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1

Rechargeable Na/Na0.44MnO2 cells with ionic liquid electrolytes containing various sodium solutes  

NASA Astrophysics Data System (ADS)

Orthorhombic Na0.44MnO2 with wide structural tunnels for sodium ion transport is synthesized. Butylmethylpyrrolidinium-bis(trifluoromethanesulfonyl)imide (BMP-TFSI) ionic liquid (IL) with various Na solutes, namely NaBF4, NaClO4, NaTFSI, and NaPF6, is used as an electrolyte for rechargeable Na/Na0.44MnO2 cells. The cell with NaClO4-incorporated IL electrolyte exhibits superior charge-discharge performance due to it having the lowest solid-electrolyte-interface resistance and charge transfer resistance at both the Na and Na0.44MnO2 electrodes. The IL electrolyte shows high thermal stability and is suitable for use at an elevated temperature. At 75 °C, the measured capacity of Na0.44MnO2 in the IL electrolyte with NaClO4 is as high as 115 mAh g-1 (at 0.05 C), which is close to the theoretical value (121 mAh g-1). Moreover, 85% of this capacity can be retained when the charge-discharge rate is increased to 1 C. These properties are superior to those of a conventional organic electrolyte.

Wang, Chueh-Han; Yeh, Yu-Wen; Wongittharom, Nithinai; Wang, Yi-Chen; Tseng, Chung-Jen; Lee, Sheng-Wei; Chang, Wen-Sheng; Chang, Jeng-Kuei

2015-01-01

2

Sorption of lead (II), cobalt (II) and copper (II) ions from aqueous solutions by ?-MnO2 nanostructure  

NASA Astrophysics Data System (ADS)

Manganese dioxide ?-MnO2 was synthesized via the reduction–oxidation reaction between KMnO4 and C2H5OH at room temperature and characterized with x-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer–Emmet–Teller nitrogen adsorption (BET–N2 adsorption). The results showed that ?-MnO2 was about 10–18 nm in size and the BET surface area was about 65 m2 g?1. The feasibility of ?-MnO2 used as a low cost adsorbent for the adsorption of Pb(II), Co(II) and Cu(II) from aqueous solutions was explored. During the adsorption process, batch technique was used, and the effects of contact time and pH on adsorption efficiency under room temperature were studied. The adsorption data showed that the Freundlich, Langmuir and Redlich-Peterson isotherms are a good model for the sorption of Co(II) and Cu(II), while the Langmuir and Redlich–Peterson isotherms provide a reasonable fit to the experimental data for Pb(II). By using the Langmuir isotherm, the adsorption capacities for Pb(II), Co(II) and Cu(II) are found to be 200 mg g?1, 90.91 mg g?1 and 83.33 mg g?1, respectively. The effectiveness of ?-MnO2 in the sorption of the three metal ions from aqueous system has the order Pb(II) > Co(II) > Cu(II). Kinetic studies showed that a pseudo-second-order model was more suitable than the pseudo-first-order model. Also, the intra-particle diffusion models were used to ascertain the mechanism of the sorption process. It is concluded that ?-MnO2 can be used as an effective adsorbent for removing Pb(II), Co(II) and Cu(II) from aqueous solutions.

Chung Le, Ngoc; Van Phuc, Dinh

2015-01-01

3

Preparation and adsorption performance of MnO2/PAC composite towards aqueous glyphosate.  

PubMed

Glyphosate (N-phosphonomethylglycine (PMG)) is the organophosphate herbicide most widely used in the world, and industrial production of PMG generates large quantities of wastewater. A manganese dioxide-coated powdered activated carbon (MnO2/PAC) composite was synthesized and investigated for the adsorption of PMG from wastewater. The results of scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectrometry (EDAX) revealed that MnO2 was formed on the surface of the carbon during the modification process. Batch adsorption results showed that the optimal pH for glyphosate adsorption on MnO2/PAC was 3.0. In the range 0.01(-1) molL(-1), glyphosate removal by MnO2/PAC decreased with an increase in ionic strength. Among the coexistent anions, only phosphate showed significant inhibition of PMG removal due to competitive complexation. Batch studies revealed that MnO2/PAC could reach a maximum PMG adsorption capacity of 283 mg g(-1). The Langmuir equilibrium model was found to be suitable for describing PMG sorption, and kinetic studies revealed that adsorption followed second-order rate kinetics. It was also proved that the adsorbed PMG could be effectively desorbed from MnO2/PAC in 1.0 molL(-1) NaOH. All of these results implied that the MnO2/PAC composite may be used as an effective adsorbent for recycling PMG from wastewater. PMID:23240199

Cui, Hao; Li, Qin; Qian, Yan; Zhang, Qiu; Zhai, Jianping

2012-09-01

4

Predicting the electrochemical properties of MnO2 nanomaterials used in rechargeable li batteries: simulating nanostructure at the atomistic level.  

PubMed

Nanoporous beta-MnO2 can act as a host lattice for the insertion and deinsertion of Li with application in rechargeable lithium batteries. We predict that, to maximize its electrochemical properties, the beta-MnO2 host should be symmetrically porous and heavily twinned. In addition, we predict that there exists a "critical (wall) thickness" for MnO2 nanomaterials above which the strain associated with Li insertion is accommodated via a plastic, rather than elastic, deformation of the host lattice leading to property fading upon cycling. We predict that this critical thickness lies between 10 and 100 nm for beta-MnO2 and is greater than 100 nm for alpha-MnO2: the latter accommodates 2 x 2 tunnels compared with the smaller 1 x 1 tunnels found in beta-MnO2. This prediction may help explain why certain (nano)forms of MnO2 are electrochemically active, while others are not. Our predictions are based upon atomistic models of beta-MnO2 nanomaterials. In particular, a systematic strategy, analogous to methods widely and routinely used to model crystal structure, was used to generate the nanostructures. Specifically, the (space) symmetry associated with the nanostructure coupled with basis nanoparticles was used to prescribe full atomistic models of nanoparticles (0D), nanorods (1D), nanosheets (2D), and nanoporous (3D) architectures. For the latter, under MD simulation, the amorphous nanoparticles agglomerate together with their periodic neighbors to formulate the walls of the nanomaterial; the particular polymorphic structure was evolved using simulated amorphization and crystallization. We show that our atomistic models are in accord with experiment. Our models reveal that the periodic framework architecture, together with microtwinning, enables insertion of Li anywhere on the (internal) surface and facilitates Li transport in all three spatial directions within the host lattice. Accordingly, the symmetrically porous MnO2 can expand and contract linearly and crucially elastically under charge/discharge. We also suggest tentatively that our predictions for MnO2 are more general in that similar arguments may apply to other nanomaterials, which might expand and contract elastically upon charging/discharging. PMID:19206514

Sayle, Thi X T; Maphanga, R Rapela; Ngoepe, Phuti E; Sayle, Dean C

2009-05-01

5

Fe3O4 and MnO2 assembled on honeycomb briquette cinders (HBC) for arsenic removal from aqueous solutions.  

PubMed

In this study, a novel composite adsorbent (HBC-Fe3O4-MnO2) was synthesized by combining honeycomb briquette cinders (HBC) with Fe3O4 and MnO2 through a co-precipitation process. The purpose was to make the best use of the oxidative property of MnO2 and the adsorptive ability of magnetic Fe3O4 for enhanced As(III) and As(V) removal from aqueous solutions. Experimental results showed that the adsorption capacity of As(III) was observed to be much higher than As(V). The maximum adsorption capacity (2.16mg/g) was achieved for As(III) by using HBC-Fe3O4-MnO2 (3:2) as compared to HBC-Fe3O4-MnO2 (2:1) and HBC-Fe3O4-MnO2 (1:1). The experimental data of As(V) adsorption fitted well with the Langmuir isotherm model, whereas As(III) data was described perfectly by Freundlich model. The pseudo-second-order kinetic model was fitted well for the entire adsorption process of As(III) and As(V) suggesting that the adsorption is a rate-controlling step. Aqueous solution pH was found to greatly affect the adsorption behavior. Furthermore, co-ions including HCO3(-) and PO4(3-) exhibited greater influence on arsenic removal efficiency, whereas Cl(-), NO3(-), SO4(2-) were found to have negligible effects on arsenic removal. Five consecutive adsorption-regeneration cycles confirmed that the adsorbent could be reusable for successive arsenic treatment and can be used in real treatment applications. PMID:25585269

Zhu, Jin; Baig, Shams Ali; Sheng, Tiantian; Lou, Zimo; Wang, Zhuoxing; Xu, Xinhua

2015-04-01

6

Ti-substituted tunnel-type Na0.44MnO2 oxide as a negative electrode for aqueous sodium-ion batteries.  

PubMed

The aqueous sodium-ion battery system is a safe and low-cost solution for large-scale energy storage, because of the abundance of sodium and inexpensive aqueous electrolytes. Although several positive electrode materials, for example, Na0.44MnO2, were proposed, few negative electrode materials, for example, activated carbon and NaTi2(PO4)3, are available. Here we show that Ti-substituted Na0.44MnO2 (Na0.44[Mn1-xTix]O2) with tunnel structure can be used as a negative electrode material for aqueous sodium-ion batteries. This material exhibits superior cyclability even without the special treatment of oxygen removal from the aqueous solution. Atomic-scale characterizations based on spherical aberration-corrected electron microscopy and ab initio calculations are utilized to accurately identify the Ti substitution sites and sodium storage mechanism. Ti substitution tunes the charge ordering property and reaction pathway, significantly smoothing the discharge/charge profiles and lowering the storage voltage. Both the fundamental understanding and practical demonstrations suggest that Na0.44[Mn1-xTix]O2 is a promising negative electrode material for aqueous sodium-ion batteries. PMID:25806965

Wang, Yuesheng; Liu, Jue; Lee, Byungju; Qiao, Ruimin; Yang, Zhenzhong; Xu, Shuyin; Yu, Xiqian; Gu, Lin; Hu, Yong-Sheng; Yang, Wanli; Kang, Kisuk; Li, Hong; Yang, Xiao-Qing; Chen, Liquan; Huang, Xuejie

2015-01-01

7

Inorganic rechargeable non-aqueous cell  

DOEpatents

A totally inorganic non-aqueous rechargeable cell having an alkali or alkaline earth metal anode such as of lithium, a sulfur dioxide containing electrolyte and a discharging metal halide cathode, such as of CuCl.sub.2, CuBr.sub.2 and the like with said metal halide being substantially totally insoluble in SO.sub.2 and admixed with a conductive carbon material.

Bowden, William L. (Nashua, NH); Dey, Arabinda N. (Needham, MA)

1985-05-07

8

Interconnected network of MnO2 nanowires with a "cocoonlike" morphology: redox couple-mediated performance enhancement in symmetric aqueous supercapacitor.  

PubMed

Low electronic conductivity and slow faradic processes limit the performance of MnO2 as an electrochemical pseudocapacitor with respect to cycling and power density. Herein, we report preparation of single-phase ?-MnO2, composed of an interconnected nanowire network with "cocoonlike" morphology, and its application as electrode in a symmetric aqueous supercapacitor. Increased "effective" surface area, coexistence of micropores and mesopores, and enhanced electron transport in these nanowire networks result in a specific pseudocapacitance (CS) of 775 F·g(-1) in 3 M KOH, derived from cyclic voltammetry in the potential window of -1 to +1 V at a scan rate of 2 mV·s(-1), the highest reported for two-electrode symmetric configuration. Furthermore, introduction of K4Fe(CN)6 as a redox-active additive to KOH results in ?7 times increase in energy density at a power density of ?6000 W·kg(-1). The presence of the Fe(CN)6(4-)/Fe(CN)6(3-) redox couple provides an electron buffer source compensating for the slow faradic reactions. The results demonstrate that this simple approach might be an effective way to enhance the redox kinetics and reversibility of transition metal oxide-based pseudocapacitors. PMID:24930698

Maiti, Sandipan; Pramanik, Atin; Mahanty, Sourindra

2014-07-01

9

Silicon anode for rechargeable aqueous lithium-air batteries  

NASA Astrophysics Data System (ADS)

A novel aqueous lithium-air rechargeable cell with the configuration of Si/1 M LiClO4 in ethylene carbonate-diethylene carbonate/Li1+x+yAlx(Ti,Ge)2-xP3-ySiyO12/5 M LiCl-1 M LiOH aqueous solution/carbon black, air is proposed. A silicon anode composed of mechanically milled silicon power with an average particle size of ca. 0.5 ?m, vapor grown carbon fiber and a polyimide binder was examined. The open-circuit voltage at the charged state was 2.9 V at 25 °C. The discharge capacity of 700 mAh g-silicon-1 was retained for 40 cycles at 0.3 mA cm-2 with cut-off voltages of 3.5 and 1.5 V. Significant capacity fade was observed at deep charge and discharge cycling at 2000 mAh g-silicon-1.

Teranishi, R.; Si, Q.; Mizukoshi, F.; Kawakubo, M.; Matsui, M.; Takeda, Y.; Yamamoto, O.; Imanishi, N.

2015-01-01

10

Capacitance behavior of nanostructured ?-MnO2/C composite electrode using different carbons matrix  

NASA Astrophysics Data System (ADS)

In this work nanostructured ?-MnO2/C composite electrode was synthesized via the reduction reaction of potassium permanganate. A wide range of carbons such as mesoporous carbon (MC), graphite (GC), super P carbon (super P) and Vulcan carbon (VC) were used in order to enhance the interfacial electrical conductivity and the electrochemical capacitance of the composite electrodes. Physical properties, structure and specific surface area of electrode materials were investigated by scanning electron microscopy (SEM), x-ray diffraction and nitrogen adsorption measurements. The capacitance behavior of MnO2/C materials was studied in aqueous and non-aqueous solution using cyclic voltammetry, galvanostatic charge/discharge and impedance spectroscopy measurements. The composite electrode exhibits the highest capacitance at 30 wt% activated carbon. Among different carbons used, the maximum capacitance of MnO2/super P electrode is as high as 205 F g?1 at 50 mV s?1 and retains 98% after 300 cycles.

Tran, Van Man; Ha, An The; Loan Phung Le, My

2014-06-01

11

Synthesis and characterization of different MnO2 morphologies for lithium-air batteries  

NASA Astrophysics Data System (ADS)

Manganese dioxide (MnO2) was synthesized in the forms of nanorods, nanoparticles, and mesoporous structures and the characteristics of these materials were investigated. Crystallinities were studied by x-ray diffraction and morphologies by scanning and transmission electron microscopy. Average pore sizes and specific surface areas were analyzed using the Barret-Joyner-Halenda and Brunauer-Emmett-Teller methods, respectively. Samples were also studied by cyclic voltammetry using 1M aqueous KOH solution saturated with either O2 or N2 as electrolytes to investigate their ORR (oxygen reduction reaction) and OER (oxygen evolution reaction) activities. Of the samples produced, mesoporous MnO2 exhibited the highest ORR and OER catalytic activities. Mesoporous MnO2 supported on a gas diffusion layer was also used as a catalyst on the air electrode (cathode) of a lithium-air battery in organic electrolyte. The charge-discharge behavior of mesoporous MnO2 was investigated at a current density 0.2 mAcm-2 in a pure oxygen environment. Mesoporous MnO2 electrodes showed stable cycleability up to 65 cycles at a cell capacity of 700 mAhg-1.

Choi, Hyun-A.; Jang, Hyuk; Hwang, Hyein; Choi, Mincheol; Lim, Dongwook; Shim, Sang Eun; Baeck, Sung-Hyeon

2014-09-01

12

An aqueous rechargeable formate-based hydrogen battery driven by heterogeneous Pd catalysis.  

PubMed

The formate-based rechargeable hydrogen battery (RHB) promises high reversible capacity to meet the need for safe, reliable, and sustainable H2 storage used in fuel cell applications. Described herein is an additive-free RHB which is based on repetitive cycles operated between aqueous formate dehydrogenation (discharging) and bicarbonate hydrogenation (charging). Key to this truly efficient and durable H2 handling system is the use of highly strained Pd nanoparticles anchored on graphite oxide nanosheets as a robust and efficient solid catalyst, which can facilitate both the discharging and charging processes in a reversible and highly facile manner. Up to six repeated discharging/charging cycles can be performed without noticeable degradation in the storage capacity. PMID:25382034

Bi, Qing-Yuan; Lin, Jian-Dong; Liu, Yong-Mei; Du, Xian-Long; Wang, Jian-Qiang; He, He-Yong; Cao, Yong

2014-12-01

13

An aqueous rechargeable lithium battery using coated Li metal as anode.  

PubMed

New energy industry including electric vehicles and large-scale energy storage in smart grids requires energy storage systems of good safety, high reliability, high energy density and low cost. Here a coated Li metal is used as anode for an aqueous rechargeable lithium battery (ARLB) combining LiMn2O4 as cathode and 0.5?mol l(-1) Li2SO4 aqueous solution as electrolyte. Due to the "cross-over" effect of Li(+) ions in the coating, this ARLB delivers an output voltage of about 4.0?V, a big breakthrough of the theoretic stable window of water, 1.229?V. Its cycling is very excellent with Coulomb efficiency of 100% except in the first cycle. Its energy density can be 446?Wh kg(-1), about 80% higher than that for traditional lithium ion battery. Its power efficiency can be above 95%. Furthermore, its cost is low and safety is much reliable. It provides another chemistry for post lithium ion batteries. PMID:23466633

Wang, Xujiong; Hou, Yuyang; Zhu, Yusong; Wu, Yuping; Holze, Rudolf

2013-01-01

14

An Aqueous Rechargeable Lithium Battery Using Coated Li Metal as Anode  

PubMed Central

New energy industry including electric vehicles and large-scale energy storage in smart grids requires energy storage systems of good safety, high reliability, high energy density and low cost. Here a coated Li metal is used as anode for an aqueous rechargeable lithium battery (ARLB) combining LiMn2O4 as cathode and 0.5?mol l?1 Li2SO4 aqueous solution as electrolyte. Due to the “cross-over” effect of Li+ ions in the coating, this ARLB delivers an output voltage of about 4.0?V, a big breakthrough of the theoretic stable window of water, 1.229?V. Its cycling is very excellent with Coulomb efficiency of 100% except in the first cycle. Its energy density can be 446?Wh kg?1, about 80% higher than that for traditional lithium ion battery. Its power efficiency can be above 95%. Furthermore, its cost is low and safety is much reliable. It provides another chemistry for post lithium ion batteries. PMID:23466633

Wang, Xujiong; Hou, Yuyang; Zhu, Yusong; Wu, Yuping; Holze, Rudolf

2013-01-01

15

Impact of environmental conditions on the sorption behavior of radionuclide 63 Ni(II) onto hierarchically structured ?-MnO 2  

Microsoft Academic Search

A novel hierarchically structured ?-MnO2 has been synthesized using a simple chemical reaction between MnSO4 and KMnO4 in aqueous solution without using any templates, surfactants, catalysts, calcination and hydrothermal processes. As an example\\u000a of potential applications, hierarchically structured ?-MnO2 was used as adsorbent in radionuclide 63Ni(II) treatment, and showed an excellent ability. The effects of pH, ionic strength, temperature, humic

Juan Mou; Guoju Wang; Wenxian Shi; Shouwei Zhang

16

Growth of One-Dimensional MnO2 Nanostructure  

NASA Astrophysics Data System (ADS)

Large scale MnO2 nanorods were controllably synthesized from the inexpensive precursors (e.g., manganese acetate, ammonium persulfate) via a facile one-step low temperature hydrothermal strategy. The crystal phase and microscopic morphology of the as-prepared MnO2 nanorods were characterized by X-ray powder diffraction (XRD) and scanning electron microscope (SEM). Through investigating the morphology evolution of MnO2 products in the whole synthesis process, a novel growth mechanism of these MnO2 nanorods was proposed, which may be efficiently extended to other material systems as a general approach towards one-dimensional nanostructures. The obtained MnO2 nanorods may have potential applications in Li-ion batteries and supercapacitors.

Lu, Pai; Xue, Dongfeng

17

High-performance rechargeable lithium-iodine batteries using triiodide/iodide redox couples in an aqueous cathode.  

PubMed

Development of promising battery systems is being intensified to fulfil the needs of long-driving-ranged electric vehicles. The successful candidates for new generation batteries should have higher energy densities than those of currently used batteries and reasonable rechargeability. Here we report that aqueous lithium-iodine batteries based on the triiodide/iodide redox reaction show a high battery performance. By using iodine transformed to triiodide in an aqueous iodide, an aqueous cathode involving the triiodide/iodide redox reaction in a stable potential window avoiding water electrolysis is demonstrated for lithium-iodine batteries. The high solubility of triiodide/iodide redox couples results in an energy density of ~ 0.33?kWh?kg(-1), approximately twice that of lithium-ion batteries. The reversible redox reaction without the formation of resistive solid products promotes rechargeability, demonstrating 100 cycles with negligible capacity fading. A low cost, non-flammable and heavy-metal-free aqueous cathode can contribute to the feasibility of scale-up of lithium-iodine batteries for practical energy storage. PMID:23695690

Zhao, Yu; Wang, Lina; Byon, Hye Ryung

2013-01-01

18

High-voltage and high-rate symmetric supercapacitor based on MnO2-polypyrrole hybrid nanofilm  

NASA Astrophysics Data System (ADS)

A manganese oxide (MnO2) nanosheet film, hybridized with a conducting polymer polypyrrole (PPy), was prepared through the direct reaction of a carbon cloth with potassium permanganate (KMnO4) and through the subsequent chemical polymerization; this type of prepared nanosheet has been used as an electrode for symmetric supercapacitors. The influence of the reaction time in the KMnO4 solution on the capacitive property of the MnO2 film was systematically investigated. Further experimentation revealed that the PPy with the high electrical conductivity had promoted the charge transfer in the MnO2 nanofilm and had played an important role in enhancing the electrode performance (˜45.6 mF cm-2). An areal capacitance of 25.9 mF cm-2 and an excellent rate performance (˜50.08% of the initial capacitance when the scan rate increases 100 times from 2.5 to 250 mV s-1) can be achieved for an aqueous symmetric supercapacitor that is assembled from the MnO2-PPy nanofilm. In particular, an operating voltage of 1.2 V can be delivered by choosing an appropriate electrolyte; this voltage level is much larger than that of traditional aqueous symmetric supercapacitors (?1.0 V) and contributes to a high energy density (˜3.5 ?Wh cm-2). Under such a high output voltage, the device can still maintain ˜86.21% of the initial capacitance, even after 2000 cycles.

Wang, Chong; Zhan, Yang; Wu, Lingxia; Li, Yuanyuan; Liu, Jinping

2014-08-01

19

LiMn2O4 nanotube as cathode material of second-level charge capability for aqueous rechargeable batteries.  

PubMed

LiMn2O4 nanotube with a preferred orientation of (400) planes is prepared by using multiwall carbon nanotubes as a sacrificial template. Because of the nanostructure and preferred orientation, it shows a superfast second-level charge capability as a cathode for aqueous rechargeable lithium battery. At the charging rate of 600C (6 s), 53.9% capacity could be obtained. Its reversible capacity can be 110 mAh/g, and it also presents excellent cycling behavior due to the porous tube structure to buffer the strain and stress from Jahn-Teller effects. PMID:23537381

Tang, Wei; Hou, Yuyang; Wang, Faxing; Liu, Lili; Wu, Yuping; Zhu, Kai

2013-05-01

20

High-energy MnO2 nanowire/graphene and graphene asymmetric electrochemical capacitors.  

PubMed

In order to achieve high energy and power densities, we developed a high-voltage asymmetric electrochemical capacitor (EC) based on graphene as negative electrode and a MnO(2) nanowire/graphene composite (MGC) as positive electrode in a neutral aqueous Na(2)SO(4) solution as electrolyte. MGC was prepared by solution-phase assembly of graphene sheets and ?-MnO(2) nanowires. Such aqueous electrolyte-based asymmetric ECs can be cycled reversibly in the high-voltage region of 0-2.0 V and exhibit a superior energy density of 30.4 Wh kg(-1), which is much higher than those of symmetric ECs based on graphene//graphene (2.8 Wh kg(-1)) and MGC//MGC (5.2 Wh kg(-1)). Moreover, they present a high power density (5000 W kg(-1) at 7.0 Wh kg(-1)) and acceptable cycling performance of ?79% retention after 1000 cycles. These findings open up the possibility of graphene-based composites for applications in safe aqueous electrolyte-based high-voltage asymmetric ECs with high energy and power densities. PMID:20857919

Wu, Zhong-Shuai; Ren, Wencai; Wang, Da-Wei; Li, Feng; Liu, Bilu; Cheng, Hui-Ming

2010-10-26

21

DNA-encapsulated chain and wire-like ?-MnO2 organosol for oxidative polymerization of pyrrole to polypyrrole.  

PubMed

A DNA-encapsulated chain and wire-like ?-MnO2 organosols have been synthesized utilizing a two-phase water-toluene extraction procedure at room temperature (RT). The ?-MnO2 organosol was prepared by transferring KMnO4 and DNA from aqueous solution separately to an organic solvent (toluene) using a phase transfer catalyst, mixing both organic solutions together, and subsequent reduction with NaBH4. The eventual diameters of the MnO2 particles in chain-like and wire-like morphologies were ?1-2 nm and ?1.8 ± 0.2 nm, respectively, whereas the nominal length of the DNA-MnO2 chains was ?2-3 ?m. Different morphologies of the MnO2 organosol were synthesized by simply tuning the DNA to KMnO4 molar ratio. The synthesized particles were successfully re-dispersed in different organic solvents for application in various organic reactions. The potential of the DNA-MnO2 organosol as a catalyst has been tested in the organic catalytic reaction for the oxidative polymerization of pyrrole to polypyrrole, using the DNA-MnO2 organosol as a potential catalyst. The synthesis process was simple, reproducible and robust. In future, the present process might be utilized for the formation of other nanomaterials in organic solvents, with specific morphologies and uses in a variety of catalytic reactions and energy storage applications. PMID:25619572

Ede, Sivasankara Rao; Anantharaj, S; Nithiyanantham, U; Kundu, Subrata

2015-02-01

22

Design and synthesis of hierarchically porous MnO2/carbon hybrids for high performance electrochemical capacitors.  

PubMed

In this study, various morphologies of manganese dioxide (MnO2), including solid spheres, yolk-shell structures, and hollow spheres, are synthesized through an ambient reaction between KMnO4 and carbon sphere. The diversity in crystal structure and morphology of these forms of MnO2 are investigated using detailed X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) observations, and a possible formation mechanism called "inward-outward growth" is proposed. Based on our experimental results, we believe that the final products form through a synergetic effect of outward diffusing carbonaceous fragments and inward diffusing aqueous KMnO4 solution. The rate of inward KMnO4 diffusion relative to the rate of outward carbon diffusion determines the morphology of the MnO2 product. Furthermore, a coated core structure consisting of an internal graphitized carbon sphere and an external MnO2 layer is successfully synthesized, which not only possesses high surface area and hierarchical porosity, but also has improved electrical conductivity. Such structural characteristics enable the obtained composite to show a specific capacitance of 583 F g(-1) at a current density of 1 A g(-1) in 0.1 M Na2SO4 electrolyte. PMID:25454426

Li, Sa; Wang, Chang-An

2015-01-15

23

Periodic current oscillation catalyzed by ?-MnO2 nanosheets.  

PubMed

The oxygen evolution reaction (OER) is of wide interest for both fuel and hydrometallurgy applications. Different types of nanoscale MnO2 , varying from nanosheets to nanoneedles, are synthesized and assembled on the anode to investigate their catalytic effect on the nonlinear kinetics of the MnO2 -catalyzed OER at high current. For ?-MnO2 nanosheets, periodic current oscillations (PCO) occurr and occupy up to 40?% of the total energy consumption. The PCO can help to reduce the energy consumption under constant current conditions. Its amplitude could be twice of that for the previously reported MnO2 grown by an in situ electrochemical method. If the amount of ?-MnO2 nanoneedles increases, the oscillation disappears. For different Mn oxides, the rate constants of H2 O2 decomposition differ, resulting in changes in oscillation features. The results of this study may enable new ideas to improve the efficiency of industrial electrolysis and charging-discharging of supercapacitors. PMID:25382485

Fan, Xing; Yang, Dianpeng; Ding, Lifeng; Du, Jun; Tao, Changyuan

2015-01-12

24

High-capacity nanostructured manganese dioxide cathode for rechargeable magnesium ion batteries  

NASA Astrophysics Data System (ADS)

Nanostructured ?-MnO2 and ?-MnO2 are investigated for use in rechargeable Mg ion battery (MIB) cathodes. In order to prepare nanosized particles, the manganese dioxides are prepared by the acid treatment of spinel MgMn2O4 synthesized using the Pechini method. X-ray diffraction analysis indicates that the resulting MnO2 consists of multiple phases, ?-MnO2, ?-MnO2, and ?-MnO2, depending on the leaching time in acid solution. Upon the first charge-discharge cycle in acetonitrile electrolyte, the ?-MnO2 based electrode shows larger reversible capacity of ?330 mAh g-1 compared to an electrode containing a large amount of ?-MnO2. This enhanced capacity is associated with the facile charge-transfer reaction of Mg ions at the MnO2/electrolyte interfaces. The capacity fading of MnO2 in different electrolytes is also discussed in terms of the formation of a surface layer at the electrode/electrolyte interface during the charging process.

Kim, Ju-Sik; Chang, Won-Seok; Kim, Ryoung-Hee; Kim, Dong-Young; Han, Dong-Wook; Lee, Kyu-Hyoung; Lee, Seok-Soo; Doo, Seok-Gwang

2015-01-01

25

Hydrothermal synthesis of MnO2/CNT nanocomposite with a CNT core/porous MnO2 sheath hierarchy architecture for supercapacitors  

PubMed Central

MnO2/carbon nanotube [CNT] nanocomposites with a CNT core/porous MnO2 sheath hierarchy architecture are synthesized by a simple hydrothermal treatment. X-ray diffraction and Raman spectroscopy analyses reveal that birnessite-type MnO2 is produced through the hydrothermal synthesis. Morphological characterization reveals that three-dimensional hierarchy architecture is built with a highly porous layer consisting of interconnected MnO2 nanoflakes uniformly coated on the CNT surface. The nanocomposite with a composition of 72 wt.% (K0.2MnO2·0.33 H2O)/28 wt.% CNT has a large specific surface area of 237.8 m2/g. Electrochemical properties of the CNT, the pure MnO2, and the MnO2/CNT nanocomposite electrodes are investigated by cyclic voltammetry and electrochemical impedance spectroscopy measurements. The MnO2/CNT nanocomposite electrode exhibits much larger specific capacitance compared with both the CNT electrode and the pure MnO2 electrode and significantly improves rate capability compared to the pure MnO2 electrode. The superior supercapacitive performance of the MnO2/CNT nancomposite electrode is due to its high specific surface area and unique hierarchy architecture which facilitate fast electron and ion transport. PMID:24576342

2012-01-01

26

New-concept Batteries Based on Aqueous Li+/Na+ Mixed-ion Electrolytes  

PubMed Central

Rechargeable batteries made from low-cost and abundant materials operating in safe aqueous electrolytes are attractive for large-scale energy storage. Sodium-ion battery is considered as a potential alternative of current lithium-ion battery. As sodium-intercalation compounds suitable for aqueous batteries are limited, we adopt a novel concept of Li+/Na+ mixed-ion electrolytes to create two batteries (LiMn2O4/Na0.22MnO2 and Na0.44MnO2/TiP2O7), which relies on two electrochemical processes. One involves Li+ insertion/extraction reaction, and the other mainly relates to Na+ extraction/insertion reaction. Two batteries exhibit specific energy of 17?Wh kg?1 and 25?Wh kg?1 based on the total weight of active electrode materials, respectively. As well, aqueous LiMn2O4/Na0.22MnO2 battery is capable of separating Li+ and Na+ due to its specific mechanism unlike the traditional “rocking-chair” lithium-ion batteries. Hence, the Li+/Na+ mixed-ion batteries offer promising applications in energy storage and Li+/Na+ separation. PMID:23736113

Chen, Liang; Gu, Qingwen; Zhou, Xufeng; Lee, Saixi; Xia, Yonggao; Liu, Zhaoping

2013-01-01

27

New-concept batteries based on aqueous Li+/Na+ mixed-ion electrolytes.  

PubMed

Rechargeable batteries made from low-cost and abundant materials operating in safe aqueous electrolytes are attractive for large-scale energy storage. Sodium-ion battery is considered as a potential alternative of current lithium-ion battery. As sodium-intercalation compounds suitable for aqueous batteries are limited, we adopt a novel concept of Li(+)/Na(+) mixed-ion electrolytes to create two batteries (LiMn2O4/Na0.22MnO2 and Na0.44MnO2/TiP2O7), which relies on two electrochemical processes. One involves Li(+) insertion/extraction reaction, and the other mainly relates to Na(+) extraction/insertion reaction. Two batteries exhibit specific energy of 17 Wh kg(-1) and 25 Wh kg(-1) based on the total weight of active electrode materials, respectively. As well, aqueous LiMn2O4/Na0.22MnO2 battery is capable of separating Li(+) and Na(+) due to its specific mechanism unlike the traditional "rocking-chair" lithium-ion batteries. Hence, the Li(+)/Na(+) mixed-ion batteries offer promising applications in energy storage and Li(+)/Na(+) separation. PMID:23736113

Chen, Liang; Gu, Qingwen; Zhou, Xufeng; Lee, Saixi; Xia, Yonggao; Liu, Zhaoping

2013-01-01

28

New-concept Batteries Based on Aqueous Li+/Na+ Mixed-ion Electrolytes  

NASA Astrophysics Data System (ADS)

Rechargeable batteries made from low-cost and abundant materials operating in safe aqueous electrolytes are attractive for large-scale energy storage. Sodium-ion battery is considered as a potential alternative of current lithium-ion battery. As sodium-intercalation compounds suitable for aqueous batteries are limited, we adopt a novel concept of Li+/Na+ mixed-ion electrolytes to create two batteries (LiMn2O4/Na0.22MnO2 and Na0.44MnO2/TiP2O7), which relies on two electrochemical processes. One involves Li+ insertion/extraction reaction, and the other mainly relates to Na+ extraction/insertion reaction. Two batteries exhibit specific energy of 17 Wh kg-1 and 25 Wh kg-1 based on the total weight of active electrode materials, respectively. As well, aqueous LiMn2O4/Na0.22MnO2 battery is capable of separating Li+ and Na+ due to its specific mechanism unlike the traditional ``rocking-chair'' lithium-ion batteries. Hence, the Li+/Na+ mixed-ion batteries offer promising applications in energy storage and Li+/Na+ separation.

Chen, Liang; Gu, Qingwen; Zhou, Xufeng; Lee, Saixi; Xia, Yonggao; Liu, Zhaoping

2013-06-01

29

Li Intercalation into a ?-MnO2 Grain Boundary.  

PubMed

MnO2 is well-known for its technological applications including Li ion, Li-air batteries, and electrochemical capacitors. Compared to the bulk material, nanostructuring of rutile (?-)MnO2 has been shown to vastly improve its electrochemical properties and performance. While the bulk material cannot readily intercalate Li, nanostructured mesoporous samples exhibit good Li intercalation. This observation is not yet fully understood. In this work, we use state-of-the-art theoretical techniques to investigate Li intercalation and migration at the ?-MnO2 ? 5(210)/[001] grain boundary (GB). We show how large tunnel structures in the GB can promote Li intercalation with voltages of up to 3.83 eV compared to the experimental value of 3.00 eV. Conversely, small tunnel structures resulting from overcoordination of ions at the GB can hinder Li intercalation with significantly reduced voltages. The size and shape of these tunnels also strongly influence the energetics of Li migration with energy barriers ranging from 0.15 to 0.89 eV, compared to a value for the bulk of 0.17 eV. Our results illustrate how GBs with large, open tunnel structures may promote electrochemical performance and could be a contributing factor to the excellent performance of nanostructured ?-MnO2. PMID:25808228

Dawson, James A; Tanaka, Isao

2015-04-22

30

Two-Dimensional ?-MnO2 Nanowire Network with Enhanced Electrochemical Capacitance  

PubMed Central

Conventional crystalline ?-MnO2 usually exhibits poor electrochemical activities due to the narrow tunnels in its rutile-type structure. In this study, we synthesized a novel 2D ?-MnO2 network with long-range order assembled by ?-MnO2 nanowires and demonstrated that the novel 2D ?-MnO2 network exhibits enhanced electrochemical performances. The 2D network is interwoven by crossed uniform ?-MnO2 nanowires and the angle between the adjacent nanowires is about 60°. Such a novel structure makes efficient contact of ?-MnO2 with electrolyte during the electrochemical process, decreases the polarization of the electrode and thus increases the discharge capacity and high-rate capability. The specific capacitance of the obtained 2D ?-MnO2 network is 453.0 F/g at a current density of 0.5?A/g. PMID:23846740

Wei, Chengzhen; Pang, Huan; Zhang, Bo; Lu, Qingyi; Liang, Shuang; Gao, Feng

2013-01-01

31

Polypyrrole-encapsulated vanadium pentoxide nanowires on a conductive substrate for electrode in aqueous rechargeable lithium battery.  

PubMed

Precursors of ammonium vanadium bronze (NH4V4O10) nanowires assembled on a conductive substrate were prepared by a hydrothermal method. After calcination at 360°C, the NH4V4O10 precursor transformed to vanadium pentoxide (V2O5) nanowires, which presented a high initial capacity of 135.0mA h g(-1) at a current density of 50mA g(-1) in 5M LiNO3 aqueous solution; while the specific capacity faded quickly over 50 cycles. By coating the surface of V2O5 nanowires with water-insoluble polypyrrole (PPy), the formed nanocomposite electrode exhibited a specific discharge capacity of 89.9mA h g(-1) at 50mA g(-1) (after 100 cycles). A V2O5@PPy //LiMn2O4 rechargeable lithium battery exhibited an initial discharge capacity of 95.2mA h g(-1); and after 100 cycles, a specific discharge capacity of 81.5mA h g(-1) could retain at 100mA g(-1). PMID:25463177

Liang, Chaowei; Fang, Dong; Cao, Yunhe; Li, Guangzhong; Luo, Zhiping; Zhou, Qunhua; Xiong, Chuanxi; Xu, Weilin

2015-02-01

32

Preparation of MnO 2 \\/WMNT composite and MnO 2 \\/AB composite by redox deposition method and its comparative study as supercapacitive materials  

Microsoft Academic Search

The manganese oxide\\/multi-walled carbon nanotube (MnO2\\/MWNT) composite and the manganese oxide\\/acetylene black (MnO2\\/AB) composite were prepared by translating potassium permanganate into MnO2 which formed the above composite with residual carbon material using the redox deposition method and carbon as a reducer.\\u000a The products were characterized by X-ray diffraction, Fourier transform infrared, and scanning electron microscope. Electrochemical\\u000a properties of both the

Hong-Yan Chu; Qiong-Yu Lai; Ling Wang; Jian-Fang Lu; Yan Zhao

2010-01-01

33

?-MnO 2 nano-sieve membrane: preparation, characterization and reaction studies  

NASA Astrophysics Data System (ADS)

?-MnO 2 nano-sieve membrane was synthesized using ?-MnO 2 nanometer powders by suspending particles sintering method. The results of BET, AFM, and SEM indicate that ?-MnO 2 nano-sieve membrane with a thickness of about 2 ?m is porous (pore size 4 nm), and has a smooth surface. The results of XRD and TPR exhibit that the phase transformation which can be suppressed at La/Mn = 0.15, and the activity of oxygen center of ?-MnO 2 nano-sieve membrane (La/Mn = 0.15) is slightly lower than that of ?-MnO 2 nanometer powders. ?-MnO 2 nano-sieve membrane shows a higher separation factor of H 2/Ar in the range of 50-300 °C. In addition, the ?-MnO 2 nano-sieve membrane was applied to the membrane reactor for cyclohexane oxidative dehydrogenation, and the effect of temperature on cyclohexane conversion was investigated. The result shows that cyclohexane conversion in the ?-MnO 2 nano-sieve membrane reactor is higher than that in the conventional packed bed reactor.

Zhao, Lili; Wang, Rongshu

2004-09-01

34

Critical evaluation of the colossal Seebeck coefficient of nanostructured rutile MnO2.  

PubMed

We have explored the correlation between the Seebeck coefficient and the electronic structure of nanostructured rutile MnO2 using density functional theory to critically appraise the three orders of magnitude scatter in literature data. Our hypothesis is that the microstructure and morphology on the nanoscale is causing this behaviour, which we have tested by comparing the Seebeck coefficient of bulk MnO2 with two low-energy surfaces: MnO2(1?1?0) and MnO2(0?0?1). From these data, it is evident that variations over two orders of magnitude in the Seebeck coefficient can be attained by affecting domain size and texture on the nanoscale. This may be understood by analysing the electronic structure. Surface hybridized Mn d-O p states fill the band gap of MnO2 and thus substantially alter the transport properties. PMID:25730181

Music, Denis; Schneider, Jochen M

2015-03-25

35

Critical evaluation of the colossal Seebeck coefficient of nanostructured rutile MnO2  

NASA Astrophysics Data System (ADS)

We have explored the correlation between the Seebeck coefficient and the electronic structure of nanostructured rutile MnO2 using density functional theory to critically appraise the three orders of magnitude scatter in literature data. Our hypothesis is that the microstructure and morphology on the nanoscale is causing this behaviour, which we have tested by comparing the Seebeck coefficient of bulk MnO2 with two low-energy surfaces: MnO2(1?1?0) and MnO2(0?0?1). From these data, it is evident that variations over two orders of magnitude in the Seebeck coefficient can be attained by affecting domain size and texture on the nanoscale. This may be understood by analysing the electronic structure. Surface hybridized Mn d–O p states fill the band gap of MnO2 and thus substantially alter the transport properties.

Music, Denis; Schneider, Jochen M.

2015-03-01

36

High dispersion of ?-MnO 2 on well-aligned carbon nanotube arrays and its application in supercapacitors  

Microsoft Academic Search

The well-aligned carbon nanotube arrays (ACNTs) were used as supporting material and the ?-MnO2\\/ACNT electrode with high dispersion of ?-MnO2 has been prepared by electrochemically induced deposition method. The crystal structure and morphology of the ?-MnO2\\/ACNT electrode were investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The capacitive properties of ?-MnO2\\/ACNT electrode were characterized by cyclic voltammetry

Zhen Fan; Jinhua Chen; Bing Zhang; Bo Liu; Xinxian Zhong; Yafei Kuang

2008-01-01

37

Adsorption of REE(III)-humate complexes onto MnO 2: Experimental evidence for cerium anomaly and lanthanide tetrad effect suppression  

NASA Astrophysics Data System (ADS)

Experiments were conducted to evaluate the impact of organic complexation on the development of Ce anomalies and the lanthanide tetrad effect during the adsorption of rare-earth elements (REE) onto MnO 2. Two types of aqueous solutions—NaCl and NaNO 3—were tested at pH 5 and 7.5. Time-series experiments indicate that a steady-state is reached within less than 10 h when REE occur as free inorganic species, whereas steady state is not reached before 10 d when REE occur as REE-humate complexes. The distribution coefficients (K dREE) between suspended MnO 2 and solution show no or only very weak positive Ce anomaly or lanthanide tetrad effect when REE occur as humate complexes, unlike the results obtained in experiments with REE occurring as free inorganic species. Monitoring of dissolved organic carbon (DOC) concentrations show that log K dREE organic/K dDOC ratios are close to 1.0, implying that the REE and humate remain bound to each other upon adsorption. Most likely, the Ce anomaly reduction/suppression in the organic experiments arises from a combination of two processes: (i) inability of MnO 2 to oxidize Ce(III) because of shielding of MnO 2 surfaces by humate molecules and (ii) Ce(IV) cannot be preferentially removed from solution due to quantitative complexation of the REE by organic matter. We suggest that the lack of lanthanide tetrad effect arises because the adsorption of REE-humate complexes onto MnO 2 occurs dominantly via the humate side of the complexes (anionic adsorption), thereby preventing expression of the differences in Racah parameters for 4f electron repulsion between REE and the oxide surface. The results presented here explain why, despite the development of strongly oxidizing conditions and the presence of MnO 2 in the aquifer, no (or insignificant) negative Ce anomalies are observed in organic-rich waters. The present study demonstrates experimentally that the Ce anomaly cannot be used as a reliable proxy of redox conditions in organic-rich waters or in precipitates formed at equilibrium with organic-rich waters.

Davranche, Mélanie; Pourret, Olivier; Gruau, Gérard; Dia, Aline; Le Coz-Bouhnik, Martine

2005-10-01

38

Controllable synthesis of MnO2/polyaniline nanocomposite and its electrochemical capacitive property  

PubMed Central

Polyaniline (PANI) and MnO2/PANI composites are simply fabricated by one-step interfacial polymerization. The morphologies and components of MnO2/PANI composites are modulated by changing the pH of the solution. Formation procedure and capacitive property of the products are investigated by XRD, FTIR, TEM, and electrochemical techniques. We demonstrate that MnO2 as an intermedia material plays a key role in the formation of sample structures. The MnO2/PANI composites exhibit good cycling stability as well as a high capacitance close to 207 F?g?1. Samples fabricated with the facile one-step method are also expected to be adopted in other field such as catalysis, lithium ion battery, and biosensor. PMID:23594724

2013-01-01

39

Binder free synthesis of MnO2 nanoplates/graphene composites with enhanced supercapacitive properties  

NASA Astrophysics Data System (ADS)

MnO2 nanoplates grown on graphene sheets have been directly synthesized during the graphite oxide (GO) reduction. The synthetic method is efficient, green and controllable with GO reduced and MnO2 nanoplates formed in one step. Compared with conventional methods, this method is easier to implement without using binders or any conductive additives. The as-prepared MnO2 nanoplates and graphene composites (GM) electrodes exhibit enhanced electrochemical performances, including ultrahigh specific capacitance (385 F g-1, at current density of 1 A g-1) and excellent cycling stabilities with 1 M Na2SO4 electrolytes. This improvement is due to the tighter contact between graphene sheets and MnO2 nanoplates, and the higher conductive and capacitive characteristics of graphene.

Li, Zijiong; Su, Yuling; Yun, Gaoqian; Shi, Kai; Lv, Xiaowei; Yang, Baocheng

2014-08-01

40

Nanostructured MnO 2\\/exfoliated graphite composite electrode as supercapacitors  

Microsoft Academic Search

Nanostructured manganese oxides\\/exfoliated graphite composite (MnO2\\/EG) were synthesized via a new sol–gel route. Scanning electron microscope (SEM) was employed for surface morphology and X-ray diffraction (XRD) was used for structure characterization. Cyclic voltammetry (CV), galvanostatic charge\\/discharge, and the electrochemical impedance measurements were applied to investigate the electrochemical performance of the MnO2\\/EG composite electrodes. When used for electrodes of supercapacitors, the

Yan-jing Yang; En-Hui Liu; Li-min Li; Zheng-zheng Huang; Hai-jie Shen; Xiao-xia Xiang

2009-01-01

41

MnO2 nanolayers on highly conductive TiO(0.54)N(0.46) nanotubes for supercapacitor electrodes with high power density and cyclic stability.  

PubMed

Pseudo-capacitive MnO2 supercapacitors are attracting intense interest because of the theoretically high specific capacitance (1370 F g(-1)) and low cost of MnO2. For the practical application, the power density and the cyclic stability of MnO2-based supercapacitors are expected to be improved. Increasing the efficiency of the current collection is an effective method to improve the power density for a given supercapacitor. Here, the highly conductive and electrochemically stable material, titanium oxynitride (TiO0.54N0.46), is used as the current collector. Uniform amorphous MnO2 nanolayers were deposited on metal-phase TiO0.54N0.46 nanotube arrays using a modified electrochemical deposition method. The resulting MnO2 supercapacitors exhibited a high power density of 620 kW kg(-1) at an energy density of 9.8 W h kg(-1). This is comparable to high-performance carbon-based electrochemical double layer capacitors in aqueous electrolytes. The high electron transport was enhanced with a highly conductive TiO0.54N0.46 scaffold. Ion transport was promoted in the nanotube structures that had porous walls. In addition, the close interfacial connection between MnO2 and TiO0.54N0.46 contributed to the excellent cyclic stability (ca. 92.0% capacitance retention after 100?000 cycles). These results indicated that the highly conductive and electrochemically stable titanium oxynitride is an excellent candidate for use as an electrode material in high performance supercapacitors. PMID:24668150

Wang, Zhiqiang; Li, Zhaosheng; Feng, Jianyong; Yan, Shicheng; Luo, Wenjun; Liu, Jianguo; Yu, Tao; Zou, Zhigang

2014-05-14

42

Functionalization of biomass carbonaceous aerogels: selective preparation of MnO2@CA composites for supercapacitors.  

PubMed

Functionalized porous carbon materials with hierarchical structure and developed porosity coming from natural and renewable biomass have been attracting tremendous attention recently. In this work, we present a facile and scalable method to synthesize MnO2 loaded carbonaceous aerogel (MnO2@CA) composites via the hydrothermal carbonaceous (HTC) process. We employ two reaction systems of the mixed metal ion precursors to study the optimal selective adsorption and further reaction of MnO2 precursor on CA. Our experimental results show that the system containing KMnO4 and Na2S2O3·5H2O exhibits better electrochemical properties compared with the reaction system of MnSO4·H2O and (NH4)2S2O8. For the former, the obtained MnO2@CA displays the specific capacitance of 123.5 F·g(-1). The enhanced supercapacitance of MnO2@CA nanocomposites could be ascribed to both electrochemical contributions of the loaded MnO2 nanoparticles and the porous structure of three-dimensional carbonaceous aerogels. This study not only indicates that it is vital for the reaction systems to match with porous carbonaceous materials, but also offers a new fabrication strategy to prepare lightweight and high-performance materials that can be used in energy storage devices. PMID:24882146

Ren, Yumei; Xu, Qun; Zhang, Jianmin; Yang, Hongxia; Wang, Bo; Yang, Daoyuan; Hu, Junhua; Liu, Zhimin

2014-06-25

43

Effect of MnO2 Addition on the Electrical Properties of PNZST Ceramics  

NASA Astrophysics Data System (ADS)

(Pb0.99Nb0.02)[(Zr0.70Sn0.30) x Ti1- x ]0.98O3 (PNZST) piezoelectric ceramics of pure perovskite structure were prepared by a conventional ceramic fabrication method, where x = 0.48-0.56. When x = 0.52, the ceramics exhibit a high piezoelectric coefficient ( d 33 ˜ 490), but the mechanical quality factor ( Q m) is only 72. To increase the Q m and not dramatically lower the d 33, MnO2 was chosen as the additive. The effects of adding MnO2 on the sinterability, structure, and electrical properties of PNZST ceramics were investigated in detail. With a small addition of MnO2 (?0.6 wt.%), the Mn ions are homogeneously dissolved in the PNZST ceramic, leading to full densification when sintered at 1,300 °C. However, further addition of MnO2 prevents densification, causing a high porosity and small grain size. The doping of MnO2 transforms the phase structure from tetragonal to rhombohedral. The addition of MnO2 up to a maximum of 0.6 wt.% remarkably improves the mechanical quality factor ( Q m) of PNZST ceramics, simultaneously as well as maintaining a high d 33 and k p. PNZST with 0.6 wt.% MnO2 exhibits excellent electrical properties with piezoelectric coefficient d 33 = 392 pC/N, electromechanical coupling factor k p = 0.60, mechanical quality factor Q m = 1,050, dielectric constant ? r = 1,232, dielectric dissipation tan ? = 0.0058, and Curie temperature T C = 300 °C.

Yan, Yangxi; He, Hongliang; Feng, Yujun

2014-05-01

44

Birnessite (?-MnO2) Mediated Degradation of Organoarsenic Feed Additive p-Arsanilic Acid.  

PubMed

p-Arsanilic acid (p-ASA), is a widely used animal feed additive in many developing countries, and is often introduced to agricultural soils with animal wastes. A common soil metal oxide, birnessite (?-MnO2), was found to mediate its degradation with fast rates under acidic conditions. Experimental results indicate that adsorption and degradation of p-ASA on the surface of ?-MnO2 were highly pH dependent, and the overall kinetics for p-ASA degradation and formation of precursor complex could be described by a retarded first-order rate model. For the reaction occurring between pH 4.0 and 6.2, the initial rate equation was determined to be rinit = 2.36 × 10(-5)[ASA](0.8)[MnO2](0.9)[H(+)](0.7). p-ASA first forms a surface precursor complex on ?-MnO2 during degradation, followed by formation of p-ASA radicals through single-electron transfer to ?-MnO2. The p-ASA radicals subsequently undergo cleavage of arsenite group (which is further oxidized to arsenate) or radical-radical self-coupling. Instead of full mineralization (with respect to arsenic only), about one-fifth of the p-ASA "couples" to form an arsenic-bearing azo compound that binds strongly on ?-MnO2. The fast transformation of p-ASA to arsenite and arsenate mediated by ?-MnO2 significantly increases the risk of soil arsenic pollution and deserves significant attention in the animal farming zones still using this feed additive. PMID:25679412

Wang, Lingling; Cheng, Hefa

2015-03-17

45

Galvanostatically deposited Fe: MnO2 electrodes for supercapacitor application  

NASA Astrophysics Data System (ADS)

The present investigation describes the addition of iron (Fe) in order to improve the supercapacitive properties of MnO2 electrodes using galvanostatic mode. These amorphous worm like Fe: MnO2 electrodes are characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDAX), Fourier transform infrared spectroscopy (FTIR) and wettability test. The supercapacitive properties of MnO2 and Fe: MnO2 electrodes are investigated using cyclic voltammetry, chronopotentiometry and impedance techniques. It is seen that the supercapacitance increases with increase in Fe doping concentration and achieved a maximum of 173 F g-1 at 2 at% Fe doping. The maximum supercapacitance obtained is 218 F g-1 for 2 at% Fe: MnO2 electrode. This hydrous binary oxide exhibited ideal capacitive behavior with high reversibility and high pulse charge-discharge property between -0.1 and +0.9 V/SCE in 1 M Na2SO4 electrolyte indicating a promising electrode material for electrochemical supercapacitors.

Dubal, D. P.; Kim, W. B.; Lokhande, C. D.

2012-01-01

46

Uncoupled surface spin induced exchange bias in ?-MnO2 nanowires.  

PubMed

We have studied the microstructure, surface states, valence fluctuations, magnetic properties, and exchange bias effect in MnO2 nanowires. High purity ?-MnO2 rectangular nanowires were synthesized by a facile hydrothermal method with microwave-assisted procedures. The microstructure analysis indicates that the nanowires grow in the [0 0 1] direction with the (2 1 0) plane as the surface. Mn(3+) and Mn(2+) ions are not found in the system by X-ray photoelectron spectroscopy. The effective magnetic moment of the manganese ions fits in with the theoretical and experimental values of Mn(4+) very well. The uncoupled spins in 3d(3) orbitals of the Mn(4+) ions in MnO6 octahedra on the rough surface are responsible for the net magnetic moment. Spin glass behavior is observed through magnetic measurements. Furthermore, the exchange bias effect is observed for the first time in pure ?-MnO2 phase due to the coupling of the surface spin glass with the antiferromagnetic ?-MnO2 matrix. These ?-MnO2 nanowires, with a spin-glass-like behavior and with an exchange bias effect excited by the uncoupled surface spins, should therefore inspire further study concerning the origin, theory, and applicability of surface structure induced magnetism in nanostructures. PMID:25319531

Li, Wenxian; Zeng, Rong; Sun, Ziqi; Tian, Dongliang; Dou, Shixue

2014-01-01

47

Uncoupled surface spin induced exchange bias in ?-MnO2 nanowires  

NASA Astrophysics Data System (ADS)

We have studied the microstructure, surface states, valence fluctuations, magnetic properties, and exchange bias effect in MnO2 nanowires. High purity ?-MnO2 rectangular nanowires were synthesized by a facile hydrothermal method with microwave-assisted procedures. The microstructure analysis indicates that the nanowires grow in the [0 0 1] direction with the (2 1 0) plane as the surface. Mn3+ and Mn2+ ions are not found in the system by X-ray photoelectron spectroscopy. The effective magnetic moment of the manganese ions fits in with the theoretical and experimental values of Mn4+ very well. The uncoupled spins in 3d3 orbitals of the Mn4+ ions in MnO6 octahedra on the rough surface are responsible for the net magnetic moment. Spin glass behavior is observed through magnetic measurements. Furthermore, the exchange bias effect is observed for the first time in pure ?-MnO2 phase due to the coupling of the surface spin glass with the antiferromagnetic ?-MnO2 matrix. These ?-MnO2 nanowires, with a spin-glass-like behavior and with an exchange bias effect excited by the uncoupled surface spins, should therefore inspire further study concerning the origin, theory, and applicability of surface structure induced magnetism in nanostructures.

Li, Wenxian; Zeng, Rong; Sun, Ziqi; Tian, Dongliang; Dou, Shixue

2014-10-01

48

Uncoupled surface spin induced exchange bias in ?-MnO2 nanowires  

PubMed Central

We have studied the microstructure, surface states, valence fluctuations, magnetic properties, and exchange bias effect in MnO2 nanowires. High purity ?-MnO2 rectangular nanowires were synthesized by a facile hydrothermal method with microwave-assisted procedures. The microstructure analysis indicates that the nanowires grow in the [0 0 1] direction with the (2 1 0) plane as the surface. Mn3+ and Mn2+ ions are not found in the system by X-ray photoelectron spectroscopy. The effective magnetic moment of the manganese ions fits in with the theoretical and experimental values of Mn4+ very well. The uncoupled spins in 3d3 orbitals of the Mn4+ ions in MnO6 octahedra on the rough surface are responsible for the net magnetic moment. Spin glass behavior is observed through magnetic measurements. Furthermore, the exchange bias effect is observed for the first time in pure ?-MnO2 phase due to the coupling of the surface spin glass with the antiferromagnetic ?-MnO2 matrix. These ?-MnO2 nanowires, with a spin-glass-like behavior and with an exchange bias effect excited by the uncoupled surface spins, should therefore inspire further study concerning the origin, theory, and applicability of surface structure induced magnetism in nanostructures. PMID:25319531

Li, Wenxian; Zeng, Rong; Sun, Ziqi; Tian, Dongliang; Dou, Shixue

2014-01-01

49

Facile synthesis of hierarchical hollow ?-MnO2 spheres and their application in supercapacitor electrodes  

NASA Astrophysics Data System (ADS)

The hierarchical hollow microspheres of ?-MnO2 have been synthesized through a facile chemical method at room temperature followed by selective removal of manganese carbonate structures with HCl. The microstructure and morphologies of the resulting materials are investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results indicate that the product obtained by simple reaction for 3 min has a porous shell with excellent permeability and uniform pore-size distribution. Electrochemical properties were characterized by cyclic voltammetry, galvanostatic charge/discharge and impedance spectra. As a result, the hierarchical hollow ?-MnO2 showed the specific capacitance of 115 F g-1 at 0.5 A g-1. These results demonstrate that the ?-MnO2 as electrode materials have potential application for high-performance supercapacitors.

Han, Dandan; Jing, Xiaoyan; Xu, Pengcheng; Ding, Yuansheng; Liu, Jingyuan

2014-10-01

50

Magnetic properties in ?-MnO2 doped with alkaline elements  

PubMed Central

?-MnO2 nanotubes were fabricated using a hydrothermal technique. Li, Na and K ions were introduced into MnO2 nanotubes to tailor their magnetic properties. It was found that with a doping concentration lower than 12 at%, the nanotubes showed ferromagnetic-like ordering at low temperature (<50?K), while antiferromagnetic coupling dominated their physical behavior with doping concentrations beyond 12 at%. Such experimental phenomenon was in very good agreement with associated first principle calculations. The ferromagnetic-like ordering originates from the breaking of equivalence between two different Mn-O octahedrals in ?-MnO2 due to the filling of alkaline ions in the tunnels. Both small charge transfer and lattice distortion play important roles in the ferromagnetic ordering. PMID:25766870

Tseng, Li-Ting; Lu, Yunhao; Fan, Hai Ming; Wang, Yiren; Luo, Xi; Liu, Tao; Munroe, Paul; Li, Sean; Yi, Jiabao

2015-01-01

51

Magnetic properties in ?-MnO2 doped with alkaline elements  

NASA Astrophysics Data System (ADS)

?-MnO2 nanotubes were fabricated using a hydrothermal technique. Li, Na and K ions were introduced into MnO2 nanotubes to tailor their magnetic properties. It was found that with a doping concentration lower than 12 at%, the nanotubes showed ferromagnetic-like ordering at low temperature (<50 K), while antiferromagnetic coupling dominated their physical behavior with doping concentrations beyond 12 at%. Such experimental phenomenon was in very good agreement with associated first principle calculations. The ferromagnetic-like ordering originates from the breaking of equivalence between two different Mn-O octahedrals in ?-MnO2 due to the filling of alkaline ions in the tunnels. Both small charge transfer and lattice distortion play important roles in the ferromagnetic ordering.

Tseng, Li-Ting; Lu, Yunhao; Fan, Hai Ming; Wang, Yiren; Luo, Xi; Liu, Tao; Munroe, Paul; Li, Sean; Yi, Jiabao

2015-03-01

52

Magnetic Properties of MnO2 Shrimps-Like Nanostructures Synthesized by Hydrothermal Route  

NASA Astrophysics Data System (ADS)

In this paper, we report the field-dependent magnetization (M-H) and temperature-dependent magnetization (M-T) properties of hexagonal MnO2 shrimps-like nanostructures which have been successfully synthesized by hydrothermal route using KMnO4 and HNO3 as precursors. The magnetic properties were characterized by vibrating sample magnetometer (VSM). Field-dependent magnetization (M-H) measured at 300 K exhibit paramagnetic nature of MnO2 nanostructures, while an antiferromagnetic component is observed for the as-prepared product at 55 K. The Néel temperature (TN) is calculated as 89 K by plotting temperature-dependent magnetization (M-T) curve for the as-prepared MnO2 nanostructures. X-ray photoelectron spectroscopy (XPS) is employed to calculate the binding energies of Mn (2p3/2, 2p1/2) and O (1s) observed in the spectrum.

Toufiq, Arbab Mohammad; Wang, Fengping; Javed, Qurat-Ul-Ain; Li, Yan

2013-10-01

53

First-principles study of magnetism in spinel MnO2 Dane Morgan and Billie Wang  

E-print Network

First-principles study of magnetism in spinel MnO2 Dane Morgan and Billie Wang Department to calculate the ground state, transition tem- perature, and thermodynamic properties of magnetic excitations in spinel MnO2 . The magnetic interactions are mapped onto a Heisenberg model whose exchange interactions

Ceder, Gerbrand

54

Enhancement of supercapacitance property of electrochemically deposited MnO2 thin films grown in acidic medium  

NASA Astrophysics Data System (ADS)

In this communication we present supercapacitance property of MnO2 thin-films which are fabricated on stainless steel (SS) substrate by electro-deposition method carried out in different pH of the electrolyte. A significant improvement of the device performance of acid mediated grown (AMG) MnO2 over normal MnO2 (grown in neutral medium) has been achieved. We have also investigated role of interfacial structure on the internal resistance of the device material. AMG MnO2 film exhibits superior device performance with specific capacitance of 652 F/g which is 2 times better than that obtained in normal MnO2 and also energy density of 90.69 Wh/kg.

Jana, S. K.; Rao, V. P.; Banerjee, S.

2014-02-01

55

Dissolution kinetics of colloidal manganese dioxide in aqueous hydrochloric acid at 298 K  

NASA Astrophysics Data System (ADS)

The dissolution kinetics of colloidal MnO2 in aqueous hydrochloric acid is studied at 298 K by spectrophotometric methods. The decay profile of MnO2 monitored by measuring absorbance due to MnO2 at 390 nm was exponential. As the hydrochloric acid concentration was increased from 1.26 to 5.03 M, the dissolution rate of MnO2 to Mn(II) species decreased. The reaction followed fractional order kinetics with respect both to MnO2 and HCl concentrations. The average oxidation state approached a value of +2 indicating that HCl reduced Mn-species to Mn(II) species. Mechanism based on the observed kinetics has been proposed and discussed.

Islam, Md. Aminul; Rahman, M. Muhibur

2015-04-01

56

Aluminum manganese oxides with mixed crystal structure: high-energy-density cathodes for rechargeable sodium batteries.  

PubMed

We report a new discovery for enhancing the energy density of manganese oxide (Nax MnO2 ) cathode materials for sodium rechargeable batteries by incorporation of aluminum. The Al incorporation results in NaAl(0.1) Mn(0.9) O2 with a mixture of tunnel and layered crystal structures. NaAl(0.1) Mn(0.9) O2 shows a much higher initial discharge capacity and superior cycling performance compared to pristine Na(0.65) MnO2 . We ascribe this enhancement in performance to the formation of a new orthorhombic layered NaMnO2 phase merged with a small amount of tunnel Na(0.44) MnO2 phase in NaAl(0.1) Mn(0.9) O2 , and to improvements in the surface stability of the NaAl(0.1) Mn(0.9) O2 particles caused by the formation of Al-O bonds on their surfaces. Our findings regarding the phase transformation and structure stabilization induced by incorporation of aluminum, closely related to the structural analogy between orthorhombic Na(0.44) MnO2 and NaAl(0.1) Mn(0.9) O2 , suggest a strategy for achieving sodium rechargeable batteries with high energy density and stability. PMID:24797956

Han, Dong-Wook; Ku, Jun-Hwan; Kim, Ryoung-Hee; Yun, Dong-Jin; Lee, Seok-Soo; Doo, Seok-Gwang

2014-07-01

57

Advanced Small Rechargeable Batteries  

NASA Technical Reports Server (NTRS)

Lithium-based units offer highest performance. Paper reviews status of advanced, small rechargeable batteries. Covers aqueous systems including lead/lead dioxide, cadmium/nickel oxide, hydrogen/nickel oxide, and zinc/nickel oxide, as well as nonaqueous systems. All based on lithium anodes, nonaqueous systems include solid-cathode cells (lithium/molybdenum disulfide, lithium/titanium disulfide, and lithium/vanadium oxide); liquid-cathode cells (lithium/sulfur dioxide cells); and new category, lithium/polymer cells.

Halpert, Gerald

1989-01-01

58

Enhanced Tolerance to Stretch-Induced Performance Degradation of Stretchable MnO2-Based Supercapacitors.  

PubMed

The performance of many stretchable electronics, such as energy storage devices and strain sensors, is highly limited by the structural breakdown arising from the stretch imposed. In this article, we focus on a detailed study on materials matching between functional materials and their conductive substrate, as well as enhancement of the tolerance to stretch-induced performance degradation of stretchable supercapacitors, which are essential for the design of a stretchable device. It is revealed that, being widely utilized as the electrode material of the stretchable supercapacitor, metal oxides such as MnO2 nanosheets have serious strain-induced performance degradation due to their rigid structure. In comparison, with conducting polymers like a polypyrrole (PPy) film as the electrochemically active material, the performance of stretchable supercapacitors can be well preserved under strain. Therefore, a smart design is to combine PPy with MnO2 nanosheets to achieve enhanced tolerance to strain-induced performance degradation of MnO2-based supercapacitors, which is realized by fabricating an electrode of PPy-penetrated MnO2 nanosheets. The composite electrodes exhibit a remarkable enhanced tolerance to strain-induced performance degradation with well-preserved performance over 93% under strain. The detailed morphology and electrochemical impedance variations are investigated for the mechanism analyses. Our work presents a systematic investigation on the selection and matching of electrode materials for stretchable supercapacitors to achieve high performance and great tolerance to strain, which may guide the selection of functional materials and their substrate materials for the next-generation of stretchable electronics. PMID:25569836

Huang, Yan; Huang, Yang; Meng, Wenjun; Zhu, Minshen; Xue, Hongtao; Lee, Chun-Sing; Zhi, Chunyi

2015-02-01

59

In situ formation of ?-MnO2 nanowires as catalyst for sodium-air batteries  

NASA Astrophysics Data System (ADS)

Using a microwave-assisted path, MnO2 structures were prepared to be used as catalyst material in room-temperature-operated sodium-air cells. The electrochemical cells are prepared using a dry coating step (Laser Induced Forward Transfer), i.e. without organic solvents. Due to a novel formulation for an electrolyte, the electrochemical stability and performance of as-prepared electrodes is very high (1215 Ah/kg specific charge).

Rosenberg, Sarah; Hintennach, Andreas

2015-01-01

60

Effect of doping MnO 2 on magnetic properties for M-type barium ferrite  

Microsoft Academic Search

The crystalline structure and magnetic properties of M-type barium ferrite doped with small amounts of MnO2 (0, 0.25, 0.5, 0.75, 1.0, 1.5, and 2.0wt%, respectively) have been investigated by means of XRD, SEM and VSM. The results show that the crystalline structures of barium ferrite are still M-type hexagonal structure and Mn ions are distributed homogeneously in both the grains

Xin Zhang; Yuping Duan; Hongtao Guan; Shunhua Liu; Bin Wen

2007-01-01

61

Capture and release of cancer cells using electrospun etchable MnO2 nanofibers integrated in microchannels  

NASA Astrophysics Data System (ADS)

This paper introduces a cancer cell capture/release microchip based on the self-sacrificed MnO2 nanofibers. Through electrospinning, lift-off and soft-lithography procedures, MnO2 nanofibers are tactfully fabricated in microchannels to implement enrichment and release of cancer cells in liquid samples. The MnO2 nanofiber net which mimics the extra cellular matrix can lead to high capture ability with the help of a cancer cell-specific antibody bio-conjugation. Subsequently, an effective and friendly release method is carried out by using low concentration of oxalic acid to dissolve the MnO2 nanofiber substrate while keeping high viability of those released cancer cells at the same time. It is conceivable that our microchip may have potentials in realizing biomedical analysis of circulating tumor cells for biological and clinical researches in oncology.

Liu, Hui-qin; Yu, Xiao-lei; Cai, Bo; You, Su-jian; He, Zhao-bo; Huang, Qin-qin; Rao, Lang; Li, Sha-sha; Liu, Chang; Sun, Wei-wei; Liu, Wei; Guo, Shi-shang; Zhao, Xing-zhong

2015-03-01

62

MnO2 Nanorods Intercalating Graphene Oxide/Polyaniline Ternary Composites for Robust High-Performance Supercapacitors  

PubMed Central

New ternary composites of MnO2 nanorods, polyaniline (PANI) and graphene oxide (GO) have been prepared by a two-step process. The 100?nm-long MnO2 nanorods with a diameter ~20?nm are conformably coated with PANI layers and fastened between GO layers. The MnO2 nanorods incorporated ternary composites electrode exhibits significantly increased specific capacitance than PANI/GO binary composite in supercapacitors. The ternary composite with 70% MnO2 exhibits a highest specific capacitance reaching 512?F/g and outstanding cycling performance, with ~97% capacitance retained over 5000 cycles. The ternary composite approach offers an effective solution to enhance the device performance of metal-oxide based supercapacitors for long cycling applications. PMID:24769835

Han, Guangqiang; Liu, Yun; Zhang, Lingling; Kan, Erjun; Zhang, Shaopeng; Tang, Jian; Tang, Weihua

2014-01-01

63

Preparation and electrochemistry of one-dimensional nanostructured MnO 2/PPy composite for electrochemical capacitor  

NASA Astrophysics Data System (ADS)

One-dimensional nanostructured manganese dioxide/polypyrrole (MnO 2/PPy) composite was prepared by in situ chemical oxidation polymerization of pyrrole in the host of inorganic matrix of MnO 2, using complex of methyl orange (MO)/FeCl 3 as a reactive self-degraded soft-template. The morphology and structure of the composite were characterized by infrared spectroscopy (IR) X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the MnO 2/PPy composite consists of ?-MnO 2 and PPy with nanotube-like structure. Electrochemical properties of the composite demonstrated the material showed good electrochemical reversibility after 500 charge-discharge cycles in the potential range of -0.4 to 0.6 V, the tube-like nanocomposite has the potential application in electrochemical capacitor.

Li, Juan; Cui, Li; Zhang, Xiaogang

2010-04-01

64

Process dependent graphene-wrapped plate-like MnO2 nanospheres for high performance supercapacitor  

NASA Astrophysics Data System (ADS)

Two kinds of MnO2/graphene nanocomposites (M1 and M2) were synthesized by two different reaction procedures. M1 was synthesized as follows: the plate-like MnO2/graphene nanocomposite was obtained by using hydrazine reduction of MnO2/graphene oxide. M2 was formed as follows: the plate-like MnO2 nanospheres was synthesized on the graphene nanosheet which was reduced by hydrazine reduction of graphene oxide. The M1 have a good electrochemical performance and the average capacitance is as high as 250.6 F g-1 at 1 A g-1 in 1 mol L-1 Na2SO4 electrolyte, which is higher than that of the M2 (206.8 F g-1).

Liu, Chunliang; Gui, Dayong; Liu, Jianhong

2014-10-01

65

Rationally designed hierarchical MnO2-shell/ZnO-nanowire/carbon-fabric for high-performance supercapacitor electrodes  

NASA Astrophysics Data System (ADS)

High-performance supercapacitor electrodes with a novel hierarchical structure of MnO2/ZnO/carbon-fabric were rationally designed, and prepared by a simple three-step-solution method. The design comprises ZnO nanowires radially grown on each micron-size fiber of a carbon-fabric electrode, with a thin MnO2 shell on each ZnO nano-core. This multi-scale hierarchical structure yields: (a) high specific area of pseudo-capacitive MnO2 to maximize specific capacitance; (b) effective MnO2-electrolyte interface to facilitate fast charging/discharging; and (c) conductive MnO2-ZnO-electrode path to reduce energy loss. In addition, the overall capacitor performance is optimized by choosing proper thickness of MnO2 shell and aspect ratio of ZnO nano-core. The design was realized and validated with the development of a simple three-step-solution method: (a) radial deposition of nano-ZnO on carbon fabric; (b) coating ZnO by a thin layer of carbon; and (c) reduction of MnO4- and replacement of this carbon overlayer by MnO2. With this design and method, high specific capacitance of 886 F g-1 was found from electrodes with 5 nm MnO2 on ZnO having an average diameter of 50 nm and aspect ratio of 30. These samples showed specific energy of 16 Wh kg-1 and specific power of 27 kW kg-1 at current density of 20 mA cm-2, and good long-term cycling stability.

Yang, Q.; Zhang, X. T.; Zhang, M. Y.; Gao, Y.; Gao, H.; Liu, X. C.; Liu, H.; Wong, K. W.; Lau, W. M.

2014-12-01

66

Aggregation kinetics of manganese dioxide colloids in aqueous solution: influence of humic substances and biomacromolecules.  

PubMed

In this work, the early stage aggregation kinetics of manganese dioxide (MnO2) colloids in aqueous solution and the effects of constituents of natural organic matter (i.e., Suwannee River fulvic acid (SRFA), Suwannee River humic acid (SRHA), alginate, and bovine serum albumin (BSA)) were investigated by time-resolved dynamic light scattering. MnO2 colloids were significantly aggregated in the presence of monovalent and divalent cations. The critical coagulation concentrations were 28, 0.8, and 0.45 mM for NaNO3, Mg(NO3)2, and Ca(NO3)2, respectively. The Hamaker constant of MnO2 colloids in aqueous solution was 7.84 × 10(-20) J. All the macromolecules tested slowed MnO2 colloidal aggregation rates greatly. The steric repulsive forces, originated from organic layers adsorbed on MnO2 colloidal surfaces, may be mainly responsible for their stabilizing effects. However, the complexes formed by alginate and Ca(2+) (>5 mM) might play a bridging role and thus enhanced MnO2 colloidal aggregation instead. These results may be important for assessing the fate and transport of MnO2 colloids and associated contaminants. PMID:23947796

Huangfu, Xiaoliu; Jiang, Jin; Ma, Jun; Liu, Yongze; Yang, Jing

2013-09-17

67

Hierarchical ?-MnO2 nanowires@Ni1-x Mnx Oy nanoflakes core-shell nanostructures for supercapacitors.  

PubMed

A facile two-step solution-phase method has been developed for the preparation of hierarchical ?-MnO2 nanowires@Ni1-x Mnx Oy nanoflakes core-shell nanostructures. Ultralong ?-MnO2 nanowires were synthesized by a hydrothermal method in the first step. Subsequently, Ni1-x Mnx Oy nanoflakes were grown on ?-MnO2 nanowires to form core-shell nanostructures using chemical bath deposition followed by thermal annealing. Both solution-phase methods can be easily scaled up for mass production. We have evaluated their application in supercapacitors. The ultralong one-dimensional (1D) ?-MnO2 nanowires in hierarchical core-shell nanostructures offer a stable and efficient backbone for charge transport; while the two-dimensional (2D) Ni1-x Mnx Oy nanoflakes on ?-MnO2 nanowires provide high accessible surface to ions in the electrolyte. These beneficial features enable the electrode with high capacitance and reliable stability. The capacitance of the core-shell ?-MnO2 @Ni1-x Mnx Oy nanostructures (x = 0.75) is as high as 657 F g(-1) at a current density of 250 mA g(-1) , and stable charging-discharging cycling over 1000 times at a current density of 2000 mA g(-1) has been realized. PMID:24711308

Wang, Hsin-Yi; Xiao, Fang-Xing; Yu, Le; Liu, Bin; Lou, Xiong Wen David

2014-08-01

68

MnO2 prepared by hydrothermal method and electrochemical performance as anode for lithium-ion battery  

PubMed Central

Two ?-MnO2 crystals with caddice-clew-like and urchin-like morphologies are prepared by the hydrothermal method, and their structure and electrochemical performance are characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), galvanostatic cell cycling, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). The morphology of the MnO2 prepared under acidic condition is urchin-like, while the one prepared under neutral condition is caddice-clew-like. The identical crystalline phase of MnO2 crystals is essential to evaluate the relationship between electrochemical performances and morphologies for lithium-ion battery application. In this study, urchin-like ?-MnO2 crystals with compact structure have better electrochemical performance due to the higher specific capacity and lower impedance. We find that the relationship between electrochemical performance and morphology is different when MnO2 material used as electrochemical supercapacitor or as anode of lithium-ion battery. For lithium-ion battery application, urchin-like MnO2 material has better electrochemical performance. PMID:24982603

2014-01-01

69

Nanoflaky MnO2/functionalized carbon nanotubes for supercapacitors: an in situ X-ray absorption spectroscopic investigation.  

PubMed

The surfaces of acid- and amine-functionalized carbon nanotubes (C-CNT and N-CNT) were decorated with MnO2 nanoflakes as supercapacitors by a spontaneous redox reaction. C-CNT was found to have a lower edge plane structure and fewer defect sites than N-CNT. MnO2/C-CNT with a highly developed surface area exhibited favorable electrochemical performance. To determine the atomic/electronic structures of the MnO2/functionalized CNTs (MnO2/C-CNT and MnO/N-CNT) during the charge/discharge process, in situ X-ray absorption spectroscopy (XAS) measurements were made at the Mn K-edge. Both C-CNT and N-CNT are highly conductive. The effect of the scan rate on the capacitance behavior was also examined, revealing that the ?* state of CNT and the size of the tunnels in pseudo-capacitor materials (which facilitate conduction and the transport of electrolyte ions) are critical for the capacitive performance, and their role depends on the scan rate. In the slow charge/discharge process, MnO2/N-CNT has a more symmetrical rectangular cyclic voltammetry (CV) curve. In the fast charge/discharge process, MnO2/C-CNT with a highly developed surface provides fast electronic and ionic channels that support a reversible faradaic redox reaction between MnO2 nanoflakes and the electrolyte, significantly enhancing its capacitive performance over that of MnO2/N-CNT. The MnO2/C-CNT architecture has great potential for supercapacitor applications. The information that was obtained herein helps to elucidate CNT surface modification and the design of the MnO2/functionalized CNT interface with a view for the further development of supercapacitors. This work, and especially the combination of CV with in situ XAS measurements, will be of value to readers with an interest in nanomaterial, nanotechnology and their applications in energy storage. PMID:25511126

Chang, Han-Wei; Lu, Ying-Rui; Chen, Jeng-Lung; Chen, Chi-Liang; Lee, Jyh-Fu; Chen, Jin-Ming; Tsai, Yu-Chen; Chang, Chien-Min; Yeh, Ping-Hung; Chou, Wu-Ching; Liou, Ya-Hsuan; Dong, Chung-Li

2015-02-01

70

A facile one-pot hydrothermal synthesis of ?-MnO2 nanopincers and their catalytic degradation of methylene blue  

NASA Astrophysics Data System (ADS)

Branched ?-MnO2 bipods with novel nanopincer morphology were prepared by a facile one-pot hydrothermal method via a redox reaction between NaClO3 and MnSO4 in sulfuric acid solution without using any surfactants or templates. The products were characterized in detail by various techniques including X-ray powder diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, surface area analyzer, field emission scanning electron microscopy and transmission electron microscopy. Results show that the obtained ?-MnO2 nanopincers consist of two sharp nanorods with a diameter of 100-200 nm and a length of 1-2 ?m. The concentration of H2SO4 solution plays an important role in controlling the crystal phase and morphology of the final product. A possible formation mechanism for the ?-MnO2 nanopincers was proposed. Moreover, these ?-MnO2 nanostructures exhibited better catalytic performance than the commercial MnO2 particles to decompose methyl blue (MB) in the presence of H2O2.

Cheng, Gao; Yu, Lin; Lin, Ting; Yang, Runnong; Sun, Ming; Lan, Bang; Yang, Lili; Deng, Fangze

2014-09-01

71

Hierarchical MnO2/SnO2 heterostructures for a novel free-standing ternary thermite membrane.  

PubMed

We report the synthesis of a novel hierarchical MnO2/SnO2 heterostructures via a hydrothermal method. Secondary SnO2 nanostructure grows epitaxially on the surface of MnO2 backbones without any surfactant, which relies on the minimization of surface energy and interfacial lattice mismatch. Detailed investigations reveal that the cover density and morphology of the SnO2 nanostructure can be tailored by changing the experimental parameter. Moreover, we demonstrate a bottom-up method to produce energetic nanocomposites by assembling nanoaluminum (n-Al) and MnO2/SnO2 hierarchical nanostructures into a free-standing MnO2/SnO2/n-Al ternary thermite membrane. This assembled approach can significantly reduce diffusion distances and increase their intimacy between the components. Different thermite mixtures were investigated to evaluate the corresponding activation energies using DSC techniques. The energy performance of the ternary thermite membrane can be manipulated through different components of the MnO2/SnO2 heterostructures. Overall, our work may open a new route for new energetic materials. PMID:23905515

Yang, Yong; Zhang, Zhi-Cheng; Wang, Peng-Peng; Zhang, Jing-Chao; Nosheen, Farhat; Zhuang, Jing; Wang, Xun

2013-08-19

72

Facile preparation of three-dimensional multilayer porous MnO2/reduced graphene oxide composite and its supercapacitive performance  

NASA Astrophysics Data System (ADS)

Three-dimensional (3D) multilayer porous MnO2/reduced graphene oxide composites are coated on a nickel foam substrate (denoted as MnO2/R-GO@Ni-foam) by a facile and scalable spray method following by low temperature annealing. The composite electrodes are characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. The content of MnO2 in the MnO2/R-GO@Ni-foam composites is determined by thermal gravimetric analysis. The supercapacitive performance of the composite electroides is investigated by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The results show that the MnO2/R-GO@Ni-foam composite displays a high specific capacitance of 267 F g-1 at 0.25 A g-1 and excellent capacitance retention of 89.5% after 1000 cycles. This study provides a facile way for the preparation of composite electrodes for high-performance supercapacitor.

Li, Yiju; Wang, Guiling; Ye, Ke; Cheng, Kui; Pan, Yue; Yan, Peng; Yin, Jinling; Cao, Dianxue

2014-12-01

73

Nanoflaky MnO2/functionalized carbon nanotubes for supercapacitors: an in situ X-ray absorption spectroscopic investigation  

NASA Astrophysics Data System (ADS)

The surfaces of acid- and amine-functionalized carbon nanotubes (C-CNT and N-CNT) were decorated with MnO2 nanoflakes as supercapacitors by a spontaneous redox reaction. C-CNT was found to have a lower edge plane structure and fewer defect sites than N-CNT. MnO2/C-CNT with a highly developed surface area exhibited favorable electrochemical performance. To determine the atomic/electronic structures of the MnO2/functionalized CNTs (MnO2/C-CNT and MnO/N-CNT) during the charge/discharge process, in situ X-ray absorption spectroscopy (XAS) measurements were made at the Mn K-edge. Both C-CNT and N-CNT are highly conductive. The effect of the scan rate on the capacitance behavior was also examined, revealing that the ?* state of CNT and the size of the tunnels in pseudo-capacitor materials (which facilitate conduction and the transport of electrolyte ions) are critical for the capacitive performance, and their role depends on the scan rate. In the slow charge/discharge process, MnO2/N-CNT has a more symmetrical rectangular cyclic voltammetry (CV) curve. In the fast charge/discharge process, MnO2/C-CNT with a highly developed surface provides fast electronic and ionic channels that support a reversible faradaic redox reaction between MnO2 nanoflakes and the electrolyte, significantly enhancing its capacitive performance over that of MnO2/N-CNT. The MnO2/C-CNT architecture has great potential for supercapacitor applications. The information that was obtained herein helps to elucidate CNT surface modification and the design of the MnO2/functionalized CNT interface with a view for the further development of supercapacitors. This work, and especially the combination of CV with in situ XAS measurements, will be of value to readers with an interest in nanomaterial, nanotechnology and their applications in energy storage.The surfaces of acid- and amine-functionalized carbon nanotubes (C-CNT and N-CNT) were decorated with MnO2 nanoflakes as supercapacitors by a spontaneous redox reaction. C-CNT was found to have a lower edge plane structure and fewer defect sites than N-CNT. MnO2/C-CNT with a highly developed surface area exhibited favorable electrochemical performance. To determine the atomic/electronic structures of the MnO2/functionalized CNTs (MnO2/C-CNT and MnO/N-CNT) during the charge/discharge process, in situ X-ray absorption spectroscopy (XAS) measurements were made at the Mn K-edge. Both C-CNT and N-CNT are highly conductive. The effect of the scan rate on the capacitance behavior was also examined, revealing that the ?* state of CNT and the size of the tunnels in pseudo-capacitor materials (which facilitate conduction and the transport of electrolyte ions) are critical for the capacitive performance, and their role depends on the scan rate. In the slow charge/discharge process, MnO2/N-CNT has a more symmetrical rectangular cyclic voltammetry (CV) curve. In the fast charge/discharge process, MnO2/C-CNT with a highly developed surface provides fast electronic and ionic channels that support a reversible faradaic redox reaction between MnO2 nanoflakes and the electrolyte, significantly enhancing its capacitive performance over that of MnO2/N-CNT. The MnO2/C-CNT architecture has great potential for supercapacitor applications. The information that was obtained herein helps to elucidate CNT surface modification and the design of the MnO2/functionalized CNT interface with a view for the further development of supercapacitors. This work, and especially the combination of CV with in situ XAS measurements, will be of value to readers with an interest in nanomaterial, nanotechnology and their applications in energy storage. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr06439a

Chang, Han-Wei; Lu, Ying-Rui; Chen, Jeng-Lung; Chen, Chi-Liang; Lee, Jyh-Fu; Chen, Jin-Ming; Tsai, Yu-Chen; Chang, Chien-Min; Yeh, Ping-Hung; Chou, Wu-Ching; Liou, Ya-Hsuan; Dong, Chung-Li

2015-01-01

74

First-principles calculations of oxygen vacancy formation and metallic behavior at a ?-MnO2 grain boundary.  

PubMed

Nanostructured MnO2 is renowned for its excellent energy storage capability and high catalytic activity. While the electronic and structural properties of MnO2 surfaces have received significant attention, the properties of the grain boundaries (GBs) and their contribution to the electrochemical performance of the material remains unknown. Through density functional theory (DFT) calculations, the structure and electronic properties of the ?-MnO2 ? 5(210)/[001] GB are studied. Our calculations show this low energy GB has a significantly reduced band gap compared to the pristine material and that the formation of oxygen vacancies produces spin-polarized states that further reduce the band gap. Calculated formation energies of oxygen vacancy defects and Mn reduction at the GB core are all lower than the equivalent bulk value and in some cases lower than values recently calculated for ?-MnO2 surfaces. Oxygen vacancy formation is also shown to produce a metallic behavior at the GB with defect charge distributed over a number of oxygen and manganese sites. The low energies of oxygen defect formation and the potential creation of conductive GB pathways are likely to be important to the electrochemical performance of ?-MnO2. PMID:25559707

Dawson, James A; Chen, Hungru; Tanaka, Isao

2015-01-28

75

Activation of a MnO2 cathode by water-stimulated Mg(2+) insertion for a magnesium ion battery.  

PubMed

Magnesium batteries have been considered to be one of the promising beyond lithium ion technologies due to magnesium's abundance, safety, and high volumetric capacity. However, very few materials show reversible performance as a cathode in magnesium ion systems. We present herein the best reported cycling performances of MnO2 as a magnesium battery cathode material. We show that the previously reported poor Mg(2+) insertion/deinsertion capacities in MnO2 can be greatly improved by synthesizing self-standing nanowires and introducing a small amount of water molecules into the electrolyte. Electrochemical and elemental analysis results revealed that the magnitude of Mg(2+) insertion into MnO2 highly depends on the ratio between water molecules and Mg(2+) ions present in the electrolyte and the highest Mg(2+) insertion capacity was observed at a ratio of 6H2O/Mg(2+) in the electrolyte. We demonstrate for the first time, that MnO2 nanowire electrode can be "activated" for Mg(2+) insertion/deinsertion by cycling in water containing electrolyte resulting in enhanced reversible Mg(2+) insertion/deinsertion even with the absence of water molecules. The MnO2 nanowire electrode cycled in dry Mg electrolyte after activation in water-containing electrolyte showed an initial capacity of 120 mA h g(-1) at a rate of 0.4 C and maintained 72% of its initial capacity after 100 cycles. PMID:25608277

Song, Jaehee; Noked, Malakhi; Gillette, Eleanor; Duay, Jonathon; Rubloff, Gary; Lee, Sang Bok

2015-02-01

76

Performance modulation of ?-MnO2 nanowires by crystal facet engineering.  

PubMed

Modulation of material physical and chemical properties through selective surface engineering is currently one of the most active research fields, aimed at optimizing functional performance for applications. The activity of exposed crystal planes determines the catalytic, sensory, photocatalytic, and electrochemical behavior of a material. In the research on nanomagnets, it opens up new perspectives in the fields of nanoelectronics, spintronics, and quantum computation. Herein, we demonstrate controllable magnetic modulation of ?-MnO2 nanowires, which displayed surface ferromagnetism or antiferromagnetism, depending on the exposed plane. First-principles density functional theory calculations confirm that both Mn- and O-terminated ?-MnO2 (1 1 0) surfaces exhibit ferromagnetic ordering. The investigation of surface-controlled magnetic particles will lead to significant progress in our fundamental understanding of functional aspects of magnetism on the nanoscale, facilitating rational design of nanomagnets. Moreover, we approved that the facet engineering pave the way on designing semiconductors possessing unique properties for novel energy applications, owing to that the bandgap and the electronic transport of the semiconductor can be tailored via exposed surface modulations. PMID:25758232

Li, Wenxian; Cui, Xiangyuan; Zeng, Rong; Du, Guodong; Sun, Ziqi; Zheng, Rongkun; Ringer, Simon P; Dou, Shi Xue

2015-01-01

77

Synthesis and characterization of hierarchically structured mesoporous MnO 2 and Mn 2O 3  

NASA Astrophysics Data System (ADS)

Hierarchically structured mesoporous MnO 2 with high surface area was prepared by a facile precursor route. Well-defined morphological manganese oxalate, synthesized by adding L-lysine via a hydrothermal method, was used as precursor. Mesoporous amorphous MnO 2 with high Brunauer-Emmett-Teller (BET) surface area (340 m 2/g) and mesoporous Mn 2O 3 composed of nano-crystals (BET surface area 188 m 2/g) were obtained by selective calcination of the oxalate precursor at 330 °C and 400 °C, respectively. Thermogravimetric and differential thermal analyses (TG-DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N 2-sorption analysis and X-ray photoelectron spectroscopy (XPS) were used to characterize the structure and property of products. Cyclic voltammetry (CV) and charge-discharge measurements were used to preliminarily study the electrochemical performance of the products. The range of pH value (about 5.0-7.0) in the synthesis process is apt to prepare the hierarchical structured manganese dioxide. Other types of amino acids were also employed as the crystallization modifiers and different morphologies of manganese dioxides were obtained.

Liu, Mi; Zhang, Gui-Jun; Shen, Zhu-Rui; Sun, Ping-Chuan; Ding, Da-Tong; Chen, Tie-Hong

2009-01-01

78

Performance modulation of ?-MnO2 nanowires by crystal facet engineering  

PubMed Central

Modulation of material physical and chemical properties through selective surface engineering is currently one of the most active research fields, aimed at optimizing functional performance for applications. The activity of exposed crystal planes determines the catalytic, sensory, photocatalytic, and electrochemical behavior of a material. In the research on nanomagnets, it opens up new perspectives in the fields of nanoelectronics, spintronics, and quantum computation. Herein, we demonstrate controllable magnetic modulation of ?-MnO2 nanowires, which displayed surface ferromagnetism or antiferromagnetism, depending on the exposed plane. First-principles density functional theory calculations confirm that both Mn- and O-terminated ?-MnO2 (1 1 0) surfaces exhibit ferromagnetic ordering. The investigation of surface-controlled magnetic particles will lead to significant progress in our fundamental understanding of functional aspects of magnetism on the nanoscale, facilitating rational design of nanomagnets. Moreover, we approved that the facet engineering pave the way on designing semiconductors possessing unique properties for novel energy applications, owing to that the bandgap and the electronic transport of the semiconductor can be tailored via exposed surface modulations. PMID:25758232

Li, Wenxian; Cui, Xiangyuan; Zeng, Rong; Du, Guodong; Sun, Ziqi; Zheng, Rongkun; Ringer, Simon P.; Dou, Shi Xue

2015-01-01

79

Performance modulation of ?-MnO2 nanowires by crystal facet engineering  

NASA Astrophysics Data System (ADS)

Modulation of material physical and chemical properties through selective surface engineering is currently one of the most active research fields, aimed at optimizing functional performance for applications. The activity of exposed crystal planes determines the catalytic, sensory, photocatalytic, and electrochemical behavior of a material. In the research on nanomagnets, it opens up new perspectives in the fields of nanoelectronics, spintronics, and quantum computation. Herein, we demonstrate controllable magnetic modulation of ?-MnO2 nanowires, which displayed surface ferromagnetism or antiferromagnetism, depending on the exposed plane. First-principles density functional theory calculations confirm that both Mn- and O-terminated ?-MnO2 (1 1 0) surfaces exhibit ferromagnetic ordering. The investigation of surface-controlled magnetic particles will lead to significant progress in our fundamental understanding of functional aspects of magnetism on the nanoscale, facilitating rational design of nanomagnets. Moreover, we approved that the facet engineering pave the way on designing semiconductors possessing unique properties for novel energy applications, owing to that the bandgap and the electronic transport of the semiconductor can be tailored via exposed surface modulations.

Li, Wenxian; Cui, Xiangyuan; Zeng, Rong; Du, Guodong; Sun, Ziqi; Zheng, Rongkun; Ringer, Simon P.; Dou, Shi Xue

2015-03-01

80

Analysis of electrochemical mechanism of coprecipitated nano-Ag 4Bi 2O 5 as super high charge-discharge rate cathode materials for aqueous rechargeable battery  

Microsoft Academic Search

Nano Ag4Bi2O5 as a novel cathode material of rechargeable alkaline batteries was successfully synthesized by precise control of precipitation reaction. KOH solution was used as precipitant and a mixture of AgNO3 and Bi(NO3)3 as Ag-Bi source. The experimental results indicate that concentration of KOH, reaction temperature and PH value have the effects on the structure and electrochemical property of the

Junqing Pan; Qian Wang; Yanzhi Sun; Zihao Wang

81

The rate of sulfide oxidation by ?MnO 2 in seawater  

NASA Astrophysics Data System (ADS)

The rate of oxidation of hydrogen sulfide by manganese dioxide in seawater was determined as a function of pH (2.0-9.0), temperature (5-45°C), and ionic strength (0-4 M). The overall rate constant, k, in seawater at pH = 8.17 was found to be first order with respect to both sulfide and manganese dioxide: - d[H 2S] T/dt = k[H 2S] ?[MnO 2] . The rate constant, k, for seawater (S = 35.8, pH = 8.17) at 25°C was found to be 436 M -1 min -1, or 0.0244 m -2 1 min -1 when [MnO 2] is expressed in surface area (m 2/L). The energies of activation were found to be 14 ± 1 KJ mol -1 and 10 ± 1 KJ mol -1, respectively, for pH = 8.2 and pH = 5.0 in seawater (S = 35). The rate increased from pH 2.0 to a maximum at a pH of about 5.0 and decreased at higher pH. This pH dependence was attributed to formation of a surface complex between >MnO - and H 2S. As the concentration of HS - increases above pH = 5 the rate of the reaction decreases. The rate of sulfide oxidation by MnO 2 is not strongly dependent on ionic strength. The rates in 0.57 M NaCl were found to be slightly higher than the rates in seawater. Measurements made in solutions of the major sea salts indicated that Ca 2+ and Mg 2+ caused the rates to decrease, apparently by absorbing on the surface of manganese dioxide. Measurements made in artificial seawater (Na +, Mg 2+, Ca 2+, Cl -, and SO 2-4) were found to be in good agreement with the measurements in actual seawater. Phosphate was found to inhibit the reaction significantly.

Yao, Wensheng; Millero, Frank J.

1993-07-01

82

Microstructure and ferroelectric properties of MnO2-doped bismuth-layer ,,Ca,Sr...Bi4Ti4O15 ceramics  

E-print Network

Microstructure and ferroelectric properties of MnO2-doped bismuth-layer ,,Ca,Sr...Bi4Ti4O15 September 2005 We have studied the microstructures and ferroelectric properties of MnO2-doped bismuth and fatigue-free and lead-free nature, Aurivillius bismuth-layer structure compounds BLSCs are widely used

Cao, Wenwu

83

Recovery of MnO2 from a spent alkaline battery leach solution via ozone treatment  

NASA Astrophysics Data System (ADS)

This work investigates the reaction rate of Mn(II) to generate solid manganese dioxide (MnO2) as a function of the gaseous ozone mass flow rate (27.5-77 g h-1). The experimental studies were carried out in a semi-continuous reactor, using a synthetic solution (300 mL of 1 M H2SO4 with 6000 ppm of Mn(II) added as MnSO4) that simulated the composition of an acid leaching solution from spent alkaline battery material (SBM). It was observed that at 1.3-1.45 V/SHE and pH < 1.0 a selective formation of MnO2 powder was obtained; at values greater than 1.45 V/SHE, permanganate ion (MnO41-) was formed. On the other hand, a linear relation was perceived between the volumetric mass transfer coefficient (kLa) and the ozone mass flow rate (19.3-77 g h-1 in 600 mL of the 1 M H2SO4 solution). The rate constant (k) was determined in the presence and absence of nonporous plastic spheres (D = 3 mm). In both cases the rate of Mn(II) conversion increased proportionally with the ozone mass flow rate, although the conversions obtained with non-porous plastic spheres (x = 82%) were always higher than those without non-porous plastic spheres (x = 72%). A pseudo-homogenous mass transfer model adequately approximated the experimental data.

Cruz-Díaz, Martín R.; Arauz-Torres, Yennifer; Caballero, Francisco; Lapidus, Gretchen T.; González, Ignacio

2015-01-01

84

Hydrothermal-assisted synthesis of the Na7V4(P2O7)4(PO4)/C nanorod and its fast sodium intercalation chemistry in aqueous rechargeable sodium batteries  

NASA Astrophysics Data System (ADS)

Both high safety and low cost give aqueous rechargeable sodium-ion batteries (ARSB) the opportunity for application in stationary energy storage, but the low operating potential of the existing cathode materials limits its energy density. Here, we introduce a hydrothermal-assisted strategy to prepare the Na7V4(P2O7)4(PO4)/C nanorod and employ it as a novel high-property cathode material for ARSB. The hierarchical structure is formed by direct in situ carbonization of the surfactants (CTAB and oxalic acid) along with the crystallization of Na7V4(P2O7)4(PO4). The prepared Na7V4(P2O7)4(PO4) with a well-defined 1D nanostructure and uniform particle size is wrapped with a thin carbon layer. For the first time, its sodium intercalation chemistry in an aqueous electrolyte was investigated. Based on the reversible phase transformation and high sodium diffusion coefficient, it is demonstrated to be reliable in an aqueous electrolyte with the rapid ion transport capability. A pair of redox plateaus is observed in the charge and discharge curves at 0.961 and 0.944 V (vs. SCE) respectively with the capacity of 51.2 mA h g-1 at 80 mA g-1. Favored by the open ion channel and 1D morphology, the composite exhibits superior high rate capability and 72% of the capacity remains at 1000 mA g-1. The results not only demonstrate a high-property cathode material for ARSB, but also are helpful for design and synthesis of mixed-polyanion electrode materials with tailored architecture.Both high safety and low cost give aqueous rechargeable sodium-ion batteries (ARSB) the opportunity for application in stationary energy storage, but the low operating potential of the existing cathode materials limits its energy density. Here, we introduce a hydrothermal-assisted strategy to prepare the Na7V4(P2O7)4(PO4)/C nanorod and employ it as a novel high-property cathode material for ARSB. The hierarchical structure is formed by direct in situ carbonization of the surfactants (CTAB and oxalic acid) along with the crystallization of Na7V4(P2O7)4(PO4). The prepared Na7V4(P2O7)4(PO4) with a well-defined 1D nanostructure and uniform particle size is wrapped with a thin carbon layer. For the first time, its sodium intercalation chemistry in an aqueous electrolyte was investigated. Based on the reversible phase transformation and high sodium diffusion coefficient, it is demonstrated to be reliable in an aqueous electrolyte with the rapid ion transport capability. A pair of redox plateaus is observed in the charge and discharge curves at 0.961 and 0.944 V (vs. SCE) respectively with the capacity of 51.2 mA h g-1 at 80 mA g-1. Favored by the open ion channel and 1D morphology, the composite exhibits superior high rate capability and 72% of the capacity remains at 1000 mA g-1. The results not only demonstrate a high-property cathode material for ARSB, but also are helpful for design and synthesis of mixed-polyanion electrode materials with tailored architecture. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr05175k

Deng, Chao; Zhang, Sen; Wu, Yongxin

2014-12-01

85

Hierarchically structured MnO2 nanowires supported on hollow Ni dendrites for high-performance supercapacitors  

NASA Astrophysics Data System (ADS)

We report a hierarchical Ni@MnO2 structure consisting of MnO2 nanowires supported on hollow Ni dendrites for high-performance supercapacitors. The Ni@MnO2 structure, which was prepared via a facile electrodeposition method, is highly porous and appears like a forest of pine trees grown vertically on a substrate. At a MnO2 mass loading of 0.35 mg cm-2, the Ni@MnO2 electrode demonstrated a specific capacitance of 1125 F g-1 that is close to the theoretical value. In addition, a remarkable high-rate performance (766 F g-1 at a discharge current density of 100 A g-1) was achieved. Electrochemical tests in a two-electrode configuration for the Ni@MnO2 structure with a high MnO2 loading of 3.6 mg cm-2 showed a low equivalent series resistance (ESR) of 1 ? and a high specific power of 72 kW kg-1. This superior performance can be attributed to the highly porous and hierarchical structure of Ni@MnO2 that favors rapid diffusion of an electrolyte, highly conductive pathway for electron transport, and efficient material utilization.We report a hierarchical Ni@MnO2 structure consisting of MnO2 nanowires supported on hollow Ni dendrites for high-performance supercapacitors. The Ni@MnO2 structure, which was prepared via a facile electrodeposition method, is highly porous and appears like a forest of pine trees grown vertically on a substrate. At a MnO2 mass loading of 0.35 mg cm-2, the Ni@MnO2 electrode demonstrated a specific capacitance of 1125 F g-1 that is close to the theoretical value. In addition, a remarkable high-rate performance (766 F g-1 at a discharge current density of 100 A g-1) was achieved. Electrochemical tests in a two-electrode configuration for the Ni@MnO2 structure with a high MnO2 loading of 3.6 mg cm-2 showed a low equivalent series resistance (ESR) of 1 ? and a high specific power of 72 kW kg-1. This superior performance can be attributed to the highly porous and hierarchical structure of Ni@MnO2 that favors rapid diffusion of an electrolyte, highly conductive pathway for electron transport, and efficient material utilization. Electronic supplementary information (ESI) available: More TEM and SEM images, digital photo, XPS, and XRD of the samples. See DOI: 10.1039/c3nr00209h

Sun, Zhipeng; Firdoz, Shaik; Ying-Xuan Yap, Esther; Li, Lan; Lu, Xianmao

2013-05-01

86

GROUNDWATER RECHARGE MODELING - AN OVERVIEW  

Microsoft Academic Search

Groundwater recharge must be well understood for the effective utilization of water resources. In this article some of the recent studies in groundwater recharge modeling are detailed and discussed. The topics covered include (1) Recharge modeling in deterministic framework, (2)Recharge modeling in stochastic framework, (3) Recharge modeling using electromagnetic surveys (4) Mountain front recharge (5) Natural recharge estimates for India.

D. Nagesh Kumar

87

Lithium recovery from brine using a ?-MnO2/activated carbon hybrid supercapacitor system.  

PubMed

Lithium is one of the most important elements in various fields including energy storage, medicine manufacturing and the glass industry, and demands for lithium are constantly increasing these days. The lime soda evaporation process using brine lake water is the major extraction method for lithium, but this process is not only inefficient and time-consuming but also causes a few environmental problems. Electrochemical recovery processes of lithium ions have been proposed recently, but the better idea for the silver negative electrodes used in these systems is required to reduce its cost or increase long term stability. Here, we report an electrochemical lithium recovery method based on a ?-MnO2/activated carbon hybrid supercapacitor system. In this system, lithium ions and counter anions are effectively captured at each electrode with low energy consumption in a salt solution containing various cationic species or simulated Salar de Atacama brine lake water in Chile. Furthermore, we designed this system as a flow process for practical applications. By experimental analyses, we confirmed that this system has high selectivity and long-term stability, with its performance being retained even after repetitive captures and releases of lithium ions. PMID:25681679

Kim, Seoni; Lee, Jaehan; Kang, Jin Soo; Jo, Kyusik; Kim, Seonghwan; Sung, Yung-Eun; Yoon, Jeyong

2015-04-01

88

MnO2@KCu7S4 NWs hybrid compositions for high-power all-solid-state supercapacitor  

NASA Astrophysics Data System (ADS)

Here we present a high-power all-solid-state supercapacitor based on a novel structure of MnO2@KCu7S4 NWs. The electrodes exhibit excellent electrochemical performance with large specific capacitance of 533 F g-1 and the maximum power density 2.02 kW kg-1, still hold 85% of the capacitance over 6000 cycles. Besides, we also explored the effect of temperature on the capacitance. When compared with capacitance at different temperatures, the specific capacity at 80 °C demonstrates significantly higher. Moreover, two supercapacitors in series can power 41 light-emitting diodes (LEDs) about 4 min. These results suggest that such MnO2@KCu7S4 hybrid composite is promising for next generation high-performance supercapacitors.

Dai, Shuge; Xi, Yi; Hu, Chenguo; Yue, Xule; Cheng, Lu; Wang, Guo

2015-01-01

89

Surface modification of spinel ?-MnO2 and its lithium adsorption properties from spent lithium ion batteries  

NASA Astrophysics Data System (ADS)

Spinel ?-MnO2 ion-sieves are promising materials because of their high selectivity toward lithium ions, and this can be applied to the recovery of lithium from spent lithium ion batteries. However, manganese dissolution loss during the delithiation of LiMn2O4 causes a decrease in adsorption capacity and poor cycling stability for these ion-sieves. To improve the lithium adsorption properties of ?-MnO2 ion-sieves, surface modification with a CeO2 coating was studied using hydrothermal-heterogeneous nucleation. The structure, morphology and composition of the synthesized materials were determined by XRD, SEM, TEM and EDS. The effect of hydrothermal synthesis conditions and the amount of CeO2 coating on the adsorption performance of ?-MnO2 were also investigated. A 0.5 wt.% CeO2-coated ion-sieve was synthesized by heating at 120 °C for 3 h and it had better adsorption properties than the bare samples. The effect of ultrasonic treatment on the lithium extraction ratio from LiMn2O4 upon acid treatment at various temperatures was studied and the results were compared with conventional mechanical stirring. We found that ultrasonic treatment at lower temperature gave almost the same maximum lithium extraction ratio and was more efficient and economic.

Li, Li; Qu, Wenjie; Liu, Fang; Zhao, Taolin; Zhang, Xiaoxiao; Chen, Renjie; Wu, Feng

2014-10-01

90

Determination of elastic properties of a MnO2 coating by surface acoustic wave velocity dispersion analysis  

NASA Astrophysics Data System (ADS)

MnO2 is a material of interest in the development of high energy-density batteries, specifically as a coating material for internal 3D structures, thus ensuring rapid energy deployment. Its electrochemical properties have been mapped extensively, but there are, to the best of the authors' knowledge, no records of the elastic properties of thin film MnO2. Impulsive stimulated thermal scattering (ISTS), also known as the heterodyne diffraction or transient grating technique, was used to determine the Young's modulus (E) and porosity (?) of a 500 nm thick MnO2 coating on a Si(001) substrate. ISTS is an all optical method that is able to excite and detect surface acoustic waves (SAWs) on opaque samples. From the measured SAW velocity dispersion, the Young's modulus and porosity were determined to be E = 25 ± 1 GPa and ? = 42 ± 1 %, respectively. These values were confirmed by independent techniques and determined by a most-squares analysis of the carefully fitted SAW velocity dispersion. This study demonstrates the ability of the presented technique to determine the elastic parameters of a thin, porous film on an anisotropic substrate.

Sermeus, J.; Sinha, R.; Vanstreels, K.; Vereecken, P. M.; Glorieux, C.

2014-07-01

91

Significance of the Henri-Michaelis-Menten theory in abiotic catalysis: catechol oxidation by ?-MnO 2  

NASA Astrophysics Data System (ADS)

The Henri-Michaelis-Menten theory, for more than eight decades, was only restricted to homogeneous enzymatic catalysis. A mimic of an enzymatic kinetics based on the Henri-Michaelis-Menten concept was experimentally observed in heterogeneous catalysis in the present study with ?-MnO 2 as an abiotic catalyst in the oxidation of catechol (1,2-dihydroxybenzene). Using the derived linear forms of Lineweaver-Burk or Hofstee, the data show that similar to the enzyme tyrosinase, the kinetics of the catechol oxidation catalyzed by ?-MnO 2 can be described by the Henri-Michaelis-Menten equation, V0= VmaxS/( Km+ S), where Vmax is the maximum velocity and Km the concentration of the substrate ( S) corresponding to an initial velocity ( V0) half of Vmax. By analogy to the enzymatic kinetics, the parameters Vmax and Km for an heterogeneous abiotic catalysis were derived for the first time. Further, based on the concentration of the active centers of the mineral oxide, the kinetic constants kcat and kcat/ Km, respectively, representing the turnover frequency and the efficiency of the mineral catalyst, were also determined from the derived general rate equation of Briggs and Haldane. As an abiotic catalyst, ?-MnO 2 has a paramount role in the oxidation of phenolic compounds in soil, sediment and water environments. Therefore, the present observation is of fundamental and practical significance in elucidating the affinity between an abiotic catalyst and a substrate based on the Henri-Michaelis-Menten theory.

Naidja, A.; Huang, P. M.

2002-05-01

92

Graphene oxide electrocatalyst on MnO2 air cathode as an efficient electron pump for enhanced oxygen reduction in alkaline solution.  

PubMed

Graphene oxide (GO) was deposited on the surface of a MnO2 air cathode by thermal evaporation at 50°C from a GO colloidal suspension. Fourier transformed infrared spectroscopy and field emission scanning electron microscopy confirmed the presence of GO on the MnO2 air cathode (GO-MnO2). Voltammetry and chrono-amperometry showed increased currents for the oxygen reduction reaction (ORR) in 6?M KOH solution for GO-MnO2 compared to the MnO2 cathode. The GO-MnO2 was used as an air cathode in an alkaline tin-air cell and produced a maximum power density of 13?mW cm(-2), in contrast to MnO2, which produced a maximum power density of 9.2?mW cm(-2). The electrochemical impedance spectroscopy results suggest that the chemical step for the ORR is the rate determining step, as proposed earlier by different researchers. It is suggested that the presence of GO and electrochemically reduced graphene oxide (ERGO) on the MnO2 surface are responsible for the increased rate of this step, whereby GO and ERGO accelerate the process of electron donation to the MnO2 and to adsorbed oxygen atoms. PMID:25765731

Basirun, Wan Jeffrey; Sookhakian, Mehran; Baradaran, Saeid; Endut, Zulkarnain; Mahmoudian, Mohammad Reza; Ebadi, Mehdi; Yousefi, Ramin; Ghadimi, Hanieh; Ahmed, Sohail

2015-01-01

93

Graphene oxide electrocatalyst on MnO2 air cathode as an efficient electron pump for enhanced oxygen reduction in alkaline solution  

PubMed Central

Graphene oxide (GO) was deposited on the surface of a MnO2 air cathode by thermal evaporation at 50°C from a GO colloidal suspension. Fourier transformed infrared spectroscopy and field emission scanning electron microscopy confirmed the presence of GO on the MnO2 air cathode (GO-MnO2). Voltammetry and chrono-amperometry showed increased currents for the oxygen reduction reaction (ORR) in 6?M KOH solution for GO-MnO2 compared to the MnO2 cathode. The GO-MnO2 was used as an air cathode in an alkaline tin-air cell and produced a maximum power density of 13?mW cm?2, in contrast to MnO2, which produced a maximum power density of 9.2?mW cm?2. The electrochemical impedance spectroscopy results suggest that the chemical step for the ORR is the rate determining step, as proposed earlier by different researchers. It is suggested that the presence of GO and electrochemically reduced graphene oxide (ERGO) on the MnO2 surface are responsible for the increased rate of this step, whereby GO and ERGO accelerate the process of electron donation to the MnO2 and to adsorbed oxygen atoms. PMID:25765731

Basirun, Wan Jeffrey; Sookhakian, Mehran; Baradaran, Saeid; Endut, Zulkarnain; Mahmoudian, Mohammad Reza; Ebadi, Mehdi; Yousefi, Ramin; Ghadimi, Hanieh; Ahmed, Sohail

2015-01-01

94

Graphene oxide electrocatalyst on MnO2 air cathode as an efficient electron pump for enhanced oxygen reduction in alkaline solution  

NASA Astrophysics Data System (ADS)

Graphene oxide (GO) was deposited on the surface of a MnO2 air cathode by thermal evaporation at 50°C from a GO colloidal suspension. Fourier transformed infrared spectroscopy and field emission scanning electron microscopy confirmed the presence of GO on the MnO2 air cathode (GO-MnO2). Voltammetry and chrono-amperometry showed increased currents for the oxygen reduction reaction (ORR) in 6 M KOH solution for GO-MnO2 compared to the MnO2 cathode. The GO-MnO2 was used as an air cathode in an alkaline tin-air cell and produced a maximum power density of 13 mW cm-2, in contrast to MnO2, which produced a maximum power density of 9.2 mW cm-2. The electrochemical impedance spectroscopy results suggest that the chemical step for the ORR is the rate determining step, as proposed earlier by different researchers. It is suggested that the presence of GO and electrochemically reduced graphene oxide (ERGO) on the MnO2 surface are responsible for the increased rate of this step, whereby GO and ERGO accelerate the process of electron donation to the MnO2 and to adsorbed oxygen atoms.

Basirun, Wan Jeffrey; Sookhakian, Mehran; Baradaran, Saeid; Endut, Zulkarnain; Mahmoudian, Mohammad Reza; Ebadi, Mehdi; Yousefi, Ramin; Ghadimi, Hanieh; Ahmed, Sohail

2015-03-01

95

Fe-Species-Loaded Mesoporous MnO2 Superstructural Requirements for Enhanced Catalysis.  

PubMed

In this work, a novel catalyst, Fe-species-loaded mesoporous manganese dioxide (Fe/M-MnO2) urchinlike superstructures, has been fabricated successfully in a two-step technique. First, mesoporous manganese dioxide (M-MnO2) urchinlike superstructures have been synthesized by a facile method on a soft interface between CH2Cl2 and H2O without templates. Then the M-MnO2-immobilized iron oxide catalyst was obtained through wetness impregnation and calcination. Microstructural analysis indicated that the M-MnO2 was composed of urchinlike hollow submicrospheres assembled by nanorod building blocks with rich mesoporosity. The Fe/M-MnO2 retained the hollow submicrospheres, which were covered by hybridized composites with broken and shortened MnO2 nanorods. Energy-dispersive X-ray microanalysis was used to determine the availability of Fe loading processes and the homogeneity of Fe in Fe/M-MnO2. Catalytic performances of the M-MnO2 and Fe/M-MnO2 were evaluated in catalytic wet hydrogen peroxide oxidation of methylene blue (MB), a typical organic pollutant in dyeing wastewater. The catalytic degradation displayed highly efficient discoloration of MB when using the Fe/M-MnO2 catalyst, e.g., ca. 94.8% of MB was decomposed when the reaction was conducted for 120 min. The remarkable stability of this Fe/M-MnO2 catalyst in the reaction medium was confirmed by an iron leaching test and reuse experiments. Mechanism analysis revealed that the hydroxyl free radical was responsible for the removal of MB and catalyzed by M-MnO2 and Fe/M-MnO2. MB was transformed into small organic compounds and then further degraded into CO2 and H2O. The new insights obtained in this study will be beneficial for the practical applications of heterogeneous catalysts in wastewater treatments. PMID:25626157

Huang, Ruting; Liu, Yanyu; Chen, Zhiwen; Pan, Dengyu; Li, Zhen; Wu, Minghong; Shek, Chan-Hung; Wu, C M Lawrence; Lai, Joseph K L

2015-02-25

96

Nanostructured transition metal oxides for aqueous hybrid electrochemical supercapacitors  

NASA Astrophysics Data System (ADS)

In this paper, we wish to present an overview of the research carried out in our laboratories with low-cost transition metal oxides (manganese dioxide, iron oxide and vanadium oxide) as active electrode materials for aqueous electrochemical supercapacitors. More specifically, the paper focuses on the approaches that have been used to increase the capacitance of the metal oxides and the cell voltage of the supercapacitor. It is shown that the cell voltage of an electrochemical supercapacitor can be increased significantly with the use of hybrid systems. The most relevant associations are Fe3O4 or activated carbon as the negative electrode and MnO2 as the positive. The cell voltage of the Fe3O4/MnO2 device is 1.8 V and this value was increased to 2.2 V by using activated carbon instead of Fe3O4. These two systems have shown superior behavior compared to a symmetric MnO2/MnO2 device which only works within a 1 V potential window in aqueous K2SO4. Furthermore, the activated carbon/MnO2 hybrid device exhibits a real power density of 605 W/kg (maximum power density =19.0 kW/kg) with an energy density of 17.3 Wh/kg. These values compete well with those of standard electrochemical double layer capacitors working in organic electrolytes.

Cottineau, T.; Toupin, M.; Delahaye, T.; Brousse, T.; Bélanger, D.

2006-03-01

97

Synthesis of NASICON-type structured NaTi2(PO4)3-graphene nanocomposite as an anode for aqueous rechargeable Na-ion batteries  

NASA Astrophysics Data System (ADS)

A new solvothermal strategy combined with calcination has been developed to synthesize NaTi2(PO4)3-graphene nanocomposites. X-ray diffraction, thermogravimetric analysis, field-emission scanning electron microscopy and transmission electron microscopy were performed to characterize their microstructures and morphologies. It was found that NASICON-type structured NaTi2(PO4)3 nanoparticles with highly crystallinity were homogeneously anchored on the surface of conducting graphene nanosheets, forming a two-dimensional hybrid nanoarchitecture. A possible growth mechanism was also discussed based on time-dependent experiments. When used as anode materials for Na-ion batteries, the nanocomposites exhibited excellent electrochemical performance with high-rate capability and excellent cycling stability in 1 M Na2SO4 aqueous electrolyte. The electrode delivered high specific capacities of 110, 85, 65, 40 mA h g-1 at 2, 5, 10 and 20 C, respectively, and still retained 90% of the initial capacity after 100 cycles at 2 C.A new solvothermal strategy combined with calcination has been developed to synthesize NaTi2(PO4)3-graphene nanocomposites. X-ray diffraction, thermogravimetric analysis, field-emission scanning electron microscopy and transmission electron microscopy were performed to characterize their microstructures and morphologies. It was found that NASICON-type structured NaTi2(PO4)3 nanoparticles with highly crystallinity were homogeneously anchored on the surface of conducting graphene nanosheets, forming a two-dimensional hybrid nanoarchitecture. A possible growth mechanism was also discussed based on time-dependent experiments. When used as anode materials for Na-ion batteries, the nanocomposites exhibited excellent electrochemical performance with high-rate capability and excellent cycling stability in 1 M Na2SO4 aqueous electrolyte. The electrode delivered high specific capacities of 110, 85, 65, 40 mA h g-1 at 2, 5, 10 and 20 C, respectively, and still retained 90% of the initial capacity after 100 cycles at 2 C. Electronic supplementary information (ESI) available: Synthesis of graphite oxide, TG curve of NaTi2(PO4)3-GNS, XRD patterns and morphology of GO, TiO2-GNS, Ti5P4O20-GNS, and NaTi2(PO4)3-GNS. See DOI: 10.1039/c3nr06730k

Pang, Gang; Yuan, Changzhou; Nie, Ping; Ding, Bing; Zhu, Jiajia; Zhang, Xiaogang

2014-05-01

98

Structure-property relationship of bifunctional MnO2 nanostructures: highly efficient, ultra-stable electrochemical water oxidation and oxygen reduction reaction catalysts identified in alkaline media.  

PubMed

Manganese oxides of various structures (?-, ?-, and ?-MnO2 and amorphous) were synthesized by facile methods. The electrocatalytic properties of these materials were systematically investigated for catalyzing both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) in alkaline media. Extensive characterization was correlated with the activity study by investigating the crystal structures (XRD, HRTEM), morphologies (SEM), porosities (BET), surfaces (XPS, O2-TPD/MS), and electrochemical properties (Tafel analysis, Koutechy-Levich plots, and constant-current electrolysis). These combined results show that the electrocatalytic activities are strongly dependent on the crystallographic structures, and follow an order of ?-MnO2 > AMO > ?-MnO2 > ?-MnO2. Both OER studies and ORR studies reveal similar structure-determined activity trends in alkaline media. In the OER studies, ?-MnO2 displays an overpotential of 490 mV compared to 380 mV shown by an Ir/C catalyst in reaching 10 mA cm(-2). Meanwhile, ?-MnO2 also exhibits stability for 3 h when supplying a constant current density of 5 mA cm(-2). This was further improved by adding Ni(2+) dopants (ca. 8 h). The superior OER activity was attributed to several factors, including abundant di-?-oxo bridges existing in ?-MnO2 as the protonation sites, analogous to the OEC in PS-II of the natural water oxidation system; the mixed valencies (AOS = 3.7); and the lowest charge transfer resistances (91.8 ?, ? = 430 mV) as revealed from in situ electrochemical impedance spectroscopy (EIS). In the ORR studies, when reaching 3 mA cm(-2), ?-MnO2 shows 760 mV close to 860 mV for the best ORR catalyst (20% Pt/C). The outstanding ORR activity was due to the strongest O2 adsorption capability of ?-MnO2 suggested by temperature-programmed desorption. As a result, this discovery of the structure-related electrocatalytic activities could provide guidance in the further development of easily prepared, scalable, and low-cost catalysts based on metal oxides and their derivatives. PMID:25058174

Meng, Yongtao; Song, Wenqiao; Huang, Hui; Ren, Zheng; Chen, Sheng-Yu; Suib, Steven L

2014-08-13

99

Degradation of aqueous and soil-sorbed estradiol using a new class of stabilized manganese oxide nanoparticles.  

PubMed

Manganese oxide (MnO2) was reported to be effective for degrading aqueous pharmaceutical chemicals. However, little is known about its potential use for degrading soil-sorbed contaminants. To bridge this knowledge gap, we synthesized, for the first time, a class of stabilized MnO2 nanoparticles using carboxymethyl celluloses (CMC) as a stabilizer, and tested their effectiveness for degrading aqueous and soil-sorbed estradiol. The most desired particles (highest reactivity and soil deliverability) were obtained at a CMC/MnO2 molar ratio of 1.39 × 10(-3), which yielded a mean hydrodynamic size of 39.5 nm and a narrow size distribution (SD = 0.8 nm). While non-stabilized MnO2 particles rapidly aggregated and were not transportable through a soil column, CMC-stabilized nanoparticles remained fully dispersed in water and were soil deliverable. At typical aquatic pH (6-7), CMC-stabilized MnO2 exhibited faster degradation kinetics for oxidation of 17?-estradiol than non-stabilized MnO2. The reactivity advantage becomes more evident when used for treating soil-sorbed estradiol owing to the ability of CMC to complex with metal ions and prevent the reactive sites from binding with inhibitive soil components. A retarded first-order rate model was able to interpret the oxidation kinetics for CMC-stabilized MnO2. When used for degrading soil-sorbed estradiol, several factors may inhibit the oxidation effectiveness, including desorption rate, soil-MnO2 interactions, and soil-released metals and reductants. CMC-stabilized MnO2 nanoparticles hold the potential for facilitating in situ oxidative degradation of various emerging contaminants in soil and groundwater. PMID:25543239

Han, Bing; Zhang, Man; Zhao, Dongye; Feng, Yucheng

2015-03-01

100

Arsenic removal from groundwater by MnO2-modified natural clinoptilolite zeolite: effects of pH and initial feed concentration.  

PubMed

Adsorption of arsenic (As(5+)) on natural and MnO(2)-modified clinoptilolite-Ca zeolite adsorbents was investigated to explore the feasibility of removing arsenic from groundwater using natural zeolite adsorbents. The natural and MnO(2)-modified clinoptilolite-Ca zeolite adsorbents were characterized with nitrogen adsorption at 77K for pore textural properties, scanning electron microscopy with energy dispersive X-ray spectroscopy and X-ray fluorescence for morphology, elemental composition and distribution. Batch adsorption equilibrium experiments were conducted to study the effects of pH and initial feed concentration on arsenic removal efficiency. It was found that the amphoteric properties and arsenic removal efficiency of the natural clinoptilolite-Ca zeolite were significantly improved after modification with MnO(2). The MnO(2)-modified zeolite could effectively remove arsenic from water at a wide pH range, and the arsenic removal efficiency that is basically independent of the pH of feed solutions varies slightly with the initial arsenic concentration in the feed solutions. The removal efficiency obtained on the modified zeolite was doubled as compared to that obtained on the unmodified zeolite. The MnO(2)-modified clinoptilolite-Ca zeolite appears to be a promising adsorbent for removing trace arsenic amounts from water. PMID:21398033

Camacho, Lucy M; Parra, Ramona R; Deng, Shuguang

2011-05-15

101

Self-Assembly of Mesoporous Nanotubes Assembled from Interwoven Ultrathin Birnessite-type MnO2 Nanosheets for Asymmetric Supercapacitors  

PubMed Central

Porous nanotubes comprised of MnO2 nanosheets were fabricated with a one-pot hydrothermal method using polycarbonate membrane as the template. The diameter and thickness of nanotubes can be controlled by choice of the membrane pore size and the chemistry. The porous MnO2 nanotubes were used as a supercapacitor electrode. The specific capacitance in a three-electrode system was 365?F g?1 at a current density of 0.25?A g?1 with capacitance retention of 90.4% after 3000 cycles. An asymmetric supercapacitor with porous MnO2 nanotubes as the positive electrode and activated graphene as the negative electrode yielded an energy density of 22.5?Wh kg?1 and a maximum power density of 146.2?kW kg?1; these values exceeded those reported for other MnO2 nanostructures. The supercapacitor performance was correlated with the hierarchical structure of the porous MnO2 nanotubes. PMID:24464344

Huang, Ming; Zhang, Yuxin; Li, Fei; Zhang, Lili; Ruoff, Rodney S.; Wen, Zhiyu; Liu, Qing

2014-01-01

102

Multicopper Oxidase Involvement in Both Mn(II) and Mn(III) Oxidation during Bacterial Formation of MnO2  

PubMed Central

Global cycling of environmental manganese requires catalysis by bacteria and fungi for MnO2 formation, since abiotic Mn(II) oxidation is slow under ambient conditions. Genetic evidence from several bacteria implicates multicopper oxidases (MCOs) as being required for MnO2 formation. However, MCOs catalyze one-electron oxidations, whereas conversion of Mn(II) to MnO2 is a two-electron process. Trapping experiments with pyrophosphate (PP), a Mn(III) chelator, have demonstrated that Mn(III) is an intermediate in Mn(II) oxidation when mediated by exosporium from the Mn-oxidizing bacterium Bacillus SG-1. The reaction of Mn(II) depends on O2 and is inhibited by azide, consistent with MCO catalysis. We show that the subsequent conversion of Mn(III) to MnO2 also depends on O2 and is inhibited by azide. Thus, both oxidation steps appear to be MCO-mediated, likely by the same enzyme, indicated by genetic evidence to be the MnxG gene product. We propose a model of how the manganese oxidase active site may be organized to couple successive electron transfers to the formation of polynuclear Mn(IV) complexes as precursors to MnO2 formation. PMID:22892957

Soldatova, Alexandra V.; Butterfield, Cristina; Oyerinde, Oyeyemi F.; Tebo, Bradley M.; Spiro, Thomas G.

2013-01-01

103

Recycling Application of Li-MnO2 Batteries as Rechargeable Lithium-Air Batteries.  

PubMed

The ever-increasing consumption of a huge quantity of lithium batteries, for example, Li-MnO2 cells, raises critical concern about their recycling. We demonstrate herein that decayed Li-MnO2 cells can be further utilized as rechargeable lithium-air cells with admitted oxygen. We further investigated the effects of lithiated manganese dioxide on the electrocatalytic properties of oxygen-reduction and oxygen-evolution reactions (ORR/OER). The catalytic activity was found to be correlated with the composition of Lix MnO2 electrodes (0rechargeable lithium-air batteries. PMID:25678148

Hu, Yuxiang; Zhang, Tianran; Cheng, Fangyi; Zhao, Qing; Han, Xiaopeng; Chen, Jun

2015-03-27

104

Effect of P2O5 and MnO2 on crystallization of magnetic glass ceramics  

PubMed Central

This work pointed out the effect of adding P2O5 and/or MnO2 on the crystallization behavior of magnetic glass ceramic in the system Fe2O3·ZnO·CaO·SiO2·B2O3. The differential thermal analysis of the quenched samples revealed decrease in the thermal effects by adding P2O5 and/or MnO2 to the base sample. The X-ray diffraction patterns show the development of nanometric magnetite crystals in a glassy matrix. Heat treatment at 800 °C for 2 h, under reducing atmosphere, caused an increase in the amount of the crystallized magnetite with the appearance of minor hematite and Ca2SiO4. The transmission electron microscope revealed a crystallite size in the range 10–30 nm. Magnetic hysteresis cycles were analyzed with a maximum applied field of 25 kOe at room temperature. The prepared magnetic glass ceramics are expected to be useful for localized treatment of cancer. PMID:25685522

Abdel-Hameed, Salwa A.M.; Marzouk, Mohamed A.; Farag, Mohamed M.

2013-01-01

105

Controlled partial-exfoliation of graphite foil and integration with MnO2 nanosheets for electrochemical capacitors.  

PubMed

Here we demonstrate a controlled two-step partial exfoliation method to synthesize functionalized exfoliated graphite substrates. Ultrathin and functionalized graphene sheets anchoring on the graphite provide a large conductive surface area for loading pseudo-capacitive MnO2 nanosheets. The functionalized exfoliated graphite/MnO2 electrode achieved an excellent areal capacitance of 244 mF cm(-2), corresponding to an estimated MnO2 based gravimetric capacitance of 1061 F g(-1), which is just slightly lower than its theoretical value of 1110 F g(-1). More importantly, the seamless integration of graphene sheets and the graphite substrate minimizes the contact resistance, and substantially improves the rate capability of pseudo-capacitive materials. The electrode retained 44.8% of its capacitance when the charging current density increased 50 times from 0.23 to 11.5 mA cm(-2). This novel functionalized exfoliated graphite substrate serves as a promising supporting material that could address the relatively low electrical conductivity of various pseudo-capacitive materials, and increase the mass loading and rate capability of pseudo-capacitors. PMID:25631619

Song, Yu; Feng, Dong-Yang; Liu, Tian-Yu; Li, Yat; Liu, Xiao-Xia

2015-02-12

106

The design of an Fe-12Mn-O.2Ti alloy steel for low temperature use  

NASA Technical Reports Server (NTRS)

An investigation was made to improve the low temperature mechanical properties of Fe-8 approximately 12% Mn-O 2Ti alloy steels. A two-phase(alpha + gamma) tempering in combination with cold working or hot working was identified as an effective treatment. A potential application as a Ni-free cryogenic steel was shown for this alloy. It was also shown that an Fe-8Mn steel could be grain-refined by a purely thermal treatment because of its dislocated martensitic structure and absence of epsilon phase. A significant reduction of the ductile-brittle transition temperature was obtained in this alloy. The nature and origin of brittle fracture in Fe-Mn alloys were also investigated. Two embrittling regions were found in a cooling curve of an Fe-12Mn-O 2Ti steel which was shown to be responsible for intergranular fracture. Auger electron spectroscopy identified no segregation during solution-annealing treatment. Avoiding the embrittling zones by controlled cooling led to a high cryogenic toughness in a solution-annealed condition.

Hwang, S. K.; Morris, J. W., Jr.

1977-01-01

107

Constraints on the utility of MnO2 cartridge method for the extraction of radionuclides: A case study using 234Th  

USGS Publications Warehouse

[1] Large volume (102-103 L) seawater samples are routinely processed to investigate the partitioning of particle reactive radionuclides and Ra between solution and size-fractionated suspended particulate matter. One of the most frequently used methods to preconcentrate these nuclides from such large volumes involves extraction onto three filter cartridges (a prefilter for particulate species and two MnO2-coated filters for dissolved species) connected in series. This method assumes that the extraction efficiency is uniform for both MnO2-coated cartridges, that no dissolved species are removed by the prefilter, and that any adsorbed radionuclides are not desorbed from the MnO2-coated cartridges during filtration. In this study, we utilized 234Th-spiked coastal seawater and deionized water to address the removal of dissolved Th onto prefilters and MnO2-coated filter cartridges. Experimental results provide the first data that indicate (1) a small fraction of dissolved Th (<6%) can be removed by the prefilter cartridge; (2) a small fraction of dissolved Th (<5%) retained by the MnO2 surface can also be desorbed, which undermines the assumption of uniform extraction efficiency for Th; and (3) the absolute and relative extraction efficiencies can vary widely. These experiments provide insight on the variability of the extraction efficiency of MnO 2-coated filter cartridges by comparing the relative and absolute efficiencies and recommend the use of a constant efficiency on the combined activity from two filter cartridges connected in series for future studies of dissolved 234Th and other radionuclides in natural waters using sequential filtration/extraction methods. ?? 2009 by the American Geophysical Union.

Baskaran, M.; Swarzenski, P.W.; Biddanda, B.A.

2009-01-01

108

Break-up of two-dimensional MnO2 nanosheets promotes ultrasensitive pH-triggered theranostics of cancer.  

PubMed

Chemically exfoliated two-dimensional MnO2 nanosheets are successfully modified with amino-polyethylene glycol as a theranostic platform for ultrasensitive stimuli-responsive theranostics of cancer. The highly dispersed MnO2 nanosheets exhibit a unique break-up in the mildly acidic microenvironment of tumor tissues, which could substantially enhance their in vitro and in vivo performances in T1 -weighted magnetic resonance imaging. Such a pH-triggered breaking-up behavior could further promote the fast release of loaded anticancer drugs for concurrent pH-responsive drug release and circumvent the multidrug resistance of cancer cells. PMID:25156250

Chen, Yu; Ye, Delai; Wu, Meiying; Chen, Hangrong; Zhang, Linlin; Shi, Jianlin; Wang, Lianzhou

2014-11-01

109

Facile synthesis of hierarchical Co3O4@MnO2 core-shell arrays on Ni foam for asymmetric supercapacitors  

NASA Astrophysics Data System (ADS)

Hierarchical Co3O4@MnO2 core-shell arrays on Ni foam have been fabricated by a facile hydrothermal approach and further investigated as the electrode for high-performance supercapacitors. Owing to the high conductivity of the well-defined mesoporous Co3O4 nanowire arrays in combination with the large surface area provided by the ultrathin MnO2 nanosheets, the unique designed Co3O4@MnO2 core-shell arrays on Ni foam have exhibited a high specific capacitance (560 F g-1 at a current density of 0.2 A g-1), good rate capability, and excellent cycling stability (95% capacitance retention after 5000 cycles). An asymmetric supercapacitor with Co3O4@MnO2 core-shell nanostructure as the positive electrode and activated microwave exfoliated graphite oxide activated graphene (MEGO) as the negative electrode yielded an energy density of 17.7 Wh kg-1 and a maximum power density of 158 kW kg-1. The rational design of the unique core-shell array architectures demonstrated in this work provides a new and facile approach to fabricate high-performance electrode for supercapacitors.

Huang, Ming; Zhang, Yuxin; Li, Fei; Zhang, Lili; Wen, Zhiyu; Liu, Qing

2014-04-01

110

PVP-Assisted ZrO2 coating on LiMn2O4 spinel cathode nanoparticles prepared by MnO2 nanowire templates  

E-print Network

PVP-Assisted ZrO2 coating on LiMn2O4 spinel cathode nanoparticles prepared by MnO2 nanowire solution. Upon annealing at 600 °C in air, an amorphous ZrO2 nanoscale coating layer was obtained spinel nanorods. The electrochemical cycling results clearly showed that nanoscale ZrO2 coating

Cho, Jaephil

111

High loading MnO2 nanowires on graphene paper: facile electrochemical synthesis and use as flexible electrode for tracking hydrogen peroxide secretion in live cells.  

PubMed

Recent progress in flexible and lightweight electrochemical sensor systems requires the development of paper-like electrode materials. Here, we report a facile and green synthesis of a new type of MnO2 nanowires-graphene nanohybrid paper by one-step electrochemical method. This strategy demonstrates a collection of unique features including the effective electrochemical reduction of graphene oxide (GO) paper and the high loading of MnO2 nanowires on electrochemical reduced GO (ERGO) paper. When used as flexible electrode for nonenzymatic detection of hydrogen peroxide (H2O2), MnO2-ERGO paper exhibits high electrocatalytic activity toward the redox of H2O2 as well as excellent stability, selectivity and reproducibility. The amperometric responses are linearly proportional to H2O2 concentration in the range 0.1-45.4 mM, with a detection limit of 10 ?M (S/N=3) and detection sensitivity of 59.0 ?A cm(-2) mM(-1). These outstanding sensing performances enable the practical application of MnO2-ERGO paper electrode for the real-time tracking H2O2 secretion by live cells macrophages. Therefore, the proposed graphene-based nanohybrid paper electrode with intrinsic flexibility, tailorable shapes and adjustable properties can contribute to the full realization of high-performance flexible electrode material used in point-of-care testing devices and portable instruments for in-vivo clinical diagnostics and on-site environmental monitoring. PMID:25467459

Dong, Shuang; Xi, Jiangbo; Wu, Yanan; Liu, Hongwei; Fu, Chaoyang; Liu, Hongfang; Xiao, Fei

2015-01-01

112

Effect of synthesis duration on the morphological and structural modification of the sea-urchin nanostructured -MnO2 and study of its  

E-print Network

Electron Microscope (TEM), isotherms of N2 adsorption/desorption and BET-BJH models. The effectEffect of synthesis duration on the morphological and structural modification of the sea-urchin nanostructured -MnO2 and study of its electrochemical reactivity in alkaline medium L. Benhaddada,b,c *, C

Boyer, Edmond

113

Electrochemical investigation of the role of MnO2 nanorod catalysts in water containing and anhydrous electrolytes for Li-O2 battery applications.  

PubMed

The electrochemical behaviour of MnO2 nanorod and Super P carbon based Li-O2 battery cathodes in water-containing sulfolane and anhydrous DMSO electrolytes are shown to be linked to specific discharge product formation. During discharge, large layered spherical agglomerates of LiOH were characteristically formed on the MnO2 cathodes while smaller, toroidal, spherical Li2O2 particles and films were formed on the Super P cathodes. In an anhydrous DMSO based electrolyte the LiOH structures were also found on cathodes discharged in the anhydrous electrolyte, suggesting that MnO2 initiates electrochemical decomposition of the DMSO electrolyte to form LiOH via H2O reactions with Li2O2. The LiOH crystals are uniquely formed on MnO2, and segregated to this phase even in mixed oxide-carbon cathodes. In contrast, no Li2O2 toroids were noted on Super P cathodes discharged in the DMSO based electrolytes. Instead, the morphology varied from smaller sheets (at high discharge current) to much larger agglomerates (at low discharge currents). In mixed carbon-MnO2 nanorod cathodes, the use of PVDF initiates H2O formation that affects discharge products and an overall mechanism governing phase formation at MnO2 in sulfolane and anhydrous DMSO with and without PVDF binder is presented. This work highlights the importance of careful consideration of electrolyte-cathode material-discharge product interactions in the search for more stable Li-O2 systems. PMID:25640321

Geaney, Hugh; O'Dwyer, Colm

2015-02-25

114

Improvement in the etching performance of the acrylonitrile-butadiene-styrene resin by MnO2-H3PO4-H2SO4 colloid.  

PubMed

The present study aimed to evaluate the surface etching of the acrylonitrile-butadiene-styrene (ABS) resin in the MnO2-H3PO4-H2SO4 colloid. To enhance the soluble Mn(IV) ion concentration and improve the etching performance of ABS resin, H3PO4 was added as a complexing agent into the MnO2-H2SO4 etching system. The effects of the H2SO4 concentration and etching time on the surface topography, surface roughness, adhesion strength, and the surface chemistry of the ABS substrates were investigated. The optimal oxidation potentials of MnO2 in the colloids decreased from 1.426 to 1.369 V with the addition of H3PO4. Though the etching conditions changed from 70 °C for 20 min to 60 °C for 10 min, the adhesion strength between the ABS substrates and electroless copper film increased from 1.19 to 1.33 KN/m after etching treatment. This could be attributed to the significant increase of the soluble Mn(IV) ion concentration in the MnO2-H3PO4-H2SO4 colloid. The surface chemistry results demonstrated that the oxidation reaction of -C?C- bonds in the polybutadiene phase was accelerated in the etching process by the addition of H3PO4, and the abundant -COOH and -OH groups were formed rapidly on the ABS surface with the etching treatment. These results were in agreement with the results of surface scanning electron microscopic observations and adhesion strength measurement. The results suggested that the MnO2-H3PO4-H2SO4 colloid was an effective surface etching system for the ABS surface roughness. PMID:23611532

Zhao, Wenxia; Ding, Jie; Wang, Zenglin

2013-05-21

115

Rechargeability and economic aspects of alkaline zinc-manganese dioxide cells for electrical storage and load leveling  

NASA Astrophysics Data System (ADS)

Batteries based on manganese dioxide (MnO2) cathodes are good candidates for grid-scale electrical energy storage, as MnO2 is low-cost, relatively energy dense, safe, water-compatible, and non-toxic. Alkaline Zn-MnO2 cells, if cycled at reduced depth of discharge (DOD), have been found to achieve substantial cycle life with battery costs projected to be in the range of 100 to 150 per kWh (delivered). Commercialization of rechargeable Zn-MnO2 batteries has in the past been hampered due to poor cycle life. In view of this, the work reported here focuses on the long-term rechargeability of prismatic MnO2 cathodes at reduced DOD when exposed to the effects of Zn anodes and with no additives or specialty materials. Over 3000 cycles is shown to be obtainable at 10% DOD with energy efficiency >80%. The causes of capacity fade during long-term cycling are also investigated and appear to be mainly due to the formation of irreversible manganese oxides in the cathode. Analysis of the data indicates that capacity loss is rapid in the first 250 cycles, followed by a regime of stability that can last for thousands of cycles. A model has been developed that captures the behavior of the cells investigated using measured state of charge (SOC) data as input. An approximate economic analysis is also presented to evaluate the economic viability of Zn-MnO2 batteries based on the experiments reported here.

Ingale, Nilesh D.; Gallaway, Joshua W.; Nyce, Michael; Couzis, Alexander; Banerjee, Sanjoy

2015-02-01

116

Estimating groundwater recharge  

USGS Publications Warehouse

Groundwater recharge is the entry of fresh water into the saturated portion of the subsurface part of the hydrologic cycle, the modifier "saturated" indicating that the pressure of the pore water is greater than atmospheric.

Stonestrom, David A.

2011-01-01

117

Artificial recharge of groundwater  

NASA Astrophysics Data System (ADS)

The Task Committee on Guidelines for Artificial Recharge of Groundwater, of the American Society of Civil Engineers' (ASCE) Irrigation and Drainage Division, sponsored an International Symposium on Artificial Recharge of Groundwater at the Inn-at-the-Park Hotel in Anaheim, Calif., August 23-27, 1988. Cosponsors were the U.S. Geological Survey, California Department of Water Resources, University of California Water Resources Center, Metropolitan Water District of Southern California, with cooperation from the U.S. Bureau of Reclamation, International Association of Hydrological Sciences, American Water Resources Association, U.S. Agency for International Development, World Bank, United Nations Department of Technical Cooperation for Development, and a number of local and state organizations.Because of the worldwide interest in artificial recharge and the need to develop efficient recharge facilities, the Anaheim symposium brought together an interdisciplinary group of engineers and scientists to provide a forum for many professional disciplines to exchange experiences and findings related to various types of artificial recharge; learn from both successful and unsuccessful case histories; promote technology transfer between the various disciplines; provide an education resource for communication with those who are not water scientists, such as planners, lawyers, regulators, and the public in general; and indicate directions by which cities or other entities can save funds by having reasonable technical guidelines for implementation of a recharge project.

118

The effect of Na0.44MnO2 formation in Na+-modified spinel LiMn2O4  

NASA Astrophysics Data System (ADS)

Na0.44MnO2 impure phase is formed during the synthetic process of Na+-modified spinel LiMn2O4 by solid state reaction which is confirmed by x-ray diffraction analysis. Scanning electron microscopy, transmission electron microscopy and galvanostatic charge-discharge measurements are carried out to investigate the effect of the formation of Na0.44MnO2 impurity on the morphology and electrochemical properties of the spinel material. The results show that the spinel material with impure phase exhibits improved cyclability compared to that of the pristine LiMn2O4. The improved electrochemical performance is mainly ascribed to the improved crystallinity of the spinel particles, enhanced stability of the spinel structure and good electronic conductivity of the composite.

Xiong, Lilong; Xu, Youlong; Wu, Weiguo; Lei, Pei; Tao, Tao; Dong, Xin

2014-07-01

119

Effects of MnO 2 on the electromagnetic properties of NiCuZn ferrites prepared by sol-gel auto-combustion  

NASA Astrophysics Data System (ADS)

Mn-doped NiCuZn ferrites with compositions of (Ni 0.2Cu 0.2Zn 0.6)O(Fe 2- x,Mn xO 3) 0.98 ( x=0, 0.02, 0.04, 0.06) were prepared by a novel sol-gel auto-combustion process. The synthesized nano-sized ferrite powders can be sintered at 900°C, and the sintered ferrites are characterized by fine-grained microstructural feature and high permeability. Mn content in formulations largely affects the grain size and main electromagnetic properties of sintered NiCuZn ferrites. With increasing Mn content, the initial permeability is significantly increased, while the electrical resistivity and quality factor are decreased. The dielectric constant and dissipation factor are also affected by the incorporation of MnO 2. The possible mechanism for the influence of MnO 2 on the electromagnetic properties was discussed.

Yue, Zhenxing; Zhou, Ji; Li, Longtu; Gui, Zhilun

2001-08-01

120

Low-temperature molar heat capacities and entropies of MnO2 (pyrolusite), Mn3O4 (hausmanite), and Mn2O3 (bixbyite)  

USGS Publications Warehouse

Pyrolusite (MnO2), hausmanite (Mn3O4), and bixbyite (Mn2O3), are important ore minerals of manganese and accurate values for their thermodynamic properties are desirable to understand better the {p(O2), T} conditions of their formation. To provide accurate values for the entropies of these important manganese minerals, we have measured their heat capacities between approximately 5 and 380 K using a fully automatic adiabatically-shielded calorimeter. All three minerals are paramagnetic above 100 K and become antiferromagnetic or ferrimagnetic at lower temperatures. This transition is expressed by a sharp ??-type anomaly in Cpmo for each compound with Ne??el temperatures TN of (92.2??0.2), (43.1??0.2), and (79.45??0.05) K for MnO2, Mn3O4, and Mn2O3, respectively. In addition, at T ??? 308 K, Mn2O3 undergoes a crystallographic transition, from orthorhombic (at low temperatures) to cubic. A significant thermal effect is associated with this change. Hausmanite is ferrimagnetic below TN and in addition to the normal ??-shape of the heat-capacity maxima in MnO2 and Mn2O3, it has a second rounded maximum at 40.5 K. The origin of this subsidiary bump in the heat capacity is unknown but may be related to a similar "anomalous bump" in the curve of magnetization against temperature at about 39 K observed by Dwight and Menyuk.(1) At 298.15 K the standard molar entropies of MnO2, Mn3O4, and Mn2O3, are (52.75??0.07), (164.1??0.2), and (113.7??0.2) J??K-1??mol-1, respectively. Our value for Mn3O4 is greater than that adopted in the National Bureau of Standards tables(2) by 14 per cent. ?? 1985.

Robie, R.A.; Hemingway, B.S.

1985-01-01

121

Synthesis and characterization of one-dimensional K0.27MnO2·0.5H2O  

Microsoft Academic Search

Potassium manganese oxide (K0.27MnO2·0.5H2O) nanowires\\/ribbons have been synthesized successfully by a simple hydrothermal method at low temperature. The nanoribbons have rectangular sections with widths of 50 200 nm, thicknesses of 20 25 nm, and lengths up to hundreds of micrometers; nanowires have diameters of 20 30 nm and lengths up to hundreds of micrometers. A plausible formation mechanism of the

H. T. Zhang; X. H. Chen; J. H. Zhang; G. Y. Wang; S. Y. Zhang; Y. Z. Long; Z. J. Chen; N. L. Wang

2005-01-01

122

All-solid-state electrochemical capacitors using MnO2 electrode/SiO2-Nafion electrolyte composite prepared by the sol-gel process  

NASA Astrophysics Data System (ADS)

Electrode-electrolyte composites of MnO2 active material, acetylene black (AB), and SiO2-Nafion solid electrolyte were prepared using the sol-gel process to form good solid-solid interfaces. The composites were obtained by the addition of MnO2 and AB into a sol of hydrolyzed tetraethoxysilane with Nafion, and successive solidification of the precursor sol. Scanning electron microscope and energy dispersive X-ray spectroscopy measurements show that good solid-solid interface is formed between electrodes and solid electrolytes in the composites. All-solid-state hybrid capacitors were fabricated using the composites or the hand-grinding mixture of MnO2, AB and SiO2-Nafion powder as positive electrodes, activated carbon powder as a negative electrode, and phosphosilicate gel as a solid electrolyte. The all-solid-state hybrid capacitors using the composites exhibit larger capacitances and better rate performance than the capacitors using the electrode prepared by hand-mixing of powders. Specific discharge capacitances of the capacitor with the composite are 85 F g-1 for the one with the composite electrode and 48 F g-1 for the one with the hand-mixed electrode, at 1 mA cm-2. Moreover, the all-solid-state capacitors using the composite electrode can be operated at temperatures between -30 °C and 60 °C.

Shimamoto, Kazushi; Tadanaga, Kiyoharu; Tatsumisago, Masahiro

2014-02-01

123

The Exxon rechargeable cells  

NASA Astrophysics Data System (ADS)

The design and performance of ambient temperature secondary cells based on the titanium disulfide cathode are discussed. These limited performance products were developed for microelectronic applications such as solar rechargeable watches and clocks which require low drain rate and do not require many deep cycles.

Malachesky, P. A.

1980-04-01

124

WASHINGTON UNIVERSITY RECHARGE CENTERS  

E-print Network

). The government monitors, by routine audits, the University's compliance with federal regulations regarding of federal grants and contracts, we must comply with applicable government requirements (i.e., A-21, A-133 purchases should not be included in billing rates. Recharge centers with less than $250,000 in annual

Subramanian, Venkat

125

Rechargeability of alkaline Zn-MnO2 batteries: Experimental and mathematical studies  

NASA Astrophysics Data System (ADS)

Batteries based on manganese dioxide (MnO2) cathodes are good candidates for grid-scale electrical energy storage, as MnO2 is low-cost, relatively energy dense, safe, water-compatible, and non-toxic. Alkaline Zn-MnO2 cells, if cycled at reduced depth of discharge (DOD), have been found to achieve substantial cycle life with battery costs projected to be in the range of $100 to 150/kWh (delivered). Commercialization of rechargeable Zn-MnO2 batteries has in the past been hampered due to poor cycle life. In view of this, the work reported here focuses on the long-term rechargeability of prismatic MnO2 cathodes at reduced DOD when exposed to the effects of Zn anodes and with no additives or specialty materials. Over 3000 cycles is shown to be obtainable at 10% DOD with energy efficiency >80%. The causes of capacity fade during long-term cycling are also investigated and appear to be mainly due to the formation of irreversible manganese oxides in the cathode. Analysis of the data indicates that capacity loss is rapid in the first 250 cycles, followed by a regime of stability that can last for thousands of cycles. A model has been developed that captures the behavior of the cells investigated using measured state of charge (SOC) data as input. An approximate economic analysis is also presented to evaluate the economic viability of Zn-MnO2 batteries based on the experiments reported here. The potential of Zn-MnO2 batteries as starting-lighting-ignition (SLI) batteries was also investigated. The impedance contributing parameters at high discharge rates were identified and their effect at high currents was investigated. It was found that prismatic configuration; optimized electrode thickness, electrolyte concentration and electrode size help to achieve high currents for short period of time. In this work, the potential of Zn-MnO 2 batteries for energy as well as power supply has been successfully investigated.

Ingale, Nilesh D.

126

The ozonation of pyruvic acid in aqueous solutions catalyzed by suspended and dissolved manganese  

Microsoft Academic Search

Reaction mechanisms and kinetics of manganese-catalyzed ozonation of pyruvic acid in aqueous solution are investigated. Experiments performed in the pH range 2.0–4.0 show that the reactivity is strongly enhanced by heterogeneous and homogeneous catalytic mechanisms, which are activated by suspended MnO2 particles and by dissolved Mn ions, respectively. Homogeneous mechanisms and related kinetics are elucidated.

R. Andreozzi; V. Caprio; A. Insola; R. Marotta; V. Tufano

1998-01-01

127

Rechargeable Magnesium Power Cells  

NASA Technical Reports Server (NTRS)

Rechargeable power cells based on magnesium anodes developed as safer alternatives to high-energy-density cells like those based on lithium and sodium anodes. At cost of some reduction in energy density, magnesium-based cells safer because less susceptible to catastrophic meltdown followed by flames and venting of toxic fumes. Other advantages include ease of handling, machining, and disposal, and relatively low cost.

Koch, Victor R.; Nanjundiah, Chenniah; Orsini, Michael

1995-01-01

128

Microstructure and current-voltage characteristics of praseodymium-doped zinc oxide varistors containing MnO 2 , Sb 2 O 3 and Co 3 O 4  

Microsoft Academic Search

The effects of the oxide additives MnO2, Sb2O3 and Co3O4 commonly incorporated in commercial Bi2O3-doped ZnO varistors on the microstructure and the current-voltage characteristics of 0.5 mol% Pr6O11-doped ZnO varistors have been studied. A 1 mol% addition of Co3O4 to the ZnO-Pr6O11 binary system does not produce any additional secondary phases in addition to Pr oxides. In contrast to this,

H. H. Hng; K. M. Knowles

2002-01-01

129

MnO2 Nanosheets Grown on Nitrogen-Doped Hollow Carbon Shells as a High-Performance Electrode for Asymmetric Supercapacitors.  

PubMed

A hierarchical hollow hybrid composite, namely, MnO2 nanosheets grown on nitrogen-doped hollow carbon shells (NHCSs@MnO2 ), was synthesized by a facile in situ growth process followed by calcination. The composite has a high surface area (251?m(2) g(-1) ) and mesopores (4.5?nm in diameter), which can efficiently facilitate transport during electrochemical cycling. Owing to the synergistic effect of NHCSs and MnO2 , the composite shows a high specific capacitance of 306?F?g(-1) , good rate capability, and an excellent cycling stability of 95.2?% after 5000 cycles at a high current density of 8?A?g(-1) . More importantly, an asymmetric supercapacitor (ASC) assembled by using NHCSs@MnO2 and activated carbon as the positive and negative electrodes exhibits high specific capacitance (105.5?F?g(-1) at 0.5?A?g(-1) and 78.5?F?g(-1) at 10?A?g(-1) ) with excellent rate capability, achieves a maximum energy density of 43.9?Wh?kg(-1) at a power density of 408?W?kg(-1) , and has high stability, whereby the ASC retains 81.4?% of its initial capacitance at a current density of 5?A?g(-1) after 4000 cycles. Therefore, the NHCSs@MnO2 electrode material is a promising candidate for future energy-storage systems. PMID:25801647

Li, Lei; Li, Rumin; Gai, Shili; Ding, Shujiang; He, Fei; Zhang, Milin; Yang, Piaoping

2015-05-01

130

Evolution of strategies for modern rechargeable batteries.  

PubMed

This Account provides perspective on the evolution of the rechargeable battery and summarizes innovations in the development of these devices. Initially, I describe the components of a conventional rechargeable battery along with the engineering parameters that define the figures of merit for a single cell. In 1967, researchers discovered fast Na(+) conduction at 300 K in Na ?,?''-alumina. Since then battery technology has evolved from a strongly acidic or alkaline aqueous electrolyte with protons as the working ion to an organic liquid-carbonate electrolyte with Li(+) as the working ion in a Li-ion battery. The invention of the sodium-sulfur and Zebra batteries stimulated consideration of framework structures as crystalline hosts for mobile guest alkali ions, and the jump in oil prices in the early 1970s prompted researchers to consider alternative room-temperature batteries with aprotic liquid electrolytes. With the existence of Li primary cells and ongoing research on the chemistry of reversible Li intercalation into layered chalcogenides, industry invested in the production of a Li/TiS2 rechargeable cell. However, on repeated recharge, dendrites grew across the electrolyte from the anode to the cathode, leading to dangerous short-circuits in the cell in the presence of the flammable organic liquid electrolyte. Because lowering the voltage of the anode would prevent cells with layered-chalcogenide cathodes from competing with cells that had an aqueous electrolyte, researchers quickly abandoned this effort. However, once it was realized that an oxide cathode could offer a larger voltage versus lithium, researchers considered the extraction of Li from the layered LiMO2 oxides with M = Co or Ni. These oxide cathodes were fabricated in a discharged state, and battery manufacturers could not conceive of assembling a cell with a discharged cathode. Meanwhile, exploration of Li intercalation into graphite showed that reversible Li insertion into carbon occurred without dendrite formation. The SONY corporation used the LiCoO2/carbon battery to power their initial cellular telephone and launched the wireless revolution. As researchers developed 3D transition-metal hosts, manufacturers introduced spinel and olivine hosts in the Lix[Mn2]O4 and LiFe(PO4) cathodes. However, current Li-ion batteries fall short of the desired specifications for electric-powered automobiles and the storage of electrical energy generated by wind and solar power. These demands are stimulating new strategies for electrochemical cells that can safely and affordably meet those challenges. PMID:22746097

Goodenough, John B

2013-05-21

131

Effects of vanadium and manganese concentrations on the composition, structure and electrical properties of ZnO-rich MnO 2–V 2O 5–ZnO varistors  

Microsoft Academic Search

The composition, structure and electrical properties of ZnO-rich MnO2–V2O5–ZnO varistors have been analysed. Samples were prepared by a conventional powder route with 0.25–0.75 V2O5 mol% and 0.1–1.5 MnO2 mol% concentrations. All the microstructures consisted of ZnO grains with zinc vanadates as minority secondary phases. The quantity and type of zinc vanadates found depended on the cooling rate. ?-Zn3(VO4)2 and Zn4V2O9

Heriberto Pfeiffer; Kevin M. Knowles

2004-01-01

132

FLUIDIC: Metal Air Recharged  

ScienceCinema

Fluidic, with the help of ARPA-E funding, has developed and deployed the world's first proven high cycle life metal air battery. Metal air technology, often used in smaller scale devices like hearing aids, has the lowest cost per electron of any rechargeable battery storage in existence. Deploying these batteries for grid reliability is competitive with pumped hydro installations while having the advantages of a small footprint. Fluidic's battery technology allows utilities and other end users to store intermittent energy generated from solar and wind, as well as maintain reliable electrical delivery during power outages. The batteries are manufactured in the US and currently deployed to customers in emerging markets for cell tower reliability. As they continue to add customers, they've gained experience and real world data that will soon be leveraged for US grid reliability.

Friesen, Cody

2014-04-02

133

FLUIDIC: Metal Air Recharged  

SciTech Connect

Fluidic, with the help of ARPA-E funding, has developed and deployed the world's first proven high cycle life metal air battery. Metal air technology, often used in smaller scale devices like hearing aids, has the lowest cost per electron of any rechargeable battery storage in existence. Deploying these batteries for grid reliability is competitive with pumped hydro installations while having the advantages of a small footprint. Fluidic's battery technology allows utilities and other end users to store intermittent energy generated from solar and wind, as well as maintain reliable electrical delivery during power outages. The batteries are manufactured in the US and currently deployed to customers in emerging markets for cell tower reliability. As they continue to add customers, they've gained experience and real world data that will soon be leveraged for US grid reliability.

Friesen, Cody

2014-03-07

134

Rechargeable battery legislative and regulatory issues  

Microsoft Academic Search

Rechargeable batteries and rechargeable consumer products are regulated under a complex system of state, federal and international laws. These laws are designed to promote safety and the environmentally sound recycling or proper disposal of rechargeable batteries and battery-powered products. These laws affect virtually every person involved with rechargeable products, including manufacturers, distributors, retailers, consumers, recyclers, transporters and waste management authorities.

N. England

1993-01-01

135

Chemical bath deposition synthesis and electrochemical properties of MnO2 thin film: Effect of deposition time and bath temperature  

NASA Astrophysics Data System (ADS)

Manganese dioxide (MnO2) films with different nanostructures were deposited on indium tin oxide (ITO) glasses by using chemical bath deposition (CBD). Deposition temperature and time were varied from 60 °C to 90 °C and from 2 h to 72 h, respectively. The samples have been characterized using an X-ray diffraction (XRD), field emission scanning electron microscope (SEM) and an electrochemical workstation. The films deposited at 60 °C for 8 h showed that obtained nanoflowers had an amorphous nature, while those deposited at higher temperatures of 70, 80 and 90 °C showed a well-developed nanowire and nanorod morphology. However, those which were deposited at 60 °C, showed the best electrochemical properties, including a higher specific capacitance, good rate of performance and a cycling stability (93 % loss of the initial value after 10,000 cycles).

Aref, A. A.; Tang, Y. W.

2014-12-01

136

Chemically rechargeable battery  

NASA Technical Reports Server (NTRS)

Batteries (50) containing oxidized, discharged metal electrodes such as an iron-air battery are charged by removing and storing electrolyte in a reservoir (98), pumping fluid reductant such as formalin (aqueous formaldehyde) from a storage tank (106) into the battery in contact with the surfaces of the electrodes. After sufficient iron hydroxide has been reduced to iron, the spent reductant is drained, the electrodes rinsed with water from rinse tank (102) and then the electrolyte in the reservoir (106) is returned to the battery. The battery can be slowly electrically charged when in overnight storage but can be quickly charged in about 10 minutes by the chemical procedure of the invention.

Graf, James E. (Inventor); Rowlette, John J. (Inventor)

1984-01-01

137

Novel electrolyte chemistries for Mg-Ni rechargeable batteries.  

SciTech Connect

Commercial hybrid electric vehicles (HEV) and battery electric vehicles (BEV) serve as means to reduce the nation's dependence on oil. Current electric vehicles use relatively heavy nickel metal hydride (Ni-MH) rechargeable batteries. Li-ion rechargeable batteries have been developed extensively as the replacement; however, the high cost and safety concerns are still issues to be resolved before large-scale production. In this study, we propose a new highly conductive solid polymer electrolyte for Mg-Ni high electrochemical capacity batteries. The traditional corrosive alkaline aqueous electrolyte (KOH) is replaced with a dry polymer with conductivity on the order of 10{sup -2} S/cm, as measured by impedance spectroscopy. Several potential novel polymer and polymer composite candidates are presented with the best-performing electrolyte results for full cell testing and cycling.

Garcia-Diaz, Brenda (Savannah River National Laboratory); Kane, Marie; Au, Ming (Savannah River National Laboratory)

2010-10-01

138

The simplest ENSO recharge oscillator Gerrit Burgers  

E-print Network

The simplest ENSO recharge oscillator Gerrit Burgers Royal Netherlands Meteorological Institute: Burgers, G., F.-F. Jin, and G. J. van Oldenborgh (2005), The simplest ENSO recharge oscillator, Geophys

Wang, Yuqing

139

Identifying Recharge Location Using Noble Gas Recharge Temperatures, Pajarito Plateau, New Mexico  

Microsoft Academic Search

The solubility of noble gases in water is temperature dependent. Noble gas concentrations in ground water can therefore be used to determine the temperature at the water table at the recharge location (recharge temperature). The Pajarito Plateau in Northern New Mexico is an example of a hydrogeologic setting where noble gas recharge temperatures provide valuable information about recharge location which

A. H. Manning; M. Dale

2008-01-01

140

Choosing appropriate techniques for quantifying groundwater recharge  

USGS Publications Warehouse

Various techniques are available to quantify recharge; however, choosing appropriate techniques is often difficult. Important considerations in choosing a technique include space/time scales, range, and reliability of recharge estimates based on different techniques; other factors may limit the application of particular techniques. The goal of the recharge study is important because it may dictate the required space/time scales of the recharge estimates. Typical study goals include water-resource evaluation, which requires information on recharge over large spatial scales and on decadal time scales; and evaluation of aquifer vulnerability to contamination, which requires detailed information on spatial variability and preferential flow. The range of recharge rates that can be estimated using different approaches should be matched to expected recharge rates at a site. The reliability of recharge estimates using different techniques is variable. Techniques based on surface-water and unsaturated-zone data provide estimates of potential recharge, whereas those based on groundwater data generally provide estimates of actual recharge. Uncertainties in each approach to estimating recharge underscore the need for application of multiple techniques to increase reliability of recharge estimates.

Scanlon, B.R.; Healy, R.W.; Cook, P.G.

2002-01-01

141

Management plans for artificial reservoir recharge  

Microsoft Academic Search

Reservoir recharge is one of the artifical recharge methods that is used extensively to replenish groundwater, especially in arid regions. The efficiency of this method is greatly reduced if an appropriate management plan is not implemented. Selection of a management plan requires precursory site evaluations, surveys and careful consideration of the constraints affecting recharge water and the aquifer. This article

Uygur Sendil

1990-01-01

142

Manganese oxide cathodes for rechargeable batteries  

Microsoft Academic Search

Manganese oxides are considered as promising cathodes for rechargeable batteries due to their low cost and low toxicity as well as the abundant natural resources. In this dissertation, manganese oxides have been investigated as cathodes for both rechargeable lithium and alkaline batteries. Nanostructured lithium manganese oxides designed for rechargeable lithium cells have been synthesized by reducing lithium permanganate with methanol

Dongmin Im

2002-01-01

143

Sandwich-structured nanohybrid paper based on controllable growth of nanostructured MnO2 on ionic liquid functionalized graphene paper as a flexible supercapacitor electrode.  

PubMed

A sandwich-structured flexible supercapacitor electrode has been developed based on MnO2 nanonest (MNN) modified ionic liquid (IL) functionalized graphene paper (GP), which is fabricated by functionalizing graphene nanosheets with an amine-terminated IL (i.e., 1-(3-aminopropyl)-3-methylimidazolium bromide) to form freestanding IL functionalized GP (IL-GP), and then modifying IL-GP with a unique MNN structure via controllable template-free ultrasonic electrodeposition. The as-obtained MNN modified IL-GP (MNN/IL-GP) inherits the excellent pseudocapacity of the metal oxide, the high conductivity and electric double layer charging/discharging of IL-graphene composites, and therefore shows an enhanced supercapacitor performance. The maximum specific capacitance of 411 F g(-1) can be achieved by chronopotentiometry at a current density of 1 A g(-1). Meanwhile, the MNN/IL-GP electrode exhibits excellent rate capability and cycling stability, its specific capacitance is maintained at 70% as the current densities increase from 1 to 20 A g(-1) and 85% at a current density of 10 A g(-1) after 10?000 cycles. More importantly, the MNN/IL-GP displays distinguished mechanical stability and flexibility for device packaging, although its thickness is merely 8 ?m. These features collectively demonstrate the potential of MNN/IL-GP as a high-performance paper electrode for flexible and lightweight and highly efficient electrochemical capacitor applications. PMID:25848920

Sun, Yimin; Fang, Zheng; Wang, Chenxu; Ariyawansha, K R Rakhitha Malinga; Zhou, Aijun; Duan, Hongwei

2015-04-24

144

Domain size engineering in 0.5%MnO2-(K0.5Na0.5)NbO3 lead free piezoelectric crystals  

NASA Astrophysics Data System (ADS)

The piezoelectric property of [001]-oriented 0.5%MnO2-(K0.5Na0.5)NbO3 (Mn-KNN) crystals was studied as a function of domain size, being poled with different electric fields at 205 °C (above orthorhombic to tetragonal phase transition temperature To-t). The piezoelectric coefficients d33 and relative dielectric constants ?r were found to increase from 270 pC/N to 350 pC/N and 730 to 850 with the domain size decreasing from 9 to 2 ?m, respectively. The thermal stability of piezoelectric property was investigated, where the d33 value for [001]-oriented Mn-KNN crystals with domain size of 2 ?m was found to decrease to 330 pC/N at depoling temperature of 150 °C, with minimal variation of ˜6%. The results reveal that domain size engineering is an effective way to improve the piezoelectric properties of Mn-KNN crystals.

Lin, Dabin; Zhang, Shujun; Cai, Changlong; Liu, Weiguo

2015-02-01

145

A possible evolutionary origin for the Mn4 cluster of the photosynthetic water oxidation complex from natural MnO2 precipitates in the early ocean.  

PubMed

The photosynthetic water oxidation complex consists of a cluster of four Mn atoms bridged by O atoms, associated with Ca2+ and Cl-, and incorporated into protein. The structure is similar in higher plants and algae, as well as in cyanobacteria of more ancient lineage, dating back more than 2.5 billion years ago on Earth. It has been proposed that the proto-enzyme derived from a component of a natural early marine manganese precipitate that contained a CaMn4O9 cluster. A variety of MnO2 minerals are found in nature. Three major classes are spinels, sheet-like layered structures, and three-dimensional networks that contain parallel tunnels. These relatively open structures readily incorporate cations (Na+, Li+, Mg2+, Ca2+, Ba2+, H+, and even Mn2+) and water. The minerals have different ratios of Mn(III) and Mn(IV) octahedrally coordinated to oxygens. Using x-ray spectroscopy we compare the chemical structures of Mn in the minerals with what is known about the arrangement in the water oxidation complex to define the parameters of a structural model for the photosynthetic catalytic site. This comparison provides for the structural model a set of candidate Mn(4) clusters-some previously proposed and considered and others entirely novel. PMID:12077302

Sauer, Kenneth; Yachandra, Vittal K

2002-06-25

146

A possible evolutionary origin for the Mn4 cluster of the photosynthetic water oxidation complex from natural MnO2 precipitates in the early ocean  

PubMed Central

The photosynthetic water oxidation complex consists of a cluster of four Mn atoms bridged by O atoms, associated with Ca2+ and Cl?, and incorporated into protein. The structure is similar in higher plants and algae, as well as in cyanobacteria of more ancient lineage, dating back more than 2.5 billion years ago on Earth. It has been proposed that the proto-enzyme derived from a component of a natural early marine manganese precipitate that contained a CaMn4O9 cluster. A variety of MnO2 minerals are found in nature. Three major classes are spinels, sheet-like layered structures, and three-dimensional networks that contain parallel tunnels. These relatively open structures readily incorporate cations (Na+, Li+, Mg2+, Ca2+, Ba2+, H+, and even Mn2+) and water. The minerals have different ratios of Mn(III) and Mn(IV) octahedrally coordinated to oxygens. Using x-ray spectroscopy we compare the chemical structures of Mn in the minerals with what is known about the arrangement in the water oxidation complex to define the parameters of a structural model for the photosynthetic catalytic site. This comparison provides for the structural model a set of candidate Mn4 clusters—some previously proposed and considered and others entirely novel. PMID:12077302

Sauer, Kenneth; Yachandra, Vittal K.

2002-01-01

147

A possible evolutionary origin for the Mn4 cluster of the photosynthetic water oxidation complex from natural MnO2 precipitates in the early ocean  

SciTech Connect

The photosynthetic water oxidation complex consists of a cluster of 4 Mn atoms bridged by O atoms, associated with Ca2+ and Cl- and incorporated into protein. The structure is similar in higher plants and algae, as well as in cyanobacteria of more ancient lineage, dating back more than 2.5 Ga on Earth. It has been proposed that the proto-enzyme derived from a component of a natural early marine manganese precipitate that contained a CaMn4O9 cluster. A variety of MnO2 minerals is found in nature. Three major classes are spinels, sheet-like layered structures and 3-dimensional networks that contain parallel tunnels. These relatively open structures readily incorporate cations (Na+, Li+, Mg2+, Ca2+, Ba2+, H+ and even Mn2+) and water. The minerals have different ratios of Mn(III) and Mn(IV) octahedrally coordinated to oxygens. Using X-ray spectroscopy we compare the chemical structures of Mn in the minerals with what is known about the arrangement in the water-oxidation complex to define the parameters of a structural model for the photosynthetic catalytic site. This comparison provides for the structural model a set of candidate Mn4 clusters -- some previously proposed and considered and others entirely novel.

Sauer, Kenneth; Yachandra, Vittal K.

2002-04-30

148

A new thermal battery for powering borehole equipment: The discharge performance of Li-Mg-B alloy/LiNO3-KNO3/MnO2 cells at high temperatures  

NASA Astrophysics Data System (ADS)

There is interest in developing a suitable battery system that can be used at temperatures of 250 °C or less to power instrumentation used in oil/gas and geothermal boreholes. The discharge performance of MnO2 cathodes with Li-Mg-B alloy anodes is examined using the LiNO3-KNO3 eutectic electrolyte over a temperature range of 150 °C-300 °C at current densities from 10 to 30 mA cm-2. In this study, we find that the cell can be activated at 150 °C and operate within the desired temperature range without any indication of possible hazards. However, we did observe that temperature and current density significantly affected cell capacity and voltage. Overall, the Li-Mg-B alloy/LiNO3-KNO3/MnO2 system shows great potential for powering instrumentation used in oil/gas and geothermal boreholes.

Niu, Yongqiang; Wu, Zhu; Du, Junlin; Duan, Weiyuan

2014-01-01

149

Revised 06-2011 Rechargeable  

E-print Network

Revised 06-2011 Rechargeable Battery And Cell Phone Recycling Program Guidelines University Waste Label (see separate instructions). Step 4: Bag It Insert a battery or cell phone in a provided bag of Missouri Environmental Health and Safety 573-882-3736 http://ehs.missouri.edu/ hazmat

Taylor, Jerry

150

Rechargeable nickel-zinc batteries  

NASA Technical Reports Server (NTRS)

Device proves superiority in having two and one half to three times the energy content of popular lead-zinc or nickel-cadmium batteries. Application to electric utility vehicles improved acceleration rate and nearly doubled driving range between rechargings. Unit contributes substantially toward realization of practical urban electrical automobiles.

Soltis, D. G.

1977-01-01

151

Groundwater recharge from overbank floods  

NASA Astrophysics Data System (ADS)

Overbank flood recharge is increasingly acknowledged as important for estimations of aquifer sustainable yield. The physics of this process in areas with shallow groundwater, however, is not well understood and typically is not included in river or groundwater models. Modeling of the overbank flood recharge process was undertaken using a fully coupled, surface-subsurface flow model to compare the volume of infiltration through a floodplain with varying surface sediment, aquifer, and flood parameters. The infiltration volume was found to increase with the conductance of the clogging layer (represented by a thin veneer of sediments across the floodplain and river bed), flood wave height, peak duration, and aquifer transmissivity and to decrease with increasing water table gradient (positive toward the river). The influence of the flood wave and aquifer hydraulic parameters was more pronounced in systems with sand or loam clogging layers. Irregularities in floodplain elevation had a large effect on infiltration volume. A dimensionless analysis of the flood recharge process identified the factors that limited flood infiltration for each of the modeled scenarios: the clogging layer conductance, unsaturated aquifer storage, or aquifer transmissivity. A dimensionless numberF* was used to predict the limiting factor in floodplain systems. An analytical equation was developed to estimate the infiltration volume for catchments where full numerical modeling is not warranted or applicable. Results from the analytical equation compared favorably with recharge modeled using a more complex numerical model.

Doble, Rebecca C.; Crosbie, Russell S.; Smerdon, Brian D.; Peeters, Luk; Cook, Freeman J.

2012-09-01

152

ARTIFICIAL RECHARGE METHODS OF KARIZ  

Microsoft Academic Search

Kariz is one of the Iranian traditional water harvesting systems. Unfortunately some experts believe that water loss during winter and out of the crop season is the main disadvantage of this method. One of the methods to increase the discharge of kariz, is to recharge the aquifer artificially, where the karez tunnels are dug in them. This can be done

Abdolkarim Behnia

153

The pronounced seasonality of global groundwater recharge  

NASA Astrophysics Data System (ADS)

Groundwater recharged by meteoric water supports human life by providing two billion people with drinking water and by supplying 40% of cropland irrigation. While annual groundwater recharge rates are reported in many studies, fewer studies have explicitly quantified intra-annual (i.e., seasonal) differences in groundwater recharge. Understanding seasonal differences in the fraction of precipitation that recharges aquifers is important for predicting annual recharge groundwater rates under changing seasonal precipitation and evapotranspiration regimes in a warming climate, for accurately interpreting isotopic proxies in paleoclimate records, and for understanding linkages between ecosystem productivity and groundwater recharge. Here we determine seasonal differences in the groundwater recharge ratio, defined here as the ratio of groundwater recharge to precipitation, at 54 globally distributed locations on the basis of 18O/16O and 2H/1H ratios in precipitation and groundwater. Our analysis shows that arid and temperate climates have wintertime groundwater recharge ratios that are consistently higher than summertime groundwater recharge ratios, while tropical groundwater recharge ratios are at a maximum during the wet season. The isotope-based recharge ratio seasonality is consistent with monthly outputs from a global hydrological model (PCR-GLOBWB) for most, but not all locations. The pronounced seasonality in groundwater recharge ratios shown in this study signifies that, from the point of view of predicting future groundwater recharge rates, a unit change in winter (temperate and arid regions) or wet season (tropics) precipitation will result in a greater change to the annual groundwater recharge rate than the same unit change to summer or dry season precipitation.

Jasechko, Scott; Birks, S. Jean; Gleeson, Tom; Wada, Yoshihide; Fawcett, Peter J.; Sharp, Zachary D.; McDonnell, Jeffrey J.; Welker, Jeffrey M.

2014-11-01

154

Dielectric behavior of ternary mixtures: epoxy resin plus titanates (MgTiO3, CaTiO3 or BaTiO3) associated to oxides (CaO, MnO2 or ZnO)  

NASA Astrophysics Data System (ADS)

In the present work, we study the dielectric behavior of various ternary mixtures composed of epoxy resin (RE), of one of three different titanates (barium titanate, BaTiO3; calcium titanate, CaTiO3; magnesium titanate, MgTiO3) respectively with one of three oxides (calcium oxide, CaO; manganese dioxide, MnO2; zinc oxide, ZnO) using time domain reflectometry (TDR). The different composites are mixed at room temperature in different volume fractions keeping the epoxy resin at a constant volume fraction. Several mixture combinations are studied to see the oxides influence on the titanates dielectric behavior in the range from DC to 10 GHz. This is done through the experimental determination of the dielectric constant ?s. A noticeable effect has been recorded at the low frequency and which consists of an increase of this dielectric permittivity when growing the volume fraction of manganese dioxide. One meaningful point of this study is the lowest static conductivity value (8.017 × 10-3/(?m)) being reached with an incursion of 7.5% of MnO2 in a ternary mixture composed of RE, MgTiO3 and MnO2. In addition, the behavior obtained experimentally has been validated by the Lichtenecker modified model. This study interest lies on an application of these materials in microelectronics and particularly in telecommunication components manufacturing.

Bourouba, Nacerdine; Lalla, Khalfa; Martinez Jimenez, Juan Pablo; Bouzit, Nacerdine

2014-01-01

155

Fabrication of Polypyrrole/Graphene Oxide Composite Nanosheets and Their Applications for Cr(VI) Removal in Aqueous Solution  

PubMed Central

In this paper, we report on the simple, reliable synthesis of polypyrrole (PPy)/graphene oxide (GO) composite nanosheets by using sacrificial-template polymerization method. Herein, MnO2 nanoslices were chosen as a sacrificial-template to deposit PPy, which served as the oxidant as well. During the polymerization of pyrrole on surface of GO nanosheets, MnO2 component was consumed incessantly. As a result, the PPy growing on the surface of GO nanosheets has the morphology just like the MnO2 nanoslices. This method can provide the fabrication of PPy nanostructures more easily than conventional route due to its independence of removing template, which usually is a complex and tedious experimental process. The as-prepared PPy/GO composite nanosheets exhibited an enhanced properties for Cr(VI) ions removal in aqueous solution based on the synergy effect. The adsorption capacity of the PPy/GO composite nanosheets is about two times as large as that of conventional PPy nanoparticles. We believe that our findings can open a new and effective avenue to improve the adsorption performance in removing heavy metal ions from waste water. PMID:22927957

Li, Shangkun; Lu, Xiaofeng; Xue, Yanpeng; Lei, Junyu; Zheng, Tian; Wang, Ce

2012-01-01

156

Research on rechargeable oxygen electrodes  

NASA Technical Reports Server (NTRS)

Studies were carried out on a number of factors which may influence the behavior of the platinum electrocatalyst of oxygen electrodes for use in rechargeable metal-oxygen batteries or hydrogen-oxygen fuel cells. The effects of pretreatments for various potentials and added ionic species, which could be present in such systems, were studied with reguard to: (1) the state of surface oxidation, (2) platinum dissolution, (3) the kinetics of oxygen evolution and reduction (including the role of hydrogen peroxide), and (4) changes in porous electrode structure. These studies were carried out on smooth platinum, platinized platinum, and Teflon-bonded platinum black electrodes in carefully purified electrolyte solutions. The main factors which appear to affect rechargeable oxygen electrode performance and life are: (1) the buildup of a refractory anodic layer on extended cycling, and (2) the dissolution of platinum.

Giner, J.; Malachesky, P. A.; Holleck, G.

1971-01-01

157

Electrically rechargeable REDOX flow cell  

NASA Technical Reports Server (NTRS)

A bulk energy storage system is designed with an electrically rechargeable reduction-oxidation (REDOX) cell divided into two compartments by a membrane, each compartment containing an electrode. An anode fluid is directed through the first compartment at the same time that a cathode fluid is directed through the second compartment. Means are provided for circulating the anode and cathode fluids, and the electrodes are connected to an intermittent or non-continuous electrical source, which when operating, supplies current to a load as well as to the cell to recharge it. Ancillary circuitry is provided for disconnecting the intermittent source from the cell at prescribed times and for circulating the anode and cathode fluids according to desired parameters and conditions.

Thaller, L. H. (inventor)

1976-01-01

158

Iron-Air Rechargeable Battery  

NASA Technical Reports Server (NTRS)

Embodiments include an iron-air rechargeable battery having a composite electrode including an iron electrode and a hydrogen electrode integrated therewith. An air electrode is spaced from the iron electrode and an electrolyte is provided in contact with the air electrode and the iron electrodes. Various additives and catalysts are disclosed with respect to the iron electrode, air electrode, and electrolyte for increasing battery efficiency and cycle life.

Narayan, Sri R. (Inventor); Prakash, G.K. Surya (Inventor); Kindler, Andrew (Inventor)

2014-01-01

159

Groundwater recharge and agricultural contamination  

USGS Publications Warehouse

Agriculture has had direct and indirect effects on the rates and compositions of groundwater recharge and aquifer biogeochemistry. Direct effects include dissolution and transport of excess quantities of fertilizers and associated materials and hydrologic alterations related to irrigation and drainage. Some indirect effects include changes in water-rock reactions in soils and aquifers caused by increased concentrations of dissolved oxidants, protons, and major ions. Agrilcultural activities have directly or indirectly affected the concentrations of a large number of inorganic chemicals in groundwater, for example NO3-, N2, Cl, SO42-, H+, P, C, K, Mg, Ca, Sr, Ba, Ra, and As, as well a wide variety of pesticides and other organic compounds. For reactive contaminants like NO3-, a combination of chemical, isotopic, and environmental-tracer analytical approaches might be required to resolve changing inputs from subsequent alterations as causes of concentration gradients in groundwater. Groundwater records derived from multi-component hydrostratigraphic data can be used to quantify recharge rates and residence times of water and dissolved contaminants, document past variations in recharging contaminant loads, and identify natural contaminant-remediation processes. These data indicate that many of the world's surficial aquifers contain transient records of changing agricultural contamination from the last half of the 20th century. The transient agricultural groundwater signal has important implications for long-term trends and spatial heterogeneity in discharge.

Böhlke, J.K.

2002-01-01

160

Identifying Recharge Location Using Noble Gas Recharge Temperatures, Pajarito Plateau, New Mexico  

NASA Astrophysics Data System (ADS)

The solubility of noble gases in water is temperature dependent. Noble gas concentrations in ground water can therefore be used to determine the temperature at the water table at the recharge location (recharge temperature). The Pajarito Plateau in Northern New Mexico is an example of a hydrogeologic setting where noble gas recharge temperatures provide valuable information about recharge location which could be utilized in numerical model calibration. Previous studies have identified two potentially significant components of recharge to the regional aquifer underlying the plateau: (1) infiltration of precipitation in the Jemez Mountains adjacent to the plateau (mountain-block recharge); and (2) infiltration of stream water in the bottoms of canyons that traverse the plateau (plateau recharge). However, results regarding the relative importance of these two components are conflicting and uncertain. Their relative magnitude is of particular concern because Los Alamos National Laboratory is located on the plateau, and the susceptibility of the regional aquifer to lab-generated wastes depends directly upon the amount of plateau recharge. The Pajarito Plateau is an ideal location for applying noble gas recharge thermometry; mountain-block recharge should have cool recharge temperatures (<12°C) due to the shallow water table in the mountains, whereas plateau recharge should have distinctly warmer recharge temperatures (18 to 21°C) due to water table depths of 200 to 300m on the plateau. Noble gas samples were collected from wells screened in the regional aquifer across the plateau. Those analyzed to date from wells screened in the upper 30m of the aquifer yield recharge temperatures of 18 to 23°C. Exceptions are two wells located within 2km of the mountain front, which have recharge temperatures of 12 and 13°C. The one sample analyzed to date from a well screened deeper in the aquifer (125m below the water table) yields a recharge temperature of 11°C. Preliminary results therefore suggest that plateau recharge comprises nearly all of the water in the upper 30m of the regional aquifer throughout much of the plateau. However, the cooler recharge temperatures closer to the mountains and at depth indicate that mountain-block recharge may still constitute most of the total recharge to the aquifer; plateau recharge may be limited to a thin layer along the top of the aquifer at distances >2km from the mountain front.

Manning, A. H.; Dale, M.

2008-12-01

161

Electrically rechargeable redox flow cells  

NASA Technical Reports Server (NTRS)

Considering the topographical and sizing requirements for a typical pumped water storage installation and the immergence of energy conversion schemes that are time dependent as to their generating capability, a closer look is being given to nonpumped water storage schemes for storing electricity. An electrochemical bulk power storage concept, which was named a rechargeable redox flow cell is described. This scheme, based on pumping a redox couple through a power conversion section, appears to offer high overall efficiency, no cycle life limitations for the electrodes, and deep discharger capability.

Thaller, L. H.

1974-01-01

162

Electrically rechargeable redox flow cells  

NASA Technical Reports Server (NTRS)

Considering the topographical and sizing requirements for a typical pumped water storage installation and the immergence of energy conversion schemes that are time-dependent as to their generating capability, a closer look is being given to nonpumped water storage schemes for storing electricity. An electrochemical bulk power storage concept, called a rechargeable redox flow cell, is described. This scheme, based on pumping a redox couple through a power conversion section, appears to offer high overall efficiency, no cycle life limitations for the electrodes, and deep discharge capability.

Thaller, L. H.

1974-01-01

163

High-efficient treatment of wastewater contained the carcinogen naphthylamine by electrochemical oxidation with ?-Al2O3 supported MnO2 and Sb-doped SnO2 catalyst.  

PubMed

1-Naphthylamine wastewater causes severe environmental pollution because of its acute toxicity and carcinogenicity in humans, which makes it difficult to reuse by conventional technologies. In this study, we report an investigation of the electrochemical catalytic oxidation of 1-naphthylamine in synthetic wastewater in a 150 mL electrolytic batch reactor with Ti/Sb-SnO(2)/PbO(2) as anode and steel plate as cathode, where the reaction was assisted by MnO(2) and Sn(1-x)Sb(x)O(2) composite materials as the catalyst and ?-Al(2)O(3) as the carrier (MnO(2)-Sn(1-x)Sb(x)O(2)/?-Al(2)O(3)). The catalyst was synthesized by impregnating process and was characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The effects of pH and current density on the efficiency of the electrochemical degradation process were also studied. It was found that MnO(2)-Sn(1-x)Sb(x)O(2)/?-Al(2)O(3) exhibited excellent catalytic activity in the electrochemical degradation of 1-naphthylamine wastewater. The results showed that the refractory organics in wastewater can be effectively removed by this process, and a chemical oxygen demand (COD) removal efficiency of 92.2% was obtained in 20 min at pH 7.0 and current density was equal to 50 mA cm(-2). According to the experimental results, a hypothetical mechanism of electrochemical catalytic degradation was also proposed. PMID:22652320

Chen, Fengtao; Yu, Sanchuan; Dong, Xiaoping; Zhang, Shishen

2012-08-15

164

Transformer Recharging with Alpha Channeling in Tokamaks  

SciTech Connect

Transformer recharging with lower hybrid waves in tokamaks can give low average auxiliary power if the resistivity is kept high enough during the radio frequency (rf) recharging stage. At the same time, operation in the hot ion mode via alpha channeling increases the effective fusion reactivity. This paper will address the extent to which these two large cost saving steps are compatible. __________________________________________________

N.J. Fisch

2009-12-21

165

INTRODUCTION TO ARTIFICIAL GROUND-WATER RECHARGE  

EPA Science Inventory

Artificial ground-water recharge has been practiced for scores of years throughout the world. The purpose of artificial recharge is to increase the rate at which water infiltrates the land surface in order to supplement the quantity of ground water in storage. A variety of rechar...

166

NORTH CAROLINA GROUNDWATER RECHARGE RATES 1994  

EPA Science Inventory

North Carolina Groundwater Recharge Rates, from Heath, R.C., 1994, Ground-water recharge in North Carolina: North Carolina State University, as prepared for the NC Department of Environment, Health and Natural Resources (NC DEHNR) Division of Enviromental Management Groundwater S...

167

Recharge at the Hanford Site: Status report  

SciTech Connect

A variety of field programs designed to evaluate recharge and other water balance components including precipitation, infiltration, evaporation, and water storage changes, have been carried out at the Hanford Site since 1970. Data from these programs have indicated that a wide range of recharge rates can occur depending upon specific site conditions. Present evidence suggests that minimum recharge occurs where soils are fine-textured and surfaces are vegetated with deep-rooted plants. Maximum recharge occurs where coarse soils or gravels exist at the surface and soils are kept bare. Recharge can occur in areas where shallow-rooted plants dominate the surface, particularly where soils are coarse-textured. Recharge estimates have been made for the site using simulation models. A US Geological Survey model that attempts to account for climate variability, soil storage parameters, and plant factors has calculated recharge values ranging from near zero to an average of about 1 cm/yr for the Hanford Site. UNSAT-H, a deterministic model developed for the site, appears to be the best code available for estimating recharge on a site-specific basis. Appendix I contains precipitation data from January 1979 to June 1987. 42 refs., 11 figs., 11 tabs.

Gee, G.W.

1987-11-01

168

Groundwater Recharge in the Southern High Plains  

E-print Network

i Draft Groundwater Recharge in the Southern High Plains Report ###, Appendix A By Robert C. Reedy P.O. Box 13231 Austin, TX 78711-3231 1(512) 936-0861 January, 2003 #12;ii Table of Contents Page................................................................................. 1 Recharge Estimation for Current Groundwater Availability Modeling Project

Scanlon, Bridget R.

169

High power rechargeable batteries Paul V. Braun  

E-print Network

High power rechargeable batteries Paul V. Braun , Jiung Cho, James H. Pikul, William P. King storage Secondary batteries High energy density High power density Lithium ion battery 3D battery of rechargeable (second- ary) batteries, as this is critical for most applications. As the penetration

Braun, Paul

170

Reflections on Dry-Zone Recharge  

NASA Astrophysics Data System (ADS)

Quantifying recharge in regions of low precipitation remains a challenging task. The design of permanent nuclear-waste isolation at Yucca Mountain, Nevada, the design of arid-site landfill covers and the pumping of groundwater in desert cities, like Las Vegas, are examples where accurate recharge estimates are needed because they affect billion-dollar decisions. Recharge cannot be measured directly and must rely on estimation methods of various kinds including chemical tracers, thermal profiling, lysimetry, and water-balance modeling. Chemical methods, like chloride-mass-balance can significantly underestimate actual recharge rates and water-balance models are generally limited by large uncertainties. Studies at the U. S. Department of Energy's Hanford Site in Washington State, USA illustrate how estimates of recharge rates have changed over time and how these estimates can affect waste management decisions. Lysimetry has provided reliable estimates of recharge for a wide range of surface condittions. Lysimetric observations of reduced recharge, resulting from advective drying of coarse rock piles, suggest a way to avoid costly recharge protection using titanium shields at Yucca Mountain. The Pacific Northwest National Laboratory is funded by the U. S. Department of Energy under contract DE-AC05-76-RL01830.

Gee, G. W.

2005-05-01

171

Lithium ion rechargeable systems studies  

NASA Astrophysics Data System (ADS)

Lithium ion systems, although relatively new, have attracted much interest worldwide. Their high energy density, long cycle life and relative safety, compared with metallic lithium rechargeable systems, make them prime candidates for powering portable electronic equipment. Although lithium ion cells are presently used in a few consumer devices, e.g., portable phones, camcorders, and laptop computers, there is room for considerable improvement in their performance. Specific areas that need to be addressed include: (1) carbon anode-increase reversible capacity, and minimize passivation; (2) cathode-extend cycle life, improve rate capability, and increase capacity. There are several programs ongoing at Sandia National Laboratories which are investigating means of achieving the stated objectives in these specific areas. This paper will review these programs.

Levy, Samuel C.; Lasasse, Robert R.; Cygan, Randall T.; Voigt, James A.

172

Rechargeable lithium-ion cell  

DOEpatents

The invention relates to a rechargeable lithium-ion cell, a method for its manufacture, and its application. The cell is distinguished by the fact that it has a metallic housing (21) which is electrically insulated internally by two half shells (15), which cover electrode plates (8) and main output tabs (7) and are composed of a non-conductive material, where the metallic housing is electrically insulated externally by means of an insulation coating. The cell also has a bursting membrane (4) which, in its normal position, is located above the electrolyte level of the cell (1). In addition, the cell has a twisting protection (6) which extends over the entire surface of the cover (2) and provides centering and assembly functions for the electrode package, which comprises the electrode plates (8).

Bechtold, Dieter (Bad Vilbel, DE); Bartke, Dietrich (Kelkheim, DE); Kramer, Peter (Konigstein, DE); Kretzschmar, Reiner (Kelkheim, DE); Vollbert, Jurgen (Hattersheim, DE)

1999-01-01

173

Lithium ion rechargeable systems studies  

SciTech Connect

Lithium ion systems, although relatively new, have attracted much interest worldwide. Their high energy density, long cycle life and relative safety, compared with metallic lithium rechargeable systems, make them prime candidates for powering portable electronic equipment. Although lithium ion cells are presently used in a few consumer devices, e.g., portable phones, camcorders, and laptop computers, there is room for considerable improvement in their performance. Specific areas that need to be addressed include: (1) carbon anode--increase reversible capacity, and minimize passivation; (2) cathode--extend cycle life, improve rate capability, and increase capacity. There are several programs ongoing at Sandia National Laboratories which are investigating means of achieving the stated objectives in these specific areas. This paper will review these programs.

Levy, S.C.; Lasasse, R.R.; Cygan, R.T.; Voigt, J.A.

1995-02-01

174

Groundwater recharge estimation and regionalization: the Great Bend Prairie of central Kansas and its recharge statistics  

Microsoft Academic Search

Sophocleous, M., 1992. Groundwater recharge estimation and regionalization: the Great Bend Prairie of central Kansas and its recharge statistics. J. Hydrol., 137: 113-140. The results of a 6 year recharge st,dy in the Great Bend Prairie of t:entral Kansas are statistically analyzed to regionalize the limited number of site-specific but year-round measurements. Emphasis is placed on easily measured parameters and

Marios Sophocleous

1992-01-01

175

Experimental studies in natural groundwater-recharge dynamics: The analysis of observed recharge events  

Microsoft Academic Search

Sophocleous, M. and Perry, C.A., 1985. Experimental studies in natural groundwater- recharge dynamics: The analysis of observed recharge events. J. Hydrol., 81 : 297--332. The amounts and time distribution of groundwater recharge from precipitation over an approximately 19-month period were investigated at two instrumented sites in south- central Kansas. Precipitation and evapotranspiration sequences, soil-moisture profiles and storage changes, water fluxes

MARIOS SOPHOCLEOUS; CHARLES A. PERRY

1985-01-01

176

Design of an AUV recharging system  

E-print Network

The Odyssey AUV Series uses a Lithium-ion Polymer battery which is able to supply the necessary power for a limited mission time. The current method of recharge includes surfacing the AUV, opening the vehicle, removing the ...

Miller, Bryan D. (Bryan David)

2005-01-01

177

REVISED NORTH CAROLINA GROUNDWATER RECHARGE RATES 1998  

EPA Science Inventory

Revised North Carolina Groundwater Recharge Rates, from Heath, R.C., 1994, unpublished map: North Carolina State University, as modified by the NC Department of Environment and Natural Resources (DENR) Division of Water Quality (DWQ) Groundwater Section, (polygons)...

178

Design of an AUV recharging system  

E-print Network

The utility of present Autonomous Underwater Vehicles (AUVs) is limited by their on-board energy storage capability. Research indicates that rechargeable batteries will continue to be the AUV power source of choice for at ...

Gish, Lynn Andrew

2004-01-01

179

Issues and challenges facing rechargeable lithium batteries.  

PubMed

Technological improvements in rechargeable solid-state batteries are being driven by an ever-increasing demand for portable electronic devices. Lithium-ion batteries are the systems of choice, offering high energy density, flexible and lightweight design, and longer lifespan than comparable battery technologies. We present a brief historical review of the development of lithium-based rechargeable batteries, highlight ongoing research strategies, and discuss the challenges that remain regarding the synthesis, characterization, electrochemical performance and safety of these systems. PMID:11713543

Tarascon, J M; Armand, M

2001-11-15

180

Issues and challenges facing rechargeable lithium batteries  

Microsoft Academic Search

Technological improvements in rechargeable solid-state batteries are being driven by an ever-increasing demand for portable electronic devices. Lithium-ion batteries are the systems of choice, offering high energy density, flexible and lightweight design, and longer lifespan than comparable battery technologies. We present a brief historical review of the development of lithium-based rechargeable batteries, highlight ongoing research strategies, and discuss the challenges

J.-M. Tarascon; M. Armand

2001-01-01

181

Theory of the generalized chloride mass balance method for recharge estimation in groundwater basins characterised by point and diffuse recharge  

NASA Astrophysics Data System (ADS)

Application of the conventional chloride mass balance (CMB) method to point recharge dominant groundwater basins can substantially under-estimate long-term average annual recharge by not accounting for the effects of localized surface water inputs. This is because the conventional CMB method ignores the duality of infiltration and recharge found in karstic systems, where point recharge can be a contributing factor. When point recharge is present in groundwater basins, recharge estimation is unsuccessful using the conventional CMB method with, either unsaturated zone chloride or groundwater chloride. In this paper we describe a generalized CMB that can be applied to groundwater basins with point recharge. Results from this generalized CMB are shown to be comparable with long-term recharge estimates obtained using the watertable fluctuation method, groundwater flow modelling and Darcy flow calculations. The generalized CMB method provides an alternative, reliable long-term recharge estimation method for groundwater basins characterised by both point and diffuse recharge.

Somaratne, N.; Smettem, K. R. J.

2014-01-01

182

Proposed artificial recharge studies in northern Qatar  

USGS Publications Warehouse

The aquifer system in northern Qatar comprises a water-table aquifer in the Rus Formation which is separated by an aquitard from a partially confined aquifer in the top of the overlying Umm er Radhuma Formation. These two aquifers are composed of limestone and dolomite of Eocene and Paleocene age and contain a fragile lens of freshwater which is heavily exploited as a source of water for agricultural irrigation. Net withdrawals are greatly in excess of total recharge, and quality of ground water is declining. Use of desalinated seawater for artificial recharge has been proposed for the area. Artificial recharge, on a large scale, could stabilize the decline in ground-water quality while allowing increased withdrawals for irrigation. The proposal appears technically feasible. Recharge should be by injection to the Umm er Radhuma aquifer whose average transmissivity is about 2,000 meters squared per day (as compared to an average of about 200 meters squared per day for the Rus aquifer). Implementation of artificial recharge should be preceded by a hydrogeologic appraisal. These studies should include test drilling, conventional aquifer tests, and recharge-recovery tests at four sites in northern Qatar. (USGS)

Kimrey, J.O.

1985-01-01

183

The Li-ion rechargeable battery: a perspective.  

PubMed

Each cell of a battery stores electrical energy as chemical energy in two electrodes, a reductant (anode) and an oxidant (cathode), separated by an electrolyte that transfers the ionic component of the chemical reaction inside the cell and forces the electronic component outside the battery. The output on discharge is an external electronic current I at a voltage V for a time ?t. The chemical reaction of a rechargeable battery must be reversible on the application of a charging I and V. Critical parameters of a rechargeable battery are safety, density of energy that can be stored at a specific power input and retrieved at a specific power output, cycle and shelf life, storage efficiency, and cost of fabrication. Conventional ambient-temperature rechargeable batteries have solid electrodes and a liquid electrolyte. The positive electrode (cathode) consists of a host framework into which the mobile (working) cation is inserted reversibly over a finite solid-solution range. The solid-solution range, which is reduced at higher current by the rate of transfer of the working ion across electrode/electrolyte interfaces and within a host, limits the amount of charge per electrode formula unit that can be transferred over the time ?t = ?t(I). Moreover, the difference between energies of the LUMO and the HOMO of the electrolyte, i.e., electrolyte window, determines the maximum voltage for a long shelf and cycle life. The maximum stable voltage with an aqueous electrolyte is 1.5 V; the Li-ion rechargeable battery uses an organic electrolyte with a larger window, which increase the density of stored energy for a given ?t. Anode or cathode electrochemical potentials outside the electrolyte window can increase V, but they require formation of a passivating surface layer that must be permeable to Li(+) and capable of adapting rapidly to the changing electrode surface area as the electrode changes volume during cycling. A passivating surface layer adds to the impedance of the Li(+) transfer across the electrode/electrolyte interface and lowers the cycle life of a battery cell. Moreover, formation of a passivation layer on the anode robs Li from the cathode irreversibly on an initial charge, further lowering the reversible ?t. These problems plus the cost of quality control of manufacturing plague development of Li-ion rechargeable batteries that can compete with the internal combustion engine for powering electric cars and that can provide the needed low-cost storage of electrical energy generated by renewable wind and/or solar energy. Chemists are contributing to incremental improvements of the conventional strategy by investigating and controlling electrode passivation layers, improving the rate of Li(+) transfer across electrode/electrolyte interfaces, identifying electrolytes with larger windows while retaining a Li(+) conductivity ?(Li) > 10(-3) S cm(-1), synthesizing electrode morphologies that reduce the size of the active particles while pinning them on current collectors of large surface area accessible by the electrolyte, lowering the cost of cell fabrication, designing displacement-reaction anodes of higher capacity that allow a safe, fast charge, and designing alternative cathode hosts. However, new strategies are needed for batteries that go beyond powering hand-held devices, such as using electrode hosts with two-electron redox centers; replacing the cathode hosts by materials that undergo displacement reactions (e.g. sulfur) by liquid cathodes that may contain flow-through redox molecules, or by catalysts for air cathodes; and developing a Li(+) solid electrolyte separator membrane that allows an organic and aqueous liquid electrolyte on the anode and cathode sides, respectively. Opportunities exist for the chemist to bring together oxide and polymer or graphene chemistry in imaginative morphologies. PMID:23294028

Goodenough, John B; Park, Kyu-Sung

2013-01-30

184

Raising the cycling stability of aqueous lithium-ion batteries by eliminating oxygen in the electrolyte  

Microsoft Academic Search

Aqueous lithium-ion batteries may solve the safety problem associated with lithium-ion batteries that use highly toxic and flammable organic solvents, and the poor cycling life associated with commercialized aqueous rechargeable batteries such as lead-acid and nickel-metal hydride systems. But all reported aqueous lithium-ion battery systems have shown poor stability: the capacity retention is typically less than 50% after 100 cycles.

Jia-Yan Luo; Wang-Jun Cui; Ping He; Yong-Yao Xia

2010-01-01

185

Phase transitions and thermotropic phase boundaries in MnO2-doped (K0.5Na0.5)NbO3-0.05LiNbO3 single crystals: Raman scattering evidence at elevated temperatures  

NASA Astrophysics Data System (ADS)

Raman scattering of (K0.5Na0.5)NbO3-0.05LiNbO3-yMnO2 (y = 0% and 1.0%) single crystals have been reported in the temperature range from 300 to 800 K. The spectra exhibit a competition between a soft mode and a relaxation mode upon heating across the diverse transitions. The progressive change in the conflicting displacive mechanism (soft mode) and order-disorder (relaxation mode) can explain the origin of the successive orthorhombic-tetragonal-cubic phase transitions. Moreover, the polymorphic phase transition between orthorhombic and tetragonal structures can be confirmed through the observation of thermotropic phase boundaries for MnO2-doped (K0.5Na0.5)NbO3-0.05LiNbO3 single crystals.

Xu, L. P.; Jiang, K.; Zhang, J. Z.; Xu, G. S.; Hu, Z. G.; Chu, J. H.

2015-03-01

186

A bi-functional device for self-powered electrochromic window and self-rechargeable transparent battery applications  

NASA Astrophysics Data System (ADS)

Electrochromic smart windows are regarded as a good choice for green buildings. However, conventional devices need external biases to operate, which causes additional energy consumption. Here we report a self-powered electrochromic window, which can be used as a self-rechargeable battery. We use aluminium to reduce Prussian blue (PB, blue in colour) to Prussian white (PW, colourless) in potassium chloride electrolyte, realizing a device capable of self-bleaching. Interestingly, the device can be self-recovered (gaining blue appearance again) by simply disconnecting the aluminium and PB electrodes, which is due to the spontaneous oxidation of PW to PB by the dissolved oxygen in aqueous solution. The self-operated bleaching and colouration suggest another important function of the device: a self-rechargeable transparent battery. Thus the PB/aluminium device we report here is bifunctional, that is, it is a self-powered electrochromic window as well as a self-rechargeable transparent battery.

Wang, Jinmin; Zhang, Lei; Yu, Le; Jiao, Zhihui; Xie, Huaqing; Lou, Xiong Wen (David); Wei Sun, Xiao

2014-09-01

187

A bi-functional device for self-powered electrochromic window and self-rechargeable transparent battery applications.  

PubMed

Electrochromic smart windows are regarded as a good choice for green buildings. However, conventional devices need external biases to operate, which causes additional energy consumption. Here we report a self-powered electrochromic window, which can be used as a self-rechargeable battery. We use aluminium to reduce Prussian blue (PB, blue in colour) to Prussian white (PW, colourless) in potassium chloride electrolyte, realizing a device capable of self-bleaching. Interestingly, the device can be self-recovered (gaining blue appearance again) by simply disconnecting the aluminium and PB electrodes, which is due to the spontaneous oxidation of PW to PB by the dissolved oxygen in aqueous solution. The self-operated bleaching and colouration suggest another important function of the device: a self-rechargeable transparent battery. Thus the PB/aluminium device we report here is bifunctional, that is, it is a self-powered electrochromic window as well as a self-rechargeable transparent battery. PMID:25247385

Wang, Jinmin; Zhang, Lei; Yu, Le; Jiao, Zhihui; Xie, Huaqing; Lou, Xiong Wen David; Sun, Xiao Wei

2014-01-01

188

Estimated recharge rates at the Hanford Site  

SciTech Connect

The Ground-Water Surveillance Project monitors the distribution of contaminants in ground water at the Hanford Site for the U.S. Department of Energy. A subtask called {open_quotes}Water Budget at Hanford{close_quotes} was initiated in FY 1994. The objective of this subtask was to produce a defensible map of estimated recharge rates across the Hanford Site. Methods that have been used to estimate recharge rates at the Hanford Site include measurements (of drainage, water contents, and tracers) and computer modeling. For the simulations of 12 soil-vegetation combinations, the annual rates varied from 0.05 mm/yr for the Ephrata sandy loam with bunchgrass to 85.2 mm/yr for the same soil without vegetation. Water content data from the Grass Site in the 300 Area indicated that annual rates varied from 3.0 to 143.5 mm/yr during an 8-year period. The annual volume of estimated recharge was calculated to be 8.47 {times} 10{sup 9} L for the potential future Hanford Site (i.e., the portion of the current Site bounded by Highway 240 and the Columbia River). This total volume is similar to earlier estimates of natural recharge and is 2 to 10x higher than estimates of runoff and ground-water flow from higher elevations. Not only is the volume of natural recharge significant in comparison to other ground-water inputs, the distribution of estimated recharge is highly skewed to the disturbed sandy soils (i.e., the 200 Areas, where most contaminants originate). The lack of good estimates of the means and variances of the supporting data (i.e., the soil map, the vegetation/land use map, the model parameters) translates into large uncertainties in the recharge estimates. When combined, the significant quantity of estimated recharge, its high sensitivity to disturbance, and the unquantified uncertainty of the data and model parameters suggest that the defensibility of the recharge estimates should be improved.

Fayer, M.J.; Walters, T.B.

1995-02-01

189

Transient, spatially varied groundwater recharge modeling  

NASA Astrophysics Data System (ADS)

The objective of this work is to integrate field data and modeling tools in producing temporally and spatially varying groundwater recharge in a pilot watershed in North Okanagan, Canada. The recharge modeling is undertaken by using the Richards equation based finite element code (HYDRUS-1D), ArcGIS™, ROSETTA, in situ observations of soil temperature and soil moisture, and a long-term gridded climate data. The public version of HYDUS-1D and another version with detailed freezing and thawing module are first used to simulate soil temperature, snow pack, and soil moisture over a one year experimental period. Statistical analysis of the results show both versions of HYDRUS-1D reproduce observed variables to the same degree. After evaluating model performance using field data and ROSETTA derived soil hydraulic parameters, the HYDRUS-1D code is coupled with ArcGIS™ to produce spatially and temporally varying recharge maps throughout the Deep Creek watershed. Temporal and spatial analysis of 25 years daily recharge results at various representative points across the study watershed reveal significant temporal and spatial variations; average recharge estimated at 77.8 ± 50.8 mm/year. Previous studies in the Okanagan Basin used Hydrologic Evaluation of Landfill Performance without any attempt of model performance evaluation, notwithstanding its inherent limitations. Thus, climate change impact results from this previous study and similar others, such as Jyrkama and Sykes (2007), need to be interpreted with caution.

Assefa, Kibreab Amare; Woodbury, Allan D.

2013-08-01

190

Solar recharging system for hearing aid cells.  

PubMed

We present a solar recharging system for nickel-cadmium cells of interest in areas where batteries for hearing aids are difficult to obtain. The charger has sun cells at the top. Luminous energy is converted into electrical energy, during the day and also at night if there is moonlight. The cost of the charger and hearing aid is very low at 35 US$. The use of solar recharging for hearing aids would be useful in alleviating the problems of deafness in parts of developing countries where there is no electricity. PMID:7964140

Gòmez Estancona, N; Tena, A G; Torca, J; Urruticoechea, L; Muñiz, L; Aristimuño, D; Unanue, J M; Torca, J; Urruticoechea, A

1994-09-01

191

Characteristics of groundwater recharge on the North China Plain.  

PubMed

Groundwater recharge is an important component of the groundwater system. On the North China Plain (NCP), groundwater is the main water supply. Because of large-scale overexploitation, the water table has declined, which has produced severe adverse effects on the environment and ecosystem. In this article, tracer experiment and watershed model were used to calculate and analyze NCP groundwater recharge. In the tracer experiment, average recharge was 108 mm/year and recharge coefficient 0.16. With its improved irrigation, vegetation coverage and evapotranspiration modules, the INFIL3.0 model was used for calculation of groundwater recharge. Regional modeling results showed an average recharge of 102 mm/year and recharge coefficient 0.14, for 2001-2009. These values are very similar to those from the field tracer experiment. Influences in the two methods were analyzed. The results can provide an important reference for NCP groundwater recharge. PMID:24032445

Tan, Xiu-Cui; Wu, Jing-Wei; Cai, Shu-Ying; Yang, Jin-Zhong

2014-01-01

192

Groundwater Recharge in Texas Bridget R. Scanlon, Alan Dutton,  

E-print Network

................................................................................. 28 Ogallala Aquifer ............................................................................. 20 Recharge Rates for the Major Aquifers Based on Review of Existing Data .................... 21 Evaluation of Techniques Used to Quantify Recharge in the Major Aquifers ................. 22 Conceptual

Scanlon, Bridget R.

193

REFLEAK: NIST Leak/Recharge Simulation Program for Refrigerant Mixtures  

National Institute of Standards and Technology Data Gateway

SRD 73 NIST REFLEAK: NIST Leak/Recharge Simulation Program for Refrigerant Mixtures (PC database for purchase)   REFLEAK estimates composition changes of zeotropic mixtures in leak and recharge processes.

194

Sources of uncertainty in climate change impacts on groundwater recharge  

Microsoft Academic Search

This paper assesses the significance of the many sources of uncertainty in future groundwater recharge estimation, based on lessons learnt from an integrated approach to assessing the regional impacts of climate and socio-economic change on groundwater recharge in East Anglia, UK. Many factors affect simulations of future groundwater recharge including changed precipitation and temperature regimes, coastal flooding, urbanization, woodland establishment,

I. P. Holman

2007-01-01

195

Anode for rechargeable ambient temperature lithium cells  

NASA Technical Reports Server (NTRS)

An ambient room temperature, high density, rechargeable lithium battery includes a Li(x)Mg2Si negative anode which intercalates lithium to form a single crystalline phase when x is up to 1.0 and an amorphous phase when x is from 1 to 2.0. The electrode has good reversibility and mechanical strength after cycling.

Huang, Chen-Kuo (inventor); Surampudi, Subbarao (inventor); Attia, Alan I. (inventor); Halpert, Gerald (inventor)

1994-01-01

196

Recharging "Hot-Melt" Adhesive Film  

NASA Technical Reports Server (NTRS)

Technique for recharging surface with "hot-melt" film makes use of one sided, high-temperature, pressure-sensitive adhesive tape. Purpose of the one-sided tape is to hold hot-melt charge in place until fused to surface. After adhesive has fused to surface and cooled, tape is removed, leaving adhesive on surface.

Progar, D. J.

1983-01-01

197

Design considerations for rechargeable lithium batteries  

NASA Technical Reports Server (NTRS)

Viewgraphs of a discussion of design considerations for rechargable lithium batteries. The objective is to determine the influence of cell design parameters on the performance of Li-TiS2 cells. Topics covered include cell baseline design and testing, cell design and testing, cell design parameters studies, and cell cycling performance.

Shen, D. H.; Huang, C.-K.; Davies, E.; Perrone, D.; Surampudi, S.; Halpert, Gerald

1993-01-01

198

Self-Recharging Virtual Currency David Irwin  

E-print Network

aydan@cs.duke.edu ABSTRACT Market-based control is attractive for networked computing utilities in which self-recharging virtual currency model as a com- mon medium of exchange in a computational market. The key idea is to recycle currency through the economy auto- matically while bounding the rate

Shenoy, Prashant

199

Alloys of clathrate allotropes for rechargeable batteries  

DOEpatents

The present disclosure is directed at an electrode for a battery wherein the electrode comprises clathrate alloys of silicon, germanium or tin. In method form, the present disclosure is directed at methods of forming clathrate alloys of silicon, germanium or tin which methods lead to the formation of empty cage structures suitable for use as electrodes in rechargeable type batteries.

Chan, Candace K; Miller, Michael A; Chan, Kwai S

2014-12-09

200

Groundwater Recharge Simulator M. Tech. Thesis  

E-print Network

Groundwater Recharge Simulator M. Tech. Thesis by Dharmvir Kumar Roll No: 07305902 Guide: Prof;Contents 1 Introduction 1 1.1 Groundwater Theory.1.2 Unsaturated Flow and the Water Table . . . . . . . . . . . . . . . . 7 1.1.3 Some more Terminology

Sohoni, Milind

201

An approach to identify urban groundwater recharge  

NASA Astrophysics Data System (ADS)

Evaluating the proportion in which waters from different origins are mixed in a given water sample is relevant for many hydrogeological problems, such as quantifying total recharge, assessing groundwater pollution risks, or managing water resources. Our work is motivated by urban hydrogeology, where waters with different chemical signature can be identified (losses from water supply and sewage networks, infiltration from surface runoff and other water bodies, lateral aquifers inflows, ...). The relative contribution of different sources to total recharge can be quantified by means of solute mass balances, but application is hindered by the large number of potential origins. Hence, the need to incorporate data from a large number of conservative species, the uncertainty in sources concentrations and measurement errors. We present a methodology to compute mixing ratios and end-members composition, which consists of (i) Identification of potential recharge sources, (ii) Selection of tracers, (iii) Characterization of the hydrochemical composition of potential recharge sources and mixed water samples, and (iv) Computation of mixing ratios and reevaluation of end-members. The analysis performed in a data set from samples of the Barcelona city aquifers suggests that the main contributors to total recharge are the water supply network losses (22%), the sewage network losses (30%), rainfall, concentrated in the non-urbanized areas (17%), from runoff infiltration (20%), and the Besòs River (11%). Regarding species, halogens (chloride, fluoride and bromide), sulfate, total nitrogen, and stable isotopes (18O2H, and 34S) behaved quite conservatively. Boron, residual alkalinity, EDTA and Zn did not. Yet, including these species in the computations did not affect significantly the proportion estimations.

Vázquez-Suñé, E.; Carrera, J.; Tubau, I.; Sánchez-Vila, X.; Soler, A.

2010-04-01

202

An approach to identify urban groundwater recharge  

NASA Astrophysics Data System (ADS)

Evaluating the proportion in which waters from different origins are mixed in a given water sample is relevant for many hydrogeological problems, such as quantifying total recharge, assessing groundwater pollution risks, or managing water resources. Our work is motivated by urban hydrogeology, where waters with different chemical signature can be identified (losses from water supply and sewage networks, infiltration from surface runoff and other water bodies, lateral aquifers inflows, ...). The relative contribution of different sources to total recharge can be quantified by means of solute mass balances, but application is hindered by the large number of potential origins. Hence, the need to incorporate data from a large number of conservative species, the uncertainty in sources concentrations and measurement errors. We present a methodology to compute mixing ratios and end-members composition, which consists of (i) Identification of potential recharge sources, (ii) Selection of tracers, (iii) Characterization of the hydrochemical composition of potential recharge sources and mixed water samples, and (iv) Computation of mixing ratios and reevaluation of end-members. The analysis performed in a data set from samples of the Barcelona city aquifers suggests that the main contributors to total recharge are the water supply network losses (22%), the sewage network losses (30%), rainfall, concentrated in the non-urbanized areas (17%), from runoff infiltration (20%), and the Besòs River (11%). Regarding species, halogens (chloride, fluoride and bromide), sulfate, total nitrogen, and stable isotopes (18O, 2H, and 34S) behaved quite conservatively. Boron, residual alkalinity, EDTA and Zn did not. Yet, including these species in the computations did not affect significantly the proportion estimations.

Vázquez-Suñé, E.; Carrera, J.; Tubau, I.; Sánchez-Vila, X.; Soler, A.

2010-10-01

203

Manganese oxide cathodes for rechargeable batteries  

NASA Astrophysics Data System (ADS)

Manganese oxides are considered as promising cathodes for rechargeable batteries due to their low cost and low toxicity as well as the abundant natural resources. In this dissertation, manganese oxides have been investigated as cathodes for both rechargeable lithium and alkaline batteries. Nanostructured lithium manganese oxides designed for rechargeable lithium cells have been synthesized by reducing lithium permanganate with methanol or hydrogen in various solvents followed by firing at moderate temperatures. The samples have been characterized by wet-chemical analyses, thermal methods, spectroscopic methods, and electron microscopy. It has been found that chemical residues in the oxides such as carboxylates and hydroxyl groups, which could be controlled by varying the reaction medium, reducing agents, and additives, make a significant influence on the electrochemical properties. The Li/Mn ratio in the material has also been found to be a critical factor in determining the rechargeability of the cathodes. The optimized samples exhibit a high capacity of close to 300 mAh/g with good cyclability and charge efficiency. The high capacity with a lower discharge voltage may make these nanostructured oxides particularly attractive for lithium polymer batteries. The research on the manganese oxide cathodes for alkaline batteries is focused on an analysis of the reaction products generated during the charge/discharge processes or by some designed chemical reactions mimicking the electrochemical processes. The factors influencing the formation of Mn3O4 in the two-electron redox process of delta-MnO2 have been studied with linear sweep voltammetry combined with X-ray diffraction. The presence of bismuth, the discharge rate, and the microstructure of the electrodes are found to affect the formation of Mn3O4, which is known to be electrochemically inactive. A faster voltage sweep and a more intimate mixing of the manganese oxide and carbon in the cathode are found to suppress the formation of Mn3O4. Bismuth has also been found to be beneficial in the one-electron process of gamma-MnO 2 when incorporated into the cathode. The results of a series of chemical reactions reveal that bismuth is blocking some reaction paths leading to the unwanted birnessite or Mn3O4. Barium is also found to play a similar role, but it is less effective than bismuth for the same amount of additive. Optimization of the additives has the potential to make the rechargeable alkaline cells based on manganese oxides to successfully compete with other rechargeable systems due to their low cost, environmental friendliness, and excellent safety features.

Im, Dongmin

204

Rechargeable Infection-responsive Antifungal Denture Materials  

PubMed Central

Candida-associated denture stomatitis (CADS) is a significant clinical concern. We developed rechargeable infection-responsive antifungal denture materials for potentially managing the disease. Polymethacrylic acid (PMAA) was covalently bound onto diurethane dimethacrylate denture resins in the curing step. The PMAA resins bound cationic antifungal drugs such as miconazole and chlorhexidine digluconate (CG) through ionic interactions. The anticandidal activities of the drug-containing PMAA-resin discs were sustained for a prolonged period of time (weeks and months). Drug release was much faster at acidic conditions (pH 5) than at pH 7. Drugs bound to the denture materials could be “washed out” by treatment with EDTA, and the drug-depleted resins could be recharged with the same or a different class of anticandidal drugs. These results suggest clinical potential of the newly developed antifungal denture materials in the management of CADS and other infectious conditions. PMID:20940361

Cao, Z.; Sun, X.; Yeh, C.-K.; Sun, Y.

2010-01-01

205

Nanocomposite polymer electrolyte for rechargeable magnesium batteries  

SciTech Connect

Nanocomposite polymer electrolytes present new opportunities for rechargeable magnesium batteries. However, few polymer electrolytes have demonstrated reversible Mg deposition/dissolution and those that have still contain volatile liquids such as tetrahydrofuran (THF). In this work, we report a nanocomposite polymer electrolyte based on poly(ethylene oxide) (PEO), Mg(BH4)2 and MgO nanoparticles for rechargeable Mg batteries. Cells with this electrolyte have a high coulombic efficiency of 98% for Mg plating/stripping and a high cycling stability. Through combined experiment-modeling investigations, a correlation between improved solvation of the salt and solvent chain length, chelation and oxygen denticity is established. Following the same trend, the nanocomposite polymer electrolyte is inferred to enhance the dissociation of the salt Mg(BH4)2 and thus improve the electrochemical performance. The insights and design metrics thus obtained may be used in nanocomposite electrolytes for other multivalent systems.

Shao, Yuyan; Rajput, Nav Nidhi; Hu, Jian Z.; Hu, Mary Y.; Liu, Tianbiao L.; Wei, Zhehao; Gu, Meng; Deng, Xuchu; Xu, Suochang; Han, Kee Sung; Wang, Jiulin; Nie, Zimin; Li, Guosheng; Zavadil, K.; Xiao, Jie; Wang, Chong M.; Henderson, Wesley A.; Zhang, Jiguang; Wang, Yong; Mueller, Karl T.; Persson, Kristin A.; Liu, Jun

2014-12-28

206

Rechargeable battery-powered flashlight system  

SciTech Connect

A rechargeable battery-operated flashlight system includes a housing for the flashlight, batteries and associated circuitry. A two-pronged plug is rotatably mounted in the housing for movement between two positions, the prongs projecting outwardly through an opening in the housing so that in one position they project into a recess formed by a reentrant portion of the housing and in the other position they project away from the recess. Resilient contacts connect the prongs to the rest of the circuitry, and engage in detents on the prongs in their two positions to inhibit rotation thereof. A wall bracket defines a pocket for releasably accommodating a receptacle fixture for receiving the plug prongs in their one position and for supporting the housing during recharging. In their other position, the prongs can be plugged directly into an AC wall outlet.

Conforti, F.J.; Fenne, K.R.

1984-08-21

207

A new rechargeable intelligent vehicle detection sensor  

NASA Astrophysics Data System (ADS)

Intelligent Transportation System (ITS) is a valid approach to solve the increasing transportation issue in cities. Vehicle detection is one of the key technologies in ITS. The ITS collects and processes traffic data (vehicle flow, vehicular speed, vehicle density and occupancy ratios) from vehicle detection sensors buried under the road or installed along the road. Inductive loop detector as one type of the vehicle detector is applied extensively, with the characters of stability, high value to cost ratio and feasibility. On the other hand, most of the existing inductive loop vehicle detection sensors have some weak points such as friability of detective loop, huge engineering for setting and traffic interruption during installing the sensor. The design and reality of a new rechargeable intelligent vehicle detection sensor is presented in this paper against these weak points existing now. The sensor consists of the inductive loop detector, the rechargeable batteries, the MCU (microcontroller) and the transmitter. In order to reduce the installing project amount, make the loop durable and easily maintained, the volume of the detective loop is reduced as much as we can. Communication in RF (radio frequency) brings on the advantages of getting rid of the feeder cable completely and reducing the installing project amount enormously. For saving the cable installation, the sensor is supplied by the rechargeable batteries. The purpose of the intelligent management of the energy and transmitter by means of MCU is to minimize the power consumption and prolong the working period of the sensor. In a word, the new sensor is more feasible with smaller volume, wireless communication, rechargeable batteries, low power consumption, low cost, high detector precision and easy maintenance and installation.

Lin, L.; Han, X. B.; Ding, R.; Li, G.; C-Y Lu, Steven; Hong, Q.

2005-01-01

208

Ampere-Hour Meter For Rechargeable Battery  

NASA Technical Reports Server (NTRS)

Low-power analog/digital electronic circuit meters discharge of storage battery in ampere-hours. By metering discharge, one obtains indication of state of charge of battery and avoids unnecessary recharging, maintaining capacity of battery and prolonging life. Because of its small size and low power consumption, useful in such applications as portable video cameras, communication equipment on boats, portable audio equipment, and portable medical equipment.

Tripp, John S.; Schott, Timothy D.; Tcheng, Ping

1993-01-01

209

Ionic liquid electrolytes as a platform for rechargeable metal-air batteries: a perspective.  

PubMed

Metal-air batteries are a well-established technology that can offer high energy densities, low cost and environmental responsibility. Despite these favourable characteristics and utilisation of oxygen as the cathode reactant, these devices have been limited to primary applications, due to a number of problems that occur when the cell is recharged, including electrolyte loss and poor efficiency. Overcoming these obstacles is essential to creating a rechargeable metal-air battery that can be utilised for efficiently capturing renewable energy. Despite the first metal-air battery being created over 100 years ago, the emergence of reactive metals such as lithium has reinvigorated interest in this field. However the reactivity of some of these metals has generated a number of different philosophies regarding the electrolyte of the metal-air battery. Whilst much is already known about the anode and cathode processes in aqueous and organic electrolytes, the shortcomings of these electrolytes (i.e. volatility, instability, flammability etc.) have led some of the metal-air battery community to study room temperature ionic liquids (RTILs) as non-volatile, highly stable electrolytes that have the potential to support rechargeable metal-air battery processes. In this perspective, we discuss how some of these initial studies have demonstrated the capabilities of RTILs as metal-air battery electrolytes. We will also show that much of the long-held mechanistic knowledge of the oxygen electrode processes might not be applicable in RTIL based electrolytes, allowing for creative new solutions to the traditional irreversibility of the oxygen reduction reaction. Our understanding of key factors such as the effect of catalyst chemistry and surface structure, proton activity and interfacial reactions is still in its infancy in these novel electrolytes. In this perspective we highlight the key areas that need the attention of electrochemists and battery engineers, in order to progress the understanding of the physical and electrochemical processes in RTILs as electrolytes for the various forms of rechargeable metal-air batteries. PMID:25093926

Kar, Mega; Simons, Tristan J; Forsyth, Maria; MacFarlane, Douglas R

2014-09-21

210

Probabilistic analysis of the effects of climate change on groundwater recharge  

Microsoft Academic Search

Groundwater recharge is likely to be affected by climate change. In semiarid regions where groundwater resources are often critical, annual recharge rates are typically small and most recharge occurs episodically. Such episodic recharge is uncertain and difficult to predict. This paper analyzes the impacts of different climate predictions on diffuse episodic recharge at a low-relief semiarid rain-fed agricultural area. The

Gene-Hua Crystal Ng; Dennis McLaughlin; Dara Entekhabi; Bridget R. Scanlon

2010-01-01

211

A review of groundwater recharge under irrigated agriculture in Australia  

NASA Astrophysics Data System (ADS)

Quantification of recharge under irrigated agriculture is one of the most important but difficult tasks. It is the least understood component in groundwater studies because of its large variability in space and time and the difficulty of direct measurement. Better management of groundwater resources is only possible if we can accurately determine all fluxes going into and out of a groundwater system. One of the major challenges facing irrigated agriculture in Australia, and the world, is to reduce uncertainty in estimating or measuring the recharge flux. Reducing uncertainty in groundwater recharge under irrigated agriculture is a pre-requisite for effective, efficient and sustainable groundwater resource management especially in dry areas where groundwater usage is often the key to economic development. An accurate quantification of groundwater recharge under irrigated systems is also crucial because of its potential impacts on soil profile salinity, groundwater levels and groundwater quality. This paper aims to identify the main recharge control parameters thorough a review of past field and modelling recharge studies in Australia. We find that the main recharge control parameters under irrigated agriculture are soil type, irrigation management, watertable depth, land cover or plant water uptake, soil surface conditions, and soil, irrigation water and groundwater chemistry. The most commonly used recharge estimation approaches include chloride mass balance, water budget equation, lysimeters, Darcy's law and numerical models. Main sources and magnitude of uncertainty in recharge estimates associated with these approaches are discussed.

Riasat, Ali; Mallants, Dirk; Walker, Glen; Silberstein, Richard

2014-05-01

212

Recycling of used Ni-MH rechargeable batteries  

SciTech Connect

The Ni-MH (nickel metal hydride) rechargeable battery was developed several years ago. Its higher electrochemical capacity and greater safety compared with the Ni-Cd rechargeable battery have resulted in very rapid increase in its production. The Ni-MH rechargeable battery consists of Ni, Co and rare earth metals, so that recycling is important to recover these valuable mineral resources. In this study, a basic recycling process for used Ni-MH rechargeable batteries has been developed, in which the Ni, Co and rare earth elements are recovered through a combination of mechanical processing and hydrometallurgical processing.

Yoshida, T.; Ono, H.; Shirai, R. [Mitsui Mining and Smelting Co., Ltd., Ageo, Saitama (Japan). Corporate R and D Center

1995-12-31

213

Making Li-air batteries rechargeable: material challenges  

SciTech Connect

A Li-air battery could potentially provide three to five times higher energy density/specific energy than conventional batteries, thus enable the driving range of an electric vehicle comparable to a gasoline vehicle. However, making Li-air batteries rechargeable presents significant challenges, mostly related with materials. Herein, we discuss the key factors that influence the rechargeability of Li-air batteries with a focus on nonaqueous system. The status and materials challenges for nonaqueous rechargeable Li-air batteries are reviewed. These include electrolytes, cathode (electocatalysts), lithium metal anodes, and oxygen-selective membranes (oxygen supply from air). The perspective of rechargeable Li-air batteries is provided.

Shao, Yuyan; Ding, Fei; Xiao, Jie; Zhang, Jian; Xu, Wu; Park, Seh Kyu; Zhang, Jiguang; Wang, Yong; Liu, Jun

2013-02-25

214

An ultrafast rechargeable aluminium-ion battery.  

PubMed

The development of new rechargeable battery systems could fuel various energy applications, from personal electronics to grid storage. Rechargeable aluminium-based batteries offer the possibilities of low cost and low flammability, together with three-electron-redox properties leading to high capacity. However, research efforts over the past 30 years have encountered numerous problems, such as cathode material disintegration, low cell discharge voltage (about 0.55 volts; ref. 5), capacitive behaviour without discharge voltage plateaus (1.1-0.2 volts or 1.8-0.8 volts) and insufficient cycle life (less than 100 cycles) with rapid capacity decay (by 26-85 per cent over 100 cycles). Here we present a rechargeable aluminium battery with high-rate capability that uses an aluminium metal anode and a three-dimensional graphitic-foam cathode. The battery operates through the electrochemical deposition and dissolution of aluminium at the anode, and intercalation/de-intercalation of chloroaluminate anions in the graphite, using a non-flammable ionic liquid electrolyte. The cell exhibits well-defined discharge voltage plateaus near 2 volts, a specific capacity of about 70 mA h g(-1) and a Coulombic efficiency of approximately 98 per cent. The cathode was found to enable fast anion diffusion and intercalation, affording charging times of around one minute with a current density of ~4,000 mA g(-1) (equivalent to ~3,000 W kg(-1)), and to withstand more than 7,500 cycles without capacity decay. PMID:25849777

Lin, Meng-Chang; Gong, Ming; Lu, Bingan; Wu, Yingpeng; Wang, Di-Yan; Guan, Mingyun; Angell, Michael; Chen, Changxin; Yang, Jiang; Hwang, Bing-Joe; Dai, Hongjie

2015-04-16

215

Artificial recharge of groundwater and its role in water management  

USGS Publications Warehouse

This paper summarizes and discusses the various aspects and methods of artificial recharge with particular emphasis on its uses and potential role in water management in the Arabian Gulf region. Artificial recharge occurs when man's activities cause more water to enter an aquifer, either under pumping or non-pumping conditions, than otherwise would enter the aquifer. Use of artificial recharge can be a practical means of dealing with problems of overdraft of groundwater. Methods of artificial recharge may be grouped under two broad types: (a) water spreading techniques, and (b) well-injection techniques. Successful use of artificial recharge requires a thorough knowledge of the physical and chemical characteristics of the aquifier system, and extensive onsite experimentation and tailoring of the artificial-recharge technique to fit the local or areal conditions. In general, water spreading techniques are less expensive than well injection and large quantities of water can be handled. Water spreading can also result in significant improvement in quality of recharge waters during infiltration and movement through the unsaturated zone and the receiving aquifer. In comparison, well-injection techniques are often used for emplacement of fresh recharge water into saline aquifer zones to form a manageable lens of fresher water, which may later be partially withdrawn for use or continue to be maintained as a barrier against salt-water encroachment. A major advantage in use of groundwater is its availability, on demand to wells, from a natural storage reservoir that is relatively safe from pollution and from damage by sabotage or other hostile action. However, fresh groundwater occurs only in limited quantities in most of the Arabian Gulf region; also, it is heavily overdrafted in many areas, and receives very little natural recharge. Good use could be made of artificial recharge by well injection in replenishing and managing aquifers in strategic locations if sources of freshwater could be made available for the artificial-recharge operations. ?? 1989.

Kimrey, J.O.

1989-01-01

216

Challenges of Artificial Recharge at the Chain of Lakes  

NASA Astrophysics Data System (ADS)

A series of gravel quarry lakes, A through I (i.e. Chain of Lakes) in Alameda County, California are planned to convert to off-channel spreading lakes for artificial groundwater recharge. An operational plan is needed for the near-term improvements that would allow safe and efficient operations of Lake H and Lake I recently acquired for artificial recharge operations. Water source for the groundwater recharge comes from State Water Project (SWP) water releases at the South Bay Aqueduct turnout. The released water flows approximately nine miles in Arroyo Mocho Creek to the planned diversion facility. The recharge system includes multiple water delivery components and recharge components. Reliability of SWP water delivery is a water supply constraint to the recharge system. Hydraulic capacities of each delivery component and recharge capacities of each recharge component are physical constraints to the development of the operational plan. Policy issues identified in the Mitigated Negative Declaration which contains mitigation measures addressing potential impacts of fisheries and erosion are regulatory constraints to the operational plan development. Our approach that addresses technical challenges and policy issues in the development of the operational plan includes i) determination of lake recharge under observed conditions using water budget method; ii) development and calibration of a ground water flow model using MODFLOW; iii) estimation of lake recharge capacity for a range of lake levels using the calibrated ground water flow model; iv) analysis of clogging layer effects on recharge capacity; and v) development and application of operations models for the stream delivery system and the lake system.

Zeng, X.

2004-12-01

217

Lithium Metal Anodes for Rechargeable Batteries  

SciTech Connect

Rechargeable lithium metal batteries have much higher energy density than those of lithium ion batteries using graphite anode. Unfortunately, uncontrollable dendritic lithium growth inherent in these batteries (upon repeated charge/discharge cycling) and limited Coulombic efficiency during lithium deposition/striping has prevented their practical application over the past 40 years. With the emerging of post Li-ion batteries, safe and efficient operation of lithium metal anode has become an enabling technology which may determine the fate of several promising candidates for the next generation of energy storage systems, including rechargeable Li-air battery, Li-S battery, and Li metal battery which utilize lithium intercalation compounds as cathode. In this work, various factors which affect the morphology and Coulombic efficiency of lithium anode will be analyzed. Technologies used to characterize the morphology of lithium deposition and the results obtained by modeling of lithium dendrite growth will also be reviewed. At last, recent development in this filed and urgent need in this field will also be discussed.

Xu, Wu; Wang, Jiulin; Ding, Fei; Chen, Xilin; Nasybulin, Eduard N.; Zhang, Yaohui; Zhang, Jiguang

2014-02-28

218

Comparing groundwater recharge and storage variability from GRACE satellite observations with observed water levels and recharge model simulations  

NASA Astrophysics Data System (ADS)

Sustainable management of groundwater resources, particularly in water stressed regions, requires estimates of groundwater recharge. This study in southern Mali, Africa compares approaches for estimating groundwater recharge and understanding recharge processes using a variety of methods encompassing groundwater level-climate data analysis, GRACE satellite data analysis, and recharge modelling for current and future climate conditions. Time series data for GRACE (2002-2006) and observed groundwater level data (1982-2001) do not overlap. To overcome this problem, GRACE time series data were appended to the observed historical time series data, and the records compared. Terrestrial water storage anomalies from GRACE were corrected for soil moisture (SM) using the Global Land Data Assimilation System (GLDAS) to obtain monthly groundwater storage anomalies (GRACE-SM), and monthly recharge estimates. Historical groundwater storage anomalies and recharge were determined using the water table fluctuation method using observation data from 15 wells. Historical annual recharge averaged 145.0 mm (or 15.9% of annual rainfall) and compared favourably with the GRACE-SM estimate of 149.7 mm (or 14.8% of annual rainfall). Both records show lows and peaks in May and September, respectively; however, the peak for the GRACE-SM data is shifted later in the year to November, suggesting that the GLDAS may poorly predict the timing of soil water storage in this region. Recharge simulation results show good agreement between the timing and magnitude of the mean monthly simulated recharge and the regional mean monthly storage anomaly hydrograph generated from all monitoring wells. Under future climate conditions, annual recharge is projected to decrease by 8% for areas with luvisols and by 11% for areas with nitosols. Given this potential reduction in groundwater recharge, there may be added stress placed on an already stressed resource.

Allen, D. M.; Henry, C.; Demon, H.; Kirste, D. M.; Huang, J.

2011-12-01

219

Melt-Formable Block Copolymer Electrolytes for Lithium Rechargeable Batteries  

E-print Network

Melt-Formable Block Copolymer Electrolytes for Lithium Rechargeable Batteries Anne-Vale´rie G conductivity in polymer electrolytes for solid-state rechargeable lithium batteries. However, due to the strong. Herein, we report the design of new block copolymer electrolytes based on poly methyl methacrylate , PMMA

Sadoway, Donald Robert

220

Investigation of Possible Extra ~Recharge During Pumping in Nottinghant .Aquifer  

E-print Network

Investigation of Possible Extra ~Recharge During Pumping in Nottinghant .Aquifer by Jiu J. Jiaoa Abstract Approaches to investigate possible recharge during a pumping test period are demonstrated by analyzing the pumping test data from the Nottingham aquifer, UK. The pumping lasted more than 200 days

Jiao, Jiu Jimmy

221

Estimation of groundwater recharge and discharge across northern Australia  

Microsoft Academic Search

Groundwater recharge is one of the more difficult components of the hydrological cycle to estimate but one that is becoming increasingly important as Australia turns to groundwater resources for future economic development. Also of concern is groundwater discharge. The extraction of groundwater by pumping inevitably reduces groundwater discharge to rivers where the two are connected. Knowledge of both groundwater recharge

Russell S. Crosbie; James L. McCallum; Glenn A. Harrington

2009-01-01

222

Autonomous Battery Recharging for Indoor Mobile Robots Seungjun Oh  

E-print Network

1 Autonomous Battery Recharging for Indoor Mobile Robots Seungjun Oh Australian National University the batteries on a mobile robot. The robot used in this project is the Nomadic Technologies? Nomad XR4000 mobile robot. The battery recharging system was implemented using the robot's built-in sensors to control

223

Sensitivity and uncertainty analysis of the recharge boundary condition  

Microsoft Academic Search

The reliability analysis method is integrated with MODFLOW to study the impact of recharge on the groundwater flow system at a study area in New Jersey. The performance function is formulated in terms of head or flow rate at a pumping well, while the recharge sensitivity vector is computed efficiently by implementing the adjoint method in MODFLOW. The developed methodology

M. I. Jyrkama; J. F. Sykes

2006-01-01

224

Global synthesis of groundwater recharge in semiarid and arid regions  

USGS Publications Warehouse

Global synthesis of the findings from ???140 recharge study areas in semiarid and arid regions provides important information on recharge rates, controls, and processes, which are critical for sustainable water development. Water resource evaluation, dryland salinity assessment (Australia), and radioactive waste disposal (US) are among the primary goals of many of these recharge studies. The chloride mass balance (CMB) technique is widely used to estimate recharge. Average recharge rates estimated over large areas (40-374000 km2) range from 0.2 to 35 mm year-1, representing 0.1-5% of long-term average annual precipitation. Extreme local variability in recharge, with rates up to ???720 m year-1, results from focussed recharge beneath ephemeral streams and lakes and preferential flow mostly in fractured systems. System response to climate variability and land use/land cover (LU/LC) changes is archived in unsaturated zone tracer profiles and in groundwater level fluctuations. Inter-annual climate variability related to El Nin??o Southern Oscillation (ENSO) results in up to three times higher recharge in regions within the SW US during periods of frequent El Nin??os (1977-1998) relative to periods dominated by La Nin??as (1941-1957). Enhanced recharge related to ENSO is also documented in Argentina. Climate variability at decadal to century scales recorded in chloride profiles in Africa results in recharge rates of 30 mm year-1 during the Sahel drought (1970-1986) to 150 mm year-1 during non-drought periods. Variations in climate at millennial scales in the SW US changed systems from recharge during the Pleistocene glacial period (??? 10 000 years ago) to discharge during the Holocene semiarid period. LU/LC changes such as deforestation in Australia increased recharge up to about 2 orders of magnitude. Changes from natural grassland and shrublands to dryland (rain-fed) agriculture altered systems from discharge (evapotranspiration, ET) to recharge in the SW US. The impact of LU change was much greater than climate variability in Niger (Africa), where replacement of savanna by crops increased recharge by about an order of magnitude even during severe droughts. Sensitivity of recharge to LU/LC changes suggests that recharge may be controlled through management of LU. In irrigated areas, recharge varies from 10 to 485 mm year-1, representing 1-25% of irrigation plus precipitation. However, irrigation pumpage in groundwater-fed irrigated areas greatly exceeds recharge rates, resulting in groundwater mining. Increased recharge related to cultivation has mobilized salts that accumulated in the unsaturated zone over millennia, resulting in widespread groundwater and surface water contamination, particularly in Australia. The synthesis of recharge rates provided in this study contains valuable information for developing sustainable groundwater resource programmes within the context of climate variability and LU/LC change. Copyright ?? 2006 John Wiley & Sons, Ltd.

Scanlon, B.R.; Keese, K.E.; Flint, A.L.; Flint, L.E.; Gaye, C.B.; Edmunds, W.M.; Simmers, I.

2006-01-01

225

Global synthesis of groundwater recharge in semiarid and arid regions  

NASA Astrophysics Data System (ADS)

Global synthesis of the findings from 140 recharge study areas in semiarid and arid regions provides important information on recharge rates, controls, and processes, which are critical for sustainable water development. Water resource evaluation, dryland salinity assessment (Australia), and radioactive waste disposal (US) are among the primary goals of many of these recharge studies. The chloride mass balance (CMB) technique is widely used to estimate recharge. Average recharge rates estimated over large areas (40-374 000 km2) range from 0.2 to 35 mm year-1, representing 0.1-5% of long-term average annual precipitation. Extreme local variability in recharge, with rates up to 720 m year-1, results from focussed recharge beneath ephemeral streams and lakes and preferential flow mostly in fractured systems. System response to climate variability and land use/land cover (LU/LC) changes is archived in unsaturated zone tracer profiles and in groundwater level fluctuations. Inter-annual climate variability related to El Niño Southern Oscillation (ENSO) results in up to three times higher recharge in regions within the SW US during periods of frequent El Niños (1977-1998) relative to periods dominated by La Niñas (1941-1957). Enhanced recharge related to ENSO is also documented in Argentina. Climate variability at decadal to century scales recorded in chloride profiles in Africa results in recharge rates of 30 mm year-1 during the Sahel drought (1970-1986) to 150 mm year-1 during non-drought periods. Variations in climate at millennial scales in the SW US changed systems from recharge during the Pleistocene glacial period (10 000 years ago) to discharge during the Holocene semiarid period. LU/LC changes such as deforestation in Australia increased recharge up to about 2 orders of magnitude. Changes from natural grassland and shrublands to dryland (rain-fed) agriculture altered systems from discharge (evapotranspiration, ET) to recharge in the SW US. The impact of LU change was much greater than climate variability in Niger (Africa), where replacement of savanna by crops increased recharge by about an order of magnitude even during severe droughts. Sensitivity of recharge to LU/LC changes suggests that recharge may be controlled through management of LU. In irrigated areas, recharge varies from 10 to 485 mm year-1, representing 1-25% of irrigation plus precipitation. However, irrigation pumpage in groundwater-fed irrigated areas greatly exceeds recharge rates, resulting in groundwater mining. Increased recharge related to cultivation has mobilized salts that accumulated in the unsaturated zone over millennia, resulting in widespread groundwater and surface water contamination, particularly in Australia. The synthesis of recharge rates provided in this study contains valuable information for developing sustainable groundwater resource programmes within the context of climate variability and LU/LC change.

Scanlon, Bridget R.; Keese, Kelley E.; Flint, Alan L.; Flint, Lorraine E.; Gaye, Cheikh B.; Edmunds, W. Michael; Simmers, Ian

2006-10-01

226

Lithium electronic environments in rechargeable battery electrodes  

NASA Astrophysics Data System (ADS)

This work investigates the electronic environments of lithium in the electrodes of rechargeable batteries. The use of electron energy-loss spectroscopy (EELS) in conjunction with transmission electron microscopy (TEM) is a novel approach, which when coupled with conventional electrochemical experiments, yield a thorough picture of the electrode interior. Relatively few EELS experiments have been preformed on lithium compounds owing to their reactivity. Experimental techniques were established to minimize sample contamination and control electron beam damage to studied compounds. Lithium hydroxide was found to be the most common product of beam damaged lithium alloys. Under an intense electron beam, halogen atoms desorbed by radiolysis in lithium halides. EELS spectra from a number of standard lithium compounds were obtained in order to identify the variety of spectra encountered in lithium rechargeable battery electrodes. Lithium alloys all displayed characteristically broad Li K-edge spectra, consistent with transitions to continuum states. Transitions to bound states were observed in the Li K and oxygen K-edge spectra of lithium oxides. Lithium halides were distinguished by their systematic chemical shift proportional to the anion electronegativity. Good agreement was found with measured lithium halide spectra and electron structure calculations using a self-consistant multiscattering code. The specific electrode environments of LiC6, LiCoO2, and Li-SnO were investigated. Contrary to published XPS predictions, lithium in intercalated graphite was determined to be in more metallic than ionic. We present the first experimental evidence of charge compensation by oxygen ions in deintercalated LiCoO2. Mossbauer studies on cycled Li-SnO reveal severely defective structures on an atomic scale. Metal hydride systems are presented in the appendices of this thesis. The mechanical alloying of immiscible Fe and Mg powders resulted in single-phase bcc alloys of less than 20 at% Mg. Kinetic studies on LaNi5-xSn x alloys proved that the mass transfer of hydrogen through these alloys was not hindered with increasing Sn substitutions for Ni. Collaborations with Energizer(c) found LanNi4.7Sn0.3 alloys to possess limited utility in rechargeable nickel-metal-hydride sealed-cell batteries.

Hightower, Adrian

227

Artificial Recharge Coupled with Flood Mitigation in Jeju, Korea  

NASA Astrophysics Data System (ADS)

The primary goal of this study is to develop and apply the artificial recharge system at Han Stream in Jeju Island, Korea, for not only securing sustainable groundwater resources, but also mitigating severe floods occurred due to the global climate changes. Jeju-friendly Aquifer Recharge Technology (J-ART) in this study has been developed by capturing ephemeral stream water with no interference in the environments such as natural recharge or eco-system, storing the flood water in the reservoirs, recharging it through designed borehole after appropriate water treatment, and then making it to be used at down-gradient production wells. For optimal design of J-ART, we conducted injection tests at the monitoring well (MW5) as well as at the planned recharge site during drilling the recharge wells and performed a modeling with the data obtained. Based on the modeling results, the artificial recharge wells were developed with a design of 10-meter spacing between the wells and 35-40 meter depths, which has a capacity of more than 2,500,000 m3 of groundwater resources in a year. Characterizing groundwater flow from recharge area to discharge area should be achieved to assess the efficiency of J-ART. The resistivity logging employed to predict water flow in unsaturated zone during artificial recharge based on the inverse modeling and resistivity change patterns. Stable isotope studies of deuterium and oxygen-18 of surface waters and groundwaters were carried out to interpret mixing and flow in groundwaters impacted by artificial recharge. Transient models were developed to predict the effects of artificial recharge using the hydraulic properties of aquifers, groundwater levels, and meteorological data. Time series changes of water balance after artificial recharge were analyzed, and residence time of the recharged water was also predicted with a certain degree of uncertainty. Keywords: J-ART, Hydrogeological methods, Geophysical survey, Stable isotopes, Groundwater modeling, Jeju Island. Acknowledgements: This research was supported by a grant (code 3-2-3) from the Sustainable Water Resources Research Center of 21st Century Frontier Research Program.

Kim, Y.; Koo, M.; Lee, K.; Moon, D.; Barry, J. M.; Park, W.

2010-12-01

228

Climate variability effects on urban recharge beneath low impact development  

NASA Astrophysics Data System (ADS)

Groundwater resources in urban and coastal environments are highly vulnerable to human pressures and climate variability and change, and many communities face water shortages and need to find alternative water supplies. Therefore, understanding how low impact development (LID) site planning and integrated/best management practices (BMPs) affect recharge rates and volumes is important because of the increasing use of LID and BMP to reduce stormwater runoff and improve surface-water quality. Often considered a secondary management benefit, many BMPs may also enhance recharge to local aquifers; however these hypothesized benefits have not been thoroughly tested or quantified. In this study, we quantify stormwater capture and recharge enhancement beneath a BMP infiltration trench of the LID research network at San Francisco State University, San Francisco, California. Stormwater capture and retention was analyzed using the SCS TR-55 curve number method and in-situ infiltration rates to assess LID storage. Recharge was quantified using vadose zone monitoring equipment, a detailed water budget analysis, and a Hydrus-2D model. Additionally, the effects of historical and predicted future precipitation on recharge rates were examined using precipitation from the Geophysical Fluid Dynamic Laboratory (GFDL) A1F1 climate scenario. Observed recharge rates beneath the infiltration trench range from 1,600 to 3,700 mm/year and are an order of magnitude greater than recharge beneath an irrigated grass lawn and a natural setting. The Hydrus-2D model results indicate increased recharge under the GFDL A1F1 scenario compared with historical and GFDL modeled 20th century rates because of the higher frequency of large precipitation events that induce runoff into the infiltration trench. However, under a simulated A1F1 El Niño year, recharge calculated by a water budget does not increase compared with current El Niño recharge rates. In comparison, simulated recharge rates were considerably lower beneath the grass lawn for historical and future precipitation years. This work highlights the potential management strategy of using LID to capture excess runoff during El Niño years that can be recharged and stored as groundwater. An additional benefit of LID in coastal aquifer systems is the ability to capture and redirect precipitation from runoff to recharge that may help mitigate the negative effects from groundwater pumping and sea-water intrusion.

Newcomer, M. E.; Gurdak, J. J.

2012-12-01

229

Rechargeable metal hydrides for spacecraft application  

NASA Technical Reports Server (NTRS)

Storing hydrogen on board the Space Station presents both safety and logistics problems. Conventional storage using pressurized bottles requires large masses, pressures, and volumes to handle the hydrogen to be used in experiments in the U.S. Laboratory Module and residual hydrogen generated by the ECLSS. Rechargeable metal hydrides may be competitive with conventional storage techniques. The basic theory of hydride behavior is presented and the engineering properties of LaNi5 are discussed to gain a clear understanding of the potential of metal hydrides for handling spacecraft hydrogen resources. Applications to Space Station and the safety of metal hydrides are presented and compared to conventional hydride storage. This comparison indicates that metal hydrides may be safer and require lower pressures, less volume, and less mass to store an equivalent mass of hydrogen.

Perry, J. L.

1988-01-01

230

Advanced rechargeable sodium batteries with novel cathodes  

NASA Astrophysics Data System (ADS)

Various high energy density rechargeable batteries are being considered for future space applications. Of these, the sodium sulfur battery is one of the leading candidates. The primary advantage is the high energy density (760 Wh/kg theoretical). Energy densities in excess of 180 Wh/kg have been realized in practical batteries. More recently, cathodes other than sulfur are being evaluated. Researchers at JPL are evaluating various new cathode materials for use in high energy density sodium batteries for advanced space applications. The approach is to carry out basic electrochemical studies of these materials in a sodium cell configuration in order to understand their fundamental behaviors. Thus far studies have focused on alternate metal chlorides such as CuCl2 and organic cathode materials such as tetracyanoethylene (TCNE).

Distefano, S.; Ratnakumar, B. V.; Bankston, C. P.

1989-12-01

231

Advanced rechargeable sodium batteries with novel cathodes  

NASA Astrophysics Data System (ADS)

Various high energy density rechargeable batteries are being considered for future space applications. Of these, the sodium-sulfur battery is one of the leading candidates. The primary advantage is the high energy density (760 W h kg -1 theoretical). Energy densities in excess of 180 W h kg -1 have been realized in practical batteries. More recently, cathodes other than sulfur are being evaluated. We, at JPL, are evaluating various new cathode materials for use in high energy density sodium batteries for advanced space applications. Our approach is to carry out basic electrochemical studies of these materials in a sodium cell configuration in order to understand their fundamental behaviors. Thus far, our studies have focussed on alternative metal chlorides such as CuCl 2 and organic cathode materials such as TCNE.

Di Stefano, S.; Ratnakumar, B. V.; Bankston, C. P.

232

Polymer Energy Rechargeable System Battery Being Developed  

NASA Technical Reports Server (NTRS)

Long description. Illustrations of discotic liquid crystals, rod-coil polymers, lithium-ion conducting channel dilithium phthalocyanine (Li2Pc) from top and side, novel star polyethylene oxide structures, composite polyethylene oxide materials (showing polyethylene oxide + lithium salt, carbon atoms and oxygen atoms), homopolyrotaxanes, and diblock copolymers In fiscal year 2000, NASA established a program to develop the next generation, lithium-based, polymer electrolyte batteries for aerospace applications. The goal of this program, known as Polymer Energy Rechargeable Systems (PERS), is to develop a space-qualified, advanced battery system embodying polymer electrolyte and lithium-based electrode technologies and to establish world-class domestic manufacturing capabilities for advanced batteries with improved performance characteristics that address NASA s future aerospace battery requirements.

Manzo, Michelle A.

2003-01-01

233

A model recharge system for the LCC  

SciTech Connect

This report describes a model recharge system for LCC. The model is based on the premise that the charges assessed should accurately reflect the actual cost to the LCC for the resources being used. The benefits of such a system include a sense of absolute fairness to all users, plus incentives to conserve scarce resources. In developing this model it has been necessary to make compromises between conflicting objectives - such as making the model complete and comprehensive while keeping it simple and manageable. When compromises have been made, a brief discussion of the rationale behind each compromise has been included. It is quite possible that additional compromises will have to be made as the model moves toward implementation.

Carlson, R.E.; Hogan, C.B.

1988-05-05

234

Advanced rechargeable sodium batteries with novel cathodes  

NASA Technical Reports Server (NTRS)

Various high energy density rechargeable batteries are being considered for future space applications. Of these, the sodium-sulfur battery is one of the leading candidates. The primary advantage is the high energy density (760 W h/kg theoretical). Energy densities in excess of 180 W h/kg have been realized in practical batteries. More recently, cathodes other than sulfur are being evaluated. Various new cathode materials are presently being evaluated for use in high energy density sodium batteries for advanced space applications. The approach is to carry out basic electrochemical studies of these materials in a sodium cell configuration in order to understand their fundamental behaviors. Thus far, the studies have focussed on alternative metal chlorides such as CuCl2 and organic cathode materials such as TCNE.

Di Stefano, S.; Ratnakumar, B. V.; Bankston, C. P.

1990-01-01

235

Advanced rechargeable sodium batteries with novel cathodes  

NASA Technical Reports Server (NTRS)

Various high energy density rechargeable batteries are being considered for future space applications. Of these, the sodium sulfur battery is one of the leading candidates. The primary advantage is the high energy density (760 Wh/kg theoretical). Energy densities in excess of 180 Wh/kg have been realized in practical batteries. More recently, cathodes other than sulfur are being evaluated. Researchers at JPL are evaluating various new cathode materials for use in high energy density sodium batteries for advanced space applications. The approach is to carry out basic electrochemical studies of these materials in a sodium cell configuration in order to understand their fundamental behaviors. Thus far studies have focused on alternate metal chlorides such as CuCl2 and organic cathode materials such as tetracyanoethylene (TCNE).

Distefano, S.; Ratnakumar, B. V.; Bankston, C. P.

1989-01-01

236

Oxygen electrodes for rechargeable alkaline fuel cells  

NASA Technical Reports Server (NTRS)

Electrocatalysts and supports for the positive electrode of moderate temperature single unit rechargeable alkaline fuel cells were investigated and developed. The electrocatalysts are defined as the material with a higher activity for the oxygen electrode reaction than the support. Advanced development will require that the materials be prepared in high surface area forms, and may also entail integration of various candidate materials. Eight candidate support materials and seven electrocatalysts were investigated. Of the 8 support, 3 materials meet the preliminary requirements in terms of electrical conductivity and stability. Emphasis is now on preparing in high surface area form and testing under more severe corrosion stress conditions. Of the 7 electrocatalysts prepared and evaluated, at least 5 materials remain as potential candidates. The major emphasis remains on preparation, physical characterization and electrochemical performance testing.

Swette, Larry; Giner, Jose

1987-01-01

237

Polymer Energy Rechargeable System (PERS) Development Program  

NASA Technical Reports Server (NTRS)

The National Aeronautics and Space Administration (NASA) and the Air Force Research Laboratory (AFRL) have recently established a collaborative effort to support the development of polymer-based, lithium-based cell chemistries and battery technologies to address the next generation of aerospace applications and mission needs. The overall objective of this development program, which is referred to as PERS, Polymer Energy Rechargeable System, is to establish a world-class technology capability and U.S. leadership in polymer-based battery technology for aerospace applications. Programmatically, the PERS initiative will exploit both interagency collaborations to address common technology and engineering issues and the active participation of academia and private industry. The initial program phases will focus on R&D activities to address the critical technical issues and challenges at the cell level.

Baldwin, Richard S.; Manzo, Michelle A.; Dalton, Penni J.; Marsh, Richard A.; Surampudi, Rao

2001-01-01

238

Quantifying potential recharge in mantled sinkholes using ERT.  

PubMed

Potential recharge through thick soils in mantled sinkholes was quantified using differential electrical resistivity tomography (ERT). Conversion of time series two-dimensional (2D) ERT profiles into 2D volumetric water content profiles using a numerically optimized form of Archie's law allowed us to monitor temporal changes in water content in soil profiles up to 9 m in depth. Combining Penman-Monteith daily potential evapotranspiration (PET) and daily precipitation data with potential recharge calculations for three sinkhole transects indicates that potential recharge occurred only during brief intervals over the study period and ranged from 19% to 31% of cumulative precipitation. Spatial analysis of ERT-derived water content showed that infiltration occurred both on sinkhole flanks and in sinkhole bottoms. Results also demonstrate that mantled sinkholes can act as regions of both rapid and slow recharge. Rapid recharge is likely the result of flow through macropores (such as root casts and thin gravel layers), while slow recharge is the result of unsaturated flow through fine-grained sediments. In addition to developing a new method for quantifying potential recharge at the field scale in unsaturated conditions, we show that mantled sinkholes are an important component of storage in a karst system. PMID:18823398

Schwartz, Benjamin F; Schreiber, Madeline E

2009-01-01

239

[Effects of reclaimed water recharge on groundwater quality: a review].  

PubMed

Reclaimed water recharge to groundwater is an effective way to relieve water resource crisis. However, reclaimed water contains some pollutants such as nitrate, heavy metals, and new type contaminants, and thus, there exists definite environmental risk in the reclaimed water recharge to groundwater. To promote the development of reclaimed water recharge to groundwater and the safe use of reclaimed water in China, this paper analyzed the relevant literatures and practical experiences around the world, and summarized the effects of different reclaimed water recharge modes on the groundwater quality. Surface recharge makes the salt and nitrate contents in groundwater increased but the risk of heavy metals pollution be smaller, whereas well recharge can induce the arsenic release from sedimentary aquifers, which needs to be paid more attention to. New type contaminants are the hotspots in current researches, and their real risks are unknown. Pathogens have less pollution risks on groundwater, but some virus with strong activity can have the risks. Some suggestions were put forward to reduce the risks associated with the reclaimed water recharge to groundwater in China. PMID:24015541

Chen, Wei-Ping; Lü, Si-Dan; Wang, Mei-E; Jiao, Wen-Tao

2013-05-01

240

Echo Meadows Project Winter Artificial Recharge.  

SciTech Connect

This report discusses the findings of the Echo Meadows Project (BPA Project 2001-015-00). The main purpose of this project is to artificially recharge an alluvial aquifer, WITH water from Umatilla River during the winter high flow period. In turn, this recharged aquifer will discharge an increased flow of cool groundwater back to the river, thereby improving Umatilla River water quality and temperature. A considerable side benefit is that the Umatilla River should improve as a habitat for migration, spanning, and rearing of anadromous and resident fish. The scope of this project is to provide critical baseline information about the Echo Meadows and the associated reach of the Umatilla River. Key elements of information that has been gathered include: (1) Annual and seasonal groundwater levels in the aquifer with an emphasis on the irrigation season, (2) Groundwater hydraulic properties, particularly hydraulic conductivity and specific yield, and (3) Groundwater and Umatilla River water quality including temperature, nutrients and other indicator parameters. One of the major purposes of this data gathering was to develop input to a groundwater model of the area. The purpose of the model is to estimate our ability to recharge this aquifer using water that is only available outside of the irrigation season (December through the end of February) and to estimate the timing of groundwater return flow back to the river. We have found through the data collection and modeling efforts that this reach of the river had historically returned as much as 45 cubic feet per second (cfs) of water to the Umatilla River during the summer and early fall. However, this return flow was reduced to as low as 10 cfs primarily due to reduced quantities of irrigation application, gain in irrigation efficiencies and increased groundwater pumping. Our modeling indicated that it is possible to restore these critical return flows using applied water outside of the irrigation season. We further found that this water can be timed to return to the river during the desired time of the year (summer to early fall). This is because the river stage, which remains relatively high until this time, drops during the irrigation season-thereby releasing the stored groundwater and increasing river flows. A significant side benefit is that these enhanced groundwater return flows will be clean and cold, particularly as compared to the Umatilla River. We also believe that this same type of application of water could be done and the resulting stream flows could be realized in other watersheds throughout the Pacific Northwest. This means that it is critical to compare the results from this baseline report to the full implementation of the project in the next phase. As previously stated, this report only discusses the results of data gathered during the baseline phase of this project. We have attempted to make the data that has been gathered accessible with the enclosed databases and spreadsheets. We provide computer links in this report to the databases so that interested parties can fully evaluate the data that has been gathered. However, we cannot emphasize too strongly that the real value of this project is to implement the phases to come, compare the results of these future phases to this baseline and develop the science and strategies to successfully implement this concept to other rivers in the Pacific Northwest. The results from our verified and calibrated groundwater model matches the observed groundwater data and trends collected during the baseline phase. The modeling results indicate that the return flows may increase to their historic values with the addition of 1 acre-ft/acre of recharge water to the groundwater system (about 9,600 acre-feet total). What this means is that through continued recharge project, you can double to quadruple the annual baseflow of the Umatilla River during the low summer and fall flow periods as compared to the present base-flow. The cool and high quality recharge water is a significant beneficial impact to the river system.

Ziari, Fred

2002-12-19

241

Effects of artificial recharge on the Ogallala aquifer, Texas  

USGS Publications Warehouse

Four recharge tests were conducted by injecting water from playa lakes through wells into the Ogallala Formation. Injection was by gravity flow and by pumping under pressure. At one site, 34-acre feet of water was injected by gravity and produced a significant increase in yield of the well. At a second site, gravity injection of only 0.58 acre-foot caused a significant decrease in permeability due to plugging by suspended sediment. At two other sites, injection by pumping 6 and 14 acre-feet respectively, resulted in discharge of water at the surface and in perching of water above the water table. Differences in success of recharge were largely due to aquifer lithology and, therefore, the type of permeability; the concentration of suspended solids in the recharge water; and the injection technique. The injection technique can be controlled and the concentration of suspended solids can be minimized by treatment, but the site for well recharge will accept water most rapidly if it is selected on the basis of a favorable geohydrologic environment. Geophysical logs were used to study the effect of aquifer lithology on recharge and to understand the movement of injected water. Temperature logs were particularly useful in tracing the movement of recharged water. Natural-gamma, gamma-gamma, and neutron logs provided important data on lithology and porosity in the aquifer and changes in porosity and water distribution resulting from recharge. Effective recharge of the Ogallala Formation, using water from playa lakes, is possible where geohydrologic conditions are favorable and the recharge system is properly constructed.

Brown, Richmond Flint; Keys, W.S.

1985-01-01

242

Ground-water recharge from streamflow data, NW Florida  

USGS Publications Warehouse

Annual base flows of streams draining Okaloosa County and adjacent areas in northwest Florida were determined through hydrograph separation and correlation techniques for purposes of evaluating variations in ground-water recharge rates. Base flows were least in the northern part of the county and greatest in the southern part. Topographic and soils data were then superimposed on the distribution of base flow by subbasin to produce a map showing distribution of ground-water recharge throughout the county. The highest recharge rate occurs in the southern part of the county where relatively flat upland areas underlain by excessively drained sandy soils result in minimal storm runoff and evapotranspiration.

Vecchioli, John; Bridges, W.C.; Rumenik, R.P.; Grubbs, J.W.

1991-01-01

243

Recharge and discharge calculations to characterize the groundwater hydrologic balance  

SciTech Connect

Several methods are presented to quantify the ground water component of the hydrologic balance; including (1) hydrograph separation techniques, (2) water budget calculations, (3) spoil discharge techniques, and (4) underground mine inflow studies. Stream hydrograph analysis was used to calculate natural groundwater recharge and discharge rates. Yearly continuous discharge hydrographs were obtained for 16 watersheds in the Cumberland Plateau area of Tennessee. Baseflow was separated from storm runoff using computerized hydrograph analysis techniques developed by the USGS. The programs RECESS, RORA, and PART were used to develop master recession curves, calculate ground water recharge, and ground water discharge respectively. Station records ranged from 1 year of data to 60 years of data with areas of 0.67 to 402 square miles. Calculated recharge ranged from 7 to 28 inches of precipitation while ground water discharge ranged from 6 to 25 inches. Baseflow ranged from 36 to 69% of total flow. For sites with more than 4 years of data the median recharge was 20 inches/year and the 95% confidence interval for the median was 16.4 to 23.8 inches of recharge. Water budget calculations were also developed independently by a mining company in southern Tennessee. Results showed about 19 inches of recharge is available on a yearly basis. A third method used spoil water discharge measurements to calculate average recharge rate to the mine. Results showed 21.5 inches of recharge for this relatively flat area strip mine. In a further analysis it was shown that premining soil recharge rates of 19 inches consisted of about 17 inches of interflow and 2 inches of deep aquifer recharge while postmining recharge to the spoils had almost no interflow component. OSM also evaluated underground mine inflow data from northeast Tennessee and southeast Kentucky. This empirical data showed from 0.38 to 1.26 gallons per minute discharge per unit acreage of underground workings. This is the equivalent to 7 to 24 inches of recharge per year. The four methods provide a good comparative way to quantify the groundwater portion of the hydrologic balance.

Liddle, R.G. [Dept. of the Interior, Knoxville, TN (United States). Office of Surface Mining

1998-12-31

244

Geophysical expression of natural recharge in different geological terrains.  

PubMed

Behavior of the Dar-Zarrouk parameters--longitudinal unit conductance, transverse unit resistance, longitudinal resistivity, and transverse resistivity--has been compared with the behavior of the natural recharge in two geological terrains. Contour patterns of the geophysical parameters and those of natural recharge have been analyzed and a qualitative relation in their behavior was recognized. Graphical comparison of the geophysical and hydrogeological parameters clearly illustrates a qualitative relationship between the two parameters. Use of such qualitative relation in the field of ground water exploration and management studies is explained. A modest beginning is attempted to arrive at a quantitative relation between natural recharge and Dar-Zarrouk parameters. PMID:14649869

Hodlur, G K; Singh, U K; Das, R K; Rangarajan, R; Chand, Ramesh; Singh, S B

2003-01-01

245

Layer cathode methods of manufacturing and materials for Li-ion rechargeable batteries  

DOEpatents

A positive electrode active material for lithium-ion rechargeable batteries of general formula Li.sub.1+xNi.sub..alpha.Mn.sub..beta.A.sub..gamma.O.sub.2 and further wherein A is Mg, Zn, Al, Co, Ga, B, Zr, or Ti and 0aqueous solution method or a sol-gel method which is followed by a rapid quenching from high temperatures into liquid nitrogen or liquid helium.

Kang, Sun-Ho (Naperville, IL); Amine, Khalil (Downers Grove, IL)

2008-01-01

246

Biologically derived melanin electrodes in aqueous sodium-ion energy storage devices  

PubMed Central

Biodegradable electronics represents an attractive and emerging paradigm in medical devices by harnessing simultaneous advantages afforded by electronically active systems and obviating issues with chronic implants. Integrating practical energy sources that are compatible with the envisioned operation of transient devices is an unmet challenge for biodegradable electronics. Although high-performance energy storage systems offer a feasible solution, toxic materials and electrolytes present regulatory hurdles for use in temporary medical devices. Aqueous sodium-ion charge storage devices combined with biocompatible electrodes are ideal components to power next-generation biodegradable electronics. Here, we report the use of biologically derived organic electrodes composed of melanin pigments for use in energy storage devices. Melanins of natural (derived from Sepia officinalis) and synthetic origin are evaluated as anode materials in aqueous sodium-ion storage devices. Na+-loaded melanin anodes exhibit specific capacities of 30.4 ± 1.6 mAhg?1. Full cells composed of natural melanin anodes and ?-MnO2 cathodes exhibit an initial potential of 1.03 ± 0.06 V with a maximum specific capacity of 16.1 ± 0.8 mAhg?1. Natural melanin anodes exhibit higher specific capacities compared with synthetic melanins due to a combination of beneficial chemical, electrical, and physical properties exhibited by the former. Taken together, these results suggest that melanin pigments may serve as a naturally occurring biologically derived charge storage material to power certain types of medical devices. PMID:24324163

Kim, Young Jo; Wu, Wei; Chun, Sang-Eun; Whitacre, Jay F.; Bettinger, Christopher J.

2013-01-01

247

Flow of Aqueous Humor  

MedlinePLUS

... Involved Research Grants Special Events Flow of Aqueous Humor © 2000 BrightFocus Foundation Unauthorized reprints not allowed. Most , ... remains normal when some of the fluid (aqueous humor) produced by the eye's ciliary body flows out ...

248

Understanding the role of manganese dioxide in the oxidation of phenolic compounds by aqueous permanganate.  

PubMed

Recent studies have shown that manganese dioxide (MnO2) can significantly accelerate the oxidation kinetics of phenolic compounds such as triclosan and chlorophenols by potassium permanganate (Mn(VII)) in slightly acidic solutions. However, the role of MnO2 (i.e., as an oxidant vs catalyst) is still unclear. In this work, it was demonstrated that Mn(VII) oxidized triclosan (i.e., trichloro-2-phenoxyphenol) and its analogue 2-phenoxyphenol, mainly generating ether bond cleavage products (i.e., 2,4-dichlorophenol and phenol, respectively), while MnO2 reacted with them producing appreciable dimers as well as hydroxylated and quinone-like products. Using these two phenoxyphenols as mechanistic probes, it was interestingly found that MnO2 formed in situ or prepared ex situ greatly accelerated the kinetics but negligibly affected the pathways of their oxidation by Mn(VII) at acidic pH 5. The yields (R) of indicative products 2,4-dichlorophenol and phenol from their respective probes (i.e., molar ratios of product formed to probe lost) under various experimental conditions were quantified. Comparable R values were obtained during the treatment by Mn(VII) in the absence vs presence of MnO2. Meanwhile, it was confirmed that MnO2 could accelerate the kinetics of Mn(VII) oxidation of refractory nitrophenols (i.e., 2-nitrophenol and 4-nitrophenol), which otherwise showed negligible reactivity toward Mn(VII) and MnO2 individually, and the effect of MnO2 was strongly dependent upon its concentration as well as solution pH. These results clearly rule out the role of MnO2 as a mild co-oxidant and suggest a potential catalytic effect on Mn(VII) oxidation of phenolic compounds regardless of their susceptibility to oxidation by MnO2. PMID:25437924

Jiang, Jin; Gao, Yuan; Pang, Su-Yan; Lu, Xue-Ting; Zhou, Yang; Ma, Jun; Wang, Qiang

2015-01-01

249

Bipolar rechargeable lithium battery for high power applications  

NASA Technical Reports Server (NTRS)

Viewgraphs of a discussion on bipolar rechargeable lithium battery for high power applications are presented. Topics covered include cell chemistry, electrolytes, reaction mechanisms, cycling behavior, cycle life, and cell assembly.

Hossain, Sohrab; Kozlowski, G.; Goebel, F.

1993-01-01

250

GROUNDWATER RECHARGE/DISCHARGE, NEUSE RIVER WATERSHED, NC  

EPA Science Inventory

The North Carolina Department of Environment and Natural Resources, Division of Water Quality and Groundwater Section, in cooperation with the NC Center for Geographic Information and Analysis, developed the Groundwater Recharge/Discharge digital data to enhance planning, siting ...

251

ENGINEERING ECONOMIC ANALYSIS OF A PROGRAM FOR ARTIFICIAL GROUNDWATER RECHARGE.  

USGS Publications Warehouse

This study describes and demonstrates two alternate methods for evaluating the relative costs and benefits of artificial groundwater recharge using percolation ponds. The first analysis considers the benefits to be the reduction of pumping lifts and land subsidence; the second considers benefits as the alternative costs of a comparable surface delivery system. Example computations are carried out for an existing artificial recharge program in Santa Clara Valley in California. A computer groundwater model is used to estimate both the average long term and the drought period effects of artificial recharge in the study area. Results indicate that the costs of artificial recharge are considerably smaller than the alternative costs of an equivalent surface system. Refs.

Reichard, Eric G.; Bredehoeft, John D.

1984-01-01

252

Impact of Storm Water Recharge Practices on Boston Groundwater Elevations  

E-print Network

Impact of Storm Water Recharge Practices on Boston Groundwater Elevations Brian F. Thomas, S periodically experienced a decline in groundwater elevations and the associated deterioration of untreated wood piles, which support building foundations. To combat declining water tables, Boston enacted

Vogel, Richard M.

253

Reliability of Rechargeable Batteries in a Photovoltaic Power Supply System  

SciTech Connect

We investigate the reliability If a rechargeable battery acting as the energy storage component in a photovoltaic power supply system. A model system was constructed for this that includes the solar resource, the photovoltaic power supp Iy system, the rechargeable battery and a load. The solar resource and the system load are modeled as SI ochastic processes. The photovoltaic system and the rechargeable battery are modeled deterministically, imd an artificial neural network is incorporated into the model of the rechargeable battery to simulate dartage that occurs during deep discharge cycles. The equations governing system behavior are solved simultaneously in the Monte Carlo framework and a fwst passage problem is solved to assess system reliability.

Barney, P.; Jungst, R.G., Ingersoll, D.; O'Gorman, C.; Paez, T.L.; Urbina, A.

1998-11-30

254

Soil Water Balance and Recharge Monitoring at the Hanford Site – FY 2010 Status Report  

SciTech Connect

This report summarizes the recharge data collected in FY 2010 at five locations on the Hanford Site in southeastern Washington State. Average monthly precipitation and temperature conditions in FY 2010 were near normal and did not present an opportunity for increased recharge. The recharge monitoring data confirmed those conditions, showing normal behavior in water content, matric head, and recharge rates. Also provided in this report is a strategy for recharge estimation for the next 5 years.

Fayer, Michael J.; Saunders, Danielle L.; Herrington, Ricky S.; Felmy, Diana

2010-10-27

255

Cryogenic Transport of High-Pressure-System Recharge Gas  

NASA Technical Reports Server (NTRS)

A method of relatively safe, compact, efficient recharging of a high-pressure room-temperature gas supply has been proposed. In this method, the gas would be liquefied at the source for transport as a cryogenic fluid at or slightly above atmospheric pressure. Upon reaching the destination, a simple heating/expansion process would be used to (1) convert the transported cryogenic fluid to the room-temperature, high-pressure gaseous form in which it is intended to be utilized and (2) transfer the resulting gas to the storage tank of the system to be recharged. In conventional practice for recharging high-pressure-gas systems, gases are transported at room temperature in high-pressure tanks. For recharging a given system to a specified pressure, a transport tank must contain the recharge gas at a much higher pressure. At the destination, the transport tank is connected to the system storage tank to be recharged, and the pressures in the transport tank and the system storage tank are allowed to equalize. One major disadvantage of the conventional approach is that the high transport pressure poses a hazard. Another disadvantage is the waste of a significant amount of recharge gas. Because the transport tank is disconnected from the system storage tank when it is at the specified system recharge pressure, the transport tank still contains a significant amount of recharge gas (typically on the order of half of the amount transported) that cannot be used. In the proposed method, the cryogenic fluid would be transported in a suitably thermally insulated tank that would be capable of withstanding the recharge pressure of the destination tank. The tank would be equipped with quick-disconnect fluid-transfer fittings and with a low-power electric heater (which would not be used during transport). In preparation for transport, a relief valve would be attached via one of the quick-disconnect fittings (see figure). During transport, the interior of the tank would be kept at a near-ambient pressure far below the recharge pressure. As leakage of heat into the tank caused vaporization of the cryogenic fluid, the resulting gas would be vented through the relief valve, which would be set to maintain the pressure in the tank at the transport value. Inasmuch as the density of a cryogenic fluid at atmospheric pressure greatly exceeds that of the corresponding gas in a practical high-pressure tank at room temperature, a tank for transporting a given mass of gas according to the proposed method could be smaller (and, hence, less massive) than is a tank needed for transporting the same mass of gas according to the conventional method.

Ungar, Eugene K,; Ruemmele, Warren P.; Bohannon, Carl

2010-01-01

256

Hydrogeological Methods for Assessing Feasibility of Artificial Recharge  

NASA Astrophysics Data System (ADS)

This study presents the hydrogeological methods to assess the feasibility of artificial recharge in Jeju Island, Korea for securing both sustainable groundwater resources and severe floods. Jeju-friendly Aquifer Recharge Technology (J-ART) in this study is developing by capturing ephemeral stream water with no interference in the environments such as natural recharge or eco-system, storing the flood water in the reservoirs, recharging it through designed borehole after appropriate water treatment, and then making it to be used at down-gradient production wells. Many hydrogeological methods, including physico-chemical surface water and groundwater monitoring, geophysical survey, stable isotope analysis, and groundwater modeling have been employed to predict and assess the artificially recharged surface waters flow and circulation between recharge area and discharge area. In the study of physico-chemical water monitoring survey, the analyses of surface water level and velocity, of water qualities including turbidity, and of suspended soil settling velocity were performed. For understanding subsurface hydrogeologic characteristics the injection test was executed and the results are 118-336 m2/day of transmissivity and 4,367-11,032 m3/day of the maximum intake water capacity. Characterizing groundwater flow from recharge area to discharge area should be achieved to assess the efficiency of J-ART. The resistivity logging was carried out to predict water flow in unsaturated zone during artificial recharge based on the inverse modeling and resistivity change patterns. Stable isotopes of deuterium and oxygen-18 of surface waters and groundwaters have been determined to interpret mixing and flow in groundwaters impacted by artificial recharge. A numerical model simulating groundwater flow and heat transport to assess feasibility of artificial recharge has been developed using the hydraulic properties of aquifers, groundwater levels, borehole temperatures, and meteorological data. Also, groundwater modeling was performed to aid in artificial recharge system design, such as optimizing number and spacing of injection wells, building up and maintaining a water column inside each operating injection well, and optimizing time. Acknowledgements This research was supported by a grant (code 3-2-3) from the Sustainable Water Resources Research Center of 21st Century Frontier Research Program and the Basic Research Program (09-3414) of KIGAM.

Kim, Y.; Koo, M.; Lee, K.; Moon, D.; Barry, J. M.

2009-12-01

257

Thermal and Electrical Recharging of Sodium/Sulfur Cells  

NASA Technical Reports Server (NTRS)

Efficiency as high as 60 percent achieved. Proposed thermal and electrical recharging scheme expected to increase overall energy efficiency of battery of sodium/sulfur cells (beta cells). Takes advantage of peculiarity in chemical kinetics of recharge portion of operating cycle to give thermal assist to electrically driven chemical reactions. Future application include portable power supplies and energy storage in commercial power systems during offpeak periods.

Richter, Robert

1987-01-01

258

Future prospects of artifical groundwater recharge. [Disposal wells  

Microsoft Academic Search

Storing water underground has the advantages of minimizing evapotranspiration losses, equalizing water temperatures, providing natural filtration, and insuring a protected local water supply during times of emergency. More than 400 cities in the U.S. now use their treated effluent for agricultural irrigation or ground-water recharge. Water reclamation systems may be classified into infiltration basins, ridge-and-furrow, spray-irrigation, spray-runoff, and recharge wells.

1971-01-01

259

Ground water recharge and flow characterization using multiple isotopes.  

PubMed

Stable isotopes of delta(18)O, delta(2)H, and (13)C, radiogenic isotopes of (14)C and (3)H, and ground water chemical compositions were used to distinguish ground water, recharge areas, and possible recharge processes in an arid zone, fault-bounded alluvial aquifer. Recharge mainly occurs through exposed stream channel beds as opposed to subsurface inflow along mountain fronts. This recharge distribution pattern may also occur in other fault-bounded aquifers, with important implications for conceptualization of ground water flow systems, development of ground water models, and ground water resource management. Ground water along the mountain front near the basin margins contains low delta(18)O, (14)C (percent modern carbon [pmC]), and (3)H (tritium units [TU]), suggesting older recharge. In addition, water levels lie at greater depths, and basin-bounding faults that locally act as a flow barrier may further reduce subsurface inflow into the aquifer along the mountain front. Chemical differences in ground water composition, attributed to varying aquifer mineralogy and recharge processes, further discriminate the basin-margin and the basin-center water. Direct recharge through the indurated sandstones and mudstones in the basin center is minimal. Modern recharge in the aquifer is mainly through the broad, exposed stream channel beds containing coarse sand and gravel where ground water contains higher delta(18)O, (14)C (pmC), and (3)H (TU). Spatial differences in delta(18)O, (14)C (pmC), and (3)H (TU) and occurrences of extensive mudstones in the basin center suggest sluggish ground water movement, including local compartmentalization of the flow system. PMID:18384592

Chowdhury, Ali H; Uliana, Matthew; Wade, Shirley

2008-01-01

260

Seasonal variation in natural recharge of coastal aquifers  

NASA Astrophysics Data System (ADS)

Many coastal zones around the world have irregular precipitation throughout the year. This results in discontinuous natural recharge of coastal aquifers, which affects the size of freshwater lenses present in sandy deposits. Temperature data for the period 1960-1990 from LocClim (local climate estimator) and those obtained from the Intergovernmental Panel on Climate Change (IPCC) SRES A1b scenario for 2070-2100, have been used to calculate the potential evapotranspiration with the Thornthwaite method. Potential recharge (difference between precipitation and potential evapotranspiration) was defined at 12 locations: Ameland (The Netherlands), Auckland and Wellington (New Zealand); Hong Kong (China); Ravenna (Italy), Mekong (Vietnam), Mumbai (India), New Jersey (USA), Nile Delta (Egypt), Kobe and Tokyo (Japan), and Singapore. The influence of variable/discontinuous recharge on the size of freshwater lenses was simulated with the SEAWAT model. The discrepancy between models with continuous and with discontinuous recharge is relatively small in areas where the total annual recharge is low (258-616 mm/year); but in places with Monsoon-dominated climate (e.g. Mumbai, with recharge up to 1,686 mm/year), the difference in freshwater-lens thickness between the discontinuous and the continuous model is larger (up to 5 m) and thus important to consider in numerical models that estimate freshwater availability.

Mollema, Pauline N.; Antonellini, Marco

2013-06-01

261

The Policy of "Pumping the Recharge" Is Out of Control  

NASA Astrophysics Data System (ADS)

Hydrogeologists have spent several scientific generations in understanding the source of water to well fields and the effects of wells on the interrelated surface water system. The benchmark is by Theis [1940], who emphasized that some groundwater is initially mined during aquifer development and, after sufficient time, well discharge will be made up by diminution of both rejected recharge and natural discharge. Rejected recharge is water that would reside in the aquifer, except for a lack of space available. Theis advised that a perennial safe yield is equivalent to the amount of rejected recharge and natural discharge that is "feasible to utilize." His term "feasible" may have anticipated many current issues about aquifer sustainability. Papers published this year on the Ogallala aquifer in the central United States and on the global groundwater "footprint" [Scanlon et al., 2012; Gleeson et al., 2012] focus on recharge as an index of sustainability and have been featured in the popular press. However, I argue in this Forum that natural recharge rates alone cannot serve to address the core policy question regarding sustainable aquifer conditions in response to well field stresses. For the sake of users of hydrologic guidance, advisors on this topic may wish to reconsider the safe nature of "pumping the recharge."

Balleau, W. Peter

2013-01-01

262

Recharge signal identification based on groundwater level observations.  

PubMed

This study applied a method of the rotated empirical orthogonal functions to directly decompose the space-time groundwater level variations and determine the potential recharge zones by investigating the correlation between the identified groundwater signals and the observed local rainfall records. The approach is used to analyze the spatiotemporal process of piezometric heads estimated by Bayesian maximum entropy method from monthly observations of 45 wells in 1999-2007 located in the Pingtung Plain of Taiwan. From the results, the primary potential recharge area is located at the proximal fan areas where the recharge process accounts for 88% of the spatiotemporal variations of piezometric heads in the study area. The decomposition of groundwater levels associated with rainfall can provide information on the recharge process since rainfall is an important contributor to groundwater recharge in semi-arid regions. Correlation analysis shows that the identified recharge closely associates with the temporal variation of the local precipitation with a delay of 1-2 months in the study area. PMID:22016042

Yu, Hwa-Lung; Chu, Hone-Jay

2012-10-01

263

Estimating aquifer channel recharge using optical data interpretation.  

PubMed

Recharge through intermittent and ephemeral stream channels is believed to be a primary aquifer recharge process in arid and semiarid environments. The intermittent nature of precipitation and flow events in these channels, and their often remote locations, makes direct flow and loss measurements difficult and expensive. Airborne and satellite optical images were interpreted to evaluate aquifer recharge due to stream losses on the Frio River in south-central Texas. Losses in the Frio River are believed to be a major contributor of recharge to the Edwards Aquifer. The results of this work indicate that interpretation of readily available remote sensing optical images can offer important insights into the spatial distribution of aquifer recharge from losing streams. In cases where upstream gauging data are available, simple visual analysis of the length of the flowing reach downstream from the gauging station can be used to estimate channel losses. In the case of the Frio River, the rate of channel loss estimated from the length of the flowing reach at low flows was about half of the loss rate calculated from in-stream gain-loss measurements. Analysis based on water-surface width and channel slope indicated that losses were mainly in a reach downstream of the mapped recharge zone. The analysis based on water-surface width, however, did not indicate that this method could yield accurate estimates of actual flow in pool and riffle streams, such as the Frio River and similar rivers draining the Edwards Plateau. PMID:21434908

Walter, Gary R; Necsoiu, Marius; McGinnis, Ronald

2012-01-01

264

Rechargeable Magnesium Batteries: Low-Cost Rechargeable Magnesium Batteries with High Energy Density  

SciTech Connect

BEEST Project: Pellion Technologies is developing rechargeable magnesium batteries that would enable an EV to travel 3 times farther than it could using Li-ion batteries. Prototype magnesium batteries demonstrate excellent electrochemical behavior; delivering thousands of charge cycles with very little fade. Nevertheless, these prototypes have always stored too little energy to be commercially viable. Pellion Technologies is working to overcome this challenge by rapidly screening potential storage materials using proprietary, high-throughput computer models. To date, 12,000 materials have been identified and analyzed. The resulting best materials have been electrochemically tested, yielding several very promising candidates.

None

2010-10-01

265

Advanced rechargeable sodium batteries with novel cathodes  

NASA Technical Reports Server (NTRS)

Various high energy density rechargeable batteries are being considered for future space applications. Of these, the sodium-sulfur battery is one of the leading candidates. The primary advantage is the high energy density (760 Wh/kg theoretical). Energy densities in excess of 180 Wh/kg were realized in practical batteries. Other technological advantages include its chemical simplicity, absence of self-discharge, and long cycle life possibility. More recently, other high temperature sodium batteries have come into the spotlight. These systems can be described as follow: Na/Beta Double Prime-Al2O3/NaAlCl4/Metal Dichloride Sodium/metal dichloride systems are colloquially known as the zebra system and are currently being developed for traction and load leveling applications. The sodium-metal dichloride systems appear to offer many of the same advantages of the Na/S system, especially in terms of energy density and chemical simplicity. The metal dichloride systems offer increased safety and good resistance to overcharge and operate over a wide range of temperatures from 150 to 400 C with less corrosion problems.

Distefano, S.; Ratnakumar, B. V.; Bankston, C. P.

1989-01-01

266

Quantifying Recharge in Semi-Arid Basins: Translating Impact of Climate Variability and Change on Groundwater Resources  

E-print Network

temperature (Barnett et al., 2008). Groundwater recharge is thus likely to be altered due to climate change and variability impacting groundwater resources. Our current knowledge of recharge rates is poor because recharge and change on recharge rates in the future (IPCC, 2007). In arid and semi-arid environments recharge

Fay, Noah

267

Coupling Stormwater Capture and Managed Aquifer Recharge  

NASA Astrophysics Data System (ADS)

We are quantifying the performance of a system that couples stormwater capture and managed aquifer recharge (MAR). Our field site is a working ranch in the Pajaro Valley, central coastal California, where runoff from ~125 acres of farmed and grazed land is directed into a 2.5-acre infiltration basin. Stormwater captured for MAR at this site would otherwise be routed off the property and eventually into the ocean. We instrumented the site prior to the start of the 2013 water year (1 October 2012) to measure local precipitation, total inflow to the basin, and point-specific infiltration rates across the bottom of the basin using heat as a tracer. We also deployed sediment measurement and collection instruments to quantify the amount, texture, and biochemical nature of sediment accumulating in the basin, and to evaluate associated maintenance requirements for the system. The 2013 water year was relatively dry, with total precipitation less than 50% of the long-term average for this region; most of this precipitation occurred in December 2012. Water level and flow records indicate 17 distinct rain events that generated runoff, most early in the water year. The total inflow to the infiltration basin was 4.1 x 104 m3, equivalent to ~33 ac-ft. During a water year with average precipitation, it appears that this system could collect 80-100 ac-ft of runoff. There was up to 10 cm of sediment accumulation in some parts of the infiltration basin by the end of the rainy season. Sediment samples collected at the end of the season are being processed for analysis of sediment distribution and character. Thermal data are being analyzed to calculate spatial and temporal variations in infiltration rates across the basin. These data will be combined to assess the efficacy of coupling stormwater capture and MAR, and can guide future projects in this region of high groundwater demand and limited resources.

Beganskas, S.; Hill, C. L.; Fisher, A. T.; Los Huertos, M.

2013-12-01

268

Arsenic release during managed aquifer recharge (MAR)  

NASA Astrophysics Data System (ADS)

The mobilization and addition of geogenic trace metals to groundwater is typically caused by anthropogenic perturbations of the physicochemical conditions in the aquifer. This can add dangerously high levels of toxins to groundwater, thus compromising its use as a source of drinking water. In several regions world-wide, aquifer storage and recovery (ASR), a form of managed aquifer recharge (MAR), faces the problem of arsenic release due to the injection of oxygenated storage water. To better understand this process we coupled geochemical reactive transport modeling to bench-scale leaching experiments to investigate and verify the mobilization of geogenic arsenic (As) under a range of redox conditions from an arsenic-rich pyrite bearing limestone aquifer in Central Florida. Modeling and experimental observations showed similar results and confirmed the following: (1) native groundwater and aquifer matrix, including pyrite, were in chemical equilibrium, thus preventing the release of As due to pyrite dissolution under ambient conditions; (2) mixing of oxygen-rich surface water with oxygen-depleted native groundwater changed the redox conditions and promoted the dissolution of pyrite, and (3) the behavior of As along a flow path was controlled by a complex series of interconnected reactions. This included the oxidative dissolution of pyrite and simultaneous sorption of As onto neo-formed hydrous ferric oxides (HFO), followed by the reductive dissolution of HFO and secondary release of adsorbed As under reducing conditions. Arsenic contamination of drinking water in these systems is thus controlled by the re-equilibration of the system to more reducing conditions rather than a purely oxidative process.

Pichler, T.; Lazareva, O.; Druschel, G.

2013-12-01

269

Design and simulation of lithium rechargeable batteries  

SciTech Connect

Lithium -based rechargeable batteries that utilize insertion electrodes are being considered for electric-vehicle applications because of their high energy density and inherent reversibility. General mathematical models are developed that apply to a wide range of lithium-based systems, including the recently commercialized lithium-ion cell. The modeling approach is macroscopic, using porous electrode theory to treat the composite insertion electrodes and concentrated solution theory to describe the transport processes in the solution phase. The insertion process itself is treated with a charge-transfer process at the surface obeying Butler-Volmer kinetics, followed by diffusion of the lithium ion into the host structure. These models are used to explore the phenomena that occur inside of lithium cells under conditions of discharge, charge, and during periods of relaxation. Also, in order to understand the phenomena that limit the high-rate discharge of these systems, we focus on the modeling of a particular system with well-characterized material properties and system parameters. The system chosen is a lithium-ion cell produced by Bellcore in Red Bank, NJ, consisting of a lithium-carbon negative electrode, a plasticized polymer electrolyte, and a lithium-manganese-oxide spinel positive electrode. This battery is being marketed for consumer electronic applications. The system is characterized experimentally in terms of its transport and thermodynamic properties, followed by detailed comparisons of simulation results with experimental discharge curves. Next, the optimization of this system for particular applications is explored based on Ragone plots of the specific energy versus average specific power provided by various designs.

Doyle, C.M.

1995-08-01

270

Factors affecting areas contributing recharge to wells in shallow aquifers  

USGS Publications Warehouse

The source of water to wells is ultimately the location where the water flowing to a well enters the boundary surface of the ground-water system. In ground-water systems that receive most of their water from areal recharge, the location of the water entering the ground-water system is at the water table. The area contributing recharge to a discharging well is the surface area that defines the location of the water entering the ground-water system at the water table that flows to the well and is eventually discharged from the well. The calculation of areas contributing recharge to wells is complex because flow paths in ground-water systems change in response to development, and the aquifer material in ground-water systems is heterogeneous and is hidden from direct observation . Hypothetical experiments were undertaken to show the complexities in the delineation of areas contributing recharge to wells. Four different 'cases' are examined to demonstrate the effect of different conceptualized aquifer frameworks on deterministically calculated areas contributing recharge. The main conclusion drawn from the experiments is that, in order to understand the cause and effect relations that affect the quality of water derived from wells, the importance and nature of the variability in the ground-waterflow system must be considered and accounted for in any efforts to 'protect' the water supply.

Reilly, Thomas E.; Pollock, David W.

1993-01-01

271

Groundwater recharge from Long Lake, Indiana Dunes National Lakeshore  

SciTech Connect

Long Lake, located between Lake Michigan and the Dune-complexes of Indiana Dunes, was formed during Pleistocene and Holocene epochs. The lake is currently being studied to understand the detailed hydrology. One of the objective of the study is to understand the hydrologic relationship between the lake and a water treatment holding pond to the northeast. Understanding the water movement between the two bodies of water, if any, would be very important in the management and protection of nature preserves in the area. Seepage measurement and minipiezometric tests indicate groundwater recharge from Long Lake. The groundwater recharge rate is approximately 1.40 to 22.28 x 10[sup [minus]4] m/day. An estimate of the amount of recharge of 7.0 x 10[sup 6] m[sup 3]/y may be significant in terms of groundwater recharge of the upper aquifer system of the Dunes area. The water chemistry of the two bodies of water appears to be similar, however, the pH of the holding pond is slightly alkaline (8.5) while that of Long Lake is less alkaline (7.7). There appears to be no direct contact between the two bodies of water (separated by approximately six meters of clay rich sediment). The geology of the area indicates a surficial aquifer underlying Long Lake. The lake should be regarded as a recharge area and should be protected from pollutants as the degradation of the lake would contaminate the underlying aquifer.

Isiorho, S.A.; Beeching, F.M. (Indiana Univ., Fort Wayne, IN (United States). Geosciences Dept.); Whitman, R.L.; Stewart, P.M. (National Park Services, Porter, IN (United States). Indiana Dunes National Lakeshore); Gentleman, M.A.

1992-01-01

272

Fate of human viruses in groundwater recharge systems  

SciTech Connect

The overall objective of this research program was to determine the ability of a well-managed tertiary effluent-recharge system to return virologically acceptable water to the groundwater aquifer. The study assessed the quality of waters renovated by indigenous recharge operations and investigated a number of virus-soil interrelationships. The elucidation of the interactions led to the establishment of basin operating criteria for optimizing virus removal. Raw influents, chlorinated tertiary effluents, and renovated wastewater from the aquifer directly beneath a uniquely designed recharge test basin were assayed on a weekly basis for the presence of human enteroviruses and coliform bacteria. High concentrations of viruses were routinely isolated from influents but were isolated only on four occasions from tertiary-treated sewage effluents. In spite of the high quality effluent being recharged, viruses were isolated from the groundwater observation well, indicating their ability to penetrate the unsaturated zone. Results of poliovirus seeding experiments carried out in the test basin clearly indicated the need to operate recharge basins at low (e.g. 1 cm/h) infiltration rates in areas having soil types similar to those found at the study site. The method selected for reducing the test basin infiltration rate involved clogging the basin surface with settled organic material from highly turbid effluent. Alternative methods for slowing infiltration rates are discussed in the text.

Vaughn, J.M.; Landry, E.F.

1980-03-01

273

The Effects of Recharge, Agricultural Pumping and Municipal Pumping on Springflow and Pumping Lifts Within the Edwards Aquifer  

E-print Network

The Effects of Recharge, Agricultural Pumping and Municipal Pumping on Springflow and Pumping Lifts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 The Effects of Recharge and Pumping Over Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 The Effects of Agricultural Pumping, Municipal Pumping and Recharge on Comal Springflow

McCarl, Bruce A.

274

The timing of EV recharging and its effect on utilities  

NASA Astrophysics Data System (ADS)

The impact of electric vehicles (EVs) on electric utilities will in part depend on when the vehicles are recharged. If electricity pricing practices were guided by time of day, recharging of EVs would occur at late night hours, when demand for electricity for other purposes is low. The peak demand by the year 2000 would then increase by only 400 MW, by comparison with 5700 MW for the case of electricity that is uniformly priced throughout the day. It is further established by the present projections that the oil- and gas-burning component of electrical generation would rise by only 27 percent for the late night-charging case, by contrast to 39 percent for the alternative, late afternoon and early evening recharging.

Collins, M. M.; Mader, G. H.

1983-02-01

275

Sulfone-based electrolytes for aluminium rechargeable batteries.  

PubMed

Electrolyte is a key material for success in the research and development of next-generation rechargeable batteries. Aluminium rechargeable batteries that use aluminium (Al) metals as anode materials are attractive candidates for next-generation batteries, though they have not been developed yet due to the lack of practically useful electrolytes. Here we present, for the first time, non-corrosive reversible Al electrolytes working at room temperature. The electrolytes are composed of aluminium chlorides, dialkylsulfones, and dilutants, which are realized by the identification of electrochemically active Al species, the study of sulfone dependences, the effects of aluminium chloride concentrations, dilutions and their optimizations. The characteristic feature of these materials is the lower chloride concentrations in the solutions than those in the conventional Al electrolytes, which allows us to use the Al metal anodes without corrosions. We anticipate that the sulfone-based electrolytes will open the doors for the research and development of Al rechargeable batteries. PMID:25627398

Nakayama, Yuri; Senda, Yui; Kawasaki, Hideki; Koshitani, Naoki; Hosoi, Shizuka; Kudo, Yoshihiro; Morioka, Hiroyuki; Nagamine, Masayuki

2015-02-10

276

Crab Burrows are Important Conduits for Groundwater Recharge in Bangladesh  

NASA Astrophysics Data System (ADS)

Recent research suggests that recharge from man-made ponds may stimulate arsenic mobilization within Bangladeshi aquifers. Man-made ponds are widespread throughout Bangladesh and are generally underlain by low permeability clays that could potentially limit flow to the sandy aquifer below if they are not compromised by preferential flow paths. Animal borrows are one common type of preferential flow path through surface clays. Across the Ganges Delta, terrestrial crabs dig borrows, sometimes as long as 10 meters. In our study pond in Munshiganj, Bangladesh we found crab burrows extending through the surficial clays and down into the shallow aquifer spaced approximately every meter. We use these field observations along with a novel, coupled isotope and water balance model to quantify the fluxes into and out of the pond. We show that nearly all of the aquifer recharge from the pond is through crab burrows which have enhanced the hydraulic conductivity of the surficial sediments by several orders of magnitude. In addition we show that the recharging pond water is shifting the solute composition of water beneath the pond. We suggest that, as a result of crab burrows, young ponds may contribute large fluxes of recharge water whereas older ponds may contribute little recharge to the aquifer. All terrestrial crabs have gills that must remain moist to allow for respiration. So, to ensure an uninterrupted water source, their borrows must reach the maximum depth that the water table drops to seasonally after irrigation ceases and before the onset of the monsoon. Once a pond is installed crabs living within the sediments that now make up the new pond bottom would no longer need to construct burrows to ensure a constant supply of water. Over time, burrows that existed prior to pond construction can clog. Water balance data for an old pond at our study site indicates that this pond contributes less recharge than our newly constructed pond.

Stahl, M.; Tarek, M. H.; Yeo, D. C.; Badruzzaman, A.; Harvey, C. F.

2013-12-01

277

Estimating ground water recharge from topography, hydrogeology, and land cover.  

PubMed

Proper management of ground water resources requires knowledge of the rates and spatial distribution of recharge to aquifers. This information is needed at scales ranging from that of individual communities to regional. This paper presents a methodology to calculate recharge from readily available ground surface information without long-term monitoring. The method is viewed as providing a reasonable, but conservative, first approximation of recharge, which can then be fine-tuned with other methods as time permits. Stream baseflow was measured as a surrogate for recharge in small watersheds in southeastern Wisconsin. It is equated to recharge (R) and then normalized to observed annual precipitation (P). Regression analysis was constrained by requiring that the independent and dependent variables be dimensionally consistent. It shows that R/P is controlled by three dimensionless ratios: (1) infiltrating to overland water flux, (2) vertical to lateral distance water must travel, and (3) percentage of land cover in the natural state. The individual watershed properties that comprise these ratios are now commonly available in GIS data bases. The empirical relationship for predicting R/P developed for the study watersheds is shown to be statistically viable and is then tested outside the study area and against other methods of calculating recharge. The method produces values that agree with baseflow separation from streamflow hydrographs (to within 15% to 20%), ground water budget analysis (4%), well hydrograph analysis (12%), and a distributed-parameter watershed model calibrated to total streamflow (18%). It has also reproduced the temporal variation over 5 yr observed at a well site with an average error < 12%. PMID:15726928

Cherkauer, Douglas S; Ansari, Sajjad A

2005-01-01

278

Inorganic electrolyte Li/CuCl2 rechargeable cell  

NASA Astrophysics Data System (ADS)

A rechargeable lithium battery using a cathode of copper(II) chloride and an electrolyte consisting of LiAlCl4.3SO2 has been developed. The efficiency of lithium plating was evaluated in lithium-limited prototype cells. Cathode rechargeability was evaluated in cathode-limited prototypes, and system energy density was demonstrated by use of a wound D cell. The use of an electrolyte system which reacts reversibly with metallic lithium allowed the use of systematic overcharge to eliminate irreversible loss of lithium from the system and to provide for cell balancing. Lithium cycling figures of merit as high as 190 were attained by use of the overcharging.

Dey, A. N.; Bowden, W. L.; Kuo, H. C.; Gopikanth, M. L.; Schlaikjer, C.

1989-06-01

279

Thin Rechargeable Batteries for CMOS SRAM Memory Protection  

NASA Technical Reports Server (NTRS)

New rechargeable battery technology is described and compared with classical primary battery back-up of SRAM PC cards. Thin solid polymer electrolyte cells with the thickness of TSOP memory components (1 mm nominal, 1.1 mm max) and capacities of 14 mAh/sq cm can replace coin cells. The SRAM PC cards with permanently installed rechargeable cells and optional electrochromic low battery voltage indicators will free the periodic PC card user from having to 'feed' their PC cards with coin cells and will allow a quick visual check of stored cards for their battery voltage status.

Crouse, Dennis N.

1993-01-01

280

Modelling of recharge and pollutant fluxes to urban groundwaters.  

PubMed

Urban groundwater resources are of considerable importance to the long-term viability of many cities world-wide, yet prediction of the quantity and quality of recharge is only rarely attempted at anything other than a very basic level. This paper describes the development of UGIf, a simple model written within a GIS, designed to provide estimates of spatially distributed recharge and recharge water quality in unconfined but covered aquifers. The following processes (with their calculation method indicated) are included: runoff and interception (curve number method); evapotranspiration (Penman-Grindley); interflow (empirical index approach); volatilization (Henry's law); sorption (distribution coefficient); and degradation (first order decay). The input data required are: meteorological data, landuse/cover map with event mean concentration attributes, geological maps with hydraulic and geochemical attributes, and topographic and water table elevation data in grid form. Standard outputs include distributions of: surface runoff, infiltration, potential recharge, ground level slope, interflow, actual recharge, pollutant fluxes in surface runoff, travel times of each pollutant through the unsaturated zone, and the pollutant fluxes and concentrations at the water table. The process of validation has commenced with a study of the Triassic Sandstone aquifer underlying Birmingham, UK. UGIf predicts a similar average recharge rate for the aquifer as previous groundwater flow modelling studies, but with significantly more spatial detail: in particular the results indicate that recharge through paved areas may be more important than previously thought. The results also highlight the need for more knowledge/data on the following: runoff estimation; interflow (including the effects of lateral flow and channelling on flow times and therefore chemistry); evapotranspiration in paved areas; the nature of unsaturated zone flow below paved areas; and the role of the pipe network. Although considerably more verification is needed, UGIf shows promise for use: in providing input for regional groundwater solute transport models; in identifying gaps in knowledge and data; in determining which processes are the most important influences on urban groundwater quantity and quality; in evaluating existing recharge models; in planning, for example in investigation of the effects of landuse or climate change; and in assessing groundwater vulnerability. PMID:16325236

Thomas, Abraham; Tellam, John

2006-05-01

281

Rechargeable room-temperature CF(x)-sodium battery.  

PubMed

Here we demonstrate for the first time that CFx cathodes show rechargeable capability in sodium ion batteries with an initial discharge capacity of 1061 mAh g(-1) and a reversible discharge capacity of 786 mAh g(-1). The highly reversible electrochemical reactivity of CFx with Na at room temperature indicates that the decomposition of NaF could be driven by carbon formed during the first discharge. The high reversible capacity made it become a promising cathode material for future rechargeable sodium batteries. PMID:24494989

Liu, Wen; Li, Hong; Xie, Jing-Ying; Fu, Zheng-Wen

2014-02-26

282

Focused Ground-Water Recharge in the Amargosa Desert Basin  

USGS Publications Warehouse

The Amargosa River is an approximately 300-kilometer long regional drainage connecting the northern highlands on the Nevada Test Site in Nye County, Nev., to the floor of Death Valley in Inyo County, Calif. Streamflow analysis indicates that the Amargosa Desert portion of the river is dry more than 98 percent of the time. Infiltration losses during ephemeral flows of the Amargosa River and Fortymile Wash provide the main sources of ground-water recharge on the desert-basin floor. The primary use of ground water is for irrigated agriculture. The current study examined ground-water recharge from ephemeral flows in the Amargosa River by using streamflow data and environmental tracers. The USGS streamflow-gaging station at Beatty, Nev., provided high-frequency data on base flow and storm runoff entering the basin during water years 1998?2001. Discharge into the basin during the four-year period totaled 3.03 million cubic meters, three quarters of which was base flow. Streambed temperature anomalies indicated the distribution of ephemeral flows and infiltration losses within the basin. Major storms that produced regional flow during the four-year period occurred in February 1998, during a strong El Ni?o that more than doubled annual precipitation, and in July 1999. The study also quantified recharge beneath undisturbed native vegetation and irrigation return flow beneath irrigated fields. Vertical profiles of water potential and environmental tracers in the unsaturated zone provided estimates of recharge beneath the river channel (0.04?0.09 meter per year) and irrigated fields (0.1?0.5 meter per year). Chloride mass-balance estimates indicate that 12?15 percent of channel infiltration becomes ground-water recharge, together with 9?22 percent of infiltrated irrigation. Profiles of potential and chloride beneath the dominant desert-shrub vegetation suggest that ground-water recharge has been negligible throughout most of the basin since at least the early Holocene. Surface-based electrical-resistivity imaging provided areal extension of borehole information from sampled profiles. These images indicate narrowly focused recharge beneath the Amargosa River channel, flanked by large tracts of recharge-free basin floor.

Stonestrom, David A.; Prudic, David E.; Walvoord, Michelle A.; Abraham, Jared D.; Stewart-Deaker, Amy E.; Glancy, Patrick A.; Constantz, Jim; Laczniak, Randell J.; Andraski, Brian J.

2007-01-01

283

Ag nanoparticles-anchored reduced graphene oxide catalyst for oxygen electrode reaction in aqueous electrolytes and also a non-aqueous electrolyte for Li-O2 cells.  

PubMed

Silver nanoparticles-anchored reduced graphene oxide (Ag-RGO) is prepared by simultaneous reduction of graphene oxide and Ag(+) ions in an aqueous medium by ethylene glycol as the reducing agent. Ag particles of average size of 4.7 nm were uniformly distributed on the RGO sheets. Oxygen reduction reaction (ORR) is studied on Ag-RGO catalyst in both aqueous and non-aqueous electrolytes by using cyclic voltammetry and rotating disk electrode techniques. As the interest in non-aqueous electrolyte is to study the catalytic performance of Ag-RGO for rechargeable Li-O2 cells, these cells are assembled and characterized. Li-O2 cells with Ag-RGO as the oxygen electrode catalyst are subjected to charge-discharge cycling at several current densities. A discharge capacity of 11?950 mA h g(-1) (11.29 mA h cm(-2)) is obtained initially at low current density. Although there is a decrease in the capacity on repeated discharge-charge cycling initially, a stable capacity is observed for about 30 cycles. The results indicate that Ag-RGO is a suitable catalyst for rechargeable Li-O2 cells. PMID:25242373

Kumar, Surender; Selvaraj, C; Scanlon, L G; Munichandraiah, N

2014-11-01

284

Estimation of Recharge to the Middle Trinity Aquifer of Central Texas Using Water-Level Fluctuations  

E-print Network

in the study area, comprising about 4500 square miles. The results of the investigation yielded a method of recharge calculation different from the stream baseflow method now in use. The recharge values obtained by this study were substantially less than...

Jennings, Marshall; Chad, Thomas; Burch, John; Creutzburg, Brian; Lambert, Lance

285

Rechargeability improvement of ?-type chemical manganese dioxide with the co-doping of Bi and Ni in alkaline electrolyte  

NASA Astrophysics Data System (ADS)

?-MnO2 with the doping of Ni and Bi was prepared through a simple chemical precipitation/oxidation method. Its structure was confirmed by the X-ray diffraction tests. The results of cyclic voltammetry and galvanostatic charge-discharge tests showed that both the doping of Bi and Ni benefited the electrochemical activity of the MnO2 electrode. Compared to the un-doped electrode, the Bi-doped one showed larger discharge capacity and the Ni-doped one showed higher discharge potential and better cycleability. With the co-doping of 5 wt% Bi and 10 wt% Ni, the discharge capacity of the MnO2 electrode reached 252 mA h g-1 at a 0.2C rate and 116 mA h g-1 at a 1C rate, respectively. Its capacity remained in 105 mA h g-1 after 50 cycles at a 1C rate, but the capacity of a commercial electrolytic MnO2 electrode was only 37 mA h g-1.

Li, Xiaofeng; Li, Zheng; Xia, Tongchi; Dong, Huichao; Song, Yanhua; Wang, Lizhen

2012-10-01

286

Characterizing Field Biodegradation of N-nitrosodimethylamine (NDMA) in Groundwater with Active Reclaimed Water Recharge  

NASA Astrophysics Data System (ADS)

N-Nitrosodimethylamine (NDMA) is an emerging contaminant in groundwater, because of its aqueous miscibility, exceptional animal toxicity, and human carcinogenicity. NDMA detections in groundwater have been tracked to either decomposition of unsymmetrical dimethylhydrazine (UDMH) used in rocket fuel facilities or chlorine disinfection in wastewater reclamation plants. Laboratory experiments on both unsaturated and saturated soil samples have demonstrated that NDMA can be biodegraded by microbial activity, under both aerobic and anaerobic conditions. However, very limited direct evidence for its biodegradation has been found from the field in saturated groundwater. Our research aimed to evaluate photolysis and biodegradation of NDMA occurring along the full travel path - from wastewater reclamation plant effluent, through rivers and spreading grounds, to groundwater. For this evaluation, we established an extensive monitoring network to characterize NDMA concentrations at effluent discharge points, surface water stations, and groundwater monitoring and production wells, during the operation of the Montebello Forebay Groundwater Recharge facilities in Los Angeles County, California. Field monitoring for NDMA has been conducted for more than six years, including 32 months of relatively lower NDMA concentrations in effluent, 43 months of elevated NDMA effluent concentrations, and 7 months with significantly reduced NDMA effluent concentrations. The NDMA effluent concentration increase and significant concentration decrease were caused by changes in treatment processes. The NDMA sampling data imply that significant biodegradation occurred in groundwater, accounting for a 90% mass reduction of NDMA over the six-year monitoring period. In addition, the occurrence of a discrete well monitored effluent release during the study period allowed critical analysis of the fate of NDMA in a well- characterized, localized groundwater flow subsystem. The data indicate that 80% of the recharged NDMA mass was biodegraded in groundwater with the remaining mass pumped out by extraction wells. To reproduce the observation data, a groundwater flow and transport model was developed and calibrated against groundwater elevation and NDMA concentration data. The calibrated half-life of NDMA in groundwater is 69 days, which is consistent with the values obtained through laboratory incubation using soil samples from the Montebello Forebay Spreading Grounds. Given the photolysis of NDMA in surface water and biodegradation in groundwater observed during this study, reclaimed wastewater with limited NDMA concentrations can be safely used for groundwater recharge under the study area conditions.

McCraven, S.; Zhou, Q.; Garcia, J.; Gasca, M.; Johnson, T.

2007-12-01

287

Diffuse groundwater recharge in semiarid environments: interactions between climate and soil texture  

Microsoft Academic Search

Previous research, primarily based on environmental tracer techniques, has demonstrated that diffuse recharge in semiarid environments varies greatly through space and time. Typically, there is no diffuse recharge at low-elevation sites in semiarid regions, whereas diffuse recharge often occurs at higher elevations. While there has been no diffuse recharge at low-elevation sites over the past ˜ 10^4 yr, it is

E. Small

2003-01-01

288

Derived Operating Rules for Allocating Recharges and Withdrawals among Unconnected Aquifers  

E-print Network

the future availability of water for extraction influence recharge and withdrawal decisions. DOI: 10Derived Operating Rules for Allocating Recharges and Withdrawals among Unconnected Aquifers David E and recharge of water in multiple, unconnected aquifers. Management objectives are: 1 minimizing costs; 2

Pasternack, Gregory B.

289

Climate change impacts on groundwater recharge uncertainty, shortcomings, and the way forward?  

Microsoft Academic Search

An integrated approach to assessing the regional impacts of climate and socio-economic change on groundwater recharge is described from East Anglia, UK. Many factors affect future groundwater recharge including changed precipitation and temperature regimes, coastal flooding, urbanization, woodland establishment, and changes in cropping and rotations. Important sources of uncertainty and shortcomings in recharge estimation are discussed in the light of

I. P. Holman

2006-01-01

290

Impact of deep plowing on groundwater recharge in a semiarid region  

E-print Network

Impact of deep plowing on groundwater recharge in a semiarid region: Case study, High Plains, Texas September 2008; accepted 17 September 2008; published 20 December 2008. [1] Groundwater recharge is critical in rainfed (nonirrigated) agriculture in a semiarid region on groundwater recharge, which had not been

Scanlon, Bridget R.

291

THE SENSITIVITY OF NORTHERN GROUNDWATER RECHARGE TO CLIMATE CHANGE: A CASE STUDY IN NORTHWEST ALASKA1  

E-print Network

THE SENSITIVITY OF NORTHERN GROUNDWATER RECHARGE TO CLIMATE CHANGE: A CASE STUDY IN NORTHWEST WSE and snow depth compared well with PWBM-simulated groundwater recharge and snow storage. Using to sustain sufficient groundwater recharge. (KEY TERMS: climate variability/change; arctic /antarctic

Massachusetts at Amherst, University of

292

The impact of climate change on spatially varying groundwater recharge in the grand river watershed (Ontario)  

Microsoft Academic Search

Understanding the process of groundwater recharge is fundamental to the management of groundwater resources. Quantifying the future evolution of recharge over time requires not only the reliable forecasting of changes in key climatic variables, but also modelling their impact on the spatially varying recharge process. This paper presents a physically based methodology that can be used to characterize both the

Mikko I. Jyrkama; Jon F. Sykes

2007-01-01

293

Climate change impacts on groundwater recharge uncertainty, shortcomings, and the way forward?  

Microsoft Academic Search

An integrated approach to assessing the regional impacts of climate and socio-economic change on groundwater recharge is described from East Anglia, UK. Many factors affect future groundwater recharge including changed precipitation and temperature regimes, coastal flooding, urbanization, woodland establishment, and changes in cropping and rotations.Important sources of uncertainty and shortcomings in recharge estimation are discussed in the light of the

I. P. Holman

2006-01-01

294

Recharge in Karst Shrublands of Central Texas: Monitoring Drip Rates in Shallow Caves  

Microsoft Academic Search

The exceedingly complex subsurface hydrology of karst landscapes presents formidable challenges to understanding recharge rates and the relationships between rainfall and recharge. In this study, we have established a network of drip collectors and monitoring stations in shallow caves in the Edwards Plateau to better understand the dynamics of recharge and eventually for determining the effect of woody plants on

R. A. Bazan; B. P. Wilcox; C. L. Munster; K. Owens; B. Shade

2007-01-01

295

USGS Professional Paper 1703--Ground-Water Recharge in the Arid and Semiarid Southwestern United States--  

E-print Network

USGS Professional Paper 1703--Ground-Water Recharge in the Arid and Semiarid Southwestern United States-- Appendix--1 Thermal Methods for Investigating Ground-Water Recharge By Kyle W. Blasch, Jim is defined as the downward flux of water across the regional water table. The introduction of recharging

296

Spatial Variability of Ground-Water Recharge Estimates in the Glassboro Area, New Jersey  

Microsoft Academic Search

The spatial variability of ground-water recharge estimates in the Glassboro area, NJ, was evaluated using geostatistical methods as a preliminarily assessment of aquifer vulnerability. Recharge was estimated using Darcy's law, based on parameters obtained from pedotransfer functions applied to measured soil texture values. The recharge estimates correspond to sediments overlying the Kirkwood-Cohansey aquifer, which comprises highly permeable unconsolidated sands and

B. T. Nolan; A. L. Baehr

2001-01-01

297

WASTEWATER CONTAMINATE REMOVAL FOR GROUNDWATER RECHARGE AT WATER FACTORY 21  

EPA Science Inventory

This is the second report in a series which describes the performance of Water Factory 21, a 0.66 cu m/s advanced wastewater treatment plant designed to reclaim secondary effluent from a municipal wastewater treatment plant so that it can be used for injection and recharge of a g...

298

LOCALIZED RECHARGE INFLUENCES ON MTBE TRANSPORT AND WELL PLACEMENT CONSIDERATIONS  

EPA Science Inventory

Vertical characterization of a gasoline release site at East Patchogue, New York showed that methyl tert-butyl ether (MTBE) and aromatic plumes "dived" as they passed beneath a sand pit. That this behavior was caused by aquifer recharge was shown by two pieces of evidence. Fir...

299

College of Chemistry Recharge Rates Computer Graphics Laboratory  

E-print Network

College of Chemistry Recharge Rates Computer Graphics Laboratory Computational Services (effective at cost Linux/Pitzer Center support (effective July 1, 2014) Pitzer Center support $67.00/hour Chemistry & Store Room (effective July 1, 2014) Store Room Cost + 25.60% Compressed Gases Cost + 25% Demurrage $13

Doudna, Jennifer A.

300

PRIORITY POLLUTANTS IN THE CEDAR CREEK WASTEWATER RECLAMATION - RECHARGE FACILITIES  

EPA Science Inventory

The Cedar Creek Wastewater Reclamation Plant (CCWRP) located in Nassau County, NY is a 0.24 cu m/s (5.5 mgd) advanced wastewater treatment (AWT) plant designed to produce a high quality effluent suitable for groundwater recharge. The CCWRP was constructed as a demonstration proje...

301

Wave energy systems for recharging AUV energy supplies  

Microsoft Academic Search

This paper describes ocean wave energy resources and characterizes their global distribution and temporal variability. It presents an overview of wave energy conversion devices that have progressed beyond the laboratory wave tank and have been proven at sea, and which lend themselves to miniaturization and packaging in a configuration suitable for recharging AUV power supplies from a docking station base.

George Hagerman

2002-01-01

302

Oxygen electrodes for rechargeable alkaline fuel cells. II  

NASA Technical Reports Server (NTRS)

The primary objective of this program is the investigation and development of electrocatalysts and supports for the positive electrode of moderate temperature, single-unit, rechargeable alkaline fuel cells. Approximately six support materials and five catalyst materials have been identified to date for further development.

Swette, L.; Kackley, N.

1990-01-01

303

Oxygen electrodes for rechargeable alkaline fuel cells-II  

NASA Technical Reports Server (NTRS)

The primary objective of this program is the investigation and development of electrocatalysts and supports for the positive electrode of moderate temperature single-unit rechargeable alkaline fuel cells. Approximately six support materials and five catalyst materials have been identified to date for further development.

Swette, L.; Kackley, N.

1989-01-01

304

Oxygen electrodes for rechargeable alkaline fuel cells, 3  

NASA Technical Reports Server (NTRS)

The investigation and development of electrocatalysts and supports for the positive electrode of moderate temperature single unit rechargeable alkaline fuel cells is described. Focus is on chemical and electrochemical stability and O2 reduction/evolution activity of the electrode in question.

Swette, L.; Kackley, N.; Mccatty, S. A.

1991-01-01

305

Modelling the groundwater recharge of an urban area in Germany  

Microsoft Academic Search

Groundwater recharge is an important part of the natural water cycle. This cycle is disturbed particularly in urban areas. Sealing negatively influences the hydrological and mechanical soil properties. The continued sealing of soils, mainly caused by urbanisation, will continue to reduce the infiltration of water to groundwater and increase the surface run-off. Furthermore, recent and future climate changes strongly affect

Sabine Tesch; Volkmar Dunger; Jörg Matschullat

2010-01-01

306

Climate change effects on vegetation characteristics and groundwater recharge  

Microsoft Academic Search

Climate change is among the most pressing issues of our time. Increase in temperature, a decrease in summer precipitation and increase in reference evapotranspiration might affect the water balance, freshwater availability and the spatial distribution and type of vegetation. Precipitation and evapotranspiration (ET) largely determine groundwater recharge. Therefore, climate change likely affects both the spatial and temporal freshwater availability for

2010-01-01

307

On the Fate of Artificial Recharge in a Coastal Aquifer  

Microsoft Academic Search

The increased use of reclaimed water for artificial groundwater recharge purposes has led to concerns about future groundwater quality, particularly as it relates to the introduction of new organic and inorganic contaminants into the subsurface. Here we review the integrated application of isotopic characterization and numerical modeling techniques for assessing the migration of reclaimed water that is used for artificial

A. Tompson; M. Davisson; R. Maxwell; G. Hudson; C. Welty; S. Carle; N. Rosenberg

308

Interdisciplinary Institute for Innovation Optimal Recharging Strategy for  

E-print Network

while the Spanish government has committed to having 1 million electric or hybrid cars on Spanish roads price differentials in electricity tariffs are designed to dissuade car owners from recharging for Electric Vehicles in France Margaret Armstrong Charles El Hajj Moussa Jérôme Adnot Alain Galli Philippe

Paris-Sud XI, Université de

309

Groundwater drainage and recharge by networks of irregular channels  

Microsoft Academic Search

A linear complementarity theory is proposed for the coupled treatment of groundwater seepage and surface runoff along a sloping plane ground perturbed by irregular channels. Steady downslope routing is applied to the two-dimensional overland flow, while Green functions are used to relate the three-dimensional groundwater motion to the surface drainage and recharge distribution. The coupling between the surface and subsurface

Wei-Jay Ni; Hervé Capart

2006-01-01

310

Net Recharge Targets to meet Regional Environmental Goals  

E-print Network

. Building on the previous hydrogeology studies in the CIA, further work was carried out to quantify vertical. This project is aimed at investigating the following groundwater management issues in the CIA: · Characterise and discharge zones in the CIA. Currently the overall recharge area is around 30 percent of the region

Khan, Shahbaz

311

Encouraging Revegetation in Australia with a Groundwater Recharge Credit Scheme  

Microsoft Academic Search

This paper describes a comprehensive method to design, test and then implement a Payments for Ecosystem Services (PES) framework to combat the environmental consequences of extensive native vegetation clearance in Australia. Clearing of vegetation, primarily due to the expansion of farming areas, has often resulted in regional dryland and irrigation salinity. The market based approach adopted ? a groundwater recharge

Wendy Proctor; Jeffery D. Connor; John Ward; Darla Hatton MacDonald

2007-01-01

312

HOW TO PURCHASE CREDITS OR RECHARGE THE CARD: Preliminaryremarks  

E-print Network

to purchase credits or recharge the bike sharing card is a service provided and managed by velopass sarl. The USI has nothing to do with the management and organization of the bike sharing service for the velopass online shop, you need to do it (it's free) by selecting on the left the button "Registrati

Krause, Rolf

313

Methods Note/ Net Recharge vs. Depth to Groundwater  

E-print Network

soils with a shallow groundwater table. The transition depth (dt) between negative and positive valuesMethods Note/ Net Recharge vs. Depth to Groundwater Relationship in the Platte River Valley rates were correlated with depth to groundwater (d) values in the wide alluvial valley of the Platte

Szilagyi, Jozsef

314

Estimating High Plains Aquifer Recharge Using Temperature Probes  

Technology Transfer Automated Retrieval System (TEKTRAN)

The magnitude of recharge through playa wetlands in the High Plains Region of the United States has been debated, but rarely quantified. The ephemeral nature of water in playas makes it difficult and expensive to observe filling and drying/draining cycles. Inexpensive tools are needed to quantify ...

315

DELINEATING KARST RECHARGE AREAS AT ONONDAGA CAVE STATE PARK  

Technology Transfer Automated Retrieval System (TEKTRAN)

Onondaga Cave State Park is located in the north central portion of the Ozarks near Leasburg, Missouri. The park is known for two extensive cave systems, Onondaga Cave and Cathedral Cave. Both of these cave systems have active streams (1-2 cfs at baseflow) which have unknown recharge areas. As a man...

316

THE ROLE OF UNSATURATED FLOW IN ARTIFICAL RECHARGE PROJECTS  

Microsoft Academic Search

The hydrogeology of the unsaturated zone plays a critical role in determining the suitability of a site for artificial recharge. Optimally, a suitable site has highly permeable soils, capacity for horizontal flow at the aquifer boundary, lack of impeding layers, and a thick unsaturated zone. The suitability of a site is often determined by field and laboratory measurements of soil

Alan L. Flint

317

A polymer electrolyte-based rechargeable lithium\\/oxygen battery  

Microsoft Academic Search

A novel rechargeable Li\\/Oâ battery is reported. It comprises a Li{sup +} conductive organic polymer electrolyte membrane sandwiched by a thin Li metal foil anode, and a thin carbon composite electrode on which oxygen, the electroactive cathode material, accessed from the environment, is reduced during discharge to generate electric power. It features an all solid state design in which electrode

K. M. Abraham; Z. Jiang

1996-01-01

318

Ecohydrologic process modeling of mountain block groundwater recharge.  

PubMed

Regional mountain block recharge (MBR) is a key component of alluvial basin aquifer systems typical of the western United States. Yet neither water scientists nor resource managers have a commonly available and reasonably invoked quantitative method to constrain MBR rates. Recent advances in landscape-scale ecohydrologic process modeling offer the possibility that meteorological data and land surface physical and vegetative conditions can be used to generate estimates of MBR. A water balance was generated for a temperate 24,600-ha mountain watershed, elevation 1565 to 3207 m, using the ecosystem process model Biome-BGC (BioGeochemical Cycles) (Running and Hunt 1993). Input data included remotely sensed landscape information and climate data generated with the Mountain Climate Simulator (MT-CLIM) (Running et al. 1987). Estimated mean annual MBR flux into the crystalline bedrock terrain is 99,000 m(3) /d, or approximately 19% of annual precipitation for the 2003 water year. Controls on MBR predictions include evapotranspiration (radiation limited in wet years and moisture limited in dry years), soil properties, vegetative ecotones (significant at lower elevations), and snowmelt (dominant recharge process). The ecohydrologic model is also used to investigate how climatic and vegetative controls influence recharge dynamics within three elevation zones. The ecohydrologic model proves useful for investigating controls on recharge to mountain blocks as a function of climate and vegetation. Future efforts will need to investigate the uncertainty in the modeled water balance by incorporating an advanced understanding of mountain recharge processes, an ability to simulate those processes at varying scales, and independent approaches to calibrating MBR estimates. PMID:19702780

Magruder, Ian A; Woessner, William W; Running, Steve W

2009-01-01

319

Groundwater suitability recharge zones modelling - A GIS application  

NASA Astrophysics Data System (ADS)

Groundwater quality in Gujarat state is highly variable and due to multiplicity of factors viz. influenced by direct sea water encroachment, inherent sediment salinity, water logging, overexploitation leading to overall deterioration in ground water quality, coupled with domestic and industrial pollution etc. The groundwater scenario in the state is not very encouraging due to imbalance between recharge and groundwater exploitation. Further, the demand for water has increased manifold owing to agricultural, industrial and domestic requirement and this has led to water scarcity in many parts of the state, which is likely to become more severe in coming future due to both natural and manmade factors. Therefore, sustainable development of groundwater resource requires precise quantitative assessment based on reasonably valid scientific principles. Hence, delineation of groundwater potential zones (GWPZ), has acquired great significance. The present study focuses on the integrated Geospatial and Multi-Criteria Decision Making (MCDM) techniques to determine the most important contributing factors that affect the groundwater resources and also to delineate the potential zones for groundwater recharge. The multiple thematic layers of influencing parameters viz. geology, geomorphology, soil, slope, drainage density and land use, weightages were assigned to the each factor according to their relative importance as per subject experts opinion owing to the natural setup of the region. The Analytical Hierarchy Process (AHP) was applied to these factors and potential recharge zones were identified. The study area for the assessment of groundwater recharge potential zones is Mahi-Narmada inter-stream region of Gujarat state. The study shows that around 28 % region has the excellent suitability of the ground water recharge.

Dabral, S.; Bhatt, B.; Joshi, J. P.; Sharma, N.

2014-11-01

320

Defining Flood Recharge Processes: Lower Bill Williams River, Western Arizona  

NASA Astrophysics Data System (ADS)

River networks provide hydrologic connections between upland and headwater catchments and downstream reaches. In arid and semi-arid regions, full connectivity of a river system is rare and moments of connection may only occur during large flood events. Here we investigate the Bill Williams River, among the most arid river basins in the United States. The aridity of this system-and the associated lack of complicating hillslope processes adjacent to the river-provides a unique opportunity to study flood recharge processes in relative isolation. During all but the highest flows, the river infiltrates completely at the east end of Planet Valley and reemerges at the west end where it enters the Bill Williams River National Wildlife Refuge (NWR). Determining the source of baseflow in the lower Bill Williams/NWR, and the residence time of this water in the Planet Valley aquifer, will provide insight into the dependence of streamflow on earlier recharge-inducing floods. Defining this dependence more clearly is the next step toward a detailed knowledge of the long-term, basin-scale impacts of floods on water quality and quantity. To determine the impact of floods and the recharge they induce, surface and groundwater samples were collected during high and low flows throughout the basin from April 2007 through the present. Isotopic (?18OH2O, ?2HH2O) and chemical differences (most notably SO4) in streamflow and groundwater along the system indicate the importance of older groundwater in NWR baseflow-either in the form of prior flood recharge or influxes from local springs. Sulfate isotope analysis (?34SSO4, ?18OSO4) is pending for samples throughout the lower basin and this information should allow streamflow sources to be defined and quantified. This study provides a better characterization of the hydrologic and hydrochemical behavior of a Basin and Range river, and allows the effects of flood recharge processes to be more clearly defined at the basin scale.

Simpson, S. C.; Meixner, T.; Hogan, J.

2008-12-01

321

The simulation of the recharging method of active medical implant based on Monte Carlo method  

NASA Astrophysics Data System (ADS)

The recharging of Active Medical Implant (AMI) is an important issue for its future application. In this paper, a method for recharging active medical implant using wearable incoherent light source has been proposed. Firstly, the models of the recharging method are developed. Secondly, the recharging processes of the proposed method have been simulated by using Monte Carlo (MC) method. Finally, some important conclusions have been reached. The results indicate that the proposed method will help to result in a convenient, safe and low-cost recharging method of AMI, which will promote the application of this kind of implantable device.

Kong, Xianyue; Song, Yong; Hao, Qun; Cao, Jie; Zhang, Xiaoyu; Dai, Pantao; Li, Wansong

2014-11-01

322

Classification of ground-water recharge potential in three parts of Santa Cruz County, California  

USGS Publications Warehouse

Ground-water recharge potential was classified in the Santa Cruz coastal area, North-central area, and Soquel-Aptos area in Santa Cruz County, Calif., for three data elements that affect recharge; slope, soils, and geology. Separate numerical maps for each element were composited into a single numerical map using a classification system that ranked the numbers into areas of good , fair, and poor recharge potential. Most of the Santa Cruz coastal area and the Norht-central area have a poor recharge potential, and much of the Soquel-Aptos area has a good to fair recharge potential. (Kosco-USGS)

Muir, K.S.; Johnson, Michael J.

1979-01-01

323

Monitoring induced denitrification in an artificial aquifer recharge system.  

NASA Astrophysics Data System (ADS)

As demands on groundwater increase, artificial recharge is becoming a common method for enhancing groundwater supply. The Llobregat River is a strategic water supply resource to the Barcelona metropolitan area (Catalonia, NE Spain). Aquifer overexploitation has leaded to both a decrease of groundwater level and seawater intrusion, with the consequent deterioration of water quality. In the middle section of the aquifer, in Sant Vicenç del Horts, decantation and infiltration ponds recharged by water from the Llobregat River (highly affected from wastewater treatment plant effluents), were installed in 2007, in the framework of the ENSAT Life+ project. At the bottom of the infiltration pond, a vegetal compost layer was installed to promote the growth of bacteria, to induce denitrification and to create favourable conditions for contaminant biodegradation. This layer consists on a mixture of compost, aquifer material, clay and iron oxide. Understanding the fate of contaminants, such as nitrate, during artificial aquifer recharge is required to evaluate the impact of artificial recharge in groundwater quality. In order to distinguish the source of nitrate and to evaluate the capability of the organic reactive layer to induce denitrification, a multi-isotopic approach coupled with hydrogeochemical data was performed. Groundwater samples, as well as river samples, were sampled during artificial and natural recharge periods. The isotopic analysis included: ?15N and ?18O of dissolved nitrate, ?34S and ?18O of dissolved sulphate, ?13C of dissolved inorganic carbon, and ?2H and ?18O of water. Dissolved nitrate isotopic composition (?15NNO3 from +9 to +21 o and ?18ONO3 from +3 to +16 ) demonstrated that heterotrophic denitrification induced by the reactive layer was taking place during the artificial recharge periods. An approximation to the extent of nitrate attenuation was calculated, showing a range between 95 and 99% or between 35 and 45%, by using the extreme literature ?N values of -4o and -22o respectively (Aravena and Robertson, 1998; Pauwels et al., 2000). Ongoing denitrification batch experiments will allow us to determine the specific nitrogen and oxygen isotopic fractionation induced by the organic reactive layer, in order to estimate more precisely the extent of denitrification during artificial aquifer recharge. These results confirmed that the reactive layer induces denitrification in the recharge ponds area, proving the usefulness of an isotopic approach to characterize water quality improvement occurring during artificial aquifer recharge. References 1. Aravena, R., Robertson, W.D., 1998. Use of multiple isotope tracers to evaluate denitrification in ground water: Study of nitrate from a large-flux septic system plume. Ground Water, 36(6): 975-982. 2. Pauwels, H., J.C., Kloppmann, W., 2000. Denitrification and mixing in a schist aquifer: Influence on water chemistry and isotopes. Chemical Geology, 168(3-4): 307-324. Acknowledgment This study was supported by the projects CGL2011-29975-C04-01 from the Spanish Government, 2009SGR-00103 from the Catalan Government and ENPI/2011/280-008 from the European Commission. Please fill in your abstract text.

Grau-Martinez, Alba; Torrentó, Clara; Folch, Albert; Domènech, Cristina; Otero, Neus; Soler, Albert

2014-05-01

324

Transient, spatially-varied recharge for groundwater modeling  

NASA Astrophysics Data System (ADS)

This study is aimed at producing spatially and temporally varying groundwater recharge for transient groundwater modeling in a pilot watershed in the North Okanagan, Canada. The recharge modeling is undertaken by using a Richard's equation based finite element code (HYDRUS-1D) [Simunek et al., 2002], ArcGISTM [ESRI, 2011], ROSETTA [Schaap et al., 2001], in situ observations of soil temperature and soil moisture and a long term gridded climate data [Nielsen et al., 2010]. The public version of HYDUS-1D [Simunek et al., 2002] and another beta version with a detailed freezing and thawing module [Hansson et al., 2004] are first used to simulate soil temperature, snow pack and soil moisture over a one year experimental period. Statistical analysis of the results show both versions of HYDRUS-1D reproduce observed variables to the same degree. Correlation coefficients for soil temperature simulation were estimated at 0.9 and 0.8, at depths of 10 cm and 50 cm respectively; and for soil moisture, 0.8 and 0.6 at 10 cm and 50 cm respectively. This and other standard measures of model performance (root mean square error and average error) showed a promising performance of the HYDRUS-1D code in our pilot watershed. After evaluating model performance using field data and ROSETTA derived soil hydraulic parameters, the HYDRUS-1D code is coupled with ArcGISTM to produce spatially and temporally varying recharge maps throughout the Deep Creek watershed. Temporal and spatial analysis of 25 years daily recharge results at various representative points across the study watershed reveal significant temporal and spatial variations; average recharge estimated at 77.8 ± 50.8mm /year. This significant variation over the years, caused by antecedent soil moisture condition and climatic condition, illustrates the common flaw of assigning a constant percentage of precipitation throughout the simulation period. Groundwater recharge modeling has previously been attempted in the Okanagan Basin and other parts of Canada by using the HELP code. However, HELP has known limitations related with boundary conditions as well as spatial and temporal discretization options, and thus cannot simulate highly variable fluxes near boundaries. The limitations are even more pronounced in semi-arid areas like the Okanagan Basin where upward fluxes can be high, because HELP assumes that water below evaporative zone simply drains to the base of a soil column without accounting for upward fluxes. In addition to these limitations, previous studies that used HELP for recharge estimation, [Towes and Allen, 2009; Jyrkama and Sykes, 2007], did not attempt to verify model performance in their study area. The study here presents an integrated procedure that can help address some of these often neglected modelling challenges. The significance of the method in transient groundwater modeling is demonstrated by applying the spatially and temporally varying recharge boundary condition to a saturated zone groundwater model, MIKESHE [DHI, 2009a]. The water table simulated using this method is found to be within 0.6 m of the observed values, whereas the water levels estimated using uniform recharge boundary condition can fluctuate by as much as 1.6 m. Root mean square errors were estimated at 0.3 and 0.94 respectively.

Assefa, K.; Woodbury, A. D.

2012-12-01

325

Transient,spatially-varied recharge for groundwater modeling  

NASA Astrophysics Data System (ADS)

This study is aimed at producing spatially and temporally varying groundwater recharge for transient groundwater modeling in a pilot watershed in the North Okanagan, Canada. The recharge modeling is undertaken by using a Richard's equation based finite element code (HYDRUS-1D) [Simunek et al., 2002], ArcGISTM [ESRI, 2011], ROSETTA [Schaap et al., 2001], in situ observations of soil temperature and soil moisture and a long term gridded climate data [Nielsen et al., 2010]. The public version of HYDUS-1D [Simunek et al., 2002] and another beta version with a detailed freezing and thawing module [Hansson et al., 2004] are first used to simulate soil temperature, snow pack and soil moisture over a one year experimental period. Statistical analysis of the results show both versions of HYDRUS-1D reproduce observed variables to the same degree. Correlation coefficients for soil temperature simulation were estimated at 0.9 and 0.8, at depths of 10 cm and 50 cm respectively; and for soil moisture, 0.8 and 0.6 at 10 cm and 50 cm respectively. This and other standard measures of model performance (root mean square error and average error) showed a promising performance of the HYDRUS-1D code in our pilot watershed. After evaluating model performance using field data and ROSETTA derived soil hydraulic parameters, the HYDRUS-1D code is coupled with ArcGISTM to produce spatially and temporally varying recharge maps throughout the Deep Creek watershed. Temporal and spatial analysis of 25 years daily recharge results at various representative points across the study watershed reveal significant temporal and spatial variations; average recharge estimated at 77.8 ± 50.8mm /year. This significant variation over the years, caused by antecedent soil moisture condition and climatic condition, illustrates the common flaw of assigning a constant percentage of precipitation throughout the simulation period. Groundwater recharge modeling has previously been attempted in the Okanagan Basin and other parts of Canada by using the HELP code. However, HELP has known limitations related with boundary conditions as well as spatial and temporal discretization options, and thus cannot simulate highly variable fluxes near boundaries. The limitations are even more pronounced in semi-arid areas like the Okanagan Basin where upward fluxes can be high, because HELP assumes that water below evaporative zone simply drains to the base of a soil column without accounting for upward fluxes. In addition to these limitations, previous studies that used HELP for recharge estimation, [Towes and Allen, 2009; Jyrkama and Sykes, 2007], did not attempt to verify model performance in their study area. The study here presents an integrated procedure that can help address some of these often neglected modelling challenges. The significance of the method in transient groundwater modeling is demonstrated by applying the spatially and temporally varying recharge boundary condition to a saturated zone groundwater model, MIKESHE [DHI, 2009a]. The water table simulated using this method is found to be within 0.6 m of the observed values, whereas the water levels estimated using uniform recharge boundary condition can fluctuate by as much as 1.6 m. Root mean square errors were estimated at 0.3 and 0.94 respectively.

Assefa, Kibreab; Woodbury, Allan

2013-04-01

326

Hydrometeorological daily recharge assessment model (DREAM) for the Western Mountain Aquifer, Israel: Model application and effects of temporal patterns  

Microsoft Academic Search

Recharge is a critical issue for water management. Recharge assessment and the factors affecting recharge are of scientific and practical importance. The purpose of this study was to develop a daily recharge assessment model (DREAM) on the basis of a water balance principle with input from conventional and generally available precipitation and evaporation data and demonstrate the application of this

N. A. Sheffer; E. Dafny; H. Gvirtzman; S. Navon; A. Frumkin; E. Morin

2010-01-01

327

Combined estimation of specific yield and natural recharge in a semi-arid groundwater basin with irrigated agriculture  

Microsoft Academic Search

A water budget approach is developed to jointly estimate specific yield and natural recharge in an unconfined aquifer with significant seasonal water table fluctuations. Water table fluctuations are due to distinct seasonality in groundwater recharge. The separation of the hydrologic year into two (or more) extended seasons of recharge (wet season) and no-recharge (dry season) with accompanying changes in water

J. C. Maréchal; B. Dewandel; S. Ahmed; L. Galeazzi; F. K. Zaidi

2006-01-01

328

Reflectance of aqueous solutions  

NASA Technical Reports Server (NTRS)

The optical properties and optical constants of water and aqueous solutions were studied to develop an accurate tabulation of graphical representations of the optical constants through a broad spectrum. Manuscripts of articles are presented concerning extinction coefficients, relative specular reflectance, and temperature effect on the water spectrum. Graphs of absolute reflectance, phase shifts, index of refraction, and extinction coefficients for water, heavy water and aqueous solutions are included.

Querry, M. R.

1972-01-01

329

Geophysical Methods for Improved Understanding of Managed Aquifer Recharge (Invited)  

NASA Astrophysics Data System (ADS)

Managed aquifer recharge is increasingly being used as a means of augmenting groundwater supplies. With the increased use, questions arise regarding the suitability of sites for such operations, as well as the operational efficiency of these systems. In this work we specifically look at MAR using an artificial recharge pond. There are two operational challenges commonly faced in artificial recharge ponds: 1) A decrease in infiltration rate of water into the subsurface during operating; this limits the amount of stored water. 2) Low recovery rates of the stored water. Addressing both of these challenges requires sufficient information about the spatial and temporal variation in governing hydrologic properties and processes. Geophysical methods provide a novel way of obtaining such information from the region beneath a recharge pond. A study of the Harkins Slough Recharge Pond, near Watsonville California, presented a unique opportunity to develop and test geophysical methods, specifically for improved understanding off MAR. At this site we deployed a series of geophysical sensors aimed at addressing the two operational challenges at the site. We first addressed the question: What is controlling the decrease in filtration rate? The development and installation of electrical conductivity probes beneath the pond allowed us to monitor changes in the top ~1 m over a 4-month period. This dataset revealed that clogging in the top ~10 cm was responsible for the decreased infiltration rate. These 1D data were augmented by a time-lapse 2D ERT dataset that shows significant lateral variability in infiltration at the site. The second question we addressed was: Why is the recovery rate so low? Using a combination of cone-penetrometer testing and seismic reflection data, we developed a subsurface model that suggested there was a thin clay layer that may be impeding the flow of water to the recovery wells. To further understand this, we developed electrical conductivity probes, containing pore pressure transducers, to monitor changes in electrical conductivity and fluid pressure to a depth of 30 m. The data acquired with these probes clearly showed that the subsurface clay layer was impeding flow to the screened zone of the recovery wells. The findings at the site demonstrate the value of geophysics obtaining information regarding the siting and operation of artificial recharge ponds.

Pidlisecky, A.; Nenna, V.; Knight, R. J.

2013-12-01

330

Recharging behavior of nitrogen-centers in ZnO  

SciTech Connect

Electron Paramagnetic Resonance was used to study N{sub 2}-centers in ZnO, which show a 5-line spectrum described by the hyperfine interaction of two nitrogen nuclei (nuclear spin I?=?1, 99.6% abundance). The recharging of this center exhibits two steps, a weak onset at about 1.4?eV and a strongly increasing signal for photon energies above 1.9?eV. The latter energy coincides with the recharging energy of N{sub O} centers (substitutional nitrogen atoms on oxygen sites). The results indicate that the N{sub 2}-centers are deep level defects and therefore not suitable to cause significant hole-conductivity at room temperature.

Philipps, Jan M., E-mail: jan.m.philipps@physik.uni-giessen.de; Meyer, Bruno K.; Hofmann, Detlev M. [I. Physikalisches Institut, Justus-Liebig-Universitaet Giessen, D-35392 Giessen (Germany); Stehr, Jan E.; Buyanova, Irina [Department of Physics, Chemistry and Biology, Linkoeping University, 58183 Linkoeping (Sweden); Tarun, Marianne C.; McCluskey, Matthew D. [Department of Physics and Astronomy and Materials Science Program, Washington State University, Pullman, Washington 99164-2814 (United States)

2014-08-14

331

Evaluating storm-scale groundwater recharge dynamics with coupled weather radar data and unsaturated zone modeling  

NASA Astrophysics Data System (ADS)

Groundwater recharge rates through the unsaturated zone emerge from complex interactions within the soil-vegetation-atmosphere system that derive from nonlinear relationships amongst atmospheric boundary conditions, plant water use and soil hydraulic properties. While it is widely recognized that hydrologic models must capture soil water dynamics in order to provide reliable recharge estimates, information on episodic recharge generation remains uncommon, and links between storm-scale weather patterns and their influence on recharge is largely unexplored. In this study, the water balance of a heterogeneous one-dimensional soil domain (3 m deep) beneath a typical rainfed corn agro-ecosystem in eastern Nebraska was numerically simulated in HYDRUS-1D for 12 years (2001-2012) on hourly time steps in order to assess the relationships between weather events and episodic recharge generation. WSR-88D weather radar reflectivity data provided both rainfall forcing data (after estimating rain rates using the z/r ratio method) and a means of storm classification on a scale from convective to stratiform using storm boundary characteristics. Individual storm event importance to cumulative recharge generation was assessed through iterative scenario modeling (773 total simulations). Annual cumulative recharge had a mean value of 9.19 cm/yr (about 12 % of cumulative rainfall) with coefficient of variation of 73%. Simulated recharge generation events occurred only in late winter and spring, with a peak in May (about 35% of total annual recharge). Recharge generation is observed primarily in late spring and early summer because of the combination of high residual soil moisture following a winter replenishment period, heavy convective storms, and low to moderate potential evapotranspiration rates. During the growing season, high rates of root water uptake cause rapid soil water depletion, and the concurrent high potential evapotranspiration and low soil moisture prevented recharge generation until late winter, even when intense convective storms took place. For this reason, about 86% of all precipitation events produce insignificant recharge contributions. Recharge responses to individual storms were nonlinear and did not cluster well with either storm amount or storm classification type. For example, ~7% of rainfall events fall near the 1:1 rainfall/recharge line and these events represent about 37% of cumulative recharge, and individual storms accounted for up to 4% of their annual totals. However, recharge events in late winter are mainly triggered by stratiform precipitation whereas in spring they are generally generated by convective storms. This novel approach to assessing storm-scale recharge may be relevant to several current challenges in the characterization of groundwater recharge processes, including the evaluation of their spatiotemporal distributions and the impacts of climate change on groundwater.

Nasta, P.; Gates, J. B.; Lock, N.; Houston, A. L.

2013-12-01

332

Advanced materials for electrodes and electrolyte in rechargeable lithium batteries  

Microsoft Academic Search

The lithium-ion (Li-ion) battery possesses many outstanding advantages over the well known rechargeable battery systems, in particularly higher energy density and longer shelf life, as well as not suffering from the memory effect problems of Ni-MH batteries. Those advantages are making it the greatest energy source of choice for the portable electronic market. Graphite and LiCoO2 are commonly used in

Sau yen Chew

2009-01-01

333

Recharging the Silicon Crucible in a Hot Furnace  

NASA Technical Reports Server (NTRS)

"Melt recharger" adds raw silicon to crucible in crystal-growing furnace without disturbing inert-gas atmosphere or significantly lowering temperature of melt. Crucible-refill hopper is lowered into hot zone of crystal-pulling chamber through an isolation valve. Cable that supports hopper is fastened to cone-shaped stopper in bottom of hopper. Stopper moves out of opening in hopper, allowing part of polysilicon charge to drop into crucible.

Lane, R. L.

1982-01-01

334

Scale effects of hydrostratigraphy and recharge zonation on base flow.  

PubMed

Uncertainty regarding spatial variations of model parameters often results in the simplifying assumption that parameters are spatially uniform. However, spatial variability may be important in resource assessment and model calibration. In this paper, a methodology is presented for estimating a critical basin size, above which base flows appear to be relatively less sensitive to the spatial distribution of recharge and hydraulic conductivity, and below which base flows are relatively more sensitive to this spatial variability. Application of the method is illustrated for a watershed that exhibits distinct infiltration patterns and hydrostratigraphic layering. A ground water flow model (MODFLOW) and a parameter estimation code (UCODE) were used to evaluate the influence of recharge zonation and hydrostratigraphic layering on base flow distribution. Optimization after removing spatial recharge variability from the calibrated model altered base flow simulations up to 53% in watersheds smaller than 40 km(2). Merging six hydrostratigraphic units into one unit with average properties increased base flow residuals up to 83% in basins smaller than 50 km(2). Base flow residuals changed <5% in watersheds larger than 40 and 50 km(2) when recharge and hydrostratigraphy were simplified, respectively; thus, the critical basin size for the example area is approximately 40 to 50 km(2). Once identified for an area, a critical basin size could be used to guide the scale of future investigations. By ensuring that parameter discretization needed to capture base flow distribution is commensurate with the scope of the investigation, uncertainty caused by overextending uniform parameterization or by estimating extra parameter values is reduced. PMID:16681517

Juckem, Paul F; Hunt, Randall J; Anderson, Mary P

2006-01-01

335

Spatial and temporal infiltration dynamics during managed aquifer recharge.  

PubMed

Natural groundwater recharge is inherently difficult to quantify and predict, largely because it comprises a series of processes that are spatially distributed and temporally variable. Infiltration ponds used for managed aquifer recharge (MAR) provide an opportunity to quantify recharge processes across multiple scales under semi-controlled conditions. We instrumented a 3-ha MAR infiltration pond to measure and compare infiltration patterns determined using whole-pond and point-specific methods. Whole-pond infiltration was determined by closing a transient water budget (accounting for inputs, outputs, and changes in storage), whereas point-specific infiltration rates were determined using heat as a tracer and time series analysis at eight locations in the base of the pond. Whole-pond infiltration, normalized for wetted area, rose rapidly to more than 1.0 m/d at the start of MAR operations (increasing as pond stage rose), was sustained at high rates for the next 40 d, and then decreased to less than 0.1 m/d by the end of the recharge season. Point-specific infiltration rates indicated high spatial and temporal variability, with the mean of measured values generally being lower than rates indicated by whole-pond calculations. Colocated measurements of head gradients within saturated soils below the pond were combined with infiltration rates to calculate soil hydraulic conductivity. Observations indicate a brief period of increasing saturated hydraulic conductivity, followed by a decrease of one to two orders of magnitude during the next 50 to 75 d. Locations indicating the most rapid infiltration shifted laterally during MAR operation, and we suggest that infiltration may function as a "variable source area" processes, conceptually similar to catchment runoff. PMID:22050208

Racz, Andrew J; Fisher, Andrew T; Schmidt, Calla M; Lockwood, Brian S; Los Huertos, Marc

2012-01-01

336

Managed aquifer recharge: rediscovering nature as a leading edge technology.  

PubMed

Use of Managed Aquifer Recharge (MAR) has rapidly increased in Australia, USA, and Europe in recent years as an efficient means of recycling stormwater or treated sewage effluent for non-potable and indirect potable reuse in urban and rural areas. Yet aquifers have been relied on knowingly for water storage and unwittingly for water treatment for millennia. Hence if 'leading edge' is defined as 'the foremost part of a trend; a vanguard', it would be misleading to claim managed aquifer recharge as a leading edge technology. However it has taken a significant investment in scientific research in recent years to demonstrate the effectiveness of aquifers as sustainable treatment systems to enable managed aquifer recharge to be recognised along side engineered treatment systems in water recycling. It is a 'cross-over' technology that is applicable to water and wastewater treatment and makes use of passive low energy processes to spectacularly reduce the energy requirements for water supply. It is robust within limits, has low cost, is suitable from village to city scale supplies, and offers as yet almost untapped opportunities for producing safe drinking water supplies where they do not yet exist. It will have an increasingly valued role in securing water supplies to sustain cities affected by climate change and population growth. However it is not a universal panacea and relies on the presence of suitable aquifers and sources of water together with effective governance to ensure human health and environment protection and water resources planning and management. This paper describes managed aquifer recharge, illustrates its use in Australia, outlining economics, guidelines and policies, and presents some of the knowledge about aquifer treatment processes that are revealing the latent value of aquifers as urban water infrastructure and provide a driver to improving our understanding of urban hydrogeology. PMID:21076220

Dillon, P; Toze, S; Page, D; Vanderzalm, J; Bekele, E; Sidhu, J; Rinck-Pfeiffer, S

2010-01-01

337

Changes in vegetation diversity caused by artificial recharge  

USGS Publications Warehouse

Efforst to increase the rate of artificial recharge through basins often necessitates scrapping and ditching before and during operations. Such operations can result in more or less drastic changes in vegetation (depending on what was there before), characterized by diminisched numbers of species and lowered diversity. Two examples, one from Texas and one from the Netherlands are presented showing how similar treatments cause similar changes in two completely difference plant communities. ?? 1979 Dr. W. Junk b.v. - Publishers.

Van Hylckama, T. E. A.

1979-01-01

338

Electrochemically Stable Cathode Current Collectors for Rechargeable Magnesium Batteries  

SciTech Connect

Rechargeable Mg batteries are attractive energy storage systems and could bring cost-effective energy solutions. Currently, however, no practical cathode current collectors that can withstand high voltages in Mg2+ electrolytes has been identified and therefore cathode research is greatly hindered. Here we identified that two metals, Mo and W, are electrochemically stable through formation of surface passive layers. The presented results could have significant impacts on the developments of high voltage Mg batteries.

Cheng, Yingwen; Liu, Tianbiao L.; Shao, Yuyan; Engelhard, Mark H.; Liu, Jun; Li, Guosheng

2014-01-01

339

The MOLICEL(R) rechargeable lithium system: Multicell battery aspects  

NASA Technical Reports Server (NTRS)

MOLICEL rechargeable lithium cells were cycled in batteries using series, parallel, and series/parallel connections. The individual cell voltages and branch currents were measured to understand the cell interactions. The observations were interpreted in terms of the inherent characteristics of the Li/MoS2 system and in terms of a singular cell failure mode. The results confirm that correctly configured multicell batteries using MOLICELs have performance characteristics comparable to those of single cells.

Fouchard, D.; Taylor, J. B.

1987-01-01

340

Estimating areas contributing recharge to wells, lessons from previous studies  

USGS Publications Warehouse

Factors relating to the estimation of areas contributing recharge to wells, such as complexity of the ground-water flow system, effects of changing hydrologic conditions, and effects of well-screen locations and pumping rates, are reviewed. The point of view that simulation is the best means to obtain physically based estimates of contributing areas is emphasized. An extensive list of USGS reports that include estimation of contributing areas is provided.

Franke, O. Lehn; Reilly, T.E.; Pollock, D.W.; LaBaugh, J.W.

1998-01-01

341

Estimating recharge at Yucca Mountain, Nevada: A case study  

SciTech Connect

Obtaining values of net infiltration, groundwater travel time, and recharge is necessary at the Yucca Mountain site, Nevada, USA, in order to evaluate the expected performance of a potential repository as a containment system for high-level radioactive waste. However, the geologic complexities of this site, its low precipitation and net infiltration, with numerous mechanisms operating simultaneously to move water through the system, provide many challenges for the estimation of the spatial distribution of recharge. A variety of methods appropriate for arid environments has been applied, including water-balance techniques, calculations using Darcy's law in the unsaturated zone, a soil-physics method applied to neutron-hole water-content data, inverse modeling of thermal profiles in boreholes extending through the thick unsaturated zone, chloride mass balance, atmospheric radionuclides, and empirical approaches. These methods indicate that near-surface infiltration rates at Yucca Mountain are highly variable in time and space, with local (point) values ranging from zero to several hundred millimeters per year. Spatially distributed net-infiltration values average 5 mm/year, with the highest values approaching 20 mm/year near Yucca Crest. Site-scale recharge estimates range from less than 1 to about 12 mm/year. These results have been incorporated into a site-scale model that has been calibrated using these data sets that reflect infiltration processes acting on highly variable temporal and spatial scales. The modeling study predicts highly non-uniform recharge at the water table, distributed significantly differently from the non-uniform infiltration pattern at the surface.

Flint, A.; Flint, L.; Kwicklis, E.; Fabryka-Martin, J.; Bodvarsson, G.S.

2001-05-13

342

Estimating recharge at yucca mountain, nevada, usa: comparison of methods  

SciTech Connect

Obtaining values of net infiltration, groundwater travel time, and recharge is necessary at the Yucca Mountain site, Nevada, USA, in order to evaluate the expected performance of a potential repository as a containment system for high-level radioactive waste. However, the geologic complexities of this site, its low precipitation and net infiltration, with numerous mechanisms operating simultaneously to move water through the system, provide many challenges for the estimation of the spatial distribution of recharge. A variety of methods appropriate for and environments has been applied, including water-balance techniques, calculations using Darcy's law in the unsaturated zone, a soil-physics method applied to neutron-hole water-content data, inverse modeling of thermal profiles in boreholes extending through the thick unsaturated zone, chloride mass balance, atmospheric radionuclides, and empirical approaches. These methods indicate that near-surface infiltration rates at Yucca Mountain are highly variable in time and space, with local (point) values ranging from zero to several hundred millimeters per year. Spatially distributed net-infiltration values average 5 mm/year, with the highest values approaching 20 nun/year near Yucca Crest. Site-scale recharge estimates range from less than I to about 12 mm/year. These results have been incorporated into a site-scale model that has been calibrated using these data sets that reflect infiltration processes acting on highly variable temporal and spatial scales. The modeling study predicts highly non-uniform recharge at the water table, distributed significantly differently from the non-uniform infiltration pattern at the surface. [References: 57

Flint, A. L.; Flint, L. E.; Kwicklis, E. M.; Fabryka-Martin, J. T.; Bodvarsson, G. S.

2001-11-01

343

Polymer Considerations in Rechargeable Lithium Ion Plastic Batteries  

Microsoft Academic Search

A series of polymers have been investigated in order to determine their suitability as ionically conductive binders of the active electrode materials and as hybrid electrolyte matrices in plastic lithium ion rechargeable batteries. Hybrid electrolyte films used in this study have been prepared by solvent casting using a 1:1 w\\/w mixture of the matrix polymer with 1 M LiPF6 in

Antoni S. Gozdz; Jean-Marie Tarascon; Caroline N. Schmutz; Paul Warren; O. S. Gebizlioglu; F. Shokoohi

1995-01-01

344

NiF2 Cathodes For Rechargeable Na Batteries  

NASA Technical Reports Server (NTRS)

Use of NiF2 cathodes in medium-to-high-temperature rechargeable sodium batteries increases energy and power densities by 25 to 30 percent without detracting from potential advantage of safety this type of sodium battery offers over sodium batteries having sulfur cathodes. High-energy-density sodium batteries with metal fluoride cathodes used in electric vehicles and for leveling loads on powerlines.

Bugga, Ratnakumar V.; Distefano, Salvador; Halpert, Gerald

1992-01-01

345

Evaluation of Recharge Potential at Crater U5a (WISHBONE)  

SciTech Connect

Radionuclides are present both below and above the water table at the Nevada Test Site (NTS), as the result of underground nuclear testing. Mobilization and transport of radionuclides from the vadose zone is a complex process that is influenced by the solubility and sorption characteristics of the individual radionuclides, as well as the soil water flux. On the NTS, subsidence craters resulting from testing underground nuclear weapons are numerous, and many intercept surface water flows. Because craters collect surface water above the sub-surface point of device detonation, these craters may provide a mechanism for surface water to recharge the groundwater aquifer system underlying the NTS. Given this situation, there is a potential for the captured water to introduce contaminants into the groundwater system. Crater U5a (WISHBONE), located in Frenchman Flat, was selected for study because of its potentially large drainage area, and significant erosional features, which suggested that it has captured more runoff than other craters in the Frenchman Flat area. Recharge conditions were studied in subsidence crater U5a by first drilling boreholes and analyzing the collected soil cores to determine the soil properties and moisture conditions. This information, coupled with a 32-year precipitation record, was used to conduct surface and vaodse zone modeling. Surface water modeling predicted that approximately 13 ponding events had occurred during the life of the crater. Vadose zone modeling indicated that since the crater's formation approximately 5,900 m3 of water were captured by the crater. Of this total, approximately 5,200 m3 of potential recahrge may have occurred, and the best estimates of annual average potential recharge rates lie between 36 and 188 cm of water per year. The term potential is used here to indicate that the water is not technically recharged because it has not yet reached the water table.

Richard H. French; Samuel L. Hokett

1998-11-01

346

Estimating recharge at Yucca Mountain, Nevada, USA: Comparison of methods  

USGS Publications Warehouse

Obtaining values of net infiltration, groundwater travel time, and recharge is necessary at the Yucca Mountain site, Nevada, USA, in order to evaluate the expected performance of a potential repository as a containment system for high-level radioactive waste. However, the geologic complexities of this site, its low precipitation and net infiltration, with numerous mechanisms operating simultaneously to move water through the system, provide many challenges for the estimation of the spatial distribution of recharge. A variety of methods appropriate for arid environments has been applied, including water-balance techniques, calculations using Darcy's law in the unsaturated zone, a soil-physics method applied to neutron-hole water-content data, inverse modeling of thermal profiles in boreholes extending through the thick unsaturated zone, chloride mass balance, atmospheric radionuclides, and empirical approaches. These methods indicate that near-surface infiltration rates at Yucca Mountain are highly variable in time and space, with local (point) values ranging from zero to several hundred millimeters per year. Spatially distributed net-infiltration values average 5 mm/year, with the highest values approaching 20 mm/year near Yucca Crest. Site-scale recharge estimates range from less than 1 to about 12 mm/year. These results have been incorporated into a site-scale model that has been calibrated using these data sets that reflect infiltration processes acting on highly variable temporal and spatial scales. The modeling study predicts highly non-uniform recharge at the water table, distributed significantly differently from the non-uniform infiltration pattern at the surface.

Flint, A.L.; Flint, L.E.; Kwicklis, E.M.; Fabryka-Martin, J. T.; Bodvarsson, G.S.

2002-01-01

347

Estimating recharge at Yucca Mountain, Nevada, USA: comparison of methods  

Microsoft Academic Search

.   Obtaining values of net infiltration, groundwater travel time, and recharge is necessary at the Yucca Mountain site, Nevada,\\u000a USA, in order to evaluate the expected performance of a potential repository as a containment system for high-level radioactive\\u000a waste. However, the geologic complexities of this site, its low precipitation and net infiltration, with numerous mechanisms\\u000a operating simultaneously to move water

Alan L. Flint; Lorraine E. Flint; Edward M. Kwicklis; June T. Fabryka-Martin; Gudmundur S. Bodvarsson

2002-01-01

348

Molten Air -- A new, highest energy class of rechargeable batteries  

E-print Network

This study introduces the principles of a new class of batteries, rechargeable molten air batteries, and several battery chemistry examples are demonstrated. The new battery class uses a molten electrolyte, are quasi reversible, and have amongst the highest intrinsic battery electric energy storage capacities. Three examples of the new batteries are demonstrated. These are the iron, carbon and VB2 molten air batteries with respective intrinsic volumetric energy capacities of 10,000, 19,000 and 27,000 Wh per liter.

Licht, Stuart

2013-01-01

349

A polyaniline and Nafion ® composite film as a rechargeable battery  

Microsoft Academic Search

The charge-discharge characteristics of polyaniline (PAn)-Nafion®-PAn composite films used as rechargeable batteries were investigated. The batteries were formed chemically by sandwiching Nafion® between two thin layers of PAn-Nafion® composite in equilibrium with various electrolytes. It was found that cells with LiClO4 in propylene carbonate as electrolyte showed the highest capacity. The charge and discharge performance of the battery was almost

N. Li; J. Y. Lee; L. H. Ong

1992-01-01

350

Development efforts in rechargeable batteries for underwater vehicles  

Microsoft Academic Search

For over two decades the White Oak Laboratory of the Naval Surface Warfare Center (NSWC) has been collaborating with the battery industry to develop advanced rechargeable batteries for underwater vehicles. Many underwater vehicles use zinc\\/silver oxide (Zn\\/AgO) batteries to supply the required propulsion power. Although Zn\\/AgO offers the highest energy density (55 watt hours per pound, Wh\\/lb) of any commercial

Patricia H. Smith; Stanley D. James; Peter B. Keller

1996-01-01

351

Estimation of groundwater recharge parameters by time series analysis.  

USGS Publications Warehouse

A model is proposed that relates water level fluctuations in a Dupuit aquifer to effective precipitation at the top of the unsaturated zone. Effective precipitation, defined herein as that portion of precipitation which becomes recharge, is related to precipitation measured in a nearby gage by a two-parameter function. A second-order stationary assumption is used to connect the spectra of effective precipitation and water level fluctuations.-from Authors

Naff, R.L.; Gutjahr, A.L.

1983-01-01

352

Natural recharge and localization of fresh ground water in Kuwait  

USGS Publications Warehouse

Fresh ground water (200 parts per million total dissolved solids and upwards) occurs in portions of Pleistocene sandstone aquifers beneath basins and wadis in north Kuwait where the mean rainfall is about five inches per year. The fresh water is surrounded and underlain by brackish water (> 4000 ppm TDS). Drilling and testing show that fresh water saturation is restricted to wadis and basin areas; in Rawdatain basin it attains a maximum thickness of about 110 feet and a lateral extent of about seven miles. The fresh ground water represents recharge localized, during infrequent, torrential rain storms, in areas of concentrated runoff where sediments in the vadose zone are moderately permeable and depth to the water table is generally less than a hundred feet. Concentration of runoff appears to be the primary control in the localization of recharge. The fresh water percolates downward to the ground-water reservoir following rare storms, then flows in the direction of hydraulic gradient and gradually becomes brackish. Theoretical delineation of the recharge area and ground-water flow pattern in Rawdatain was confirmed by tritium and C14 dating of the water. Brackish ground-water conditions prevail from water table downward in areas where rainfall infiltrates essentially where it falls, permeability of sediments in the vadose zone is low, or the water table is several hundred feet below land surface. In these areas, rainfall is retained and lost within the soil zone or becomes mineralized during deep percolation. ?? 1964.

Bergstrom, R.E.; Aten, R.E.

1965-01-01

353

A new analytical method for groundwater recharge and discharge estimation  

NASA Astrophysics Data System (ADS)

SummaryA new analytical method was proposed for groundwater recharge and discharge estimation in an unconfined aquifer. The method is based on an analytical solution to the Boussinesq equation linearized in terms of h2, where h is the water table elevation, with a time-dependent source term. The solution derived was validated with numerical simulation and was shown to be a better approximation than an existing solution to the Boussinesq equation linearized in terms of h. By calibrating against the observed water levels in a monitoring well during a period of 100 days, we shown that the method proposed in this study can be used to estimate daily recharge (R) and evapotranspiration (ET) as well as the lateral drainage. It was shown that the total R was reasonably estimated with a water-table fluctuation (WTF) method if the water table measurements away from a fixed-head boundary were used, but the total ET was overestimated and the total net recharge was underestimated because of the lack of consideration of lateral drainage and aquifer storage in the WTF method.

Liang, Xiuyu; Zhang, You-Kuan

2012-07-01

354

Preferential eruption of andesitic magmas through recharge filtering  

NASA Astrophysics Data System (ADS)

Andesitic volcanic rocks are common in subduction zones and are argued to play an important role in the formation and evolution of the continental crust at convergent margins. Andesite formation is dominated by mixing between iron- and magnesium-rich (mafic) magmas and silica-rich (felsic) magmas. The abundance of andesites in many subduction zones suggests they erupt in preference to the magmas that mix to produce them; however, the reasons for this remain unclear. Here we use textural and geochemical analyses of andesites from Mount Hood, Oregon, to show that eruptions are closely linked with episodes of mafic recharge-the intrusion of mafic magma into a shallow felsic magma reservoir. The felsic and mafic magmas involved rarely erupt by themselves, probably because the former are too viscous and the latter too dense. Mafic recharge overcomes these barriers to eruption, and, as it also promotes efficient mixing, results in preferential eruption of mixed andesitic magmas. The abundance of andesites therefore relates to local crustal conditions and the ability of magmas to erupt. We suggest that volcanoes, such as Mount Hood, that erupt homogeneous andesitic compositions through time are those that are the most reliant on mafic recharge to initiate eruptions.

Kent, Adam J. R.; Darr, Cristina; Koleszar, Alison M.; Salisbury, Morgan J.; Cooper, Kari M.

2010-09-01

355

Rheology of aqueous foams  

NASA Astrophysics Data System (ADS)

Aqueous foams are suspensions of bubbles inside aqueous phases. Their multiphasic composition leads to a complex rheological behavior that is useful in numerous applications, from oil recovery to food/cosmetic processing. Their structure is very similar to the one of emulsions, so that both materials share common mechanical properties. In particular, the presence of surfactants at the gas-liquid interfaces leads to peculiar interfacial and dissipative properties. Foam rheology has been an active research topics and is already reported in several reviews, most of them covering rheometry measurements at the scale of the foam, coupled with interpretations at the local scale of bubbles or interfaces. In this review, we start following this approach, then we try to cover the multiscale features of aqueous foam flows, emphasizing regimes where intermediate length scales need to be taken into account or regimes fast enough regarding internal time scales so that the flow goes beyond the quasi-static limit. xml:lang="fr"

Dollet, Benjamin; Raufaste, Christophe

2014-10-01

356

Ponds and Rice Fields: The Hydrology and Chemistry of Aquifer Recharge in Bangladesh  

NASA Astrophysics Data System (ADS)

The shallow aquifer in Bangladesh, which provides drinking water for millions and irrigation water for innumerable rice fields, is severely contaminated with naturally occurring arsenic. Water balance calculations show that surface ponds and irrigated rice fields are the primary sources of recharge to this contaminated aquifer. Recharge from an individual rice field is both temporally and spatially heterogeneous, whereas flow from a pond is more constant and uniform through the pond sediments. Rice field recharge is focused through bunds (the berms surrounding the field), and depends on irrigation intervals. Field flow patterns are controlled by cracks and the development of an unsaturated zone. The water chemistry of these two recharge sources is distinctly different. Compared to the rice fields, ponds contribute recharge with a higher organic carbon load and increased concentrations of solutes associated with anoxic microbial respiration. The differences in the recharge behavior and solute loads of these two sources may explain the spatial patterns of groundwater chemistry that control arsenic concentrations.

Neumann, R. B.; Harvey, C. F.

2007-12-01

357

Ground-water recharge through active sand dunes in northwestern Nevada  

USGS Publications Warehouse

Most water-resource investigations in semiarid basins of the Great Basin in western North America conclude that ground-water recharge from direct precipitation on the valley floor is negligible. However, many of these basins contain large areas covered by unvegetated, active sand dunes that may act as conduits for ground-water recharge. The potential for this previously undocumented recharge was investigated in an area covered by sand dunes in Desert Valley, northwestern Nevada, using a deep percolation model. The model uses daily measurements of precipitation and temperature to determine energy and moisture balance, from which estimates of long-term mean annual recharge are made. For the study area, the model calculated a mean annual recharge rate of as much as 1.3 inches per year, or 17 percent of the long-term mean precipitation. Model simulations also indicate that recharge would be virtually zero if the study area were covered by vegetation rather than dunes.

Berger, D.L.

1992-01-01

358

Effects of Microtopographically Concentrated Recharge on Nitrate Variability in a Confined Aquifer: Model Simulations  

Microsoft Academic Search

Simulated recharge to a shallow confined aquifer indicates that locally concentrated recharge through microtopographically determined recharge areas (having elevation differences of less than 2 cm) can have a substantial effect on the spatial variability of nitrate-N concentrations [N-NO3] in the upper meter of an aquifer. For an aquifer that is confined and near pressure equilibrium with the watertable, hydraulic mounds

W. M. Schuh; D. L. Klinkebiel

2003-01-01

359

Shallow groundwater recharge mechanism and apparent age in the Ndop plain, northwest Cameroon  

NASA Astrophysics Data System (ADS)

Knowledge of groundwater recharge and apparent age constitutes a valuable tool for its sustainable management. Accordingly, shallow groundwater (n = 72) in the Ndop plain has been investigated using the stable isotopes of oxygen (18O) and hydrogen (2H or D) and tritium (3H) to determine the recharge process, timing and rate of recharge, and residence time. The shallow groundwater showed low variability in ?18O values (-2.7 to -4.1 ‰) and 3H content (2.4-3.1 TU). The low variability suggests a similar origin, homogenous aquifer, good water mixing and storage capacity of the groundwater reservoir. Like surface water, a cluster of groundwater along the Ndop Meteoric Water Line (NMWL) and Global Meteoric Water Line indicates meteoric origin/recharge. The rainfall recharge occurs under low relative humidity conditions and negligible evaporation effect. About 80 % of the recharge is from direct heterogeneous/diffuse local precipitation at low altitude (<1,260 m) within the Ndop plain. Approximately 20 % is from high altitude precipitation (localised recharge) or is recharged by the numerous inflowing streams and rivers from high elevations. A homogenous cluster of ?-values in groundwater (and surface water) between May and June monsoon rains on the NMWL suggests dominant recharge during these months. The recharge represents at least 16 % (>251 mm) of the annual rainfall (1,540 mm) indicating high annual recharge; high enough for development of the groundwater resource for agriculture. The 3H content (>2.4 TU) in groundwater indicates post-1952 recharged water with an estimated residence time <30 years, suggesting short subsurface circulation, and subsequently a renewable aquifer.

Wirmvem, Mengnjo Jude; Mimba, Mumbfu Ernestine; Kamtchueng, Brice Tchakam; Wotany, Engome Regina; Bafon, Tasin Godlove; Asaah, Asobo Nkengmatia Elvis; Fantong, Wilson Yetoh; Ayonghe, Samuel Ndonwi; Ohba, Takeshi

2015-02-01

360

Multi-component transport and transformation in deep confined aquifer during groundwater artificial recharge.  

PubMed

Taking an artificial groundwater recharge site in Shanghai, China as an example, this study employed a combination of laboratory experiment and numerical modeling to investigate the transport and transformation of major solutes, as well as the mechanism of associated water-rock interactions in groundwater during artificial groundwater recharge. The results revealed that: (1) Major ions in groundwater were mainly affected by mixing, ion exchanging (Ca(2+), Mg(2+), Na(+), K(+)), as well as dissolution of Calcite, Dolomite. Dissolution of carbonate minerals was not entirely dependent on the pattern of groundwater recharge, the reactivity of the source water itself as indicated by the sub-saturation with respect to the carbonate minerals is the primary factor. (2) Elemental dissolution of As, Cr and Fe occurred in aquifer was due to the transformation of subsurface environment from anaerobic to aerobic systems. Different to bank filtration recharge or pond recharge, the concentration of Fe near the recharge point was mainly controlled by oxidation dissolution of Siderite, which was followed by a release of As, Cr into groundwater. (3) Field modeling results revealed that the hydro chemical type of groundwater gradually changed from the initial Cl-HCO3-Na type to the Cl-HCO3-Na-Ca type during the recharge process, and its impact radius would reach roughly 800 m in one year. It indicated that the recharge pressure (approx. 0.45 Mpa) would enlarge the impact radius under deep well recharge conditions. According to different recharge modes, longer groundwater resident time will associate with minerals' fully reactions. Although the concentrations of major ions were changing during the artificial recharge process, it did not pose a negative impact on the environmental quality of groundwater. The result of trace elements indicated that controlling the environment factors (especially Eh, DO, flow rate) during the recharge was effective to reduce the potential threats to groundwater quality. PMID:25617875

Zhang, Wenjing; Huan, Ying; Yu, Xipeng; Liu, Dan; Zhou, Jingjing

2015-04-01

361

Using CRD method for quantification of groundwater recharge in the Gaza Strip, Palestine  

Microsoft Academic Search

Rainfall is the main source of groundwater recharge in the Gaza Strip area in Palestine. The area is located in the semi-arid\\u000a zone and there is no source of recharge other than rainfall. Estimation of groundwater recharge from rainfall is not an easy\\u000a task since it depends on many uncertain parameters. The cumulative rainfall departure (CRD) method, which depends on

Husam Baalousha

2005-01-01

362

Soil Water Balance and Recharge Monitoring at the Hanford Site - FY09 Status Report  

SciTech Connect

Recharge provides the primary driving force for transporting contaminants from the vadose zone to underlying aquifer systems. Quantification of recharge rates is important for assessing contaminant transport and fate and for evaluating remediation alternatives. This report describes the status of soil water balance and recharge monitoring performed by Pacific Northwest National Laboratory at the Hanford Site for Fiscal Year 2009. Previously reported data for Fiscal Years 2004 - 2008 are updated with data collected in Fiscal Year 2009 and summarized.

Rockhold, Mark L.; Saunders, Danielle L.; Strickland, Christopher E.; Waichler, Scott R.; Clayton, Ray E.

2009-09-28

363

Estimation of groundwater recharge from water storage structures in a semi-arid climate of India  

Microsoft Academic Search

Groundwater recharge from water storage structures under semi-arid conditions of western India has been estimated by employing water table fluctuation (WTF) and chloride mass balance (CMB) methods. Groundwater recharge was estimated as 7.3% and 9.7% of the annual rainfall by WTF method for the years 2003 and 2004, respectively while the two years average recharge was estimated as 7.5% using

V. N. Sharda; R. S. Kurothe; D. R. Sena; V. C. Pande; S. P. Tiwari

2006-01-01

364

Impacts of climate change on groundwater in Australia: a sensitivity analysis of recharge  

Microsoft Academic Search

Groundwater recharge is a complex process reflecting many interactions between climate, vegetation and soils. Climate change\\u000a will impact upon groundwater recharge but it is not clear which climate variables have the greatest influence over recharge.\\u000a This study used a sensitivity analysis of climate variables using a modified version of WAVES, a soil-vegetation-atmosphere-transfer\\u000a model (unsaturated zone), to determine the importance of

J. L. McCallum; R. S. Crosbie; G. R. Walker; W. R. Dawes

2010-01-01

365

Climatic controls on diffuse groundwater recharge in semiarid environments of the southwestern United States  

Microsoft Academic Search

Although there is no diffuse groundwater recharge at many semiarid sites, evidence for diffuse recharge exists at some locations where mean annual precipitation $\\\\overline{P}$ is much less than mean annual potential evapotranspiration $\\\\overline{PET}$, particularly where soils are coarse and rainfall variable is substantial. We investigate the climatic controls on diffuse recharge using a one-dimensional, variably saturated flow model. The model

Eric E. Small

2005-01-01

366

Synthesis and characterization of nanostructured cathode materials for rechargeable lithium/lithium ion batteries  

NASA Astrophysics Data System (ADS)

The rapidly increasing markets of portable electronic devices and electric/hybrid vehicles have raised worldwide R&D efforts in developing high-energy rechargeable lithium and lithium ion batteries. High performance intercalation cathodes are key to the success of these batteries. The nanotechnology has endowed the electrode materials with a variety of improved features as well as unique characteristics. Synthesis approaches were designed in this thesis work to utilize these advantages and investigate the exceptional phenomena raised by the nanostructured materials. A novel sol-gel method was designed for the synthesis of carbon-coated phase-pure lithium iron phosphate with submicron particle sizes and uniform size distribution. The surface carbon coating was formed in-situ through pyrolysis of the precursor gel, which improved the apparent electronic conductivity of the as prepared material to 10-2 S/cm compared with 10-9-10-10 S/cm of the pristine LiFePO 4. The favorable physical characteristics of the synthesized LiFePO 4 particles and the improved electronic conductivity through the carbon coating led to electrochemical properties comparable to the best performances reported so far. Amorphous manganese oxide cryogels with nanoarchitecture were obtained by freeze-drying Mn (IV) oxide hydrogels. The combination of the advantages of the amorphous structure and the nano-architecture of the materials gave high capacities and excellent rate capabilities. This work led to the finding of a nanocrystalline Li2MnO3-like compound with a surprising electrochemical activity, which is in sharp contrast to the microcrystalline rock-salt Li2MnO3 that has been known to be electrochemically inactive. The study highlights the possibility of qualitative difference in intercalation behavior of nanostructured intercalation compounds compared with their microcrystalline counterparts. Bismuth and copper modified amorphous manganese oxides were synthesized by aqueous coprecipitation methods and investigated as intercalation hosts for rechargeable lithium batteries. The results suggest the promise of achieving high performance intercalation electrodes by enhancing amorphous manganese oxides through cation modification.

Yang, Jingsi

367

Raising the cycling stability of aqueous lithium-ion batteries by eliminating oxygen in the electrolyte.  

PubMed

Aqueous lithium-ion batteries may solve the safety problem associated with lithium-ion batteries that use highly toxic and flammable organic solvents, and the poor cycling life associated with commercialized aqueous rechargeable batteries such as lead-acid and nickel-metal hydride systems. But all reported aqueous lithium-ion battery systems have shown poor stability: the capacity retention is typically less than 50% after 100 cycles. Here, the stability of electrode materials in an aqueous electrolyte was extensively analysed. The negative electrodes of aqueous lithium-ion batteries in a discharged state can react with water and oxygen, resulting in capacity fading upon cycling. By eliminating oxygen, adjusting the pH values of the electrolyte and using carbon-coated electrode materials, LiTi(2)(PO(4))(3)/Li(2)SO(4)/LiFePO(4) aqueous lithium-ion batteries exhibited excellent stability with capacity retention over 90% after 1,000 cycles when being fully charged/discharged in 10 minutes and 85% after 50 cycles even at a very low current rate of 8 hours for a full charge/discharge offering an energy storage system with high safety, low cost, long cycling life and appropriate energy density. PMID:20729897

Luo, Jia-Yan; Cui, Wang-Jun; He, Ping; Xia, Yong-Yao

2010-09-01

368

Groundwater recharge at five representative sites in the Hebei Plain, China.  

PubMed

Accurate estimates of groundwater recharge are essential for effective management of groundwater, especially when supplies are limited such as in many arid and semiarid areas. In the Hebei Plain, China, water shortage is increasingly restricting socioeconomic development, especially for agriculture, which heavily relies on groundwater. Human activities have greatly changed groundwater recharge there during the past several decades. To obtain better estimates of recharge in the plain, five representative sites were selected to investigate the effects of irrigation and water table depth on groundwater recharge. At each site, a one-dimensional unsaturated flow model (Hydrus-1D) was calibrated using field data of climate, soil moisture, and groundwater levels. A sensitivity analysis of evapotranspirative fluxes and various soil hydraulic parameters confirmed that fine-textured surface soils generally generate less recharge. Model calculations showed that recharge on average is about 175 mm/year in the piedmont plain to the west, and 133 mm/year in both the central alluvial and lacustrine plains and the coastal plain to the east. Temporal and spatial variations in the recharge processes were significant in response to rainfall and irrigation. Peak time-lags between infiltration (rainfall plus irrigation) and recharge were 18 to 35 days in the piedmont plain and 3 to 5 days in the central alluvial and lacustrine plains, but only 1 or 2 days in the coastal plain. This implies that different time-lags corresponding to different water table depths must be considered when estimating or modeling groundwater recharge. PMID:20100294

Lu, Xiaohui; Jin, Menggui; van Genuchten, Martinus Th; Wang, Bingguo

2011-01-01

369

Hydrological functions of sinkholes and characteristics of point recharge in groundwater basins  

NASA Astrophysics Data System (ADS)

Karstic limestone aquifers are hydrologically and hydrochemically extremely heterogeneous and point source recharge via sinkholes and fissures is a common feature. We studied three groundwater systems in karstic settings dominated by point source recharge in order to assess the relative contributions to total recharge from point sources using chloride and ?18O relations. Preferential groundwater flows were observed through an inter-connected network of highly conductive zones with groundwater mixing along flow paths. Measurements of salinity and chloride indicated that fresh water pockets exist at point recharge locations. A measurable fresh water plume develops only when a large quantity of surface water enters the aquifer as a point recharge source. The difference in chloride concentrations in diffuse and point recharge zones decreases as aquifer saturated thickness increases and the plumes become diluted through mixing. The chloride concentration in point recharge fluxes crossing the watertable plane can remain at or near surface runoff chloride concentrations, rather than in equilibrium with groundwater chloride. In such circumstances the conventional chloride mass balance method that assumes equilibrium of recharge water chloride with groundwater requires modification to include both point and diffuse recharge mechanisms.

Somaratne, N.; Smettem, K.; Lawson, J.; Nguyen, K.; Frizenschaf, J.

2013-09-01

370

Estimation of groundwater recharge from water storage structures in a semi-arid climate of India  

NASA Astrophysics Data System (ADS)

SummaryGroundwater recharge from water storage structures under semi-arid conditions of western India has been estimated by employing water table fluctuation (WTF) and chloride mass balance (CMB) methods. Groundwater recharge was estimated as 7.3% and 9.7% of the annual rainfall by WTF method for the years 2003 and 2004, respectively while the two years average recharge was estimated as 7.5% using CMB method. A Recharge function depicting the relationship between potential recharge from storage structures and successive day averaged storage depths was better exhibited by a power function. A diagnostic relationship correlating the rainfall to the potential recharge from water storage structures has been developed to explain the characteristics of the storage structures for a given geographical location. The study has revealed that a minimum of 104.3 mm cumulative rainfall is required to generate 1 mm of recharge from the water storage structures. It was also inferred that the storage structures have limited capacity to induce maximum recharge irrespective of the amount of rainfall and maximum recharge to rainfall ratio is achieved at a lower rainfall than the average annual rainfall of the area. An empirical linear relationship was found to reasonably correlate the changes in chloride concentration with water table rise or fall in the study area.

Sharda, V. N.; Kurothe, R. S.; Sena, D. R.; Pande, V. C.; Tiwari, S. P.

2006-09-01

371

A numerical analysis on the applicability of the water level fluctuation method for quantifying groundwater recharge  

NASA Astrophysics Data System (ADS)

The water table fluctuation(WTF) method is a conventional method for quantifying groundwater recharge by multiplying the specific yield to the water level rise. Based on the van Genuchten model, an analytical relationship between groundwater recharge and the water level rise is derived. The equation is used to analyze the effects of the depth to water level and the soil properties on the recharge estimate using the WTF method. The results show that the WTF method is reliable when applied to the aquifers of the fluvial sand provided the water table is below 1m depth. However, if it is applied to the silt loam having the water table depth ranging 4~10m, the recharge is overestimated by 30~80%, and the error increases drastically as the water table is getting shallower. A 2-D unconfined flow model with a time series of the recharge rate is developed. It is used for elucidating the errors of the WTF method, which is implicitly based on the tank model where the horizontal flow in the saturated zone is ignored. Simulations show that the recharge estimated by the WTF method is underestimated for the observation well near the discharge boundary. This is due to the fact that the hydraulic stress resulting from the recharge is rapidly dissipating by the horizontal flow near the discharge boundary. Simulations also reveal that the recharge is significantly underestimated with increase in the hydraulic conductivity and the recharge duration, and decrease in the specific yield.

Koo, M.; Lee, D.

2002-12-01

372

Modeling spatiotemporal impacts of hydroclimatic extremes on groundwater recharge at a Mediterranean karst aquifer  

NASA Astrophysics Data System (ADS)

Karst aquifers provide large parts of the water supply for Mediterranean countries, though climate change is expected to have a significant negative impact on water availability. Recharge is therefore a key variable that has to be known for sustainable groundwater use. In this study, we present a new approach that combines two independent methods for karst recharge estimation. The first method derives spatially distributed information of mean annual recharge patterns through GIS analysis. The second is a process-based karst model that provides spatially lumped but temporally distributed information about recharge. By combining both methods, we add a spatial reference to the lumped simulations of the process-based model. In this way, we are able to provide spatiotemporal information of recharge and subsurface flow dynamics also during varying hydroclimatic conditions. We find that there is a nonlinear relationship between precipitation and recharge rates resulting in strong decreases of recharge following even moderate decreases of precipitation. This is primarily due to almost constant actual evapotranspiration amounts despite varying hydroclimatic conditions. During the driest year in the record, almost the entire precipitation was consumed as actual evapotranspiration and only little diffuse recharge took place at the high altitudes of our study site. During wettest year, recharge constituted a much larger fraction of precipitation and occurred at the entire study site. Our new method and our findings are significant for decision makers in similar regions that want to prepare for possible changes of hydroclimatic conditions in the future.

Hartmann, Andreas; Mudarra, Matías; Andreo, Bartolomé; Marín, Ana; Wagener, Thorsten; Lange, Jens

2014-08-01

373

A generalized estimate of ground-water-recharge rates in the Lower Peninsula of Michigan  

USGS Publications Warehouse

Ground-water recharge rates were estimated by analysis of streamflow, precipitation, and basin-characteristics data. Streamflow data were partitioned into ground-water-discharge and surface-water-runoff components. Regression equations relate ground-water discharge to precipitation at each basin. Basin-characteristics and long-term precipitation data were used to aid in the interpolation of recharge characteristics within gaged and ungaged areas. A multiple regression equation was developed to estimate spatial variation of recharge. The generalized estimate provides a consistent method for approximating recharge rates in the Lower Peninsula of Michigan.

Holtschlag, David J.

1997-01-01

374

Use of soil moisture probes to estimate ground water recharge at an oil spill site  

USGS Publications Warehouse

Soil moisture data collected using an automated data logging system were used to estimate ground water recharge at a crude oil spill research site near Bemidji, Minnesota. Three different soil moisture probes were tested in the laboratory as well as the field conditions of limited power supply and extreme weather typical of northern Minnesota: a self-contained reflectometer probe, and two time domain reflectometry (TDR) probes, 30 and 50 cm long. Recharge was estimated using an unsaturated zone water balance method. Recharge estimates for 1999 using the laboratory calibrations were 13 to 30 percent greater than estimates based on the factory calibrations. Recharge indicated by the self-contained probes was 170 percent to 210 percent greater than the estimates for the TDR probes regardless of calibration method. Results indicate that the anomalously large recharge estimates for the self-contained probes are not the result of inaccurate measurements of volumetric moisture content, but result from the presence of crude oil, or bore-hole leakage. Of the probes tested, the 50 cm long TDR probe yielded recharge estimates that compared most favorably to estimates based on a method utilizing water table fluctuations. Recharge rates for this probe represented 24 to 27 percent of 1999 precipitation. Recharge based on the 30 cm long horizontal TDR probes was 29 to 37 percent of 1999 precipitation. By comparison, recharge based on the water table fluctuation method represented about 29 percent of precipitation. (JAWRA) (Copyright ?? 2005).

Delin, G.N.; Herkelrath, W.N.

2005-01-01

375

Use of Soil Moisture Probes to Estimate Ground Water Recharge At an Oil Spill Site  

NASA Astrophysics Data System (ADS)

Soil moisture data collected using an automated data logging system were used to estimate ground water recharge at a crude oil spill research site near Bemidji, Minnesota. Three different soil moisture probes were tested in the laboratory as well as the field conditions of limited power supply and extreme weather typical of northern Minnesota: a self-contained reflectometer probe, and two time domain reflectometry (TDR) probes, 30 and 50 cm long. Recharge was estimated using an unsaturated zone water balance method. Recharge estimates for 1999 using the laboratory calibrations were 13 to 30 percent greater than estimates based on the factory calibrations. Recharge indicated by the self-contained probes was 170 percent to 210 percent greater than the estimates for the TDR probes regardless of calibration method. Results indicate that the anomalously large recharge estimates for the self-contained probes are not the result of inaccurate measurements of volumetric moisture content, but result from the presence of crude oil, or borehole leakage. Of the probes tested, the 50 cm long TDR probe yielded recharge estimates that compared most favorably to estimates based on a method utilizing water table fluctuations. Recharge rates for this probe represented 24 to 27 percent of 1999 precipitation. Recharge based on the 30 cm long horizontal TDR probes was 29 to 37 percent of 1999 precipitation. By comparison, recharge based on the water table fluctuation method represented about 29 percent of precipitation.

Delin, Geoffrey N.; Herkelrath, William N.

2005-12-01

376

Estimated ground-water recharge from streamflow in Fortymile Wash near Yucca Mountain, Nevada  

SciTech Connect

The two purposes of this report are to qualitatively document ground-water recharge from stream-flow in Fortymile Wash during the period 1969--95 from previously unpublished ground-water levels in boreholes in Fortymile Canyon during 1982--91 and 1995, and to quantitatively estimate the long-term ground-water recharge rate from streamflow in Fortymile Wash for four reaches of Fortymile Wash (Fortymile Canyon, upper Jackass Flats, lower Jackass Flats, and Amargosa Desert). The long-term groundwater recharge rate was estimated from estimates of the volume of water available for infiltration, the volume of infiltration losses from streamflow, the ground-water recharge volume from infiltration losses, and an analysis of the different periods of data availability. The volume of water available for infiltration and ground-water recharge in the four reaches was estimated from known streamflow in ephemeral Fortymile Wash, which was measured at several gaging station locations. The volume of infiltration losses from streamflow for the four reaches was estimated from a streamflow volume loss factor applied to the estimated streamflows. the ground-water recharge volume was estimated from a linear relation between infiltration loss volume and ground-water recharge volume for each of the four reaches. Ground-water recharge rates were estimated for three different periods of data availability (1969--95, 1983--95, and 1992--95) and a long-term ground-water recharge rate estimated for each of the four reaches.

Savard, C.S.

1998-10-01

377

Representative recharge rates in a complex unsaturated hydrogeology  

SciTech Connect

This study summarizes analyses used for the determination of representative recharge rates in a semi-arid terrain of complex topography for the purpose of modeling the performance assessment of a mesa top disposal facility. Four recharge rates are identified based on different terrains. The terrain is first broadly grouped into canyon bottoms and mesa tops, with each covering about half the topography. The canyon bottoms are considered wet or dry depending on the local infiltration conditions and the influence of mans` activities. The mesa tops are separated into locations which are undisturbed and disturbed by laboratory operations. Disturbed locations at the disposal facility include the disposal pits utilized for shallow land burial of low-level radioactive waste, covering approximately half the mesa top area. Several sources of data and analyses have been synthesized to estimate the resulting recharge rates. Data and analyses include: (1) detailed surface water balance calculations with site-specific parameter values as input; (2) chloride ion profiles and analysis of implied flux at several borehole locations; (3) analyses of liquid and vapor phase vertical flux from moisture profiles with stratigraphic unit averaged unsaturated hydrologic properties; (4) comparison of moisture content field data with values implied from Darcy flux calculations for assumed unit gradient conditions and for stratigraphic unit averaged unsaturated hydrologic properties; (5) liquid flux calculated under self-consistent gradients from field observed moisture profiles and analytic determinations of in-situ moisture potential and conductivity at limited locations; (6) distributions in near surface soil moisture contents expressed as an equivalent vertical flux under unit gradient assumptions; and (7) limited comparisons to tracers available from past disposal operations.

Vold, E.; Newman, B.; Birdsell, K. [and others

1997-02-01

378

Artificial recharge through a thick, heterogeneous unsaturated zone  

USGS Publications Warehouse

Thick, heterogeneous unsaturated zones away from large streams in desert areas have not previously been considered suitable for artificial recharge from ponds. To test the potential for recharge in these settings, 1.3 ?? 10 6 m3 of water was infiltrated through a 0.36-ha pond along Oro Grande Wash near Victorville, California, between October 2002 and January 2006. The pond overlies a regional pumping depression 117 m below land surface and is located where thickness and permeability of unsaturated deposits allowed infiltration and saturated alluvial deposits were sufficiently permeable to allow recovery of water. Because large changes in water levels caused by nearby pumping would obscure arrival of water at the water table, downward movement of water was measured using sensors in the unsaturated zone. The downward rate of water movement was initially as high as 6 m/d and decreased with depth to 0.07 m/d; the initial time to reach the water table was 3 years. After the unsaturated zone was wetted, water reached the water table in 1 year. Soluble salts and nitrate moved readily with the infiltrated water, whereas arsenic and chromium were less mobile. Numerical simulations done using the computer program TOUGH2 duplicated the downward rate of water movement, accumulation of water on perched zones, and its arrival at the water table. Assuming 10 ?? 10 6 m3 of recharge annually for 20 years, a regional ground water flow model predicted water level rises of 30 m beneath the ponds, and rises exceeding 3 m in most wells serving the nearby urban area.

Izbicki, J.A.; Flint, A.L.; Stamos, C.L.

2008-01-01

379

Rechargeable battery which combats shape change of the zinc anode  

NASA Technical Reports Server (NTRS)

A rechargeable cell or battery is provided in which shape change of the zinc anode is combatted by profiling the ionic conductivity of the paths between the electrodes. The ion flow is greatest at the edges of the electrodes and least at the centers, thereby reducing migration of the zinc ions from edges to the center of the anode. A number of embodiments are disclosed in which the strength and/or amount of electrolyte, and/or the number and/or size of the paths provided by the separator between the electrodes, are varied to provide the desired ionic conductivity profile.

Cohn, E. M. (inventor)

1976-01-01

380

High pressure water electrolysis for space station EMU recharge  

NASA Technical Reports Server (NTRS)

A high pressure oxygen recharge system (HPORS), is being developed for application on board the Space Station. This electrolytic system can provide oxygen at up to 6000 psia without a mechanical compressor. The Hamilton standard HPORS based on a solid polymer electrolyte system is an extension of the much larger and succesful 3000 psia system of the U.S. Navy. Cell modules have been successfully tested under conditions beyond which spacecraft may encounter during launch. The control system with double redundancy and mechanical backups for all electronically controlled components is designed to ensure a safe shutdown.

Lance, Nick; Puskar, Michael; Moulthrop, Lawrence; Zagaja, John

1988-01-01

381

Downstream of downtown: urban wastewater as groundwater recharge  

NASA Astrophysics Data System (ADS)

Wastewater infiltration is often a major component of overall recharge to aquifers around urban areas, especially in more arid climates. Despite this, such recharge still represents only an incidental (or even accidental) byproduct of various current practices of sewage effluent handling and wastewater reuse. This topic is reviewed through reference to certain areas of detailed field research, with pragmatic approaches being identified to reduce the groundwater pollution hazard of these practices whilst attempting to retain their groundwater resource benefit. Since urban sewage effluent is probably the only `natural resource' whose global availability is steadily increasing, the socioeconomic importance of this topic for rapidly developing urban centres in the more arid parts of Asia, Africa, Latin America and the Middle East will be apparent. L'infiltration des eaux usées est souvent la composante essentielle de toute la recharge des aquifères des zones urbaines, particulièrement sous les climats les plus arides. Malgré cela, une telle recharge ne constitue encore qu'un sous-produit incident, ou même accidentel, de pratiques courantes variées du traitement de rejets d'égouts et de réutilisation d'eaux usées. Ce sujet est passé en revue en se référant à certaines régions étudiées en détail, par des approches pragmatiques reconnues pour permettre de réduire les risques de pollution des nappes dues à ces pratiques tout en permettant d'en tirer profit pour leur ressource en eau souterraine. Puisque les effluents d'égouts urbains sont probablement la seule « ressource naturelle » dont la disponibilité globale va croissant constamment, l'importance socio-économique de ce sujet est évidente pour les centres urbains à développement rapide de l'Asie, de l'Afrique, de l'Amérique latine et du Moyen-Orient. La infiltración de aguas residuales es a menudo un componente principal de la recarga total en acuíferos ubicados en torno a zonas urbanas, especialmente en los climas más áridos. A pesar de ello, dicho componente todavía es una consecuencia secundaria (o incluso accidental) de diversas prácticas asociadas con la manipulación de las aguas residuales y con la reutilitzación de aguas depuradas. Este tema se revisa mediante referencias a ciertas áreas en las que existen investigación detallada de campo, identificando enfoques pragmáticos con el fin de reducir el riesgo de contaminación de las aguas subterráneas por tales prácticas, a la vez tratando de conservar los beneficios para los recursos del acuífero. Dado que los efluentes de aguas residuales urbanas son probablemente la única `fuente natural' cuya disponibilidad global se halla en del aumento, la importancia socioeconómica de este tema será evidente para los centros urbanos de rápido desarrollo en Asia, Latinoamérica y Oriente Medio.

Foster, S. S. D.; Chilton, P. J.

382

RISING beamline (BL28XU) for rechargeable battery analysis  

PubMed Central

The newly installed BL28XU beamline at SPring-8 is dedicated to in situ structural and electronic analysis of rechargeable batteries. It supports the time range (1?ms to 100?s) and spatial range (1?µm to 1?mm) needed for battery analysis. Electrochemical apparatus for battery charging and discharging are available in experimental hutches and in a preparation room. Battery analysis can be carried out efficiently and effectively using X-ray diffraction, X-ray absorption fine-structure analysis and hard X-ray photoelectron spectroscopy. Here, the design and performance of the beamline are described, and preliminary results are presented. PMID:24365948

Tanida, H.; Fukuda, K.; Murayama, H.; Orikasa, Y.; Arai, H.; Uchimoto, Y.; Matsubara, E.; Uruga, T.; Takeshita, K.; Takahashi, S.; Sano, M.; Aoyagi, H.; Watanabe, A.; Nariyama, N.; Ohashi, H.; Yumoto, H.; Koyama, T.; Senba, Y.; Takeuchi, T.; Furukawa, Y.; Ohata, T.; Matsushita, T.; Ishizawa, Y.; Kudo, T.; Kimura, H.; Yamazaki, H.; Tanaka, T.; Bizen, T.; Seike, T.; Goto, S.; Ohno, H.; Takata, M.; Kitamura, H.; Ishikawa, T.; Ohta, T.; Ogumi, Z.

2014-01-01

383

Rechargeable thin film battery and method for making the same  

DOEpatents

A rechargeable, stackable, thin film, solid-state lithium electrochemical cell, thin film lithium battery and method for making the same is disclosed. The cell and battery provide for a variety configurations, voltage and current capacities. An innovative low temperature ion beam assisted deposition method for fabricating thin film, solid-state anodes, cathodes and electrolytes is disclosed wherein a source of energetic ions and evaporants combine to form thin film cell components having preferred crystallinity, structure and orientation. The disclosed batteries are particularly useful as power sources for portable electronic devices and electric vehicle applications where high energy density, high reversible charge capacity, high discharge current and long battery lifetimes are required.

Goldner, Ronald B.; Liu, Te-Yang; Goldner, Mark A.; Gerouki, Alexandra; Haas, Terry E.

2006-01-03

384

A 65 Ah rechargeable lithium molybdenum disulfide battery  

NASA Technical Reports Server (NTRS)

A rechargeable lithium molybdenum disulfide battery which has a number of superior performance characteristics which includes a high energy density, a high power density, and a long charge retention time was developed. The first cell sizes developed included a C size cell and an AA size cell. Over the last two years, a project to demonstrate the feasibility of the scale up to this technology to a BC size cell with 65 Ah capacity was undertaken. The objective was to develop, build, and test a .6 kWh storage battery consisting of 6 BC cells in series.

Brandt, K.

1986-01-01

385

Using Tracer Tests to Estimate Vertical Recharge and Evaluate Influencing Factors for Irrigated Agricultural Systems  

NASA Astrophysics Data System (ADS)

Accurate estimation of vertical groundwater recharge is critical for (semi) arid regions, especially in places such as the North China Plain where vertical recharge comprises the largest portion of recharge. Tracer tests were used to estimate vertical recharge beneath agricultural systems irrigated by groundwater, and to help delineate factors that influence recharge. Bromide solution was applied to trace infiltration in the vadose zone beneath irrigated agricultural fields (rotated winter wheat and summer maize, orchards, and cotton) and non-irrigated woodlands at both piedmont plain (Shijiazhaung) and alluvial and lacustrine plains (Hengshui) in the North China Plain. The tracer tests lasted for more than two years, and were conducted at a total of 37 sites. Tracer solution was injected into the subsurface at a depth of 1.2 m before the rainy season. Soil samples were then collected periodically to observe bromide transport and estimate recharge rates at the point-scale. For these experiments, the only irrigation the fields received was that applied by the landowners. In addition to these tests, a controlled irrigation experiment was conducted at a single wheat and maize site. The results showed that recharge rates were lower for the alluvial and lacustrine plains sites, which comprise finer-textured soils than those present in the piedmont plain. Specifically, the recharge rate ranged between 56-466 mm/a beneath wheat-maize, 110-564 mm/a beneath orchard, and 0-21 mm/a beneath woodlands with an average recharge coefficient of 0.17 for the piedmont plain sites, while the recharge rate ranged between 26-165 mm/a beneath wheat-maize, 6-40 mm/a beneath orchard, 87-319 mm/a beneath cotton, and 0-32 mm/a beneath woodlands with an average recharge coefficient of 0.10 for the alluvial and lacustrine plain sites. Irrigation provided the primary contribution to recharge, with precipitation providing a minor contribution. The results of both the uncontrolled and controlled irrigation experiments showed that recharge increased as irrigation quantity increased. Overall, recharge was lower for the fields with the rotation cultivation of winter wheat and summer maize compared to the aged apple orchard. In general, the irrigation quantity applied was larger than the requirement of the crops. Thus, managing the irrigation regime to insure that irrigation matches crop requirements would be helpful to better preserve groundwater resources and prevent water-table decline. The recharge rates obtained in this study will be used as input in a mathematical modeling effort designed to simulate the regional groundwater system in the North China Plain.

Lin, D.; Jin, M.; Brusseau, M.; Ma, B.; Liu, Y.

2013-12-01

386

Predicting Groundwater Recharge for the Okanagan Basin: A Little HELP From the Locals  

NASA Astrophysics Data System (ADS)

Estimates of groundwater recharge are an essential component in flow models; however, recharge is highly uncertain and difficult to quantify for dry regions. Since flow models are often used in water management planning, acquiring spatially variable recharge estimates at a comparable scale can be challenging. Regional scale recharge estimates must reflect trends of local scale processes to be effective in planning. This study examined how results from a regional recharge model compared to recharge estimated in separate, local scale models from opposing ends of the Okanagan basin, in British Columbia, Canada. At nearly 8000~km2, the north-south trending basin has a climatic gradient with a warmer, wetter climate in the north and hotter, drier conditions in the south. The region has become a popular area for tourism, residence, and agriculture, particularly orchards and vineyards. With surface water sources close to fully allocated, the region is turning to groundwater as a means to support increasing socioeconomic growth. Basin wide (regional) recharge estimates in the valley bottom are a critical step in managing groundwater resources. Regional estimates of recharge were determined with the Hydrologic Evaluation of Landfill Performance (HELP) code by establishing common areas of soil texture, water table depth and three other hydrologic parameters. Results from the regional scale were compared with two independently derived, local scale estimates of groundwater recharge. For the south Okanagan, regional estimates were compared with results from a high-resolution integrated HELP and MODFLOW analysis; and in the north Okanagan, regional estimates were compared to results from a study utilizing the Richards equation based MIKE-SHE code. Comparison with these two models, calculated in areas at each end of the climatic gradient, provide confidence in developing a map of regional groundwater recharge. Preliminary results illustrate the applicability of HELP for predicting basin-wide recharge for areas with shallow slope (limited runoff), accurate depth to water table (from a water well database), and detailed descriptions of vadose zone lithology.

Liggett, J. E.; Toews, M. W.; Smerdon, B. D.; Allen, D. M.

2007-12-01

387

Numerical assessment of ASR recharge using small-diameter wells and surface basins  

NASA Astrophysics Data System (ADS)

Aquifer storage and recovery (ASR) methods are increasingly used to overcome the temporal imbalance between water demand and availability. Common ASR recharge methods utilize large-diameter injection wells or surface infiltration basins and trenches, and can be costly to implement. A new low-cost ASR recharge method is currently being developed. This approach is based on recharge via gravity in small-diameter wells installed with direct-push (DP) technology. Numerical modeling is used here to assess the potential of this new approach under conditions commonly faced in field settings. The primary objective is to investigate if a battery of small-diameter DP wells can serve as a viable alternative to a surface basin under typical field conditions, while the secondary objective is to assess which subsurface parameters have the greatest control on DP well performance. Simulation results indicate that gravity recharge via small-diameter wells appears to have a distinct advantage over recharge via surface infiltration basins. For example, two 0.05-m shallow vadose-zone wells with 9-m screens can recharge water at a greater rate than a 60 m2 basin. Also, results reveal that, contrary to an infiltration basin, the recharge rate in a DP well has a much stronger dependence on the horizontal component of hydraulic conductivity than on the vertical component. Moreover, near-surface layers of low hydraulic conductivity, which can significantly reduce the recharge capacity of a surface basin, have a relatively small impact on the recharge capacity of a well as long as a significant portion of the well screen is installed below those layers. Given that installation and operation costs can be low in comparison to common ASR recharge methods, this new approach appears to have great potential for recharging good quality water in shallow unconsolidated aquifers. A field investigation has recently been initiated to follow up the findings of this simulation assessment.

Händel, Falk; Liu, Gaisheng; Dietrich, Peter; Liedl, Rudolf; Butler, James J.

2014-09-01

388

Ground truthing groundwater-recharge estimates derived from remotely sensed evapotranspiration: a case in South Australia  

NASA Astrophysics Data System (ADS)

Using a water balance to estimate groundwater recharge through the use of remotely sensed evapotranspiration offers a spatial and temporal density of data that other techniques cannot match. However, the estimates are uncertain and therefore ground truthing of the recharge estimates is necessary. This study, conducted in the south-east of South Australia, demonstrated that the raw water-balance estimates of recharge had a negative bias of 45 mm/yr when compared to 190 recharge estimates using the water-table fluctuation method over a 10-year period (2001-2010). As this bias was not related to the magnitude of the recharge estimated using the water-table fluctuation method, a simple offset was used to bias-correct the water-balance recharge estimates. The bias-corrected recharge estimates had a mean residual that was not significantly different from an independent set of 99 historical recharge estimates but did have a large mean absolute residual indicating a lack of precision. The value in this technique is the density of the data (250-m grid over 29,000 km2). The relationship between the water-table depth and net recharge under different vegetation types was investigated. Under pastures, there was no relationship with water-table depth, as the shallow roots do not intercept groundwater. However, under plantation forestry, there was a relationship between net recharge and water-table depth. Net recharge under plantation forestry growing on sandy soils was independent of the water table at around 6 m depth but, under heavier textured soils, the trees were using groundwater from depths of more than 20 m.

Crosbie, Russell S.; Davies, Phil; Harrington, Nikki; Lamontagne, Sebastien

2015-03-01

389

Using 14C and 3H to understand groundwater flow and recharge in an aquifer window  

NASA Astrophysics Data System (ADS)

Knowledge of groundwater residence times and recharge locations are vital to the sustainable management of groundwater resources. Here we investigate groundwater residence times and patterns of recharge in the Gellibrand Valley, southeast Australia, where outcropping aquifer sediments of the Eastern View Formation form an "aquifer window" that may receive diffuse recharge and recharge from the Gellibrand River. To determine recharge patterns and groundwater flowpaths, environmental isotopes (3H, 14C, ?13C, ?18O, ?2H) are used in conjunction with groundwater geochemistry and continuous monitoring of groundwater elevation and electrical conductivity. Despite the water table fluctuating by 0.9-3.7 m annually producing estimated recharge rates of 90 and 372 mm yr-1, residence times of shallow (11-29 m) groundwater determined by 14C ages are between 100 and 10 000 years. 3H activities are negligible in most of the groundwater and groundwater electrical conductivity in individual areas remains constant over the period of study. Although diffuse local recharge is evident, the depth to which it penetrates is limited to the upper 10 m of the aquifer. Rather, groundwater in the Gellibrand Valley predominantly originates from the regional recharge zone, the Barongarook High, and acts as a regional discharge zone where upward head gradients are maintained annually, limiting local recharge. Additionally, the Gellibrand River does not recharge the surrounding groundwater and has limited bank storage. 14C ages and Cl concentrations are well correlated and Cl concentrations may be used to provide a first-order estimate of groundwater residence times. Progressively lower chloride concentrations from 10 000 years BP to the present day are interpreted to indicate an increase in recharge rates on the Barongarook High.

Atkinson, A. P.; Cartwright, I.; Gilfedder, B. S.; Cendón, D. I.; Unland, N. P.; Hofmann, H.

2014-06-01

390

Using 14C and 3H to understand groundwater flow and recharge in an aquifer window  

NASA Astrophysics Data System (ADS)

Knowledge of groundwater residence times and recharge locations is vital to the sustainable management of groundwater resources. Here we investigate groundwater residence times and patterns of recharge in the Gellibrand Valley, southeast Australia, where outcropping aquifer sediments of the Eastern View Formation form an "aquifer window" that may receive diffuse recharge from rainfall and recharge from the Gellibrand River. To determine recharge patterns and groundwater flow paths, environmental isotopes (3H, 14C, ?13C, ?18O, ?2H) are used in conjunction with groundwater geochemistry and continuous monitoring of groundwater elevation and electrical conductivity. The water table fluctuates by 0.9 to 3.7 m annually, implying recharge rates of 90 and 372 mm yr-1. However, residence times of shallow (11 to 29 m) groundwater determined by 14C are between 100 and 10 000 years, 3H activities are negligible in most of the groundwater, and groundwater electrical conductivity remains constant over the period of study. Deeper groundwater with older 14C ages has lower ?18O values than younger, shallower groundwater, which is consistent with it being derived from greater altitudes. The combined geochemistry data indicate that local recharge from precipitation within the valley occurs through the aquifer window, however much of the groundwater in the Gellibrand Valley predominantly originates from the regional recharge zone, the Barongarook High. The Gellibrand Valley is a regional discharge zone with upward head gradients that limits local recharge to the upper 10 m of the aquifer. Additionally, the groundwater head gradients adjacent to the Gellibrand River are generally upwards, implying that it does not recharge the surrounding groundwater and has limited bank storage. 14C ages and Cl concentrations are well correlated and Cl concentrations may be used to provide a first-order estimate of groundwater residence times. Progressively lower chloride concentrations from 10 000 years BP to the present day are interpreted to indicate an increase in recharge rates on the Barongarook High.

Atkinson, A. P.; Cartwright, I.; Gilfedder, B. S.; Cendón, D. I.; Unland, N. P.; Hofmann, H.

2014-12-01

391

Reconnaissance Estimates of Recharge Based on an Elevation-dependent Chloride Mass-balance Approach  

SciTech Connect

Significant uncertainty is associated with efforts to quantity recharge in arid regions such as southern Nevada. However, accurate estimates of groundwater recharge are necessary to understanding the long-term sustainability of groundwater resources and predictions of groundwater flow rates and directions. Currently, the most widely accepted method for estimating recharge in southern Nevada is the Maxey and Eakin method. This method has been applied to most basins within Nevada and has been independently verified as a reconnaissance-level estimate of recharge through several studies. Recharge estimates derived from the Maxey and Eakin and other recharge methodologies ultimately based upon measures or estimates of groundwater discharge (outflow methods) should be augmented by a tracer-based aquifer-response method. The objective of this study was to improve an existing aquifer-response method that was based on the chloride mass-balance approach. Improvements were designed to incorporate spatial variability within recharge areas (rather than recharge as a lumped parameter), develop a more defendable lower limit of recharge, and differentiate local recharge from recharge emanating as interbasin flux. Seventeen springs, located in the Sheep Range, Spring Mountains, and on the Nevada Test Site were sampled during the course of this study and their discharge was measured. The chloride and bromide concentrations of the springs were determined. Discharge and chloride concentrations from these springs were compared to estimates provided by previously published reports. A literature search yielded previously published estimates of chloride flux to the land surface. {sup 36}Cl/Cl ratios and discharge rates of the three largest springs in the Amargosa Springs discharge area were compiled from various sources. This information was utilized to determine an effective chloride concentration for recharging precipitation and its associated uncertainty via Monte Carlo simulations. Previously developed isohyetal maps were utilized to determine the mean and standard deviation of precipitation within the area. A digital elevation model was obtained to provide elevation information. A geologic model was obtained to provide the spatial distribution of alluvial formations. Both were used to define the lower limit of recharge. In addition, 40 boreholes located in alluvial sediments were drilled and sampled in an attempt to support the argument that the areal distribution of alluvial sediments can be used to define a zone of negligible recharge. The data were compiled in a geographic information system and used in a Monte Carlo analysis to determine recharge occurring within the study area. Results of the analysis yielded estimates of the mean and standard deviation of recharge occurring within the study area (28.168 x 10{sup 6} m{sup 3} yr{sup -1} and 7.008 x 10{sup 6} m{sup 3} yr{sup -1}, and 26.838 x 10{sup 6} m{sup 3} yr{sup -1} and 6.928 x 10{sup 6} m{sup 3} yr{sup -1}) for two sets of simulations using alternate definitions of the lower limit of recharge. A sensitivity analysis determined the recharge estimates were most sensitive to uncertainty associated with the chloride concentration of the spring discharge. The second most sensitive parameter was the uncertainty associated with the mean precipitation within the recharge areas. Comparison of the analysis to previously published estimates of recharge revealed mixed results with the recharge estimates derived during the course of this project generally greater relative to previously published estimates.

Charles E. Russell; Tim Minor

2002-08-31

392

Tunable Aqueous Virtual Micropore  

PubMed Central

A charged micro-particle can be trapped in an aqueous environment by forming a narrow virtual pore – a cylindrical space region in which the particle motion in the radial direction is limited by forces emerging from dynamical interactions of the particle charge and dipole moment with external radio-frequency quadrupole electric field. If the particle satisfies the trap stability criteria its mean motion is reduced exponentially with time due to the viscosity of the aqueous environment. Thereafter the long-time motion of particle is subject only to random, Brownian fluctuations, whose magnitude, influenced by the electrophoretic and dielectrophoretic effects and added to the particle size, determines the radius of the virtual pore, which we demonstrate by comparison of computer simulations and experiment. The measured size of the virtual nanopore could be utilized to estimate the charge of a trapped micro-object. PMID:22271580

Park, Jae Hyun; Guan, Weihua; Reed, Mark A.; Krsti?, Predrag S.

2012-01-01

393

Lithium ion aqueous cells  

NASA Astrophysics Data System (ADS)

Lithium ion aqueous cells were investigated using lithium intercalating compounds as anodes and cathodes. The aqueous electrolyte consisted of 4 to 5 molar solutions of either lithium perchlorate or lithium nitrate which contained lithium hydroxide in millimolar amounts to make the solutions slightly basic with a pH of about 8.5. Several electrode combinations were evaluated using lithium intercalating compounds such as lithium cobalt oxide and lithium manganese oxide as cathodes and lithium vanadium oxide, lithium manganese oxide, titanium disulfide, and molybdenum dioxide as the anodes. The cell employing manganese oxide as both the anode and cathode exhibited good charge-discharge characteristics with an open circuit potential of about one volt.

Plichta, Edward J.; Behl, Wishvender K.

1995-02-01

394

Mars aqueous chemistry experiment  

NASA Technical Reports Server (NTRS)

The Mars Aqueous Chemistry Experiment (MACE) is designed to conduct a variety of measurements on regolith samples, encompassing mineral phase analyses, chemical interactions with H2O, and physical properties determinations. From these data, much can be learned or inferred regarding the past weathering environment, the contemporaneous soil micro-environments, and the general chemical and physical state of the Martian regolith. By analyzing both soil and duricrust samples, the nature of the latter may become more apparent. Sites may be characterized for comparative purposes and criteria could be set for selection of high priority materials on future sample return missions. Progress for the first year MACE PIDDP is reported in two major areas of effort: (1) fluids handling concepts, definition, and breadboard fabrication and (2) aqueous chemistry ion sensing technology and test facility integration. A fluids handling breadboard was designed, fabricated, and tested at Mars ambient pressure. The breadboard allows fluid manipulation scenarios to be tested under the reduced pressure conditions expected in the Martian atmosphere in order to validate valve operations, orchestrate analysis sequences, investigate sealing integrity, and to demonstrate efficacy of the fluid handling concept. Additional fluid manipulation concepts have also been developed based on updated MESUR spacecraft definition. The Mars Aqueous Chemistry Experiment Ion Selective Electrode (ISE) facility was designed as a test bed to develop a multifunction interface for measurements of chemical ion concentrations in aqueous solution. The interface allows acquisition of real time data concerning the kinetics and heats of salt dissolution, and transient response to calibration and solubility events. An array of ion selective electrodes has been interfaced and preliminary calibration studies performed.

Clark, Benton C.; Mason, Larry W.

1993-01-01

395

Continuous aqueous tritium monitor  

DOEpatents

An apparatus for a selective on-line determination of aqueous tritium concentration is disclosed. A moist air stream of the liquid solution being analyzed is passed through a permeation dryer where the tritium and moisture are selectively removed to a purge air stream. The purge air stream is then analyzed for tritium concentration, humidity, and temperature, which allows computation of liquid tritium concentration. 2 figs.

McManus, G.J.; Weesner, F.J.

1987-10-19

396

Feasibility of groundwater recharge dam projects in arid environments  

NASA Astrophysics Data System (ADS)

A new method for determining feasibility and prioritizing investments for agricultural and domestic recharge dams in arid regions is developed and presented. The method is based on identifying the factors affecting the decision making process and evaluating these factors, followed by determining the indices in a GIS-aided environment. Evaluated parameters include results from field surveys and site visits, land cover and soils data, precipitation data, runoff data and modeling, number of beneficiaries, domestic irrigation demand, reservoir objectives, demography, reservoirs yield and reliability, dam structures, construction costs, and operation and maintenance costs. Results of a case study on more than eighty proposed dams indicate that assessment of reliability, annualized cost/demand satisfied and yield is crucial prior to investment decision making in arid areas. Irrigation demand is the major influencing parameter on yield and reliability of recharge dams, even when only 3 months of the demand were included. Reliability of the proposed reservoirs as related to their standardized size and net inflow was found to increase with increasing yield. High priority dams were less than 4% of the total, and less priority dams amounted to 23%, with the remaining found to be not feasible. The results of this methodology and its application has proved effective in guiding stakeholders for defining most favorable sites for preliminary and detailed design studies and commissioning.

Jaafar, H. H.

2014-05-01

397

Natural water purification and water management by artificial groundwater recharge  

PubMed Central

Worldwide, several regions suffer from water scarcity and contamination. The infiltration and subsurface storage of rain and river water can reduce water stress. Artificial groundwater recharge, possibly combined with bank filtration, plant purification and/or the use of subsurface dams and artificial aquifers, is especially advantageous in areas where layers of gravel and sand exist below the earth’s surface. Artificial infiltration of surface water into the uppermost aquifer has qualitative and quantitative advantages. The contamination of infiltrated river water will be reduced by natural attenuation. Clay minerals, iron hydroxide and humic matter as well as microorganisms located in the subsurface have high decontamination capacities. By this, a final water treatment, if necessary, becomes much easier and cheaper. The quantitative effect concerns the seasonally changing river discharge that influences the possibility of water extraction for drinking water purposes. Such changes can be equalised by seasonally adapted infiltration/extraction of water in/out of the aquifer according to the river discharge and the water need. This method enables a continuous water supply over the whole year. Generally, artificially recharged groundwater is better protected against pollution than surface water, and the delimitation of water protection zones makes it even more save. PMID:18357624

Balke, Klaus-Dieter; Zhu, Yan

2008-01-01

398

Natural water purification and water management by artificial groundwater recharge.  

PubMed

Worldwide, several regions suffer from water scarcity and contamination. The infiltration and subsurface storage of rain and river water can reduce water stress. Artificial groundwater recharge, possibly combined with bank filtration, plant purification and/or the use of subsurface dams and artificial aquifers, is especially advantageous in areas where layers of gravel and sand exist below the earth's surface. Artificial infiltration of surface water into the uppermost aquifer has qualitative and quantitative advantages. The contamination of infiltrated river water will be reduced by natural attenuation. Clay minerals, iron hydroxide and humic matter as well as microorganisms located in the subsurface have high decontamination capacities. By this, a final water treatment, if necessary, becomes much easier and cheaper. The quantitative effect concerns the seasonally changing river discharge that influences the possibility of water extraction for drinking water purposes. Such changes can be equalised by seasonally adapted infiltration/extraction of water in/out of the aquifer according to the river discharge and the water need. This method enables a continuous water supply over the whole year. Generally, artificially recharged groundwater is better protected against pollution than surface water, and the delimitation of water protection zones makes it even more save. PMID:18357624

Balke, Klaus-Dieter; Zhu, Yan

2008-03-01

399

Rechargeable Li/Li(1+x)V308 cells  

NASA Astrophysics Data System (ADS)

Murphy et al. (1981) and Abraham et al. (1981) have investigated the possibility of a use of transition metal oxides as substitutes of TiS2 in cathodes for rechargeable Li cells, giving particular attention to the V compounds of formula V6O(13+y) with y less than 0.2. The considered materials have greater energy densities than TiS2. However, an important drawback is reported for both V6O13.16 (nonstoichiometric). At 1.6 V a reduction process occurs which inhibits further rechargeability. This phenomenon is probably related to irreversible structure reorganizations connected with the high Li(+) content. In connection with the present investigation, it has been attempted to overcome the considered drawback by using a material, which while retaining the basic electrochemical features of V6O(13+y), would be able to undergo overdischarges without strucural damage. The use of Li(1+x)V308 has been investigated in this connection.

Panero, S.; Pasquali, M.; Pistoia, G.

1983-05-01

400

The Guarani Aquifer System: estimation of recharge along the Uruguay-Brazil border  

NASA Astrophysics Data System (ADS)

The cities of Rivera and Santana do Livramento are located on the outcropping area of the sandstone Guarani Aquifer on the Brazil-Uruguay border, where the aquifer is being increasingly exploited. Therefore, recharge estimates are needed to address sustainability. First, a conceptual model of the area was developed. A multilayer, heterogeneous and anisotropic groundwater-flow model was built to validate the conceptual model and to estimate recharge. A field campaign was conducted to collect water samples and monitor water levels used for model calibration. Field data revealed that there exists vertical gradients between confining basalts and underlying sandstones, suggesting basalts could indirectly recharge sandstone in fractured areas. Simulated downward flow between them was a small amount within the global water budget. Calibrated recharge rates over basalts and over outcropping sandstones were 1.3 and 8.1% of mean annual precipitation, respectively. A big portion of sandstone recharge would be drained by streams. The application of a water balance yielded a recharge of 8.5% of average annual precipitation. The numerical model and the water balance yielded similar recharge values consistent with determinations from previous authors in the area and other regions of the aquifer, providing an upper bound for recharge in this transboundary aquifer.

Gómez, Andrea A.; Rodríguez, Leticia B.; Vives, Luis S.

2010-11-01

401

Estimation of groundwater recharge to chalk and sandstone aquifers using simple soil models  

Microsoft Academic Search

On the assumption that the water draining below the root zone is potentially available for groundwater recharge, two current UK methods for estimating annual groundwater recharge have been compared with a new soil model using data from four sites under permanent grass in the UK: two sites representative of the Chalk aquifer at Bridgest Farm (Hampshire) and Fleam Dyke (Cambridgeshire),

R. Ragab; J. Finch; R. Harding

1997-01-01

402

Influence of model conceptualisation on one-dimensional recharge quantification: Uley South, South Australia  

NASA Astrophysics Data System (ADS)

Model conceptualisation is a key source of uncertainty in one-dimensional recharge modelling. The effects of different conceptualisations on transient recharge predictions for the semi-arid Uley South Basin, South Australia, were investigated. One-dimensional unsaturated zone modelling was used to quantify the effect of variations of (1) lithological complexity of the unsaturated zone, and (2) representation of preferential flow pathways. The simulations considered ranges of water-table depths, vegetation characteristics, and top soil thicknesses representative for the study area. Complex lithological profiles were more sensitive to the selected vegetation characteristics and water-table depth. Scenarios considering runoff infiltration into, and preferential flow through sinkholes resulted in higher and faster recharge rates. A comparison of modelled and field-based recharge estimates indicated that: (1) the model simulated plausible recharge rates, (2) only the models with preferential flow correctly reproduced the timing of recharge, and (3) preferential flow is probably redistributed in the unsaturated zone rather than passing to the water table directly. Because different but equally plausible conceptual models produce widely varying recharge rates, field-based recharge estimates are essential to constrain the modelling results.

Ordens, Carlos M.; Post, Vincent E. A.; Werner, Adrian D.; Hutson, John L.

2014-06-01

403

Recharge into Southern High Plains aquifer—possible mechanisms, unresolved questions  

NASA Astrophysics Data System (ADS)

The High Plains aquifer in the Southern High Plains (Texas and New Mexico), consisting of Tertiary, Cretaceous, and Triassic formations, has traditionally been considered to be recharged by its uppermost water-bearing unit, the Tertiary Ogallala aquifer. This article provides hydrologic, chemical, and isotopic evidence that in the Southern High Plains: (1) Cretaceous rocks actually contain independent recharge sources; (2) Triassic rocks cannot currently be recharged by the Ogallala aquifer in significant quantities; and (3) in places, both Cretaceous and Triassic aquifers recharge the overlying Ogallala aquifer. On the basis of chemical and isotopic data, playa lakes seem to act as the predominant recharge source of the Ogallala aquifer, suggesting recharge rates greater than 30 mm/yr, as opposed to the much lower rates reported by others. The Cretaceous aquifers are being recharged by cross-formational flow from the Ogallala aquifer but also from overlying Quaternary sands and the underlying Triassic aquifer in eastern New Mexico. Current recharge into the Triassic aquifer may be insignificant.

Nativ, Ronit

1992-01-01

404

EVALUATING UNCERTAINTIES IN GROUND-WATER RECHARGE ESTIMATES THROUGH ADVANCED MONITORING  

Technology Transfer Automated Retrieval System (TEKTRAN)

Risk, as estimated by many multimedia environmental models, is highly sensitive to infiltration and ground-water recharge. This field study used high-frequency monitoring of vadose-zone water content and piezometric levels to build confidence in modeling of infiltration and ground-water recharge. ...

405

Groundwater-recharge estimation in the Ordos Plateau, China: comparison of methods  

NASA Astrophysics Data System (ADS)

Groundwater recharge is a key factor in water-balance studies, especially in (semi-)arid areas. In this study, multiple methods were used to estimate groundwater recharge in the Ordos Plateau (China), including reference to water-table fluctuation, Darcy's law and the water budget. The mean annual recharge rates found were: water-table-fluctuation method (46-109 mm/yr); saturated-zone Darcian method (17-54 mm/yr); and water-budget method (21-109 mm/yr). Generally, groundwater-recharge rates are higher in the eastern part of the plateau where the land surface is covered by permeable sand that is favorable for infiltration. Along with results from previous studies using the empirical method, the chloride-mass-balance method, the unsaturated-zone Darcian method and the hydrograph-separation method, groundwater recharge rates were compared. There is no one method that would consistently produce the largest or smallest estimate of annual recharge for all groundwater systems. The largest recharge estimates were usually determined using the unsaturated-zone Darcian method and the smallest estimates were usually determined using the chloride-mass-balance method. Comparison of multiple methods is found to be valuable for determining the range of plausible recharge rates and for highlighting the uncertainty of the estimates.

Yin, Lihe; Hu, Guangcheng; Huang, Jinting; Wen, Dongguang; Dong, Jiaqiu; Wang, Xiaoyong; Li, Hongbo

2011-12-01

406

Estimate of recharge from radiocarbon dating of groundwater and numerical flow and transport modeling  

E-print Network

Estimate of recharge from radiocarbon dating of groundwater and numerical flow and transport, Pennsylvania Abstract. This paper combines radiocarbon age and hydraulic data to estimate recharge. In this paper, we use 14 C dating of groundwater from the saturated zone and a linked numerical flow

Polly, David

407

A numerical analysis on the applicability of the water level fluctuation method for quantifying groundwater recharge  

Microsoft Academic Search

The water table fluctuation(WTF) method is a conventional method for quantifying groundwater recharge by multiplying the specific yield to the water level rise. Based on the van Genuchten model, an analytical relationship between groundwater recharge and the water level rise is derived. The equation is used to analyze the effects of the depth to water level and the soil properties

M. Koo; D. Lee

2002-01-01

408

A method of estimating spatio-temporally distributed groundwater recharge using integrated surface-subsurface modelling  

Microsoft Academic Search

In general, there have been various methods of estimating groundwater recharge such as baseflow separation approaches, water budget analyses based on lumped conceptual models, and the water table fluctuation method (WTF) by using data from groundwater monitoring wells. However, groundwater recharge rates show spatial-temporal variability due to climatic conditions, land use, and hydrogeological heterogeneity, so these methods have various limitations

Il Moon Chung; Nam Won Kim; Jeongwoo Lee; Marios Sophocleous

2010-01-01

409

Statistical analysis of hydrographs and water-table fluctuation to estimate groundwater recharge  

Microsoft Academic Search

Using water-table monitoring data from the National Groundwater Monitoring Network in Korea, groundwater hydrographs were classified into five typical groups. Then, to estimate groundwater recharge, a modified water-table fluctuation (WTF) method was developed from the relation between the cumulative WTF and corresponding precipitation records. Applying this method to different types of hydrographs, the spatial variability of recharge in river basins

Sang-Ki Moon; Nam C Woo; Kwang S Lee

2004-01-01

410

Groundwater recharge in natural dune systems and agricultural ecosystems in the Thar Desert region, Rajasthan, India  

E-print Network

Groundwater recharge in natural dune systems and agricultural ecosystems in the Thar Desert region be sustainable. Keywords India . Groundwater recharge/water budget . Nutrients . Land use . Sustainability). Groundwater availability problems are likely to be exacerbated in the future by climate change. Average

Scanlon, Bridget R.

411

Climate Change Impact on Groundwater Recharge: A Case Study in Taiwan  

Microsoft Academic Search

Climate change may result in variety of climate and streamflow characteristics. These will further induce influences of groundwater recharge. Therefore, this study assessed the impact of climate change on groundwater recharge through evaluating the change of streamflow under different scenarios. Projection of precipitation or temperature impacted by climate change is of great uncertainty, thus three Global Circulation Models (GCMs), i.e.

K. Ke; C. Tung; C. Tan; P. Yu

2008-01-01

412

USING REMOTE SENSING DATA TO MODEL GROUNDWATER RECHARGE POTENTIAL IN KANYE REGION, BOTSWANA  

Microsoft Academic Search

This study focuses on the groundwater recharge potential in the upper Limpopo catchment starting from Kanye region in South Botswana. Existing high resolution remote sensing data were used to estimate the spatial distribution of potential recharge and discharge of aquifers in this semi-arid region. 29 NOAA AVHRR images available for Southern and Central Botswana between 1996 and 2000 were analyzed

Haijing Wang; Lesego Kgotlhang; Wolfgang Kinzelbach

413

Optimal Operation of Artificial Groundwater Recharge Systems Considering Water Quality Transformations  

Microsoft Academic Search

In water limited areas as water demand increases alternative sustainable water sources must be identified. One supply augmentation practice, that is already being applied in the arid southwest U.S., is artificial groundwater recharge usingwastewater effluent. The objective of a recharge facility is to supplement the available groundwater resources by storing water for the future. The resulting reclaimed water is used

Muzaffar M. Eusuff; Kevin E. Lansey

2004-01-01

414

Data-Conditioned Distributions of Groundwater Recharge Under Climate Change Scenarios  

Microsoft Academic Search

Groundwater recharge is likely to be impacted by climate change, with changes in precipitation amounts altering moisture availability and changes in temperature affecting evaporative demand. This could have major implications for sustainable aquifer pumping rates and contaminant transport into groundwater reservoirs in the future, thus making predictions of recharge under climate change very important. Unfortunately, in dry environments where groundwater

D. McLaughlin; G. C. Ng; D. Entekhabi; B. Scanlon

2008-01-01

415

Groundwater Recharge Modeling in Azraq Basin (Jordan) Considering the Unsaturated Flow Components  

Microsoft Academic Search

Water resources in Azraq basin at the northeastern part of Jordan are at critical juncture, due to the continual and excessive abstraction of groundwater accompanied with small amounts of groundwater recharge by precipitation, and high rates of evaporation losses over the entire basin. Groundwater recharge from precipitation over the basin was estimated using soil water balance. It was found that

M. Al Sharif; T. Al Jazzar

2009-01-01

416

Rapid Recharge to Perched-Intermediate Groundwater Zones, Pajarito Plateau, Los Alamos, New Mexico  

Microsoft Academic Search

The Los Alamos National Laboratory continuously monitors groundwater levels and surface-water discharge at over 150 locations on the Pajarito Plateau. The resulting data sets were analyzed to help identify locations where surface water and shallow alluvial groundwater (generally <30 ft) recharge deeper perched- intermediate groundwater (approximately 200 to 700 ft bgs) zones. Runoff from snowmelt and summer rainstorms recharges the

K. D. Reid; R. J. Koch; D. Katzman; K. H. Birdsell; D. E. Broxton; V. V. Vesselinov

2008-01-01

417

PROSPECTS FOR ENHANCED GROUNDWATER RECHARGE VIA INFILTRATION OF URBAN STORMWATER RUNOFF: A CASE STUDY  

EPA Science Inventory

The rain garden is an urban storm water best management practice that is used to infiltrate runoff close to its source, thereby disconnecting impervious area while providing an avenue for groundwater recharge. Groundwater recharge may provide additional benefits to aquatic ecosys...

418

Estimating recharge through Playa Lakes to the Southern High Plains Aquifer  

Technology Transfer Automated Retrieval System (TEKTRAN)

In the Southern High Plains of Texas, it is accepted that focused recharge to the High Plains Aquifer (locally known as the Ogallala) occurs through over 20,000 playa lakes, which are local depressions that collect storm runoff. The amount and rate of recharge is not precisely known, and the impact ...

419

A ROOT ZONE MODELLING APPROACH TO ESTIMATING GROUNDWATER RECHARGE FROM IRRIGATED AREAS  

Technology Transfer Automated Retrieval System (TEKTRAN)

In irrigated semi-arid and arid regions, accurate knowledge of groundwater recharge is important for the sustainable management of scarce water resources. The Campo de Cartagena area of southeast Spain is a semi-arid region where irrigation return flow accounts for a substantial portion of recharge....

420

Silicon nanowires as a rechargeable template for hydride transfer in redox biocatalysis  

NASA Astrophysics Data System (ADS)

We report a new possible application of hydrogen-terminated silicon nanowires (H-SiNWs) as a rechargeable template for hydride transfer in redox biocatalysis. H-SiNWs transfer hydride efficiently to regenerate NADH by oxidizing Si-Hx bonds. The oxidized H-SiNWs were readily recharged for the continuous regeneration of NADH and enzymatic reactions.

Lee, Hwa Young; Kim, Jae Hong; Son, Eun Jin; Park, Chan Beum

2012-11-01

421

Mode changing stability of wind turbine in an integrated wind turbine and rechargeable battery system  

Microsoft Academic Search

Power generated by wind turbines changes due to variation in wind speed that is independent of the load power. Rechargeable batteries could be used as a reserve power source to alleviate unbalance between the load power and power generated by wind turbines. A supervisory controller is proposed for an integrated wind turbine-battery system (wind turbine electrically connected to a rechargeable

Christine A. Mecklenborg; Dushyant Palejiya; John F. Hall; Dongmei Chen

2011-01-01

422

Ground-water recharge near Santa Fe, north-central New Mexico  

USGS Publications Warehouse

Recharge to the basin-fill aquifer near Santa Fe, New Mexico, was investigated using chloride mass-balance methods. Chloride concentrations in water in the unsaturated zone indicate no recharge in areas where runoff and flooding do not occur. The mass of chloride stored in the upper part of the unsaturated zone in these areas would take about 6,000 to 8,000 years to accumulate, assuming the present (1989) chloride fluxes. Chloride concen- trations in water in the unsaturated zone beneath arroyo channels indicate that recharge does occur in these areas; chloride concentrations in this recharge water at two sites ranged from 40 to 60 milligrams per liter. Estimates of mountain-front recharge using a chloride balance in drainage basins are about 2,320 acre-feet per year in the Santa Fe River drainage, 690 acre-feet per year in the Rio Tesuque drainage, and 830 acre-feet per year in the Anoyo Hondo drainage. Stable isotopes of hydrogen and oxygen indicate that little summer precipitation recharges the ground-water system and that winter precipitation results in most of the recharge water. Most hydrogen and oxygen isotope data for ground water in the area coincide with the local meteoric water line on a graph showing the relation between oxygen and hydrogen in ground water. This indicates that, on the basis of the hydrogen and oxygen isotopic composition of ground water and precipi- tation, evaporation of recharge water or ground water does not occur.

Anderholm, S.K.

1994-01-01

423

Recharge to the interdune lakes and Holocene climatic changes in the Badain Jaran Desert, western China  

Microsoft Academic Search

We present new estimates on evaporation and groundwater recharge in the Badain Jaran Desert, western Inner Mongolia of northwestern China, based on a modified Penman Equation suitable for lakes in China. Geochemical data and water balance calculations suggest that local rainfall makes a significant contribution to groundwater recharge and that past lake-level variations in this desert environment should reflect palaeoclimatic

Xiaoping Yang; Nina Ma; Jufeng Dong; Bingqi Zhu; Bing Xu; Zhibang Ma; Jiaqi Liu

2010-01-01

424

Fullerenes: non-transition metal clusters as rechargeable magnesium battery cathodes.  

PubMed

We discovered that non-transition metal clusters have great potential as rechargeable Mg battery cathodes. Fullerene (C60), one of the prototype materials, was discharged and recharged with a remarkable rate capability. This unique rate performance is attributed to its capability to delocalize electrons on the entire cluster rather than to individual atoms. PMID:25461490

Zhang, Ruigang; Mizuno, Fuminori; Ling, Chen

2015-01-21

425

DISTRIBUTION OF AREAL RECHARGE TO A DISCRETE FRACTURE NETWORK (FRACNET) MODEL USING THE ANALYTIC ELEMENT METHOD  

EPA Science Inventory

Rain water filtering down through the soil will provide recharge of the saturated fractured rock aquifer. he computer model FRACNET has been designed to distribute areal recharge into linear fracture zones in order to complete the regional water balance. n this presentation, a te...

426

Chemical modifications of groundwater contaminated by recharge of treated sewage effluent  

Microsoft Academic Search

Long-term monitoring of the chemical composition of recharge sewage effluent and associated contaminated groundwater from the Dan Region Sewage Reclamation Project shows, after 16 years of recharge operation, the presence of a distinct saline plume (up to 400 mg\\/l Cl), extending 1600 m downgradient in the Coastal Plain aquifer of Israel. The recorded electrolyte composition of groundwater in the vicinity

Avner Vengosh; Rami Keren

1996-01-01

427

Importance of unsaturated zone flow for simulating recharge in a humid climate  

USGS Publications Warehouse

Transient recharge to the water table is often not well understood or quantified. Two approaches for simulating transient recharge in a ground water flow model were investigated using the Trout Lake watershed in north-central Wisconsin: (1) a traditional approach of adding recharge directly to the water table and (2) routing the same volume of water through an unsaturated zone column to the water table. Areas with thin (less than 1 m) unsaturated zones showed little difference in timing of recharge between the two approaches; when water was routed through the unsaturated zone, however, less recharge was delivered to the water table and more discharge occurred to the surface because recharge direction and magnitude changed when the water table rose to the land surface. Areas with a thick (15 to 26 m) unsaturated zone were characterized by multimonth lags between infiltration and recharge, and, in some cases, wetting fronts from precipitation events during the fall overtook and mixed with infiltration from the previous spring snowmelt. Thus, in thicker unsaturated zones, the volume of water infiltrated was properly simulated using the traditional approach, but the timing was different from simulations that included unsaturated zone flow. Routing of rejected recharge and ground water discharge at land surface to surface water features also provided a better simulation of the observed flow regime in a stream at the basin outlet. These results demonstrate that consideration of flow through the unsaturated zone may be important when simulating transient ground water flow in humid climates with shallow water tables.

Hunt, R.J.; Prudic, D.E.; Walker, J.F.; Anderson, M.P.

2008-01-01

428

HYDRUS-1D Modeling of an Irrigated Agricultural Plot with Application to Aquifer Recharge Estimation  

Technology Transfer Automated Retrieval System (TEKTRAN)

A variety of methods are available for estimating aquifer recharge in semi-arid regions, each with advantages and disadvantages. We are investigating a procedure for estimating recharge in an irrigated basin. The method involves computing irrigation return flows based on HYDRUS-1D modeling of root z...

429

Discrete-storm water-table fluctuation method to estimate episodic recharge.  

PubMed

We have developed a method to identify and quantify recharge episodes, along with their associated infiltration-related inputs, by a consistent, systematic procedure. Our algorithm partitions a time series of water levels into discrete recharge episodes and intervals of no episodic recharge. It correlates each recharge episode with a specific interval of rainfall, so storm characteristics such as intensity and duration can be associated with the amount of recharge that results. To be useful in humid climates, the algorithm evaluates the separability of events, so that those whose recharge cannot be associated with a single storm can be appropriately lumped together. Elements of this method that are subject to subjectivity in the application of hydrologic judgment are values of lag time, fluctuation tolerance, and master recession parameters. Because these are determined once for a given site, they do not contribute subjective influences affecting episode-to-episode comparisons. By centralizing the elements requiring scientific judgment, our method facilitates such comparisons by keeping the most subjective elements openly apparent, making it easy to maintain consistency. If applied to a period of data long enough to include recharge episodes with broadly diverse characteristics, the method has value for predicting how climatic alterations in the distribution of storm intensities and seasonal duration may affect recharge. PMID:24588378

Nimmo, John R; Horowitz, Charles; Mitchell, Lara

2015-03-01

430

USGS Professional Paper 1703--Ground-Water Recharge in the Arid and Semiarid Southwestern United States--  

E-print Network

USGS Professional Paper 1703--Ground-Water Recharge in the Arid and Semiarid Southwestern United, streamflow, and water-table eleva- tions, for example--for calibration and performance testing. Calibration provides initial estimates of the rates and distribu- tion of ground-water recharge, and the calibrated

Binley, Andrew

431

Streamflow, Infiltration, and Ground-Water Recharge at Abo Arroyo, New Mexico  

E-print Network

Streamflow, Infiltration, and Ground-Water Recharge at Abo Arroyo, New Mexico USGS Professional Paper 1703--Ground-Water Recharge in the Arid and Semiarid Southwestern United States-- Chapter D By Amy-fill sediments and separated from the regional water table by an unsaturated zone that reaches 120 meters thick

432

www.VadoseZoneJournal.org | 6622011, Vol. 10 Groundwater Recharge through  

E-print Network

www.VadoseZoneJournal.org | 6622011, Vol. 10 Groundwater Recharge through Vertisols: Irrigated groundwater recharge, including water quantity and quality. Soil core samples (0­11-m depth) from six similar to recent local groundwater Cl- and significantly lower than pore-water Cl- in deep vadose zones

Scanlon, Bridget R.

433

Ground-Water Recharge in the Arid and Semiarid Southwestern United States --  

E-print Network

Ground-Water Recharge in the Arid and Semiarid Southwestern United States -- Climatic and Geologic Framework By David A. Stonestrom and James R. Harrill Abstract Ground-water recharge in the arid focused in time and space. Widespread water-table declines accompanied agricultural development during

434

Historical Groundwater Fluctuation in Suffolk, Virginia Simulated Using Effective Monthly Recharge (Wem) Model  

E-print Network

Historical Groundwater Fluctuation in Suffolk, Virginia Simulated Using Effective Monthly Recharge. The Effective Monthly Recharge (Wem) model generates a synthetic hydrograph of water table elevations (Wem) model. We wanted to calibrate the model using a short portion of a long record of groundwater

Darby, Dennis

435

COMPARATIVE LIFE CYCLE ASSESSMENT OF ALCALINE CELLS AND NI-MH RECHARGEABLE BATTERIES  

E-print Network

Page 1 COMPARATIVE LIFE CYCLE ASSESSMENT OF ALCALINE CELLS AND NI-MH RECHARGEABLE BATTERIES Jean by applying the LCA methodology to evaluate the environmental footprint of alkaline cells and Ni-MH batteries phase. Besides, the emphasis on rechargeable batteries is only justified from an environmental point

Paris-Sud XI, Université de

436

Discrete-storm water-table fluctuation method to estimate episodic recharge.  

USGS Publications Warehouse

We have developed a method to identify and quantify recharge episodes, along with their associated infiltration-related inputs, by a consistent, systematic procedure. Our algorithm partitions a time series of water levels into discrete recharge episodes and intervals of no episodic recharge. It correlates each recharge episode with a specific interval of rainfall, so storm characteristics such as intensity and duration can be associated with the amount of recharge that results. To be useful in humid climates, the algorithm evaluates the separability of events, so that those whose recharge cannot be associated with a single storm can be appropriately lumped together. Elements of this method that are subject to subjectivity in the application of hydrologic judgment are values of lag time, fluctuation tolerance, and master recession parameters. Because these are determined once for a given site, they do not contribute subjective influences affecting episode-to-episode comparisons. By centralizing the elements requiring scientific judgment, our method facilitates such comparisons by keeping the most subjective elements openly apparent, making it easy to maintain consistency. If applied to a period of data long enough to include recharge episodes with broadly diverse characteristics, the method has value for predicting how climatic alterations in the distribution of storm intensities and seasonal duration may affect recharge.

Nimmo, John R.; Horowittz, Charles; Mitchell, Lara

2015-01-01

437

Estimation of recharge from irrigation flows; Analysis of field and laboratory data and modeling.  

Technology Transfer Automated Retrieval System (TEKTRAN)

This work is aimed at quantifying aquifer recharge due to irrigation in the Campo de Cartagena (SE Spain). A study of recharge was conducted on an experiment plot cropped in lettuce and irrigated with a drip system. The physico-chemical and hydraulic properties of the vadose zone were characterized ...

438

A root zone modelling approach to estimating groundwater recharge from irrigated areas  

Microsoft Academic Search

summary In irrigated semi-arid and arid regions, accurate knowledge of groundwater recharge is important for the sustainable management of scarce water resources. The Campo de Cartagena area of southeast Spain is a semi-arid region where irrigation return flow accounts for a substantial portion of recharge. In this study we estimated irrigation return flow using a root zone modelling approach in

Jacinto M. Jiménez-Martínez; Todd H. Skaggs

2009-01-01

439

MODIS-Aided Statewide Net Groundwater-Recharge Estimation in Nebraska  

E-print Network

MODIS-Aided Statewide Net Groundwater-Recharge Estimation in Nebraska by Jozsef Szilagyi1-function-transformed groundwater vulnerability DRASTIC-code values. Statewide mean annual net recharge became about 29 mm (i.e., 5 by declining groundwater levels due to large-scale irrigation are found in the south-western region

Szilagyi, Jozsef

440

Hydropedologic Analysis of Ground-Water Recharge at the Field Scale  

Technology Transfer Automated Retrieval System (TEKTRAN)

Estimating ground-water recharge is an important element in water resources characterization, vulnerability assessment, and utilization. Contaminant sources often occur in the unsaturated zone where ground-water recharge may mobilize it to migrate into a water table aquifer. Cumulative soil water...