon and boron based coating commercially marketed under the trade name SIBOR {sup registered}. In the moduction of a SIBOR {sup registered} -coating, a mixture of Si, B and C is plasma sprayed in air onto the Mo-surface to be protected and subsequently annealed in hydrogen. Previous investigations have shown that in doing so a stationary coating of Mo-borides and Mo-silicides is formed. However, the exact phase arrangement and composition has until now remained unclear. Energy dispersive X-ray spectroscopy (EDS) in the scanning electron microscope (SEM) is able to analyse the silicides in SIBOR {sup registered}, although due to the overlapping of the Mo-and B-spectral partial a clear identification of the borides was not possible. Using a combination of electron back scatter diffraction (EBSD) and wavelength dispersive X-ray spectroscopy (WDS) it is, however, shown that SIBOR {sup registered} is made up of a series of sublayers of Mo{sub 2}B and MoB followed by Mo{sub 5}Si{sub 3} and MoSi{sub 2}, and that the other phases of the Mo-Si-B ternary system, i.e. Mo{sub 3}Si and Mo{sub 5}SiB{sub 2}(T{sub 2}), do not occur. Notably, the two borides and the Mo{sub 5}Si{sub 3} exhibit a structure which is polycrystalline in the lateral direction yet normal to the surface forms of only a single layer of crystallites. In contrast, the final MoSi{sub 2}-layer has a polycrystalline structure both in the lateral and in the normal directions. Furthermore, Mo{sub 5}Si{sub 3} and MoSi{sub 2} both exhibit marked textures. (orig.)

Traxler, Hannes; Joerg, Roland; Zabernig, M; Sigl, L.S. [PLANSEE SE, Reutte /Tirol (Austria)

2011-07-01

224

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

225

Composites  

Science.gov (United States)

The Composites market is arguably the most challenging and profitable market for phenolic resins aside from electronics. The variety of products and processes encountered creates the challenges, and the demand for high performance in critical operations brings value. Phenolic composite materials are rendered into a wide range of components to supply a diverse and fragmented commercial base that includes customers in aerospace (Space Shuttle), aircraft (interiors and brakes), mass transit (interiors), defense (blast protection), marine, mine ducting, off-shore (ducts and grating) and infrastructure (architectural) to name a few. For example, phenolic resin is a critical adhesive in the manufacture of honeycomb sandwich panels. Various solvent and water based resins are described along with resin characteristics and the role of metal ions for enhanced thermal stability of the resin used to coat the honeycomb. Featured new developments include pultrusion of phenolic grating, success in RTM/VARTM fabricated parts, new ballistic developments for military vehicles and high char yield carbon-carbon composites along with many others. Additionally, global regional market resin volumes and sales are presented and compared with other thermosetting resin systems.

Taylor, John G.

226

Composites  

Science.gov (United States)

Ca3Co4O9 is one of the most promising p-type thermoelectric materials because of its high dimensionless figure of merit ZT. However, polycrystalline Ca3Co4O9 ceramics shows lower ZT value than that for single crystal Ca3 Co4O9 due to its higher electrical resistivity ?. Mikami et al. have reported that the addition of Ag to Ca3Co4O9 ceramics could successfully reduce ? and enhance the power factor. On the other hand, Ohtaki et al. reported that a composite structure could be highly effective to reduce ? for ZnO dually doped with Al and Ga. In this work, we tried to enhance the power factor and reduce ? by forming Ca3Co4O9/[Ca2(Co0.65Cu0.35)2O4]0.624CoO2 composite structure. As a result, the ZT value for Ca3Co4O9/[Ca2(Co0.65Cu0.35)2O4]0.624CoO2 composites reached 0.164 at 700 °C, which was 40 % higher than the value for Ca3Co4O9.

Obata, Kohei; Chonan, Yasunori; Komiyama, Takao; Abe, Kazunori; Aoyama, Takashi; Yamaguchi, Hiroyuki; Sugiyama, Shigeaki

2014-06-01

227

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

228

Preparation of adsorbent from quartz porphyry : NaOH activation  

Energy Technology Data Exchange (ETDEWEB)

Quartz porphyry with micro porosity has a property to resolve and adsorb heavy heavy metal, bacillus and toxic substance like copper or chromium. For this reason, it has been used for removing harmful substance in our body. The adsorbent was prepared from powder of quartz porphyry by chemical activation with NaOH. The following processes were carried out ; firing step and chemical activation or physical activation step. The firing step was carried out at 600 degree C fir one hour in air. The activation temperature, the activation time and the chemical ratio of activation agents were optimized in the chemical activation step. By using BET and Langmuir equations, specific surface areas of activated quartz porphyry prepared by chemical activation with NaOH were measured to be about 220-389 m{sup 2}/g and 320-565 m{sup 2}/g. The main composition of quartz porphyry were Si, Al, Fe and Ca. The surface area of natural quartz porphyry is lower than that of silica gel or zeolite, But increase of surface area by activation and homogeneity of pore size lead to new high-surface area adsorbent. 20 refs., 14 figs., 2 tabs.

Kim, Hak Hee; Park, Sin Kyong [Division of Chemical Engineering, Sunmoon University, Ansan (Korea); Chung, Kwang Bo [Department of Chemical Engineering, Hanseo University, Seosan (Korea); Chang, Seung Hyun [Department of Chemistry, Taegu University, Kyoungsan (Korea)

2000-04-01

229

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

230

Inorganic chemically active adsorbents (ICAAs)  

Energy Technology Data Exchange (ETDEWEB)

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.

Ally, M.R. [Oak Ridge National Lab., TN (United States); Tavlarides, L.

1997-10-01

231

Synthesis of Polypropylene Fiber/Hydrated Iron Oxide Nanocomposite Adsorbent  

Directory of Open Access Journals (Sweden)

Full Text Available Composite adsorbent based on the polypropylene fibers with chemically bound nanoparticles of hydrated iron (III oxide were synthesized by two-stage experiment: radiation-induced graft polymerization of acrylic acid onto the surface of polypropylene fibers followed by the in-situ formation of hydrated iron oxide nanoparticles and their stabilization on the fibers’ surface within the grafted layer. SEM and XRD investigations revealed a compact homogeneous layer of amorphous nanoaggregates (70-100 nm formed by iron hydroxide on the fibers’ surface. The synthesized nanocomposite fibers were stable in the aggressive medium for a long time and exhibited good adsorption properties for uranyl ions.

Bondar I.V.

2013-09-01

232

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

233

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

234

Zeolites as alcohol adsorbents from aqueous solutions  

OpenAIRE

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...

Cekova Blagica; Kocev Dragi; Kolcakovska Elena; Stojanova Daniela

2006-01-01

235

Defluoridization Using a Natural Adsorbent, Strychnos Potatorum  

OpenAIRE

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

236

Zircaloy Oxidation in Air: Effects of Adsorbates  

International Nuclear Information System (INIS)

The air oxidation of Zry and the effects of adsorbates on the oxidation are found by the intermittent measurements of the weight gain of specimens. LiOH and NaCl are the adsorbates tested in this paper. NaCl enhances the oxidation, where nonuniform stresses on the surface and Cl ions are the cause of the enhancement. LiOH also enhances the oxidation, where initial porous oxide seem to the reason

237

Characterization of thin films and surface adsorbates by laser-induced thermal desorption with FTMS detection  

International Nuclear Information System (INIS)

Identifying the molecular species adsorbed on a surface is a difficult analytical problem which is important in studies of heterogeneous catalysis, corrosion, and surface contamination. Most surface analytical methods reveal very little about the molecular identity of an adsorbate. For example, Auger electron spectroscopy (AES) reveals only the elemental composition of a surface, and surface spectroscopic techniques such as electron energy loss spectroscopy and Raman spectroscopy lack the sensitivity and specificity that is needed to identify complex molecular adsorbates, particularly if there is a mixture of several species present. This talk will describe their efforts to develop the techniques of laser-induced thermal desorption (LITD) and Fourier transform mass spectrometry to characterize molecular species adsorbed on surfaces. Their approach has been to use low laser power densities to desorb neutral molecular species and post-ionization with an electron beam to produce mass spectra. Data will be presented on the characterization of the surface of a computer magnetic hard disk using AES, XPS, and LITD. AES and XPS reveal the elemental composition of the surface, and LITD is shown to be useful for identifying a variety of molecular species adsorbed on the surface

238

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

239

Novel Fiber-Based Adsorbent Technology; FINAL  

International Nuclear Information System (INIS)

The overall of this Department of Energy (DOE) Phase II SBIR program was to develop a new class of highly robust fiber-based adsorbents for recovery of heavy metals from aqueous waste-streams. The fiber-based adsorbents,when commercialized,will be used for clean up metals in aqueous waste-streams emanating from DOE facilities,industry,mining,and groundwater-cleanup operations.The amount of toxic waste released by these streams is of great significance.The U.S.Environment Protection Agency (EPA) reports that in 1990 alone,4.8 billion pounds of toxic chemicals were released into the environment.Of this waste,the metals-containing waste was the second largest contributor,representing 569 million pounds. This report presents the results of the Phase II program,which successfully synthesized noval fiber-based adsorbents for the removal of Group 12 metals(i.e.mercury),Group 14 metals (lead),and Group 10 metals(platinum and palladium) from contaminated groundwater and industrial waste streams.These fiber-based adsorbents are ideally suited for the recovery of metal ions from aqueous waste streams presently not treatable due to the degrading nature of corrosive chemicals or radioactive components in the feed stream. The adsorbents developed in this program rely on chemically resistant and robust carbon fibers and fabrics as supports for metal-ion selective ligands.These adsorbents demonstrate loading capacities and selectivities for metal ions exceeding those of conventional etal ions exceeding those of conventional ion-exchange resins.The adsorbents were also used to construct filter modules that demonstrate minimal fouling,minimal compaction,chemical and physical robustness,and regeneration of metal loading capacity without loss of performance

240

Method for modifying trigger level for adsorber regeneration  

Science.gov (United States)

A method for modifying a NOx adsorber regeneration triggering variable. Engine operating conditions are monitored until the regeneration triggering variable is met. The adsorber is regenerated and the adsorbtion efficiency of the adsorber is subsequently determined. The regeneration triggering variable is modified to correspond with the decline in adsorber efficiency. The adsorber efficiency may be determined using an empirically predetermined set of values or by using a pair of oxygen sensors to determine the oxygen response delay across the sensors.

Ruth, Michael J.; Cunningham, Michael J.

2010-05-25

241

Electrochemical behavior of LiFePO4 cathode materials in the presence of anion adsorbents  

International Nuclear Information System (INIS)

The poor rate capability is a major problem of olivine-structured lithium iron phosphate (LFP) cathode material in lithium-ion batteries due to its low electric conductivity and sluggish lithium diffusion. Other than the custom strategies to solve this problem like carbon coating and nano-size treatment, we simply mixed LFP with some anion adsorbents, which can store anions from the electrolytes swiftly. The effect of anion adsorbents on the performance of LFP composite electrode has been investigated by cyclic voltammetric tests and the corresponding apparent lithium diffusion coefficients have been measured

242

The Dynamics and Structures of Adsorbed Surfaces  

DEFF Research Database (Denmark)

Reviews neutron scattering work performed on films of simple gas atoms and molecules adsorbed primarily on graphite surfaces. Exfoliated graphite substrates such as Grafoil were first used in this kind of measurements about five years ago and new results have been reported at an increasing pace. Elastic neutron diffraction measurements, determining the two-dimensional structural ordering of the adsorbed films, have been performed on layers of N2, Ar, H2, D2, O2, Kr, and He. Measurements on layers of larger molecules such as CD4 and ND3 have also been reported. Inelastic neutron scattering measurements, studying the dynamics of the adsorbed films are only possible in a few especially favourable cases such as 36Ar and D2 films, where the coherent phonon scattering cross-sections are very large. In other cases incoherent scattering from hydrogen can give information about e.g. the mobility of molecules such as NH3 or the internal modes of adsorbed molecules such as C4H10. Neutron scattering measurements where substrates other than graphite products are used as the adsorbents will not be reviewed here. However, the power of the technique will be demonstrated in an example of H2 physisorbed to activated alumina and in an example where hydrogen is chemisorbed to Raney nickel

Nielsen, M; Ellenson, W. D.

1978-01-01

243

Black molecular adsorber coatings for spaceflight applications  

Science.gov (United States)

The molecular adsorber coating is a new technology that was developed to mitigate the risk of on-orbit molecular contamination on spaceflight missions. The application of this coating would be ideal near highly sensitive, interior surfaces and instruments that are negatively impacted by outgassed molecules from materials, such as plastics, adhesives, lubricants, epoxies, and other similar compounds. This current, sprayable paint technology is comprised of inorganic white materials made from highly porous zeolite. In addition to good adhesion performance, thermal stability, and adsorptive capability, the molecular adsorber coating offers favorable thermal control characteristics. However, low reflectivity properties, which are typically offered by black thermal control coatings, are desired for some spaceflight applications. For example, black coatings are used on interior surfaces, in particular, on instrument baffles for optical stray light control. Similarly, they are also used within light paths between optical systems, such as telescopes, to absorb light. Recent efforts have been made to transform the white molecular adsorber coating into a black coating with similar adsorptive properties. This result is achieved by optimizing the current formulation with black pigments, while still maintaining its adsorption capability for outgassing control. Different binder to pigment ratios, coating thicknesses, and spray application techniques were explored to develop a black version of the molecular adsorber coating. During the development process, coating performance and adsorption characteristics were studied. The preliminary work performed on black molecular adsorber coatings thus far is very promising. Continued development and testing is necessary for its use on future contamination sensitive spaceflight missions.

Abraham, Nithin S.; Hasegawa, Mark M.; Straka, Sharon A.

2014-09-01

244

Adsorbate diffusion on transition metal nanoparticles.  

Science.gov (United States)

Diffusion of adsorbates on transition metal nanoparticles is a precursor process for heterogeneously catalyzed reactions, and as a result, an atomistic understanding of the diffusion mechanism is very important. We systematically studied adsorption and diffusion of atomic and diatomic species (H, C, N, O, CO, and NO) on nanometer-sized Pt and Cu nanoparticles with different sizes and shapes using density functional theory calculations. We show that nanoparticles bind adsorbates more strongly than the corresponding extended single crystal metal surfaces. We find that there is a Brønsted-Evans-Polanyi-type linear correlation between the transition state energy and the initial state energy for adsorbate diffusion across the edges of Pt and Cu nanoparticles. We further show that the barrier for adsorbate diffusion across the nanoparticles edges can be estimated by the binding energy of the adsorbate on the nanoparticles. These results provide useful insights for understanding diffusion-mediated chemical reactions catalyzed by transition metal nanoparticles, which are widely used in heterogeneous catalysis. PMID:25422876

Peng, Guowen; Mavrikakis, Manos

2015-01-14

245

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

246

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

247

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

248

Preparation and tribological properties of self-lubricating TiO2/graphite composite coating on Ti6Al4V alloy  

Science.gov (United States)

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; Zhou, Xinjian; Xiao, Qian; Liang, Jun; Huo, Xiaodi

2012-09-01

249

Adsorption of gases by microporous adsorbents  

International Nuclear Information System (INIS)

The analysis of the previously performed investigations on adsorption of nitrogen, krypton and xenon by microporous carbon adsorbents. It is shown that Kr and Xe adsorption on active carbons with relatively small micropores at above critical temperatures (209-323.2 K) is satisfactorily described on the basis of the theory of volume micropore filling and assumption on linearity of adsorption isosteres. Using as adsorbents active carbons with larger micropores substantial deviations of calculational and experimental values are noted which is due to more significant changes with tempe-- rature of limiting adsorption values a0 for the second type of carbons

250

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

251

Waste metal hydroxide sludge as adsorbent for a reactive dye.  

Science.gov (United States)

An industrial waste sludge mainly composed by metal hydroxides was used as a low-cost adsorbent for removing a reactive textile dye (Remazol Brilliant Blue) in solution. Characterization of this waste material included chemical composition, pH(ZPC) determination, particle size distribution, physical textural properties and metals mobility under different pH conditions. Dye adsorption equilibrium isotherms were determined at 25 and 35 degrees C and pH of 4, 7 and 10 revealing reasonably fits to Langmuir and Freundlich models. At 25 degrees C and pH 7, Langmuir fit indicates a maximum adsorption capacity of 91.0mg/g. An adsorptive ion-exchange mechanism was identified from desorption studies. Batch kinetic experiments were also conducted at different initial dye concentration, temperature, adsorbent dosage and pH. A pseudo-second-order model showed good agreement with experimental data. LDF approximation model was used to estimate homogeneous solid diffusion coefficients and the effective pore diffusivities. Additionally, a simulated real effluent containing the selected dye, salts and dyeing auxiliary chemicals, was also used in equilibrium and kinetic experiments and the adsorption performance was compared with aqueous dye solutions. PMID:17976902

Santos, Sílvia C R; Vílar, Vítor J P; Boaventura, Rui A R

2008-05-30

252

Prussian blue caged in spongiform adsorbents using diatomite and carbon nanotubes for elimination of cesium  

Energy Technology Data Exchange (ETDEWEB)

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

Hu, Baiyang [Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810 (Japan); Fugetsu, Bunshi, E-mail: hu@ees.hokudai.ac.jp [Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810 (Japan); Yu, Hongwen [Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810 (Japan); Abe, Yoshiteru [Kyoei Engineering Corporation, Niigata 959-1961 (Japan)

2012-05-30

253

The biogeochemical cycle of the adsorbed template. II - Selective adsorption of mononucleotides on adsorbed polynucleotide templates  

Science.gov (United States)

Experimental results are presented for the verification of the specific interaction step of the 'adsorbed template' biogeochemical cycle, a simple model for a primitive prebiotic replication system. The experimental system consisted of gypsum as the mineral to which an oligonucleotide template attaches (Poly-C or Poly-U) and (5-prime)-AMP, (5-prime)-GMP, (5-prime)-CMP and (5-prime)-UMP as the interacting biomonomers. When Poly-C or Poly-U were used as adsorbed templates, (5-prime)-GMP and (5-prime)-AMP, respectively, were observed to be the most strongly adsorbed species.

Lazard, Daniel; Lahav, Noam; Orenberg, James B.

1988-01-01

254

NUCLEAR MAGNETISM OF ADSORBED 3He  

OpenAIRE

The nuclear magnetism of atomic layers of 3He adsorbed on graphite has been studied by NMR measurements of the magnetization, line shifts and thermal time constants. The properties of this novel system are well described by the two-dimensional ferromagnetic Heisenberg Hamiltonian.

Godfrin, H.; Ruel, R.; Osheroff, D.

1988-01-01

255

Desorption behavior of lithium from granulated adsorbent  

International Nuclear Information System (INIS)

The desorption properties of lithium was investigated by both a batch and a column method using granulated adsorbent (diameter 0.7-1.0mm) with a lithium content of 16.5 mg·g-1 at 25degC. The batch study showed that 83% of lithium was desorbed by treatment with a 0.5N HCl solution for 1h. A little amount (1%) of manganese was dissolved during the acid treatment. A solution containing 2,100 mg·dm-3 lithium was obtained by a multistage desorption (5 stages). The column desorption study showed that the elution curves varied depending on HCl concentration. More than 92% of the adsorbed-lithium was eluted by passing a 0.5N HCl solution with a volume of 1.5 time that of the adsorbent. The lithium concentration of the eluate reached 1,400 mg·dm-3. Alkaline earth metal ions and the other alkali metal ions in the adsorbent were also eluted to the HCl solution at nearly the same retention time as that of lithium. (author)

256

Natural Transformation of Azotobacter vinelandii by Adsorbed Chromosomal DNA: Role of Adsorbed DNA Conformation  

Science.gov (United States)

Recent increases in antibiotic resistance among pathogenic microorganisms and the accompanying public health concerns result both from the widespread use of antibiotics and from the transfer of antibiotic resistance genes among microorganisms. To understand the transfer of antibiotic resistance genes and identify efficient measures to minimize these transfers, an interdisciplinary approach was used to identify physical and chemical factors that control the fate and biological availability of extracellular DNA. Quartz crystal microbalance with dissipation (QCM-D) was used to study extracellular DNA adsorption and the conformation of the adsorbed DNA on silica and natural organic matter (NOM) surfaces. Solution chemistry was varied systematically to investigate the role of adsorbed DNA conformation on transformation. Gene transfer was assessed under the same conditions using natural transformation of chromosomal DNA into the soil bacteria Azotobacter vinelandii. DNA adsorbed to both silica and NOM surfaces has a more compact and rigid conformation in the presence of Ca2+ compared to Na+. Extracellular DNA adsorbed on silica and NOM surfaces transformed A. vinelandii. The transformation efficiency of adsorbed DNA was up to 4 orders of magnitude lower than that of dissolved DNA. Preliminary results suggest that the presence of Ca2+ in groundwater (e.g. hardness) reduces the availability of adsorbed DNA for transformation.

Lv, N.; Zilles, J.; Nguyen, H.

2008-12-01

257

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

258

Gas storage using fullerene based adsorbents  

Science.gov (United States)

This invention is directed to the synthesis of high bulk density high gas absorption capacity adsorbents for gas storage applications. Specifically, this invention is concerned with novel gas absorbents with high gravimetric and volumetric gas adsorption capacities which are made from fullerene-based materials. By pressing fullerene powder into pellet form using a conventional press, then polymerizing it by subjecting the fullerene to high temperature and high inert gas pressure, the resulting fullerene-based materials have high bulk densities and high gas adsorption capacities. By pre-chemical modification or post-polymerization activation processes, the gas adsorption capacities of the fullerene-based adsorbents can be further enhanced. These materials are suitable for low pressure gas storage applications, such as oxygen storage for home oxygen therapy uses or on-board vehicle natural gas storage. They are also suitable for storing gases and vapors such as hydrogen, nitrogen, carbon dioxide, and water vapor.

Loutfy, Raouf O. (Inventor); Lu, Xiao-Chun (Inventor); Li, Weijiong (Inventor); Mikhael, Michael G. (Inventor)

2000-01-01

259

Advances of adsorbents for hemoperfusion in China.  

Science.gov (United States)

Activated charcoal with various coating materials were screened and tested as adsorbents in hemoperfusion. Among them silicon rubber polyurethane, crosslinked agrose, polyvinyl acetate, polyhydroxy ethyl methacrylate showed good blood compatible properties. Various types of resins and carbonized resins with different functional groups, and structures were tested for the adsorption of small molecules i.e. creatinine, barbiturates, middle molecules i.e. VitB12, inulin, cytochrome C and large molecules i.e. unconjugated bilirubin. High adsorption capacities were obtained and uncoated carbonized resins showed satisfactory blood compatible properties. NK-107 a macroporous, non-coated resin is now being manufactured and successfully used clinically on patients for acute detoxification of hypnotic drugs. Polysaccharide dialdehyde and polystyrene derivatives etc. were used for the removal of urea, ammonia, potassium and phosphorus. DNA immune adsorbents were prepared for systemic lupus erythematosus therapy. PMID:2285812

Yu, Y T; Chen, C Z

1990-01-01

260

Roughening transition in adsorbed xenon multilayers  

Science.gov (United States)

Experimental evidence for a roughening transition in adsorbed xenon multilayers on palladium is presented. The clearly layer-distinctive Xe 5p photoemission is used to measure adsorption isotherms as well as the relative equilibrium population of individual Xe layers. Below a transition temperature TR xenon is adsorbed layer by layer—each layer being completed before any substantial population of the next layer occurs—with sharp first order phase transition steps for the second and third layer. Above TR the adsorption proceeds in a continuous manner, with rounded steps in the isotherms and simultaneous population of different layers. Layer population and critical temperature analysis suggests that the transition temperature is indeed the roughening temperature of the Xe film.

Miranda, R.; Albano, E. V.; Daiser, S.; Wandelt, K.; Ertl, G.

1984-03-01

261

Desorption behaviour of regular adsorbed polyampholytic layers  

OpenAIRE

The desorption behaviour of the diblock polyampholyte PMAA-b-PDMAEMA, poly(methacrylic acid)-block-poly ((dimethylamino)ethyl methacrylate), preadsorbed on silicon substrates was investigated under the influence of several desorption agents. The investigated polyampholyte is known to adsorb in regular structures directly from aqueous solutions onto silicon substrates. While the adsorption process is mainly determined by electrostatic interactions, two kinds of desorption mechanism should be a...

Mahltig, Boris; Gohy, Jean-franc?ois; Je?ro?me, Robert; Pfuetze, G.; Stamm, Manfred

2003-01-01

262

Product development studies on surface-adsorbed nanoemulsion of olmesartan medoxomil as a capsular dosage form.  

Science.gov (United States)

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

Singh, Sumita; Pathak, Kamla; Bali, Vikas

2012-12-01

263

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

264

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

265

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

266

A theoretical study of adsorbate-adsorbate interactions on Ru(0001)  

DEFF Research Database (Denmark)

Using density functional theory we study the effect of pre-adsorbed atoms on the dissociation of N(2) and the adsorption of N, N(2), and CO on Ru(0001). We have done calculations for pre-adsorbed Na, Cs, and S, and find that alkali atoms adsorbed close to a dissociating N(2) molecule will lower the barrier for dissociation, whereas S will increase it. The interaction with alkali atoms is mainly of an electrostatic nature. The poisoning by S is due to two kinds of repulsive interactions: a Pauli repulsion and a reduced covalent bond strength between the adsorbate and the surface d-electrons. In order to investigate these different interactions in more detail, we look at three different species (N atoms, and terminally bonded N(2) and CO) and use them as probes to study their interaction with two modifier atoms (Na and S). The two modifier atoms have very different properties, which allows us to decouple the different types of interactions. Adsorbed Na induces large electrostatic fields, which S does not, and Sinteracts strongly with Ru(4d) states and broadens and shifts the d band, which Na does nut do. (C) 1998 Elsevier Science B.V. All rights reserved.

Mortensen, Jens JØrgen; Hammer, BjØrk

1998-01-01

267

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)

268

Negatively Charged Ions on Mg(0001) Surfaces: Appearance and Origin of Attractive Adsorbate-Adsorbate Interactions  

Science.gov (United States)

Adsorption of electronegative elements on a metal surface usually leads to an increase in the work function and decrease in the binding energy as the adsorbate coverage rises. Using density-functional theory calculations, we show that Cl adsorbed on a Mg(0001) surface complies with these expectations, but adsorption of {N,O,F} causes a decrease in the work function and an increase in the binding energy. Analyzing the electronic structure, we show that the presence of a highly polarizable electron spill-out in front of Mg(0001) causes this unusual adsorption behavior and is responsible for the appearance of a hitherto unknown net-attractive lateral electrostatic interaction between same charged adsorbates.

Cheng, Su-Ting; Todorova, Mira; Freysoldt, Christoph; Neugebauer, Jörg

2014-09-01

269

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

270

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

271

Insights into the origin of the separation selectivity with silica hydride adsorbents.  

Science.gov (United States)

In this study, the surface properties of type-B silica have been compared with an unmodified silica hydride phase, a diamond hydride phase and silica hydride phases modified with bidentate anchored octyl (BDC8), bidentate anchored octadecyl (BDC18), phenyl and cholesteryl groups. Atomic distributions of the surface elemental composition of each type of stationary phase were determined using energy-dispersive X-ray spectroscopy. For the type-B silica, unmodified silica hydride, diamond hydride as well as BDC18 and cholesteryl silica hydride phases, the increase in carbon contents correlated with more negative surface ? potential values (R(2) = 0.92). The origin of these more negative ? potentials has been evaluated with mobile phases up to 100% (v/v) methanol content, with this property attributed to either an increase in the amount of adsorbed hydroxide ions or a decrease in the amount of adsorbed protons on the surfaces modified silica hydride phases of higher carbon content. This property of chemically modified silica hydride phases is in accordance with the unique propensity for hydroxide ions to be preferentially adsorbed onto hydrophobic surfaces of low permittivity and effects due to the specific accumulated water molecules associated with the electrical interfacial double layer of the adsorbent. PMID:25656442

Kulsing, Chadin; Nolvachai, Yada; Marriott, Philip J; Boysen, Reinhard I; Matyska, Maria T; Pesek, Joseph J; Hearn, Milton T W

2015-02-19

272

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

273

Photochemistry of small adsorbates on surfaces  

International Nuclear Information System (INIS)

This thesis is concerned with the interactions of vacuum ultraviolet photons with molecules adsorbed on surfaces and contrasts photochemistry of adsorbed systems with the photochemistry observed in gas phase molecules. Chapter 1 presents an introduction to the theoretical concepts which are relevant in the thesis. Chapter 2 details the experimental apparatus used to obtain data, and describes the procedures taken during data acquisition. Chapter 3 presents results from a photon stimulated desorption (PSD) experiment on the O2/graphite system. The yield of positive and negative atomic oxygen ions are presented as a function of photon energy and coverage and is found to be similar to the gas-phase ion production, but with extra photo electron-driven channels for negative ion production. Chapter 4 describes two experiments performed on the CH3Cl/graphite system. The first uses electron energy loss spectroscopy EELS to measure the rate of dissociation of CH3Cl under irradiation of the EELS beam. The other is a PSD study which records the yield of H+ and CH3+ ions as a function of photon energy and coverage. The results are found to agree with previously published structural studies of the system. Chapter 5 presents PSD results from three further systems. In C2H4/graphite, only H+ ions are detected. In the NO/graphite system, only a weak signal of NO+ was detected.eak signal of NO+ was detected. Finally, in the CO2/graphite, O2+ and CO+ were detected. Two-stage processes are proposed involving reactions between adsorbates are proposed to explain the appearance of these ions. Chapter 6 is a preliminary study of X-ray induced dissociation within self-assembled monolayers which uses X-ray photoelectron spectroscopy (XPS). Chapter 7 provides some conclusions which can be drawn from this work, and offers suggestions for future work. (author)

274

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

275

Theory for melting anomalies in adsorbate systems  

International Nuclear Information System (INIS)

Melting anomalies, observed in a variety of adsorbate systems such as N2, Ar or CH4 on TiO2 and H2O absorbed in coal, Al2O3, zeolite, or porous glass, are shown to be manifestations of the melting characteristics of small molecular clusters. The theoretical results show not only that melting is a continuous phenomenon for small aggregates, but that for clusters consisting of ten to twenty molecules, melting may commence at temperatures considerably lower than the bulk melting point. Comparison between the theory and experimental data yields excellent agreement. (orig.)

276

Switching photochromic molecules adsorbed on optical microfibres.  

Science.gov (United States)

The internal state of organic photochromic spiropyran molecules adsorbed on optical microfibres is optically controlled and measured by state-dependent light absorption. Repeated switching between the states is achieved by exposure to the evanescent field of a few nanowatts of light guided in the microfibre. By adjusting the microfibre evanescent field strength the dynamic equilibrium state of the molecules is controlled. Time-resolved photoswitching dynamics are measured and modelled with a rate equation model. We also study how many times the photochromic system can be switched before undergoing significant photochemical degradation. PMID:22714300

Wiedemann, U; Alt, W; Meschede, D

2012-06-01

277

?-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)

278

Conformational Properties of an Adsorbed Charged Polymer  

CERN Document Server

The behavior of a strongly charged polymer adsorbed on an oppositely charged surface of low-dielectric constant is formulated by the functional integral method. By separating the translational, conformational, and fluctuational degrees of freedom, the scaling behaviors for both the height of the polymer and the thickness of the diffusion layer are determined. Unlike the results predicted by scaling theory, we identified the continuous crossover from the weak compression to the compression regime. All teh analytical results are found to be consistent with Monte-Carlo simulations. Finally, an alternative (operational) definition of a charged polymer adsorption is proposed.

Cheng, C H; Cheng, Chi-Ho; Lai, Pik-Yin

2004-01-01

279

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

280

Application of bifunctional magnetic adsorbent to adsorb metal cations and anionic dyes in aqueous solution  

International Nuclear Information System (INIS)

A magnetic adsorbent, amine-functionalized silica magnetite (NH2/SiO2/Fe3O4), has been synthesized to behave as an anionic or cationic adsorbent by adjusting the pH value of the aqueous solution to make amino groups protonic or neutral. NH2/SiO2/Fe3O4 were used to adsorb copper ions (metal cation) and Reactive Black 5 (RB5, anionic dye) in an aqueous solution in a batch system, and the maximum adsorption were found to occur at pH 5.5 and 3.0, respectively. The adsorption equilibrium data were all fitted the Langmuir isotherm equation reasonably well, with a maximum adsorption capacity of 10.41 mg g-1 for copper ions and of 217 mg g-1 for RB5. A pseudo-second-order model also could best describe the adsorption kinetics, and the derived activation energy for copper ions and RB5 were 26.92 kJ mol-1 and 12.06 kJ mol-1, respectively. The optimum conditions to desorb cationic and anionic adsorbates from NH2/SiO2/Fe3O4 were provided by a solution with 0.1 M HNO3 for copper ions and with 0.05 M NaOH for RB5.

281

Structured fixed-bed adsorber based on zeolite/sintered metal fibre for low concentration VOC removal  

OpenAIRE

A novel adsorber with a structured fixed-bed made of sintered metal fibres (SMF) plates has been developed for purification of low-content VOCs gas-streams. The surface of the metal fibres was coated by a thin, homogeneous MFI-type (ZSM-5, Silicalite-1) zeolite film. The zeolite/SMF composite has been shown as an efficient adsorbent, in which VOCs in low content streams are first concentrated and desorbed in a second step with higher concentrations suitable for oxidation. The advantages of th...

Nikolajsen, K.; Kiwi-minsker, L.; Renken, A.

2006-01-01

282

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)

283

An efficient molecular docking method for adsorbent screening.  

Science.gov (United States)

In this study, with flavonol glycosides (FG) and terpene lactones (TL) in ginkgo biloba extract (GBE) as the targets for separation, we investigated the effectiveness of molecular docking in adsorbent screening. Several polyamine-modified methyl acylate-co-divinylbenzene (MA-co-DVB) adsorbent models were built, and their affinity to rutin, quercetin and ginkgolide B (GB) was evaluated via molecular docking. The model of ethylenediamine-modified adsorbent showed the largest difference in affinity between to GB and to quercetin as well as rutin, and thus this adsorbent could have the best separation performance. The results of the subsequently conducted static adsorption and dynamic adsorption experiments correlated well with docking results. Finally, using ethylenediamine-modified MA-co-DVB adsorbent, nearly complete separation of the FG and TL in GBE was simply achieved by one step of adsorption-desorption. Thus, the reported molecular docking method is expected to be helpful for rapid adsorbent screening. PMID:21514905

Wang, Jun; Zhang, Saihui; Zhang, Jing; Ren, Ping; Chen, Yingchao; Li, Jihong; Wang, Wei; Ma, Yi; Shi, Rongfu; Wang, Chunhong; Yuan, Zhi

2011-06-01

284

Fibrous metal ion adsorbent synthesized by radiation processing  

International Nuclear Information System (INIS)

Graft polymerization is a radiation processing which can impart a desired functional group into a trunk polymer. When a nonwoven fabric is selected as the trunk polymer of the graft polymerization, a fibrous metal adsorbent can be synthesized. The resulting fibrous adsorbent realizes extremely high flow rate in the metal ion adsorption. The present paper describes the characteristic of the fibrous adsorbent and the applications to removal of toxic metals and collection of useful metals. (author)

285

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

286

Adsorption of ?-galactosidase on silica and aluminosilicate adsorbents  

Science.gov (United States)

It is shown that adsorption of ?-galactosidase of Aspergillus oryzae fungi on mesoporous and biporous silica and aluminosilicate adsorbents and the rate of the process grow along with the diameter of the pores of the adsorbent. It is found that the shape of the adsorption isotherms changes as well, depending on the texture of the adsorbent: the Michaelis constant rises from 0.3 mM for the enzyme in solution to 0.4-0.5 mM for the enzyme on a surface in the hydrolysis of o-nitrophenyl-?-D-galactopyranoside. It is concluded that ?-galactosidase displays its maximum activity on the surface of biporous adsorbents.

Atyaksheva, L. F.; Dobryakova, I. V.; Pilipenko, O. S.

2015-03-01

287

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)

288

Durability of CMPO impregnated silica adsorbent under irradiation conditions  

International Nuclear Information System (INIS)

Separation of Cs and Sr from simulated high-level radioactive liquid waste (HLLW) was performed using an octylphenyl-N,N-diisobutylcarbomoyl phosphine oxide impregnated silica adsorbent (CMPO-adsorbent). As part of HLLW treatment, the adsorbent is subjected to strong irradiation. Therefore, the durability of CMPO-adsorbent under gamma-ray irradiation conditions was studied. CMPO decomposed to phosphoric acid after a transition to octylphenyl phosphinic acid (OPP). The adsorbed amount of actinoids and lanthanoids were found to decrease linearly with increasing irradiation dose. However, at a dose of 2 MGy, the CMPO-adsorbent was able to maintain adsorption at a rate of 80% of its initial capacity. Based on this finding, it is estimated that the adsorbent can be used in the treatment of HLLW for 400-500 cycles. Radiolytic degradation products increase with increasing irradiation dose caused by HLLW. If OPP accumulates in a CMPO-adsorbent, actinoids and lanthanoids are not recovered. OPP dissolves easily by washing with an eluent, suggesting that OPP would not accumulate in the adsorbent. After washing, separation performance was maintained with a dose of 2 MGy. (author)

289

Collective Motion and Structural Order in Adsorbate Vibrational Dynamics  

International Nuclear Information System (INIS)

A simple, broadly applicable theory is developed to describe resonant vibrational coupling between adsorbates and a substrate lattice. This is one of the principal mechanisms governing the relaxation of adsorbate vibrations. This theory can be applied to widely varying surface coverages and arbitrary overlayer structures, and it correctly incorporates collective adsorbate motion, which has been shown to have a critical impact on the relaxation dynamics. Vibrational lifetimes predicted by this theory are in excellent quantitative agreement with experiments on adsorbate systems ranging from a diffuse, disordered overlayer to a dense, periodic overlayer. copyright 1998 The American Physical Society

290

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

291

Understanding Trends in Catalytic Activity: The Effect of Adsorbate-Adsorbate Interactions for CO Oxidation Over Transition Metals  

DEFF Research Database (Denmark)

Using high temperature CO oxidation as the example, trends in the reactivity of transition metals are discussed on the basis of density functional theory (DFT) calculations. Volcano type relations between the catalytic rate and adsorption energies of important intermediates are introduced and the effect of adsorbate-adsorbate interaction on the trends is discussed. We find that adsorbate-adsorbate interactions significantly increase the activity of strong binding metals (left side of the volcano) but the interactions do not change the relative activity of different metals and have a very small influence on the position of the top of the volcano, that is, on which metal is the best catalyst.

Grabow, Lars; Larsen, Britt Hvolbæk

2010-01-01

292

Elution of radium adsorbed by microbial biomass  

Energy Technology Data Exchange (ETDEWEB)

The present work examines the equilibrium and kinetics of the elution of radium-226 adsorbed by inactive (dead) microbial biomass. Two biomass types, P. chrysogenum and activated sludge, were examined. Values were determined for engineering design parameters such as eluant type, eluant concentration and solid to liquid ratio. Five eluants (EDTA, NTAA, TAC, HCl, HNO/sub 3/) were selected and studied. The mineral acids and EDTA were shown to be the most efficient radium eluants. The radium readsorption potential of the biomass following elution was also examined and shown to be severely limited, especially when mineral acids were used as eluants. The rate of radium desorption from the biomass, using mineral acids, is shown to be very rapid, with complete elution accomplished within one or two minutes.

Tsezos, M.; Baird, M.H.I.; Shemilt, L.W.

1987-03-15

293

Canyon solvent cleaning with solid adsorbents  

International Nuclear Information System (INIS)

The HM Process at the Savannah River Plant (SRP) uses 7.5% tributyl phosphate in n-paraffin as an extraction solvent. During use, the solvent is altered due to hydrolysis and radiolysis, forming materials that influence product losses, product decontamination, and separation efficiencies. Laboratory studies to improve online solvent cleaning have shown that carbonate washing, although removing residual solvent activity, does not remove binding ligands that hold fission products in the solvent. Treatment of solvent with a solid adsorbent removes binding ligands and significantly improves recycle solvent performance. Both laboratory work defining a full-scale adsorption process and the use of the process to clean HM Process first cycle solvent are presented

294

In vitro hydroxyapatite adsorbed salivary proteins  

International Nuclear Information System (INIS)

In spite of the present knowledge about saliva components and their respective functions, the mechanism(s) of pellicle and dental plaque formation have hitherto remained obscure. This has prompted recent efforts on in vitro studies using hydroxyapatite (HA) as an enamel model. In the present study salivary proteins adsorbed to HA were extracted with TFA and EDTA and resolved by 2D electrophoresis over a pH range between 3 and 10, digested, and then analysed by MALDI-TOF/TOF mass spectrometry and tandem mass spectrometry. Nineteen different proteins were identified using automated MS and MS/MS data acquisition. Among them, cystatins, amylase, carbonic anhydrase, and calgranulin B, were identified

295

Quantum surface diffusion of interacting adsorbates  

CERN Document Server

A quantum atom-surface diffusion model with interacting adsorbates is proposed to the intermediate scattering function. Within this model, the intermediate scattering function is shown to be complex-valued and factorizable into a classical-like and a quantum-mechanical part. Applications to the diffusion of Na atoms on flat and corrugated Cu(001) surfaces at different coverages and surface temperatures are analyzed. As shown, quantum effects are relevant to diffusion at low surface temperatures and coverages even for relatively heavy particles, such as Na atoms. Below 100 K, the corresponding calculations are particularly appropriate to also obtain jump mechanisms and peak positions of the low-frequency frustrated translational modes and friction coefficients, commonly extracted from extrapolation to zero temperature.

Martinez-Casado, R; Miret-Artés, S

2008-01-01

296

Limited Range Fractality of Randomly Adsorbed Rods  

CERN Document Server

Multiple resolution analysis of two dimensional structures composed of randomly adsorbed penetrable rods, for densities below the percolation threshold, has been carried out using box-counting functions. It is found that at relevant resolutions, for box-sizes, $r$, between cutoffs given by the average rod length $$ and the average inter-rod distance $r_1$, these systems exhibit apparent fractal behavior. It is shown that unlike the case of randomly distributed isotropic objects, the upper cutoff $r_1$ is not only a function of the coverage but also depends on the excluded volume, averaged over the orientational distribution. Moreover, the apparent fractal dimension also depends on the orientational distributions of the rods and decreases as it becomes more anisotropic. For box sizes smaller than $$ the box counting function is determined by the internal structure of the rods, whether simple or itself fractal. Two examples are considered - one of regular rods of one dimensional structure and rods which are tri...

Lidar, D A; Avnir, D; Lidar, Daniel A.; Biham, Ofer; Avnir, David

1997-01-01

297

Effects of cathode current density on structure and corrosion resistance of plasma electrolytic oxidation coatings formed on ZK60 Mg alloy  

Energy Technology Data Exchange (ETDEWEB)

Current density is a key factor in plasma electrolytic oxidation (PEO) process. The aim of this paper is to study the effects of cathode current density on the composition, morphology, and corrosion resistance of ceramic coatings on ZK60 magnesium alloy prepared through bi-polar plasma electrolytic oxidation in Na{sub 3}PO{sub 4} solution. The phase composition, morphology, and corrosion resistance were studied by X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Electrochemical Impedance Spectroscopy (EIS) and potentiodynamic polarization in 3.5% NaCl solution. It is found that the as-produced coatings are only composed of MgO. The increase of cathode current density made the coatings less porous and more compact. Analysis of EIS and potentiodynamic polarization technique on the samples shows that the corrosion resistance of the coated samples is better than that of ZK60 magnesium alloy, and that a bigger cathode current density can improve the corrosion resistance of as-prepared coatings.

Su Peibo [School of Chemistry Technology, Harbin Institute of Technology, Harbin 150001 (China); Wu Xiaohong [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China); National Key Laboratory of Vacuum and Cryogenics Technology and Physics, Lanzhou Institute of Physics, Lanzhou 730000 (China); Guo Yun [National Key Laboratory of Vacuum and Cryogenics Technology and Physics, Lanzhou Institute of Physics, Lanzhou 730000 (China); Jiang Zhaohua [School of Chemistry Technology, Harbin Institute of Technology, Harbin 150001 (China)], E-mail: supeibo@yahoo.com.cn

2009-05-05

298

Effects of cathode current density on structure and corrosion resistance of plasma electrolytic oxidation coatings formed on ZK60 Mg alloy  

International Nuclear Information System (INIS)

Current density is a key factor in plasma electrolytic oxidation (PEO) process. The aim of this paper is to study the effects of cathode current density on the composition, morphology, and corrosion resistance of ceramic coatings on ZK60 magnesium alloy prepared through bi-polar plasma electrolytic oxidation in Na3PO4 solution. The phase composition, morphology, and corrosion resistance were studied by X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Electrochemical Impedance Spectroscopy (EIS) and potentiodynamic polarization in 3.5% NaCl solution. It is found that the as-produced coatings are only composed of MgO. The increase of cathode current density made the coatings less porous and more compact. Analysis of EIS and potentiodynamic polarization technique on the samples shows that the corrosion resistance of the coated samples is better than that of ZK60 magnesium alloy, and that a bigger cathode current density can improve the corrosion resistance of as-prepared coatings.

299

A comprehensive study on electrochemical performance of Mn-surface-modified LiNi0.8Co0.15Al0.05O2 synthesized by an in situ oxidizing-coating method  

Science.gov (United States)

The degradation of Ni-rich LiNi0.8Co0.15Al0.05O2 cathode material is successfully suppressed via a facile in situ oxidizing-coating method. KMnO4 is used as not only a Mn source but also an oxidant. X-ray diffraction (XRD) and scanning electron microscope (SEM) results demonstrate that the structure and morphology of the KMnO4-pretreated sample are the same as the pristine one. X-ray photoelectron spectroscopy (XPS) confirms that the valence state of Mn is +4 and the Ni3+ ions are partly reduced to Ni2+ when the material is doped with Mn4+. Besides, the Mn4+ ions are proved to distribute uniformly on the surface of the materials particles through energy dispersive spectrometer (EDS) and EDS elemental mapping. And it is confirmed that the concentration of Ni in the outer layer is reduced by the Mn-surface-modification. From the electrochemical characterizations, it is confirmed that the presence of tetravalent Mn at the surface can suppress the capacity fading during charge-discharge cycles, even under elevated temperature and overcharge conditions, and can prevent the material from deterioration during storage in air.

Huang, Bin; Li, Xinhai; Wang, Zhixing; Guo, Huajun; Shen, Li; Wang, Jiexi

2014-04-01

300

The morphology, proliferation rate, and population doubling time factor of adipose-derived mesenchymal stem cells cultured on to non-aqueous SiO2, TiO2, and hybrid sol-gel-derived oxide coatings.  

Science.gov (United States)

In recent years, much attention has been paid to the development of tissue engineering and regenerative medicine, especially when stem cells of various sources are concerned. In addition to the interest in mesenchymal stem cells isolated from bone marrow, recently more consideration has been given to stem cells isolated from adipose tissue (AdMSCs), due to their less invasive method of collection as well as their ease of isolation and culture. However, the development of regenerative medicine requires both the application of biocompatible material and the stem cells to accelerate the regeneration. In this study, we investigated the morphology, proliferation rate index (PRi), and population doubling time factor of adipose-derived mesenchymal stem cells cultured on non-aqueous sol-gel-derived SiO2, TiO2, and SiO2/TiO2 oxide coatings. The results indicated an increase in PRi of AdMSCs when cultured on to titanium dioxide, suggesting its high attractiveness for AdMSCs. In addition, the proper morphology and the shortest doubling time of AdMSCs were observed when cultured on titanium dioxide coating. PMID:24408867

Marycz, Krzysztof; Krzak-Ro?, Justyna; Donesz-Sikorska, Anna; ?mieszek, Agnieszka

2014-11-01

301

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

302

Development of a simplified separation process of trivalent minor actinides from fission products using novel R-BTP/SiO2-P adsorbents  

International Nuclear Information System (INIS)

From a viewpoint of direct separation of trivalent minor actinides (MA: Am, Cm etc.) from fission products (FP) including rare earths (RE) in high level radioactive liquid waste, the authors have developed a simplified separation process using a single column packed with novel extraction adsorbents. Attention was paid to a new type of nitrogen-donor ligand, R-BTP (2,6-bis(5,6-dialkyl-1,2,4-triazin-3-yl)pyridine, R: alkyl group) as an extractant because it has higher extraction selectivity for Am(III) than RE(III). Since the R-BTP ligands show different properties such as adsorbability and stability when they have different alkyl groups, several R-BTP extraction adsorbents were prepared by impregnating the R-BTP ligands with different alkyl groups (isohexyl-, isoheptyl- and cyheptyl-BTP) into a porous silica/polymer composite support (SiO2-P particles). This work investigated: (1) fundamental properties of the synthesized R-BTP/SiO2-P adsorbents, (2) adsorption and desorption properties of Am and FP in nitric acid solution and water using the adsorbents in a batch experiment, (3) radiolytic and chemical stabilities of the adsorbents, and (4) the possibility for developing a simplified separation process of MA using the most promising adsorbent (isohexyl-BTP/SiO2-P) under temperature control between 25 and 50degC. (author)

303

Experimental Evidence of a Roughening Transition in Adsorbed Xenon Multilayers  

Science.gov (United States)

In this Letter evidence is provided for a roughening transition in adsorbed xenon multilayers on palladium. The layer-distinctive Xe 5p photoemission is used to measure adsorption isotherms as well as the relative equilibrium population of individual Xe layers. Below the roughening temperature TR xenon adsorbs layer by layer. Above TR simultaneous population of different layers takes place.

Miranda, R.; Albano, E. V.; Daiser, S.; Ertl, G.; Wandelt, K.

1983-08-01

304

SORPTION PROPERTIES OF MODEL COMPOUNDS ON C18 ADSORBENTS  

Science.gov (United States)

The bonded silica adsorbent Bondapak-C18 was evaluated for removing organic matter from secondary sewage effluents and from solutions of pure organic compounds. The adsorbent is hydrophobic and its behavior with water samples may be erratic unless first wet with a solvent. Howeve...

305

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%

306

Adsorbate vibrational mode enhancement of radiative heat transfer  

OpenAIRE

We show that the radiative heat transfer between two solid surfaces at short separation may increase by many order of magnitude when the surfaces are covered by adsorbates. In this case the heat transfer is determined by resonant photon tunneling between adsorbate vibrational modes. We propose an experiment to check the theory.

Volokitin, A. I.; Persson, B. N. J.

2006-01-01

307

Composite 5A zeolite with ultrathin porous TiO2 coating for selective gas adsorption.  

Science.gov (United States)

A composite zeolite adsorbent was prepared by conformally depositing an ultrathin porous TiO2 coating on the external surface of the 5A zeolite by molecular layer deposition (MLD) and subsequent calcination. The composite adsorbent showed significantly improved ideal adsorption selectivity for CO2-CH4, CO2-N2 and propylene-propane. PMID:25406720

Song, Zhuonan; Huang, Yi; Wang, Lei; Li, Shiguang; Yu, Miao

2015-01-01

308

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

309

The effect of NaOH concentration on the steam-hydrothermally treated bioactive microarc oxidation coatings containing Ca, P, Si and Na on pure Ti surface.  

Science.gov (United States)

The microarc oxidation (MAO) coating covered pure Ti plates are steam-hydrothermally treated in autoclaves containing NaOH solutions with different concentrations of 0, 0.001, 0.01, 0.1 and 1mol·L(-1). Due to the composition of Ti, O, Ca, P, Si and Na elements in the MAO coating, anatase and hydroxyapatite (HA) crystals are generated from the previously amorphous MAO coating after the steam-hydrothermal treatment. Meanwhile, it is noticed that the amount of HA crystals increases but showing a decline trend in aspect ratio in morphologies with the increasing of NaOH concentration. Interestingly, the steam-hydrothermally treated MAO coatings exhibit better bonding strength with Ti substrate (up to 43.8±1.1MPa) than that of the untreated one (20.1±3.1MPa). In addition, benefiting from the corrosive attack of the dissolved NaOH in water vapor on the MAO coating, Ti-OH is also formed on the steam-hydrothermally treated MAO coating surface, which can trigger apatite nucleation. Thus, the steam-hydrothermally treated MAO coatings exhibit good apatite-inducing ability. PMID:25686996

Zhou, Rui; Wei, Daqing; Cao, Jianyun; Feng, Wei; Cheng, Su; Du, Qing; Li, Baoqiang; Wang, Yaming; Jia, Dechang; Zhou, Yu

2015-04-01

310

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

311

Photoluminescence and electrical properties of highly transparent (Bi,Eu)4Ti3O12 ferroelectric thin films on indium-tin-oxide-coated glass substrates  

Science.gov (United States)

Highly transparent (Bi,Eu)4Ti3O12 (BEuT) ferroelectric thin films were prepared on indium-tin-oxide (ITO)-coated glass substrates by using chemical solution deposition technique, and the photoluminescence and electrical properties of the thin films were investigated in terms of annealing temperature and concentration of europium ions. The BEuT thin films had a polycrystalline bismuth-layered perovskite structure and exhibited excellent optical transmittance. Photoluminescence spectra of the thin films included two strong peaks which originated from two transitions of D05?F17 (594nm) and D05?F27 (617nm). The emission intensity of two peaks increases with increasing annealing temperature due to improved crystallinity of the thin films. An unusual composition quenching effect of photoluminescence was found in the rare earth doped bismuth titanate thin films. In addition, the BEuT thin films also showed ferroelectric properties comparable to those of BEuT thin films deposited on Pt /Ti/SiO2/Si substrates. These results suggest that BEuT thin films can be considered as a promising multifunctional material which can find applications in transparent optoelectronic devices.

Ruan, Kaibin; Chen, Xinman; Liang, Tong; Wu, Guangheng; Bao, Dinghua

2008-04-01

312

Modulation Effects of K2ZrF6 Additive on Microstructure and Heat Resistance of Micro-arc Oxide Coatings Fabricated on LY12 Aluminum Alloy  

Directory of Open Access Journals (Sweden)

Full Text Available Zr(OH4 particle can be formed and negatively charged in alkaline solution with K2ZrF6 addition. Based on this mechanism, Zr-containing ceramic coatings were fabricated on LY12 aluminum alloy by microarc oxidation (MAO using K2ZrF6 as a special additive in Na2SiO3-KOH base electrolyte. The modulation effects of K2ZrF6 addition on micro-microstructure, element distribution and phase composition were analyzed by SEM, EDS and XRD, respectively. Heat resistance of MAO coatings formed on LY12 aluminum alloy in different electrolyte was investigated. The results show that the K2ZrF6 addition can increase the micro-arc oxidation rate and significantly alter the structure of MAO coatings. Both the top surface and inner surface of MAO coatings fabricated in Zr-containing electrolyte become relatively smooth. Compared with the coating formed in Zr-free electrolyte, a large amount of Zr element is found in the coating formed in electrolyte with K2ZrF6 addition. Two main phases, ?-Al2O3 and ?-Al2O3, are contained in Zr-free coating. In contrast, more amorphous phase is found in Zr-containing coating with reduced amount of crystalline alumina. Experimental results also demonstrate that Zr-containing coating exhibits higher heat resistance.

ZHANG Xin-Meng, CHEN Dong-Fang, GONG Chun-Zhi , YANG Shi-Qin, TIAN Xiu-Bo

2010-07-01

313

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

314

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

315

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.

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

2013-05-01

316

Effect of (NaPO3)6 concentrations on corrosion resistance of plasma electrolytic oxidation coatings formed on AZ91D magnesium alloy  

International Nuclear Information System (INIS)

Different plasma electrolytic oxidation (PEO) coatings were prepared on AZ91D magnesium alloy in electrolytes containing various concentrations of (NaPO3)6. The morphologies, chemical compositions and corrosion resistance of the PEO coatings were characterized by environmental scanning electron microscopy (ESEM), X-ray diffractometer (XRD), energy dispersive analysis of X-rays (EDAX), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) test. The results showed that the PEO coatings were mainly composed of MgO, Mg2SiO4, MgAl2O4 and amorphous compounds. As the (NaPO3)6 concentrations increased from 0 to 10 g/l, the thickness and surface roughness of the coatings approximately linearly increased; the MgO and Mg2SiO4 phase increased within the concentration range of 0-3 and 0-5 g/l, and then decreased within the range of 3-10 and 5-10 g/l, respectively, while the MgAl2O4 phase gradually decreased. Moreover, the corrosion resistance of the coatings increased within the range of 0-5 g/l and then decreased within the range of 5-10 g/l. The best corrosion resistance coating was obtained in electrolyte containing 5 g/l (NaPO3)6, it had the most compact microstructure. Besides, a reasonable equivalent circuit was established, and the fitting results were consistent with the results of the EIS teststent with the results of the EIS test

317

Fracture resistance of a TiB2 particle/SiC matrix composite at elevated temperature  

Science.gov (United States)

The fracture resistance of a commercial TiB2 particle/SiC matrix composite was evaluated at temperatures ranging from 20 to 1400 C. A laser interferometric strain gauge (LiSG) was used to continuously monitor the crack mouth opening displacement (CMOD) of the chevron-notched and straight-notched, three-point bend specimens used. Crack growth resistance curves (R-curves) were determined from the load versus displacement curves and displacement calibrations. Fracture toughness, work-of-fracture, and R-curve levels were found to decrease with increasing temperature. Microstructure, fracture surface, and oxidation coat were examined to explain the fracture behavior.

Jenkins, Michael G.; Salem, Jonathan A.; Seshadri, Srinivasa G.

1989-01-01

318

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

319

The structure of adsorbed cyclic chains.  

Science.gov (United States)

In order to determine the structure of polymer films formed of cyclic chains (rings) we developed and studied a simple coarse-grained model. Our main goal was to check how the percolation and jamming thresholds in such a system were related to the thresholds obtained for linear flexible chains system, i.e., how the geometry of objects influenced both thresholds. All atomic details were suppressed and polymers were represented as a sequence of identical beads and the chains were embedded to a square lattice (a strictly 2D model). The system was athermal and the excluded volume was the only potential introduced. A random sequential adsorption algorithm was chosen to determine the properties of a polymer monolayer. It was shown that the percolation threshold of cyclic chains was considerably higher than those of linear flexible chains while the jamming thresholds for both chain architectures are very similar. The shape of adsorbed cyclic chains was found to be more prolate when compared to average single chain. PMID:25701088

Kuriata, Aleksander; Sikorski, Andrzej

2015-03-01

320

Surface characterization of Ag/Titania adsorbents  

International Nuclear Information System (INIS)

The Ag/Titania adsorbent for selective removal of the desulfurization-refractive polycyclic aromatic sulfur heterocycles (PASHs) from liquid hydrocarbon fuels was prepared, its total and the Ag specific surface area were determined and the surface reaction sites in the sorbent that may be active in the adsorptive selective desulfurization were characterized by several spectroscopic and surface science techniques. The sorbent contains Ag, Ti, O and spurious C on its surface, as by the XPS measurements. Silver is present as an oxide, as judged by the XPS Auger parameter (AP). The complementary electron spin resonance (ESR) spectroscopy confirms that the majority of Ag is present in the diamagnetic Ag1+ form, with the minor concentration (?0.1% of total Ag) present as Ag2+. The findings by XPS and ESR are confirmed by the XRD, UV-vis spectroscopy and thermodynamic considerations. The supported Ag is highly dispersed on the surface of the titania support, with the particle size of ?30-60 A depending on Ag content, with an Ag specific surface area of ?7-14 m2/g, vs. the total surface area of ?114-58 m2/g.

321

Mixing behaviour in 2D layers of linear alkanes adsorbed on graphite  

Science.gov (United States)

Solid monolayers of binary mixtures of linear alkanes adsorbed on graphite are investigated at 10 K by X-ray diffraction. Monolayers of n-heptane and n-nonane, which belong to the same 2D space group, mix continuously over the whole range of composition. In contrast, n-nonane and n-decane belonging to different space groups have only limited miscibility. Interestingly, the isomorphous monolayers of n-octane and n-decane form a molecular compound. Such variety of the mixing behaviour is substantially different from that observed for the solid monolayers formed at the liquid-graphite interface.

Inaba, Akira; Clarke, Stuart M.; Arnold, Thomas; Thomas, Robert K.

2002-01-01

322

Hollow mesoporous carbon spheres with magnetic cores and their performance as separable bilirubin adsorbents.  

Science.gov (United States)

Hollow mesoporous carbon spheres with magnetic cores are directly replicated from hollow mesoporous aluminosilicate spheres with hematite cores by a simple incipient-wetness impregnation technique. The amount of magnetic cores and the saturation magnetization value can be easily tuned by changing the concentration of iron nitrate solution used in the synthesis procedure. As-prepared hollow mesoporous carbon spheres with magnetic cores are used as separable bilirubin adsorbents and show very good adsorptive properties. The characteristics of as-prepared composites are examined by XRD, N(2) sorption, TEM, vibrating-sample magnetometry, and UV/Vis spectroscopy. PMID:19582733

Guo, Limin; Cui, Xiangzhi; Li, Yongsheng; He, Qianjun; Zhang, Lingxia; Bu, Wenbo; Shi, Jianlin

2009-09-01

323

Directed path models of adsorbing and pulled copolymers  

International Nuclear Information System (INIS)

In this paper we examine the phases of a directed path model of a copolymer attached to a surface under the influence of a pulling force. The simplest model of an adsorbing directed polymer, attached at the one end to a surface and pulled from the surface by the other end, is reviewed—its phase diagram includes free, adsorbed and ballistic phases. In contrast to this model, we consider an adsorbing directed block copolymer attached at both endpoints to the adsorbing surface, and pulled away from the surface at its middle vertex. The phase diagram of this model includes ballistic, adsorbed and free phases, as well as a quasi-ballistic phase which has characteristics of both an adsorbed and a ballistic phase. We also generalize our methods to a model of directed block star copolymers and show that such directed copolymers have numerous adsorbed and quasi-ballistic phases. The phase transitions in this system are continuous in some cases and first order in others

324

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

325

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

326

Investigation of polymer brushes and adsorbed layers under shear  

International Nuclear Information System (INIS)

Neutron reflectometry was used to investigate the density profiles of polymer brushes and an adsorbed polymer layer under shear. The brushes consisted of end-functionalized deuterated polystyrene. The adsorbed polymer was a random copolymer of deuterated styrene and 4-vinylpyridine. The brush and the adsorbed layer were sheared by the flowing of solvents over the polymer, with a maximum shear rate of 104s-1. Density profiles of the brush and the layer were determined before, during and after shear. The shear had no observable effect on the polymer profiles in any of the experiments. We discuss these results in the context of other experiments and a recent theory. (orig.)

327

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

328

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

329

Removal of adsorbed gases with CO2 snow  

Science.gov (United States)

During the outgassing of orbiting astronomical observatories, the condensation of molecular species on optical surfaces can create difficulties for astronomers. The problem is particularly severe in ultraviolet astronomy where the adsorption of only a few atomic layers of some substances can be very damaging. In this paper the removal of adsorbed atomic layers using carbon dioxide snow is discussed. The rate of removal of adsorbed layers of isopropyl alcohol, Freon TF, and deionized distilled water on Teflon substrates was experimentally determined. The removal of fingerprints (containing fatty acids such as stearic acid) from optical surfaces is also demonstrated. The presence and rate of removal of the multilayers was monitored by detecting the molecular dipole field of adsorbed molecular species. For isopropyl alcohol, Freon TF (trichlorotrifluoroethane), and water adsorbed multilayers were removed in under 1.5 seconds. Fingerprint removal was much more difficult and required 20 seconds of spraying with a mixture of carbon dioxide snow flakes and atomized microdroplets of isopropyl alcohol.

Zito, Richard R.

1991-09-01

330

Electronic structure of benzene adsorbed on Ni and Cu surfaces  

Energy Technology Data Exchange (ETDEWEB)

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 {pi} 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.

Weinelt, M.; Nilsson, A.; Wassdahl, N. [Uppsala Univ. (Sweden)] [and others

1997-04-01

331

Development of novel adsorbents for environmental cleaning by radiation  

International Nuclear Information System (INIS)

In order to improve our amenity spaces, the demand of non-odorous atmosphere is needed. Toxic gases such as trimethylamine and ammonia have been treated as the pollutant of the atmosphere. The development of an excellent and effective adsorbent for the toxic gases has been performed here and there all over the world. However, the development of the adsorbent with the consideration for conservation of environment must be made as one of the requisites. Therefore, we proposed the use of radiation for the preparation of toxic-gas-adsorbing materials. On the other hand, in our daily life, the large amount of calcium and magnesium contained in our drinking water has hindered the removal of a trace amount of pollutant such as lead. As a result, the development of the metal-ion-adsorbing material is very indispensable indeed. (J.P.N.)

332

TESTING OF CARBONACEOUS ADSORBENTS FOR REMOVAL OF POLLUTANTS FROM WATER  

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Full Text Available Testing of carbonaceous adsorbents for removal of pollutants from water. Relevant direction for improving of quality of potable water is application of active carbons at various stages of water treatments. This work includes complex research dealing with testing of a broad spectrum of carbonaceous adsorbents for removal of hydrogen sulfide and nitrite ions from water. The role of the surface functional groups of carbonaceous adsorbents, their acid-basic properties, and the influence of the type of impregnated heteroatom (N, O, or metals (Fe, Cu, Ni, on removal of hydrogen sulfide species and nitrite ions have been researched. The efficiency of the catalyst obtained from peach stones by impregnation with Cu2+ ions of oxidized active carbon was established, being recommended for practical purposes to remove the hydrogen sulfide species from the sulfurous ground waters. Comparative analysis of carbonaceous adsorbents reveals the importance of surface chemistry for oxidation of nitrite ions.

RAISA NASTAS

2012-03-01

333

Atomic scale friction of molecular adsorbates during diffusion  

CERN Document Server

Experimental observations suggest that molecular adsorbates exhibit a larger friction coefficient than atomic species of comparable mass, yet the origin of this increased friction is not well understood. We present a study of the microscopic origins of friction experienced by molecular adsorbates during surface diffusion. Helium spin-echo measurements of a range of five-membered aromatic molecules, cyclopentadienyl (Cp), pyrrole and thiophene, on a copper(111) surface are compared with molecular dynamics simulations of the respective systems. The adsorbates have different chemical interactions with the surface and differ in bonding geometry, yet the measurements show that the friction is greater than 2 ps$^{-1}$ for all these molecules. We demonstrate that the internal and external degrees of freedom of these adsorbate species are a key factor in the underlying microscopic processes and identify the rotation modes as the ones contributing most to the total measured friction coefficient.

Lechner, B A J; Hedgeland, H; Jardine, A P; Hinch, B J; Allison, W; Ellis, J

2013-01-01

334

Oil palm biomass as an adsorbent for heavy metals.  

Science.gov (United States)

Many industries discharge untreated wastewater into the environment. Heavy metals from many industrial processes end up as hazardous pollutants of wastewaters.Heavy metal pollution has increased in recent decades and there is a growing concern for the public health risk they may pose. To remove heavy metal ions from polluted waste streams, adsorption processes are among the most common and effective treatment methods. The adsorbents that are used to remove heavy metal ions from aqueous media have both advantages and disadvantages. Cost and effectiveness are two of the most prominent criteria for choosing adsorbents. Because cost is so important, great effort has been extended to study and find effective lower cost adsorbents.One class of adsorbents that is gaining considerable attention is agricultural wastes. Among many alternatives, palm oil biomasses have shown promise as effective adsorbents for removing heavy metals from wastewater. The palm oil industry has rapidly expanded in recent years, and a large amount of palm oil biomass is available. This biomass is a low-cost agricultural waste that exhibits, either in its raw form or after being processed, the potential for eliminating heavy metal ions from wastewater. In this article, we provide background information on oil palm biomass and describe studies that indicate its potential as an alternative adsorbent for removing heavy metal ions from wastewater. From having reviewed the cogent literature on this topic we are encouraged that low-cost oil-palm-related adsorbents have already demonstrated outstanding removal capabilities for various pollutants.Because cost is so important to those who choose to clean waste streams by using adsorbents, the use of cheap sources of unconventional adsorbents is increasingly being investigated. An adsorbent is considered to be inexpensive when it is readily available, is environmentally friendly, is cost-effective and be effectively used in economical processes. The advantages that oil palm biomass has includes the following:available and exists in abundance, appears to be effective technically, and can be integrated into existing processes. Despite these advantages, oil palm biomasses have disadvantages such as low adsorption capacity, increased COD, BOD and TOC. These disadvantages can be overcome by modifying the biomass either chemically or thermally. Such modification creates a charged surface and increases the heavy metal ion binding capacity of the adsorbent. PMID:24984835

Vakili, Mohammadtaghi; Rafatullah, Mohd; Ibrahim, Mahamad Hakimi; Abdullah, Ahmad Zuhairi; Salamatinia, Babak; Gholami, Zahra

2014-01-01

335

Vanadium (4) complexing in phase of adsorbent with benzimidazole groups  

International Nuclear Information System (INIS)

Equilibrium and kinetic characteristics of V4+ sorption by POLYORGS XI-H adsorbent with benzimidazole groups (BIm) are investigated. Using ESR method it is stated that [VO2+]:[BIm]1:2 complex, where VO2+ is combined with nitrogen atoms of two imidazole groups, is formed in adsorbent phase. The highest distribution factor of 4.7x103 is attained at pH6

336

USING OF NATURAL ADSORBENTS IN PROCESSES OF PETROLEUM PRODUCTS’ CLEARING  

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Full Text Available  Questions, that concern the ability to use natural sorbent – poligorskite of Cherkassy deposit – in processes of petroleum products’ clearing, are considered. The influence of different methods of samples’ preparation on efficiency of adsorption clearing of furnace fuel, is researched. Comparative characteristic of adsorbent’s selectivity toward different pollutions was made. High effectiveness of using of natural poligorskite for extraction of acidic pollutions from petroleum products was showed.

Sergey V. Ivanov

2008-02-01

337

Development of solid adsorbent materials for CO?capture  

OpenAIRE

The application of solid adsorbents for gas separation in pre-combustion carbon capture from gasification processes has gained attention in recent times. This is due to the potential of the technology to reduce the overall energy penalty associated with the capture process. However, this requires the development of solid adsorbent materials with large selectivity, large adsorption capacity, fast adsorption kinetics for CO2 coupled with good mechanical strength and thermal stability. In this ...

Ogbuka, Chidi Premie

2013-01-01

338

Distribution of adsorbed molecules in electronic nose sensors  

DEFF Research Database (Denmark)

Neutron reflectivity measurements of thin films of electropolymerised poly(pyrrole) show that swelling of these insoluble polymers does occur following vapour adsorption. The variation in swelling found for different vapours is correlated with corresponding changes in polymer conductivity and mass of adsorbed vapour. This correlation suggests that hydrophobic and hydrophilic vapour species adsorb into regions of the membrane with different solvating environments (C) 2000 Elsevier Science B.V. All rights reserved.

Swann, M.J.; Glidle, A.

2000-01-01

339

Development of an adsorbent for both cesium and strontium  

International Nuclear Information System (INIS)

Described is the development of the adsorbent in the title at the process of developing the agent to adsorb each element. For cooling the reactors injured by the Fukushima Nuclear Power Plant Accident by the earthquake and tsunami on the day before (Mar. 11, 2011), fresh/ sea water is supplied in the reactor and flows out contaminated with radioactive elements in the turbine building and then in the treatment plant to remove oil and cesium for re-circulation to the reactor. Water from the plant still contains radioisotopes derived from fission, like 90Sr/90Y at 1.2 x 108 Bq/L and 137Cs/137mBa at 6.1 x 103 Bq/L, and from activation of reactor materials. Before the plant, the water contains 137Cs at the level as high as 4.1 x 107 Bq/L. Authors have examined various agents to adsorb 90Sr and 137Cs with a measure of partition coefficient Kd (L of the artificial sea water/kg) and have come to find out the adsorbent in the title: it is derived from the Cs-adsorbing crystalized silico-titanate (CST). The adsorbent is obtainable by surface treatment of CST with NaOH and has high Kds of >1 x 103 and >1 x 104 L/kg for Sr and Cs, respectively, while other ordinary adsorbents' Kds are: artificial zeolite 1-10 x 102/1-10 x 101 for Sr/Cs, respectively; natural one 0.1-10 x 101/1-10 x 102; ferrocyanide 0.1-10 x 101/1-10 x 104, and CST 1 x 101/>1 x 104. When 1 m3 of the present adsorbent is used, >99% of Cs and Sr can be removable in >3,000 m3 of contaminated water, suggesting its usefulness for dealing with water after the Accident. (T.T.)

340

Linear response theory of activated surface diffusion with interacting adsorbates  

OpenAIRE

Activated surface diffusion with interacting adsorbates is analyzed within the Linear Response Theory framework. The so-called interacting single adsorbate model is justified by means of a two-bath model, where one harmonic bath takes into account the interaction with the surface phonons, while the other one describes the surface coverage, this leading to defining a collisional friction. Here, the corresponding theory is applied to simple systems, such as diffusion on flat s...

Marti?nez Casado, R.; Sanz, A?ngel S.; Vega, J. L.; Rojas Lorenzo, G.; Miret-arte?s, Salvador

2009-01-01

341

Carbon-13 NMR investigation of acetone adsorbed on silica gel  

International Nuclear Information System (INIS)

The 13C chemical shift of acetone adsorbed on silica gel has been measured as a function of adsorbate coverage and concentration of surface hydroxyl groups. The experimental data can be interpreted by a theoretical model for the adsorption, based upon the BET-theory with two different adsorption mechanisms for acetone in the first monomolecular layer (hydrogen bonding and not hydrogen bonding). The concentration of acetone in different adsorption sites and the chemical shift in these sites have been obtained. (orig.)

342

Nature of adsorbed layers of nonionic surfactants on sol particles  

OpenAIRE

The nature of adsorbed layers of hexaethyleneglycol monododecyl ether (C12E6) on ludox silica sols has been determined by small angle neutron scattering. The coated sols show critical opalescence, and the onset of attractive interactions have been observed for both concentrated and dilute sols. The interpretation of the data is consistent with the formation of small islands of surfactant bilayers on the surface, where the thickness of the adsorbed layer is ca. 40 angstrom. At saturation cover...

Penfold, J.; Staples, E.; Cummins, Pg

1990-01-01

343

Structure and Reactivity of Adsorbed Fibronectin Films on Mica  

OpenAIRE

Understanding the interactions of adsorbed fibronectin (Fn) with other biomolecules is important for many biomedical applications. Fn is found in almost all body fluids, in the extracellular matrix, and plays a fundamental role in many biological processes. This study found that the structure (conformation, orientation) and reactivity of Fn adsorbed onto mica is dependent on the Fn surface concentration. Atomic force microscopy and x-ray photoelectron spectroscopy were used to determine the s...

Hull, James R.; Tamura, Glen S.; Castner, David G.

2007-01-01

344

Simulations of the Static Friction Due to Adsorbed Molecules  

OpenAIRE

The static friction between crystalline surfaces separated by a molecularly thin layer of adsorbed molecules is calculated using molecular dynamics simulations. These molecules naturally lead to a finite static friction that is consistent with macroscopic friction laws. Crystalline alignment, sliding direction, and the number of adsorbed molecules are not controlled in most experiments and are shown to have little effect on the friction. Temperature, molecular geometry and i...

He, Gang; Robbins, Mark O.

2001-01-01

345

Electrochemical Studies of Paraquat Adsorbed onto Crystalline Apatite  

OpenAIRE

The carbon paste electrode (CPE) has been used to analyze the electrochemical behavior of paraquat (PQ) adsorbed onto synthesized hydroxyapatite phosphocalcique (HAP) in K2SO4 (0.1M). The cyclic voltammetry results obtained corrobate with square wave voltammetry. The influence of variables such as the concentration of paraquat adsorbed onto apatite (PQ/HAP), and the potential scan rate was tested.X-ray diffraction analysis (XRD), Fourier transformed infrared spectroscopy (FTIR) analysis and i...

El Mhammedi, Moulay Abderrahim; Chtaini, Abdelilah

2007-01-01

346

On the effect of coverage-dependent adsorbate-adsorbate interactions for CO methanation on transition metal surfaces  

DEFF Research Database (Denmark)

Heterogeneously catalyzed reactions involving the dissociation of strongly bonded molecules typically need quite reactive catalysts with high coverages of intermediate molecules. Methanation of carbon monoxide is one example, where CO dissociation has been reported to take place on step sites with a high coverage of CO. At these high coverages, reaction intermediates experience interaction effects that typically reduce their adsorption energies. Herein, the effect of these interactions on the activities of transition metals for CO methanation is investigated. For transition metals that have low coverages of reactants, the effect is minimal. But for materials with high coverages under reaction conditions, rates can change by several orders of magnitude. Nevertheless, the position of the maximum of the activity volcano does not shift significantly, and the rates at the maximum are only slightly perturbed by adsorbate-adsorbate interactions. In order to accurately describe selectivities, however, adsorbate-adsorbate interactions will likely need to be included.

Lausche, Adam C.; Medford, Andrew J.

2013-01-01

347

Some Observations on the Development of Superior Photocatalytic Systems for Application to Water Purification by the “Adsorb and Shuttle” or the Interphase Charge Transfer Mechanisms  

Directory of Open Access Journals (Sweden)

Full Text Available Adsorb and shuttle (A/S and interfacial charge transfer are the two major strategies for overcoming recombination in photocatalysis in this era of nanoparticle composites. Their relationships are considered here. A review of key literature is accompanied by a presentation of three new experiments within the overall aim of assessing the relation of these strategies. The cases presented include: A/S by a high silica zeolite/TiO2 composite, charge transfer (CT between phases in a TiO2/WO3 composite and both A/S and CT by composites of TiO2 with powered activated carbon (AC and single-walled carbon nanotubes (SWCNT. The opportunities presented by the two strategies for moving toward photocatalysts that could support applications for the removal of contaminants from drinking water or that lead to a practical adsorbent for organics that could be regenerated photocatalytically link this discussion to ongoing research here.

Cooper Langford

2014-11-01

348

Tobacco waste/industrial sludge based desulfurization adsorbents: effect of phase interactions during pyrolysis on surface activity.  

Science.gov (United States)

Industrial waste derived adsorbents were obtained by pyrolysis of tobacco waste with either metal sludge or waste oil sludge from a shipyard. The materials were used as media to remove hydrogen sulfide at room temperature in the presence of moisture. The initial and exhausted adsorbents after the breakthrough tests were characterized using sorption of nitrogen, thermal analysis, XRD, elemental analysis, and surface pH measurements. It was found that mixing tobacco and industrial sludges results in a strong synergy, enhancing the catalytic properties of adsorbents. This synergy is observed in both surface chemistry and porosity. During pyrolysis, new mineral phases are formed as a result of solid-state reactions between the components of the sludges. They are highly dispersed on the surface of mesopores. A high volume of these pores is a result of activation of the carbon phase in the composite by alkaline earth metals and also by the release of water from the decomposition of an inorganic phase that is in the predominant quantity. A high temperature of pyrolysis is beneficial for the adsorbents due to the enhanced activation of the carbonaceous phase and the chemical stabilization of the inorganic phase. Samples obtained at low temperatures are sensitive to water, which deactivates their catalytic centers. PMID:17547202

Seredych, Mykola; Bandosz, Teresa J

2007-05-15

349

Mixed composition materials suitable for vacuum web sputter coating  

Science.gov (United States)

Ion beam sputter deposition techniques were used to investigate simultaneous sputter etching of two component targets so as to produce mixed composition films. Although sputter deposition has been largely confined to metals and metal oxides, at least one polymeric material, poly-tetra-fluorethylene, has been demonstrated to produce sputtered fragments which repolymerize upon deposition to produce a highly cross-linked fluoropolymer resembling that of the parent target Fluoropolymer-filled silicon dioxide and fluoropolymer-filled aluminum oxide coatings have been deposited by means of ion beam sputter coat deposition resulting in films having material properties suitable for aerospace and commercial applications. The addition of fluoropolymer to silicon dioxide films was found to increase the hydrophobicity of the resulting mixed films; however, adding fluoropolymer to aluminum oxide films resulted in a reduction in hydrophobicity, thought to be caused by aluminum fluoride formation.

Banks, Bruce A.; Rutledge, Sharon K.; Dever, Joyce A.; Bruckner, Eric J.; Walters, Patricia; Hambourger, Paul D.

1996-01-01

350

Applications of Oxide Coatings in Photovoltaic Devices  

Directory of Open Access Journals (Sweden)

Full Text Available Metalloid and metal based oxides are an almost unavoidable component in the majority of solar cell technologies used at the time of writing this review. Numerous studies have shown increases of ?1% absolute in solar cell efficiency by simply substituting a given layer in the material stack with an oxide. Depending on the stoichiometry and whether other elements are present, oxides can be used for the purpose of light management, passivation of electrical defects, photo-carrier generation, charge separation, and charge transport in a solar cell. In this review, the most commonly used oxides whose benefits for solar cells have been proven both in a laboratory and industrial environment are discussed. Additionally, developing trends in the use of oxides, as well as newer oxide materials, and deposition technologies for solar cells are reported.

Sonya Calnan

2014-03-01

351

Line Shape Broadening in Surface Diffusion of Interacting Adsorbates with Quasielastic He Atom Scattering  

OpenAIRE

The experimental line shape broadening observed in adsorbate diffusion on metal surfaces with increasing coverage is usually related to the nature of the adsorbate-adsorbate interaction. Here we show that this broadening can also be understood in terms of a fully stochastic model just considering two noise sources: (i) a Gaussian white noise accounting for the surface friction, and (ii) a shot noise replacing the physical adsorbate-adsorbate interaction potential. Furthermore, contrary to wha...

Marti?nez Casado, R.; Vega, J. L.; Sanz, A?ngel S.; Miret-arte?s, Salvador

2007-01-01

352

Synthesis of arsenic graft adsorbents in pilot scale  

International Nuclear Information System (INIS)

Synthesis of arsenic (As) adsorbents in pilot scale was carried out with a synthesizing apparatus by radiation-induced graft polymerization of 2-hydroxyethyl methacrylate phosphoric acid monomer (PA), which consists of phosphoric acid mono- (50%) and di- (50%) ethyl methacrylate esters onto a nonwoven cotton fabric (NCF), and following chemical modification by contact with a zirconium (Zr) solution. The apparatus which was equipped with reaction tanks, a washing tank and a pump can produce up to 0.3 m×14 m size of the As(V) adsorbent in one reaction. A degree of grafting of 150% was obtained at an irradiation dose of 20 kGy with 5% of PA solution mixed with deionized water for 1 h at 40 °C. Finally, after Zr(IV) was loaded onto a NCF with 5 mmol/L of Zr(IV) solution, the graft adsorbent for the removal of As(V) was achieved in pilot-scale. The adsorbent which was synthesized in pilot scale was evaluated in batch mode adsorption with 1 ppm (mg/l) of As(V) solution for 2 h at room temperature. As a result, the adsorption capacity for As(V) was 0.02 mmol/g-adsorbent.

353

The influence of adsorbent properties on uranium recovery cost  

International Nuclear Information System (INIS)

The authors made a study as to how the variations of adsorbent properties would affect the unit production cost of uranium when it was extracted from sea water by the pumping and fixed-bed system. The study was conducted on the following assumption : hydrous titanium oxide was used as adsorbent, and the size of a plant was of the production capacity of 1,000 t-U/y. The linear flow rate of sea water, the thickness of the bed, and adsorption time were changed according to the variations of adsorbent properties, and the optimum conditions of plant operation were set up. Taking into consideration of the depression of uranium concentration in sea water along with the direction of water flow in the bed, the amount of uranium adsorbed was calculated by using diffusion equations. The analyses of the system showed that the linear flow rate of sea water was not independent of the bed thickness, and the best combination yielded the minimum uranium cost. The effect of the equilibrated adsorption capacity of adsorbent upon the reduction of the unit production cost was small, but that of the liquid-film mass transfer coefficient kf was pretty large. The optimum adsorption time per cycle was about 25 days. As a result of cost estimations, the unit costs ranged from $289.2/1b to $190.2/1b U3O8 (1976 dollars) were obtained for the plant of the production rate of 1,000 t-U/y. (author)

354

Toward a detailed characterization of oil adsorbates as "solid liquids".  

Science.gov (United States)

Solid lipid formulation systems are used to overcome oral bioavailability problems of poorly water-soluble drugs. One promising process is the conversion of a liquid lipid system in a free flowing powder by use of adsorbing excipients. The aim of this study was the detailed characterization of solid-liquid interactions in oil adsorbed to Fujicalin and Neusilin which were manufactured by means of dual asymmetric centrifugation or conventional mortar/pestle blending. The adsorption strength of the excipients was investigated by Benchtop-NMR and ESR spectroscopy revealing the highest adsorption power for the Neusilin products. The adsorbate production methods as well as the storage of the excipients impact their adsorption properties. Environmental scanning electron microscopy (ESEM) and confocal laser scanning microscopy (CLSM) show that dual asymmetric centrifugation leads to a smoothing of the particle surface, whereas the mortar/pestle blending results in an uneven surface and particle destruction. The oil distribution at the particles is inhomogeneous for both production methods. The micropolarity of the adsorbed oil was investigated by ESR spectroscopy and multispectral fluorescence imaging. The adsorbing process on Neusilin leads to an increased micropolarity of the oil component. The release of the oil component in aqueous media could be verified by Benchtop-NMR and multispectral fluorescence imaging. PMID:23275113

Kutza, Claudia; Metz, Hendrik; Kutza, Johannes; Syrowatka, Frank; Mäder, Karsten

2013-05-01

355

Removal of fluoride from groundwater by adsorption onto La(III)- Al(III) loaded scoria adsorbent  

Energy Technology Data Exchange (ETDEWEB)

The La{sup 3+}-Al{sup 3+} loaded scoria (La-Al-Scoria) was prepared as adsorbent for the fluoride removal from groundwater. The connecting time experiment indicated that the fluoride adsorption process reached equilibrium within 5 hours. The kinetics of fluoride ion adsorption onto La-Al-Scoria was followed the pseudo-second order with correlation coefficient value (R{sup 2}) of 0.997. The isotherm data was well fitted to both of the Freundlich and Langmuir isotherm models, the R{sup 2} of Freundlich and Langmuir were 0.98 and 0.97, respectively. Subsequently, the adsorbent was characterized by scanning electron microscope (SEM), Energy dispersive analysis of X-ray (EDX), X-ray diffraction analysis (XRD) and X-ray Photoelectron Spectroscopy (XPS) measurements. SEM visual expressed that the dense canal surface structure of natural scoria appeared a large amount of rod-like composite after modification. The XRD and XPS instrumental studies revealed that the La{sup 3+} and Al{sup 3+} were loaded on the surface of modified scoria and the fluoride ion was adsorbed on the La-Al-Scoria. The large amount of La-Al-O composite oxide existed onto the surface of La-Al-Scoria was the immanent cause for the excellent adsorption capacity of fluoride ion.

Zhang, Shengyu [Key Laboratory of Songliao Aquatic Environment, Ministry of Education, Jilin Jianzhu University, Changchun 130118 (China); Key Lab of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130026 (China); Institute of Water Resources and Environmental Jilin University, Changchun 130026 (China); Lu, Ying; Lin, Xueyu; Su, Xiaosi [Key Lab of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130026 (China); Institute of Water Resources and Environmental Jilin University, Changchun 130026 (China); Zhang, Yuling, E-mail: zhangyl8@jlu.edu.cn [Key Lab of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130026 (China); Institute of Water Resources and Environmental Jilin University, Changchun 130026 (China)

2014-06-01

356

Removal of fluoride from groundwater by adsorption onto La(III)- Al(III) loaded scoria adsorbent  

International Nuclear Information System (INIS)

The La3+-Al3+ loaded scoria (La-Al-Scoria) was prepared as adsorbent for the fluoride removal from groundwater. The connecting time experiment indicated that the fluoride adsorption process reached equilibrium within 5 hours. The kinetics of fluoride ion adsorption onto La-Al-Scoria was followed the pseudo-second order with correlation coefficient value (R2) of 0.997. The isotherm data was well fitted to both of the Freundlich and Langmuir isotherm models, the R2 of Freundlich and Langmuir were 0.98 and 0.97, respectively. Subsequently, the adsorbent was characterized by scanning electron microscope (SEM), Energy dispersive analysis of X-ray (EDX), X-ray diffraction analysis (XRD) and X-ray Photoelectron Spectroscopy (XPS) measurements. SEM visual expressed that the dense canal surface structure of natural scoria appeared a large amount of rod-like composite after modification. The XRD and XPS instrumental studies revealed that the La3+ and Al3+ were loaded on the surface of modified scoria and the fluoride ion was adsorbed on the La-Al-Scoria. The large amount of La-Al-O composite oxide existed onto the surface of La-Al-Scoria was the immanent cause for the excellent adsorption capacity of fluoride ion.

357

Removal of fluoride from groundwater by adsorption onto La(III)- Al(III) loaded scoria adsorbent  

Science.gov (United States)

The La3+-Al3+ loaded scoria (La-Al-Scoria) was prepared as adsorbent for the fluoride removal from groundwater. The connecting time experiment indicated that the fluoride adsorption process reached equilibrium within 5 hours. The kinetics of fluoride ion adsorption onto La-Al-Scoria was followed the pseudo-second order with correlation coefficient value (R2) of 0.997. The isotherm data was well fitted to both of the Freundlich and Langmuir isotherm models, the R2 of Freundlich and Langmuir were 0.98 and 0.97, respectively. Subsequently, the adsorbent was characterized by scanning electron microscope (SEM), Energy dispersive analysis of X-ray (EDX), X-ray diffraction analysis (XRD) and X-ray Photoelectron Spectroscopy (XPS) measurements. SEM visual expressed that the dense canal surface structure of natural scoria appeared a large amount of rod-like composite after modification. The XRD and XPS instrumental studies revealed that the La3+ and Al3+ were loaded on the surface of modified scoria and the fluoride ion was adsorbed on the La-Al-Scoria. The large amount of La-Al-O composite oxide existed onto the surface of La-Al-Scoria was the immanent cause for the excellent adsorption capacity of fluoride ion.

Zhang, Shengyu; Lu, Ying; Lin, Xueyu; Su, Xiaosi; Zhang, Yuling

2014-06-01

358

Surface modification of chromatography adsorbents by low temperature low pressure plasma  

DEFF Research Database (Denmark)

In this study we show how low temperature glow discharge plasma can be used to prepare bi-layered chromatography adsorbents with non-adsorptive exteriors. The commercial strong anion exchange expanded bed chromatography matrix, Q HyperZ, was treated with plasmas in one of two general ways. Using a purpose-designed rotating reactor, plasmas were employed to either: (i) remove anion exchange ligands at or close to the exterior surface of Q HyperZ, and replace them with polar oxygen containing functions (‘plasma etching and oxidation’); or (ii) bury the same surface exposed ligands beneath thin polymer coatings (‘plasma polymerization coating’) using appropriate monomers (vinyl acetate, vinyl pyrrolidone, safrole) and argon as the carrier gas. X-ray photoelectron spectroscopy analysis (first 10 nm depth) of Q HyperZ before and after the various plasma treatments confirmed that substantial changes to the elemental composition of Q HyperZ's exterior had been inflicted in all cases. The atomic percent changes in carbon, nitrogen, oxygen, yttrium and zirconium observed after being exposed to air plasma etching were entirely consistent with: the removal of pendant Q (trimethylammonium) functions; increased exposure of the underlying yttrium-stabilised zirconia shell; and introduction of hydroxyl and carbonyl functions. Following plasma polymerization treatments (with all three monomers tested), the increased atomic percent levels of carbon and parallel drops in nitrogen, yttrium and zirconium provided clear evidence that thin polymer coats had been created at the exteriors of Q HyperZ adsorbent particles. No changes in adsorbent size and surface morphology, nor any evidence of plasma-induced damage could be discerned from scanning electron micrographs, light micrographs and measurements of particle size distributions following 3 h exposure to air (220 V; 35.8 W L?1) or ‘vinyl acetate/argon’ (170 V; 16.5 W L?1) plasmas. Losses in bulk chloride exchange capacity before and after exposure to plasmas enabled effective modification depths within hydrated Q HyperZ adsorbent particles to be calculated as 0.2–1.2 ?m, depending on the conditions applied. The depth of plasma induced alteration was strongly influenced by the power input and size of the treated batch, i.e. dropping the power or increasing the batch size resulted in reduced plasma penetration and therefore shallower modification. The selectivity of ‘surface vs. core’ modification imparted to Q HyperZ by the various plasma treatments was evaluated in static and dynamic binding studies employing appropriate probes, i.e. plasmid DNA, sonicated calf thymus DNA and bovine serum albumin. In static binding studies performed with adsorbents that had been exposed to plasmas at the 5 g scale (25 g L?1 of plasma reactor), the highest ‘surface/core’ modification selectivity was observed for Q HyperZ that had been subjected to 3 h of air plasma etching at 220 V (35.8 W L?1). This treatment removed 53% of ‘surface’ DNA binding at the expense of a 9.3% loss in ‘core’ protein binding. Even more impressive results were obtained in dynamic expanded bed adsorption studies conducted with Q HyperZ adsorbents that had been treated with air (220 V, 3 h) and ‘vinyl acetate/argon’ (170 V, 3 h) plasmas at 10.5 g scale (52.5 g L?1 of plasma reactor). Following both plasma treatments: the 10% breakthrough capacities of the modified Q HyperZ adsorbents towards ‘surface’ binding DNA probes dropped very significantly (30–85%); the DNA induced inter-particle cross-linking and contraction of expanded beds observed during application of sonicated DNA on native Q HyperZ was completely eradicated; but the ‘core’ protein binding performance remained unchanged cf. that of the native Q HyperZ starting material.

Arpanaei, Ayyoob; Winther-Jensen, BjØrn

2010-01-01

359

Adsorption of copolymers aggregates: from kinetics to adsorbed layer structure.  

Science.gov (United States)

We examined the adsorption, on hydrophobic and hydrophilic surfaces, of 4 rake-type poly(dimethyl siloxane) (PDMS) copolymers varying the amount of poly(ethylene glycol) (PEG) graft arms from 41 to 72%. The copolymers formed large aggregates in solution, complicating their adsorption kinetics and layer structures. We found the adsorption process always to be dominated by the adsorption of large aggregates, with strongly bound layers resistant to rinsing in adsorbing buffer. Adsorbed amounts were nearly independent of the substrate. However, subtleties in the adsorption kinetics suggested different layer structures for the different systems. On hydrophilic silica, aggregates adsorbed at the transport limited rate until surface saturation, and associated interfacial structures were likely retained. On the hydrophobic surface, a subset of the copolymers exhibited retarded late stage adsorption kinetics suggestive of brush formation. This work demonstrates how subtle differences in adsorption kinetics provide insight into potential interfacial layer structures. PMID:18436230

Zdyrko, Bogdan; Ofir, Pazit Bar-Yosef; Alb, Alina M; Reed, Wayne F; Santore, Maria M

2008-06-15

360

High-performances carbonaceous adsorbents for hydrogen storage  

International Nuclear Information System (INIS)

Activated carbons (ACs) with controlled microporosity have been prepared and their H2 storage performances have been tested in a gravimetric device. Such adsorbents are natural Chinese anthracites chemically activated with alkaline hydroxides, NaOH or KOH. Outstanding total storage capacities of hydrogen, as high as 6.6wt.% equivalent to excess capacity of 6.2 wt.%, have been obtained at 4MPa for some of these adsorbents. These values of hydrogen adsorption are among the best, if not the highest, ever published so far in the open literature. They are well above those of some commercial materials, e.g. Maxsorb-3, considered as a reference of high-performance adsorbent for hydrogen adsorption. Such exceptional storage capacities may be ascribed to a higher volume of micropores (< 2nm).

361

Electronic and electrochemical doping of graphene by surface adsorbates  

Science.gov (United States)

Summary Many potential applications of graphene require its precise and controllable doping with charge carriers. Being a two-dimensional material graphene is extremely sensitive to surface adsorbates, so its electronic properties can be effectively modified by deposition of different atoms and molecules. In this paper, we review two mechanisms of graphene doping by surface adsorbates, namely electronic and electrochemical doping. Although, electronic doping has been extensively studied and discussed in the literature, much less attention has been paid to electrochemical doping. This mechanism can, however, explain the doping of graphene by adsorbates for which no charge transfer is expected within the electronic doping model. In addition, electrochemical doping is in the origin of the hysteresis effects often observed in graphene-based field effect transistors when operating in the atmospheric environment. PMID:25383296

Markevich, Alexander

2014-01-01

362

Viability of banana pith use as adsorbent for uranium ions  

International Nuclear Information System (INIS)

In this work banana pith was investigated as adsorbent for uranium ions from nitric solutions. The use of this type of biomaterial reduces environmental impact of two forms, the banana pith that is considered a pollutant, is removed of place where was generated or deposited and contaminated effluents can be treated by this residual biomass. One another important aspect is the reutilization of both biomass and metals adsorbed that can be recovered by desorption processes. It is a natural material of low cost and easy application. Influence of adsorbent size and adsorption kinetic were studied. The studies of adsorption followed both Langmuir and Freundlich models. In concentration range of 0.1 - 4.0 g/L, the adsorption process was described better by Freundlich equation. (author)

363

Radioactive diffusion gaseous probe technique for study adsorbent structure inhomogeneity  

International Nuclear Information System (INIS)

One of the versions of the method of diffusion gaseous probe - method of longitudinal shear in combination with autoradiography (ARG) - was used for characterising sorbents and catalysts, which are considered to be promising for reprocessing of sulfur-containing natural gases. Hydrogen sulfide, labelled with 35S was used as diffusion radioactive probe. Zeolite granules of 4A type and granulated adsorbents on the basis of CR and AM aluminium oxides, which are industrial catalysts of Clauss reaction developed at SNEA company, were used as objects under investigation. It is shown that technique for fabrication of 4A zeolite granules leads to asymmetrical pore distribution over the granule diameter. Technique for AM granule fabrication leads to occuRrence of local inhomogeneities of the structure in the form of narrow coaxial rings with decreased or increased local adsorption ability. Granules of adsorbent of CR type are characterized by rather homogeneous structure. It is recommended to use the mentioned method for industrial adsorbent diagnosis

364

Study on the distribution of binary mixed counterions in surfactant adsorbed films by total reflection XAFS measurements.  

Science.gov (United States)

The total reflection X-ray absorption fine structure (TR-XAFS) technique was applied to adsorbed films at the surface of aqueous solutions of surfactant mixtures composed of dodecyltrimethylammonium bromide (DTAB) and dodecyltrimethylammonium tetrafluoroborate (DTABF(4)). The obtained XAFS spectra were expressed as linear combinations of two specific spectra corresponding to fully hydrated bromide ions (free-Br) and partially dehydrated bromide ions adsorbed to the hydrophilic groups of surfactant ions (bound-Br) at the surface. The ratio of free- and bound-Br ions was determined as a function of surface tension and surface composition of the surfactants. Taking also the results in our previous studies on the DTAB - dodecyltrimethylammonium chloride (DTAC) and 1-hexyl-3-methylimidazolium bromide (HMIMBr) - 1-hexyl-3-methylimidazolium tetrafluoroborate (HMIMBF(4)) mixed systems into consideration, the relation between counterion distribution and miscibility of counterions at the solution surface was deduced for the surfactant mixtures having common surfactant ions but different counterions. PMID:23014451

Imai, Y; Li, H H; Takumi, H; Tanida, H; Watanabe, I; Takiue, T; Matsubara, H; Aratono, M

2012-12-15

365

Heat transfer between adsorbate and laser-heated hot electrons  

Energy Technology Data Exchange (ETDEWEB)

Strong short laser pulses can give rise to a strong increase in the electronic temperature at metal surfaces. Energy transfer from the hot electrons to adsorbed molecules may result in adsorbate reactions, e.g. desorption or diffusion. We point out the limitations of an often used equation to describe the heat transfer process in terms of a friction coupling. We propose a simple theory for the energy transfer between the adsorbate and hot electrons using a newly introduced heat transfer coefficient, which depends on the adsorbate temperature. We calculate the transient adsorbate temperature and the reaction yield for a Morse potential as a function of the laser fluency. The results are compared to those obtained using a conventional heat transfer equation with temperature-independent friction. It is found that our equation of energy (heat) transfer gives a significantly lower adsorbate peak temperature, which results in a large modification of the reaction yield. We also consider the heat transfer between different vibrational modes excited by hot electrons. This mode coupling provides indirect heating of the vibrational temperature in addition to the direct heating by hot electrons. The formula of heat transfer through linear mode-mode coupling of two harmonic oscillators is applied to the recent time-resolved study of carbon monoxide and atomic oxygen hopping on an ultrafast laser-heated Pt(111) surface. It is found that the maximum temperature of the frustrated translation mode can reach high temperatures for hopping, even when direct friction coupling to the hot electrons is not strong enough.

Ueba, H [Graduate School of Science and Engineering, University of Toyama, Toyama (Japan); Persson, B N J [IFF, FZ-Juelich, Postfach 1913, 52425 Juelich (Germany)], E-mail: ueba@eng.u-toyama.ac.jp

2008-06-04

366

Cauliflower-like CuI nanostructures: Green synthesis and applications as catalyst and adsorbent  

International Nuclear Information System (INIS)

Highlights: ? In this study we report a green, environment-friendly, efficient, and direct one-step process for the preparation of CuI cauliflower. ? The as-formed CuI cauliflower shows excellent catalytic activity for coupling reaction between benzylamine and iodobenzene. ? The cauliflower-like CuI nanostructures have been successfully demonstrated as adsorbent for Cd (II) with high removal capacity. ? To the best of our knowledge, it is the first report that nanostructured CuI acts as catalyst for coupling reaction and adsorbent for heavy metal ion. ? It is also a good example for the organic combination of green chemistry and functional materials. - Abstract: Cauliflower-like CuI nanostructures is realized by an ampicillin-assisted clean, nontoxic, environmentally friendly synthesis strategy at room temperature. The morphology, composition, and phase structure of as-prepared powders were characterized by field emission scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The results show that ampicillin plays dual roles, reducing and morphology-directing agents, in the formation of the products. A possible growth mechanism of the cauliflower-like CuI nanostructures is tentatively proposed. The preliminary investigations show that the cauliflower-like CuI structure not only exhibits high catalytic activity with respect to coupling reaction between benzylamine and iodobenzene but also possesses high removal capacity for Cd es high removal capacity for Cd (II), which may be ascribed to the high specific surface area of the special configuration. To the best of our knowledge, it is the first report that cauliflower-like CuI nanoparticles act as catalyst for coupling reaction and adsorbent for heavy metal ion.

367

Removal of uranium by the adsorbents produced from coffee residues  

International Nuclear Information System (INIS)

Large amounts of coffee residues contaminate the environment and reprocessing of them as valuable products such as adsorbents will be a good solution from an environmental and economic point of view. In this study some adsorbents were produced from coffee residues and used for batch removal experiments of uranium from aqueous solutions. The adsorption kinetics was found to follow the Lagergren equation. The adsorption process was described with the Langmuir and Freundlich isotherms. Additionally, the effect of different cations on the adsorption of uranium was studied. (author)

368

Iodine fission product mass transfer in adsorbent media  

International Nuclear Information System (INIS)

The iodine and methyl iodide removal efficiency of new and exposed adsorbent media was evaluated using tracer techniques. Particular attention was paid to keep the inlet iodine concentration near the atmospheric iodine concentration of 10-3 ?g/m3. The zone depth of activity was measured at 5.08--81.28 cm/sec (10--160 fpm) in a segmented adsorber system. The obtained results are useful for both the design of air cleaning systems and iodine fission product sampling cartridges. (U.S.)

369

Structural characterization of adsorbed helical and beta-sheet peptides  

Science.gov (United States)

Adsorbed peptides on surfaces have potential applications in the fields of biomaterials, tissue engineering, peptide microarrays and nanobiotechnology. The surface region, the "biomolecular interface" between a material and the biological environment, plays a crucial role in these applications. As a result, characterization of adsorbed peptide structure, especially with respect to identity, concentration, spatial distribution, conformation and orientation, is important. The present research employs NEXAFS (near-edge X-ray absorption fine structure spectroscopy) and SFG (sum frequency generation spectroscopy) to provide information about the adsorbed peptide structure. Soft X-ray NEXAFS is a synchrotron-based technique which typically utilizes polarized X-rays to interrogate surfaces under ultra-high vacuum conditions. SFG is a non-linear optical technique which utilizes a combination of a fixed visible and a tunable infrared laser beams to generate a surface-vibrational spectrum of surface species. SFG has the added advantage of being able to directly analyze the surface-structure at the solid-liquid interface. The main goals of the present research were twofold: characterize the structure of adsorbed peptides (1) ex situ using soft X-ray NEXAFS, and (2) in situ using non-linear laser spectroscopy (SFG). Achieving the former goal involved first developing a comprehensive characterization of the carbon, nitrogen and oxygen k-edge NEXAFS spectra for amino acids, and then using a series of helical and beta-sheet peptides to demonstrate the sensitivity of polarization-dependent NEXAFS to secondary structure of adsorbed peptides. Characterizing the structure of adsorbed peptides in situ using SFG involved developing a model system to probe the solid-liquid interface in situ; demonstrating the ability to probe the molecular interactions and adsorbed secondary structure; following the time-dependent ordering of the adsorbed peptides; and establishing the ability to obtain high-resolution peptide-surface interactions in situ. The results from the present research establish SFG and NEXAFS as powerful techniques for chemical and structural characterization of surfaces and biomolecules immobilized onto those surfaces.

Samuel, Newton Thangadurai

370

Surface forces and narorheological properties of adsorbed polymer monolayers.  

OpenAIRE

This thesis is concemed with the behaviour of adsorbed polymer layers at the solid-liquid interface. The instrument that plays a central role is the so-called Surface Forces Apparatus (SFA), that allows for direct measurement of the interaction between two surfaces as a function of their separation. By applying adsorbed polymer layers to one or both of the surfaces, the interactions between a polymer layer and a bare surface or between two polymer layers can be measured in a liquid medium....

Belder, Gerald Frederik

1995-01-01

371

Regenerable adsorbents for removal of arsenic from contaminated waters and synthesis and characterization of multifunctional magnetic nanoparticles for environmental and biomedical applications  

Science.gov (United States)

The present work is divided into two sections. The first section deals with the synthesis of regenerable adsorbents for the removal of arsenic from contaminated waters. An adsorbent based on carboxymethylated polyethylenimine grafted agarose gels was synthesized and characterized as a regenerable synthetic ferric oxide adsorbent with high capacity for arsenate ions at pH 3.0. Similarly, four metal ion chelating adsorbents based on dipicolylamine were synthesized and characterized with respect to their Cu(II), Fe(III) and As(V) adsorption capacities. The most efficient adsorbents were Nov-PEI-DPA and Nov-TREN-DPA. Additionally, a commercial ion exchange resin was modified with permanganate to oxidize arsenite into arsenate. A complete oxidation-adsorption system was proposed in which a column packed with the oxidation resin was connected in series with an adsorbent column composed of the polyethylenimine grafted agarose gels. The second section involved work with magnetic nanoparticles. First, composite adsorbents consisting of magnetic particles encapsulated within agarose beads with and without grafted iminodiacetic acid (IDA) chelating groups were synthesized. The adsorption capacity of the adsorbents for Cu(II), Fe(III) and As(V) at different concentrations was investigated. Batch experiments were carried out to determine the Fe(III) and As(V) adsorption isotherms for the magnetic Novarose-IDA. Regenerability of the adsorbent was achieved with a pH change of the inlet solution, without affecting its magnetic or adsorption properties. Magnetic composite particles were synthesized for biomedical applications. First, magnetic nanoparticles were coated with silica and then used for gold nanoshell production. These nanoshells were functionalized with a Brij S10 derivative, containing carboxylic groups, using dodecanethiol as a bridging agent to incorporate a fluorescent biomolecule. Finally, magnetic and gold particles were encapsulated in PLGA nanoparticles. Docetaxel was loaded on these multifunctional nanoparticles and released studies were performed at 37°C. The presence of magnetite, colloidal gold and gold nanoshells in the PLGA nanoparticles was revealed by the coloration acquired by the polymeric nanoparticles. The release of drug from the polymeric nanoparticles showed a biphasic behavior with an initial burst followed by a prolonged slow release. There was no effect of the presence of magnetic or metallic particles on docetaxel release.

Verdugo Gonzalez, Brenda

372

Alkali-induced nanopatterning of Ag(110) surface mediated by molecular adsorbate  

Energy Technology Data Exchange (ETDEWEB)

It is known for decades that alkali metals initiate the restructuring of fcc metal surfaces resulting in a composite patterned morphology. On the other hand, co-adsorbed metal atoms and organic molecules often form extended 2D networks due to the metal-molecular coordination reaction. Here we report on a new type of structural modification of the molecule-substrate interface, which is not only restricted to self-assembly of the adsorbed metal atoms and molecules, but it also involves significant morphological reorganization of the metallic surface. In the experiments, potassium atoms are deposited on a monolayer of the long-range ordered PTCDA/Ag(110) phase. Subsequent annealing forces potassium atoms to intercalate under the molecular layer partially unbinding PTCDA from the substrate. The complex interaction between potassium, PTCDA and substrate induces a significant silver mass-transfer and leads to the appearance of 1D stripe-structures of K atoms and PTCDA molecules on a nanopatterned silver surface. Structural and electronic properties of this pattern were studied by means of NIXSW, XPS, LEED and LT-STM.

Mercurio, Giuseppe; Willenbockel, Martin; Weiss, Christian; Temirov, Ruslan; Subach, Sergey; Tautz, Stefan [Peter Gruenberg Institut (PGI-3), Forschungszentrum Juelich, 52425 Juelich (Germany); JARA-Fundamentals of Future Information Technology (Germany); Bauer, Oliver; Fiedler, Benjamin; Sokolowski, Moritz [Institute for Physical and Theoretical Chemistry, University of Bonn (Germany)

2011-07-01

373

Dipodal ferrocene-based adsorbate molecules for self-assembled monolayers on gold.  

Science.gov (United States)

1,1'-Difunctionalised ferrocene derivatives have been studied, which contain groups suitable for chemisorption on gold substrates, namely -NC, -PR(2) as well as a range of sulfur-containing units like -NCS, -SR, and thienyl. Thin films on gold have been fabricated from solution with most of these adsorbate species. Film thickness, composition and structure were investigated primarily by X-ray photoelectron and near-edge X-ray absorption fine-structure spectroscopy. The quality of self-assembled monolayers fabricated from 1,1'-diisocyanoferrocene (1) and 1,1'-diisothiocyanatoferrocene (2) turned out to be superior to that of films based on the other adsorbate species investigated. In addition to the surface coordination behaviour of 1 towards gold substrates, relevant aspects of the molecular coordination chemistry of 1 have also been addressed, including the synthesis and characterisation of [(mu-1){Cr(CO)(5)}(2)], [Ag(2)(mu-1)(2)](NO(3))(2) x H(2)O and [(mu-1)(AuCl)(2)]. The crystal structure of the gold complex is governed by aurophilic interactions and can be taken as a model for the arrangement of 1 in self-assembled monolayers on gold. PMID:18366048

Weidner, Tobias; Ballav, Nirmalya; Zharnikov, Michael; Priebe, Andreas; Long, Nicholas J; Maurer, Jörg; Winter, Rainer; Rothenberger, Alexander; Fenske, Dieter; Rother, Dag; Bruhn, Clemens; Fink, Heinrich; Siemeling, Ulrich

2008-01-01

374

Development of long-life-cycle tablet ceramic adsorbent for geosmin removal from water solution  

Science.gov (United States)

In this study, the tablet ceramic adsorbent (TCA), a silica/iron(III) oxide composite material, has been developed for geosmin (GSM) removal from the water solution. The physicochemical characteristics of TCA were examined with XRD, SEM, EDX and BET analyses. The sorption characteristics of GSM on TCA were investigated in a batch system. Attempts have been made to understand the adsorption kinetics, the effect of initial GSM concentration, solution pH, and reaction time. The batch experiments equilibrium data were well fitted to the Lagergren kinetic equation, which indicate the first-order nature adsorption. Over 82% of the GSM was removed by the TCA within 600 min at an initial concentration of 200 ng/L with 20 g/L of TCA dose. The batch and regeneration study indicated that the TCA is a cost-effective GSM adsorbent with sufficient mechanical strength to retain its physical integrity after long-time adsorption, and high regeneration performance for long-life-cycle application. Almost no second contamination (toxic sludge or leached iron) was observed after adsorption, and the gas resultant of thermal regeneration is harmless to atmospheric environment.

Chen, Rongzhi; Xue, Qiang; Zhang, Zhenya; Sugiura, Norio; Yang, Yingnan; Li, Miao; Chen, Nan; Ying, Zhao; Lei, Zhongfang

2011-01-01

375

Selection of non-adsorbing alkali components  

Energy Technology Data Exchange (ETDEWEB)

This project consists of three phases of laboratory experimental study. In phase I (screening), eight candidate materials, 304SS (serves as a base material for comparison), Hastelloy C-276, Hastelloy X, Haynes No. 188, Allonized 304SS, Pt-coated 304SS, and ceramic-coated 304SS, will be subjected to atmospheric TGA study under the simulated PFBC (oxidizing) environment with and without alkali vapor doping. Each candidate material will be evaluated for its resistance toward alkali-vapor capture. In addition, a post-test metallographic characterization of the sample will be performed to obtain a better understanding of the alkali capture mechanism and material behavior. The material(s) with little or no alkali-vapor adsorption will be selected as the promising material(s) for the Phase II study. In Phase II, the promising material(s) will be further tested in the TGA under elevated pressure to simulate the PFBC environment (in terms of temperature, pressure, and gas composition). The effect of pressure on the extent of alkali-vapor adsorption will be evaluated, and the test samples will be metallographically characterized. The most promising candidate material(s) will be identified and recommended for further tesfing in the actual PFBC environment. In Phase III, four materials will be selected from the eight candidate materials screened in the PFBC environment and will be evaluated for their alkali-vapor capture by atmospheric TGA under the coal gasification fuel gas (reducing) environment. The tested samples will also be metallographically characterized. The most promising material(s) will be identified and recommended for further testing in the actual coal gasification environment.

Lee, S.H.D.; Natesan, K.; Swift, W.M.

1992-11-01

376

Abnormally high light absorption by pigments adsorbed on metals  

Science.gov (United States)

An abnormally high extinction coefficient (almost 100 times as high as in solution) has been found for chlorophyll and pheophytin adsorbed on a smooth metal. These and some literature data suggest this phenomenon may be rather general, particularly for substances having a system of conjugated bonds.

Khanova, L. A.; Tarasevich, M. R.

1983-11-01

377

Adsorption of Iron by Fly Ash Adsorbent of Coal  

Directory of Open Access Journals (Sweden)

Full Text Available Normal 0 false false false IN X-NONE X-NONE MicrosoftInternetExplorer4 Normal 0 false false false IN X-NONE X-NONE MicrosoftInternetExplorer4 This research has investigated adsorption of Fe with using fly ash adsorbent. Phases of adsorption of Fe is activated with H2SO4 after that the fly ash were characterized by using XRF, FTIR and SEM. Determination of optimum conditions on the adsorption of Fe with adsorbent mass variations, variations in contact time, pH variation and variation concentration and adsorption isotherm study. Resulth show that the adsorption of Fe in optimum condition occurs in adsorbent mass of 2.5 g, for 60 minutes contact time with pH 4 at a concentration of 20 ppm. The results also able to adsorp up to 94% Fe. The adsorption of Fe with using fly ash adsorbent was more fitted to the Langmuir model than to Freundlich model

Candra Irawan

2014-04-01

378

IR spectroscopy of adsorbates on ultrathin metal films  

Energy Technology Data Exchange (ETDEWEB)

Metal films with thickness in the nanometer range are optically transparent. With IR transmittance spectroscopy the in-plane film conductivity with its correlation to the film-growth process can be studied without electrical contacts and, on metal-island films, adsorbate vibrations can be observed because of surface enhanced IR absorption (SEIRA). Their analysis enables insight into the adsorbate-metal bonding and therefore gives information on the available adsorption sites and the crystalline facets correlated to. As in IR reflection absorption spectra dipole-dipole interaction of molecules on different sites modifies the vibration lines according to the degree of disorder (''atomic roughness''). Depending on that roughness IR spectra of adsorbate vibrations may be further modified because of their interaction with electronic excitations of the film. So, the limited facet size on cold-condensed metal films leads to additional IR activity: Raman lines of certain centrosymmetric adsorbate molecules (C{sub 2}H{sub 4}) are observed. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Pucci, Annemarie [Kirchhoff-Institut fuer Physik, Ruprecht-Karls-Universitaet, Im Neuenheimer Feld 227, 69120 Heidelberg (Germany)

2005-11-01

379

Substrate induced ordering of molecular adsorbates on Au(111)  

International Nuclear Information System (INIS)

Using scanning tunneling microscopy in dimethylformate, [Ru(bpy)2(bpy-(CH2)x-bpy)2+] (x = 4 and 5) monolayers adsorbed on the unreconstructed and ?3 x 22 reconstructed surfaces of Au(111) were imaged in this paper. The substrate had a highly ordered pattern on the reconstructed surface, but random spatial distribution on the unreconstructed surface. 17 refs., 3 figs

380

Adsorption of remazol brilliant blue on an orange peel adsorbent  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese A novel orange peel adsorbent developed from an agricultural waste material was characterised and utilised for the removal of Remazol Brilliant Blue from an artificial textile-dye effluent. The adsorption thermodynamics of this dye-adsorbent pair was studied in a series of equilibrium experiments. T [...] he time to reach equilibrium was 15 h for the concentration range of 30 mg L-1 to 250 mg L-1. The adsorption capacity decreased with increasing temperature, from 9.7 mg L-1 at 20 ºC to 5.0 mg L-1 at 60 ºC. Both the Langmuir and Freundlich isotherm models fitted the adsorption data quite reasonably. The thermodynamic analysis of dye adsorption onto the orange peel adsorbent indicated its endothermic and spontaneous nature. Thus, the application of orange peel adsorbent for the removal of dye from a synthetic textile effluent was successfully demonstrated. Abstract in english [...

M. R., Mafra; L., Igarashi-Mafra; D. R., Zuim; É. C., Vasques; M. A., Ferreira.

2013-09-01

381

Pulling adsorbed self-avoiding walks from a surface  

International Nuclear Information System (INIS)

We consider a self-avoiding walk model of polymer adsorption where the adsorbed polymer can be desorbed by the application of a force, concentrating on the case of the square lattice. Using series analysis methods we investigate the behaviour of the free energy of the system when there is an attractive potential ? with the surface and a force f applied at the last vertex, normal to the surface, and extract the phase boundary between the ballistic and adsorbed phases. We believe this to be exact to graphical accuracy. We give precise estimates of the location of the transition from the free phase to the ballistic phase, which we find to be at yc = exp?(f/kBTc) = 1, and from the free phase to the adsorbed phase, which we estimate to be at ac = exp?( ? ?/kBTc) = 1.775?615 ± 0.000?005. In addition we prove that the phase transition from the ballistic to the adsorbed phase is first order. (paper)

382

Hydraulic properties of adsorbed water films in unsaturated porous media  

Energy Technology Data Exchange (ETDEWEB)

Adsorbed water films strongly influence residual water saturations and hydraulic conductivities in porous media at low saturations. Hydraulic properties of adsorbed water films in unsaturated porous media were investigated through combining Langmuir's film model with scaling analysis, without use of any adjustable parameters. Diffuse double layer influences are predicted to be important through the strong dependence of adsorbed water film thickness (f) on matric potential ({Psi}) and ion charge (z). Film thickness, film velocity, and unsaturated hydraulic conductivity are predicted to vary with z{sup -1}, z{sup -2}, and z{sup -3}, respectively. In monodisperse granular media, the characteristic grain size ({lambda}) controls film hydraulics through {lambda}{sup -1} scaling of (1) the perimeter length per unit cross sectional area over which films occur, (2) the critical matric potential ({Psi}{sub c}) below which films control flow, and (3) the magnitude of the unsaturated hydraulic conductivity when {Psi} < {Psi}{sub c}. While it is recognized that finer textured sediments have higher unsaturated hydraulic conductivities than coarser sands at intermediate {Psi}, the {lambda}{sup -1} scaling of hydraulic conductivity predicted here extends this understanding to very low saturations where all pores are drained. Extremely low unsaturated hydraulic conductivities are predicted under adsorbed film-controlled conditions (generally < 0.1 mm y{sup -1}). On flat surfaces, the film hydraulic diffusivity is shown to be constant (invariant with respect to {Psi}).

Tokunaga, Tetsu K.

2009-03-01

383

Linear alcohols adsorbed on graphite from the liquid  

Energy Technology Data Exchange (ETDEWEB)

A combination of sensitive calorimetry and neutron diffraction data is presented demonstrating the formation of solid monolayers for linear alcohols (c5 to c19) adsorbed from their liquids to a graphite surface. The results reveal a significant odd-even variation in the monolayer melting points, much bigger than the bulk alcohols, that appears to be structural in origin. (orig.)

Clarke, S.; Messe, L.; Whitehead, C. [Department of Chemistry and BP Institute, Madingley Rise, Madingley Road, Cambridge (United Kingdom); Inaba, A. [Department of Chemistry, Graduate School of Science, Osaka University, Osaka (Japan); Thomas, R.; Arnold, T. [Physical and Theoretical Chemistry Laboratory, South Parks Road, Oxford (United Kingdom)

2002-07-01

384

Utilization of Roselle charcoal as nitrate-nitrogen adsorbent  

Directory of Open Access Journals (Sweden)

Full Text Available Recently, the attempts have been made by utilizing natural material as an adsorbent for wastewater treatment due to its low cost, low energy requirement and the fewer chemicals used. In this study, Roselle (Hibiscus sabdariffa L. var. altissima was prepared to use as a charcoal adsorbent in the treatment process. The nitrate-nitrogen adsorption capacities of Roselle charcoal with 2 different particle sizes, A (4.75- .30 mm and B (2.00-4.75 mm were measured and compared with an activated carbon (AC. The equilibrium data fitted well with the Freundlich Isotherm. The K values related to the capacity of adsorbent for nitratenitrogen of such charcoal studied were in the following orders: AC > B > A expressed as 0.0321, 0.0147 and 0.0071 respectively. In addition, activated carbon required less contact time to reach equilibrium than both of Roselle charcoal A and B. Although removal efficiency of activated carbon was higher than that of Roselle charcoal, Roselle charcoal is an interesting alternative adsorbent due to the lower cost of its production.

Yimrattanabovorn, J.

2006-11-01

385

Activation volumes of enzymes adsorbed on silica particles.  

Science.gov (United States)

The immobilization of enzymes on carrier particles is useful in many biotechnological processes. In this way, enzymes can be separated from the reaction solution by filtering and can be reused in several cycles. On the other hand, there is a series of examples of free enzymes in solution that can be activated by the application of pressure. Thus, a potential loss of enzymatic activity upon immobilization on carrier particles might be compensated by pressure. In this study, we have determined the activation volumes of two enzymes, ?-chymotrypsin (?-CT) and horseradish peroxidase (HRP), when they are adsorbed on silica particles and free in solution. The experiments have been carried out using fluorescence assays under pressures up to 2000 bar. In all cases, activation volumes were found to depend on the applied pressure, suggesting different compressions of the enzyme-substrate complex and the transition state. The volume profiles of free and adsorbed HRP are similar. For ?-CT, larger activation volumes are found in the adsorbed state. However, up to about 500 bar, the enzymatic reaction of ?-CT, which is adsorbed on silica particles, is characterized by a negative activation volume. This observation suggests that application of pressure might indeed be useful to enhance the activity of enzymes on carrier particles. PMID:25479476

Schuabb, Vitor; Czeslik, Claus

2014-12-30

386

POULTRY MANURE-BASED ACTIVATED CARBONS AS MERCURY ADSORBENTS  

Science.gov (United States)

Increased emphasis on reduction of mercury emissions from coal fired electric power plans have resulted in environmental regulations that may in the future require application of activated carbons as mercury sorbents. The sorbents could be injected into the flue gas stream where is adsorbs the merc...

387

Adsorption of iodine by silver-impregnated hydrophobic adsorbent  

International Nuclear Information System (INIS)

Hydrophobic adsorbents, which consist of porous styrene-divinylbenzene copolymer (SDB) impregnated with silver, were developed for the removal of iodine from the dissolver off-gas (DOG). The adsorption of iodine in a simulated off-gas including iodine, NOx and water vapor was examined by use of an adsorption column packed with the hydrophobic adsorbents. Silver impregnation methods using organic solutions were proposed. By use of dioxan and butylamine, which can swell the SDB easily, silver nitrate and metallic silver were uniformly distributed in the SDB particles. The breakthrough of iodine was not influenced by the presence of NOx and water vapor. For a macroporous SDB with the pore volume of 1.59 ml/g-SDB and the average pore diameter of 500A, impregnated with metallic silver at silver content of 28 wt%, a high adsorption capacity of 0.14g-I2/cm3-adsorbent was obtained, compared to that of a commercial adsorbent. AgNO3-impregnated silica gel. The impregnated silver was utilized about 91% for the iodine adsorption. (author)

388

SYNTHETIC RESIN ADSORBENTS IN TREATMENT OF INDUSTRIAL WASTE STREAMS  

Science.gov (United States)

The use of synthetic polymeric adsorbents for removal of organic pollutants from industrial waste streams is a viable alternative to more common treatment methods such as carbon adsorption. However, resin technology is not widely practiced due to the difficulty of selecting the a...

389

Interactions of organic contaminants with mineral-adsorbed surfactants  

Science.gov (United States)

Sorption of organic contaminants (phenol, p-nitrophenol, and naphthalene) to natural solids (soils and bentonite) with and without myristylpyridinium bromide (MPB) cationic surfactant was studied to provide novel insight to interactions of contaminants with the mineral-adsorbed surfactant. Contaminant sorption coefficients with mineral-adsorbed surfactants, Kss, show a strong dependence on surfactant loading in the solid. At low surfactant levels, the Kss values increased with increasing sorbed surfactant mass, reached a maximum, and then decreased with increasing surfactant loading. The Kss values for contaminants were always higher than respective partition coefficients with surfactant micelles (Kmc) and natural organic matter (Koc). At examined MPB concentrations in water the three organic contaminants showed little solubility enhancement by MPB. At low sorbed-surfactant levels, the resulting mineral-adsorbed surfactant via the cation-exchange process appears to form a thin organic film, which effectively "adsorbs" the contaminants, resulting in very high Kss values. At high surfactant levels, the sorbed surfactant on minerals appears to form a bulklike medium that behaves essentially as a partition phase (rather than an adsorptive surface), with the resulting Kss being significantly decreased and less dependent on the MPB loading. The results provide a reference to the use of surfactants for remediation of contaminated soils/sediments or groundwater in engineered surfactant-enhanced washing.

Zhu, L.; Chen, B.; Tao, S.; Chiou, C.T.

2003-01-01

390

Organobentonites as multifunctional adsorbents of organic and inorganic water pollutants  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of this study was to find a low cost, easy to synthesize and efficient adsorbent for the simultaneous adsorption of both organic and inorganic pollutants (including textile dyes, toxic metals etc.. The starting material, domestic bentonite clay from Bogovina was modified with amounts of hexadecyltrimethylammonium cations corresponding to 0.5 and 1.0 times of the value of the cation exchange capacity value. The organobentonites were tested as adsorbents in a three-dye-containing solution, a three-component solution of Pb2+, Cd2+ and Ni2+ and a hexa- component solution containing all investigated dyes and toxic metal cations. The used adsorbents showed the highest affinity toward Acid Yellow 99 and Ni2+ ions. Dye adsorption was enhanced in the presence of toxic metal cations, while the adsorption of all toxic cations from the hexa-component solution was lower than from the three-component solution containing only toxic cations. The synthesized hexadecyltrimethylammonium bentonite could be regarded as an efficient multifunctional adsorbent for the investigated type of water pollutants.

Jovi?-Jovi?i? Nat?ša

2014-01-01

391

Experimental studies of surface-adsorbate interactions and surface magnetism  

International Nuclear Information System (INIS)

Surface Magnetism and surface-adsorbate interactions were investigated using Reflection Adsorption InfraRed Spectroscopy (RAIRS) and Spin Polarised Spectroscopy (SPS). RAIRS was used to study the adsorption of Cr(CO)6 and CO on Pd (100). The thermally induced decomposition of Cr(CO)6 was seen on the Pd (100) surface. The adsorbed fragments after decomposition had a visible affect on subsequently adsorbed Cr(CO)6. Detailed lineshape analysis of the IR absorption spectra of CO adsorption at cryogenic temperatures was undertaken. The lineshape of the CO stretch can be explained by the formation of three phases of chemisorbed CO, containing both upright and tilted CO molecules with respect to the surface plane. At cryogenic temperatures below 45 K CO physisorbs above the chemisorbed layer, allowing the affects of physisorbed overlayers to be investigated. SPS was used to study the phenomenon of adsorbate induced rotation of the easy axis of magnetisation of stepped Co/Cu (100) thin films. The 1 eV secondary electron polarisation was measured to allow the observation of the O2 induced switching of the easy axis. Spin resolved photoemission spectra were produced and revealed the polarisation of the Co 3d and Cu valence band, as well as the adsorbed oxygen 2p orbital. The results show an enhanced polarisation of the Cu and O 2p bands due to a spin dependent inelastic mean free path of the Co film. A Spin Polarised Auger Electron Spo film. A Spin Polarised Auger Electron Spectroscopy (SPAES) system was developed at Daresbury Laboratory. The effectiveness of using faster amplifiers with the normal electronics of the compact Mott polarimeter was investigated. The results were promising and produced a measurement of the polarisation of Auger electrons from a Fe86B14 amorphous ribbon. (author)

392

Natural material adsorbed onto a polymer to enhance immune function  

Directory of Open Access Journals (Sweden)

Full Text Available Ana Paula Barcelos Reinaque,1 Eduardo Luzía França,2 Edson Fredulin Scherer,3 Mayra Aparecida Côrtes,1 Francisco José Dutra Souto,4 Adenilda Cristina Honorio-França51Post Graduate Program in Material Science, 2Institute of Biological and Health Science, Federal University of Mato Grosso, Barra do Garças, 3Post Graduate Program in Material Science, Institute of Biological and Health Science, Federal University of Mato Grosso, Pontal do Araguaia, 4Faculty of Medical Sciences, Federal University of Mato Grosso, Cuiabá, 5Institute of Biological and Health Science, Federal University of Mato Grosso, Pontal do Araguaia, MT, BrazilBackground: In this study, we produced poly(ethylene glycol (PEG microspheres of different sizes and adsorbing a medicinal plant mixture, and verified their effect in vitro on the viability, superoxide production, and bactericidal activity of phagocytes in the blood.Methods: The medicinal plant mixture was adsorbed onto PEG microspheres and its effects were evaluated by flow cytometry and fluorescence microscopy.Results: Adsorption of the herbal mixture onto the PEG microspheres was achieved and the particles were internalized by phagocytes. PEG microspheres bearing the adsorbed herbal mixture stimulated superoxide release, and activated scavenging and microbicidal activity in phagocytes. No differences in functional activity were observed when the phagocytes were not incubated with PEG microspheres bearing the adsorbed herbal mixture.Conclusion: This system may be useful for the delivery of a variety of medicinal plants and can confer additional protection against infection. The data reported here suggest that a polymer adsorbed with a natural product is a treatment alternative for enhancing immune function.Keywords: natural product, polymer, adsorption, immune function, phagocytes

Reinaque AP

2012-08-01

393

Adsorbate structures and catalytic reactions studied in the torrpressure range by scanning tunneling microscopy  

Energy Technology Data Exchange (ETDEWEB)

High-pressure, high-temperature scanning tunneling microscopy (HPHTSTM) was used to study adsorbate structures and reactions on single crystal model catalytic systems. Studies of the automobile catalytic converter reaction [CO + NO {yields} 1/2 N{sub 2} + CO{sub 2}] on Rh(111) and ethylene hydrogenation [C{sub 2}H{sub 4} + H{sub 2} {yields} C{sub 2}H{sub 6}] on Rh(111) and Pt(111) elucidated information on adsorbate structures in equilibrium with high-pressure gas and the relationship of atomic and molecular mobility to chemistry. STM studies of NO on Rh(111) showed that adsorbed NO forms two high-pressure structures, with the phase transformation from the (2 x 2) structure to the (3 x 3) structure occurring at 0.03 Torr. The (3 x 3) structure only exists when the surface is in equilibrium with the gas phase. The heat of adsorption of this new structure was determined by measuring the pressures and temperatures at which both (2 x 2) and (3 x 3) structures coexisted. The energy barrier between the two structures was calculated by observing the time necessary for the phase transformation to take place. High-pressure STM studies of the coadsorption of CO and NO on Rh(111) showed that CO and NO form a mixed (2 x 2) structure at low NO partial pressures. By comparing surface and gas compositions, the adsorption energy difference between topsite CO and NO was calculated. Occasionally there is exchange between top-site CO and NO, for which we have described a mechanism for. At high NO partial pressures, NO segregates into islands, where the phase transformation to the (3 x 3) structure occurs. The reaction of CO and NO on Rh(111) was monitored by mass spectrometry (MS) and HPHTSTM. From MS studies the apparent activation energy of the catalytic converter reaction was calculated and compared to theory. STM showed that under high-temperature reaction conditions, surface metal atoms become mobile. Ethylene hydrogenation and its poisoning by CO was also studied by STM on Rh(111) and Pt(111). Poisoning was found to coincide with decreased adsorbate mobility. Under ethylene hydrogenation conditions, no order is detected by STM at 300 K, as hydrogen and ethylidyne, the surface species formed by gas-phase ethylene, are too mobile. When CO is introduced, the reaction stops, and ordered structures appear on the surface. For Rh(111), the structure is predominantly a mixed c(4 x 2), though there are some areas of (2 x 2). For Pt(111), the structure is hexagonal and resembles the Moire pattern seen when Pt(111) is exposed to pure CO. From these studies it is concluded that CO poisons by stopping adsorbate mobility. This lack of adsorbate mobility prevents the adsorption of ethylene from the gas phase by hindering the creation of adsorption sites.

Hwang, Kevin Shao-Lin

2003-05-23

394

Layered double hydroxide-based nanomaterials as highly efficient catalysts and adsorbents.  

Science.gov (United States)

Layered double hydroxides (LDHs) are a class of anion clays consisting of brucite-like host layers and interlayer anions, which have attracted increasing interest in the fields of catalysis/adsorption. By virtue of the versatility in composition, morphology, and architecture of LDH materials, as well as their unique structural properties (intercalation, topological transformation, and self-assembly with other functional materials), LDHs display great potential in the design and fabrication of nanomaterials applied in photocatalysis, heterogeneous catalysis, and adsorption/separation processes. Taking advantage of the structural merits and various control synthesis strategies of LDHs, the active center structure (e.g., crystal facets, defects, geometric and electronic states, etc.) and macro-nano morphology can be facilely manipulated for specific catalytic/adsorbent processes with largely enhanced performances. In this review, the latest advancements in the design and preparation of LDH-based functional nanomaterials for sustainable development in catalysis and adsorption are summarized. PMID:25137218

Li, Changming; Wei, Min; Evans, David G; Duan, Xue

2014-11-01

395

Increasing the sorption activity of carbon adsorbents by electron-beam processing and fullerene microadditives  

Science.gov (United States)

The sorption capacity of activated carbon with respect to Cu2+ cations was found to be enhanced considerably upon its chemical modification with fullerenes and during its electron-beam processing. It was discovered that introducing fullerenes (20 ?g/g) into activated carbon leads to a change in the chemical composition of its surface, due to changes in the system of conjugated bonds in activated carbon leading to an increase in the content of Brønsted acid (p K a 0-5) and weakly base (p K a 8-11) sites capable of cation exchange on the material surface. We conclude that electron-beam processing (optimal dose, 25-50 kGy) facilitates the rearrangement of bonds on the surface of activated carbon, thereby increasing the number of Lewis base and Brønsted acid sites capable of adsorbing metal ions in accordance with the donor-acceptor and cation-exchange mechanism, respectively.

Myakin, S. V.; Nikonova, V. Yu.; Korsakov, V. G.; Samonin, V. V.

2011-09-01

396

Biodegradation of medium chain hydrocarbons by Acinetobacter venetianus 2AW immobilized to hair-based adsorbent mats.  

Science.gov (United States)

The natural attenuation of hydrocarbons can be hindered by their rapid dispersion in the environment and limited contact with bacteria capable of oxidizing hydrocarbons. A functionalized composite material is described herein, that combines in situ immobilized alkane-degrading bacteria with an adsorbent material that collects hydrocarbon substrates, and facilitates biodegradation by the immobilized bacterial population. Acinetobacter venetianus 2AW was isolated for its ability to utilize hydrophobic n-alkanes (C10-C18) as the sole carbon and energy source. Growth of strain 2AW also resulted in the production of a biosurfactant that aided in the dispersion of complex mixtures of hydrophobic compounds. Effective immobilization of strain 2AW to the surface of Ottimat™ adsorbent hair mats via vapor phase deposition of silica provided a stable and reproducible biocatalyst population that facilitates in situ biodegradation of n-alkanes. Silica-immobilized strain 2AW demonstrated ca. 85% removal of 1% (v/v) tetradecane and hexadecane within 24 h, under continuous flow conditions. The methodology for immobilizing whole bacterial cells at the surface of an adsorbent, for in situ degradation of hydrocarbons, has practical application in the bioremediation of oil in water emulsions. Published 2011 American Institute of Chemical Engineers Biotechnol Prog., 2011. PMID:21948333

Luckarift, Heather R; Sizemore, Susan R; Farrington, Karen E; Fulmer, Preston A; Biffinger, Justin C; Nadeau, Lloyd J; Johnson, Glenn R

2011-01-01

397

Removal of alizarin red S (dye) from aqueous media by using alumina as an adsorbent  

International Nuclear Information System (INIS)

Adsorption is potentially an attractive methodology for removing hazardous dyestuff and heavy metals from industrial effluents. In this work the removing efficiency of an industrially important dye Alizarin Red S from aqueous media using alumina as adsorbent has been investigated. Various parameters, which can influence the adsorption like, mesh size of adsorbent, contact time of solution with adsorbent, temperature, pH, adsorbent dose and stirring speed were optimized. (author)

398

Electronic and vibrational excitations in adsorbed metalorganic molecules  

International Nuclear Information System (INIS)

HREELS has been used to probe the vibrational and electronic properties of metalorganic molecules adsorbed on III-V semiconductor surfaces. Following adsorbate characterisation, the HREELS electron beam is used to investigate possible resonant vibrational excitation for a range of alkyl-based molecules adsorbed on GaAs(100) and InSb(100). By varying the electron beam energy of the HREEL spectrometer, resonant vibrational excitation is demonstrated at discrete energies in all the molecules studied. This excitation mechanism is confirmed by obtaining adsorbate excitation functions, the observation of enhanced overtone and combination bands at the resonant energies, the measurement of angular distributions that are not consistent with dipole scattering, and by comparison of reflectivity measurements from both the clean and adsorbate covered surfaces. Resonant vibrational excitation is strong in the methyl-based molecules studied (Me3Al and Me3In), but even higher resonant cross-sections are evident in the larger alkyl-based metalorganics (Et3Ga and Np3Ga). The resonant behaviour is generally independent of substrate, although electronic excitation of the InSb(100) surface appears to prevent higher energy resonances (>10 eV) being observed for the methyl-based molecules. The incident HREELS electron beam causes dissociation of Me3Al and Me3In adsorbed on either surface, with a threshold energy of ? 10 eV;ace, with a threshold energy of ? 10 eV; an energy close to the ionisation potential of the molecules. An electron impact ionisation dissociation mechanism is inferred, with chemisorbed Me groups decomposing to surface CH2 species. Electron induced dissociation rarely occurs for molecules chemisorbed on metal surfaces due to the efficient quenching of the excited states on these substrates. No dissociation is observed for Et3Ga or NP3Ga, even above their ionisation potential. It is suggested that the time taken to form stable species in these larger compounds following ionisation is much longer than the quenching time and decomposition cannot occur. (author)

399

Dynamic separation of Szilard-Chalmers reaction products applied to the trioxalatochromium ion adsorbed on anionic exchange resin  

International Nuclear Information System (INIS)

A method of dynamic elution of recoiled 51Cr+3, formed by the Szilard-Chalmers reaction during the irradiation of trioxalatochromium ion adsorbed on anionic exchange resin is presented. The influence of some factors on the separation yield of chromium-51, such as: composition, concentration and flow rate of eluent, mesh size of the resin and irradiation time are studied. The results are compardd with those obtained by the static method, in which the recoiled atom is separated from the target after irradiation. Because of the high separation yield of chromium-51, the method of dynamic separation is proposed for routine production of this elemnt, with high specific activities. (author)

400

Preparation of core-shell Fe3O4/SiO2 microspheres as adsorbents for purification of DNA  

International Nuclear Information System (INIS)

Nearly monodisperse core-shell Fe3O4/SiO2 microspheres have been prepared via a glycol reduction method followed by a modified Stoeber process. The thickness of the silica shells can be tuned in the range 33-53 nm by varying the amount of tetraethyl silicate (TEOS) during syntheses. The magnetic composite microspheres were characterized with XRD, XPS, FTIR, TEM, ICP-OES and VSM, and further tested as adsorbents for purification of plasmid DNA from Escherichia coli DH5? cells. The magnetic purification of plasmid DNA leads to satisfying integrity, yield and purity in comparison with those isolated by the traditional phenol-chloroform extraction.

401

Dirac point resonances due to atoms and molecules adsorbed on graphene and transport gaps and conductance quantization in graphene nanoribbons with covalently bonded adsorbates  

OpenAIRE

We present a tight binding theory of the Dirac point resonances due to adsorbed atoms and molecules on an infinite 2D graphene sheet based on the standard tight binding model of the graphene p-band electronic structure and the extended Huckel model of the adsorbate and nearby graphene carbon atoms. The relaxed atomic geometries of the adsorbates and graphene are calculated using density functional theory. Our model includes the effects of the local rehybridization of the gra...

Ihnatsenka, S.; Kirczenow, G.

2010-01-01

402

Evaluation of Adsorption Properties for Cs and Sr Selective Adsorbents-13171  

Energy Technology Data Exchange (ETDEWEB)

The development of effective treatment and disposal methods is very urgent and important subject. Tohoku University and UNION SHOWA have developed various selective adsorbents (zeolites, zeolite sheets and composites loaded with insoluble ferrocyanides) for the effective decontamination of radioactive Cs{sup +} and Sr{sup 2+} As for Cs{sup +} adsorption, CST, chabazite and insoluble ferrocyanides composites had relatively large distribution coefficients (K{sub d}) above 10{sup 3} cm{sup 3}/g and excellent adsorption kinetics in seawater. Even after high temperature calcination at 1,100 deg. C, cesium was still immobilized in the calcined products of Cs{sup +}-zeolites, suggesting high immobilization ability of zeolites for Cs{sup +}. As for Sr{sup 2+} adsorption, A and X zeolites had relatively large K{sub d} values around 10{sup 2} cm{sup 3}/g, and zeolite sheet (A zeolite) exhibited excellent adsorption kinetics in seawater. Considering the decontamination of radioactive Sr{sup 2+} in groundwater, the effects of Ca{sup 2+} and Mg{sup 2+} ions on the K{sub d} value of Sr{sup 2+} were further examined by batch method. The K{sub d} value of Sr{sup 2+} was almost independent of Mg{sup 2+} concentration up to 2,500 ppm, while gradually lowered in the presence of Ca{sup 2+} above 200 ppm, due to the differences in the ionic radius of hydrated ion. The Cs{sup +} and Sr{sup 2+} adsorption ability for KNiFC-A (composite of A zeolite loaded with insoluble ferrocyanides) was examined by batch method. Here the matrix of composite (A zeolite) and loaded ferrocyanides (KNiFC) have high selectivity towards Sr{sup 2+} and Cs{sup +}, respectively. The K{sub d} values of Sr{sup 2+} and Cs{sup +} in seawater were estimated to be above 10{sup 2} and 10{sup 3} cm{sup 3}/g, respectively, indicating the effectiveness for the decontamination of both Sr{sup 2+} and Cs{sup +}. The basic data on the Cs{sup +} and Sr{sup 2+} adsorption properties for selective adsorbents are effective for the practical decontamination processes of these metal ions in seawater and groundwater. (authors)

Nakai, Tomonori; Wakabayashi, Syunya; Mimura, Hitoshi; Niibori, Yuichi; Kurosaki, Fumio; Matsukura, Minoru [Dept. of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University,Aramaki-Aza-Aoba 6-6-01-2,Sendai, 980-8579 (Japan); Tanigawa, Hiroshi; Ishizaki, Eiji [UNION SHOWA K.K., 17-20, Mita 2-chome, Minato-ku, Tokyo 108-0073 (Japan)

2013-07-01

403

Stretching of a chain polymer adsorbed at a surface  

CERN Document Server

In this paper we present simulations of a surface-adsorbed polymer subject to an elongation force. The polymer is modelled by a self-avoiding walk on a regular lattice. It is confined to a half-space by an adsorbing surface with attractions for every vertex of the walk visiting the surface, and the last vertex is pulled perpendicular to the surface by a force. Using the recently proposed flatPERM algorithm, we calculate the phase diagram for a vast range of temperatures and forces. The strength of this algorithm is that it computes the complete density of states from one single simulation. We simulate systems of sizes up to 256 steps.

Krawczyk, J; Rechnitzer, A; Owczarek, A L

2004-01-01

404

Adsorption studies of radon and xenon on different adsorbents  

International Nuclear Information System (INIS)

Liquid noble gas detectors play a leading role for direct detection dark matter experiments. Particularly xenon with its high mass and the absence of radioactive isotopes is well suited as target material and used in the XENON project. To reduce background the detector of the next generation, the XENON1T detector, is planned to be operated with a dynamic, adsorption based purification system to clean the xenon from radon contamination. In the first part of this bachelor thesis, radon adsorption in presence of xenon was analyzed for different adsorbent samples, to find the best suited material for the radon removal system. In total one metal organic framework and two zeolites were tested. The second part of the thesis describes measurements of xenon adsorption isotherms on an activated carbon sample at different temperatures. These measurements should help to answer questions concerning the amount and type of adsorbent required to operate successfully the radon removal system planed for the XENON1T experiment.

405

Carbon Modified Silica based Adsorbent for Potential Application  

International Nuclear Information System (INIS)

The carbon modified silica adsorbents were prepared by synthesizing and modifying zeolite Y type with activated carbon. This paper reports on effects of activated carbon loadings on the methane and nitrogen adsorption, structure and properties of carbon modified zeolite Y. With the increase in activated carbon loadings, the surface area, pore size and pore volume of the activated carbon loaded zeolite Y adsorbent decreased. The intensity of the diffraction patterns of zeolite Y decreased after the activated carbon was loaded. With increasing activated carbon loadings, the intensity of diffraction peaks decreased. Adsorption capacity of nitrogen (N2) was smaller than adsorption capacity of methane (CH4) by using activated carbon modified silica. When activated carbon loadings 30% wt.%, adsorption capacity of methane and nitrogen was 12.9317 wt.% and 12.6115 wt.%, these were caused by difference in molecular weight. The molecular weight of nitrogen is bigger than molecular weight of methane

406

Neutron diffraction and inelastic scattering from adsorbed molecules  

International Nuclear Information System (INIS)

Neutron scattering measurements on the structure and dynamics of adsorbed phases at the gas solid interface have proliferated in the last five years and this paper reports some recently obtained results for the systems methane-graphite and ammonia-graphite, which show BET type I and type III isotherms respectively. These systems clearly illustrate the differences in both structure and dynamics to be expected in other examples where either wetting of the surface or non-wetting behaviour occurs upon adsorption. Evidence for phase transitions in both types of system coming from diffraction is reported, and this is substantiated by measurements using inelastic scattering to follow the molecular dynamics. The neutron inelastic scattering from molecules adsorbed on platinum black and in zeolites reveals some of the virtues of neutron inelastic scattering for the study of chemisorbed species. Finally, some preliminary experiments on neutron small angle scattering at the solid liquid interface in polystyrene latex-water sols are reported. (Auth.)

407

Electron bombardment of water adsorbed on Zr(0001) surfaces  

CERN Document Server

A study of the effects of electron bombardment on water adsorbed on Zr(0001) is reported. Zirconium surfaces are dosed with isotopic water mixtures at 160 K followed by electron bombardment (485 eV). The system is then probed by low energy electron diffraction, temperature programmed desorption (TPD) and Auger electron spectroscopy (AES). No evidence is found that would indicate preferential mixing of hydrogen from the bulk with isotopic water dissociation products during TPD. However, electron bombardment results in the sharpening of a hydrogen/deuterium desorption peak near 320 K and the production of water near 730 K at low water exposures. In addition, although water does not oxidize Zr(0001) thermally, electron bombardment of adsorbed water induces a shift of about 2 eV in the Zr AES features indicating that the surface is partially oxidized by electron bombardment.

Ankrah, S; Ramsier, R D

2003-01-01

408

Radiolysis of alanine adsorbed in a clay mineral  

International Nuclear Information System (INIS)

Optical activity in molecules is a chemical characteristic of living beings. In this work, we examine the hypothesis of the influence of different mineral surfaces on the development of a specific chirality in organic molecules when subjected to conditions simulating the primitive Earth during the period of chemical evolution. By using X-ray diffraction techniques and HPLC/ELSD to analyze aqueous suspensions of amino acids adsorbed on minerals irradiated in different doses with a cobalt-60 gamma source, the experiments attempt to prove the hypothesis that some solid surfaces (like clays and meteorite rocks) may have a concentration capacity and protective role against external sources of ionizing radiation (specifically ?-ray) for some organic compounds (like some amino acids) adsorbed on them. Preliminary results show a slight difference in the adsorption and radiolysis of the D-and L-alanine

409

Adsorbed monolayers on suspended single-walled carbon nanotubes  

Science.gov (United States)

A monolayer of adsorbates on a single-walled carbon nanotube presents the possibility of extending earlier studies of two-dimensional monolayer systems on graphite to the quasi-one-dimensional regime, by effectively imposing cylindrical boundary conditions. The monolayer can be detected either via its effect on the nanotube's conductance or by using the nanotube itself as a vibrating microbalance. Many adsorbates are known to affect the conductance, through a variety of mechanisms. Amongst these are O2 and the noble gases Xe and Kr, whose phases and ordering on 2D graphite are well known. Our experiments so far have indicated that the presence of an O2 layer on a nanotube close to liquid nitrogen temperatures can be detected using a threshold shift. We are now fabricating individual suspended nanotube devices with the initial aim of studying cylindrical commensurability effects on the phases of noble gases using the microbalance technique.

Wang, Zenghui; Wei, Jiang; Dormaier, Robert; Vilches, Oscar; Cobden, David

2006-03-01

410

Photodissociation of iron pentacarbonyl adsorbed on Ag(111)  

International Nuclear Information System (INIS)

The adsorption states and photochemistry of Fe(CO)5 adsorbed on Ag(111) surface at ?90 K were studied using IR reflection absorption spectroscopy (IRAS) and thermal desorption spectroscopy (TDS). Fe(CO)5 is molecularly adsorbed on the surface and desorbed around 180 K. A totally symmetric vibrational band appears at 2114 cm-1 in the IRA spectrum, indicating that structural deformation of Fe(CO)5 or charge transfer between the substrate and the adsorbate occurs to some extent upon adsorption. Irradiation of the adsorbed Fe(CO)5 leads to decarbonylation with a high quantum yield, especially around 330 nm. This enhanced photodecomposition is attributable to resonant coupling with excited surface plasmon of Ag. Effect of the surface plasmon on the photodecarbonylation yield was measured as a function of the absorption amount of n-decane preadsorbed on the surface as a spacer layer. The yield was increased with increasing n-decane layer, maximized at around two monolayers, and then decreased to a value twice as large as the initial yield after n-decane coverage is over three monolayers. This result implies that Fe(CO)5 molecules near the surface undergo significant quenching of photoexcited states, and the surface-plasmon induced enhancement lies within ca. 1 nm apart from the surface. The final photo-product exhibits two sharp C-O stretching bands at 2058 and 2068 cm-1 in IRA spectrum, which arm-1 in IRA spectrum, which are assigned to the species produced from the first layer and the overlayer Fe(CO)5, respectively. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

411

Mercury(II) Removal with Modified Magnetic Chitosan Adsorbents  

OpenAIRE

Two modified chitosan derivatives were prepared in order to compare their adsorption properties for Hg(II) removal from aqueous solutions. The one chitosan adsorbent (CS) is only cross–linked with glutaraldehyde, while the other (CSm), which is magnetic, is cross-linked with glutaraldehyde and functionalized with magnetic nanoparticles (Fe3O4). Many possible interactions between materials and Hg(II) were observed after adsorption and explained via characterization with various techniques (S...

Kyzas, George Z.; Deliyanni, Eleni A.

2013-01-01