These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

WATER TREATMENT BY HETEROGENEOUS PHOTOCATALYSIS AN OVERVIEW1  

Microsoft Academic Search

Photocatalysis process, as an environmental application is a relatively novel subject with tremendous potential in the near future. This paper describes the basics of heterogeneous photocatalysis, mainly on TiO2 and the application of photocatalytic processes to water purification and treatment. The paper also reviews more than 50 references covering the wide scale of heterogeneous water phase applications. Finally, a short

Radwan A. Al-Rasheed

2

Plasmonic photocatalysis.  

PubMed

Plasmonic photocatalysis has recently facilitated the rapid progress in enhancing photocatalytic efficiency under visible light irradiation, increasing the prospect of using sunlight for environmental and energy applications such as wastewater treatment, water splitting and carbon dioxide reduction. Plasmonic photocatalysis makes use of noble metal nanoparticles dispersed into semiconductor photocatalysts and possesses two prominent features-a Schottky junction and localized surface plasmonic resonance (LSPR). The former is of benefit to charge separation and transfer whereas the latter contributes to the strong absorption of visible light and the excitation of active charge carriers. This article aims to provide a systematic study of the fundamental physical mechanisms of plasmonic photocatalysis and to rationalize many experimental observations. In particular, we show that LSPR could boost the generation of electrons and holes in semiconductor photocatalysts through two different effects-the LSPR sensitization effect and the LSPR-powered bandgap breaking effect. By classifying the plasmonic photocatalytic systems in terms of their contact form and irradiation state, we show that the enhancement effects on different properties of photocatalysis can be well-explained and systematized. Moreover, we identify popular material systems of plasmonic photocatalysis that have shown excellent performance and elucidate their key features in the context of our proposed mechanisms and classifications. PMID:23455654

Zhang, Xuming; Chen, Yu Lim; Liu, Ru-Shi; Tsai, Din Ping

2013-04-01

3

Electrocatalysis in water electrolysis with solid polymer electrolyte  

Microsoft Academic Search

Powders of IrO2 were used as anode catalysts in water electrolysis cells with solid polymer electrolyte (SPE). The catalyst was prepared by a pyrolysis process in a nitrate melt at 340°C and then annealed at different temperatures from 440 to 540°C. The catalyst materials were applied to an electrode membrane assembly (MEA) and studied in situ in an electrolysis cell

Egil Rasten; Georg Hagen; Reidar Tunold

2003-01-01

4

Water oxidation electrocatalysis by a zeolitic imidazolate framework  

NASA Astrophysics Data System (ADS)

The search for efficient water oxidation catalysts (WOCs) is of paramount importance in energy and environmental fields, but there exists no good non-noble catalyst that works under acidic and alkaline conditions. Intensive investigations have recently focused on cobalt based complex/solid catalysts. Here, we have introduced a new type of cobalt-based WOC made of metal-organic frameworks where the redox function of cobalt centres was modified by imidazolate linkers for facilitating the proton transfer process. This cobalt-containing zeolitic imidazolate framework (Co-ZIF-9) has been demonstrated for the first time to electrocatalyze the oxygen evolution reaction in a wide pH range. The catalyst was found by theoretical calculation to be capable of activating the water molecule via binding the OH-group to the metal sites with low activation barriers, while the eliminated proton was accepted by the nearby benzimidazolate motifs. This allows Co-ZIF-9 to work effectively for the electrochemical oxygen-evolution reaction.The search for efficient water oxidation catalysts (WOCs) is of paramount importance in energy and environmental fields, but there exists no good non-noble catalyst that works under acidic and alkaline conditions. Intensive investigations have recently focused on cobalt based complex/solid catalysts. Here, we have introduced a new type of cobalt-based WOC made of metal-organic frameworks where the redox function of cobalt centres was modified by imidazolate linkers for facilitating the proton transfer process. This cobalt-containing zeolitic imidazolate framework (Co-ZIF-9) has been demonstrated for the first time to electrocatalyze the oxygen evolution reaction in a wide pH range. The catalyst was found by theoretical calculation to be capable of activating the water molecule via binding the OH-group to the metal sites with low activation barriers, while the eliminated proton was accepted by the nearby benzimidazolate motifs. This allows Co-ZIF-9 to work effectively for the electrochemical oxygen-evolution reaction. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr02399d

Wang, Sibo; Hou, Yidong; Lin, Sen; Wang, Xinchen

2014-08-01

5

Heterogeneous photocatalysis of moxifloxacin in water: Chemical transformation and ecotoxicity.  

PubMed

This work provides new insights on the impact of TiO2/UV catalyzed chemical transformation of moxifloxacin on ecotoxicity effects towards the green alga Pseudokirchneriella subcapitata. The moxifloxacin median effect concentration (EC-50=0.78 [0.56, 1.09] mgL(-1)), determined in accordance to the OECD 72-h growth inhibition test guideline, was 7 times lower than that of the older and widely used fluoroquinolone ciprofloxacin (EC-50=5.57 [4.86, 6.38] mgL(-1)). Applying heterogeneous photocatalysis as an advanced oxidation technique to degrade moxifloxacin in aqueous solution decreased the average growth inhibition from 72% to 14% after 150min of treatment. No significant carbon mineralization was observed and liquid chromatography mass spectrometry analysis revealed the formation of 13 degradation products for which a chemical structure could be proposed based on accurate mass determination. Combined chemical and ecotoxicological analysis showed that as long as moxifloxacin is present in the reaction solution, it is the main compound affecting algal growth inhibition. However, also the contribution of the degradation products to the observed ecotoxicity cannot be neglected. Photocatalytically induced modifications of moxifloxacin mainly occur at the diazobicyclo-substituent as ring opening, oxidation into carbonyl groups, and hydroxylation. This results into the formation of more hydrophilic compounds with a decreased biological activity compared with moxifloxacin. The change in lipophilicity, and possibly a modified acid-base speciation, most probably also affect the cell membrane permeation of the degradation products, which might be another factor explaining the observed lower residual ecotoxicity of the photocatalytically treated reaction solutions. PMID:24735961

Van Doorslaer, Xander; Haylamicheal, Israel Deneke; Dewulf, Jo; Van Langenhove, Herman; Janssen, Colin R; Demeestere, Kristof

2015-01-01

6

Fabrication of transparent-conducting-oxide-coated inverse opals as mesostructured architectures for electrocatalysis applications: a case study with NiO.  

PubMed

Highly ordered, and conductive inverse opal arrays were made with silica and subsequently coated with tin-doped indium oxide (ITO) via atomic layer deposition (ALD). We demonstrate the utility of the resulting mesostructured electrodes by further coating them with nickel oxide via ALD. The NiO-coated arrays are capable of efficiently electrochemically evolving oxygen from water. These modular, crack-free, transparent, high surface area, and conducting structures show promise for many applications including electrocatalysis, photocatalysis, and dye-sensitized solar cells. PMID:25033088

Williams, Vennesa O; DeMarco, Erica J; Katz, Michael J; Libera, Joseph A; Riha, Shannon C; Kim, Dong Wook; Avila, Jason R; Martinson, Alex B F; Elam, Jeffrey W; Pellin, Michael J; Farha, Omar K; Hupp, Joseph T

2014-08-13

7

Size-dependent subnanometer Pd cluster (Pd4, Pd6, and Pd17) water oxidation electrocatalysis.  

PubMed

Water oxidation is a key catalytic step for electrical fuel generation. Recently, significant progress has been made in synthesizing electrocatalytic materials with reduced overpotentials and increased turnover rates, both key parameters enabling commercial use in electrolysis or solar to fuels applications. The complexity of both the catalytic materials and the water oxidation reaction makes understanding the catalytic site critical to improving the process. Here we study water oxidation in alkaline conditions using size-selected clusters of Pd to probe the relationship between cluster size and the water oxidation reaction. We find that Pd4 shows no reaction, while Pd6 and Pd17 deposited clusters are among the most active (in terms of turnover rate per Pd atom) catalysts known. Theoretical calculations suggest that this striking difference may be a demonstration that bridging Pd-Pd sites (which are only present in three-dimensional clusters) are active for the oxygen evolution reaction in Pd6O6. The ability to experimentally synthesize size-specific clusters allows direct comparison to this theory. The support electrode for these investigations is ultrananocrystalline diamond (UNCD). This material is thin enough to be electrically conducting and is chemically/electrochemically very stable. Even under the harsh experimental conditions (basic, high potential) typically employed for water oxidation catalysts, UNCD demonstrates a very wide potential electrochemical working window and shows only minor evidence of reaction. The system (soft-landed Pd4, Pd6, or Pd17 clusters on a UNCD Si-coated electrode) shows stable electrochemical potentials over several cycles, and synchrotron studies of the electrodes show no evidence for evolution or dissolution of either the electrode material or the clusters. PMID:23799858

Kwon, Gihan; Ferguson, Glen A; Heard, Christopher J; Tyo, Eric C; Yin, Chunrong; DeBartolo, Janae; Seifert, Sönke; Winans, Randall E; Kropf, A Jeremy; Greeley, Jeffrey; Johnston, Roy L; Curtiss, Larry A; Pellin, Michael J; Vajda, Stefan

2013-07-23

8

Electrocatalysis for oxygen electrodes in fuel cells and water electrolyzers for space applications  

NASA Technical Reports Server (NTRS)

In most instances separate electrocatalysts are needed to promote the reduction of O2 in the fuel cell mode and to generate O2 in the energy storage-water electrolysis mode in aqueous electrochemical systems operating at low and moderate temperatures (T greater than or equal to 200 C). Interesting exceptions are the lead and bismuth ruthenate pyrochlores in alkaline electrolytes. These catalysts on high area carbon supports have high catalytic activity for both O2 reduction and generation. Rotating ring-disk electrode measurements provide evidence that the O2 reduction proceeds by a parallel four-electron pathway. The ruthenates can also be used as self-supported catalysts to avoid the problems associated with carbon oxidation, but the electrode performance so far achieved in the research at Case Western Reserve University (CWRU) is considerably less. At the potentials involved in the anodic mode the ruthenate pyrochlores have substantial equilibrium solubility in concentrated alkaline electrolyte. This results in the loss of catalyst into the bulk solution and a decline in catalytic activity. Furthermore, the hydrogen generation counter electrode may become contaminated with reduction products from the pyrochlores (lead, ruthenium).

Prakash, Jai; Tryk, Donald; Yeager, Ernest

1989-01-01

9

Electrocatalysis in DNA Sensors.  

PubMed

Electrocatalysis is often thought of solely in the inorganic realm, most often applied to energy conversion in fuel cells. However, the ever-growing field of bioelectrocatalysis has made great strides in advancing technology for both biofuel cells as well as biological detection platforms. Within the context of bioelectrocatalytic detection systems, DNA-based platforms are especially prevalent. One subset of these platforms, the one we have developed, takes advantage of the inherent charge transport properties of DNA. Electrocatalysis coupled with DNA-mediated charge transport has enabled specific and sensitive detection of lesions, mismatches and DNA-binding proteins. Even greater signal amplification from these platforms is now being achieved through the incorporation of a secondary electrode to the platform both for patterning DNA arrays and for detection. Here, we describe the evolution of this new DNA sensor technology. PMID:25435647

Furst, Ariel; Hill, Michael G; Barton, Jacqueline K

2014-12-14

10

Photocatalysis Using Semiconductor Nanoclusters  

SciTech Connect

We report on experiments using nanosize MoS{sub 2} to photo-oxidize organic pollutants in water using visible light as the energy source. We have demonstrated that we can vary the redox potentials and absorbance characteristics of these small semiconductors by adjusting their size, and our studies of the photooxidation of organic molecules have revealed that the rate of oxidation increases with increasing bandgap (i.e. more positive valence band and more negative conduction band potentials). Because these photocatalysis reactions can be performed with the nanoclusters fully dispersed and stable in solution, liquid chromatography can be used to determine both the intermediate reaction products and the state of the nanoclusters during the reaction. We have demonstrated that the MoS{sub 2} nanoclusters remain unchanged during the photooxidation process by this technique. We also report on studies of MoS{sub 2} nanoclusters deposited on TiO{sub 2} powder.

Thurston, T.R.; Wilcoxon,J.P.

1999-01-21

11

TREATMENT OF METHYL TERT-BUTYL ETHER CONTAMINATED WATER USING PHOTOCATALYSIS  

EPA Science Inventory

The feasibility of photo-oxidation treatment of methyl tert-butyl ether (MTBE) in water was investigated in three ways, 1) using a slurry falling film photo-reactor, 2) a batch solar reactor system, and 3) a combination of air-stripping and gas phase photooxidation system. MTBE-c...

12

Removal of 2-chlorophenol from water by adsorption combined with TiO 2 photocatalysis  

Microsoft Academic Search

The results of a laboratory-scale study of an environmentally friendly water treatment method is presented, where the organic model pollutant 2-chlorophenol (2-CP) was first adsorbed and then removed by a direct photolytic or heterogeneous photocatalytic process. The adsorbent was an organically treated (with hexadecylpyridinium chloride) clay mineral (montmorillonite), and the photocatalyst was Degussa P25. The total organic carbon and total

István Ilisz; András Dombi; Károly Mogyorósi; András Farkas; Imre Dékány

2002-01-01

13

Enhanced removal of dichloroacetonitrile from drinking water by the combination of solar-photocatalysis and ozonation.  

PubMed

In this study, the photocatalytic ozonation process using either UV lamps with a wavelength close to a solar wavelength (UVsolar) or natural solar light was established to study the effects of the major operating parameters on the removal of a toxic disinfection by-product (DBP), dichloroacetonitrile (DCAN), from drinking water. Based on the test results of a bench system, the UVsolar/TiO2/O3 process had the highest DCAN-removal rate among the advanced oxidation processes (AOPs). The optimal TiO2 and ozone doses were 1gL(-1) and 1.13gL(-1)h(-1), respectively, while room temperature (20°C) produced the highest rate constant in the kinetic tests. The kinetic rate constants linearly increased when the UVsolar intensity increased in the range 4.6-25Wm(-2); however, it increased less at intensities higher than 25Wm(-2). The test results of the outdoor system showed that the solar/TiO2/O3 process provided complete removal of DCAN that was two times faster and had about 4.6 times higher energy efficiency than with solar/TiO2. As a green oxidation technique, solar photocatalytic ozonation could be a good alternative for treating recalcitrant and toxic organic pollutants, because it has high oxidation potential and low energy consumption compared to conventional AOPs. PMID:24125715

Shin, Donghoon; Jang, Min; Cui, Mingcan; Na, Seungmin; Khim, Jeehyeong

2013-11-01

14

Titanium dioxide photocatalysis  

Microsoft Academic Search

Scientific studies on photocatalysis started about two and a half decades ago. Titanium dioxide (TiO2), which is one of the most basic materials in our daily life, has emerged as an excellent photocatalyst material for environmental purification. In this review, current progress in the area of TiO2 photocatalysis, mainly photocatalytic air purification, sterilization and cancer therapy are discussed together with

Akira Fujishima; Tata N. Rao; Donald A. Tryk

2000-01-01

15

Studies of the pathways open to copper water oxidation catalysts containing proximal hydroxy groups during basic electrocatalysis.  

PubMed

Water oxidation can lead to a sustainable source of energy, but for water oxidation catalysts to be economical they must use earth abundant metals. We report here 2:1 6,6'-dihydroxybipyridine (6,6'-dhbp)/copper complexes that are capable of electrocatalytic water oxidation in aqueous base (pH = 10-14). Two crystal structures of the complex that contains 6,6'-dhbp and copper(II) in a ratio of 2:1 (complex 1) are presented at different protonation states. The thermodynamic acid dissociation constants were measured for complex 1, and these show that the complex is fully deprotonated above pH = 8.3 (i.e., under water oxidation conditions). CW-EPR, ENDOR, and HYSCORE spectroscopy confirmed that the 6,6'-dhbp ligand is bound to the copper ion over a wide pH range which shows how pH influences precatalyst structure. Additional copper(II) complexes were synthesized from the ligands 4,4'-dhbp (complex 2) and 6,6'-dimethoxybipyridine (complexes 3 and 4). A zinc complex of 6,6'-dhbp was also synthesized (complex 5). Crystal structures are reported for 1 (in two protonation states), 3, 4, and 5. Water oxidation studies using several of the above compounds (1, 2, 4, and 5) at pH = 12.6 have illustrated that both copper and proximal OH groups are necessary for water oxidation at a low overpotential. Our most active catalyst 1 was found to have an overpotential of 477 mV for water oxidation at a moderate rate of kcat = 0.356 s(-1) with a competing irreversible oxidation event at a rate of 1.082 s(-1). Furthermore, our combined work supports previous observations in which OH/O(-) groups on the bipyridine rings can hydrogen bond with metal bound substrate, support unusual binding modes, and potentially facilitate proton coupled electron transfer. PMID:25427106

Gerlach, Deidra L; Bhagan, Salome; Cruce, Alex A; Burks, Dalton B; Nieto, Ismael; Truong, Hai T; Kelley, Steven P; Herbst-Gervasoni, Corey J; Jernigan, Katherine L; Bowman, Michael K; Pan, Shanlin; Zeller, Matthias; Papish, Elizabeth T

2014-12-15

16

Single-crystal-like NiO colloidal nanocrystal-aggregated microspheres with mesoporous structure: Synthesis and enhanced electrochemistry, photocatalysis and water treatment properties  

SciTech Connect

A new microwave-assisted hydrothermal synthetic route based on the self-assembly and subsequently controlled thermal decomposition process is proposed to fabricate nickel oxide colloidal nanocrystal aggregated microspheres (CNAMs) with mesoporous structure. XRD, EDS, SEM, TEM. FTIR, and N{sub 2} adsorption and desorption isotherm techniques are employed for morphology and structure characterizations. The as-prepared nickel oxide CNAMs, which has a high surface area (234 m{sup 2}/g) with narrow pore distribution at around 3.25 nm, are composed of numerous hexagonal mesoporous nanocrystals of approximately 50–60 nm in size, and present a single-crystal-like characteristic. The experimental results also demonstrated that the CNAMs showed outstanding performance in electrochemistry, photocatalysis and waste water treatment due to their special hierarchical and mesoporous structure, presenting the promising candidate for catalysis and catalysis support materials. - Graphical abstract: CNAMs with mesoporous structure synthesized via a simple microwave-assisted hydrothermal method was applied in electrochemistry and catalysis and exhibited enhanced performance. Display Omitted - Highlights: • CNAMs with mesoporous structure are achieved via a simple microwave-assisted hydrothermal method. • Morphology, structure and pore distribution of sample particles is specifically controlled. • The samples show enhanced properties in electrochemistry and catalysis due to hierarchical structure.

Suo, Zhirong [Analytical and Testing Center, Southwest University of Science and Technology, Mianyang 621010 (China); Dong, Xiaonan [School of Materials Science and Engineering, Shaanxi University of Science and Technology, Xi’an 710021 (China); Liu, Hui, E-mail: liuhui@sust.edu.cn [School of Materials Science and Engineering, Shaanxi University of Science and Technology, Xi’an 710021 (China)

2013-10-15

17

DNA sensing by electrocatalysis with hemoglobin.  

PubMed

Electrocatalysis offers a means of electrochemical signal amplification, yet in DNA-based sensors, electrocatalysis has required high-density DNA films and strict assembly and passivation conditions. Here, we describe the use of hemoglobin as a robust and effective electron sink for electrocatalysis in DNA sensing on low-density DNA films. Protein shielding of the heme redox center minimizes direct reduction at the electrode surface and permits assays on low-density DNA films. Electrocatalysis with methylene blue that is covalently tethered to the DNA by a flexible alkyl chain linkage allows for efficient interactions with both the base stack and hemoglobin. Consistent suppression of the redox signal upon incorporation of a single cytosine-adenine (CA) mismatch in the DNA oligomer demonstrates that both the unamplified and the electrocatalytically amplified redox signals are generated through DNA-mediated charge transport. Electrocatalysis with hemoglobin is robust: It is stable to pH and temperature variations. The utility and applicability of electrocatalysis with hemoglobin is demonstrated through restriction enzyme detection, and an enhancement in sensitivity permits femtomole DNA sampling. PMID:22733728

Pheeney, Catrina G; Guerra, Luis F; Barton, Jacqueline K

2012-07-17

18

DNA sensing by electrocatalysis with hemoglobin  

PubMed Central

Electrocatalysis offers a means of electrochemical signal amplification, yet in DNA-based sensors, electrocatalysis has required high-density DNA films and strict assembly and passivation conditions. Here, we describe the use of hemoglobin as a robust and effective electron sink for electrocatalysis in DNA sensing on low-density DNA films. Protein shielding of the heme redox center minimizes direct reduction at the electrode surface and permits assays on low-density DNA films. Electrocatalysis with methylene blue that is covalently tethered to the DNA by a flexible alkyl chain linkage allows for efficient interactions with both the base stack and hemoglobin. Consistent suppression of the redox signal upon incorporation of a single cytosine-adenine (CA) mismatch in the DNA oligomer demonstrates that both the unamplified and the electrocatalytically amplified redox signals are generated through DNA-mediated charge transport. Electrocatalysis with hemoglobin is robust: It is stable to pH and temperature variations. The utility and applicability of electrocatalysis with hemoglobin is demonstrated through restriction enzyme detection, and an enhancement in sensitivity permits femtomole DNA sampling. PMID:22733728

Pheeney, Catrina G.; Guerra, Luis F.; Barton, Jacqueline K.

2012-01-01

19

Plasmon-enhanced UV photocatalysis  

SciTech Connect

We report plasmonic nanoparticle enhanced photocatalysis on titanium dioxide (TiO{sub 2}) in the deep-UV range. Aluminum (Al) nanoparticles fabricated on TiO{sub 2} film increases the reaction rate of photocatalysis by factors as high as 14 under UV irradiation in the range of 260–340?nm. The reaction efficiency has been determined by measuring the decolorization rate of methylene blue applied on the TiO{sub 2} substrate. The enhancement of photocatalysis shows particle size and excitation wavelength dependence, which can be explained by the surface plasmon resonance of Al nanoparticles.

Honda, Mitsuhiro; Saito, Yuika, E-mail: yuika@ap.eng.osaka-u.ac.jp; Kawata, Satoshi [Department of Applied Physics, Osaka University, Suita, Osaka 565-0871 (Japan); Kumamoto, Yasuaki [Nanophotonics Laboratory, RIKEN, Wako, Saitama 351-0198 (Japan); Taguchi, Atsushi [Nanophotonics Laboratory, RIKEN, Wako, Saitama 351-0198 (Japan); Department of Mechanical Systems Engineering, School of Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588 (Japan)

2014-02-10

20

Role of Nanoparticles in Photocatalysis  

Microsoft Academic Search

The aim of this review paper is to give an overview of the development and implications of nanotechnology in photocatalysis. The topics covered include a detailed look at the unique properties of nanoparticles and their relation to photocatalytic properties. Current applications of and research into the use of nanoparticles as photocatalysts has also been reviewed. Also covered is the utilization

D. Beydoun; R. Amal; G. Low; S. McEvoy

1999-01-01

21

Single-site copper(II) water oxidation electrocatalysis: rate enhancements with HPO?²? as a proton acceptor at pH?8.  

PubMed

The complex Cu(II)(Py3P) (1) is an electrocatalyst for water oxidation to dioxygen in H2PO4(-)/HPO4(2-) buffered aqueous solutions. Controlled potential electrolysis experiments with 1 at pH?8.0 at an applied potential of 1.40?V versus the normal hydrogen electrode resulted in the formation of dioxygen (84% Faradaic yield) through multiple catalyst turnovers with minimal catalyst deactivation. The results of an electrochemical kinetics study point to a single-site mechanism for water oxidation catalysis with involvement of phosphate buffer anions either through atom-proton transfer in a rate-limiting O-O bond-forming step with HPO4(2-) as the acceptor base or by concerted electron-proton transfer with electron transfer to the electrode and proton transfer to the HPO4(2-) base. PMID:25243584

Coggins, Michael K; Zhang, Ming-Tian; Chen, Zuofeng; Song, Na; Meyer, Thomas J

2014-11-01

22

Combine electrochemistry with photocatalysis  

Microsoft Academic Search

Because a substantial percentage of colorant is lost during the dyeing process, remediation efforts have largely been focused on removing these dyes from the wastewater effluents of textile mills and other industrial colorant users. Incomplete decolorization of the effluent before discharge shifts the burden of treatment downstream. In publicly owned water treatment facilities, these dyes often end up as sludges

K. Vinodgopal; P. V. Kamat

1996-01-01

23

Metal-organic frameworks for artificial photosynthesis and photocatalysis.  

PubMed

Solar energy is an alternative, sustainable energy source for mankind. Finding a convenient way to convert sunlight energy into chemical energy is a key step towards realizing large-scale solar energy utilization. Owing to their structural regularity and synthetic tunability, metal-organic frameworks (MOFs) provide an interesting platform to hierarchically organize light-harvesting antennae and catalytic centers to achieve solar energy conversion. Such photo-driven catalytic processes not only play a critical role in the solar to chemical energy conversion scheme, but also provide a novel methodology for the synthesis of fine chemicals. In this review, we summarize the fundamental principles of energy transfer and photocatalysis and provide an overview of the latest progress in energy transfer, light-harvesting, photocatalytic proton and CO2 reduction, and water oxidation using MOFs. The applications of MOFs in organic photocatalysis and degradation of model organic pollutants are also discussed. PMID:24769551

Zhang, Teng; Lin, Wenbin

2014-08-21

24

Combine electrochemistry with photocatalysis  

SciTech Connect

Because a substantial percentage of colorant is lost during the dyeing process, remediation efforts have largely been focused on removing these dyes from the wastewater effluents of textile mills and other industrial colorant users. Incomplete decolorization of the effluent before discharge shifts the burden of treatment downstream. In publicly owned water treatment facilities, these dyes often end up as sludges that are dewatered and eventually deposited in landfills. There is a substantial economic impetus to develop a flow reactor to be used onstream by mills to treat colorant effluent and recycle the water. The authors have developed a photocatalytic approach using semiconductors for degrading several azo dyes. They recently found that deposition of semiconductor nanoclusters on a conducting glass surface provides a convenient way to manipulate the photocatalytic reaction by electrochemical methods. The thin semiconductor particulate film can be used as a photosensitive electrode in an electrochemical cell. The paper describes electrode preparation, the photoelectrochemical properties of TiO{sub 2} and SnO{sub 2}, reaction mechanism, and composite semiconductor films.

Vinodgopal, K. [Indiana Univ. Northwest, Gary, IN (United States); Kamat, P.V. [Univ. of Notre Dame, IN (United States)

1996-04-01

25

HIgh Temperature Photocatalysis over Semiconductors  

NASA Astrophysics Data System (ADS)

Due in large part to in prevalence of solar energy, increasing demand of energy production (from all sources), and the uncertain future of petroleum energy feedstocks, solar energy harvesting and other photochemical systems will play a major role in the developing energy market. This dissertation focuses on a novel photochemical reaction process: high temperature photocatalysis (i.e., photocatalysis conducted above ambient temperatures, T ? 100°C). The overarching hypothesis of this process is that photo-generated charge carriers are able to constructively participate in thermo-catalytic chemical reactions, thereby increasing catalytic rates at one temperature, or maintaining catalytic rates at lower temperatures. The photocatalytic oxidation of carbon deposits in an operational hydrocarbon reformer is one envisioned application of high temperature photocatalysis. Carbon build-up during hydrocarbon reforming results in catalyst deactivation, in the worst cases, this was shown to happen in a period of minutes with a liquid hydrocarbon. In the presence of steam, oxygen, and above-ambient temperatures, carbonaceous deposits were photocatalytically oxidized over very long periods (t ? 24 hours). This initial experiment exemplified the necessity of a fundamental assessment of high temperature photocatalytic activity. Fundamental understanding of the mechanisms that affect photocatalytic activity as a function of temperatures was achieved using an ethylene photocatalytic oxidation probe reaction. Maximum ethylene photocatalytic oxidation rates were observed between 100 °C and 200 °C; the maximum photocatalytic rates were approximately a factor of 2 larger than photocatalytic rates at ambient temperatures. The loss of photocatalytic activity at temperatures above 200 °C is due to a non-radiative multi-phonon recombination mechanism. Further, it was shown that the fundamental rate of recombination (as a function of temperature) can be effectively modeled as a temperature-dependent quantum efficiency term, and is directly driven by bulk photocatalyst crystal parameters: maximum phonon energy and the number of phonons allowed per unit cell. This analysis extends to multiple photocatalysts and can explain experimental observations of photocatalytic oxidation rates with varied reactant concentrations. Lastly, this dissertation applies this knowledge to a thermo-catalytic reaction (CO-oxidation) using a Au/TiO 2 catalyst. The combined photo/thereto-catalytic reaction showed a 10-25% increase in CO conversion during a temperature programmed reaction experiment.

Westrich, Thomas A.

26

Electrocatalysis issues in polymer electrolyte fuel cells  

SciTech Connect

Various electrocatalysis issues of impotance to low platinum loading polymer electrolyte fuel cells (PEFCs) are discussed. Thin film catalyst layer assemblies are used to investigate the effects of CO and CO[sub 2] on the anode as well as efforts to restore performance by oxygen bleeding into the anode feedstream. These electrodes behave differently than ionomer-impregnated E-TEK electrodes because the extra, exposed Pt in the latter case. The tolerance of Pt-Ru alloy thin film anodes to CO and CO[sub 2] are also evaluated. Thin film electrodes are also used to study Pt particle growth in aged electrodes as well as particle size effects on specific activity.

Wilson, M.S.; Derouin, C.R.; Valerio, J.A.; Gottesfeld, S.

1993-01-01

27

TiO 2 photocatalysis and related surface phenomena  

NASA Astrophysics Data System (ADS)

The field of photocatalysis can be traced back more than 80 years to early observations of the chalking of titania-based paints and to studies of the darkening of metal oxides in contact with organic compounds in sunlight. During the past 20 years, it has become an extremely well researched field due to practical interest in air and water remediation, self-cleaning surfaces, and self-sterilizing surfaces. During the same period, there has also been a strong effort to use photocatalysis for light-assisted production of hydrogen. The fundamental aspects of photocatalysis on the most studied photocatalyst, titania, are still being actively researched and have recently become quite well understood. The mechanisms by which certain types of organic compounds are decomposed completely to carbon dioxide and water, for example, have been delineated. However, certain aspects, such as the photo-induced wetting phenomenon, remain controversial, with some groups maintaining that the effect is a simple one in which organic contaminants are decomposed, while other groups maintain that there are additional effects in which the intrinsic surface properties are modified by light. During the past several years, powerful tools such as surface spectroscopic techniques and scanning probe techniques performed on single crystals in ultra-high vacuum, and ultrafast pulsed laser spectroscopic techniques have been brought to bear on these problems, and new insights have become possible. Quantum chemical calculations have also provided new insights. New materials have recently been developed based on titania, and the sensitivity to visible light has improved. The new information available is staggering, but we hope to offer an overview of some of the recent highlights, as well as to review some of the origins and indicate some possible new directions.

Fujishima, Akira; Zhang, Xintong; Tryk, Donald A.

2008-12-01

28

HETEROGENOUS PHOTOCATALYSIS ON AEROSOL PROCESSED NANOSTRUCTURED TITANIA PARTICLES: ROLE OF PARTICLE SIZE  

EPA Science Inventory

Heterogenous photocatalysis with TiO2 has been extensively investigated as a method to oxidize organic pollutants in water and air, including phenols, chlorinated hydrocarbons, and other hydrocarbons. In addition, the use of titanium dioxide as a photocatalyst has also been demon...

29

REMOVAL OF METHYL TERTIARY BUTYL ETHER (MTBE) FROM GROUNDWATER USING PHOTOCATALYSIS  

EPA Science Inventory

The potential of photocatalysis was determined for treating MTBE-contaminated drinking water supplies. Two liquid-phase systems, a falling film reactor, and a solar degradation system, are being evaluated. We are also conducting a gas-phase treatment method to simulate an integra...

30

Titania carbon nanotube composites for enhanced photocatalysis  

NASA Astrophysics Data System (ADS)

Photocatalytic composites have been used for the past few decades in a wide range of applications. The most common application is the purification of air and water by removing toxic compounds. There is limited use however towards biocidal applications. Despite their high efficiency, photocatalytic materials are not comparable to the effectiveness of conventional biocidal compounds such as chlorine and alcoholic disinfectants. On the other hand, nearly a decade ago with the discovery of the carbon nanotubes a new vibrant scientific field emerged. Nanotubes are unique structures of carbon that posse amazing electrical, mechanical and thermal properties. In this research carbon nanotubes are used as photocatalytic enhancers. They were coated with anatase titania to form a composite material. Two different types of nanotubes (metallic versus non-metallic) were used and the photocatalytic activity was measured. The metallic tubes demonstrated exceptional photocatalytic properties, while non-metallic tubes had low photocatalytic efficiency. The reason for that difference was investigated and was the major focus of this research. The research concluded that the reasons for the high efficiency of the carbon nanotubes were (i) the metallic nature of the tubes and (ii) the possible bond between the titania coating and the underlying graphite layers (C-O-Ti). Since both composites had the same indications regarding the C-O-Ti bond, the metallic nature of the carbon nanotubes is believed to be the most dominant factor contributing to the enhancement of the photocatalysis. The composite material may have other potential applications such as for sensing and photovoltaic uses.

Pyrgiotakis, Georgios

31

Electrocatalysis Breakout Session ANODE (H2//O2/Air)  

E-print Network

. Durability ­ Role of oxygen crossover and ionomer/membrane stability at the anode interface. ­ Other density are not necessarily the best conditions for CO2 selectivity ­ Effect of temperature ­ Effect) and Electrocatalysis (non availability of OH- species at the interface). ­ Effect of temperature ­ is there a sweet

32

Combination of ozonation and photocatalysis for purification of aqueous effluents containing formic acid as probe pollutant and bromide ion.  

PubMed

The treatment by advanced oxidation processes (AOPs) of waters contaminated by organic pollutants and containing also innocuous bromide ions may generate bromate ions as a co-product. In the present work heterogeneous photocatalysis and ozonation have individually been applied and in combination (integrated process) to degrade the organic compounds in water containing also bromide anions. The results show that: i) the sole photocatalysis does not produce bromate ions and in the case of its presence, it is able to reduce bromate to innocuous bromide ions; ii) the integration of photocatalysis and ozonation synergistically enhances the oxidation capabilities; and iii) in the integrated process bromate ions are not produced as long as some oxidizable organics are present. PMID:24374130

Parrino, F; Camera-Roda, G; Loddo, V; Palmisano, G; Augugliaro, V

2014-03-01

33

Thickness-Controlled Graphene Hybrid Interface for Highly Enhanced Photocatalysis.  

E-print Network

??Graphene has been widely studied in hybrid nanocomposites catalyst because of its unique chemical and electrical properties. However, the enhancement mechanisms in photocatalysis of graphene… (more)

Kuo, Cheng-Chi

2014-01-01

34

Electrocatalysis: A direct alcohol fuel cell and surface science perspective  

SciTech Connect

In this report, we discuss some of the advances in surface science and theory that have ena bled a more detailed understanding of the mechanisms that govern the electrocatalysis.More specifically, we examine in detail the electrooxidation ofC1 and Cz alcohol molecules in both acidic and basic media. A combination of detailed in situ spectroscopic measurements along with density functional theory calculations have helped to establish the mechanisms that control the reaction paths and the innuence of acidic and alkaline media. We discuss some of the synergies and differences between electrocatalysis and aqueous phase heterogeneous catalysis.Such analyses begin to establish a common language and framework by which to compare as well as advance both fields.

Braunchweig, B [University of Illinois, Urbana-Champaign; Neurock, Matthew [University of Virginia; Wieckowski, A. [University of Illinois, Urbana-Champaign; Hibbitts, David D [ORNL

2012-01-01

35

Studies on degradation of glyphosate by several oxidative chemical processes: Ozonation, photolysis and heterogeneous photocatalysis  

Microsoft Academic Search

Several different Advanced Oxidation Processes (AOPs) including ozonation at pH 6.5 and 10, photolysis and heterogeneous photocatalysis using TiO2 as semiconductor and dissolved oxygen as electron acceptor were applied to study the degradation of glyphosate (N-phosphonomethyl glycine) in water. The degree of glyphosate degradation, the reactions kinetic and the formation of the major metabolite, aminomethyl phosphonic acid (AMPA), were evaluated.

Marcia R. Assalin; Sandra G. De Moraes; Sonia C. N. Queiroz; Vera L. Ferracini; Nelson Duran

2009-01-01

36

Screened hybrid density functional study on Sr2Nb2O7 for visible light photocatalysis  

NASA Astrophysics Data System (ADS)

The electronic structure of pure Sr2Nb2O7 and its electronic band position are being aligned with respect to the water oxidation/reduction potential level using hybrid functional (HSE06) theory. The experimental band gap (3.90 eV) of pure Sr2Nb2O7 can be reproduced (3.92 eV) using this level of theory. The cationic-anionic co-doping (Mo-N) in layered perovskite Sr2Nb2O7 structure reduces the band gap significantly, and its electronic band position is excellent for the visible-light photocatalysis. The respective cationic and anionic mono-doped systems create an occupied or unoccupied impurity states in the band gap, which can reduce the efficiency of the photocatalysis.

Nisar, J.; Pathak, B.; Ahuja, R.

2012-04-01

37

Laser Raman Spectroscopy in studies of corrosion and electrocatalysis  

SciTech Connect

Laser Raman Spectroscopy (LRS) has become an important tool for the in-situ structural study of electrochemical systems and processes in recent years. Following a brief introduction of the experimental techniques involved in applying LRS to electrochemical systems, we survey the literature for examples of studies in the inhibition of electrode reactions by surface films (e.g., corrosion and passivation phenomena) as well as the acceleration of reactions by electro-sorbates (electrocatalysis). We deal mostly with both normal and resonance Raman effects on fairly thick surface films in contrast to surface-enhanced Raman investigations of monolayer adsorbates, which is covered in another lecture. Laser Raman spectroelectrochemical studies of corrosion and film formation on such metals as Pb, Ag, Fe, Ni, Co, Cr, Au, stainless steel, etc. in various solution conditions are discussed. Further extension of the technique to studies in high-temperature and high-pressure aqueous environments is demonstrated. Results of studies of the structure of corrosion inhibitors are also presented. As applications of the LRS technique in the area of electrocatalysis, we cite studies of the structure of transition metal macrocyclic compounds, i.e., phthalocyanines and porphyrins, used for catalysis of the oxygen reduction reaction. 104 refs., 20 figs.

Melendres, C.A.

1988-01-01

38

Passivity and electrocatalysis of nanostructured nickel encapsulated in carbon.  

PubMed

Metallic nickel is a powerful electrocatalyst in alkaline solution and is able to be used in the alkaline fuel cell. However, in acidic solution, electrocatalysis is impossible because the metal is subject to rapid corrosion at low pH for all potentials at which an acidic fuel cell would operate. Here we report the synthesis and passive nature of a nickel-carbon nanostructured material which shows electrocatalytic activity. A thin film composed of nickel and carbon prepared by co-sputtering a graphite target partially covered with a nickel foil shows remarkable passivity against corrosion when polarized in hot sulphuric acid. The film, which contains 21 atom-% nickel, also shows significant electrocatalysis of the hydrogen oxidation reaction, and therefore forms the basis of a new type of fuel cell anode catalyst. High-resolution transmission electron microscopy (HRTEM) reveals a nanostructure of carbon-encapsulated nickel nanocrystals of ?ca. 4 nm diameter. The passive nature of the material against corrosion is due to protection generated by the presence of a very thin carbon-rich layer encapsulating the nanoparticulate catalyst: this is a new form of passivation. PMID:21695331

Haslam, Gareth E; Chin, Xiao-Yao; Burstein, G Tim

2011-07-28

39

A multiscale study of atomic interactions in the electrochemical double layer applied to electrocatalysis  

E-print Network

This work is an integrated study of chemical and electrostatic interactions in the electrochemical double layer, and their significance for accurate prediction of reaction kinetics in electrocatalysis. First, a kinetic ...

Bonnet, Nicéphore

2011-01-01

40

Platinum nanocatalysts loaded on graphene oxide-dispersed carbon nanotubes with greatly enhanced peroxidase-like catalysis and electrocatalysis activities  

NASA Astrophysics Data System (ADS)

A powerful enzymatic mimetic has been fabricated by employing graphene oxide (GO) nanocolloids to disperse conductive carbon supports of hydrophobic carbon nanotubes (CNTs) before and after the loading of Pt nanocatalysts. The resulting GOCNT-Pt nanocomposites could present improved aqueous dispersion stability and Pt spatial distribution. Unexpectedly, they could show greatly enhanced peroxidase-like catalysis and electrocatalysis activities in water, as evidenced in the colorimetric and electrochemical investigations in comparison to some inorganic nanocatalysts commonly used. Moreover, it is found that the new enzyme mimetics could exhibit peroxidase-like catalysis activity comparable to natural enzymes; yet, they might circumvent some of their inherent problems in terms of catalysis efficiency, electron transfer, environmental stability, and cost effectiveness. Also, sandwiched electrochemical immunoassays have been successfully conducted using GOCNT-Pt as enzymatic tags. Such a fabrication avenue of noble metal nanocatalysts loaded on well-dispersed conductive carbon supports should be tailored for the design of different enzyme mimics promising the extensive catalysis applications in environmental, medical, industrial, and particularly aqueous biosensing fields.A powerful enzymatic mimetic has been fabricated by employing graphene oxide (GO) nanocolloids to disperse conductive carbon supports of hydrophobic carbon nanotubes (CNTs) before and after the loading of Pt nanocatalysts. The resulting GOCNT-Pt nanocomposites could present improved aqueous dispersion stability and Pt spatial distribution. Unexpectedly, they could show greatly enhanced peroxidase-like catalysis and electrocatalysis activities in water, as evidenced in the colorimetric and electrochemical investigations in comparison to some inorganic nanocatalysts commonly used. Moreover, it is found that the new enzyme mimetics could exhibit peroxidase-like catalysis activity comparable to natural enzymes; yet, they might circumvent some of their inherent problems in terms of catalysis efficiency, electron transfer, environmental stability, and cost effectiveness. Also, sandwiched electrochemical immunoassays have been successfully conducted using GOCNT-Pt as enzymatic tags. Such a fabrication avenue of noble metal nanocatalysts loaded on well-dispersed conductive carbon supports should be tailored for the design of different enzyme mimics promising the extensive catalysis applications in environmental, medical, industrial, and particularly aqueous biosensing fields. Electronic supplementary information (ESI) available: The catalysis mechanism, catalytic dynamic parameters, the interferent effects on H2O2 detections, investigations of time-dependent dispersion stabilities, double-reciprocal plots of catalysis activities, and electrocatalysis comparison between GOCNT-Pt nanocomposites and HRP. See DOI: 10.1039/c4nr00983e

Wang, Hua; Li, Shuai; Si, Yanmei; Zhang, Ning; Sun, Zongzhao; Wu, Hong; Lin, Yuehe

2014-06-01

41

Efficient UV photocatalysis assisted by densely distributed aluminum nanoparticles  

NASA Astrophysics Data System (ADS)

Aluminum nanoparticles fabricated by oblique angle deposition (OAD) successfully increased the yield and reaction rate of UV photocatalysis due to the localized surface plasmon resonance (LSPR) effect. Nanoparticles 20–60?nm in size were formed in an area larger than ~1?cm2 when the film was highly tilted during the thermal deposition process. The size and density of these nanoparticles were readily controlled by the deposition thickness and speed. The yield of photocatalytic reactions increased by a factor of ~2, while the reaction rate increased by up to ~10 times. The aluminum nanostructures presented here are of tremendous advantage for future applications in photocatalysis through efficient coupling with UV light.

Honda, M.; Kumamoto, Y.; Taguchi, A.; Saito, Y.; Kawata, S.

2015-05-01

42

Photocatalytic water treatment: solar energy applications  

Microsoft Academic Search

During the past 20 years research and development in the area of photocatalysis have been tremendous. One of the major applications of this technology is the degradation of organic pollutants in water and air streams which is considered as one of the so-called advanced oxidation processes. This overview briefly describes the basic principles of photocatalysis, focusing in particular on important

Detlef Bahnemann

2004-01-01

43

Protein Electrocatalysis for Direct Sensing of Circulating MicroRNAs.  

PubMed

MicroRNAs (miRNAs) are potentially useful biomarkers for diagnosis, classification, and prognosis of many diseases, including cancer. Herein, we developed a protein-facilitated electrocatalytic quadroprobe sensor (Sens(PEQ)) for detection of miRNA signature of chronic lymphocytic leukemia (CLL) in human serum. The developed signal-ON sensor provides a compatible combination of two DNA adaptor strands modified with four methylene blue molecules and electrocatalysis using glucose oxidase in order to enhance the overall signal gain. This enhanced sensitivity provided the response necessary to detect the low-abundant serum miRNAs without preamplification. The developed Sens(PEQ) is exquisitely sensitive to subtle ?-stack perturbations and capable of distinguishing single base mismatches in the target miRNA. Furthermore, the developed sensor was employed for profiling of three endogenous miRNAs characteristic to CLL, including hsa-miR-16-5p, hsa-miR-21-5p, and hsa-miR-150-5p in normal healthy serum, chronic lymphocytic leukemia Rai stage 1 (CLL-1), and stage 3 (CLL-3) sera, using a non-human cel-miR-39-3p as an internal standard. The sensor results were verified by conventional SYBR green-based quantitative reverse-transcription polymerase chain reaction (RT-qPCR) analysis. PMID:25495265

Labib, Mahmoud; Khan, Nasrin; Berezovski, Maxim V

2015-01-20

44

Dendritic assembly of gold nanoparticles during fuel-forming electrocatalysis.  

PubMed

We observe the dendritic assembly of alkanethiol-capped gold nanoparticles on a glassy carbon support during electrochemical reduction of protons and CO2. We find that the primary mechanism by which surfactant-ligated gold nanoparticles lose surface area is by taking a random walk along the support, colliding with their neighbors, and fusing to form dendrites, a type of fractal aggregate. A random walk model reproduces the fractal dimensionality of the dendrites observed experimentally. The rate at which the dendrites form is strongly dependent on the solubility of the surfactant in the electrochemical double layer under the conditions of electrolysis. Since alkanethiolate surfactants reductively desorb at potentials close to the onset of CO2 reduction, they do not poison the catalytic activity of the gold nanoparticles. Although catalyst mobility is typically thought to be limited for room-temperature electrochemistry, our results demonstrate that nanoparticle mobility is significant under conditions at which they electrochemically catalyze gas evolution, even in the presence of a high surface area carbon and binder. A careful understanding of the electrolyte- and polarization-dependent nanoparticle aggregation kinetics informs strategies for maintaining catalyst dispersion during fuel-forming electrocatalysis. PMID:24766431

Manthiram, Karthish; Surendranath, Yogesh; Alivisatos, A Paul

2014-05-21

45

Supporting Information to: Single-Molecule Electrocatalysis by Single-Walled Carbon Nanotubes  

E-print Network

S1 Supporting Information to: Single-Molecule Electrocatalysis by Single-Walled Carbon Nanotubes. Experimental Methods I.1. Purification of SWNTs. The single-walled carbon nanotubes were purchased from Carbon Nanotechnologies Incorporated (Purified HiPCO single-walled carbon nanotubes). These SWNTs have an average diameter

Chen, Peng

46

Graphene thickness-controlled photocatalysis and surface enhanced Raman scattering  

NASA Astrophysics Data System (ADS)

Exceptional photocatalytic enhancement of graphene-semiconductor composites has been widely reported, but our understanding of the role that graphene plays in this enhancement remains limited, which arises from the difficulty of precisely controlling graphene hybridization. Here we present a general platform of a graphene-semiconductor hybrid panel (GHP) system wherein a precise number of layers of graphene are hybridized with photoactive semiconductors (e.g. TiO2, ZnO) to study systematically how graphene affects the photocatalysis. The results show that the graphene enhancement of the photocatalysis depends on the number of graphene layers, with the maximum performance observed at 3 layers. Photodeposited indicators of gold particles further reveal that graphene thickness governs the density of photocatalytic sites and charge transfer efficiency at the graphene-semiconductor interfaces. We suggest that quantized energy levels caused by different numbers of stacked graphene sheets along the vector normal to the graphene basal plane affect the charge transfer routes and lead to the graphene thickness-controlled photocatalysis. GHP substrates deposited with gold particles are promising, uniform substrates for surface enhanced Raman scattering (SERS) applications with the enhancement factor as high as ~108 on 3-layer graphene.Exceptional photocatalytic enhancement of graphene-semiconductor composites has been widely reported, but our understanding of the role that graphene plays in this enhancement remains limited, which arises from the difficulty of precisely controlling graphene hybridization. Here we present a general platform of a graphene-semiconductor hybrid panel (GHP) system wherein a precise number of layers of graphene are hybridized with photoactive semiconductors (e.g. TiO2, ZnO) to study systematically how graphene affects the photocatalysis. The results show that the graphene enhancement of the photocatalysis depends on the number of graphene layers, with the maximum performance observed at 3 layers. Photodeposited indicators of gold particles further reveal that graphene thickness governs the density of photocatalytic sites and charge transfer efficiency at the graphene-semiconductor interfaces. We suggest that quantized energy levels caused by different numbers of stacked graphene sheets along the vector normal to the graphene basal plane affect the charge transfer routes and lead to the graphene thickness-controlled photocatalysis. GHP substrates deposited with gold particles are promising, uniform substrates for surface enhanced Raman scattering (SERS) applications with the enhancement factor as high as ~108 on 3-layer graphene. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr03877k

Kuo, Cheng-Chi; Chen, Chun-Hu

2014-10-01

47

Electrocatalysis of anodic and cathodic oxygen-transfer reactions  

SciTech Connect

The electrocatalysis of oxygen-transfer reactions is discussed in two parts. In Part I, the reduction of iodate (IO{sub 3}{sup {minus}}) is examined as an example of cathodic oxygen transfer. On oxide-covered Pt electrodes (PtO), a large cathodic current is observed in the presence of IO{sub 3}{sup {minus}} to coincide with the reduction of PtO. The total cathodic charge exceeds the amount required for reduction of PtO and IO{sub 3}{sup {minus}} to produce an adsorbed product. An electrocatalytic link between reduction of IO{sub 3}{sup {minus}} and reduction of PtO is indicated. In addition, on oxide-free Pt electrodes, the reduction of IO{sub 3}{sup {minus}} is determined to be sensitive to surface treatment. The electrocatalytic oxidation of CN{sup {minus}} is presented as an example of anodic oxygen transfer in Part II. The voltametric response of CN{sup {minus}} is virtually nonexistent at PbO{sub 2} electrodes. The response is significantly improved by doping PbO{sub 2} with Cu. Cyanide is also oxidized effectively at CuO-film electrodes. Copper is concluded to serve as an adsorption site for CN{sup {minus}}. It is proposed that an oxygen tunneling mechanism comparable to electron tunneling does not occur at the electrode-solution interface. The adsorption of CN{sup {minus}} is therefore considered to be a necessary prerequisite for oxygen transfer. 201 refs., 23 figs., 2 tabs.

Wels, B.R.

1990-09-21

48

Protein structure-sensitive electrocatalysis at dithiothreitol-modified electrodes.  

PubMed

Dithiothreitol (DTT)-mercury and DTT-solid amalgam electrodes are proposed for protein microanalysis by means of constant current chronopotentiometric stripping (CPS). At the DTT-modified hanging mercury drop electrode (DTT-HMDE), proteins at nanomolar concentrations produce the CPS peak H, which is due to the protein catalyzed hydrogen evolution. Self-assembled monolayers (SAMs) of DTT at the electrode surface protected surface-attached proteins from the electric field-driven denaturation, but did not interfere with the electrocatalysis. Using CPS peak H, native and denatured forms of bovine serum albumin (BSA) and of other proteins were easily distinguished. On the other hand, in usual slow scan voltammetry (scan rates between 50 mV/s and 1 V/s), the adsorbed BSA behaved as fully or partially denatured. BSA-modified DTT-HMDE was exposed to different potentials, E(B) for 60 s, followed by CPS measurement. Three E(B) regions were observed, in which either BSA remained native (A, -0.1 to -0.3 V), was denatured (B, -0.35 to -1.4 V), or underwent desorption (C, at potentials more negative than -1.4 V). At potentials more positive than the reduction potential of the DTT Hg-S bond (approximately -0.65 V against Ag|AgCl|3 M KCl), the densely packed DTT SAM was impermeable to [Ru(NH(3))(6)](3+). At more negative potentials, the DTT SAM was disturbed, but under conditions of CPS (with very fast potential changes), this SAM still protected the protein from surface-induced denaturation. Thiol-modified Hg electrodes in combination with CPS represent a new tool for protein analysis in biomedicine and proteomics. PMID:20557043

Ostatná, Veronika; Cernocká, Hana; Palecek, Emil

2010-07-14

49

Decomposition of NO in automobile exhaust by plasma-photocatalysis synergy.  

PubMed

The combination of plasma discharge and TiO2 photocatalysis exhibits high performances in the removal of nitrogen monoxide (NO). This article is aimed at elucidating the relationships between NO decomposition efficiency and various experimental parameters, including voltages, humidity and temperature. The experimental results indicate that the efficiency of NO removal by synergic plasma-catalyst coupling is significantly higher than plasma only or photocatalyst only systems. Moreover, the NO removal efficiency improves with the increase of applied voltage. Meanwhile, a higher humidity results in a reduced number of electron-hole pairs at the surface of TiO2 photocatalyst, leading to lower synergic purification efficiencies. Finally, the efficiency of NO removal is raised with the increase of temperature due to the fact that the adsorption of NO and water by nano-TiO2 is affected by environmental temperature. PMID:23892616

Chen, Meng; Jin, Lisheng; Liu, Yanhua; Guo, Xiurong; Chu, Jiangwei

2014-01-01

50

SOME RECENT STUDIES IN RUGHENIUM ELECTROCHEMISTRY AND ELECTROCATALYSIS.  

SciTech Connect

Ruthenium is a metal of a considerable importance in electrochemical science and technology. It is a catalyst or co-catalyst material in Pt-Ru alloys for methanol- and reformate hydrogen-oxidation in fuel cells, while ruthenium oxide, a component in chlorine-evolution catalysts, represents an attractive material for electrochemical supercapacitors. Its facile surface oxidation generates an oxygen-containing species that provides active oxygen in some reactions. Ru sites in Pt-Ru catalysts increase the ''CO tolerance'' of Pt in the catalytic oxidation-reaction in direct methanol fuel cells (DMFC) and in reformate hydrogen-oxidation in proton exchange membrane fuel cells (PEMFC). The mechanism of Ru action is not completely understood, although current consensus revolves around the so-called ''bifunctional mechanism'' wherein Ru provides oxygenated species to oxidize CO that blocks Pt sites, and has an electronic effect on Pt-CO interaction. While various studies of polycrystalline Ru go back several decades those involving single crystal surfaces and the structural sensitivity of reactions on Ru surfaces emerged only recently. Using well-ordered single crystalline surfaces brings useful information as the processes on realistic catalysts are far too complex to allow identification of the microscopic reaction steps. In this article, we focus on progress in model systems and conditions, such as electrochemistry and electrocatalysis on bare and Pt-modified well-ordered Ru(0001) and Ru(10{bar 1}0) single-crystal surfaces. We also review current understanding of the mechanistic principles of Pt-Ru systems and a new development of a Pt submonolayer on Ru support electrocatalyst. Ruthenium crystallizes in a hexagonal close-packed structure, (hcp). Figure 1.1 shows the two single crystal surfaces of Ru. The Ru(0001) surface possesses the densest, i.e. hexagonal arrangement of atoms, Fig. 1.1a. The other plane, Ru(10{bar 1}0), can have one of the two terminations of the surface atoms, Fig. 1.1b. One termination can be described as a stepped surface with a trigonal arrangement of atoms in two-atom-long terraces with a step of the same orientation; the other termination is a square-symmetrical arrangement of atoms in two-atom-long terraces with the same orientation of atoms in steps. In the faced-centered cubic (fcc) system, these three structures are uniquely defined and labeled as (111), (110), and (210), respectively.

MARINKOVIC, N.S.; VUKMIROVIC, M.B.; ADZIC, R.R.

2006-08-01

51

New Electrochemical Methods for Studying Nanoparticle Electrocatalysis and Neuronal Exocytosis  

NASA Astrophysics Data System (ADS)

This dissertation presents the construction and application of micro and nanoscale electrodes for electroanalytical analysis. The studies presented herein encompass two main areas: electrochemical catalysis, and studies of the dynamics of single cell exocytosis. The first portion of this dissertation engages the use of Pt nanoelectrodes to study the stability and electrocatalytic properties of materials. A single nanoparticle electrode (SNPE) was fabricated by immobilizing a single Au nanoparticle on a Pt disk nanoelectrode via an amine-terminated silane cross linker. In this manner we were able to effectively study the electrochemistry and electrocatalytic activity of single Au nanoparticles and found that the electrocatalytic activity is dependent on nanoparticle size. This study can further the understanding of the structure-function relationship in nanoparticle based electrocatalysis. Further work was conducted to probe the stability of Pt nanoelectrodes under conditions of potential cycling. Pt based catalysts are known to deteriorate under such conditions due to losses in electrochemical surface area and Pt dissolution. By using Pt disk nanoelectrodes we were able to study Pt dissolution via steady-state voltammetry. We observed an enhanced dissolution rate and higher charge density on nanoelectrodes than that previously found on macro scale electrodes. The goal of the second portion of this dissertation is to develop new analytical methods to study the dynamics of exocytosis from single cells. The secretion of neurotransmitters plays a key role in neuronal communication, and our studies highlight how bipolar electrochemistry can be employed to enhance detection of neurotransmitters from single cells. First, we developed a theory to quantitatively characterize the voltammetric behavior of bipolar carbon fiber microelectrodes and secondly applied those principles to single cell detection. We showed that by simply adding an additional redox mediator to the back-fill solution of a carbon fiber microelectrode, there is a significant enhancement in detection. Additionally we used solid state nanopores to detect individual phospholipid vesicles in solution. Vesicles are key cellular components that play essential biological roles especially in neurotransmission. This work represents preliminary studies in detection and size determination from vesicles isolated from individual cells.

Cox, Jonathan T.

52

Roles of cocatalysts in photocatalysis and photoelectrocatalysis.  

PubMed

Since the 1970s, splitting water using solar energy has been a focus of great attention as a possible means for converting solar energy to chemical energy in the form of clean and renewable hydrogen fuel. Approaches to solar water splitting include photocatalytic water splitting with homogeneous or heterogeneous photocatalysts, photoelectrochemical or photoelectrocatalytic (PEC) water splitting with a PEC cell, and electrolysis of water with photovoltaic cells coupled to electrocatalysts. Though many materials are capable of photocatalytically producing hydrogen and/or oxygen, the overall energy conversion efficiency is still low and far from practical application. This is mainly due to the fact that the three crucial steps for the water splitting reaction: solar light harvesting, charge separation and transportation, and the catalytic reduction and oxidation reactions, are not efficient enough or simultaneously. Water splitting is a thermodynamically uphill reaction, requiring transfer of multiple electrons, making it one of the most challenging reactions in chemistry. This Account describes the important roles of cocatalysts in photocatalytic and PEC water splitting reactions. For semiconductor-based photocatalytic and PEC systems, we show that loading proper cocatalysts, especially dual cocatalysts for reduction and oxidation, on semiconductors (as light harvesters) can significantly enhance the activities of photocatalytic and PEC water splitting reactions. Loading oxidation and/or reduction cocatalysts on semiconductors can facilitate oxidation and reduction reactions by providing the active sites/reaction sites while suppressing the charge recombination and reverse reactions. In a PEC water splitting system, the water oxidation and reduction reactions occur at opposite electrodes, so cocatalysts loaded on the electrode materials mainly act as active sites/reaction sites spatially separated as natural photosynthesis does. In both cases, the nature of the loaded cocatalysts and their interaction with the semiconductor through the interface/junction are important. The cocatalyst can provide trapping sites for the photogenerated charges and promote the charge separation, thus enhancing the quantum efficiency; the cocatalysts could improve the photostability of the catalysts by timely consuming of the photogenerated charges, particularly the holes; most importantly, the cocatalysts catalyze the reactions by lowering the activation energy. Our research shows that loading suitable dual cocatalysts on semiconductors can significantly increase the photocatalytic activities of hydrogen and oxygen evolution reactions, and even make the overall water splitting reaction possible. All of these findings suggest that dual cocatalysts are necessary for developing highly efficient photocatalysts for water splitting reactions. PMID:23530781

Yang, Jinhui; Wang, Donge; Han, Hongxian; Li, Can

2013-08-20

53

Non-thermal Plasma - Nanometer TiO2 Photocatalysis for Formaldehyde Decomposition  

E-print Network

In non-thermal plasma-nanometer TiO2 photocatalysis, the techniques of photocatalysis and plasma are combined, and do not need ultraviolet light. It can make use of some kinds of energy in the process of decomposing, while at the same time producing...

Yuan, Q.; Feng, G.; Guang, X.

2006-01-01

54

Friedel-Crafts Amidoalkylation via Thermolysis and Oxidative Photocatalysis  

PubMed Central

Friedel-Crafts amidoalkylation was achieved by oxidation of dialkylamides using persulfate (S2O82?) in the presence of the visible light catalyst, Ru(bpy)3Cl2, at room temperature, via a reactive N-acyliminium intermediate. Alternatively, mild heating of the dialkylamides and persulfate afforded a metal and Lewis acid-free Friedel-Crafts amidoalkylation. Alcohols and electron–rich arenes served as effective nucleophiles, forming new C–O or C–C bonds. In general, photocatalysis provided higher yields and better selectivities. PMID:22458307

Dai, Chunhui; Meschini, Francesco; Narayanam, Jagan M. R.; Stephenson, Corey R. J.

2012-01-01

55

Friedel-Crafts amidoalkylation via thermolysis and oxidative photocatalysis.  

PubMed

Friedel-Crafts amidoalkylation was achieved by oxidation of dialkylamides using persulfate (S(2)O(8)(2-)) in the presence of the visible light catalyst, Ru(bpy)(3)Cl(2), at room temperature, via a reactive N-acyliminium intermediate. Alternatively, mild heating of the dialkylamides and persulfate afforded a metal and Lewis acid-free Friedel-Crafts amidoalkylation. Alcohols and electron-rich arenes served as effective nucleophiles, forming new C-O or C-C bonds. In general, photocatalysis provided higher yields and better selectivities. PMID:22458307

Dai, Chunhui; Meschini, Francesco; Narayanam, Jagan M R; Stephenson, Corey R J

2012-05-01

56

TiO{sub 2}-coated carbon nanotubes: A redshift enhanced photocatalysis at visible light  

SciTech Connect

Annealing of carbon nanotubes coated with thin and uniform TiO{sub 2} results in carbon diffusion into oxygen lattices and doping induced redshift is evident by an efficient photocatalysis at visible light. The underlying mechanism is discussed.

Lu, S.-Y.; Tang, C.-W.; Lin, Y.-H.; Kuo, H.-F.; Lai, Y.-C.; Ouyang Hao; Hsu, W.-K. [Department of Materials Science and Engineering, National Tsing-Hua University, HsinChu 30013, Taiwan (China); Tsai, M.-Y. [Instrument Technology Research Center, National Applied Research Laboratories, HsinChu 30076, Taiwan (China)

2010-06-07

57

Experiment on TiO2/AC Photocatalysis Technique to Eliminate Toluene in Air Conditioning Systems  

E-print Network

at present, the article proposes that new-type purification technique and hopes to promote the upgrading of the product about purification. 2. INTRODUTION ON THE STRURE AND STUFF OF ACTIVE CARBON AND NANO- TITANIUM DIOXIDE PHOTOCATALYSIS PURIFICATION... WEB What is called active carbon and nano-titanium dioxide photocatalysis technique is to utilize the method of compounding active carbon and nanometer photocatalyst to firstly form absorption layer on supporting body surface by gluing, which...

Hu, Y.; Feng, G.; Yuan, Q.

2006-01-01

58

Visible Light Photocatalysis: The Development of Photocatalytic Radical Ion Cycloadditions  

PubMed Central

Photochemistry has the potential to significantly impact multiple aspects of chemical synthesis, in part because photoinduced reactions can be used to construct molecular architectures that would otherwise be difficult to produce. Nevertheless, organic chemists have been slow to embrace photochemical synthesis because of technical complications associated with the use of ultraviolet light. Our laboratory has been part of an effort to design synthetically useful reactions that utilize visible light. This strategy enables the synthesis of a diverse range of organic structures by generation of a variety of reactive intermediates under exceptionally mild conditions. This Perspective article describes the reasoning that led to the conception of our first experiments in this area, the features of our reaction design that have been most powerful in the discovery of new processes, and a few of the possible future areas in which visible light photocatalysis might have a large impact. PMID:23691491

Yoon, Tehshik P.

2013-01-01

59

Direct Electrochemistry and Electrocatalysis of Myoglobin Immobilized on Graphene-CTAB-Ionic Liquid Nanocomposite Film  

SciTech Connect

We have investigated direct electrochemistry and electrocatalysis of myoglobin immobilized on graphene-cetylramethylammonium bromide (CTAB)-ionic liquid nanocomposite film on a glassy carbon electrode. The nanocomposite was characterized by TEM, SEM, XPS, and electrochemistry. It was found that the high surface area of graphene was helpful for immobilizing more proteins and the nanocomposite film can provide a favorable microenvironment for MB to retain its native structure and activity and to achieve reversible direct electron transfer reaction at an electrode. The nanocomposite films also exhibit good stability and catalytic activities for the electrocatalytic reduction of H2O2.

Liao, Honggang; Wu, Hong; Wang, Jun; Liu, Jun; Jiang, Yanxia; Sun, Shigang; Lin, Yuehe

2010-10-01

60

NASA's Potential Contributions for Using Solar Ultraviolet Radiation in Conjunction with Photocatalysis for Urban Air Pollution Mitigation  

NASA Technical Reports Server (NTRS)

More than 75 percent of the U.S. population lives in urban communities where people are exposed to levels of smog or pollution that exceed the EPA (U.S. Environmental Protection Agency) safety standards. Urban air quality presents a unique problem because of a number of complex variables, including traffic congestion, energy production, and energy consumption activities, all of which can contribute to and affect air pollution and air quality in this environment. In environmental engineering, photocatalysis is an area of research whose potential for environmental clean-up is rapidly developing popularity and success. Photocatalysis, a natural chemical process, is the acceleration of a photoreaction in the presence of a catalyst. Photocatalytic agents are activated when exposed to near UV (ultraviolet) light (320-400 nm) and water. In recent years, surfaces coated with photocatalytic materials have been extensively studied because pollutants on these surfaces will degrade when the surfaces are exposed to near UV light. Building materials, such as tiles, cement, glass, and aluminum sidings, can be coated with a thin film of a photocatalyst. These coated materials can then break down organic molecules, like air pollutants and smog precursors, into environmentally friendly compounds. These surfaces also exhibit a high affinity for water when exposed to UV light. Therefore, not only are the pollutants decomposed, but this superhydrophilic nature makes the surface self-cleaning, which helps to further increase the degradation rate by allowing rain and/or water to wash byproducts away. According to the Clean Air Act, each individual state is responsible for implementing prevention and regulatory programs to control air pollution. To operate an air quality program, states must adopt and/or develop a plan and obtain approval from the EPA. Federal approval provides a means for the EPA to maintain consistency among different state programs and ensures that they comply with the requirements of the Clean Air Act.

Ryan, robert E.; Underwood, Lauren W.

2007-01-01

61

Photocatalysis deconstructed: design of a new selective catalyst for artificial photosynthesis.  

PubMed

A rapid increase in anthropogenic emission of greenhouse gases, mainly carbon dioxide, has been a growing cause for concern. While photocatalytic reduction of carbon dioxide (CO2) into solar fuels can provide a solution, lack of insight into energetic pathways governing photocatalysis has impeded study. Here, we utilize measurements of electronic density of states (DOS), using scanning tunneling microscopy/spectroscopy (STM/STS), to identify energy levels responsible for photocatalytic reduction of CO2-water in an artificial photosynthetic process. We introduce desired states in titanium dioxide (TiO2) nanoparticles, using metal dopants or semiconductor nanocrystals, and the designed catalysts were used for selective reduction of CO2 into hydrocarbons, alcohols, and aldehydes. Using a simple model, we provide insights into the photophysics governing this multielectron reduction and design a new composite photocatalyst based on overlapping energy states of TiO2 and copper indium sulfide (CIS) nanocrystals. These nanoparticles demonstrate the highest selectivity for ethane (>70%) and a higher efficiency of converting ultraviolet radiation into fuels (4.3%) using concentrated sunlight (>4 Sun illumination), compared with platinum-doped TiO2 nanoparticles (2.1%), and utilize hot electrons to tune the solar fuel from alkanes to aldehydes. These results can have important implications for the development of new inexpensive photocatalysts with tuned activity and selectivity. PMID:24443959

Singh, Vivek; Beltran, Ignacio J Castellanos; Ribot, Josep Casamada; Nagpal, Prashant

2014-02-12

62

Carbon Dioxide reduction by non-equilibrium electrocatalysis plasma reactor  

NASA Astrophysics Data System (ADS)

A possible strategy to increase the added value from CCS, is to consider it as a raw material for the production of liquid fuels, or chemical products. The most studied ways related to CO2 reduction, with formation of molecules such as CH3OH or syngas, is the reaction with H2 (exothermic reaction needing catalytic activation), or CH4 (endothermic reaction taking place at high temperature) with the use of a catalyst. The synthesis of CH3OH is performed on Lewis acid type sites (default of electrons) Cu/Zn/Al2O3. However the products of the reaction i.e. the water and methanol molecules, are very polar, resulting in a very low desorption rate. So in this reaction the key step is water desorption (Lewis basis). The increase of temperature in order to increase this desorption rate, leads to a cracking and the deposition of carbon in the catalyst, limiting its lifetime. Plasma driven catalysis allows firstly, a vibrational activation of CO2, H2 or CH4 through electron-molecule collisions, making easier their dissociation at low temperature and secondly expels water from the catalyst sites by supplying electrons (electropolarisation). The results show an increase of the yield in CH3OH with plasma and catalyst, confirming the action of the plasma. However energy consumption remains relatively high.

Amouroux, J.; Cavadias, S.; Doubla, A.

2011-03-01

63

Molecular selective photocatalysis by TiO2/nanoporous silica core/shell particulates.  

PubMed

The coating of TiO(2) particles (P25) by a nanoporous silica layer was conducted to impart molecular recognitive photocatalytic ability. TiO(2)/nanoporous silica core/shell particles with varied pore diameters of the shell were synthesized by the reaction of P25 with an aqueous mixture of tetraethoxysilane and alkyltrimethylammonium chloride with varied alkyl chain lengths, followed by calcination. The TEM and nitrogen adsorption/desorption isotherms of the products showed that a nanoporous silica shell with a thickness of ca. 2nm and controlled pore diameter (1.2, 1.6, and 2.7 nm) was deposited on the titania particle when surfactants with different alkyl chain lengths (C12, C16 and C22) were used. The water vapor adsorption/desorption isotherms of the core/shell particles revealed that a larger amount of water adsorbed on the core/shell particles when the pore diameter is larger. The (29)Si MAS NMR spectra of the core/shell particles showed that the amount of surface silanol groups was independent of the water vapor adsorption capacity of the products. The possible molecular recognitive photocatalysis on the products was investigated under UV irradiation using two kinds of aqueous mixtures containing different organic compounds with varied sizes and functional groups: a 4-butylphenol, 4-hexylphenol, and 4-nonylphenol mixture and a 2-nitrophenol, 2-nitro-4-phenylphenol, and 4-nitro-2,6-diphenylphenol mixture. It was found that the core/shell particles exhibited selective adsorption-driven molecular recognitive photocatalytic decomposition of 4-nonylphenol and 2-nitrophenol in the two mixtures. PMID:21419418

Ide, Yusuke; Koike, Yusuke; Ogawa, Makoto

2011-06-01

64

Ionic liquid-functionalized fluorescent carbon nanodots and their applications in electrocatalysis, biosensing, and cell imaging.  

PubMed

In this article, ionic liquid-functionalized carbon nanodots (IL-CDs) were produced in a simple manner by electrochemical exfoliation of graphite rods in the presence of an amino-terminated ionic liquid, and their preliminary applications were exploited. TEM and AFM results showed that these IL-CDs are about 2.6 nm in diameter. The small-sized IL-CDs have strong photoluminescence, with a quantum yield of about 11.3%, and could be used for cell imaging. Moreover, the IL-CDs exhibit good electron transfer properties and catalytic activities for O2 and H2O2 reduction. Additionally, the as-prepared IL-CDs can be applied as a matrix for immobilizing enzymes (glucose oxidase) to construct biosensors. Due to these favorable properties, IL-CDs will find promising practical applications in electrocatalysis, biosensing, and bioimaging. PMID:25418328

Li, Haijuan; Chen, Limei; Wu, Haoxi; He, Haili; Jin, Yongdong

2014-12-16

65

Strongly coupled inorganic/nanocarbon hybrid materials for advanced electrocatalysis.  

PubMed

Electrochemical systems, such as fuel cell and water splitting devices, represent some of the most efficient and environmentally friendly technologies for energy conversion and storage. Electrocatalysts play key roles in the chemical processes but often limit the performance of the entire systems due to insufficient activity, lifetime, or high cost. It has been a long-standing challenge to develop efficient and durable electrocatalysts at low cost. In this Perspective, we present our recent efforts in developing strongly coupled inorganic/nanocarbon hybrid materials to improve the electrocatalytic activities and stability of inorganic metal oxides, hydroxides, sulfides, and metal-nitrogen complexes. The hybrid materials are synthesized by direct nucleation, growth, and anchoring of inorganic nanomaterials on the functional groups of oxidized nanocarbon substrates including graphene and carbon nanotubes. This approach affords strong chemical attachment and electrical coupling between the electrocatalytic nanoparticles and nanocarbon, leading to nonprecious metal-based electrocatalysts with improved activity and durability for the oxygen reduction reaction for fuel cells and chlor-alkali catalysis, oxygen evolution reaction, and hydrogen evolution reaction. X-ray absorption near-edge structure and scanning transmission electron microscopy are employed to characterize the hybrids materials and reveal the coupling effects between inorganic nanomaterials and nanocarbon substrates. Z-contrast imaging and electron energy loss spectroscopy at single atom level are performed to investigate the nature of catalytic sites on ultrathin graphene sheets. Nanocarbon-based hybrid materials may present new opportunities for the development of electrocatalysts meeting the requirements of activity, durability, and cost for large-scale electrochemical applications. PMID:23339685

Liang, Yongye; Li, Yanguang; Wang, Hailiang; Dai, Hongjie

2013-02-13

66

CO2 SEQUESTRATION AND RECYCLE BY PHOTOCATALYSIS WITH VISIBLE LIGHT  

SciTech Connect

Visible light-photocatalysis could provide a cost-effective route to recycle CO{sub 2} to useful chemicals or fuels. Development of an effective catalyst for the photocatalytic synthesis requires (i) the knowledge of the surface band gap and its relation to the surface structure, (ii) the reactivity of adsorbates and their reaction pathways, and (iii) the ability to manipulate the actives site for adsorption, surface reaction, and electron transfer. The objective of this research is to study the photo-catalytic activity of TiO{sub 2}-base catalyst. A series of TiO{sub 2}-supported metal catalysts were prepared for determining the activity and selectivity for the synthesis of methane and methanol. 0.5 wt% Cu/SrTiO{sub 3} was found to be the most active and selective catalyst for methanol synthesis. The activity of the catalyst decreased in the order: Ti silsesquioxane > Cu/SrTiO{sub 3} > Pt/TiO{sub 2} > Cu/TiO{sub 2} > TiO{sub 2} > Rh/TiO{sub 2}. To further increase the number of site for the reaction, we propose to prepare monolayer and multiplayer TiOx on high surface area mesoporous oxides. These catalysts will be used for in situ IR study in the Phase II research project to determine the reactivity of adsorbates. Identification of active adsorbates and sites will allow incorporation of acid/basic sites to alter the nature of CO{sub 2} and H{sub 2}O adsorbates and with Pt/Cu sites to direct reaction pathways of surface intermediates, enhancing the overall activity and selectivity for methanol and hydrocarbon synthesis. The overall goal of this research is to provide a greater predictive capability for the design of visible light-photosynthesis catalysts by a deeper understanding of the reaction kinetics and mechanism as well as by better control of the coordination/chemical environment of active sites.

Steven S.C. Chuang

2001-10-01

67

Removal of Indoor Air ppb Level Volatile Organic Compounds (VOCs) and NOx by Heterogeneous Photocatalysis  

Microsoft Academic Search

VOCs and NOx are the major pollutants in Hong Kong indoor environment. Traditional air purification method such as adsorption by activated carbon is not reliable and get saturated easily. Adsorption merely transfers pollutants from gaseous phase to solid phase and poses the disposal problem. Using photocatalysis, however, strong oxidant such as hydroxyl radical is generated and actually oxidized the pollutant

Chio Hang Ao; Shun Cheng Lee

2002-01-01

68

UV and Solar TiO2 Photocatalysis of Brevetoxins (PbTxs)  

PubMed Central

Karenia brevis, the harmful alga associated with red tide, produces brevetoxins (PbTxs). Exposure to these toxins can have a negative impact on marine wildlife and serious human health consequences. The elimination of PbTxs is critical to protect the marine environment and human health. TiO2 photocatalysis under 350 nm and solar irradiation leads to significant degradation of PbTxs via first order kinetics. ELISA results demonstrate TiO2 photocatalysis leads to a significant decrease in the bioactivity of PbTxs as a function of treatment time. Experiments conducted in the presence of synthetic seawater, humic material and a hydroxyl scavenger showed decreased degradation. PbTxs are highly hydrophobic and partition to organic microlayer on the ocean surface. Acetonitrile was employed to probe the influence of an organic media on the TiO2 photocatalysis of PbTxs. Our results indicate TiO2 photocatalysis may be applicable for the degradation of PbTxs. PMID:19931554

Khan, Urooj; Benabderrazik, Nadia; Bourdelais, Andrea J.; Baden, Daniel G.; Rein, Kathleen; Gardinali, Piero R.; Arroyo, Luis; O’Shea, Kevin E.

2012-01-01

69

Desulfurization of Real and Model Liquid Fuels Using Light: Photocatalysis and Photochemistry  

Microsoft Academic Search

Ultra-deep desulfurization of liquid fuels is crucial for the environment, longer lifetime of combustion engines, and emerging “green,” sustainable, carbon-neutral fuels for fuel cell applications. Current interest is towards photocatalysis and photochemistry for production of clean fuels and valuable chemicals. This critical Review provides systematization and analysis of studies on photocatalytic, photosensitized, and photochemical desulfurization of liquid fuels in the

Alexander Samokhvalov

2012-01-01

70

Water Purification Systems  

NASA Technical Reports Server (NTRS)

A water purification/recycling system developed by Photo-Catalytics, Inc. (PCI) for NASA is commercially available. The system cleanses and recycles water, using a "photo-catalysis" process in which light or radiant energy sparks a chemical reaction. Chemically stable semiconductor powders are added to organically polluted water. The powder absorbs ultraviolet light, and pollutants are oxidized and converted to carbon dioxide. Potential markets for the system include research and pharmaceutical manufacturing applications, as well as microchip manufacture and wastewater cleansing.

1992-01-01

71

Degradation of pesticides chlorpyrifos, cypermethrin and chlorothalonil in aqueous solution by TiO2 photocatalysis.  

PubMed

Degradation of pesticides chlorpyrifos, cypermethrin and chlorothalonil in aqueous solution by TiO2 photocatalysis under UVA (365 nm) irradiation was examined. Enhancement of degradation and improvement in biodegradability index (BOD5/COD ratio) by H2O2 addition were also evaluated. UVA irradiation per se produced insignificant degradation of the pesticides. In UV/TiO2 photocatalysis (TiO2 1.5 g L(-1), pH 6 and 300 min irradiation), COD and TOC removal were 25.95 and 8.45%, respectively. In UV/TiO2/H2O2 photocatalysis (TiO2 1.5 g L(-1), H2O2 100 mg L(-1), pH 6 and 300 min irradiation), COD and TOC removal were 53.62 and 21.54%, respectively and biodegradability index improved to 0.26. Ammonia-nitrogen (NH3-N) decreased from 22 to 7.8 mg L(-1) and nitrate-nitrogen (NO3(-)-N) increased from 0.7 to 13.8 mg L(-1) in 300 min, indicating mineralization. Photocatalytic degradation followed pseudo-first order kinetics with rate constant (k) of 0.0025 and 0.0008 min(-1) for COD and TOC removal, respectively. FTIR spectra indicated degradation of the organic bonds of the pesticides. UV/TiO2/H2O2 photocatalysis is effective in degradation of pesticides chlorpyrifos, cypermethrin and chlorothalonil in aqueous solution. UV/TiO2/H2O2 photocatalysis may be applied as pretreatment of a chlorpyrifos, cypermethrin and chlorothalonil pesticide wastewater at pH 6, for biological treatment. PMID:24076516

Affam, Augustine Chioma; Chaudhuri, Malay

2013-11-30

72

Synergistic effect of titanium dioxide nanocrystal/reduced graphene oxide hybrid on enhancement of microbial electrocatalysis  

NASA Astrophysics Data System (ADS)

A small sized TiO2 nanocrystal (?10 nm)/reduced graphene oxide (TiO2/rGO) hybrid is synthesized through a sol-gel process for hybrid TiO2/GO followed by solvothermal reduction of GO to rGO and is further used as a microbial fuel cell (MFC) anode. The strong synergistic effect from a large surface area produced by uniformly deposited TiO2 nanocrystals, good hydrophilicity of TiO2 nanocrystals and superior conductivity of rGO leads to significantly improved electrocatalysis. In particular, a direct electrochemistry is realized by generating endogenous flavins from a large amount of microbes grown on the highly biocompatible TiO2 nanocrystals to mediate fast electron transfer between microbes and conductive rGO for a high performance anode. The TiO2/rGO hybrid anode delivers a maximum power density of 3169 mW m-2 in Shewanella putrefaciens CN32 MFC, which is much large than that of the conventional carbon cloth anode and reported TiO2/carbon hybrid anode, thus offering great potential for practical applications of MFC. This work is for the first time to report that the synergistic effect from tailoring the physical structure to achieve small sized TiO2 nanocrystals while rationally designing chemistry to introduce highly conductive rGO and superior biocompatible TiO2 is able to significantly boost the MFC performance.

Zou, Long; Qiao, Yan; Wu, Xiao-Shuai; Ma, Cai-Xia; Li, Xin; Li, Chang Ming

2015-02-01

73

Fuel cell applied research: electrocatalysis and materials. Quarterly report, October 1-December 31, 1979  

SciTech Connect

Research on electrocatalysis of phosphoric acid fuel cell reactions is reported. Five types of carbon obtained from Cabot Laboratories (Cabot designation of carbons - Monarch 1300, CSX 98, Mogul L, Vulcan XC-72R and Regan 660R) were compared as supports for platinum electrocatalysts. Experiments were conducted to determine the wetting characteristics of the carbons on the electrocatalytic activity of supported platinum for oxygen reduction. The latter was investigated by a cyclic voltammetry technique. The changes in the electrochemically active surface areas on increasing the temperature from 25/sup 0/ to 135/sup 0/C and after carrying out oxygen reduction were measured from the hydrogen desorption charge in the cyclic voltammograms. Also, research on electrode kinetics in high-temperature solid electrolyte fuel cells is described. The influence of electrode material on oxygen reduction kinetics and the reaction mechanism on platinum at interfaces with solid electrolytes were investigated. Direct current and alternating current impedance techniques were used. Studies on the oxidation of H/sub 2/ on platinum and gold interfaces with the zirconia electrolyte interface were begun. Experiments on single contact ball electrodes of platinum were used. Slow potential sweep techniques (scan rate 5 mV/sec) were used. Results are presented and discussed. (WHK)

Srinivasan, S.; Isaacs, H.S.; McBreen, J.; O'Grady, W.E.; Olender, H.; Olmer, L.J.; Schouler, E.J.L.; Kordesch, K.V.

1980-05-01

74

Electrocatalysis for oxygen electrodes in fuel cells and water electrolyzers for space applications  

NASA Technical Reports Server (NTRS)

The lead ruthenate pyrochlore Pb2Ru2O6.5, in both high- and low-area forms, has been characterized using thermogravimetric analysis, X-ray photoelectron spectroscopy, X-ray diffraction, cyclic voltammetry, and O2 reduction and generation kinetic-mechanistic studies. Mechanisms are proposed. Compounds in which part of the Ru is substituted with Ir have also been prepared. They exhibit somewhat better performance for O2 reduction in porous, gas-fed electrodes than the unsubstituted compound. The anodic corrosion resistance of pyrochlore-based porous electrodes was improved by using two different anionically conducting polymer overlayers, which slow down the diffusion of ruthenate and plumbate out of the electrode. The O2 generation performance was improved with both types of electrodes. With a hydrogel overlayer, the O2 reduction performance was also improved.

Prakash, Jai; Tryk, Donald; Yeager, Ernest

1990-01-01

75

Lanthanide-doped upconversion materials: emerging applications for photovoltaics and photocatalysis  

NASA Astrophysics Data System (ADS)

Photovoltaics and photocatalysis are two significant applications of clean and sustainable solar energy, albeit constrained by their inability to harvest the infrared spectrum of solar radiation. Lanthanide-doped materials are particularly promising in this regard, with tunable absorption in the infrared region and the ability to convert the long-wavelength excitation into shorter-wavelength light output through an upconversion process. In this review, we highlight the emerging applications of lanthanide-doped upconversion materials in the areas of photovoltaics and photocatalysis. We attempt to elucidate the fundamental physical principles that govern the energy conversion by the upconversion materials. In addition, we intend to draw attention to recent technologies in upconversion nanomaterials integrated with photovoltaic and photocatalytic devices. This review also provides a useful guide to materials synthesis and optoelectronic device fabrication based on lanthanide-doped upconversion materials.

Yang, Weifeng; Li, Xiyan; Chi, Dongzhi; Zhang, Hongjie; Liu, Xiaogang

2014-12-01

76

Recent Progress in Photocatalysis Mediated by Colloidal II-VI Nanocrystals  

PubMed Central

The use of photoexcited electrons and holes in semiconductor nanocrystals as reduction and oxidation reagents is an intriguing way of harvesting photon energy to drive chemical reactions. This review focuses on recent research efforts to understand and control the photocatalytic processes mediated by colloidal II-VI nanocrystalline materials, such as cadmium and zinc chalcogenides. First, we highlight how nanocrystal properties govern the rates and efficiencies of charge-transfer processes relevant to photocatalysis. We then describe the use of nanocrystal catalyst heterostructures for fuel-forming reactions, most commonly H2 generation. Finally, we review the use of nanocrystal photocatalysis as a synthetic tool for metal–semiconductor nano-heterostructures. PMID:24115781

Wilker, Molly B; Schnitzenbaumer, Kyle J; Dukovic, Gordana

2012-01-01

77

Band gap engineering in BiNbO{sub 4} for visible-light photocatalysis  

SciTech Connect

We have investigated the electronic structure of anionic mono- (S, N, and C) and co-doping (N-N, C-N, S-C, and S-N) on BiNbO{sub 4} for the visible-light photocatalysis. The maximum band gap reduction of pure BiNbO{sub 4} is possible with the (C-S) co-doping and minimum with N mono-doping. The calculated binding energies show that the co-doped systems are more stable than their mono-doped counterparts. Our optical absorption curves indicate that the mono- (C) and co-anionic doped (N-N and C-S) BiNbO{sub 4} systems are promising materials for visible light photocatalysis.

Wang, B. C. [Department of Materials Science and Engineering, Royal Institute of Technology (KTH), S-100 44 Stockholm (Sweden); Nisar, J.; Pathak, B. [Department of Physics and Astronomy, Box 530, Uppsala University, S-751 21 Uppsala (Sweden); Kang, T. W. [QSRC, Department of Physics, Dongguk University, Seoul 100-715 (Korea, Republic of); Ahuja, R. [Department of Materials Science and Engineering, Royal Institute of Technology (KTH), S-100 44 Stockholm (Sweden); Department of Physics and Astronomy, Box 530, Uppsala University, S-751 21 Uppsala (Sweden)

2012-04-30

78

Applicability and costs of nanofiltration in combination with photocatalysis for the treatment of dye house effluents  

PubMed Central

Summary Nanofiltration (NF) is a capable method for the separation of dyes, which can support and even improve the applicability of photocatalysis in effluent-treatment processes. The membrane process usually will need a special pre-treatment to avoid precipitation and fouling on the membrane surface. Conceptually NF can be applied in the pre-treatment prior to the catalytic reactor or in connection with the reactor to separate the liquid phase from the reaction system and to recycle finely suspended catalysts and/or organic compounds. When concerning such reaction systems on a bigger scale, cost figures will prove the usefulness of those concepts. Different applications of photocatalysis on the lab-scale have been published in recent years. Membrane technology is used almost in all those processes and an overview will be given of those recently published systems that have been reported to be potentially useful for a further scale-up. NF membranes are mostly used for the more sophisticated separation step of these processes and the additional costs of the NF treatment, without any associated equipments, will be described and illustrated. The total specific costs of industrial NF treatment processes in usefully adjusted and designed plants range from 1 to 6 US$/m3 treated effluent. Combination concepts will have a good precondition for further development and upscaling, if the NF costs discussed here in detail will be, together with the costs of photocatalysis, economically acceptable. PMID:24778974

Samhaber, Wolfgang M

2014-01-01

79

Triplet-Triplet Annihilation Upconversion in CdS-Decorated SiO2 Nanocapsules for Sub-Bandgap Photocatalysis.  

PubMed

This study reports the first successful nanoscale encapsulation of triplet-triplet annihilation upconversion (TTA-UC) medium within a rigid silica shell using a self-assembly microemulsion process. These newly synthesized nanocapsules present a few critical advances that could be instrumental for a wide range of aqueous-based photonics applications, including photocatalysis, artificial photosynthesis, and bioimaging. The nanocapsules form a homogeneous suspension that can produce intense, diffuse UC emission in water without deoxygenation, closely resembling conventional TTA-UC processes that have been performed in deoxygenated organic solvents. The silica shell provides sites for further surface modification, which allows, when combined with its nanoscale dimension and structural rigidity, this TTA-UC system to acquire various useful functionalities. A benchmark TTA-UC pair, palladium(II) tetraphenyltetrabenzoporphyrin as a sensitizer and perylene as an acceptor, was used to demonstrate efficient red-to-blue (635 nm, 1.95 eV ? 470 nm, 2.6 eV) upconversion in the oxygen-rich aqueous phase. The nanocapsule surface was further functionalized with cadmium sulfide nanoparticles (Eg = 2.4 eV) to demonstrate sub-bandgap sensitization and subsequent aqueous-phase catalytic oxidation. PMID:25522373

Kwon, Oh Seok; Kim, Jae-Hyuk; Cho, Jin Ku; Kim, Jae-Hong

2015-01-14

80

Nickel removal by biosorption onto medlar male flowers coupled with photocatalysis on the spinel ZnMn2O4.  

PubMed

Ni2+ is a highly toxic above 0.07 mg/L and its removal is of high significance. The biosorption of Ni2+ onto medlar male flowers (MMF) was studied in relation with the physical parameters like pH, contact time, biosorbent dosage, Ni2+ concentration and temperature. The interaction biosorbent-Ni2+ was examined by the FTIR technique. The equilibrium was achieved within 40 min and the data were well fitted by the Langmuir and Redlich-Peterson (R-P) models. The maximum Ni2+ uptake capacity was 17.073 mg/g at 25°C and the Ni2+ removal follows a pseudo-second order kinetic with activation energy of 13.3 kJ/mol. The thermodynamic parameters: ?S°, ?H° and ?G° showed that the biosorption was spontaneous and endothermic. MMF was used as a post treatment technique and the biosorption was coupled with the visible light driven Ni2+ reduction over the spinel ZnMn2O4. The effect of the pH, ZnMn2O4 loading and light intensity on the photoactivity was investigated. 77.5% of Ni2+ was reduced after ~140 min under optimal conditions. The Ni2+ removal reached a rate conversion of 96% of with the coupled system biosorption/photocatalysis is very promising for the water treatment. PMID:24401700

Chergui, Ahmed; Madjene, Farid; Trari, Mohamed; Khouider, Ali

2014-01-01

81

Photocatalytic treatment of water-soluble pesticides by photo-Fenton and TiO 2 using solar energy  

Microsoft Academic Search

The technical feasibility and performance of photocatalytic degradation of four water-soluble pesticides (diuron, imidacloprid, formetanate and methomyl) have been studied at pilot scale in two well-defined systems of special interest because natural-solar UV light can be used: heterogeneous photocatalysis with titanium dioxide and homogeneous photocatalysis by photo-Fenton. The pilot plant is made up of compound parabolic collectors (CPCs) specially designed

S Malato; J Blanco; J Cáceres; A. R Fernández-Alba; A Agüera; A Rodr??guez

2002-01-01

82

Production of Hydrogen by Electrocatalysis: Making the H-H Bond by Combining Protons and Hydrides  

SciTech Connect

Generation of hydrogen by reduction of two protons by two electrons can be catalysed by molecular electrocatalysts. Determination of the thermodynamic driving force for elimination of H2 from molecular complexes is important for the rational design of molecular electrocatalysts, and allows the design of metal complexes of abundant, inexpensive metals rather than precious metals (“Cheap Metals for Noble Tasks”). The rate of H2 evolution can be dramatically accelerated by incorporating pendant amines into diphosphine ligands. These pendant amines in the second coordination sphere function as protons relays, accelerating intramolecular and intermolecular proton transfer reactions. The thermodynamics of hydride transfer from metal hydrides and the acidity of protonated pendant amines (pKa of N-H) contribute to the thermodynamics of elimination of H2; both of the hydricity and acidity can be systematically varied by changing the substituents on the ligands. A series of Ni(II) electrocatalysts with pendant amines have been developed. In addition to the thermochemical considerations, the catalytic rate is strongly influenced by the ability to deliver protons to the correct location of the pendant amine. Protonation of the amine endo to the metal leads to the N-H being positioned appropriately to favor rapid heterocoupling with the M-H. Designing ligands that include proton relays that are properly positioned and thermodynamically tuned is a key principle for molecular electrocatalysts for H2 production as well as for other multi-proton, multi-electron reactions important for energy conversions. The research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for DOE.

Bullock, R. Morris; Appel, Aaron M.; Helm, Monte L.

2014-03-25

83

Heterogeneous Photocatalysis as an Advanced Oxidation Process for the Abatement of Chlorinated, Monocyclic Aromatic and Sulfurous Volatile Organic Compounds in Air: State of the Art  

Microsoft Academic Search

This review focuses on both fundamentals and applicability of heterogeneous photocatalysis as an advanced oxidation technology for degradation of volatile organic compounds (VOC) in air, with peer-reviewed literature data published since 1997 being the backbone of this article. Four key issues are covered. First, the underlying principles of heterogeneous photocatalysis are outlined using the band gap model. Second, a detailed

Kristof Demeestere; Jo Dewulf; Herman Van Langenhove

2007-01-01

84

Oxidation of nauseous sulfur compounds by photocatalysis or photosensitization  

Microsoft Academic Search

Reduced sulfur compounds such as methanethiol (MSH), dimethylsulfide (DMS) and dimethydisulfide (DMDS) are nauseous by-products produced by a great number of industrial processes. Oxidation of these reduced sulfur compounds in polluted atmospheres and hence the decrease of their harmful and malodorous effects is thus a matter of concern in numerous industrial and water treatment plants. Photocatalytic treatment of gaseous flow

C. Cantau; S. Larribau; T. Pigot; M. Simon; M. T. Maurette; S. Lacombe

2007-01-01

85

Identification of Plant Growth-Promoting Bacteria Using Titanium Dioxide Photocatalysis-Assisted Photoacoustic Technique  

NASA Astrophysics Data System (ADS)

The effect of titanium dioxide photocatalysis against bacteria that are dangerous for human health has been investigated in the past, suggesting the possibility of using a specific behavior for each microorganism during this process for its discrimination. In this study, the behavior of some plants’ growth promoting bacteria ( Burkholderia unamae (Strain MTI 641), Acetobacter diazotrophicus (Strain PAl 5T), A. diazotrophicus (Strain CFN-Cf 52), and B. unamae (Strain TATl-371)) interacting with light and bactericidal titanium dioxide films have been analyzed using the photoacoustic technique. The monitoring of these interactions shows particular characteristics that could serve for identifying these species.

Gordillo-Delgado, F.; Marín, E.; Calderón, A.

2013-09-01

86

Enhanced degradation efficiency of toluene using titania/silica photocatalysis as a regeneration process.  

PubMed

Three kinds of titania/silica pellets were prepared using the sol-gel method with surface areas of 50.4 m2 g(-1), 421.1 m2 x g(-1) and 89.1 m2 x g(-1). An annular reactor was designed and built to determine the degradation efficiency of toluene and to investigate the relationship between the adsorption and desorption-photocatalytic processes. Surface area is an important factor influencing the adsorption-photocatalytic efficiency. Higher surface areas of pellets contribute to high rates of conversion of toluene. Un-reacted toluene and reaction intermediates accumulating on their surface deactivated the titania/silica catalyst. To overcome this problem, the adsorption and regeneration process were alternated in a dual reactor system. Connecting or disconnecting the toluene feed gas enabled one reactor to adsorb toluene, while the second reactor was regenerated by photocatalysis. Using UV irradiation and titania/silica pellets with high BET surface area (421.1 m2 x g(-1)), the alternating adsorption/regeneration processes kept the degradation efficiency of toluene at 90% after 8 hours operation. By improving the adsorption-photocatalysis efficiency, and minimising the generation and accumulation of intermediate on the surface of pellets, the method extended catalyst life and maintained a high degradation efficiency of toluene. PMID:16583820

Luo, Y; Zou, L; Hu, E

2006-04-01

87

UV-absorption--the primary process in photocatalysis and some practical consequences.  

PubMed

TiO2 photochemistry studies generally address reactions of photogenerated charge-carriers at the oxide surface or the recombination reactions which control the proportion of charge carriers that reach the surface. By contrast, this review focuses on UV absorption, the first photochemical step in semiconductor photocatalysis. The influence of particle size on absorption and scattering of light by small TiO2 particles is summarized and the importance of considering, the particle size in the application, not the BET or X-ray line broadening size, is emphasized. Three different consequences of UV absorption are then considered. First, two commercially important systems, pigmented polymer films and paints, are used to show that TiO2 can protect from direct photochemical degradation. Then the effect of UV absorption on the measured photocatalytic degradation of aqueous solutions of organics is considered for two separate cases. Firstly, the consequences of UV absorption by TiO2 on the generation of hydroxyl radicals from H2O2 are considered in the context of the claimed synergy between H2O2 and TiO2. Secondly, the effect of altered UV absorption, caused by changed effective particle size of the catalyst, is demonstrated for photocatalysis of propan-2-ol oxidation and salicylic acid degradation. PMID:25383755

Egerton, Terry A

2014-01-01

88

A new metal-free carbon hybrid for enhanced photocatalysis.  

PubMed

Carbon nitride (C3N4) is a layered, stable, and polymeric metal-free material that has been discovered as a visible-light-response photocatalyst. Owing to C3N4 having a higher conduction band position, most previous studies have been focused on its reduction capability for solar fuel production, such as hydrogen generation from water splitting or hydrocarbon production from CO2. However, photooxidation ability of g-C3N4 is weak and has been less explored, especially for decomposition of chemically stable phenolics. Carbon spheres prepared by a hydrothermal carbonization of glucose have been widely applied as a support material or template due to their interesting physicochemical properties and the functional groups on the reactive surface. This study demonstrated that growth of carbon nanospheres onto g-C3N4 (CN-CS) can significantly increase the photooxidation ability (to about 4.79 times higher than that of pristine g-C3N4) in phenol degradation under artificial sunlight irradiations. The crystal structure, optical property, morphology, surface groups, recombination rate of electron/hole pairs, and thermal stability of CN-CS were investigated by a variety of characterization techniques. This study contributes to the further promising applications of carbon nitride in metal-free catalysis. PMID:25212502

Sun, Hongqi; Zhou, Guanliang; Wang, Yuxian; Suvorova, Alexandra; Wang, Shaobin

2014-10-01

89

Enhancement of titanium dioxide photocatalysis with polyhydroxy fullerenes  

NASA Astrophysics Data System (ADS)

Semiconductor photocatalysts, particularly TiO2, are attracting extensive research for destruction of environmentally hazardous chemicals (e.g., organic pollutants, greenhouse gases) and hazardous bioparticulates (e.g., bacterial endospores, emerging pathogens) because they can achieve complete mineralization without generation of toxic byproducts. Several attempts have been made to improve the quantum efficiency of TiO2 by conjugating it with conductors such as metals and organic molecules for scavenging the photo-generated electrons. Another class of materials well known for their electron accepting properties is carbon nanotubes and fullerenes. TiO2 (anatase polymorph) was coated on multi-wall carbon nanotubes by sol-gel coating and the resulting nanocomposites were found to inactivate bacterial endospores two times faster than Degussa P25 (gold standard), but were ineffective against Escherichia coli. This was attributed to their high aspect ratio, which prevented contact with the fimbriae covered cell-wall of E. coli. Water-soluble and non-toxic polyhydroxy fullerenes (PHF) were employed as alternate to the TiO2 coated MWNT. Adsorption of PHF molecules onto TiO2 by electrostatic interaction was demonstrated. PHF-TiO 2 nanocomposites enhanced the photocatalytic activity of TiO2 for dye degradation and E. coli inactivation. Surface coverage of TiO2 nanoparticles by PHF molecules determined the extent of enhancement, with an optimum at 2--7% surface coverage. The rate of photocatalytic dye degradation by the TiO2-PHF nanocomposite was 2.6 times the rate found with TiO2 alone. The hypothesis that scavenging of photo-generated electrons and therefore higher generation of hydroxyl radicals is the mechanism for the observed enhancement was validated. The concentration of hydroxyl radicals generated by PHF-TiO 2 nanocomposite was up to 60% greater than the concentration obtained with TiO2 alone as determined with EPR. Influence of functional groups of PHF on its electron scavenging ability and stability was determined. Fresh and aged forms of PHF were characterized by MS, FTIR, XPS and TGA. Higher concentrations of impure groups were detrimental to stability and electron scavenging ability of PHF. A ratio of impure groups to hydroxyl groups of 0.27 was associated with successful enhancement by PHF, whereas a ratio of 1.66 was associated with no enhancement. Guidelines for effective formulation of PHF-TiO2 nanocomposites were developed.

Krishna, Vijay B.

2007-05-01

90

Hierarchical synthesis of non-centrosymmetric hybrid nanostructures and enabled plasmon-driven photocatalysis.  

PubMed

Non-centrosymmetric nanostructures consisting of multiple functional subunits represents an emerging class of hybrid nanostructures that can possess dramatic difference in property and functionality from concentric core-shell configuration. Here we develop a general synthetic method to achieve hierarchical control of high-order non-centrosymmetric hybrid nanostructures. The key is to employ a common intermedium for sequential conversion to all distinct predesigned subunits under similar growth condition, thus facilitating manifold control of a hybrid nanostructure. This advancement leads to an optimally designed plasmon-mediated photocatalytic nanostructure with 14.8-fold enhancement of photocatalytic efficiency as compared with conventional photocatalysts. Mechanistic study involving theoretical modelling and ultrafast time-resolved optical measurement uncovers a hot plasmonic electron-driven photocatalysis mechanism with an identified electron transfer pathway. This study may represent an important step towards high-level control of artificial nanostructures with new horizons for fundamental and technological applications. PMID:25178269

Weng, Lin; Zhang, Hui; Govorov, Alexander O; Ouyang, Min

2014-01-01

91

Nanostructure sensitization of transition metal oxides for visible-light photocatalysis  

PubMed Central

Summary To better utilize the sunlight for efficient solar energy conversion, the research on visible-light active photocatalysts has recently attracted a lot of interest. The photosensitization of transition metal oxides is a promising approach for achieving effective visible-light photocatalysis. This review article primarily discusses the recent progress in the realm of a variety of nanostructured photosensitizers such as quantum dots, plasmonic metal nanostructures, and carbon nanostructures for coupling with wide-bandgap transition metal oxides to design better visible-light active photocatalysts. The underlying mechanisms of the composite photocatalysts, e.g., the light-induced charge separation and the subsequent visible-light photocatalytic reaction processes in environmental remediation and solar fuel generation fields, are also introduced. A brief outlook on the nanostructure photosensitization is also given. PMID:24991507

Chen, Hongjun

2014-01-01

92

TiO2 photocatalysis damages lipids and proteins in Escherichia coli.  

PubMed

This study investigates the mechanisms of UV-A (315 to 400 nm) photocatalysis with titanium dioxide (TiO2) applied to the degradation of Escherichia coli and their effects on two key cellular components: lipids and proteins. The impact of TiO2 photocatalysis on E. coli survival was monitored by counting on agar plate and by assessing lipid peroxidation and performing proteomic analysis. We observed through malondialdehyde quantification that lipid peroxidation occurred during the photocatalytic process, and the addition of superoxide dismutase, which acts as a scavenger of the superoxide anion radical (O2·(-)), inhibited this effect by half, showing us that O2·(-) radicals participate in the photocatalytic antimicrobial effect. Qualitative analysis using two-dimensional electrophoresis allowed selection of proteins for which spot modifications were observed during the applied treatments. Two-dimensional electrophoresis highlighted that among the selected protein spots, 7 and 19 spots had already disappeared in the dark in the presence of 0.1 g/liter and 0.4 g/liter TiO2, respectively, which is accounted for by the cytotoxic effect of TiO2. Exposure to 30 min of UV-A radiation in the presence of 0.1 g/liter and 0.4 g/liter TiO2 increased the numbers of missing spots to 14 and 22, respectively. The proteins affected by photocatalytic oxidation were strongly heterogeneous in terms of location and functional category. We identified several porins, proteins implicated in stress response, in transport, and in bacterial metabolism. This study reveals the simultaneous effects of O2·(-) on lipid peroxidation and on the proteome during photocatalytic treatment and therefore contributes to a better understanding of molecular mechanisms in antibacterial photocatalytic treatment. PMID:24532071

Carré, Gaëlle; Hamon, Erwann; Ennahar, Saïd; Estner, Maxime; Lett, Marie-Claire; Horvatovich, Peter; Gies, Jean-Pierre; Keller, Valérie; Keller, Nicolas; Andre, Philippe

2014-04-01

93

TiO2 Photocatalysis Damages Lipids and Proteins in Escherichia coli  

PubMed Central

This study investigates the mechanisms of UV-A (315 to 400 nm) photocatalysis with titanium dioxide (TiO2) applied to the degradation of Escherichia coli and their effects on two key cellular components: lipids and proteins. The impact of TiO2 photocatalysis on E. coli survival was monitored by counting on agar plate and by assessing lipid peroxidation and performing proteomic analysis. We observed through malondialdehyde quantification that lipid peroxidation occurred during the photocatalytic process, and the addition of superoxide dismutase, which acts as a scavenger of the superoxide anion radical (O2·?), inhibited this effect by half, showing us that O2·? radicals participate in the photocatalytic antimicrobial effect. Qualitative analysis using two-dimensional electrophoresis allowed selection of proteins for which spot modifications were observed during the applied treatments. Two-dimensional electrophoresis highlighted that among the selected protein spots, 7 and 19 spots had already disappeared in the dark in the presence of 0.1 g/liter and 0.4 g/liter TiO2, respectively, which is accounted for by the cytotoxic effect of TiO2. Exposure to 30 min of UV-A radiation in the presence of 0.1 g/liter and 0.4 g/liter TiO2 increased the numbers of missing spots to 14 and 22, respectively. The proteins affected by photocatalytic oxidation were strongly heterogeneous in terms of location and functional category. We identified several porins, proteins implicated in stress response, in transport, and in bacterial metabolism. This study reveals the simultaneous effects of O2·? on lipid peroxidation and on the proteome during photocatalytic treatment and therefore contributes to a better understanding of molecular mechanisms in antibacterial photocatalytic treatment. PMID:24532071

Hamon, Erwann; Ennahar, Saïd; Estner, Maxime; Lett, Marie-Claire; Horvatovich, Peter; Gies, Jean-Pierre; Keller, Valérie; Andre, Philippe

2014-01-01

94

PHOTOCATALYTIC OXIDATION OF METHYL-TERT-BUTYL ETHER FOR DRINKING WATER TREATMENT  

EPA Science Inventory

The photo-oxidation of methyl tert-butyl ether (MTBE) in water was investigated to determine the feasibility of using photocatalysis for the treatment of MTBE-contaminated drinking water. The feasibility assessment was conducted using slurries of titanium dioxide in both a photo-...

95

Removal of selected persistent organic pollutants by heterogeneous photocatalysis in water  

Microsoft Academic Search

Environmentally relevant polar persistent organic pollutants (pharmaceuticals and diagnostic agents) were chosen according to human consumption and occurrence in the aquatic environment (sewage plant effluents, rivers and groundwater) to investigate their behavior during photocatalytic oxidation. From data compilation in the literature, the active metabolite clofibric acid of some lipid lowering agents, the anti-epileptic drug carbamazepine and the X-ray contrast media

Tusnelda E. Doll; Fritz H. Frimmel

2005-01-01

96

Theory and Experiments for Voltammetric and SECM Investigations and Application to ORR Electrocatalysis at Nanoelectrode Ensembles of Ultramicroelectrode Dimensions.  

PubMed

Theoretical and experimental approaches to characterizing nanoelectrode (NE) ensembles of ultramicroelectrode dimensions (UME-NEEs) as a function of fraction of active area and random NE distribution are described. UME-NEEs were fabricated by addressing microregions of a gold-filled polycarbonate membrane through the UMEs of an underlying microfabricated addressable array. Results of Comsol Multiphysics 3D simulations based on randomly spaced NEs of 15 nm radius on a UME disk geometry of radii up to 5 ?m are shown for steady-state voltammetry (SSV) and scanning electrochemical microscopy (SECM) experiments. Analytical equations were developed to describe the diffusion-limited steady-state current and steady-state voltammogram at an UME-NEE. These equations are shown to be in good agreement with the simulations and enabled evaluation of experimental SSVs. Comparison of experimental and simulated SECM approach curves, images, and tip voltammograms enabled the fraction of active area and distribution of NEs to be visualized and determined for individual UME-NEEs. Gold UME-NEEs are shown to be unique platforms for electrodeposition in forming nanoparticle electrodes (UME-NPEs). Electrocatalysis results for the oxygen reduction reaction (ORR) on Pt UME-NPEs in 0.1 M H2SO4 are also shown. PMID:25495486

Fernández, José L; Wijesinghe, Manjula; Zoski, Cynthia G

2015-01-20

97

Lignin depolymerization and upgrading via fast pyrolysis and electrocatalysis for the production of liquid fuels and value-added products  

NASA Astrophysics Data System (ADS)

The production of liquid hydrocarbon fuels from biomass is needed to replace fossil fuels, which are decreasing in supply at an unsustainable rate. Renewable fuels also address the rising levels of greenhouse gases, an issue for which the Intergovernmental Panel on Climate Change implicated humanity in 2013. In response, the Energy Independence and Security Act (EISA) mandates the production of 21 billion gallons of advanced biofuels by 2022. Biomass fast pyrolysis (BFP) uses heat (400-600 °C) without oxygen to convert biomass to liquids fuel precursors offering an alternative to fossil fuels and a means to meet the EISA mandate. The major product, bio-oil, can be further upgraded to liquid hydrocarbon fuels, while biochar can serve as a solid fuel or soil amendment. The combustible gas co-product is typically burned for process heat. Though the most valuable of the pyrolysis products, the liquid bio-oil is highly oxygenated, corrosive, low in energy content and unstable during storage. As a means of improving bio-oil properties, electrocatalytic hydrogenation (ECH) is employed to reduce and deoxygenate reactive compounds. This work specifically focuses on lignin as a feed material for BFP. As lignin comprises up to 30% of the mass and 40% of the energy stored in biomass, it offers great potential for the production of liquid fuels and value-added products by utilizing fast pyrolysis as a conversion method coupled with electrocatalysis as an upgrading method.

Garedew, Mahlet

98

Direct electrochemistry and electrocatalysis of heme proteins entrapped in agarose hydrogel films in room-temperature ionic liquids.  

PubMed

The electrochemistry and electrocatalysis of a number of heme proteins entrapped in agarose hydrogel films in the room-temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF(6)]) have been investigated. UV-vis and FTIR spectroscopy show that the heme proteins retain their native structure in agarose film. The uniform distribution of hemoglobin in agarose-dimethylformamide film was demonstrated by atomic force microscopy. Cyclic voltammetry shows that direct electron transfer between the heme proteins and glassy carbon electrode is quasi-reversible in [bmim][PF(6)]. The redox potentials for hemoglobin, myoglobin, horseradish peroxidase, cytochrome c, and catalase were found to be more negative than those in aqueous solution. The charge-transfer coefficient and the apparent electron-transfer rate constant for these heme proteins in [bmim][PF(6)] were calculated from the peak-to-peak separation as a function of scan rate. The heme proteins catalyze the electroreduction of trichloroacetic acid and tert-butyl hydroperoxide in [bmim][PF(6)]. The kinetic parameter I(max) (maximum current at saturation concentration of substrate) and the apparent K(m) (Michaelis-Menten constant) for the electrocatalytic reactions were evaluated. PMID:16171360

Wang, Sheng-Fu; Chen, Ting; Zhang, Zhi-Ling; Shen, Xin-Cheng; Lu, Zhe-Xue; Pang, Dai-Wen; Wong, Kwok-Yin

2005-09-27

99

Preparation and Photocatalysis Properties of Bacterial Cellulose\\/TiO2 Composite Membrane Doped with Rare Earth Elements  

Microsoft Academic Search

Bacterial cellulose (BC) was chosen as a support for nanometer titanium dioxide (TiO2) particles due to its superfine network structure. The composite membrane of TiO2\\/BC doped with rare earth elements was prepared by a sol-gel method using tetraisopropyl titanate as starting material. Photocatalysis properties of this composite membrane were estimated by using methyl orange as a degradation agent. X-ray fluorescence

Xiuju Zhang; Wenbin Chen; Zhidan Lin; Jia Yao; Shaozao Tan

2011-01-01

100

Controlled Preparation of Porous TiO2 -Ag Nanostructures through Supramolecular Assembly for Plasmon-Enhanced Photocatalysis.  

PubMed

By templating Ag(+) -induced supramolecular assembly at different temperatures, porous TiO2 -Ag nanotubes and nanospheres are fabricated in a controlled manner due to the effect of Rayleigh instability. Compared with traditional TiO2 nanoparticles, TiO2 -Ag nanostructures above show much more extensive visible light absorption and exhibit the noticeably plasmon-enhanced photocatalysis because of the existence of Ag nanoparticles. PMID:25382153

Fei, Jinbo; Li, Junbai

2015-01-01

101

Correlation of electron transport and photocatalysis of nanocrystalline clusters studied by Monte-Carlo continuity random walking.  

PubMed

In this research, Monte-Carlo Continuity Random Walking (MC-RW) model was used to study the relation between electron transport and photocatalysis of nano-crystalline (nc) clusters. The effects of defect energy disorder, spatial disorder of material structure, electron density, and interfacial transfer/recombination on the electron transport and the photocatalysis were studied. Photocatalytic activity is defined as 1/? from a statistical viewpoint with ? being the electron average lifetime. Based on the MC-RW simulation, a clear physical and chemical "picture" was given for the photocatalytic kinetic analysis of nc-clusters. It is shown that the increase of defect energy disorder and material spatial structural disorder, such as the decrease of defect trap number, the increase of crystallinity, the increase of particle size, and the increase of inter-particle connection, can enhance photocatalytic activity through increasing electron transport ability. The increase of electron density increases the electron Fermi level, which decreases the activation energy for electron de-trapping from traps to extending states, and correspondingly increases electron transport ability and photocatalytic activity. Reducing recombination of electrons and holes can increase electron transport through the increase of electron density and then increases the photocatalytic activity. In addition to the electron transport, the increase of probability for electrons to undergo photocatalysis can increase photocatalytic activity through the increase of the electron interfacial transfer speed. PMID:25608276

Liu, Baoshun; Li, Ziqiang; Zhao, Xiujian

2015-02-01

102

Plasmonic photocatalysis properties of Au nanoparticles precipitated anatase/rutile mixed TiO2 nanotubes.  

PubMed

Anatase/rutile mixed titania nanotubes (TiO2 NTs) precipitated with gold nanoparticles (Au NPs), i.e. Au/TiO2, have been synthesized and investigated on visible photocatalysis properties. A deposition-precipitation (DP) method was adopted to reduce the gold precursor to Au NPs within the preformed TiO2 NTs by the emulsion electrospinning technique. The optimal visible photocatalytic activity was found in the sample Au3(DP350)/TiO2 with a loading of 3 wt% Au NPs and calcining at 350 °C. Through transmission electron microscopy, Au NPs of 4.16 nm diameter were observed at the interface between the anatase and rutile phases in the optimal Au3(DP350)/TiO2 sample, and these joint active sites at the interface were beneficial for charge separation. The obtained optimal photocatalytic efficiency of Au3(DP350)/TiO2 was ascribed to the synergistic effect of the enhanced visible absorption and the anatase/rutile mixed-phase composition, and the possible mechanism for this was discussed in detail. PMID:23963545

Wen, Yan; Liu, Bitao; Zeng, Wei; Wang, Yuhua

2013-10-21

103

Synthesis of nanotitania decorated few-layer graphene for enhanced visible light driven photocatalysis.  

PubMed

We report a simple method for decorating carboxyl functionalized few-layer graphene with titania (TiO2) nanoparticles by sonication and stirring under room temperature. The nanocomposites showed a remarkable improvement in visible light driven photocatalysis. From Raman and XRD analysis the number of layers of graphene was found to be 3. The TiO2 decorated few-layer graphene (FLG) sheets were characterized by electron microscopy, Raman spectroscopy, infrared spectroscopy, XRD and UV-vis spectroscopy. Titania nanoparticles were uniformly decorated on FLG matrix. The incorporation of titania on FLG enhanced the visible light photocatalytic activity of titania, lowered the electron hole recombination and improved the electron hole mobility. The enhanced life time of the charge carriers was confirmed from the photocurrent measurements. Compared to bare TiO2 nanoparticles the FLG-TiO2 nanocomposites exhibited rapid degradation of Rhodamine B (Rhd B) under solar radiation. It was found that adsorption of dye molecules and the rate of degradation have been greatly enhanced in the FLG decorated with TiO2. The rapid degradation of Rhd B using carboxyl functionalized FLG-TiO2 within 8 min under solar radiation and 20 min under 30 W UV tube with very low concentration (0.01 wt.%) of the photocatalyst is the highlight of the present report. The mechanism of degradation and charge separation ability of the nanocomposite are also explored. PMID:24910056

Thomas, Reny Thankam; Abdul Rasheed, P; Sandhyarani, N

2014-08-15

104

Sequential use of bentonites and solar photocatalysis to treat winery wastewater.  

PubMed

The sequential use of low-cost adsorbent bentonites and solar photocatalysis to treat winery wastewater has been studied. Three commercial sodium-bentonites (MB-M, MB-G, and MB-P) and one calcium-bentonite (Bengel) were characterized and used in this study. These clay materials were useful to totally remove turbidity (90-100%) and, to a lesser extent, color, polyphenols (PPh), and soluble chemical oxygen demand (CODS) from winery wastewater. Both surface area and cation exchange capacity (CEC) of bentonite had a positive impact on treatment efficiency. The effect of pH on turbidity removal by bentonites was studied in the 3.5-12 pH range. The bentonites were capable of greatly removing turbidity from winery wastewater at pH 3.5-5.5, but removal efficiency decreased with pH increase beyond this range. Settling characteristics (i.e., sludge volume index (SVI) and settling rate) of bentonites were also studied. Best settling properties were observed for bentonite doses around 0.5 g/L. The reuse of bentonite for winery wastewater treatment was found not to be advisable as the turbidity and PPh removal efficiencies decreased with successive uses. The resulting wastewater after bentonite treatment was exposed to solar radiation at oxic conditions in the presence of Fe(III) and Fe(III)/H2O2 catalysts. Significant reductions of COD, total organic carbon (TOC), and PPh were achieved by these solar photocatalytic processes. PMID:19035643

Rodríguez, Eva; Márquez, Gracia; Carpintero, Juan Carlos; Beltrán, Fernando J; Alvarez, Pedro

2008-12-24

105

Enhanced near-infrared photocatalysis of NaYF4:Yb, Tm/CdS/TiO2 composites.  

PubMed

The previous works by our group (Chem. Commun., 2010, 46, 2304-2306; ACS Catal., 2013, 3, 405-412; Phys. Chem. Chem. Phys., 2013, 15, 14681-14688) have reported the near-infrared-driven photocatalysis of broadband semiconductor TiO2 or ZnO that was combined with upconverting luminescence particles to form a core-shell structure. However, the photocatalytic efficiency is low for this new type of photocatalysts. In this work, NaYF4:Yb,Tm/CdS/TiO2 composites for NIR photocatalysis were prepared by linking CdS and TiO2 nanocrystals on the NaYF4:Yb,Tm microcrystal surfaces. CdS and TiO2 were well interacted to form a heterojunction structure. The energy transfer between NaYF4:Yb,Tm and the semiconductors CdS and TiO2 was investigated by steady-state and dynamic fluorescence spectroscopy. The photocatalytic activities of the as-prepared composites were evaluated by the degradation of methylene blue in aqueous solution upon NIR irradiation. Significantly, it was found that the united adhesions of CdS and TiO2 on the NaYF4:Yb,Tm particle surfaces showed much higher catalytic activities than the individual adhesion of CdS or TiO2 on the NaYF4:Yb,Tm surfaces. This was attributed mainly to the effective separation of the photogenerated electron-hole pairs due to the charge transfer across the CdS-TiO2 interface driven by the band potential difference between them. The presented composite structure of upconverting luminescence materials coupled with narrow/wide semiconductor heterojunctions provides a new model for improved NIR photocatalysis. PMID:24162269

Guo, Xingyuan; Di, Weihua; Chen, Changfeng; Liu, Chunxu; Wang, Xue; Qin, Weiping

2014-01-21

106

Nanoscale nickel oxide/nickel heterostructures for active hydrogen evolution electrocatalysis.  

PubMed

Active, stable and cost-effective electrocatalysts are a key to water splitting for hydrogen production through electrolysis or photoelectrochemistry. Here we report nanoscale nickel oxide/nickel heterostructures formed on carbon nanotube sidewalls as highly effective electrocatalysts for hydrogen evolution reaction with activity similar to platinum. Partially reduced nickel interfaced with nickel oxide results from thermal decomposition of nickel hydroxide precursors bonded to carbon nanotube sidewalls. The metal ion-carbon nanotube interactions impede complete reduction and Ostwald ripening of nickel species into the less hydrogen evolution reaction active pure nickel phase. A water electrolyzer that achieves ~20?mA?cm(-2) at a voltage of 1.5?V, and which may be operated by a single-cell alkaline battery, is fabricated using cheap, non-precious metal-based electrocatalysts. PMID:25146255

Gong, Ming; Zhou, Wu; Tsai, Mon-Che; Zhou, Jigang; Guan, Mingyun; Lin, Meng-Chang; Zhang, Bo; Hu, Yongfeng; Wang, Di-Yan; Yang, Jiang; Pennycook, Stephen J; Hwang, Bing-Joe; Dai, Hongjie

2014-01-01

107

Nanoscale nickel oxide/nickel heterostructures for active hydrogen evolution electrocatalysis  

NASA Astrophysics Data System (ADS)

Active, stable and cost-effective electrocatalysts are a key to water splitting for hydrogen production through electrolysis or photoelectrochemistry. Here we report nanoscale nickel oxide/nickel heterostructures formed on carbon nanotube sidewalls as highly effective electrocatalysts for hydrogen evolution reaction with activity similar to platinum. Partially reduced nickel interfaced with nickel oxide results from thermal decomposition of nickel hydroxide precursors bonded to carbon nanotube sidewalls. The metal ion-carbon nanotube interactions impede complete reduction and Ostwald ripening of nickel species into the less hydrogen evolution reaction active pure nickel phase. A water electrolyzer that achieves ~20?mA?cm-2 at a voltage of 1.5?V, and which may be operated by a single-cell alkaline battery, is fabricated using cheap, non-precious metal-based electrocatalysts.

Gong, Ming; Zhou, Wu; Tsai, Mon-Che; Zhou, Jigang; Guan, Mingyun; Lin, Meng-Chang; Zhang, Bo; Hu, Yongfeng; Wang, Di-Yan; Yang, Jiang; Pennycook, Stephen J.; Hwang, Bing-Joe; Dai, Hongjie

2014-08-01

108

Assessment of solar driven TiO2-assisted photocatalysis efficiency on amoxicillin degradation.  

PubMed

The objective of this work was to evaluate the efficiency of a solar TiO2-assisted photocatalytic process on amoxicillin (AMX) degradation, an antibiotic widely used in human and veterinary medicine. Firstly, solar photolysis of AMX was compared with solar photocatalysis in a compound parabolic collectors pilot scale photoreactor to assess the amount of accumulated UV energy in the system (Q UV) necessary to remove 20 mg L(-1) AMX from aqueous solution and mineralize the intermediary by-products. Another experiment was also carried out to accurately follow the antibacterial activity against Escherichia coli DSM 1103 and Staphylococcus aureus DSM 1104 and mineralization of AMX by tracing the contents of dissolved organic carbon (DOC), low molecular weight carboxylate anions, and inorganic anions. Finally, the influence of individual inorganic ions on AMX photocatalytic degradation efficiency and the involvement of some reactive oxygen species were also assessed. Photolysis was shown to be completely ineffective, while only 3.1 kJUV?L(-1) was sufficient to fully degrade 20 mg L(-1) AMX and remove 61% of initial DOC content in the presence of the photocatalyst and sunlight. In the experiment with an initial AMX concentration of 40 mg L(-1), antibacterial activity of the solution was considerably reduced after elimination of AMX to levels below the respective detection limit. After 11.7 kJUV?L(-1), DOC decreased by 71%; 30% of the AMX nitrogen was converted into ammonium and all sulfur compounds were converted into sulfate. A large percentage of the remaining DOC was in the form of low molecular weight carboxylic acids. Presence of phosphate ions promoted the removal of AMX from solution, while no sizeable effects on the kinetics were found for other inorganic ions. Although the AMX degradation was mainly attributed to hydroxyl radicals, singlet oxygen also plays an important role in AMX self-photosensitization under UV/visible solar light. PMID:23900954

Pereira, João H O S; Reis, Ana C; Nunes, Olga C; Borges, Maria T; Vilar, Vítor J P; Boaventura, Rui A R

2014-01-01

109

Water  

E-print Network

Explore Australia’s most comprehensive water information resource. The National Water Account provides the following information for nine nationally significant regions: • total water resource • water available for extraction • rights to abstract water • actual abstraction of water.

Quick Link

110

Development of Novel Electrode Materials for the Electrocatalysis of Oxygen-Transfer and Hydrogen-Transfer Reactions  

SciTech Connect

Throughout this thesis, the fundamental aspects involved in the electrocatalysis of anodic O-transfer reactions and cathodic H-transfer reactions have been studied. The investigation into anodic O-transfer reactions at undoped and Fe(III)[doped MnO{sub 2} films] revealed that MnO{sub 2} film electrodes prepared by a cycling voltammetry deposition show improved response for DMSO oxidation at the film electrodes vs. the Au substrate. Doping of the MnO{sub 2} films with Fe(III) further enhanced electrode activity. Reasons for this increase are believed to involve the adsorption of DMSO by the Fe(III) sites. The investigation into anodic O-transfer reactions at undoped and Fe(III)-doped RuO{sub 2} films showed that the Fe(III)-doped RuO{sub 2}-film electrodes are applicable for anodic detection of sulfur compounds. The Fe(III) sites in the Fe-RuO{sub 2} films are speculated to act as adsorption sites for the sulfur species while the Ru(IV) sites function for anodic discharge of H{sub 2}O to generate the adsorbed OH species. The investigation into cathodic H-transfer reactions, specifically nitrate reduction, at various pure metals and their alloys demonstrated that the incorporation of metals into alloy materials can create a material that exhibits bifunctional properties for the various steps involved in the overall nitrate reduction reaction. The Sb{sub 10}Sn{sub 20}Ti{sub 70}, Cu{sub 63}Ni{sub 37} and Cu{sub 25}Ni{sub 75} alloy electrodes exhibited improved activity for nitrate reduction as compared to their pure component metals. The Cu{sub 63}Ni{sub 37} alloy displayed the highest activity for nitrate reduction. The final investigation was a detailed study of the electrocatalytic activity of cathodic H-transfer reactions (nitrate reduction) at various compositions of Cu-Ni alloy electrodes. Voltammetric response for NO{sub 3}{sup -} at the Cu-Ni alloy electrode is superior to the response at the pure Cu and Ni electrodes. This is explained on the basis of the synergism of the two different metal sites at these binary alloy electrodes acting within the proposed response mechanism. Accordingly, adsorbed H-atoms are generated by cathodic discharge of H{sup +} at the Ni-sites whereas adsorption of NO{sub 3}{sup -} occurs at the Cu-sites.

Brett Kimball Simpson

2002-08-27

111

Photocatalysis of sub-ppm limonene over multiwalled carbon nanotubes/titania composite nanofiber under visible-light irradiation.  

PubMed

This study was conducted under visible-light exposure to investigate the photocatalytic characteristics of a multiwalled carbon nanotube/titania (TiO2) composite nanofiber (MTCN) using a continuous-flow tubular reactor. The MTCN was prepared by a sol-gel process, followed by an electrospinning technique. The photocatalytic decomposition efficiency for limonene on the MTCN was higher than those obtained from reference TiO2 nanofibers or P25 TiO2, and the experimental results agreed well with the Langmuir-Hinshelwood model. The CO concentrations generated during the photocatalysis did not reach levels toxic to humans. The mineralization efficiency for limonene on the MTCN was also higher than that for P25 TiO2. Moreover, the mineralization efficiency obtained using the MTCN increased steeply from 8.3 to 91.1% as the residence time increased from 7.8 to 78.0s, compared to the increase in the decomposition efficiencies for limonene from 90.1 to 99.9%. Three gas-phase intermediates (methacrolein, acetic acid, and limonene oxide) were quantitatively determined for the photocatalysis for limonene over the MTCN, whereas only two intermediates (acetic acid and limonene oxide) were quantitatively determined over P25 TiO2. Other provisional gas-phase intermediates included cyclopropyl methyl ketone and 2-ethylbutanal. PMID:25464310

Jo, Wan-Kuen; Kang, Hyun-Jung

2015-02-11

112

Mesoporous TiO2 nanocrystals grown in situ on graphene aerogels for high photocatalysis and lithium-ion batteries.  

PubMed

TiO2/graphene composites have been well studied as a solar light photocatalysts and electrode materials for lithium-ion batteries (LIBs). Recent reports have shown that ultralight 3D-graphene aerogels (GAs) can better adsorb organic pollutants and can provide multidimensional electron transport pathways, implying a significant potential application for photocatalysis and LIBs. Here, we report a simple one-step hydrothermal method toward in situ growth of ultradispersed mesoporous TiO2 nanocrystals with (001) facets on GAs. This method uses glucose as the dispersant and linker owing to its hierarchically porous structure and a high surface area. The TiO2/GAs reported here exhibit a highly recyclable photocatalytic activity for methyl orange pollutant and a high specific capacity in LIBs. The strong interaction between TiO2 and GAs, the facet characteristics, the high electrical conductivity, and the three-dimensional hierarchically porous structure of these composites results in highly active photocatalysis, a high rate capability, and stable cycling. PMID:24712676

Qiu, Bocheng; Xing, Mingyang; Zhang, Jinlong

2014-04-23

113

Influence of azo dye-TiO2 interactions on the filtration performance in a hybrid photocatalysis/ultrafiltration process.  

PubMed

Filtration performances of hollow fiber ultrafiltration membrane were investigated in a photocatalysis/ultrafiltration process used for dyeing wastewater treatment. Special attentions were focused on the dye-TiO(2) interactions and their effect on membrane flux and dye rejection. Solution pH was proved to be the predominant force that controlled the interactions by changing the surface charge characteristics of TiO(2) and altering the size and fractal dimension of TiO(2) aggregates which determined the property and structure of deposit layer. Dye-TiO(2) interaction had pronounced effect on membrane flux in adsorptive regions, but this effect became insignificant in non-adsorptive regions. The rejection of dye in the presence of TiO(2) was found to decrease markedly due to the deposition of TiO(2) particles on membrane interface. Bridging effect of TiO(2) between membrane interface and dyes produced by electronic interaction, coordination, and hydrogen bonding was responsible for the decrease in dye rejection. In view of the results presented in this paper, the interactions between pollutant and photocatalysts and their effect on the performance of membrane in hybrid photocatalysis/membrane process should be taken into consideration in the future practice. PMID:23062964

Zhang, Jiwei; Wang, Ling; Zhang, Guoliang; Wang, Zhiyang; Xu, Lusheng; Fan, Zheng

2013-01-01

114

Self-sustainable production of hydrogen, chemicals, and energy from renewable alcohols by electrocatalysis.  

PubMed

The selective and simultaneous production of hydrogen and chemicals from renewable alcohols, such as ethanol, glycerol, and ethylene glycol, can be accomplished by means of electrolyzers in which the anode electrocatalyst is appropriately designed to promote the partial and selective oxidation of the alcohol. In the electrolyzers described herein, the production of 1 kg of hydrogen from aqueous ethanol occurs with one-third the amount of energy required by a traditional H(2)/O(2) electrolyzer, by virtue of the much lower oxidation potential of ethanol to acetate vs. water to oxygen in alkaline media (E(0)=0.10 V vs. 1.23 V). The self-sustainability of H(2) production is ensured by the simultaneous production of 25 kg of potassium acetate for every kg of H(2), if the promoting co-electrolyte is KOH. PMID:20572287

Bambagioni, Valentina; Bevilacqua, Manuela; Bianchini, Claudio; Filippi, Jonathan; Lavacchi, Alessandro; Marchionni, Andrea; Vizza, Francesco; Shen, Pei Kang

2010-07-19

115

Selective Reduction of Cr(VI) in Chromium, Copper and Arsenic (CCA) Mixed Waste Streams Using UV/TiO2 Photocatalysis.  

PubMed

The highly toxic Cr(VI) is a critical component in the Chromated Copper Arsenate (CCA) formulations extensively employed as wood preservatives. Remediation of CCA mixed waste and discarded treated wood products is a significant challenge. We demonstrate that UV/TiO2 photocatalysis effectively reduces Cr(VI) to less toxic Cr(III) in the presence of arsenate, As(V), and copper, Cu(II). The rapid conversion of Cr(VI) to Cr(III) during UV/TiO2 photocatalysis occurs over a range of concentrations, solution pH and at different Cr:As:Cu ratios. The reduction follows pseudo-first order kinetics and increases with decreasing solution pH. Saturation of the reaction solution with argon during UV/TiO2 photocatalysis had no significant effect on the Cr(VI) reduction demonstrating the reduction of Cr(VI) is independent of dissolved oxygen. Reduction of Cu(II) and As(V) does not occur under the photocatalytic conditions employed herein and the presence of these two in the tertiary mixtures had a minimal effect on Cr(VI) reduction. The Cr(VI) reduction was however, significantly enhanced by the addition of formic acid, which can act as a hole scavenger and enhance the reduction processes initiated by the conduction band electron. Our results demonstrate UV/TiO2 photocatalysis effectively reduces Cr(VI) in mixed waste streams under a variety of conditions. PMID:25654531

Zheng, Shan; Jiang, Wenjun; Rashid, Mamun; Cai, Yong; Dionysiou, Dionysios D; O'Shea, Kevin E

2015-01-01

116

Study of photocatalytic degradation of tributyltin, dibutylin and monobutyltin in water and marine sediments.  

PubMed

This study reports on the first assessment of the treatment of sediments contaminated by organotin compounds using heterogeneous photocatalysis. Photocatalysis of organotins in water was carried out under realistic concentration conditions (?gL(-1)). Degradation compounds were analyzed by GC-ICP-MS; a quasi-complete degradation of tributyltin (TBT) in water (99.8%) was achieved after 30min of photocatalytic treatment. The degradation by photolysis was about (10%) in the same conditions. For the first time decontamination of highly polluted marine sediments (certified reference material and harbor sediments) by photocatalysis proves that the use of UV and the production of hydroxyl radicals are an efficient way to treat organotins adsorbed onto marine sediment despite the complexity of the matrix. In sediment, TBT degradation yield ranged from 32% to 37% after only 2h of irradiation (TiO2-UV) and the by-products: dibutyltin (DBT) and monobutyltin (MBT) were degraded very rapidly in comparison with TBT. It was shown that during photocatalysis of organotins in sediments, the hydroxyl radical attack and photolysis are the two ways for the degradation of adsorbed TBT. PMID:24613444

Brosillon, Stephan; Bancon-Montigny, Chrystelle; Mendret, Julie

2014-08-01

117

Excited state properties of diiron dithiolate hydrides: implications in the unsensitized photocatalysis of H2 evolution.  

PubMed

Density functional theory (DFT) and time-dependent DFT (TDDFT) have been used to investigate how visible light photons can excite an asymmetrically substituted diiron hydride, [Fe2(pdt)(?-H)(CO)4dppv](+) (1(+), dppv = cis-1,2-C2H2(PPh2)2; pdt = 1,3-propanedithiolate), as well as the symmetric species [Fe2(pdt)(?-H)(CO)4(PMe3)2](+) (2(+)), which are the first photocatalysts of proton reduction operating without employing sensitizers (Wang, W.; Rauchfuss, T. B.; Bertini, L.; Zampella, G.; J. Am. Chem. Soc., 2012, 134, 4525). Theoretical results illustrate that the peculiar reactivity associated to the excited states of 1(+) and 2(+) is compatible with three different scenarios: (i) it can arise from the movement of the hydride ligand from fully bridging to semibridging/terminal coordination, which is expected to be more reactive toward protons; (ii) reactivity could be related to cleavage of a Fe-S bond, which implies formation of a transient Fe penta-coordinate species that would trigger a facile turnstile hydride isomerization, if lifetime excitation is long enough; (iii) also in line with a Fe-S bond cleavage is the possibility that after excited state decay, a highly basic S center is protonated so that a species simultaneously containing S-H(?+) and Fe-H(?-) moieties is formed and, once reduced by a suitable electron donor, it can readily afford H2 plus an unprotonated form of the FeFe complex. This last possibility is consistent with (31)P NMR and IR solution data. All the three possibilities are compatible with the capability of 1(+) and 2(+) to perform photocatalysis of hydrogen evolving reaction (HER) without sensitizer. Moreover, even though it turned out difficult to discriminate among the three scenarios, especially because of the lack of experimental excitation lifetimes, it is worth underscoring that all of the three pathways represent a novelty regarding diiron carbonyl photoreactivity, which is usually associated with CO loss. Results provide also a rationale to the experimental observations which showed that the simultaneous presence of donor ligands (dppv in the case of 1(+)) and a H ligand in the coordination environment of diiron complexes is a key factor to prevent CO photodissociation and catalyze HER. Finally, the comparison of photoexcitation behavior of 1(+) and 2(+) allows a sort of generalization about the functioning of such hydride species. PMID:23952259

Bertini, Luca; Fantucci, Piercarlo; De Gioia, Luca; Zampella, Giuseppe

2013-09-01

118

Facile one-pot synthesis of flower-like AgCl microstructures and enhancing of visible light photocatalysis  

PubMed Central

Flower-like AgCl microstructures with enhanced visible light-driven photocatalysis are synthesized by a facile one-pot hydrothermal process for the first time. The evolution process of AgCl from dendritic structures to flower-like octagonal microstructures is investigated quantitatively. Furthermore, the flower-like AgCl microstructures exhibit enhanced ability of visible light-assisted photocatalytic degradation of methyl orange. The enhanced photocatalytic activity of the flower-like AgCl microstructure is attributed to its three-dimensional hierarchical structure exposing with [100] facets. This work provides a fresh view into the insight of electrochemical process and the application area of visible light photocatalysts. PMID:24153176

2013-01-01

119

Plant Uptake-Assisted Round-the-Clock Photocatalysis for Complete Purification of Aquaculture Wastewater Using Sunlight.  

PubMed

A novel reactor equipped with solar batteries, Bi2O3/TiO2 film photocatalyst, and celery plant was designed and used for purification of aquaculture wastewater. The Bi2O3/TiO2 film photocatalyst started photocatalytic degradation of organonitrogen compounds under irradiation of sunlight. Meanwhile, the solar batteries absorbed and converted excess sunlight into electric energy and then started UV lamps at night, leading to round-the-clock photocatalysis. Subsequently, the inorganic nitrogen species including NH4(+), NO2(-), and NO3(-) resulting from photocatalytic degradation of the organonitrogen compounds could subsequently be uptaken by the celery plant as the fertilizer to reduce the secondary pollution. It was found that, after 24 h circulation, both organonitrogen compounds and NO2(-) species were completely removed, while NH4(+) and NO3(-) contents also decreased by 30% and 50%, respectively. The reactor could be used repetitively, showing a good potential in practical application. PMID:25625860

Bian, Zhenfeng; Cao, Fenglei; Zhu, Jian; Li, Hexing

2015-02-17

120

Solar photocatalytic degradation of some hazardous water-soluble pesticides at pilot-plant scale.  

PubMed

The technical feasibility and performance of photocatalytic degradation of six water-soluble pesticides (cymoxanil, methomyl, oxamyl, dimethoate, pyrimethanil and telone) have been studied at pilot-plant scale in two well-defined systems which are of special interest because natural solar UV light can be used: heterogeneous photocatalysis with titanium dioxide and homogeneous photocatalysis by photo-Fenton. TiO(2) photocatalysis tests were performed in a 35L solar pilot plant with three Compound Parabolic Collectors (CPCs) under natural illumination and a 75L solar pilot plant with four CPC units was used for homogeneous photocatalysis tests. The initial pesticide concentration studied was 50 mg L(-1) and the catalyst concentrations employed were 200 mg L(-1) of TiO(2) and 20 mg L(-1) of iron. Both toxicity (Vibrio fischeri, Biofix) and biodegradability (Zahn-Wellens test) of the initial pesticide solutions were also measured. Total disappearance of the parent compounds and nearly complete mineralization were attained with all pesticides tested. Treatment time, hydrogen peroxide consumption and release of heteroatoms are discussed. PMID:16839679

Oller, I; Gernjak, W; Maldonado, M I; Pérez-Estrada, L A; Sánchez-Pérez, J A; Malato, S

2006-12-01

121

TiO2 sol-gel for formaldehyde photodegradation using polymeric support: photocatalysis efficiency versus material stability.  

PubMed

Photocatalysts supported on polymers are not frequently used in heterogeneous photocatalysis because of problems such as wettability and stability that affect photocatalysis conditions. In this work, we used polypropylene as support for TiO2 sol-gel to evaluate its stability and efficiency under UV radiation. We also tested the effect of the thermo-pressing PP/TiO2 system on the photocatalytic efficiency and stability under UV radiation. The films were characterized by scanning electron microscopy (SEM), UV-Vis spectroscopy and X-ray diffraction (XRD). The SEM micrographs showed that the films of TiO2 sol-gel onto PP has approximately 1.0-?m thick and regular surface and the generation of polypropylene nanowires on hot-pressed samples. XRD showed the formation of TiO2 anatase on the surface of the films made by dip-coating. All photocatalysts were tested in decontaminating air-containing gaseous formaldehyde (70 ppmv) presenting degradation of the target compound to the limit of detection. The photocatalysts showed no deactivation during the entire period tested (30 h), and its reuse after washing showed better photocatalytic performance than on first use. The photocatalyst showed the best results were tested for 360 h with no observed deactivation. Aging studies showed that the film of TiO2 causes different effects on the photostability of composites, with stabilizing effect when exposed to most energetic UVC radiation (?max?=?254 nm) and degradative effects when exposed to UVA radiation (?max?=?365 nm). PMID:24604273

Curcio, Monique S; Oliveira, Michel P; Waldman, Walter R; Sánchez, Benigno; Canela, Maria Cristina

2015-01-01

122

Computational Catalysis and Electrocatalysis  

E-print Network

;Tools-hardware Novel catalytic designs require reaching the atomistic world How? Solving exact laws that certain layered materials have good storage capacity at moderate pressures and room temperature Lamonte catalysts for this important reaction Photo-catalytic process #12;Acknowledgements Department of Energy

123

Water  

MedlinePLUS

... the 1986 and 1996 amendments to the Safe Drinking Water Act ( http://www.epa.gov/safewater/sdwa/index. ... You cannot see, taste, or smell lead in drinking water. Therefore, you must ask your water provider whether ...

124

Water  

MedlinePLUS

... to groundwater (the fresh water found under the Earth’s surface that supplies wells and springs). Everything that ... body is water. 4. How much of the earth’s surface is water? About 80 percent of the ...

125

An unexplored O2-involved pathway for the decarboxylation of saturated carboxylic acids by TiO2 photocatalysis: an isotopic probe study.  

PubMed

The aerobic decarboxylation of saturated carboxylic acids (from C(2) to C(5)) in water by TiO(2) photocatalysis was systematically investigated in this work. It was found that the split of C(1)-C(2) bond of the acids to release CO(2) proceeds sequentially (that is, a C(5) acid sequentially forms C(4) products, then C(3) and so forth). As a model reaction, the decarboxylation of propionic acid to produce acetic acid was tracked by using isotopic-labeled H(2)(18)O. As much as ?42% of oxygen atoms of the produced acetic acids were from dioxygen ((16)O(2)). Through diffuse reflectance FTIR measurements (DRIFTS), we confirmed that an intermediate pyruvic acid was generated prior to the cut-off of the initial carboxyl group; this intermediate was evidenced by the appearance of an absorption peak at 1772 cm(-1) (attributed to C=O stretch of ?-keto group of pyruvic acid) and the shift of this peak to 1726 cm(-1) when H(2)(16)O was replaced by H(2)(18)O. Consequently, pyruvic acid was chosen as another model molecule to observe how its decarboxylation occurs in H(2)(16)O under an atmosphere of (18)O(2). With the ?-keto oxygen of pyruvic acid preserved in the carboxyl group of acetic acid, ?24% new oxygen atoms of the produced acetic acid were from molecular oxygen at near 100% conversion of pyruvic acid. The other ?76% oxygen atoms were provided by H(2)O through hole/OH radical oxidation. In the presence of conduction band electrons, O(2) can independently accomplish such C(1)-C(2) bond cleavage of pyruvic acid to generate acetic acid with ?100% selectivity, as confirmed by an electrochemical experiment carried out in the dark. More importantly, the ratio of O(2) participation in decarboxylation increased along with the increase of pyruvic acid conversion, indicating the differences between non-substituted acids and ?-keto acids. This also suggests that the O(2)-dependent decarboxylation competes with hole/OH-radical-promoted decarboxylation and depends on TiO(2) surface defects at which Ti(4c) sites are available for the simultaneous coordination of substrates and O(2). PMID:20857460

Wen, Bo; Li, Yue; Chen, Chuncheng; Ma, Wanhong; Zhao, Jincai

2010-10-18

126

DOE Laboratory Catalysis Research Symposium - Abstracts  

SciTech Connect

The conference consisted of two sessions with the following subtopics: (1) Heterogeneous Session: Novel Catalytic Materials; Photocatalysis; Novel Processing Conditions; Metals and Sulfides; Nuclear Magnetic Resonance; Metal Oxides and Partial Oxidation; Electrocatalysis; and Automotive Catalysis. (2) Homogeneous Catalysis: H-Transfer and Alkane Functionalization; Biocatalysis; Oxidation and Photocatalysis; and Novel Medical, Methods, and Catalyzed Reactions.

Dunham, T.

1999-02-01

127

Bifunctional AgCl/Ag composites for SERS monitoring and low temperature visible light photocatalysis degradation of pollutant  

NASA Astrophysics Data System (ADS)

With the assistance of Polyvinylpyrrolidone (PVP), AgCl/Ag composites were fabricated in N, N-Dimethylformamide (DMF) solvent via a photoactivated route. The size of AgCl particles was in the range of 500 nm to 1 ?m and the Ag particle's diameter was about 10-20 nm. Different from those core-shell structures reported before, the Ag nanoparticles were dispersed uniformly both on the surface and in the body of AgCl particles. The generation of such kind of composites was resulted from the reducing ability of DMF and light irradiation during the formation of AgCl particles. The as-obtained AgCl/Ag composites presented great activity for both surface-enhanced Raman scattering (SERS) detection and visible light photocatalytic degradation of organic dyes. Additionally, the AgCl/Ag composites could maintain high photocatalytic activity even though the ambient temperature was as low as 15 °C and recycle photocatalysis experiments indicated that the photocatalyst exhibited higher stability. Such kind of AgCl/Ag composites holds great potential for environmental monitoring devices and pollutant treatments.

Dong, Lihong; Zhu, Junyi; Xia, Guangqing

2014-12-01

128

The highly efficient photocatalysts of Co/TiO2: Photogenerated charge-transfer properties and their applications in photocatalysis  

NASA Astrophysics Data System (ADS)

A convenient and simple sol-gel method has been developed for the synthesis of anatase TiO2 and Co-doped TiO2 nanoparticles. The samples were characterized by XRD, XPS, UV-vis DRS and it was found that the dopant ions replaced some of the crystal lattice titanium ions, existing in the form of Co2+. UV-vis DRS confirm that the obtained Co/TiO2 samples have an extended light absorption range compared with pure TiO2. Photocatalytic activities of the catalysts were assessed based on the degradation of single rhodamine B (RhB) and mixed dyes in aqueous solution in the present of visible light (? > 420 nm). With an optimal molar ratio of 1% (Co/Ti), the sample shows the highest rate photodegradation efficiency under the same experimental conditions. SPV was used to investigate photophysical mechanism of the visible light photocatalytic activity and revealed that there is an electronic interaction between the Co and TiO2, which plays a significant effect in improving the efficiency of photocatalysis.

Yue, Xinzheng; Jiang, Shang; Ni, Ling; Wang, Runwei; Qiu, Shilun; Zhang, Zongtao

2014-11-01

129

Control of gas-phase chlorobenzene using TiO{sub 2}-mediated photocatalysis and packed-bed absorption  

SciTech Connect

Gas-phase chlorobenzene degradation using combined TiO{sub 2}-mediated photocatalysis and packed-bed absorption was investigated with a bench-scale three-phase photocatalytic/absorption apparatus. Both physical and chemical techniques were used to prepare silica-supported, platinized catalyst. The two silica-supported photocatalysts showed faster degradation rates for the chlorobenzene than a simple slurry platinized titania. The chemical method was found to be more abrasion resistant and produce chlorobenzene degradations around 50%, with 37% mineralization to CO{sub 2}. Operation with the absorption column did not increase steady-state chlorobenzene degradation rates appreciably over that of the system without the absorption column. A reactor model was developed using first-order degradation kinetics. Based on the results, the apparent mass-transfer coefficient of absorption and degradation were determined. When inlet loading increased, the absorption and degradation coefficient increased. A linear correlation was found between the inlet loading and the absorption and degradation coefficients.

Martin, R.S.; Richardson, C.P.; Fan, T.; Halbert, C.P. IV [New Mexico Tech, Socorro, NM (United States)

1998-12-31

130

Visible Light Photocatalysis with Nitrogen-Doped Titanium Dioxide Nanoparticles Prepared by Plasma Assisted Chemical Vapor Deposition  

SciTech Connect

Nitrogen-doped TiO{sub 2} nanoparticles were synthesized via plasma assisted metal organic chemical vapor deposition. Nitrogen dopant concentration was varied from 0 to 1.61 at. %. The effect of nitrogen ion doping on visible light photocatalysis has been investigated. Samples were analyzed by various analytical techniques such as x-ray diffraction, transmission electron microscopy, x-ray photoelectron spectroscopy, and near-edge x-ray absorption fine structure. Titanium tetraisopropoxide was used as the titanium precursor, while rf-plasma-decomposed ammonia was used as the source for nitrogen doping. The N-doped TiO{sub 2} nanoparticles were deposited on stainless steel mesh under a flow of Ar and O2 gases at 600 {sup o}C in a tube reactor. The photocatalytic activity of the prepared N-doped TiO{sub 2} samples was tested by the degradation of 2-chlorophenol (2-CP) in an aqueous solution using a visible lamp equipped with an UV filter. The efficiency of photocatalytic oxidation of 2-CP was measured using high performance liquid chromatography. Results obtained revealed the formation of N-doped TiO{sub 2} samples as TiO{sub 2-x}N{sub x}, and a corresponding increase in the visible light photocatalytic activity.

Buzby,S.; Barakat, M.; Lin, H.; Ni, C.; Rykov, S.; Chen, J.; Shah, S.

2006-01-01

131

Photocatalysis-triggered ion rectification in artificial nanochannels based on chemically modified asymmetric TiO2 nanotubes.  

PubMed

Ion rectification is one of the important characteristics of biological ion channels. Inspired by the function of biological ion channels, creation of artificial nanochannels that show analogous ion rectification characteristics has attracted a great interest recently. Herein, we demonstrate a new type of artificial solid-state nanochannel with ion rectification characteristics. The creation of artificial nanochannels includes the formation of asymmetric TiO2 nanotubes by electrochemical anodization of Ti metal, followed by chemical modification with octadecyltrimethoxysilane (OTS) molecules. The carboxylic groups are introduced onto the tip side of TiO2 nanotubes via photocatalytic decomposition of OTS molecules by TiO2 photocatalysis under ultraviolet light. When the radius of tip side of TiO2 nanotubular channels is comparable to the thickness of electric double layer, the negatively charged surface in neutral electrolyte in combination with the asymmetric pore geometry contributes to the ion rectification characteristics. Compared with previous artificial nanochannels, our new type of artificial nanochannel is more facile to fabricate and behaves as a diode that rectifies the ion transport, which also shows some other potential applications, such as sensor and separation materials. PMID:23517411

Hu, Ziying; Zhang, Qianqian; Gao, Jun; Liu, Zhaoyue; Zhai, Jin; Jiang, Lei

2013-04-16

132

Fabrication of Au/Graphene-Wrapped ZnO-Nanoparticle-Assembled Hollow Spheres with Effective Photoinduced Charge Transfer for Photocatalysis.  

PubMed

Heterostructures of gold-nanoparticle-decorated reduced-graphene-oxide (rGO)-wrapped ZnO hollow spheres (Au/rGO/ZnO) are synthesized using tetra-n-butylammonium bromide as a mediating agent. The structure of amorphous ZnO hollow spheres is found to be transformed from nanosheet- to nanoparticle-assembled hollow spheres (nPAHS) upon annealing at 500 °C. The ZnO nPAHS hybrids with Au/rGO are characterized using various techniques, including photoluminescence, steady-state absorbance, time-resolved photoluminescence, and photocatalysis. The charge-transfer time of ZnO nPAHS is found to be 87 ps, which is much shorter than that of a nanorod (128 ps), nanoparticle (150 ps), and nanowall (990 ps) due to its unique structure. The Au/rGO/ZnO hybrid shows a higher charge-transfer efficiency of 68.0% in comparison with rGO/ZnO (40.3%) and previously reported ZnO hybrids. The photocatalytic activities of the samples are evaluated by photodegrading methylene blue under black-light irradiation. The Au/rGO/ZnO exhibits excellent photocatalytic efficiency due to reduced electron-hole recombination, fast electron-transfer rate, and high charge-transfer efficiency. PMID:25629618

Khoa, Nguyen Tri; Kim, Soon Wook; Yoo, Dae-Hwang; Cho, Shinuk; Kim, Eui Jung; Hahn, Sung Hong

2015-02-18

133

A new dielectric ta-C film coating of Ag-nanoparticle hybrids to enhance TiO2 photocatalysis  

NASA Astrophysics Data System (ADS)

We have demonstrated a novel method to enhance TiO2 photocatalysis by adopting a new ultrathin tetrahedral-amorphous-carbon (ta-C) film coating on Ag nanoparticles to create strong plasmonic near-field enhancement. The result shows that the decomposition rate of methylene blue on the Ag/10 Å ta-C/TiO2 composite photocatalyst is ten times faster than that on a TiO2 photocatalyst and three times faster than that on a Ag/TiO2 photocatalyst. This can be ascribed to the simultaneous realization of two competitive processes: one that excites the surface plasmons (SPs) of the ta-C-film/Ag-nanoparticle hybrid and provides a higher electric field near the ta-C/TiO2 interface compared to Ag nanoparticles alone, while the other takes advantage of the dense diamond-like ta-C layer to help reduce the transfer of photogenerated electrons from the conduction band of TiO2 to the metallic surface, since any electron transfer will suppress the excitation of SP modes in the metal nanoparticles.

Liu, Fanxin; Tang, Chaojun; Wang, Zhenlin; Sui, Chenghua; Ma, Hongtao

2014-03-01

134

NASA's Potential Contributions for Remediation of Retention Ponds Using Solar Ultraviolet Radiation and Photocatalysis  

NASA Technical Reports Server (NTRS)

This Candidate Solution uses NASA Earth science research on atmospheric ozone and aerosols data (1) to help improve the prediction capabilities of water runoff models that are used to estimate runoff pollution from retention ponds, and (2) to understand the pollutant removal contribution and potential of photocatalytically coated materials that could be used in these ponds. Models (the EPA's SWMM and the USGS SLAMM) exist that estimate the release of pollutants into the environment from storm-water-related retention pond runoff. UV irradiance data acquired from the satellite mission Aura and from the OMI Surface UV algorithm will be incorporated into these models to enhance their capabilities, not only by increasing the general understanding of retention pond function (both the efficacy and efficiency) but additionally by adding photocatalytic materials to these retention ponds, augmenting their performance. State and local officials who run pollution protection programs could then develop and implement photocatalytic technologies for water pollution control in retention ponds and use them in conjunction with existing runoff models. More effective decisions about water pollution protection programs could be made, the persistence and toxicity of waste generated could be minimized, and subsequently our natural water resources would be improved. This Candidate Solution is in alignment with the Water Management and Public Health National Applications.

Underwood, Lauren W.; Ryan, Robert E.

2007-01-01

135

Water  

NSDL National Science Digital Library

This tutorial examines the importance of water to Earth's ecosystems. Topics include the sources and distribution of water, the water cycle, and how snow and rain occur. There is a discussion of the phases in which it can exist (solid, liquid, or vapor), and a description of how animals adapt to cold snowy environments in the winter. Examples include burrowing, hibernation, migration, and thick fur. A quiz and glossary are included.

136

Water  

NSDL National Science Digital Library

This video segment from IdahoPTV's D4K shows us from where we get water, how it's stored and how powerful it can be. We learn how important it is to conserve the .3% of usable fresh water available on earth.

Idaho PTV

2011-10-06

137

Water  

NSDL National Science Digital Library

The same water that has existed on Earth for millions of years travels through a series of steps in a cycle from mountains to the sea, flows in and out of the cells in your body, and comprises 95% of the mass of a jellyfish. In short, water is the connect

Frederick, J. A.; Blake Jr., Robert W.; Haines, Sarah; Lee, Stephanie C.

2010-02-01

138

C60 aminofullerene-magnetite nanocomposite designed for efficient visible light photocatalysis  

E-print Network

recyclable photosensitizing system for harnessing solar energy for water treatment and disinfection been attracting attention in the development of solar-powered systems for environmental remediation is reported. This system comprises C60 aminofullerene as a sen- sitizer for singlet oxygenation

Alvarez, Pedro J.

139

Direct electrochemistry and electrocatalysis of heme proteins immobilised in carbon-coated nickel magnetic nanoparticle-chitosan-dimethylformamide composite films in room-temperature ionic liquids.  

PubMed

The direct electrochemistry and electrocatalysis of heme proteins entrapped in carbon-coated nickel magnetic nanoparticle-chitosan-dimethylformamide (CNN-CS-DMF) composite films were investigated in the hydrophilic ionic liquid [bmim][BF4]. The surface morphologies of a representative set of films were characterised via scanning electron microscopy. The proteins immobilised in the composite films were shown to retain their native secondary structure using UV-vis spectroscopy. The electrochemical performance of the heme proteins-CNN-CS-DMF films was evaluated via cyclic voltammetry and chronoamperometry. A pair of stable and well-defined redox peaks was observed for the heme protein films at formal potentials of -0.151 V (HRP), -0.167 V (Hb), -0.155 V (Mb) and -0.193 V (Cyt c) in [bmim][BF4]. Moreover, several electrochemical parameters of the heme proteins were calculated by nonlinear regression analysis of the square-wave voltammetry. The addition of CNN significantly enhanced not only the electron transfer of the heme proteins but also their electrocatalytic activity toward the reduction of H2O2. Low apparent Michaelis-Menten constants were obtained for the heme protein-CNN-CS-DMF films, demonstrating that the biosensors have a high affinity for H2O2. In addition, the resulting electrodes displayed a low detection limit and improved sensitivity for detecting H2O2, which indicates that the biocomposite film can serve as a platform for constructing new non-aqueous biosensors for real detection. PMID:23632434

Wang, Ting; Wang, Lu; Tu, Jiaojiao; Xiong, Huayu; Wang, Shengfu

2013-12-01

140

Combination of photocatalysis and HC/SCR for improved activity and durability of DeNOx catalysts.  

PubMed

A photocatalytic HC/SCR system has been developed and its high deNOx performance (54.0-98.6% NOx conversion) at low temperatures (150-250 °C) demonstrated by using a representative diesel fuel hydrocarbon (dodecane) as the reductant over a hybrid SCR system of a photocatalytic reactor (PCR) and a dual-bed HC/SCR reactor. The PCR generates highly active oxidants such as O3 and NO2 from O2 and NO in the feed stream, followed by the subsequent formation of highly efficient reductants such as oxygenated hydrocarbon (OHC), NH3, and organo-nitrogen compounds. These reductants are the key components for enhancing the low temperature deNOx performance of the dual-bed HC/SCR system containing Ag/Al2O3 and CuCoY in the front and rear bed of the reactor, respectively. The OHCs are particularly effective for both NOx reduction and NH3 formation over the Ag/Al2O3 catalyst, while NH3 and organo-nitrogen compounds are effective for NOx reduction over the CuCoY catalyst. The hybrid HC/SCR system assisted by photocatalysis has shown an overall deNOx performance comparable to that of the NH3/SCR, demonstrating its potential as a promising alternative to the current urea/SCR and LNT technologies. Superior durability of HC/SCR catalysts against coking by HCs has also been demonstrated by a PCR-assisted regeneration scheme for deactivating catalysts. PMID:23586945

Heo, Iljeong; Kim, Mun Kyu; Sung, Samkyung; Nam, In-Sik; Cho, Byong K; Olson, Keith L; Li, Wei

2013-04-16

141

Photochemical preparation of CdS hollow microspheres at room temperature and their use in visible-light photocatalysis  

SciTech Connect

CdS hollow microspheres have been successfully prepared by a photochemical preparation technology at room temperature, using polystyrene latex particles as templates, CdSO{sub 4} as cadmium source and Na{sub 2}S{sub 2}O{sub 3} as both sulphur source and photo-initiator. The process involved the deposition of CdS nanoparticles on the surface of polystyrene latex particles under the irradiation of an 8 W UV lamp and the subsequent removal of the latex particles by dispersing in dichloromethane. Photochemical reactions at the sphere/solution interface should be responsible for the formation of hollow spheres. The as-prepared products were characterized by X-ray diffraction, transmission electron microscopy and scanning electron microscopy. Such hollow spheres could be used in photocatalysis and showed high photocatalytic activities in photodegradation of methyl blue (MB) in the presence of H{sub 2}O{sub 2}. The method is green, simple, universal and can be extended to prepare other sulphide and oxide hollow spheres. -- Graphical abstract: Taking polystyrene spheres dispersed in a precursor solution as templates, CdS hollow microspheres composed of nanoparticles were successfully prepared via a new photochemical route at room temperature. Display Omitted Research highlights: {yields} Photochemical method was first employed to prepare hollow microspheres. {yields} CdS hollow spheres were first prepared at room temperature using latex spheres. {yields} The polystyrene spheres used as templates were not modified with special groups. {yields}The CdS hollow microspheres showed high visible-light photocatalytic activities.

Huang Yuying [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Sun Fengqiang, E-mail: fengqiangsun@yahoo.c [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Key Laboratory of Electrochemical Technology on Energy Storage and Power Generation in GuangDong Universities, Guangzhou 510006 (China); Engineering Research Center of Materials and Technology for Electrochemical Energy Storage (Ministry of Education), South China Normal University, Guangzhou 510006 (China); Wu Tianxing; Wu Qingsong; Huang Zhong; Su Heng; Zhang Zihe [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China)

2011-03-15

142

Photocatalysis on (CdS) x (ZnTe)1 - x solid solutions  

NASA Astrophysics Data System (ADS)

Photocatalytic properties of the surface of binary compounds (CdS, ZnTe) and solid solutions (CdS) x (ZnTe)1 - x formed on their basis are studied by means of potentiometry and chromatography. The values of forbidden gap ? E are calculated from the resulting UV spectra, according to which the components of the CdS-ZnTe system can display photocatalytic activity in the wavelength range of 364 to 670 nm. A scheme of a model setup for producing hydrogen from water is proposed using the authors' method.

Karpova, E. O.; Nagibina, I. Yu.; Makarova, A. S.

2015-01-01

143

On the role of localized surface plasmon resonance in UV-Vis light irradiated Au/TiO2 photocatalysis systems: pros and cons.  

PubMed

The role of localized surface plasmon resonance (LSPR) in UV-Vis light irradiated Au/TiO2 photocatalysis systems has been investigated, and it is demonstrated experimentally for the first time that both pros and cons of LSPR exist simultaneously for this photocatalytic reaction. We have proved that when operating under mixed UV and green light irradiation, the LSPR injected hot electrons (from the Au nanoparticles to TiO2 under green light irradiation) may surmount the Schottky barrier (SB) formed between the Au nanoparticles and TiO2, and flow back into the TiO2. As a result, these electrons may compensate for and even surpass those transferred from TiO2 to the Au nanoparticles, thus accelerating the recombination of UV excited electron-hole pairs in TiO2. This is the negative effect of LSPR. On the other hand, more hot electrons existing on the surface of the Au nanoparticles due to LSPR would favor the photocatalytic reaction, which accompanied by the negative effect dominates the overall photocatalytic performance. The presented results reveal the multi-faceted essence of LSPR in Au/TiO2 structures, and is instructive for the application of metal-semiconductor composites in photocatalysis. Moreover, it is confirmed that the extent to which the above pros and cons of LSPR dominate the overall photocatalytic reaction depends on the intensity ratio of visible to UV light. PMID:25665512

Lin, Zhongjin; Wang, Xiaohong; Liu, Jun; Tian, Zunyi; Dai, Loucheng; He, Beibei; Han, Chao; Wu, Yigui; Zeng, Zhigang; Hu, Zhiyu

2015-02-19

144

Simultaneous monitoring of photocatalysis of three pharmaceuticals by immobilized TiO2 nanoparticles: Chemometric assessment, intermediates identification and ecotoxicological evaluation  

NASA Astrophysics Data System (ADS)

In this study, the photocatalytic degradation of a mixture of three pharmaceuticals, Metronidazole (MET), Atenolol (ATL) and Chlorpromazine (CPR), was quantified simultaneously during the UV/TiO2 process. The investigated TiO2 was Millennium PC-500 immobilized on ceramic plates by sol-gel based method. The partial least squares modeling was successfully applied for the multivariate calibration of the spectrophotometric data. The central composite design was applied to model and optimize the UV/TiO2 process. Predicted values of removal efficiency were found to be in good agreement with experimental values for MET, ATL and CPR (R2 = 0.947 and Adj-R2 = 0.906, R2 = 0.977 and Adj-R2 = 0.960 and R2 = 0.982 and Adj-R2 = 0.969, respectively). The optimum initial concentration of pharmaceuticals, reaction time and UV light intensity was found to be 10 mg L-1, 150 min and 38.45 W m-2, respectively. The main degradation intermediates of pharmaceuticals produced in this process were identified by GC-MS technique. The chronic ecotoxicity of pharmaceuticals was evaluated using aquatic species Spirodela polyrrhiza prior to and after photocatalysis. The TOC results (90% removal after 16 h) and ecotoxicological experiments revealed that the photocatalysis process could effectively mineralize and reduce the ecotoxicity of the pharmaceuticals from their aqueous solutions.

Khataee, A. R.; Fathinia, M.; Joo, S. W.

2013-08-01

145

Band-engineered SrTiO{sub 3} nanowires for visible light photocatalysis  

SciTech Connect

We have theoretically investigated the structural, electronic, and optical properties of perovskite SrTiO{sub 3} nanowires for use in visible light photocatalytic applications using pseudopotential density-functional theory calculations. The electronic structure calculations show that the band gap is modified in the SrTiO{sub 3} nanowires compared with that of the bulk. For TiO{sub 2}-terminated nanowires, the mid-band states induced by the combination of oxygen and strontium atoms on the surface lead to a shift in the valence band toward the conduction band without interference from the edge of the conduction band, which reduces the band gap. On the contrary, the electronic states induced by the combination of oxygen and strontium atoms on the surface of SrO-terminated nanowires lead to a shift in the conduction band toward the valence band. The calculated optical results indicate that the absorption edge of the nanowires shift towards the red-light region. These theoretical results suggest that perovskite SrTiO{sub 3} nanowires are promising candidates for use in visible light photocatalytic processes such as solar-assisted water splitting reactions.

Fu, Q.; He, T.; Li, J. L.; Yang, G. W. [State Key Laboratory of Optoelectronic Materials and Technologies, Institute of Optoelectronic and Functional Composite Materials, Nanotechnology Research Center, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275, Guangdong (China)

2012-11-15

146

Water  

Microsoft Academic Search

Water is an essential nutrient required for life. To be well hydrated, the average sedentary adult man must consume at least 2,900 mL (12 c) fluid per day, and the average sedentary adult woman at least 2,200 mL (9 c) fluid per day, in the form of noncaffeinated, nonalcoholic beverages, soups, and foods. Solid foods contribute approximately 1,000 mL (4

SUSAN M KLEINER

1999-01-01

147

Electrochemical surface science twenty years later: Expeditions into the electrocatalysis of reactions at the core of artificial photosynthesis  

NASA Astrophysics Data System (ADS)

Surface science research fixated on phenomena and processes that transpire at the electrode-electrolyte interface has been pursued in the past. A considerable proportion of the earlier work was on materials and reactions pertinent to the operation of small-molecule fuel cells. The experimental approach integrated a handful of surface-sensitive physical-analytical methods with traditional electrochemical techniques, all harbored in a single environment-controlled electrochemistry-surface science apparatus (EC-SSA); the catalyst samples were typically precious noble metals constituted of well-defined single-crystal surfaces. More recently, attention has been diverted from fuel-to-energy generation to its converse, (solar) energy-to-fuel transformation; e.g., instead of water synthesis (from hydrogen and oxygen) in fuel cells, water decomposition (to hydrogen and oxygen) in artificial photosynthesis. The rigorous surface-science protocols remain unchanged but the experimental capabilities have been expanded by the addition of several characterization techniques, either as EC-SSA components or as stand-alone instruments. The present manuscript describes results selected from on-going studies of earth-abundant electrocatalysts for the reactions that underpin artificial photosynthesis: nickel-molybdenum alloys for the hydrogen evolution reaction, calcium birnessite as a heterogeneous analogue for the oxygen-evolving complex in natural photosynthesis, and single-crystalline copper in relation to the carbon dioxide reduction reaction.

Soriaga, Manuel P.; Baricuatro, Jack H.; Cummins, Kyle D.; Kim, Youn-Geun; Saadi, Fadl H.; Sun, Guofeng; McCrory, Charles C. L.; McKone, James R.; Velazquez, Jesus M.; Ferrer, Ivonne M.; Carim, Azhar I.; Javier, Alnald; Chmielowiec, Brian; Lacy, David C.; Gregoire, John M.; Sanabria-Chinchilla, Jean; Amashukeli, Xenia; Royea, William J.; Brunschwig, Bruce S.; Hemminger, John C.; Lewis, Nathan S.; Stickney, John L.

2015-01-01

148

Reactions of oxygen-containing molecules on transition metal carbides: Surface science insight into potential applications in catalysis and electrocatalysis  

NASA Astrophysics Data System (ADS)

Historically the interest in the catalytic properties of transition metal carbides (TMC) has been inspired by their "Pt-like" properties in the transformation reactions of hydrocarbon molecules. Recent studies, however, have revealed that the reaction pathways of oxygen-containing molecules are significantly different between TMCs and Pt-group metals. Nonetheless, TMCs demonstrate intriguing catalytic properties toward oxygen-containing molecules, either as the catalyst or as the catalytically active substrate to support metal catalysts, in several important catalytic and electrocatalytic applications, including water electrolysis, alcohol electrooxidation, biomass conversion, and water gas shift reactions. In the current review we provide a summary of theoretical and experimental studies of the interaction of TMC surfaces with oxygen-containing molecules, including both inorganic (O2, H2O, CO and CO2) and organic (alcohols, aldehydes, acids and esters) molecules. We will discuss the general trends in the reaction pathways, as well as future research opportunities in surface science studies that would facilitate the utilization of TMCs as catalysts and electrocatalysts.

Stottlemyer, Alan L.; Kelly, Thomas G.; Meng, Qinghe; Chen, Jingguang G.

2012-09-01

149

Reactions of oxygen-containing molecules on transition metal carbides: Surface science insight into potential applications in catalysis and electrocatalysis  

NASA Astrophysics Data System (ADS)

Historically the interest in the catalytic properties of transition metal carbides (TMC) has been inspired by their “Pt-like” properties in the transformation reactions of hydrocarbon molecules. Recent studies, however, have revealed that the reaction pathways of oxygen-containing molecules are significantly different between TMCs and Pt-group metals. Nonetheless, TMCs demonstrate intriguing catalytic properties toward oxygen-containing molecules, either as the catalyst or as the catalytically active substrate to support metal catalysts, in several important catalytic and electrocatalytic applications, including water electrolysis, alcohol electrooxidation, biomass conversion, and water gas shift reactions. In the current review we provide a summary of theoretical and experimental studies of the interaction of TMC surfaces with oxygen-containing molecules, including both inorganic (O2, H2O, CO and CO2) and organic (alcohols, aldehydes, acids and esters) molecules. We will discuss the general trends in the reaction pathways, as well as future research opportunities in surface science studies that would facilitate the utilization of TMCs as catalysts and electrocatalysts.

Stottlemyer, Alan L.; Kelly, Thomas G.; Meng, Qinghe; Chen, Jingguang G.

2012-09-01

150

Energy transduction inside vesicles, photocatalysis by titanium dioxide and formation of NADH  

NASA Astrophysics Data System (ADS)

A number of theories on the origin and early evolution of life have focused on the role of lipid bilayer membrane structures (vesicles). These vesicles are similar to modern cellular membranes , and have been postulated to have been abiotically formed and spontaneously assemble on the prebiotic Earth to provide compartments for early cellular life. They can contain water-soluble species, concentrate species, and have the potential to catalyze reactions. The origin of the use of photochemical energy to drive metabolism (ie. energy transduction) is also one of the central issues in our attempts to understand the origin and evolution of life. When did energy transduction and photosynthesis begin? What was the original system for capturing photochemical energy? How simple can such a system be? It has been postulated that vesicle structures developed the ability to capture and transduce light, providing energy for reactions. It has been shown that pH gradients can be photo-chemically created, but it has been found difficult to couple these to drive chemical reactions. Minerals can introduce a number of properties to a vesicle system. The incorporation of clay particles into vesicles can provide catalytic activity that mediates both vesicle assembly and RNA oligomerization. It is known that colloidal semiconducting mineral particles can act as photocatalysts and drive redox chemistry. We show that encapsulation of these particles has the potential to provide a source of energy transduction inside vesicles, and thereby drive protocellular chemistry and represent a model system for early photosynthesis. TiO2 particles can be incorporated into vesicles and retain their photoactivity through the dehydration/rehydration cycles that have been shown to be able concentrate species inside a vesicle. It is shown that these can be used to produce biochemical species such as enzymatically active NADH in such structures. This system demonstrates a simple energy source inside vesicles/protocells suitable either for simple prebiotic systems and/or for more complex "protobiochemical" systems. It could act as a precursor to metabolic systems and provide a model of how metabolism could have developed prebiotically in a vesicle based "protocell origin of life". It can provide a source of prebiotic compounds inside vesicles, an environment considered to be of great importance for the origin of life. An energy transduction system that is simple enough to have formed at an early stage of the origin of life (even before the formation of enzymatic or ribozymal activity) makes an autotrophic origin of life easier to envision.

Summers, David; Noveron, Juan; Rodoni, David; Basa, Ranor

151

La(0.8)Sr(0.2)MnO(3-?) decorated with Ba(0.5)Sr(0.5)Co(0.8)Fe(0.2)O(3-?): a bifunctional surface for oxygen electrocatalysis with enhanced stability and activity.  

PubMed

Developing highly active and stable catalysts based on earth-abundant elements for oxygen electrocatalysis is critical to enable efficient energy storage and conversion. In this work, we took advantage of the high intrinsic oxygen reduction reaction (ORR) activity of La(0.8)Sr(0.2)MnO(3-?) (LSMO) and the high intrinsic oxygen evolution reaction (OER) activity of Ba(0.5)Sr(0.5)Co(0.8)Fe(0.2)O(3-?) (BSCF) to develop a novel bifunctional catalyst. We used pulsed laser deposition to fabricate well-defined surfaces composed of BSCF on thin-film LSMO grown on (001)-oriented Nb-doped SrTiO3. These surfaces exhibit bifunctionality for oxygen electrocatalysis with enhanced activities and stability for both the ORR and OER that rival the state-of-the-art single- and multicomponent catalysts in the literature. PMID:24649849

Risch, Marcel; Stoerzinger, Kelsey A; Maruyama, Shingo; Hong, Wesley T; Takeuchi, Ichiro; Shao-Horn, Yang

2014-04-01

152

A perfectly aligned 63 helical tubular cuprous bromide single crystal for selective photo-catalysis, luminescence and sensing of nitro-explosives.  

PubMed

A perfectly aligned 63 helical tubular cuprous bromide single crystal has been synthesized and characterized, which can selectively decompose negatively charged dyes of Methyl Orange (MO) and Kermes Red (KR), and the photocatalytic efficiency is higher than that of nanosized (?25 nm) TiO2 and ZnO. The direction and magnitude of the dipole moments as well as the band structure were calculated to reveal high photocatalytic efficiency. Moreover, luminescence studies indicate that the CuBr tube materials show very strong yellowish green emissions in the solid state and emulsion even at room temperature, and exhibit extremely high detection sensitivity towards nitro-explosives via fluorescence quenching. Detectable luminescence responses were observed at a very low concentration of 20 ppm with a high quenching efficiency of 94.90%. The results suggest that they may be promising multifunctional materials for photo-catalysis, luminescence and sensing of nitro-explosives. PMID:25601196

Yao, Ru-Xin; Hailili, Reshalaiti; Cui, Xin; Wang, Li; Zhang, Xian-Ming

2015-02-01

153

Photocatalysis Currently, the research  

E-print Network

. Processes for the production of antibiotics, various enzymes, nutritional ingredients, cytokines, antibodies and vaccines are currently under investigation. Cell Culture Technology The cultivation of mammalian cell lines of biologically active proteins (e.g. antibodies, cytokines, vaccines), for use in diagnostic and therapeutic

Vollmer, Heribert

154

Enhanced photocatalytic-electrolytic degradation of Reactive Brilliant Red X-3B in the presence of water jet cavitation.  

PubMed

Photocatalysis, electrolysis, water jet cavitation (WJC), alone and in combinations were applied to degrade an azo dye, Reactive Brilliant Red X-3B (X-3B). Experiments were conducted in a 4.0 L aqueous solution with different initial dye concentrations, TiO? dose, and solution pH. WJC substantially increased the photocatalytic, electrolytic and photocatalytic-electrolytic rates of the dye removal. The observed first-order rate of X-3B decolorization in the process of combined photocatalysis and electrolysis coupled with WJC was 1.6-2.9 times of that in the process of combined photocatalysis and electrolysis coupled with mechanical stirring. The rate enhancements may be attributed primarily to the reduced diffusion layer thickness on the electrodes and the deagglomeration of photocatalyst particles due to the chemical and physical effects of WJC. Under the conditions of 80 mg/L X-3B solution, 100 mg/L TiO? dose and solution pH 6.3, 97% and 71% of color and chemical oxygen demand (CODCr) were removed, respectively, within 90-min photocatalytic-electrolytic treatment coupled with WJC. During this process, azo groups and naphthalene, benzene and triazine structures of the dye can be destroyed. Industrial textile effluent was also investigated, and a positive synergistic effect between photocatalytic-electrolytic system and WJC was observed considering color removal. PMID:25453209

Wang, Xiaoning; Jia, Jinping; Wang, Yalin

2015-03-01

155

Highly active mixed-metal nanosheet water oxidation catalysts made by pulsed-laser ablation in liquids.  

PubMed

Surfactant-free mixed-metal hydroxide water oxidation nanocatalysts were synthesized by pulsed-laser ablation in liquids. In a series of [Ni-Fe]-layered double hydroxides with intercalated nitrate and water, [Ni1-xFex(OH)2](NO3)y(OH)x-y·nH2O, higher activity was observed as the amount of Fe decreased to 22%. Addition of Ti(4+) and La(3+) ions further enhanced electrocatalysis, with a lowest overpotential of 260 mV at 10 mA cm(-2). Electrocatalytic water oxidation activity increased with the relative proportion of a 405.1 eV N 1s (XPS binding energy) species in the nanosheets. PMID:25197774

Hunter, Bryan M; Blakemore, James D; Deimund, Mark; Gray, Harry B; Winkler, Jay R; Müller, Astrid M

2014-09-24

156

Combination of heterogeneous Fenton-like reaction and photocatalysis using Co-TiO2 nanocatalyst for activation of KHSO5 with visible light irradiation at ambient conditions.  

PubMed

A novel coupled system using Co-TiO2 was successfully designed which combined two different heterogeneous advanced oxidation processes, sulfate radical based Fenton-like reaction (SR-Fenton) and visible light photocatalysis (Vis-Photo), for degradation of organic contaminants. The synergistic effect of SR-Fenton and Vis-Photo was observed through comparative tests of 50mg/L Rhodamine B (RhB) degradation and TOC removal. The Rhodamine B degradation rate and TOC removal were 100% and 68.1% using the SR-Fenton/Vis-Photo combined process under ambient conditions, respectively. Moreover, based on XRD, XPS and UV-DRS characterization, it can be deduced that tricobalt tetroxide located on the surface of the catalyst is the SR-Fenton active site, and cobalt ion implanted in the TiO2 lattice is the reason for the visible light photocatalytic activity of Co-TiO2. Finally, the effects of the calcination temperature and cobalt concentration on the synergistic performance were also investigated and a possible mechanism for the synergistic system was proposed. This coupled system exhibited excellent catalytic stability and reusability, and almost no dissolution of Co(2+) was found. PMID:25499492

Chen, Qingkong; Ji, Fangying; Guo, Qian; Fan, Jianping; Xu, Xuan

2014-12-01

157

Solar photo-Fenton using peroxymonosulfate for organic micropollutants removal from domestic wastewater: Comparison with heterogeneous TiO2 photocatalysis.  

PubMed

This work aims at decontaminating biologically treated domestic wastewater effluents from organic micropollutants by sulfate radical based (SO4(-)) homogeneous photo-Fenton involving peroxymonosulfate as an oxidant, ferrous iron (Fe(II)) as a catalyst and simulated solar irradiation as a light source. This oxidative system was evaluated by using several probe compounds belonging to pesticides (bifenthrin, mesotrione and clothianidin) and pharmaceuticals (diclofenac, sulfamethoxazole and carbamazepine) classes and its kinetic efficiency was compared to that to the well known UV-Vis/TiO2 heterogeneous photocatalysis. Except for carbamazepine, apparent kinetic rate constants were always 10 times higher in PMS/Fe(II)/UV-Vis than in TiO2/UV-Vis system and more than 70% of total organic carbon abatement was reached in less than one hour treatment. Hydroxyl radical (OH) and SO4(-) reactivity was investigated using mesotrione as a probe compound through by-products identification by liquid chromatography-high resolution-mass spectrometry and transformation pathways elucidation. In addition to two OH based transformation pathways, a specific SO4(-) transformation pathway which first involved degradation through one electron transfer oxidation processes followed by decarboxylation were probably responsible for mesotrione degradation kinetic improvement upon UV-Vis/PMS/Fe(II) system in comparison to UVVis/TiO2 system. PMID:25108605

Ahmed, Moussa Mahdi; Brienza, Monica; Goetz, Vincent; Chiron, Serge

2014-12-01

158

Solutions Network Formulation Report. NASA's Potential Contributions for Using Solar Ultraviolet Radiation in Conjunction with Photocatalysis for Urban Air Pollution Mitigation and Increasing Air Quality  

NASA Technical Reports Server (NTRS)

This Candidate Solution is based on using NASA Earth science research on atmospheric ozone and aerosols data as a means to predict and evaluate the effectiveness of photocatalytically created surfaces (building materials like glass, tile and cement) for air pollution mitigation purposes. When these surfaces are exposed to near UV light, organic molecules, like air pollutants and smog precursors, will degrade into environmentally friendly compounds. U.S. EPA (Environmental Protection Agency) is responsible for forecasting daily air quality by using the Air Quality Index (AQI) that is provided by AIRNow. EPA is partnered with AIRNow and is responsible for calculating the AQI for five major air pollutants that are regulated by the Clean Air Act. In this Solution, UV irradiance data acquired from the satellite mission Aura and the OMI Surface UV algorithm will be used to help understand both the efficacy and efficiency of the photocatalytic decomposition process these surfaces facilitate, and their ability to reduce air pollutants. Prediction models that estimate photocatalytic function do not exist. NASA UV irradiance data will enable this capability, so that air quality agencies that are run by state and local officials can develop and implement programs that utilize photocatalysis for urban air pollution control and, enable them to make effective decisions about air pollution protection programs.

Underwood, Lauren; Ryan, Robert E.

2007-01-01

159

Optical characterization of TiO2 thin films grown by sol-gel and r.f. sputtering methods for photocatalysis applications  

NASA Astrophysics Data System (ADS)

Using the sol-gel method and the r.f. sputtering deposition technique we have grown titanium dioxide (TiO2) thin films on Corning glass substrates for photocatalysis applications. For the sol-gel method we have tried different precursors such as acetylacetone, diethanolamine, HCl and HNO3, in order to study the influence of the precursor on the structural and optical properties of the TiO2 films. For the TiO2 films grown by r.f. sputtering we changed the substrate temperature and the post-grown annealing conditions. Using X-ray diffractometry we have determined the presence of both, rutile and anatase crystalline phases in the films, and their correlation to the growth conditions. From the absorption spectra measured by spectrophotometry and photoacoustic spectroscopy we have been able to determine the bandgap energy and their dependence with the growth parameters. We present also results on the photoluminescence spectra for these sets of TiO2 thin films and discuss the origin of the different radiative emission bands, and their possible correlation to the bleaching efficiency of these films for methylene blue.

Mendoza-Alvarez, J. G.; Torres-Delgado, G.; Florido-Cuellar, A.

2005-03-01

160

TiO2 nanotube arrays grown in ionic liquids: high-efficiency in photocatalysis and pore-widening  

SciTech Connect

Debris-free, long, well-separated TiO2 nanotube arrays were obtained using an ionic liquid (IL) as electrolyte. The high conductivity of IL resulted in fast pore widening and few contaminants from electrolyte decomposition leading to high photocatalytic efficiency in water splitting.

Li, Huaqing [ORNL; Qu, Jun [ORNL; Cui, Qingzhou [ORNL; Xu, Hanbing [ORNL; Luo, Huimin [ORNL; Chi, Miaofang [ORNL; Meisner, Roberta Ann [ORNL; Wang, Wei [ORNL; Dai, Sheng [ORNL

2011-01-01

161

Destruction of Trace Organics in Otherwise Ultra Pure Water  

SciTech Connect

A number of experiments were conducted to determine the economic viability of applying various ultraviolet (UV) oxidation processes to a waste water stream containing approximately 12 mg/L total organic carbon (TOC), predominately ethylene glycol. In all experiments, a test solution was illuminated with either near-UV or a far-UV light alone or in combination with a variety of photocatalysts and oxidants. Based upon the outcomes of this project, both UV/photocatalysis and UV/ozone processes are capable of treating the water sample to below detection capabilities of TOC. However, the processes are fairly energy intensive; the most efficient case tested required 11 kWh per order of magnitude reduction in TOC per 1000 L. If energy consumption rates of 5-10 kWh/1000 L are deemed reasonable, then further investigation is recommended.

Prairie, M. R.; Stange, B. M.; Showalter, S. K.; Magrini, K. A.

1995-12-01

162

Destruction of trace organics in otherwise ultra pure water  

SciTech Connect

A number of experiments were conducted to determine the economic viability of applying various ultraviolet (UV) oxidation processes to a waste water stream containing approximately 12 mg/L total organic carbon (TOC), predominately ethylene glycol. In all experiments, a test solution was illuminated with either near-UV or a far-UV light alone or in combination with a variety of photocatalysts and oxidants. Based upon the outcomes of this project, both UV/photocatalysis and UV/ozone processes are capable of treating the water sample to below detection capabilities of TOC. However, the processes are fairly energy intensive; the most efficient case tested required 11 kWh per order of magnitude reduction in TOC per 1000 L. If energy consumption rates of 5-10 kWh/1000 L are deemed reasonable, then further investigation is recommended.

Prairie, M.R.; Stange, B.M.; Showalter, S.K. [Sandia National Labs., Albuquerque, NM (United States); Magrini, K.A. [National Renewable Energy Laboratory, Golden, CO (United States)

1995-12-01

163

Application of visible-light photocatalysis with nitrogen-doped or unmodified titanium dioxide for control of indoor-level volatile organic compounds.  

PubMed

The present study evaluated visible-light photocatalysis, applying an annular reactor coated with unmodified or nitrogen (N)-doped titanium dioxide (TiO(2)), to cleanse gaseous volatile organic compounds (VOCs) at indoor levels. The surface chemistry investigation of N-doped TiO(2) suggested that there was no significant residual of sulfate ions or urea species on the surface of the N-doped TiO(2). Under visible-light irradiation, the photocatalytic technique using N-doped TiO(2) was much superior to that for unmodified TiO(2) for the degradation of VOCs. Moreover, the degradation efficiency by a reactor coated with N-doped TiO(2) was well above 90% for four target compounds (ethyl benzene, o,m,p-xylenes), suggesting that this photocatalytic system can be effectively employed to cleanse these pollutants at indoor air quality (IAQ) levels. The degradation efficiency of all target compounds increased as the stream flow rate (SFR) decreased. For most target compounds, a reactor with a lower hydraulic diameter (HD) exhibited elevated degradation efficiency. The result on humidity effect suggested that the N-doped photocatalyst could be employed effectively to remove four target compounds (ethyl benzene, o,m,p-xylenes) under conditions of less humidified environments, including a typical indoor comfort range (50-60%). Consequently, it is suggested that with appropriate photocatalytic conditions, a visible-light-assisted N-doped photocatalytic system is clearly an important tool for improving IAQ. PMID:18809252

Jo, Wan-Kuen; Kim, Jong-Tae

2009-05-15

164

Disinfection of urban wastewater by solar driven and UV lamp - TiO? photocatalysis: effect on a multi drug resistant Escherichia coli strain.  

PubMed

The effect of TiO? photocatalysis on the inactivation of an antibiotic resistant Escherichia coli strain selected from an urban wastewater treatment plant (UWWTP) effluent was investigated. Different light sources including a 250 W wide spectrum lamp, a 125 W UV-A lamp and solar radiation, as well as, photocatalysts loadings (TiO? Degussa P25) in the range from 0.05 to 2.00 g TiO? L(-1) were evaluated. The higher efficiency (total bacterial inactivation after 10 min of irradiation) was observed in the absence of TiO? when the wastewater was irradiated using the 250 W lamp. In the presence of TiO? a decreasing inactivation trend was observed (99.76% and 72.22% inactivation after 10 min irradiation at 0.10 and 2.00 g TiO? L(-1) respectively). Under solar simulated conditions the highest inactivation efficiency (93.17%) after 10 min of irradiation was achieved at the lower photocatalyst loading (0.05 g TiO? L(-1)). The concept of "reactor optical thickness" was introduced to explain the rates of disinfection observed. The optimum photocatalyst loading estimated by radiation absorption-scattering modeling was found to be 0.1 g TiO? L(-1) for all lamps. The difference between experimental tests and modeling may be due to TiO? particles aggregation. Comparative kinetic tests between solar and solar simulated photocatalytic (SSP) processes using 0.05 g TiO? L(-1) in suspension showed a quite similar inactivation behavior up to 30 min of irradiation, but only the SSP process resulted in a total inactivation of bacteria after 60 min of exposure. Antibiotic resistant test (Kirby-Bauer) on survived colonies showed that the SSP and SP processes affected in different ways the resistance of E. coli strain to the target antibiotics. PMID:24525064

Rizzo, L; Della Sala, A; Fiorentino, A; Li Puma, G

2014-04-15

165

Visible-Light Responsive Catalysts Using Quantum Dot-Modified TiO2 for Air and Water Purification  

NASA Technical Reports Server (NTRS)

Photocatalysis, the oxidation or reduction of contaminants by light-activated catalysts, utilizing titanium dioxide (TiO2) as the catalytic substrate has been widely studied for trace contaminant control in both air and water applications. The interest in this process is due primarily to its low energy consumption and capacity for catalyst regeneration. Titanium dioxide requires ultraviolet light for activation due to its relatively large band gap energy of 3.2 eV. Traditionally, Hg-vapor fluorescent light sources are used in PCO reactors; however, the use of mercury precludes the use of this PCO technology in a spaceflight environment due to concerns over crew Hg exposure.

Coutts, Janelle L.; Hintze, Paul E.; Clausen, Christian A.; Richards, Jeffrey T.

2014-01-01

166

Fast-rate formation of TiO2 nanotube arrays in an organic bath and their applications in photocatalysis.  

PubMed

In this work, 18.5 microm titanium oxide (TiO(2)) nanotube arrays were formed by the anodization of titanium (Ti) foil in ethylene glycol containing 1 wt% water and 5 wt% fluoride for 60 min at 60 V. The fast growth rate of the nanotube arrays at 308 nm min(-1) was achieved due to the excess fluoride content and the limited amount of water in ethylene glycol used for anodization. Limited water content and excess fluoride in ethylene glycol inhibited the formation of a thick barrier layer by increasing the dissolution rate at the bottom of the nanotubes. This eased the transport of titanium, fluorine and oxygen ions, and allowed the nanotubes to grow deep into the titanium foil. At the same time, the neutral condition offered a protective environment along the tube wall and pore mouth, which minimized lateral and top dissolution. Results from x-ray photoelectron spectra revealed that the TiO(2) nanotubes prepared in ethylene glycol contained Ti, oxygen (O) and carbon (C) after annealing. The photocatalytic activity of the nanotube arrays produced was evaluated by monitoring the degradation of methyl orange. Results indicate that a nanotube with an average diameter of 140 nm and an optimal tube length of 18.5 microm with a thin tube wall (20 nm) is the optimum structure required to achieve high photocatalytic reaction. In addition, the existence of carbon, high degree of anatase crystallinity, smooth wall and absence of fluorine enhanced the photocatalytic activity of the sample. PMID:20705970

Sreekantan, Srimala; Saharudin, Khairul Arifah; Lockman, Zainovia; Tzu, Teoh Wah

2010-09-10

167

Large-Scale, Three–Dimensional, Free–Standing, and Mesoporous Metal Oxide Networks for High–Performance Photocatalysis  

PubMed Central

Mesoporous nanostructures represent a unique class of photocatalysts with many applications, including splitting of water, degradation of organic contaminants, and reduction of carbon dioxide. In this work, we report a general Lewis acid catalytic template route for the high–yield producing single– and multi–component large–scale three–dimensional (3D) mesoporous metal oxide networks. The large-scale 3D mesoporous metal oxide networks possess large macroscopic scale (millimeter–sized) and mesoporous nanostructure with huge pore volume and large surface exposure area. This method also can be used for the synthesis of large–scale 3D macro/mesoporous hierarchical porous materials and noble metal nanoparticles loaded 3D mesoporous networks. Photocatalytic degradation of Azo dyes demonstrated that the large–scale 3D mesoporous metal oxide networks enable high photocatalytic activity. The present synthetic method can serve as the new design concept for functional 3D mesoporous nanomaterials. PMID:23857595

Bai, Hua; Li, Xinshi; Hu, Chao; Zhang, Xuan; Li, Junfang; Yan, Yan; Xi, Guangcheng

2013-01-01

168

Enzymatic conversion of carbon dioxide to methanol: Enhanced methanol production in silica sol-gel matrices  

Microsoft Academic Search

Strategies for effective conversion of atmospheric COâ to methanol offer promising new technologies not only for recycling of the greenhouse gas but also for an efficient production of fuel alternatives. Partial hydrogenation of carbon dioxide has been accomplished by means of heterogeneous catalysis, electrocatalysis, and photocatalysis. Oxide-based catalysts are predominantly used for industrial fixation of carbon dioxide. A unique approach

Robyn Obert; Bakul C. Dave

1999-01-01

169

Fabrication of TiO2 film with different morphologies on Ni anode and application in photoassisted water electrolysis  

NASA Astrophysics Data System (ADS)

The anode of an alkaline electrolytic cell for water electrolysis was modified by TiO2 photocatalysts with different morphologies. The water electrolysis was coupled with photocatalytic decomposition of water by irradiation of UV light on the modified anode. And a feasible process for the hydrogen production of water electrolysis assisted by photocatalysis (WEAP) was proposed and experimentally confirmed. The results show that the highly ordered, vertically oriented tubular arrays structure on Ni anode surface has better hydrogen production performance than random TiO2. In WEAP process, the maximum rate of hydrogen production is 2.77 ml/(h*cm2) when the anode modified by ordered TiO2 nanotube arrays, compared to traditional alkaline electrolytic cell for water electrolysis with Ni anode, H2-production rate increased by 139%.

He, Hongbo; Chen, Aiping; Lv, Hui; Dong, Haijun; Chang, Ming; Li, Chunzhong

2013-02-01

170

Novel Au/La-SrTiO3 microspheres: superimposed effect of gold nanoparticles and lanthanum doping in photocatalysis.  

PubMed

Novel multielement Au/La-SrTiO(3) microspheres were synthesized by a solvothermal method using monodisperse gold and La-SrTiO(3) nanocrystals as building blocks. The porous Au/La-SrTiO(3) microspheres had a large surface area of 94.6?m(2) ?g(-1). The stable confined Au nanoparticles demonstrated strong surface plasmon resonance effect, leading to enhanced absorption in a broad UV/Vis/NIR range. Doping of rare-earth metal La also broadened the absorption band to the visible region. Both the conduction and valence bands of Au/La-SrTiO(3) microspheres thus show favorable potential for proton reduction under visible light. The superimposed effect of Au nanoparticles and La doping in Au/La-SrTiO(3) microspheres led to high photocurrent density in photoelectrochemical water splitting and good photocatalytic activity in photodegradation of rhodamine?B. The photocatalytic activities are in the order of the following: Au/La-SrTiO(3) microspheres>Au/SrTiO(3) microspheres>La-SrTiO(3) microspheres>SrTiO(3) microspheres. PMID:24817580

Wang, Guannan; Wang, Pei; Luo, He-Kuan; Hor, T S Andy

2014-07-01

171

Effect of the structure of imidazolium cations in [BF 4] ?-type ionic liquids on direct electrochemistry and electrocatalysis of horseradish peroxidase in Nafion films  

Microsoft Academic Search

The direct electrochemistry and bioelectrocatalysis of horseradish peroxidase (HRP) in Nafion films at glassy carbon electrode (GCE) was investigated in three [BF4]?-type room-temperature ionic liquids (ILs) to understand the structural effect of imidazolium cations. The three ILs are 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim][BF4]), 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) and 1-hexyl-3-methylimidazolium tetrafluoroborate ([Hmim][BF4]). A small amount of water in the three ILs is indispensable for

Lu Lu; Xirong Huang; Yinbo Qu

2011-01-01

172

Effect of the structure of imidazolium cations in [BF4](-)-type ionic liquids on direct electrochemistry and electrocatalysis of horseradish peroxidase in Nafion films.  

PubMed

The direct electrochemistry and bioelectrocatalysis of horseradish peroxidase (HRP) in Nafion films at glassy carbon electrode (GCE) was investigated in three [BF(4)](-)-type room-temperature ionic liquids (ILs) to understand the structural effect of imidazolium cations. The three ILs are 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim][BF(4)]), 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF(4)]) and 1-hexyl-3-methylimidazolium tetrafluoroborate ([Hmim][BF(4)]). A small amount of water in the three ILs is indispensable for maintaining the electrochemical activity of HRP in Nafion films, and the optimum water contents decrease with the increase of alkyl chain length on imidazole ring. Analysis shows that the optimum water contents are primarily determined by the hydrophilicity of ILs used. In contrast to aqueous medium, ILs media facilitate the direct electron transfer of HRP, and the electrochemical parameters obtained in different ILs are obviously related to the nature of ILs. The direct electron transfer between HRP and GCE is a surface-confined quasi-reversible single electron transfer process. The apparent heterogeneous electron transfer rate constant decreases gradually with the increase of alkyl chain length on imidazole ring, but the changing extent is relatively small. The electrocatalytic reduction current of H(2)O(2) at the present electrode decreases obviously with the increase of alkyl chain length, and the mass transfer of H(2)O(2) via diffusion in ILs should be responsible for the change. In addition, the modified electrode has good stability and reproducibility; the ability to tolerate high levels of F(-) has been greatly enhanced due to the use of Nafion film. When an appropriate mediator is included in the sensing layer, a sensitive nonaqueous biosensor could be fabricated. PMID:21632219

Lu, Lu; Huang, Xirong; Qu, Yinbo

2011-10-01

173

A review on catalytic applications of Au/TiO2 nanoparticles in the removal of water pollutant.  

PubMed

Nanomaterials are showing great potential for the improvement of water treatment technologies. In recent years, catalysis and photocatalysis processes using gold nanoparticles (Au-NPs) have received great attention due to their effectiveness in degrading and mineralizing organic compounds. This paper aims to review and summarize the recently published works and R & D progress in the field of photocatalytic oxidation of various water pollutants such as toxic organic compounds (i.e. azo dyes and phenols) by Au-NPs/TiO2 under solar, visible and UV irradiation. Extensive research which has focused on the enhancement of photocatalysis by modification of TiO2 employing Au-NPs is also reviewed. Moreover, the effects of various operating parameters on the photocatalytic activity of these catalysts, such as size and loading amount of Au-NPs, pH and calcination, are discussed. The support type, loading amount and particle size of deposited Au-NPs are the most important parameters for Au/TiO2 catalytic activity. Our study showed in particular that the modification of TiO2, including semiconductor coupling, can increase the photoactivity of Au/TiO2. In contrast, doping large gold NPs can mask or block the TiO2 active sites, reducing photocatalytic activity. The optimized loading amount of Au-NP varied for each experimental condition. Finally, research trends and prospects for the future are briefly discussed. PMID:24560285

Ayati, Ali; Ahmadpour, Ali; Bamoharram, Fatemeh F; Tanhaei, Bahareh; Mänttäri, Mika; Sillanpää, Mika

2014-07-01

174

Enhanced Reduced Nicotinamide Adenine Dinucleotide electrocatalysis onto multi-walled carbon nanotubes-decorated gold nanoparticles and their use in hybrid biofuel cell  

NASA Astrophysics Data System (ADS)

We report the preparation of Au nanoparticles synthetized by different protocols and supported on the surface of multi-walled carbon nanotubes containing different functional groups, focusing on their electrochemical performance towards NADH oxidation, ethanol bioelectrocatalysis, and ethanol/O2 biofuel cell. We describe four different synthesis protocols: microwave-assisted heating, water-in-oil, and dendrimer-encapsulated nanoparticles using acid or thiol species in the extraction step. The physical characterization of the metallic nanoparticles indicated that both the synthetic protocol as well as the type of functional groups on the carbon nanotubes affect the final particle size (varying from 13.4 to 2.4 nm) and their distribution onto the carbon surface. Moreover, the electrochemical data indicated that these two factors also influence their performance toward the electrooxidation of NADH. We observed that the samples containing Au nanoparticles with smaller size leads to higher catalytic currents and also shifts the oxidation potential of the targeted reaction, which varied from 0.13 to -0.06 V vs Ag/AgCl. Ethanol/O2 biofuel cell tests indicated that the hybrid bioelectrodes containing smaller and better distributed Au nanoparticles on the surface of carbon nanotubes generates higher power output, confirming that the electrochemical regeneration of NAD+ plays an important role in the overall biofuel cell performance.

Aquino Neto, S.; Almeida, T. S.; Belnap, D. M.; Minteer, S. D.; De Andrade, A. R.

2015-01-01

175

Perovskite oxides: Oxygen electrocatalysis and bulk structure  

NASA Technical Reports Server (NTRS)

Perovskite type oxides were considered for use as oxygen reduction and generation electrocatalysts in alkaline electrolytes. Perovskite stability and electrocatalytic activity are studied along with possible relationships of the latter with the bulk solid state properties. A series of compounds of the type LaFe(x)Ni1(-x)O3 was used as a model system to gain information on the possible relationships between surface catalytic activity and bulk structure. Hydrogen peroxide decomposition rate constants were measured for these compounds. Ex situ Mossbauer effect spectroscopy (MES), and magnetic susceptibility measurements were used to study the solid state properties. X ray photoelectron spectroscopy (XPS) was used to examine the surface. MES has indicated the presence of a paramagnetic to magnetically ordered phase transition for values of x between 0.4 and 0.5. A correlation was found between the values of the MES isomer shift and the catalytic activity for peroxide decomposition. Thus, the catalytic activity can be correlated to the d-electron density for the transition metal cations.

Carbonio, R. E.; Fierro, C.; Tryk, D.; Scherson, D.; Yeager, Ernest

1987-01-01

176

Competitive removal of pharmaceuticals from environmental waters by adsorption and photocatalytic degradation.  

PubMed

This work explores the competitive removal of pharmaceuticals from synthetic and environmental waters by combined adsorption-photolysis treatment. Five drugs usually present in waterways have been used as target compounds, some are pseudo-persistent pollutants (carbamazepine, clofibric acid, and sulfamethoxazole) and others are largely consumed (diclofenac and ibuprofen). The effect of the light source on adsorption of drugs onto activated carbons followed by photolysis with TiO2 was assessed, being UV-C light the most effective for drug removal in both deionized water and river water. Different composites prepared from titania nanoparticles and powdered activated carbons were tested in several combined adsorption-photocatalysis assays. The composites prepared by calcination at 400 °C exhibited much better performance than those synthesized at 500 °C, being the C400 composite the most effective one. Furthermore, some synthetic waters containing dissolved species and environmental waters were used to investigate the effect of the aqueous matrix on each drug removal. In general, photocatalyst deactivation was found in synthetic and environmental waters. This was particularly evident in the experiments performed with bicarbonate ions as well as with wastewater effluent. In contrast, tests conducted in seawater showed adsorption and photocatalytic degradation yields comparable to those obtained in deionized water. Considering the peculiarities of substrate competition in each aqueous matrix, the combined adsorption-photolysis treatment generally increased the overall elimination of drugs in water. PMID:24532206

Rioja, N; Benguria, P; Peñas, F J; Zorita, S

2014-10-01

177

Water, Water Everywhere  

ERIC Educational Resources Information Center

Everybody knows that children love water and how great water play is for children. The author discusses ways to add water to one's playscape that fully comply with health and safety regulations and are still fun for children. He stresses the importance of creating water play that provides children with the opportunity to interact with water.

Keeler, Rusty

2009-01-01

178

Water, Water Everywhere  

NSDL National Science Digital Library

This is a short NASA video on the water cycle. The video shows the importance of the water cycle to nearly every natural process on Earth and illustrates how tightly coupled the water cycle is to climate.

Nasa

179

Ru dye functionalized Au-SiO2@TiO2 and Au/Pt-SiO2@TiO2 nanoassemblies for surface-plasmon-induced visible light photocatalysis.  

PubMed

The most commonly used material in photocatalysis is TiO2. Since TiO2 absorbs only UV-light, photosensitizers are used to extend these catalysts' absorption properties into the Vis/NIR spectral range. In this work we merge the commonly used approach of dye sensitization with the only recently developed approach of functionalizing the catalyst with plasmonically active metal nanoparticles in order to achieve synergistic effects between these two types of visible light sensitization. To this end SiO2@TiO2 nanostructures are functionalized with gold nanoparticles or a combination of gold/platinum nanoparticles loaded with Ru dyes and thoroughly characterized by means of transmission electron microscopy (TEM) and scanning electron microscopy (SEM) imaging as well as energy dispersive X-ray spectroscopy (EDX), UV/VIS and surface enhanced resonance Raman scattering (SERRS) spectroscopy. The photocatalytic performance is tested by applying the benchmark experiment of methylene blue degradation. Spectroscopic investigations and electron microscopy proof the successful synthesis of the envisioned structure. The photocatalytic activity of the nanostructures shows up to 52% higher first order rate constants compared to the corresponding nanostructures without further dye functionalization. PMID:24594039

Theil, Frank; Dellith, Andrea; Dellith, Jan; Undisz, Andreas; Csáki, Andrea; Fritzsche, Wolfgang; Popp, Jürgen; Rettenmayr, Markus; Dietzek, Benjamin

2014-05-01

180

Rapid synthesis, structure and photocatalysis of pure bismuth A-site perovskite of Bi(Mg3/8Fe2/8Ti3/8)O3.  

PubMed

Bi(Mg3/8Fe2/8Ti3/8)O3, a member of a small group of pure Bi(3+) A site perovskites, exhibiting a high ferroelectric Curie point (Tc), was rapidly synthesized by a sample method of molten salt synthesis. The purity of Bi(Mg3/8Fe2/8Ti3/8)O3 samples is directly affected by the reaction conditions such as the soaking temperature, and the heating and cooling rates. The as-prepared Bi(Mg3/8Fe2/8Ti3/8)O3 particles are well-formed, cube-shaped single-crystals with sizes ranging from 200-300 nm. The chemical states of Bi and Fe ions are Bi(3+) and Fe(3+) in Bi(Mg3/8Fe2/8Ti3/8)O3. UV-vis diffuse reflectance spectra and preliminary photocatalytic experiments indicate that the pure Bi(3+) A site perovskite of Bi(Mg3/8Fe2/8Ti3/8)O3 has a suitable energy bandgap (1.86 eV) and shows obvious photocatalytic activity for the decolorization of methyl blue under visible-light irradiation. The present work suggests potential future applications of Bi(Mg3/8Fe2/8Ti3/8)O3 in photocatalysis and ferroelectric photovoltaic effects. PMID:24818220

Zhang, Wenjuan; Chen, Jun; An, Xiaoxin; Wang, Qi; Fan, Longlong; Wang, Fangfang; Deng, Jinxia; Yu, Ranbo; Xing, Xianran

2014-06-28

181

Effect of water composition on TiO2 photocatalytic removal of endocrine disrupting compounds (EDCs) and estrogenic activity from secondary effluent.  

PubMed

The effect of inorganic ions and dissolved organic matter (DOM) on the TiO(2) photocatalytic removal of estrogenic activity from secondary effluents of municipal wastewater treatment plants was investigated. The presence of HPO(4)(2-), NH(4)(+), and HCO(3)(-) resulted in a significantly negative impact on the photocatalytic removal of estrogenic activity from synthetic water due to their strong adsorption on the surface of TiO(2). However, only a weak impact was noted during photocatalytic removal of estrogenic activity from secondary effluent with these ions added, since the presence of DOM in real wastewater played a more important role in inhibiting photocatalytic removal of estrogenic activity than inorganic ions. By investigating the effect of different DOM fractions on photocatalytic removal of estrogenic activity, polar compounds (PC) were found to cause a temporary increase in estrogenic activity during TiO(2) photocatalysis. Fluorescence spectroscopy and molecular weight (MW) analysis on secondary effluent spiked with PC during TiO(2) photocatalysis suggest that large MW organic matter (>4.5kDa) in secondary effluent, such as humic/fulvic acid, not only could play an important role in inhibiting photocatalytic removal of estrogenic activity but also is responsible for the temporary increase in estrogenic activity during the same process. PMID:22436342

Zhang, Wenlong; Li, Yi; Su, Yaling; Mao, Kai; Wang, Qing

2012-05-15

182

Achieving solar overall water splitting with hybrid photosystems of photosystem II and artificial photocatalysts  

NASA Astrophysics Data System (ADS)

Solar overall water splitting is a promising sustainable approach for solar-to-chemical energy conversion, which harnesses solar irradiation to oxidize water to oxygen and reduce the protons to hydrogen. The water oxidation step is vital but difficult to achieve through inorganic photocatalysis. However, nature offers an efficient light-driven water-oxidizing enzyme, photosystem II (PSII). Here we report an overall water splitting natural-artificial hybrid system, in which the plant PSII and inorganic photocatalysts (for example, Ru/SrTiO3:Rh), coupled with an inorganic electron shuttle [Fe(CN)63-/Fe(CN)64-], are integrated and dispersed in aqueous solutions. The activity of this hybrid photosystem reaches to around 2,489?mol H2 (mol PSII)-1?h-1 under visible light irradiation, and solar overall water splitting is also achieved under solar irradiation outdoors. The optical imaging shows that the hybrid photosystems are constructed through the self-assembly of PSII adhered onto the inorganic photocatalyst surface. Our work may provide a prototype of natural-artificial hybrids for developing autonomous solar water splitting system.

Wang, Wangyin; Chen, Jun; Li, Can; Tian, Wenming

2014-08-01

183

Acidic Ionic Liquid/Water Solution as Both Medium and Proton Source for Electrocatalytic H2 Evolution by [Ni(P2N2)2]2+ Complexes  

SciTech Connect

The electrocatalytic reduction of protons to H2 by [Ni(PPh2NC6H4-hex2)2](BF4)2 (where PPh2NC6H4-hex2 = 1,5-di(4-n-hexylphenyl)-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane) in the highly acidic ionic liquid dibutylformamidium bis(trifluoromethanesulfonyl)amide shows a strong dependence on added water. A turnover frequency of 43,000-53,000 s-1 has been measured for hydrogen production at 25 °C when the mole fraction of water (?H2O) is 0.72. The same catalyst in acetonitrile with added dimethylformamidium trifluoromethanesulfonate and water has a turnover frequency of 720 s?1. Thus the use of an ionic liquid/aqueous solution enhances the observed catalytic rates by more than a factor of 50 compared to acids in traditional organic solvents such as acetonitrile. Complexes [Ni(PPh2NC6H4X2)2](BF4)2 (X = H, OMe, CH2P(O)(OEt)2, Br) are also catalysts in the ionic liquid/water mixture, and the observed catalytic rates correlate with the hydrophobicity of X. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy.

Pool, Douglas H.; Stewart, Michael P.; O'Hagan, Molly J.; Shaw, Wendy J.; Roberts, John A.; Bullock, R. Morris; DuBois, Daniel L.

2012-09-25

184

Evaluation of the Role of Water in the H2 Bond Formation by Ni(II)-based Electrocatalysts  

SciTech Connect

We investigate the role of water in the H-H bond formation by a family of nickel molecular catalysts that exhibit high rates for H2 production in acetonitrile solvent. A key feature leading to the high reactivity is the Lewis acidity of the Ni(II) center and pendant amines in the diphosphine ligand that function as Lewis bases, facilitating H-H bond formation or cleavage. Significant increases in the rate of H2 production have been reported in the presence of added water. Our calculations show that molecular water can displace an acetonitrile solvent molecule in the first solvation shell of the metal. One or two water molecules can also participate in shuttling a proton that can combine with a metal hydride to form the H-H bond. However the participation of the water molecules does not lower the barrier to H-H bond formation. Thus these calculations suggest that the rate increase due to water in these electrocatalysts is not associated with the elementary step of H-H bond formation or cleavage, but rather with the proton delivery steps. We attribute the higher barrier in the H-H bond formation in the presence of water to a decrease in direct interaction between the protic and hydridic hydrogen atoms forced by the water molecules. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences. Computational resources were provided at W. R. Wiley Environmental Molecular Science Laboratory - Pacific Northwest National Laboratory, the National Energy Research Scientific Computing Center (NERSC) at Lawrence Berkeley National Laboratory, and the Jaguar supercomputer at Oak Ridge National Laboratory.

Ho, Ming-Hsun; Raugei, Simone; Rousseau, Roger J.; Dupuis, Michel; Bullock, R. Morris

2013-07-17

185

LC/MS/MS structure elucidation of reaction intermediates formed during the TiO2 photocatalysis of microcystin-LR  

EPA Science Inventory

Microcystin-LR (MC-LR), a cyanotoxin and emerging drinking water contaminant, was treated with TiO(2) photocatalysts immobilized on stainless steel plates as an alternative to nanoparticles in slurry. The reaction intermediates of MC-LR were identified with mass spectrometry (MS)...

186

Water, water everywhere  

Microsoft Academic Search

The first part of this article describes the current understanding of the dynamic interaction between protein folding and function and water, dependent on the polarity of water. The second part examines the role of water in converting organic matter into oil and coal by summarizing the history and result of experiments done over the last 13 years by Exxon researchers.

Pennisi

1993-01-01

187

Effect of Coadsorbed Water on the Photodecomposition of Acetone on TiO2(110)  

SciTech Connect

The influence of coadsorbed water on the photodecomposition of acetone on TiO2 was examined using temperature programmed desorption (TPD) and the rutile TiO2(110) surface as a model photocatalyst. Of the two major influences ascribed to water in the heterogeneous photocatalysis literature (promotion via OH radical supply and inhibition due to site blocking), only the negative influence of water was observed. As long as the total water and acetone coverage was maintained well below the first layer saturation coverage (‘1 ML’), little inhibition of acetone photodecomposition was observed. However, as the total water+acetone coverage exceeded 1 ML, acetone was preferentially displaced from the first layer to physisorbed states by water and the extent of acetone photodecomposition attenuated. The displacement originated from water compressing acetone into high coverage regions where increased acetone-acetone repulsions caused displacement from the first layer. The immediate product of acetone photodecomposition was adsorbed acetate, which occupies twice as many surface sites per molecule as compared to acetone. Since the acetate intermediate was more stable on the TiO2(110) surface than either water or acetone (as gauged by TPD) and since its photodecomposition rate was less than that of acetone, additional surface sites were not opened up during acetone photodecomposition for previously displaced acetone molecules to re-enter the first layer. Results in this study suggest that increased molecular-level repulsions between organic molecules brought about by increased water coverage are as influential in the inhibiting effect of water on photooxidation rates as are water-organic repulsions.

Henderson, Michael A.

2008-06-10

188

Heterogeneous photocatalytic disinfection of wash waters from the fresh-cut vegetable industry.  

PubMed

The effectiveness of photocatalytic disinfection for control of natural and potentially pathogenic microflora in wash waters used for fresh-cut vegetables was evaluated. Wash waters for lettuce, escarole, chicory, carrot, onion, and spinach from a fresh-cut vegetable processing plant were treated with a titanium dioxide (TiO2) photocatalytic system. The vegetable wash waters were impelled out with a pump at a flow rate of 1,000 liters/h and conducted through a stainless steel circuit to the filtration system to reach the TiO2 photocatalyst fiber, which was illuminated with a 40-W UV-C lamp. The microbial and physicochemical qualities of the wash water were analyzed. Heterogeneous photocatalysis was an effective disinfection method, reducing counts of bacteria, molds, and yeasts. Most of the treated wash waters had total bacteria reductions of 4.1 +/- 1.3 to 4.8 +/- 0.4 log CFU/ml after 10 min of treatment when compared with untreated water. Higher decontamination efficacy was observed in carrot wash water (6.2 +/- 0.1-log reductions), where turbidity and organic matter were lower than those in the wash waters for other vegetables. The tested heterogeneous photocatalytic system also was effective for reducing water turbidity, although chemical oxygen demand was unaffected after the treatments. The efficacy of the photocatalytic system for reducing microbial load depended on the physicochemical characteristics of the wash water, which depended on the vegetable being washed. The conclusions derived from this study illustrate that implementation of a heterogeneous photocatalytic system in the fresh-cut vegetable washing processes could allow the reuse of wash water. PMID:18326177

Selma, María Victoria; Allende, Ana; López-Gálvez, Francisco; Conesa, María Angeles; Gil, María Isabel

2008-02-01

189

Water Resources Water Quality and Water Treatment  

E-print Network

PLANTS WATER TRE WATER QUALITY MONITORING NETWORK I Central Pollution Control Board (CPCB) hasEF) promotes basin-wide pollution control strategies. It liaises with State Water Pollution Control BoardsWater Resources TD 603 Lecture 1: Water Quality and Water Treatment CTARA Indian Institute

Sohoni, Milind

190

Drinking Water  

MedlinePLUS

... the safest water supplies in the world, but drinking water quality can vary from place to place. It ... water supplier must give you annual reports on drinking water. The reports include where your water came from ...

191

Environmentally Responsible Use of Nanomaterials for the Photocatalytic Reduction of Nitrate in Water  

NASA Astrophysics Data System (ADS)

Nitrate is the most prevalent water pollutant limiting the use of groundwater as a potable water source. The overarching goal of this dissertation was to leverage advances in nanotechnology to improve nitrate photocatalysis and transition treatment to the full-scale. The research objectives were to (1) examine commercial and synthesized photocatalysts, (2) determine the effect of water quality parameters (e.g., pH), (3) conduct responsible engineering by ensuring detection methods were in place for novel materials, and (4) develop a conceptual framework for designing nitrate-specific photocatalysts. The key issues for implementing photocatalysis for nitrate drinking water treatment were efficient nitrate removal at neutral pH and by-product selectivity toward nitrogen gases, rather than by-products that pose a human health concern (e.g., nitrite). Photocatalytic nitrate reduction was found to follow a series of proton-coupled electron transfers. The nitrate reduction rate was limited by the electron-hole recombination rate, and the addition of an electron donor (e.g., formate) was necessary to reduce the recombination rate and achieve efficient nitrate removal. Nano-sized photocatalysts with high surface areas mitigated the negative effects of competing aqueous anions. The key water quality parameter impacting by-product selectivity was pH. For pH < 4, the by-product selectivity was mostly N-gas with some NH4 +, but this shifted to NO2- above pH = 4, which suggests the need for proton localization to move beyond NO2 -. Co-catalysts that form a Schottky barrier, allowing for localization of electrons, were best for nitrate reduction. Silver was optimal in heterogeneous systems because of its ability to improve nitrate reduction activity and N-gas by-product selectivity, and graphene was optimal in two-electrode systems because of its ability to shuttle electrons to the working electrode. "Environmentally responsible use of nanomaterials" is to ensure that detection methods are in place for the nanomaterials tested. While methods exist for the metals and metal oxides examined, there are currently none for carbon nanotubes (CNTs) and graphene. Acknowledging that risk assessment encompasses dose-response and exposure, new analytical methods were developed for extracting and detecting CNTs and graphene in complex organic environmental (e.g., urban air) and biological matrices (e.g. rat lungs).

Doudrick, Kyle

192

UNL WATER CENTER WATER CURRENT  

E-print Network

INSIDE UNL WATER CENTER WATER CURRENT PROTECTING NEBRASKA'S WATER RESOURCES THROUGH RESEARCH................ Guest Column 10..............Water News Briefs 11..............Calendar 12..............Free Lectures Continue Summer Water/Natural Resources Tour Examines Republican River Issues by Steve Ress This summer

Nebraska-Lincoln, University of

193

UNL WATER CENTER WATER CURRENT  

E-print Network

INSIDE UNL WATER CENTER WATER CURRENT PROTECTING NEBRASKA'S WATER RESOURCES THROUGH RESEARCH Assessment on Atrazine 10...................Water News Briefs 12...................April Faculty Forum Summer Water and Natural Resources Tour Examines North Platte River Issues by Steve Ress The University

Nebraska-Lincoln, University of

194

UNL WATER CENTER WATER CURRENT  

E-print Network

INSIDE UNL WATER CENTER WATER CURRENT PROTECTING NEBRASKA'S WATER RESOURCES THROUGH RESEARCH.....................Meet the Faculty 4.....................GuestColumn 5.....................WaterSupplySecurity 7...................Nebraska Depletions Plan 10 ..................Water News Briefs 11 ..................Calendar 12

Nebraska-Lincoln, University of

195

Inactivation of Amphidinium sp. in ballast waters using UV/Ag-TiO2+O3 advanced oxidation treatment.  

PubMed

Ballast water poses a biological threat to the world's waterways by transferring aquatic species from one body of water to another. This study investigates the use of combined ultraviolet (UV)/Ag-TiO(2)+ozone (O(3)) processes for treating ballast water using Amphidinium sp. as an indicator microorganism. Sufficient Amphidinium sp. cells in ballast waters can be inactivated using O(3) alone, UV irradiation alone (with or without an Ag-TiO(2) coating), and combined treatments. For the low inactivation ratio (<40%) regime, the effects of ozonation and photocatalysis were observed to be cumulative. The combined UV/Ag-TiO(2)+O(3) treatment produced excess hydroxyl radicals and total residual oxidants (TROs), and readily damaged cell membranes to release intracellular substances. The comparison tests revealed that the combined treatments synergistically inactivate Escherichia coli in ballast waters. However, the combined process did not synergistically inactivate Amphidinium sp. cells. Inactivating different aqua species in ballast waters needs distinct treatment methods and dosages. PMID:21890347

Wu, Donghai; You, Hong; Zhang, Ran; Chen, Chuan; Lee, Duu-Jong

2011-11-01

196

Photo-catalysis of bromacil under simulated solar light using Au/TiO2: evaluation of main degradation products and toxicity implications.  

PubMed

Bromacil (5-bromo-3-sec-butyl-6-methyluracil) is a substituted uracil herbicide used worldwide. It is not readily biodegradable and has the potential to contaminate different types of water bodies with possible impact on diverse non-target species. In this work, degradation of bromacil in aqueous Au/TiO2 suspension under simulated sunlight allowed fourteen degradation products to be identified. The photodegradation of bromacil followed (pseudo) first order kinetics in the presence of 0.2 g L(-1) of Au/TiO2 with a half-life of 25.66?±?1.60 min and a rate constant of 0.0271?±?0.0023 min(-1). Transformation routes of the photo-catalytic degradation of bromacil were then proposed. Complementary toxicity assessment of the treated bromacil solution revealed a marked decrease in toxicity, thereby confirming that by-products formed would be less harmful from an environmental point of view. Photo-catalytic degradation of bromacil thus appears to hold promise as a cost-effective treatment technology to diminish the presence of this herbicide in aquatic systems. PMID:25163558

Angthararuk, Dusit; Sutthivaiyakit, Pakawadee; Blaise, Christian; Gagné, François; Sutthivaiyakit, Somyote

2015-01-01

197

Water, Water, Everywhere.  

ERIC Educational Resources Information Center

The brain needs energy, oxygen, and water to operate. Access to the bathroom pass can become a major conflict between teachers and students and has great potential for disrupting classes. The classroom can be humanized by granting more bathroom passes and allowing water bottles. (MLH)

Fahey, John A.

2000-01-01

198

Water, Water, Everywhere.  

ERIC Educational Resources Information Center

Water is a major component in many consumer products. Azeotropic distillation of products such as detergents and foodstuffs to form a two-phase distillate is a simple experimental method to determine the percentage of water in the product. (Author/GA)

Selinger, Ben

1979-01-01

199

Photocatalytic oxidation of aqueous ammonia in model gray waters.  

PubMed

This study investigated the TiO2 photocatalytic degradation of aqueous ammonia (NH4+/NH3) in the presence of surfactants and monosaccharides at pH approximately 10.1. Initial rates of NH4+/NH3 photocatalytic degradation decreased by approximately 50-90% in the presence of anionic, cationic, and nonionic surfactants and monosaccharides. Through correlation analysis, we concluded that scavenging of hydroxyl radical (.OH) by the products of surfactant/monosaccharide photocatalytic degradation, including carbonate and formate, could explain approximately 80% of the variance in initial rates of NH4+/NH3 removal in our system. Addition of a supplemental .OH source (H2O2) enhanced the rate of NH4+/NH3 degradation in the presence of the surfactant Brij 23 lauryl ether (Brij 35), further supporting the idea that .OH scavenging is the mechanism by which surfactants and monosaccharides decreased initial rates of NH4+/NH3 photocatalytic degradation. Despite slowed rates of NH4+/NH3 degradation, both surfactants/monosaccharides and NH4+/NH3 were removed by TiO2 photocatalysis, indicating that this process can effectively remove both carbonaceous and nitrogenous biochemical oxygen demand from gray water. PMID:18336859

Zhu, Xingdong; Nanny, Mark A; Butler, Elizabeth C

2008-05-01

200

Preparation of magnetic Fe{sub 3}O{sub 4}/SiO{sub 2}/Bi{sub 2}WO{sub 6} microspheres and their application in photocatalysis  

SciTech Connect

Graphical abstract: Display Omitted Highlights: ? We described the preparation and characterization of the Fe{sub 3}O{sub 4}/SiO{sub 2}/Bi{sub 2}WO{sub 6} magnetic microspheres composites. ? The photocatalytic activities of the composites were also investigated. ? With the combination of photocatalysts and Fe{sub 3}O{sub 4}/SiO{sub 2}, good stability and magnetic separability can be achieved. ? And to the best of our knowledge, this is the first report concerning Bi{sub 2}WO{sub 6} nanoparticles loaded on Fe{sub 3}O{sub 4}/SiO{sub 2} particles. -- Abstract: Magnetic Fe{sub 3}O{sub 4}/SiO{sub 2}/Bi{sub 2}WO{sub 6} microspheres with photocatalytic properties have been synthesized using a silica layer for “bonding” (adhering Bi{sub 2}WO{sub 6} to Fe{sub 3}O{sub 4}). The morphology, composition and magnetic properties of the Fe{sub 3}O{sub 4}/SiO{sub 2}/Bi{sub 2}WO{sub 6} composites were characterized by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, vibrating sample magnetometry, and BET surface area analysis. The activity of the material in photocatalytic decoloration of aqueous rhodamine B (RhB) solution under visible light was evaluated. The results showed that Bi{sub 2}WO{sub 6} combined well with the magnetic Fe{sub 3}O{sub 4}/SiO{sub 2} nanoparticles. The Fe{sub 3}O{sub 4}/SiO{sub 2}/Bi{sub 2}WO{sub 6} composites were spherical in shape, having a mean size of 2 ?m. The spent catalyst could be recycled with only slight decline in catalytic activity. It is envisaged that the stability, reusability, and magnetic nature of the Fe{sub 3}O{sub 4}/SiO{sub 2}/Bi{sub 2}WO{sub 6} catalyst warrants its application in photocatalysis.

Chen, Su-Hua; Yin, Zhen [Key Laboratory of Jiangxi Province for Ecological Diagnosis-Remediation and Pollution Control, Nanchang Hangkong University, Nanchang 330063 (China)] [Key Laboratory of Jiangxi Province for Ecological Diagnosis-Remediation and Pollution Control, Nanchang Hangkong University, Nanchang 330063 (China); Luo, Sheng-Lian, E-mail: sllou@hnu.edu.cn [Key Laboratory of Jiangxi Province for Ecological Diagnosis-Remediation and Pollution Control, Nanchang Hangkong University, Nanchang 330063 (China)] [Key Laboratory of Jiangxi Province for Ecological Diagnosis-Remediation and Pollution Control, Nanchang Hangkong University, Nanchang 330063 (China); Au, Chak-Tong [Key Laboratory of Jiangxi Province for Ecological Diagnosis-Remediation and Pollution Control, Nanchang Hangkong University, Nanchang 330063 (China) [Key Laboratory of Jiangxi Province for Ecological Diagnosis-Remediation and Pollution Control, Nanchang Hangkong University, Nanchang 330063 (China); Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong (China); Li, Xue-Jun [Key Laboratory of Jiangxi Province for Ecological Diagnosis-Remediation and Pollution Control, Nanchang Hangkong University, Nanchang 330063 (China)] [Key Laboratory of Jiangxi Province for Ecological Diagnosis-Remediation and Pollution Control, Nanchang Hangkong University, Nanchang 330063 (China)

2013-02-15

201

Water, water everywhere  

SciTech Connect

The first part of this article describes the current understanding of the dynamic interaction between protein folding and function and water, dependent on the polarity of water. The second part examines the role of water in converting organic matter into oil and coal by summarizing the history and result of experiments done over the last 13 years by Exxon researchers. Water under pressure and at high temperatures (300 C) can act as a solvent, a catalyst, and a reagent. Organic molecules can be fragmented by high temperature, but water and brine can also fragment them, sometimes more effectively. The actual mechanism by which water works is still a matter of active investigation, but the fact that it can be involved in oil formation could weak havoc on established ideas. Among the possibilities in the immediate future using hot water include the following: introducing hydrogen to coal for easier liquefaction and cost reduction; add hydrogen to low quality oil deposits for better quality and easier extraction; increasing the efficiency of isopropyl alcohol production; breaking down petroleum based wastes to reduce environmental contamination.

Pennisi, E.

1993-02-20

202

Water Works.  

ERIC Educational Resources Information Center

Describes a two-day field trip, along with follow-up classroom activities and experiments which relate to water resources and water quality. Discusses how trips to a lake and water treatment facilities can enhance appreciation of water. (TW)

Van De Walle, Carol

1988-01-01

203

Water, Water Everywhere!  

ERIC Educational Resources Information Center

Describes how problems with water drainage on the playground, and the resulting puddles, provided a wealth of learning opportunities, children's fun, family-school communication, and challenges for one early childhood program. (KB)

Sible, Kathleen P.

2000-01-01

204

Ground Water  

NSDL National Science Digital Library

USGS Water Science for Schools explaines the uses of ground water in the United States. The main uses of ground water include "irrigation uses, drinking-water and other public uses, and for supplying domestic water to people who do not receive public-supply water." Check out this site to learn more.

205

Computational and experimental study of the mechanism of hydrogen generation from water by a molecular molybdenum-oxo electrocatalyst.  

PubMed

We investigate the mechanism for the electrocatalytic generation of hydrogen from water by the molecular molybdenum-oxo complex, [(PY5Me(2))MoO](2+) (PY5Me(2) = 2,6-bis(1,1-bis(2-pyridyl)ethyl)pyridine). Computational and experimental evidence suggests that the electrocatalysis consists of three distinct electrochemical reductions, which precede the onset of catalysis. Cyclic voltammetry studies indicate that the first two reductions are accompanied by protonations to afford the Mo-aqua complex, [(PY5Me(2))Mo(OH(2))](+). Calculations support hydrogen evolution from this complex upon the third reduction, via the oxidative addition of a proton from the bound water to the metal center and finally an ?-H abstraction to release hydrogen. Calculations further suggest that introducing electron-withdrawing substituents such as fluorides in the para positions of the pyridine rings can reduce the potential associated with the reductive steps, without substantially affecting the kinetics. After the third reduction, there are kinetic bottlenecks to the formation of the Mo-hydride and subsequent hydrogen release. Computational evidence also suggests an alternative to direct ?-H abstraction as a mechanism for H(2) release which exhibits a lower barrier. The new mechanism is one in which a water acts as an intramolecular proton relay between the protons of the hydroxide and the hydride ligands. The calculated kinetics are in reasonable agreement with experimental measurements. Additionally, we propose a mechanism for the stoichiometric reaction of [(PY5Me(2))Mo(CF(3)SO(3))](+) with water to yield hydrogen and [(PY(5)Me(2))MoO](2+) along with the implications for the viability of an alternate catalytic cycle involving just two reductions to generate the active catalyst. PMID:22356562

Sundstrom, Eric J; Yang, Xinzheng; Thoi, V Sara; Karunadasa, Hemamala I; Chang, Christopher J; Long, Jeffrey R; Head-Gordon, Martin

2012-03-21

206

Identifying active surface phases for metal oxide electrocatalysts: a study of manganese oxide bi-functional catalysts for oxygen reduction and water oxidation catalysis.  

PubMed

Progress in the field of electrocatalysis is often hampered by the difficulty in identifying the active site on an electrode surface. Herein we combine theoretical analysis and electrochemical methods to identify the active surfaces in a manganese oxide bi-functional catalyst for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). First, we electrochemically characterize the nanostructured ?-Mn(2)O(3) and find that it undergoes oxidation in two potential regions: initially, between 0.5 V and 0.8 V, a potential region relevant to the ORR and, subsequently, between 0.8 V and 1.0 V, a potential region between the ORR and the OER relevant conditions. Next, we perform density function theory (DFT) calculations to understand the changes in the MnO(x) surface as a function of potential and to elucidate reaction mechanisms that lead to high activities observed in the experiments. Using DFT, we construct surface Pourbaix and free energy diagrams of three different MnO(x) surfaces and identify 1/2 ML HO* covered Mn(2)O(3) and O* covered MnO(2), as the active surfaces for the ORR and the OER, respectively. Additionally, we find that the ORR occurs through an associative mechanism and that its overpotential is highly dependent on the stabilization of intermediates through hydrogen bonds with water molecules. We also determine that OER occurs through direct recombination mechanism and that its major source of overpotential is the scaling relationship between HOO* and HO* surface intermediates. Using a previously developed Sabatier model we show that the theoretical predictions of catalytic activities match the experimentally determined onset potentials for the ORR and the OER, both qualitatively and quantitatively. Consequently, the combination of first-principles theoretical analysis and experimental methods offers an understanding of manganese oxide oxygen electrocatalysis at the atomic level, achieving fundamental insight that can potentially be used to design and develop improved electrocatalysts for the ORR and the OER and other important reactions of technological interest. PMID:22990481

Su, Hai-Yan; Gorlin, Yelena; Man, Isabela C; Calle-Vallejo, Federico; Nørskov, Jens K; Jaramillo, Thomas F; Rossmeisl, Jan

2012-10-28

207

UNL WATER CENTER WATER CURRENT  

E-print Network

INSIDE UNL WATER CENTER WATER CURRENT PROTECTING NEBRASKAíS WATER RESOURCES THROUGH RESEARCH the Faculty 4................ Guest Column 5................ Clean Water Act 6................ Water News in Empty Hog Barns by Steve Ress, UNL Water Center Jim Rosowski sees potential for a freshwater farming

Nebraska-Lincoln, University of

208

UNL WATER CENTER WATER CURRENT  

E-print Network

INSIDE UNL WATER CENTER WATER CURRENT PROTECTING NEBRASKA'S WATER RESOURCES THROUGH RESEARCHGroundwaterRecharge 6-7 ............ NebraskaWaterMarketingPolicyChoices 10 .............Water News Briefs 11 sites visited on July's water and natural resources tour (photo: Kyle Hoagland). (continued on page 9

Nebraska-Lincoln, University of

209

Earth's Water  

NSDL National Science Digital Library

This resource provides an overview of the distribution and occurence of water on Earth. Topics include where and how much water there is, the water cycle, and how water is measured. There is also discussion of characteristics and distribution of surface water, groundwater, glaciers, and icecaps.

210

Water Conditioner  

NASA Technical Reports Server (NTRS)

A home use water treatment incorporates technology developed to purify water aboard Space Shuttle Orbiters. The General Ionics Model IQ Bacteriostatic Water Softener softens water and inhibits bacteria growth in the filtering unit. Ionics used NASA silver ion technology as a basis for development of a silver carbon dense enough to remain on top of the water softening resin bed.

1991-01-01

211

Drinking Water  

NSDL National Science Digital Library

This tutorial introduces students to the importance of water to living organisms, including humans. The discussion points out that all organisms contain water, and decribes how water is accumulated and stored. There is also an examination of the water supplies of Winnipeg, Ontario, and Vancouver, British Columbia, and a discussion of the importance of purifying driking water supplies to remove harmful bacteria and microbes.

212

Ground Water  

NSDL National Science Digital Library

This USGS site contains very useful descriptions about many aspects of ground water. The major topics include Ground Water, How Ground Water Occurs, Quality of Ground Water, Appraising the Nation's Ground-Water Resources, and a Glossary. This is a non-technical site, designed for use by the general public. Several charts and diagrams are also included in this site.

2002-02-15

213

Parasites: Water  

MedlinePLUS

... every day. Not only do all people need drinking water to survive, but water plays an important role ... been contaminated by certain parasites. For example, individuals drinking water contaminated with fecal matter containing the ameba Entamoeba ...

214

Water Treatment  

NSDL National Science Digital Library

Water treatment on a large scale enables the supply of clean drinking water to communities. In this activity, learners develop methods to clean a polluted water sample, describe components of a water treatment process, and learn how humans impact Earth's freshwater supply. The activity simulates methods used in real water treatment including aeration, coagulation, sedimentation, filtration and disinfection. This activity would be an excellent adjunct to a guided tour of a local water treatment plant.

Jersey, New; Center, Liberty S.; Coalition, New J.

2006-01-01

215

Drinking Water  

NSDL National Science Digital Library

This publication, authored by Thodore B. Shelton of Rutgers University, summarizes the information necessary for interpreting drinking water quality analyses performed by water testing laboratories. It focuses on testing results obtained from drinking water supplies from public water systems and non-public water systems (home wells). It is intended primarily for homeowners, but environmental organizations, health departments, and commercial water testing laboratories and others should find this material of interest and value.

Shelton, Thodore B.

216

Spectroscopic investigation of the mechanism of photocatalysis.  

PubMed

Reaction mechanisms of various kinds of photocatalysts have been reviewed based on the recent reports, in which various spectroscopic techniques including luminol chemiluminescence photometry, fluorescence probe method, electron spin resonance (ESR), and nuclear magnetic resonance (NMR) spectroscopy were applied. The reaction mechanisms elucidated for bare and modified TiO2 were described individually. The modified visible light responsive TiO2 photocatalysts, i.e., Fe(III)-deposited metal-doped TiO2 and platinum complex-deposited TiO2, were studied by detecting paramagnetic species with ESR, •O2- (or H2O2) with chemiluminescence photometry, and OH radicals with a fluorescence probe method. For bare TiO2, the difference in the oxidation mechanism for the different crystalline form was investigated by the fluorescence probe method, while the adsorption and decomposition behaviors of several amino acids and peptides were investigated by 1H-NMR spectroscopy. PMID:25387352

Nosaka, Yoshio; Nishikawa, Masami; Nosaka, Atsuko Y

2014-01-01

217

Microwaves in Photochemistry and Photocatalysis Vladimir Cirkva  

E-print Network

become an important field of modern organic chemistry [5­9]. Chemical processes performed under ground-state chemistry cannot. Unfortunately, photoinduced reactions are only slowly being accepted, ultrasound, high pressure, mechanical activation, supercritical fluids, electrochem- istry, or plasma

Cirkva, Vladimir

218

UNL WATER CENTER WATER CURRENT  

E-print Network

INSIDE UNL WATER CENTER WATER CURRENT PROTECTING NEBRASKA'S WATER RESOURCES THROUGH RESEARCH................ Sidney Area Deals with Drought 6................ Water and Electricity Are Inseparable 10's School of Natural Resource Sciences,Conservation and Survey Division and Water Center into the School

Nebraska-Lincoln, University of

219

UNL WATER CENTER WATER CURRENT  

E-print Network

INSIDE UNL WATER CENTER WATER CURRENT PROTECTING NEBRASKA'S WATER RESOURCES THROUGH RESEARCH Researchers Honing Methods to Sample Field Run-off Water by Steve Ress The effectiveness of riparian buffer is important since many fertilizers and pesticides are designed to adhere to soil molecules. So if water

Nebraska-Lincoln, University of

220

Water, Water Everywhere  

NSDL National Science Digital Library

This lesson plan is part of the DiscoverySchool.com lesson plan library for grades 6-8. It focuses on data modules and students' understanding of the relationship between population growth and water shortages. Included are objectives, materials, procedures, discussion questions, evaluation ideas, suggested readings, and vocabulary. There are videos available to order which complement this lesson, an audio-enhanced vocabulary list, and links to teaching tools for making custom quizzes, worksheets, puzzles and lesson plans.

221

Ground Water and Drinking Water  

NSDL National Science Digital Library

The Environmental Protection Agencies Web site, Ground Water and Drinking Water (last mentioned in the March 29, 2002 Scout Report), has many additional high quality features not mentioned in previous reports. The site has continually updated information regarding drinking water regulation, as well as general facts such as where drinking water comes from, what's in it, drinking water standards, how you can protect your drinking water, a link for kids, and an extensive amount of additional material.

222

Stacking Water  

NSDL National Science Digital Library

In this lesson, students become familiar with how ocean water forms density-stratified layers in many places. They design and carry out a series of tests to show how water masses of four different densities interact, using clear straws to stack colored water of different salinities. Temperature is varied to increase the differences in density of each water sample.

223

WATER QUALITY  

EPA Science Inventory

Water quality is important not only because of its linkage to the availability of water for various uses and its impact on public health, but also because water quality has an intrinsic value. he quality of life is often judged on the availability of pristine water. ontamination ...

224

Water Conservation  

NSDL National Science Digital Library

In this lesson, students study the availability of water on Earth and discuss methods that can be used to purify and conserve this critical resource. Using multimedia interactives, video, and classroom activities, they will identify sources of fresh water available for consumption, understand the need for water conservation, and compare the benefits and drawbacks of different water management techniques. They will also assess how much water they and their families typically use, and think about ways to reduce their water usage. Finally, students explore different techniques being employed for water management around the world, including the use of dams to create reservoirs.

2005-01-01

225

Water Systems  

NSDL National Science Digital Library

Water cycle concepts and basics including the distribution of water on the planet in oceans, rivers and lakes, glaciers and atmosphere. Defines basic terms: states of water, evaporation, transpiration, condensation, precipitation, melting. Good illustrations, maps and photos. Excellent list itemizes human uses and impacts on water and the water cycle. Links to more detailed references are provided, case studies illustrate current concerns and issues in Ontario, Canada.

226

UNC EFRC: Fuels from Sunlight (A "Life at the Frontiers of Energy Research" contest entry from the 2011 Energy Frontier Research Centers (EFRCs) Summit and Forum)  

ScienceCinema

'Fuels from Sunlight' was submitted by the University of North Carolina (UNC) EFRC: Solar Fuels and Next Generation Photovoltaics to the 'Life at the Frontiers of Energy Research' video contest at the 2011 Science for Our Nation's Energy Future: Energy Frontier Research Centers (EFRCs) Summit and Forum. Twenty-six EFRCs created short videos to highlight their mission and their work. The UNC EFRC directed by Thomas J. Meyer is a partnership of scientists from six institutions: UNC (lead), Duke University, University of Florida, North Caroline Central University, North Carolina State University, and the Research Triangle Institute. The Office of Basic Energy Sciences in the U.S. Department of Energy's Office of Science established the 46 Energy Frontier Research Centers (EFRCs) in 2009. These collaboratively-organized centers conduct fundamental research focused on 'grand challenges' and use-inspired 'basic research needs' recently identified in major strategic planning efforts by the scientific community. The overall purpose is to accelerate scientific progress toward meeting the nation's critical energy challenges. The mission of Solar Fuels and Next Generation Photovoltaics is 'to combine the best features of academic and translational research to study light/matter interactions and chemical processes for the efficient collection, transfer, and conversion of solar energy into chemical fuels and electricity.' Research topics are: catalysis (CO{sub 2}, hydrocarbons, water), electrocatalysis, photocatalysis, photoelectrocatalysis, solar photovoltaic, solar fuels, photonic, solar electrodes, photosynthesis, fuel cells, CO{sub 2} (convert), greenhosue gas, hydrogen (fuel), interfacial characterization, novel materials synthesis, charge transport, and self-assembly.

Meyer, Thomas J. (Director, UNC EFRC: Solar Fuels and Next Generation Photovoltaics); UNC EFRC Staff

2011-11-02

227

Earth-Abundant Metal Pyrites (FeS2, CoS2, NiS2, and Their Alloys) for Highly Efficient Hydrogen Evolution and Polysulfide Reduction Electrocatalysis.  

PubMed

Many materials have been explored as potential hydrogen evolution reaction (HER) electrocatalysts to generate clean hydrogen fuel via water electrolysis, but none so far compete with the highly efficient and stable (but cost prohibitive) noble metals. Similarly, noble metals often excel as electrocatalytic counter electrode materials in regenerative liquid-junction photoelectrochemical solar cells, such as quantum dot-sensitized solar cells (QDSSCs) that employ the sulfide/polysulfide redox electrolyte as the hole mediator. Here, we systematically investigate thin films of the earth-abundant pyrite-phase transition metal disulfides (FeS2, CoS2, NiS2, and their alloys) as promising alternative electrocatalysts for both the HER and polysulfide reduction. Their electrocatalytic activity toward the HER is correlated to their composition and morphology. The emergent trends in their performance suggest that cobalt plays an important role in facilitating the HER, with CoS2 exhibiting highest overall performance. Additionally, we demonstrate the high activity of the transition metal pyrites toward polysulfide reduction and highlight the particularly high intrinsic activity of NiS2, which could enable improved QDSSC performance. Furthermore, structural disorder introduced by alloying different transition metal pyrites could increase their areal density of active sites for catalysis, leading to enhanced performance. PMID:25247028

Faber, Matthew S; Lukowski, Mark A; Ding, Qi; Kaiser, Nicholas S; Jin, Song

2014-09-18

228

Source Water Protection  

MedlinePLUS

... You are here: Water Water Infrastructure Ground Water & Drinking Water Source Water Source Water Protection Source Water Protection The drinking water we receive from our local drinking water utilities ...

229

Earth's Water:Ground Water  

NSDL National Science Digital Library

This USGS site contains graphs, tables, and charts for the following ground water topics: What is ground water, ground water flow diagrams, importance of groundwater, and trends in ground-water use. Ground water quality, pesticides, aquifers, waterwells, artesian wells, sinkholes, and land subsidence are also covered. There are a variety of links within all of the above topics and a very complete glossary, as well as numerous charts, maps, photographs and illustrations.

230

Water tight.  

PubMed

Many cities worldwide have gone beyond the limits of their water supply. Growing urban populations increase their demand for water, thereby straining local water supplies and requiring engineers to seek our even more distant water sources. It is costly to build and maintain reservoirs, canals, pumping stations, pipes, sewers, and treatment plants. Water supply activities require much energy and chemicals, thereby contributing to environmental pollution. Many cities are beginning to manage the water supply rather than trying to keep up with demand. Pumping ground water for Mexico City's 18 million residents (500,000 people added/year) surpasses natural replenishment by 50% to 80%, resulting in falling water tables and compressed aquifers. Mexico City now ambitiously promotes replacement of conventional toilets with 1.6 gallon toilets (by late 1991, this had saved almost 7.4 billion gallons of water/year). Continued high rural-urban migration and high birth rates could negate any savings, however. Waterloo, Ontario, has also used conservation efforts to manage water demand. These efforts include retrofit kits to make plumbing fixtures more efficient, efficiency standards for plumbing fixtures, and reduction of water use outdoors. San Jose, California, has distributed water savings devices to about 220,000 households with a 90% cooperation rate. Boston, Massachusetts, not only promoted water saving devices but also repaired leaks and had an information campaign. Increasing water rates to actually reflect true costs also leads to water conservation, but not all cities in developing countries use water meters. All households in Edmonton, Alberta, are metered and its water use is 1/2 of that of Calgary, where only some households are metered. Tucson, Arizona, reduced per capita water use 16% by raising water rates and curbing water use on hot days. Bogor, Indonesia, reduced water use almost 30% by increasing water rates. In the US, more and more states are mandating use of water-efficient plumbing fixtures. Multilateral development agencies have identified some developing country cities as demonstrated sites for urban water conservation. PMID:12286138

Postel, S

1993-01-01

231

Water Purifier  

NASA Technical Reports Server (NTRS)

The Floatron water purifier combines two space technologies - ionization for water purification and solar electric power generation. The water purification process involves introducing ionized minerals that kill microorganisms like algae and bacteria. The 12 inch unit floats in a pool while its solar panel collects sunlight that is converted to electricity. The resulting current energizes a specially alloyed mineral electrode below the waterline, causing release of metallic ions into the water. The electrode is the only part that needs replacing, and water purified by the system falls within EPA drinking water standards.

1992-01-01

232

Valuable water  

NASA Astrophysics Data System (ADS)

In some places, money flows with water. Studying both the water quality and property values around 22 lakes in south-central Maine, Kevin Boyle and Holly James of the University of Maine and Roy Bouchard of the Maine Department of Environmental Protection have found that good water quality makes waterfront property even more valuable. To gauge water quality, the researchers used Secchi disks to measure the clarity of the water at depth. They also reviewed 543 lakefront property sales between 1990 and 1994 to determine how values correlated with changing water conditions. The group also considered such factors as lake frontage, sizes of the houses and lots, and size of the lake.

Carlowicz, Michael

233

Branding water  

PubMed Central

Branding is a key strategy widely used in commercial marketing to make products more attractive to consumers. With the exception of bottled water, branding has largely not been adopted in the water context although public acceptance is critical to the implementation of water augmentation projects. Based on responses from 6247 study participants collected between 2009 and 2012, this study shows that (1) different kinds of water – specifically recycled water, desalinated water, tap water and rainwater from personal rainwater tanks – are each perceived very differently by the public, (2) external events out of the control of water managers, such as serious droughts or floods, had a minimal effect on people's perceptions of water, (3) perceptions of water were stable over time, and (4) certain water attributes are anticipated to be more effective to use in public communication campaigns aiming at increasing public acceptance for drinking purposes. The results from this study can be used by a diverse range of water stakeholders to increase public acceptance and adoption of water from alternative sources. PMID:24742528

Dolnicar, Sara; Hurlimann, Anna; Grün, Bettina

2014-01-01

234

Branding water.  

PubMed

Branding is a key strategy widely used in commercial marketing to make products more attractive to consumers. With the exception of bottled water, branding has largely not been adopted in the water context although public acceptance is critical to the implementation of water augmentation projects. Based on responses from 6247 study participants collected between 2009 and 2012, this study shows that (1) different kinds of water - specifically recycled water, desalinated water, tap water and rainwater from personal rainwater tanks - are each perceived very differently by the public, (2) external events out of the control of water managers, such as serious droughts or floods, had a minimal effect on people's perceptions of water, (3) perceptions of water were stable over time, and (4) certain water attributes are anticipated to be more effective to use in public communication campaigns aiming at increasing public acceptance for drinking purposes. The results from this study can be used by a diverse range of water stakeholders to increase public acceptance and adoption of water from alternative sources. PMID:24742528

Dolnicar, Sara; Hurlimann, Anna; Grün, Bettina

2014-06-15

235

Water Pollution  

ERIC Educational Resources Information Center

Deals with water pollution in the following categories: a global view, self purification, local pollution, difficulties in chemical analysis, and remedies for water pollution. Emphasizes the extent to which man's activities have modified the cycles of certain elements. (GS)

Bowen, H. J. M.

1975-01-01

236

Water Walk  

NSDL National Science Digital Library

Learners take a field trip along a local body of water and conduct a visual survey to discover information about local land use and water quality. Learners document their findings by mapping and profiling the water body. They can upload their measurements via the internet to a GLOBE scientist. Learners also use this initial investigation to raise questions about local land use and/or water quality issues that may require further study.

Isaacs, Beth

2009-01-01

237

Marketing water  

E-print Network

management, water conservation programs Story by Kathy Wythe tx H2O | pg. 17 public information programs and materials that increase awareness about regional water issues. The company recently opened the TecH2O, a water resource learning center... from the landscape property.) Dr. Don Wilkerson, AgriLife Extension horticulturist and one of the urban guide developers, said the guide targets three audiences?homeowners, horticulture profes- sionals, and municipal government and water utility...

Wythe, Kathy

2008-01-01

238

Water resources  

NASA Technical Reports Server (NTRS)

The application of ERTS-1 imagery to the conservation and control of water resources is discussed. The effects of exisiting geology and land use in the water shed area on the hydrologic cycle and the general characteristics of runoff are described. The effects of floods, snowcover, and glaciers are analyzed. The use of ERTS-1 imagery to map surface water and wetland areas to provide rapid inventorying over large regions of water bodies is reported.

Salomonson, V. V.; Rango, A.

1973-01-01

239

Falling Water  

NSDL National Science Digital Library

Students drop water from different heights to demonstrate the conversion of water's potential energy to kinetic energy. They see how varying the height from which water is dropped affects the splash size. They follow good experiment protocol, take measurements, calculate averages and graph results. In seeing how falling water can be used to do work, they also learn how this energy transformation figures into the engineering design and construction of hydroelectric power plants, dams and reservoirs.

Integrated Teaching And Learning Program

240

Water Cycle  

NSDL National Science Digital Library

Water Cycle fun From water cycle Web Quest Links Introduction Task Process Evaluation Conclusion Resources Teacher Guide Introduction Luke Warm, a weather man, and you will help two baseball players understand why the big game might be rained out. You will explore the Water cycle and ...

Mrs. Terry

2009-04-03

241

Water Resources  

NASA Technical Reports Server (NTRS)

Uses of ERTS-1 imagery and data for water resources surveys and management are summarized. Areas discussed are: (1) land use and geology; (2) flood plain and flood inundation mapping; (3) snow cover mapping; (4) glacier observations; (5) data collection systems; (6) surface waters; (7) wetlands mapping; (8) water quality; (9) soil mapping; (10) phreatophyte and riparian vegetation mapping; and (11) evapotranspiration.

Salomonson, V. V.

1973-01-01

242

Water purification  

Microsoft Academic Search

A system and method are described for removal of oil, sand, and other impurities from water. Water containing such impurities is moved at a very low velocity to allow heavy solid particles to drop out and light solid particles to float to the surface where they may be removed, the water then being passed through a filter wall which is

DeYoung

1971-01-01

243

Water Filtration  

NSDL National Science Digital Library

Students are asked to design methods to filter water using ordinary materials, while also considering their designs' material and cost efficiencies. They learn about the importance of water and its role in our everyday lives. They come to understand what must occur each day so that they can have clean water.

Center For Engineering Educational Outreach

244

Water Conservation  

NSDL National Science Digital Library

This activity was developed to get students thinking about the many ways that people use freshwater and how we can conserve this precious and fundamental natural resource. Students will watch a short documentary describing issues related to clean water availability, analyze water-use data and start to think about how they consume and can conserve water. This background knowledge will lead to students collecting data about their own water use and finding areas in their lives to conserve water. This activity uses the 5E instructional model and is part of the "Survivor Earth" series of one-hour lessons.

245

Water Conditioner  

NASA Technical Reports Server (NTRS)

The Aqualizer is designed to cleanse water with minimal use of chemicals by stabilizing the ions in the water. Its applications are both recreational and industrial. A non-electrical passive device, the Aqualizer operates on the principle of catalytic water conditioning. It consists of a stainless steel pipe length with a helical core and is offered in a variety of sizes depending on the quantity of water to be treated. The device is based on NASA silver ionization technology used to purify drinking water aboard the Apollo spacecraft.

1994-01-01

246

EXTENSION WATER SUMMIT PRIORITY: WATER CONSERVATION  

E-print Network

EXTENSION WATER SUMMIT PRIORITY: WATER CONSERVATION Leadership Team Subcommittee: Joan Bradshaw Michael Dukes Pierce Jones Kati Migliaccio #12;Water Conservation - Situation · Florida water supplies;Water Conservation Initiative 2: Enhancing and protecting water quality, quantity, and supply Priority 1

Kane, Andrew S.

247

Drinking Water and Ground Water: Kids' Stuff  

MedlinePLUS

... Kids Drinking Water & Ground Water Kids' Stuff Drinking Water & Ground Water Kids' Stuff Kids' Home Games & Activities Other Kids' ... to you. Submit Your Artwork from Thirstin's Wacky Water Adventure Activity Book Here Area Navigation Water Home ...

248

Water Markets and Water Quality  

Microsoft Academic Search

In addition to improving the allocative efficiency of water use, water markets may reduce irrigation-related water quality problems. This potential benefit is examined with a nonlinear programming model developed to simulate agricultural decision-making in a drainage problem area in California's San Joaquin Valley. Results indicate that a 30% drainage goal is achievable through improvements in irrigation practices and changes in

Catherine L. Kling; Marca Weinberg; James E. Wilen

1993-01-01

249

Thin-film fixed-bed reactor for solar photocatalytic inactivation of Aeromonas hydrophila: influence of water quality  

PubMed Central

Background Controlling fish disease is one of the major concerns in contemporary aquaculture. The use of antibiotics or chemical disinfection cannot provide a healthy aquaculture system without residual effects. Water quality is also important in determining the success or failure of fish production. Several solar photocatalytic reactors have been used to treat drinking water or waste water without leaving chemical residues. This study has investigated the impact of several key aspects of water quality on the inactivation of the pathogenic bacterium Aeromonas hydrophila using a pilot-scale thin-film fixed-bed reactor (TFFBR) system. Results The level of inactivation of Aeromonas hydrophila ATCC 35654 was determined using a TFFBR with a photocatalytic area of 0.47 m2 under the influence of various water quality variables (pH, conductivity, turbidity and colour) under high solar irradiance conditions (980–1100 W m-2), at a flow rate of 4.8 L h-1 through the reactor. Bacterial enumeration were obtained through conventional plate count using trypticase soy agar media, cultured in conventional aerobic conditions to detect healthy cells and under ROS-neutralised conditions to detect both healthy and sub-lethally injured (oxygen-sensitive) cells. The results showed that turbidity has a major influence on solar photocatalytic inactivation of A. hydrophila. Humic acids appear to decrease TiO2 effectiveness under full sunlight and reduce microbial inactivation. pH in the range 7–9 and salinity both have no major effect on the extent of photoinactivation or sub-lethal injury. Conclusions This study demonstrates the effectiveness of the TFFBR in the inactivation of Aeromonas hydrophila under the influence of several water quality variables at high solar irradiance, providing an opportunity for the application of solar photocatalysis in aquaculture systems, as long as turbidity remains low. PMID:23194331

2012-01-01

250

Ground Water Ground Sky Sky Water Vegetation Ground Vegetation Water  

E-print Network

Bear Snow Vegetation RhinoWater Vegetation Ground Water Ground Sky Sky Rhino Water Vegetation Ground Vegetation Water Rhino Water Vegetation Ground Rhino Water Rhino Water Ground Ground Vegetation Water Rhino Vegetation Rhino Vegetation Ground Rhino Vegetation Ground Sky Rhino Vegetation Ground Sky

Chen, Tsuhan

251

Water Resources  

E-print Network

Groundwater Group, and Ebasco Services, Inc. In addition, the following plans, studies and reports related to water resources are also available to be read at the Planning Department or at the Permit Center: Water Assessment For San Juan County, prepared by the Citizens Water Advisory Committee with assistance from the County Planning and Health & Community Services departments and the state Departments of Ecology and Health, was adopted by Board of County Commissioners

unknown authors

252

Water Animation  

NSDL National Science Digital Library

This Flash animation provides a detailed explanation of the chemistry and properties of water. Animated diagrams accompanied by written explanations show the configuration of the water molecule, how water molecules link together, what the crystal structure of ice looks like, and how acids and bases are formed. There is also an animated diagram of the pH scale showing the range in which most cellular processes occur and the approximate pH of some common substances. A French translation is available.

John Kyrk

253

Water Purifiers  

NASA Technical Reports Server (NTRS)

Technology developed to purify the water aboard manned spacecraft has led to a number of spinoff applications. One of them is the Ambassador line of bacteriostatic water treatment systems, which employ high grade, high absorption media to inhibit bacteria growth and remove the medicinal taste and odor of chlorine. Company President, Ray Ward, originally became interested in the technology because of the "rusty" taste of his water supply.

1992-01-01

254

Water Quality  

NSDL National Science Digital Library

In this online interactive, learners explore the various types of life that live in fresh water systems and how the presence of these organisms is an indication of the overall health of the water. Learners perform a water quality test that simulates tests performed in the field and use the data to determine the pollution level of three different streams. This activity also introduces learners to macroinvertebrates (animals without backbones).

Service, National P.

2011-08-20

255

Water Harvesting  

NSDL National Science Digital Library

This manual has been written with the intention of providing technicians and extension workers with practical guidelines on the implementation of water harvesting schemes. However it will also be of interest to a wider audience, such as rural development specialists and planners. The focus of the manual is on simple, field scale systems for improved production of crops, trees and rangeland species in drought prone areas. Water harvesting systems for water supply such as haffirs, ponds and rooftop tanks are not covered in this manual, nor are large-scale water spreading systems (spate irrigation).

Critchley, Will; Siegart, Klaus

2008-10-02

256

Water Filters  

NASA Technical Reports Server (NTRS)

The Aquaspace H2OME Guardian Water Filter, available through Western Water International, Inc., reduces lead in water supplies. The filter is mounted on the faucet and the filter cartridge is placed in the "dead space" between sink and wall. This filter is one of several new filtration devices using the Aquaspace compound filter media, which combines company developed and NASA technology. Aquaspace filters are used in industrial, commercial, residential, and recreational environments as well as by developing nations where water is highly contaminated.

1993-01-01

257

An overview on the advanced oxidation processes applied for the treatment of water pollutants defined in the recently launched Directive 2013/39/EU.  

PubMed

Environmental pollution is a recognized issue of major concern since a wide range of contaminants has been found in aquatic environment at ngL(-1) to ?gL(-1) levels. In the year 2000, a strategy was defined to identify the priority substances concerning aquatic ecosystems, followed by the definition of environmental quality standards (EQS) in 2008. Recently it was launched the Directive 2013/39/EU that updates the water framework policy highlighting the need to develop new water treatment technologies to deal with such problem. This review summarizes the data published in the last decade regarding the application of advanced oxidation processes (AOPs) to treat priority compounds and certain other pollutants defined in this Directive, excluding the inorganic species (cadmium, lead, mercury, nickel and their derivatives). The Directive 2013/39/EU includes several pesticides (aldrin, dichlorodiphenyltrichloroethane, dicofol, dieldrin, endrin, endosulfan, isodrin, heptachlor, lindane, pentachlorophenol, chlorpyrifos, chlorfenvinphos, dichlorvos, atrazine, simazine, terbutryn, diuron, isoproturon, trifluralin, cypermethrin, alachlor), solvents (dichloromethane, dichloroethane, trichloromethane and carbon tetrachloride), perfluorooctane sulfonic acid and its derivatives (PFOS), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), nonylphenol and octylphenol, as well as the three compounds included in the recommendation for the first watch list of substances (diclofenac, 17-alpha-ethinylestradiol (EE2) and 17-beta-estradiol (E2)). Some particular pesticides (aclonifen, bifenox, cybutryne, quinoxyfen), organotin compounds (tributyltin), dioxins and dioxin-like compounds, brominated diphenylethers, hexabromocyclododecanes and di(2-ethylhexyl)phthalate are also defined in this Directive, but studies dealing with AOPs are missing. AOPs are recognized tools to destroy recalcitrant compounds or, at least, to transform them into biodegradable species. Diuron (a phenylurea herbicide) and atrazine (from the triazine chemical class) are the most studied pesticides from Directive 2013/39/EU. Fenton-based processes are the most frequently applied to treat priority compounds in water and their efficiency typically increases with the operating temperature as well as under UV or solar light. Heterogeneous photocatalysis is the second most used treatment to destroy pollutants defined in the Directive. Ozone alone promotes the partial oxidation of pollutants, and an increase in the effluent biodegradability, but complete mineralization of pollutants is difficult. To overcome this drawback, ozonation has been combined with heterogeneous catalysts, addition of H2O2, other AOPs (such as photocatalysis) or membrane technologies. PMID:25461413

Ribeiro, Ana R; Nunes, Olga C; Pereira, Manuel F R; Silva, Adrián M T

2015-02-01

258

Water Science for Schools: USGS Water Information  

NSDL National Science Digital Library

This site offers information on many aspects of water, including text, pictures, data, maps, and an interactive center where users can offer opinions and test their water knowledge. Main topics include: water basics, Earth's water, water use, and special topics such as acid rain, saline water and other water-quality issues. Links to other water-related sites are also provided.

2001-07-02

259

Volcano plots in hydrogen electrocatalysis – uses and abuses  

PubMed Central

Summary Sabatier’s principle suggests, that for hydrogen evolution a plot of the rate constant versus the hydrogen adsorption energy should result in a volcano, and several such plots have been presented in the literature. A thorough examination of the data shows, that there is no volcano once the oxide-covered metals are left out. We examine the factors that govern the reaction rate in the light of our own theory and conclude, that Sabatier’s principle is only one of several factors that determine the rate. With the exception of nickel and cobalt, the reaction rate does not decrease for highly exothermic hydrogen adsorption as predicted, because the reaction passes through more suitable intermediate states. The case of nickel is given special attention; since it is a 3d metal, its orbitals are compact and the overlap with hydrogen is too low to make it a good catalyst. PMID:24991521

Quaino, Paola; Juarez, Fernanda; Santos, Elizabeth

2014-01-01

260

Electrocatalysis of fuel cell reactions: Investigation of alternate electrolytes  

NASA Technical Reports Server (NTRS)

Oxygen reduction and transport properties of the electrolyte in the phosphoric acid fuel cell are studied. A theoretical expression for the rotating ring-disk electrode technique; the intermediate reaction rate constants for oxygen reduction on platinum in phosphoric acid electrolyte; oxygen reduction mechanism in trifluoromethanesulfonic acid (TFMSA), considered as an alternate electrolyte for the acid fuel cells; and transport properties of the phosphoric acid electrolyte at high concentrations and temperatures are covered.

Chin, D. T.; Hsueh, K. L.; Chang, H. H.

1983-01-01

261

Microfluidic platforms and fundamental electrocatalysis studies for fuel cell applications  

NASA Astrophysics Data System (ADS)

The fabrication and testing of a planar membraneless microchannel fuel cell, based on a silicon microchannel, is described in detail. Laminar flow of fuel and oxidant streams, one on top of the other, prevents fuel crossover while allowing ionic transport at the interface between the two solutions. By employing laminar flow, the useful functions of a membrane are retained, while bypassing its inherent limitations. The planar design maximizes the anode and cathode areas, and elimination of the membrane affords broad flexibility in the choice of fuel and oxidant. Fuels including formic acid, methanol, ethanol, sodium borohydride and hydrogen were tested along with oxidants such as oxygen, hydrogen peroxide and potassium permanganate. Steps taken to improve voltage, current density, and overall power output have been addressed, including the testing of a dual electrolyte system and the use of micro-patterned electrode surfaces to enhance fuel utilization. As the complexity of the fuels studied in the microchannel fuel cell increased, it was imperative to characterize these fuels using electrochemical techniques prior to utilization in the fuel cell. The oxidation pathway of the liquid fuel methanol was studied rigorously because of its importance for micro-fuel cell applications. Activation energies for methanol oxidation at a Ptpoly surface were determined using electrochemical techniques, providing a benchmark for the comparison of activation energies of other Pt-based electrocatalysts for methanol oxidation at a given potential. A protocol to obtain Ea values was established in three different electrolytes and experimental parameters that influence the magnitude of these values are discussed in detail. The oxidation pathways of sodium borohydride were also examined at Au, Pt, and Pd surfaces using cyclic voltammetry, chronoamperometry, and rotating disk electrode voltammetry. In addition to studies on bulk Ptpoly surfaces, new bulk intermetallic catalysts were characterized for their electrocatalytic activity in formic acid. These intermetallics, including Pt2Ta, Pt3Ta, and PtTi, were compared to Pt in terms of onset of oxidation potential and current density at a given potential. The intermetallic PtPb was also extensively characterized in nine different fuels at room temperature, and at 70°C, and compared to Ptpoly.

Cohen, Jamie Lee

262

ELECTROCATALYSIS ON SURFACES MODIFIED BY METAL MONOLAYERS DEPOSITED AT UNDERPOTENTIALS.  

SciTech Connect

The remarkable catalytic properties of electrode surfaces modified by monolayer amounts of metal adatoms obtained by underpotential deposition (UPD) have been the subject of a large number of studies during the last couple of decades. This interest stems from the possibility of implementing strictly surface modifications of electrocatalysts in an elegant, well-controlled way, and these bi-metallic surfaces can serve as models for the design of new catalysts. In addition, some of these systems may have potential for practical applications. The UPD of metals, which in general involves the deposition of up to a monolayer of metal on a foreign substrate at potentials positive to the reversible thermodynamic potential, facilitates this type of surface modification, which can be performed repeatedly by potential control. Recent studies of these surfaces and their catalytic properties by new in situ surface structure sensitive techniques have greatly improved the understanding of these systems.

ADZIC,R.

2000-12-01

263

Electrocatalysis of fuel cell reactions: Investigation of alternate electrolytes  

NASA Technical Reports Server (NTRS)

Oxygen reduction and transport properties of the electrolyte in the phosphoric acid fuel cell are studied. The areas covered were: (1) development of a theoretical expression for the rotating ring disk electrode technique; (2) determination of the intermediate reaction rate constants for oxygen reduction on platinum in phosphoric acid electrolyte; (3) determination of oxygen reduction mechanism in trifluoreomethanesulfonic acid (TFMSA) which was considered as an alternate electrolyte for the acid fuel cells; and (4) the measurement of transport properties of the phosphoric acid electrolyte at high concentrations and temperatures.

Chin, D. T.; Hsueh, K. L.; Chang, H. H.

1984-01-01

264

Characterizing nano-scale electrocatalysis during partial oxidation of methane  

PubMed Central

Electrochemical analysis allows in situ characterization of solid oxide electrochemical cells (SOCs) under operating conditions. However, the SOCs that have been analyzed in this way have ill-defined or uncommon microstructures in terms of porosity and tortuosity. Therefore, the nano-scale characterization of SOCs with respect to three-phase boundaries has been hindered. We introduce novel in situ electrochemical analysis for SOCs that uses combined solid electrolyte potentiometry (SEP) and impedance measurements. This method is employed to investigate the oscillatory behavior of a porous Ni-yttria-stabilized zirconia (YSZ) anode during the partial oxidation of methane under ambient pressure at 800°C. The cyclic oxidation and reduction of nickel induces the oscillatory behavior in the impedance and electrode potential. The in situ characterization of the nickel surface suggests that the oxidation of the nickel occurs predominantly at the two-phase boundaries, whereas the nickel at the three-phase boundaries remains in the metallic state during the cyclic redox reaction. PMID:24487242

Lee, Daehee; Kim, Dongha; Kim, Joosun; Moon, Jooho

2014-01-01

265

Perovskite-type oxides - Oxygen electrocatalysis and bulk structure  

NASA Technical Reports Server (NTRS)

Perovskite type oxides were considered for use as oxygen reduction and generation electrocatalysts in alkaline electrolytes. Perovskite stability and electrocatalytic activity are studied along with possible relationships of the latter with the bulk solid state properties. A series of compounds of the type LaFe(x)Ni1(-x)O3 was used as a model system to gain information on the possible relationships between surface catalytic activity and bulk structure. Hydrogen peroxide decomposition rate constants were measured for these compounds. Ex situ Mossbauer effect spectroscopy (MES), and magnetic susceptibility measurements were used to study the solid state properties. X ray photoelectron spectroscopy (XPS) was used to examine the surface. MES has indicated the presence of a paramagnetic to magnetically ordered phase transition for values of x between 0.4 and 0.5. A correlation was found between the values of the MES isomer shift and the catalytic activity for peroxide decomposition. Thus, the catalytic activity can be correlated to the d-electron density for the transition metal cations.

Carbonio, R. E.; Fierro, C.; Tryk, D.; Scherson, D.; Yeager, E.

1988-01-01

266

Water snails  

NSDL National Science Digital Library

Water snails have a shell for protection. They have two tentacles, a foot, and a head and a tail region. Water snails have eyes at the base of their sensory stalks. The stalks are used to smell and feel around the snail's environment.

Scott Bauer (USDA; ARS)

2005-08-03

267

WATER EROSION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Water erosion is caused by the detachment and transport of soil by runoff, melting snow or ice, and irrigation. Excessive erosion could threaten the production of agricultural and forest products. Erosion may also impact water conveyance and storage structures, and contribute to pollution from land ...

268

Drinking Water  

EPA Science Inventory

This encyclopedic entry deals with various aspects of microbiology as it relates to drinking water treatment. The use of microbial indicators for assessing fecal contamination is discussed as well as current national drinking water regulations (U.S. EPA) and guidelines proposed ...

269

Virginia's Waters.  

ERIC Educational Resources Information Center

This booklet describes the water resources in Virginia. Main sections included are: (1) "Introduction" (providing a general overview of the richness and diversity of Virginia's water resources both economic and recreational); (2) "River Basins" (illustrating the area drained by nine rivers and their tributaries); (3) "Bays" (including the…

Sevebeck, Kathryn P.; And Others

270

Water characteristics  

Microsoft Academic Search

Recent research on water characteristics is cited in this review article. Acid precipitation has been noted as one of the major environmental problems of the current decade. It poses a serious challenge to national and international bodies to protect water quality. Considerable interest was voiced in 1980 over the causes and effects, prevention and control of acid rain. One study

1981-01-01

271

Water Pollution  

MedlinePLUS

We all need clean water. People need it to grow crops and to operate factories, and for drinking and recreation. Fish and wildlife depend on ... and phosphorus make algae grow and can turn water green. Bacteria, often from sewage spills, can pollute ...

272

Water Filter  

NSDL National Science Digital Library

In this engineering activity, challenge learners to invent a water filter that cleans dirty water. Learners construct a filter device out of a 2-liter bottle and then experiment with different materials like gravel, sand, and cotton balls to see which is the most effective. Safety note: An adult's help is needed for this activity.

Boston, Wgbh

2002-01-01

273

Incorporation of Water-Oxidation Catalysts into Photoinduced Electron Transfer Systems: Toward Solar Fuel Generation via Artificial Photosynthesis  

NASA Astrophysics Data System (ADS)

A key goal of artificial photosynthesis is to mimic the photochemistry of photosystem II and oxidize water using light energy, with the ultimate aim of using the liberated electrons for reductive, fuel-forming reactions. One of the more recent challenges in the field of solar fuels chemistry is the efficient activation of molecular water-oxidation catalysts with photoinduced electron transfer, an effort that would benefit from detailed knowledge of the energetics and kinetics of each electron transfer step in a light-driven catalytic cycle. The focus of this thesis is the synthesis and photophysical characterization of covalent assemblies comprising a redox-active organic chromophore and the iridium(III)-based water-oxidation catalyst Cp*Ir(ppy)Cl (ppy = 2-phenylpyridine), and the rates and pathways for photogeneration of higher-valence states of the catalyst are determined with femtosecond transient absorption spectroscopy and other time-resolved spectroscopic techniques. In linking the photooxidant perylene-3,4:9,10-bis (dicarboximide) (PDI) to the Ir(III) catalyst, fast photoinduced electron transfer from the metal complex to PDI outcompetes heavy-atom quenching of the dye excited state, and the catalytic integrity of the complex is retained, as determined by electrocatalysis experiments. Long-lived higher-valence states of the catalyst are necessary for the accumulation of oxidizing equivalents for oxygen evolution, and the lifetime of photogenerated Ir(IV) has been extended by over two orders of magnitude by catalyst incorporation into a covalent electron acceptor--chromophore--catalyst triad, in which the dye is perylene-3,4-dicarboximide (PMI). Time resolved X-ray absorption studies of the triad confirm the photogeneration of an Ir(IV) metal center, a species that is too unstable to observe with chemical or electrochemical oxidation methods. This approach to preparing higher-valence states of water-oxidation catalysts has great promise for deducing catalytic mechanisms and probing highly-reactive intermediates, and it also establishes a basis in systems design for photodriving catalytic processes. Covalent dye-catalyst assemblies have been gaining recognition as a useful motif for incorporation into dye-sensitized photoanodes for photoelectrochemical water-splitting cells, and the PMI-Ir catalyst unit is well-poised, both in the energetics and kinetics of its electron transfer properties, to improve upon current solar-driven fuel-forming devices.

Vagnini, Michael Thomas

274

Ground water. [Water pollution control  

Microsoft Academic Search

There is growing evidence that the Nation's ground water is contaminated by a variety of sources. These include unprotected industrial, municipal, and radioactive disposal sites, petroleum exploration and mining activities, agricultural operations such as insecticide spraying, high de-icing salts and others. As of March 1980, more than 8000 chemical tests have been performed on well water, with chlorinated organic solvents

Costle

1980-01-01

275

Water 1: Water and Ice  

NSDL National Science Digital Library

In this lesson, students will explore what happens to water as it goes from solid to liquid and back again; in addition, they will use observation, measurement, and communication skills to describe change. This lesson is the first in a three-part series that addresses a concept that is central to the understanding of the water cycle: that water is able to take many forms but is still water. This series of lessons is designed to prepare students to understand that most substances may exist as solids, liquids, or gases depending on the temperature, pressure, and nature of that substance. This knowledge is critical to understanding that water in our world is constantly cycling as a solid, liquid, or gas.

276

Water Purification  

NASA Technical Reports Server (NTRS)

The Vision Catalyst Purifier employs the basic technology developed by NASA to purify water aboard the Apollo spacecraft. However, it also uses an "erosion" technique. The purifier kills bacteria, viruses, and algae by "catalytic corrosion." A cartridge contains a silver-impregnated alumina bed with a large surface area. The catalyst bed converts oxygen in a pool of water to its most oxidative state, killing over 99 percent of the bacteria within five seconds. The cartridge also releases into the pool low levels of ionic silver and copper through a controlled process of erosion. Because the water becomes electrochemically active, no electricity is required.

1994-01-01

277

Fragile Waters  

NSDL National Science Digital Library

In this activity (on pages 18-29) learners explore the impact of the March 24, 1989 oil spill in Alaska caused by the Exxon Valdez tanker. First they use a map to track the movement of the spill over 56 days. Learners then explore how oil behaves in water by examining the relative weight of water vs. oil, and the properties of oil. They test how oil damages various natural materials such as bird feathers, fur fabric, plants, shells, and rocks, and then try water and detergent to see which cleaning methods work best.

Museum, University O.

2014-01-28

278

Montana Water  

NSDL National Science Digital Library

Provided by the Montana University System Water Center at Montana State University-Bozeman, this impressive site offers a wealth of information regarding issues related to water in Montana and nationally. A mix of political (regarding recent legislation), educational, research, and funding/employment "water information" is posted at this Website, under several section headings: Information, Featured Programs, Policy & Legislation, Learning Resources, and Montana Watersheds. In addition, a substantial collection of links to related organizations and resources assists users in finding further online information.

279

Grabbing Water  

E-print Network

We introduce a novel technique for grabbing water with a flexible solid. This new passive pipetting mechanism was inspired by floating flowers and relies purely on the coupling of the elasticity of thin plates and the ...

Reis, Pedro Miguel

280

Water Privatisation   

E-print Network

This dissertation deals with the policy issues of large-scale, urban water privatisation projects in the face of uncertainty and variability. The main objective is to evaluate whether a single policy approach, namely privatisation associated...

Zölls, Elisa

2011-08-17

281

WATER ANALYSIS  

EPA Science Inventory

This review covers developments in water analysis from November 1996 to the end of October 1998, as found in the Chemical Abstracts Service CA Selects for gas chromatography, mass spectrometry, inorganic analytical chemistry, and pollution monitoring. In addition, because develop...

282

Water Fountain  

NSDL National Science Digital Library

In this activity, learners explore how a hydraulic pump works. Learners work in teams to design and build a unique water fountain that employs a hydraulic pump. This lesson also contains a demonstration of a hydraulic pump in action.

2014-05-22

283

Sinking Water  

NSDL National Science Digital Library

This experiment uses colored ice cubes to demonstrate how temperature changes water density. Working together in small groups, students can complete the experiment in a single class period. The printable eight-page handout includes a series of inquiry-based questions to get students thinking about how and why water temperature changes along with depth, illustrated experiment directions, and a worksheet that helps students use the experiment results to gain a deeper understanding of buoyancy and density.

284

Sinking Water  

NSDL National Science Digital Library

This experiment uses colored ice cubes to demonstrate how temperature changes water density. Working together in small groups, students can complete the experiment in a single class period. The printable eight-page handout includes a series of inquiry-based questions to get students thinking about how and why water temperature changes along with depth. There are illustrated experiment directions, and a worksheet that helps students use the experiment results to gain a deeper understanding of buoyancy and density.

285

Water quality.  

USGS Publications Warehouse

Significant contributions in the broad area of water quality over the quadrennium 1975-78 are highlighted. This summare is concerned primarily with physical and chemical aspects of water quality. The diversity of subject areas within the topic heading and the large volume of published research results necessitated the selection of representative contributions. Over 400 references are cited which are believed to be indicative of general trends in research and of the more important developments during this period.- from Authors

Steele, T.D.; Stefan, H.G.

1979-01-01

286

Water Walk  

NSDL National Science Digital Library

The purpose of this resource is to become familiar with the hydrology of your locale. Students will study and visit the Hydrology Study Site, conduct a visual survey to discover information about local land cover, water quality, and document their findings. They will use this initial investigation to raise questions about local land cover and/or water chemistry issues that may require further investigation.

The GLOBE Program, UCAR (University Corporation for Atmospheric Research)

2003-08-01

287

Extraterrestrial Water  

NASA Astrophysics Data System (ADS)

Life as we know it, i.e., carbon-based organisms that rely on RNA and DNA for information storage and transfer, requires liquid water. Thus, the search for life elsewhere in the universe generally begins with a search for liquid water. In our own Solar System, Earth is the only planet (or moon) that has liquid water at its surface. Mars and Europa both probably have subsurface water. Researchers from NASA and elsewhere are hoping to eventually probe these subsurface reservoirs and determine whether life exists there. A more promising venue for finding extraterrestrial life is on Earth-like planets around other stars. Such planets can in principle be located and analyzed spectroscopically using large space-based telescopes like NASA's proposed Terrestrial Planet Finder (TPF) Mission (1). The chances of success for this mission depend critically on the abundance of Earth-like planets with liquid water at their surfaces because only there could a biota exist that would be widespread enough to modify the planet's atmosphere in a way that would be detectable. Models of planetary accretion suggest that most terrestrial planets should be endowed with substantial amounts of water (2). Climate models suggest that the "habitable zone" around solar-type stars is relatively wide so that water can remain liquid on a planet's surface for long times (3). Thus, the chances of finding water, and maybe life, elsewhere appear to be good. References: (1) Beichman, C. A., Woolf, N. J. and Lindensmith, C. A. The Terrestrial Planet Finder (TPF): A NASA Origins Program to Search for Habitable Planets (JPL Publication 99-3) (NASA Jet Propulsion Laboratory, Pasadena, CA, 1999). (2) Morbidelli, A., Chambers, J., Lunine, J. I., Petit, J. M., Robert, F., Valsecchi, G. B. and Cyr, K. E. Meteoritics and Planet. Sci. 35, 1309-1320 (2000). (3) Kasting, J. F., Whitmire, D. P. and Reynolds, R. T. Icarus 101, 108-128 (1993).

Kasting, J. F.

2002-12-01

288

Photocatalytic degradation of methyl orange dye in water solutions in the presence of MWCNT/TiO{sub 2} composites  

SciTech Connect

Highlights: ? MWCNTs/TiO{sub 2} composites were obtained to degrade organic dyes in water. ? MWCNT/TiO{sub 2} composites were analyzed by photocatalysis and structural characterization. ? The photocatalytic shows efficient method for the degradation of dyes from aqueous effluents. - Abstract: The textile and dyestuff industries are the primary sources of the release of synthetic dyes into the environment and usually there are major pollutants in dye wastewaters. Because of their toxicity and slow degradation, these dyes are categorized as environmentally hazardous materials. In this context, carbon nanotubes/TiO{sub 2} (CNTs/TiO{sub 2}) composites were prepared using multi-walled CNTs (MWCNTs), titanium (IV) propoxide and commercial TiO{sub 2} (P25{sup ®}) as titanium oxide sources, to degrade the methyl orange dye in solution through photocatalyst activity using UV irradiation. The composites were prepared by solution processing followed by thermal treatment at 400, 500 and 600 °C. The heterojunction between nanotubes and TiO{sub 2} was confirmed by XRD, specific surface area. The coating morphology was observed with SEM and TEM.

Da Dalt, S., E-mail: silvana.da.dalt@ufrgs.br [Department of Material, Federal University of Rio Grande do Sul, Av. Osvaldo Aranha 99, Laboratory 705C, ZIP 90035-190, Porto Alegre, RS (Brazil); Alves, A.K.; Bergmann, C.P. [Department of Material, Federal University of Rio Grande do Sul, Av. Osvaldo Aranha 99, Laboratory 705C, ZIP 90035-190, Porto Alegre, RS (Brazil)

2013-05-15

289

Total Water Management - slides  

EPA Science Inventory

Total Water Management (TWM) examines urban water systems in an interconnected manner. It encompasses reducing water demands, increasing water recycling and reuse, creating water supply assets from stormwater management, matching water quality to end-use needs, and achieving envi...

290

Water Resources Georgia  

NSDL National Science Digital Library

Water Resources Georgia: From the USGS web site comes the Georgia Water Information Network (GWIN)which offers water information for thousands of surface-water, ground-water, and water-quality measurement sites in Georgia.

291

Alignment of electronic energy levels at electrochemical interfaces.  

PubMed

The position of electronic energy levels in a phase depends on the surface potentials at its boundaries. Bringing two phases in contact at an interface will alter the surface potentials shifting the energy levels relative to each other. Calculating such shifts for electrochemical interfaces requires a combination of methods from computational surface science and physical chemistry. The problem is closely related to the computation of potentials of electrochemically inactive electrodes. These so-called ideally polarizable interfaces are impossible to cross for electrons. In this perspective we review two density functional theory based methods that have been developed for this purpose, the workfunction method and the hydrogen insertion method. The key expressions of the two methods are derived from the formal theory of absolute electrode potentials. As an illustration of the workfunction method we review the computation of the potential of zero charge of the Pt(111)-water interface as recently published by a number of groups. The example of the hydrogen insertion method is from our own work on the rutile TiO(2)(110)-water interface at the point of zero proton charge. The calculations are summarized in level diagrams aligning the electronic energy levels of the solid electrode (Fermi level of the metal, valence band maximum and conduction band minimum of the semiconductor) to the band edges of liquid water and the standard potential for the reduction of the hydroxyl radical. All potentials are calculated at the same level of density functional theory using the standard hydrogen electrode as common energy reference. Comparison to experiment identifies the treatment of the valence band of water as a potentially dangerous source of error for application to electrocatalysis and photocatalysis. PMID:22806244

Cheng, Jun; Sprik, Michiel

2012-08-28

292

Special Topics in Water Science (Water Pollution)  

MedlinePLUS

... A Teachers Contact Back to previous page Special Topics in Water Science Our Special Topics section lets you explore other water-science topic areas, such as water quality, urbanization and water, ...

293

Arnold Schwarzenegger WATER HEATERS AND HOT WATER  

E-print Network

Arnold Schwarzenegger Governor WATER HEATERS AND HOT WATER DISTRIBUTION SYSTEMS;#12;Appendices Appendix A. Multifamily Water Heating Construction Practices, Pricing and Availability Survey Report Appendix B. Multifamily Water Heating Controls Performance Field Report Appendix C. Pipe

294

Water Detectives  

NSDL National Science Digital Library

In this introductory classroom activity, students exercise their scientific skills of observation and deduction as they use their senses and simple laboratory assays, such as pH indicator paper, to identify mystery pollutants in water samples. Activity includes a student worksheet. This is a learning activity within the Hydrology chapter, GLOBE Teacher's Guide.

2012-08-03

295

Water Hyacinth  

Technology Transfer Automated Retrieval System (TEKTRAN)

An important new reference book entitled the “Encyclopedia of Invasive Introduced Species” is being published by the University of California Press. We were invited to provide a chapter on water hyacinth, which is the world’s worst aquatic weed. In this chapter, we provide information on the origi...

296

Grabbing water  

E-print Network

We introduce a novel technique for grabbing water with a flexible solid. This new passive pipetting mechanism was inspired by floating flowers and relies purely on the coupling of the elasticity of thin plates and the hydrodynamic forces at the liquid interface. Developing a theoretical model has enabled us to design petal-shaped objects with maximum grabbing capacity.

P. M. Reis; J. Hure; S. Jung; J. W. M. Bush; C. Clanet

2012-07-16

297

Water Quality  

NSDL National Science Digital Library

In this problem-based learning module, students work in teams to examine a broad array of information related to water quality in Lower Wheeling Creek and the Wheeling Creek watersheds in Wheeling, West Virginia. This module is part of Exploring the Environment.

298

Weightless Water  

NSDL National Science Digital Library

In this physics activity (page 5 of the PDF), learners will witness the effects of free fall by observing falling water, and will gain a better understanding of the concept of weightlessness. Although this activity was created as a post-visit for a workshop about astronomy, it also makes an excellent stand alone activity!

Cosi

2009-01-01

299

Troubling Waters  

NSDL National Science Digital Library

One of the world's richest deltas has been radically replumbed, its ecosystem is collapsing, and Californians are realizing their water supply is tapped out. Despite decades of efforts--and some positive trends--solutions may not be any closer. Downstream, the San Francisco Bay looks good by comparison.

Carolyn J. Strange (freelance writer;)

2008-12-01

300

Water world  

Microsoft Academic Search

We reproduced a beautiful sea and animals in the ocean by the latest software technology. They show their life in the great water world. Wave, splash, bubble and all fluid movement were created by our original fluid simulator to bling realistic and correct expression. In the beautiful ocean, dolphins, whale sharks, great white sharks, humpback whales and other beautiful animals

Makoto Chiba

2010-01-01

301

Contaminated Sediments in Water  

MedlinePLUS

... Contact Us Water: Contaminated Sediments You are here: Water Pollution Prevention & Control Sediments Contaminated Sediments in Water Contaminated ... Water Education & Training Grants & Funding Laws & Regulations Our Waters Pollution Prevention & Control Applications & Databases Low Impact Development Impaired ...

302

UNL WATER CENTER WATER CURRENT  

E-print Network

........SPECIAL BUREAU OF RECLAMATION CENTENNIAL COVERAGE 14..............Water News Briefs 15 Keyes, Commissioner of Reclamation, U.S. Bureau of Reclamation. Several con- vention topics will focus in the teens or 1920's. Exact date unknown U.S. Bureau of Reclamation projects to "reclaim" the arid western

Nebraska-Lincoln, University of

303

Water Striders  

NSDL National Science Digital Library

In this outdoor activity/field trip, learners catch and observe water striders to explore their movement and feeding behaviors. To observe strider locomotion, learners look closely at caught water striders' body structure, then mark the striders' bodies with a dot of thick tempera or acrylic paint and release the insects back to different areas of the pond habitat. The paint markings make it easier for learners to watch each insect's movement. To observe strider feeding, learners catch other small insects from the pond habitat and offer them to caught striders. After the activity, all organisms should be released into the pond habitat. If possible, learners can return to the strider habitat a few weeks after the activity, to check how far the marked striders have moved from where they were released.

Science, Lawrence H.

1981-01-01

304

Water Pollution  

NSDL National Science Digital Library

This set of activities is designed to help students understand water pollution and its potential effects on human and wildlife habitats. They will understand that pollutants can be divided into three groups: chemical, thermal, and biological. Learning objectives include identification of two or more pollutants in a bog, marsh, stream or other wetland area, using words and art to relate a message about pollution, and understanding that some pollutants cannot be seen.

305

Water resources data, Louisiana, water year 2004  

USGS Publications Warehouse

Water resources data for the 2004 water year for Louisiana consist of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; and water levels and water quality of ground water. This report contains records for water discharge at 77 gaging stations; stage only for 86 gaging stations and 7 lakes; water quality for 60 surface-water stations (including 42 gaging stations) and 112 wells; and water levels for 304 observation wells. Also included are data for 158 crest-stage and flood-profile partial-record stations. Additional water data were collected at various sites not included in the systematic data-collection program, and are published as miscellaneous measurements. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in Louisiana.

Baumann, Todd; Goree, B.B.; Lovelace, W.M.; Montogmery, P.A.; Resweber, J.C.; Ross, Garron B.; Ward, Aub N.; Walters, David J.

2005-01-01

306

Water Resources Data, Louisiana, Water Year 2000  

USGS Publications Warehouse

Water resources data for the 2000 water year for Louisiana consists of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; and water levels and water quality of ground water. This report contains records for water discharge at 66 gaging stations; stage only for 70 gaging stations and 7 lakes; water quality for 45 surface-water stations (including 25 gaging stations) and 108 wells; and water levels for 221 observation wells. Also included are data for 204 crest-stage and flood-profile partial-record stations. Additional water data were collected at various sites not included in the systematic data-collection program, and are published as miscellaneous measurements. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in Louisiana.

Goree, B.B.; Lovelace, W.M.; Montgomery, P.A.; Resweber, J.C.; Sasser, D.C., Jr.; Walters, David J.

2001-01-01

307

Water Resources Data, Louisiana, Water Year 2001  

USGS Publications Warehouse

Water resources data for the 2001 water year for Louisiana consists of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; and water levels and water quality of ground water. This report contains records for water discharge at 71 gaging stations; stage only for 73 gaging stations and 7 lakes; water quality for 66 surface-water stations (including 39 gaging stations) and 92 wells; and water levels for 205 observation wells. Also included are data for 166 crest-stage and flood-profile partial-record stations. Additional water data were collected at various sites not included in the systematic data-collection program, and are published as miscellaneous measurements. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in Louisiana.

Goree, B.B.; Lovelace, W.M.; Montgomery, P.A.; Resweber, J.C.; Sasser, D.C., Jr.; Walters, David J.

2002-01-01

308

Water resources data, Louisiana, water year 2003  

USGS Publications Warehouse

Water resources data for the 2003 water year for Louisiana consist of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; and water levels and water quality of ground water. This report contains records for water discharge at 76 gaging stations; stage only for 86 gaging stations and 7 lakes; water quality for 56 surface-water stations (including 44 gaging stations) and 142 wells; and water levels for 313 observation wells. Also included are data for 158 crest-stage and flood-profile partial-record stations. Additional water data were collected at various sites not included in the systematic data-collection program, and are published as miscellaneous measurements. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating Federal and State agencies in Louisiana.

Baumann, Todd; Goree, B.B.; Lovelace, W.M.; Montgomery, P.A.; Resweber, J.C.; Ross, Garron B.; Sasser, D.C., Jr.; Walters, D.J.

2004-01-01

309

Water Resources Data, Louisiana, Water Year 2002  

USGS Publications Warehouse

Water resources data for the 2002 water year for Louisiana consists of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; and water levels and water quality of ground water. This report contains records for water discharge at 85 gaging stations; stage only for 79 gaging stations and 7 lakes; water quality for 52 surface-water stations (including 40 gaging stations) and 104 wells; and water levels for 300 observation wells. Also included are data for 143 crest-stage and flood-profile partial-record stations. Additional water data were collected at various sites not included in the systematic data-collection program, and are published as miscellaneous measurements. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in Louisiana.

Goree, B.B.; Lovelace, W.M.; Montgomery, P.A.; Resweber, J.C.; Labbe, Charles K.; Walters, David J.

2003-01-01

310

Water Sustainability Program Challenges to Sustainable Water  

E-print Network

Water Sustainability Program Forum Challenges to Sustainable Water Management in Arizona Sharon B. Megdal Director, WSP & Water Resources Research Center November 22, 2010 smegdal@cals.arizona.edu #12;· The Water Sustainability Program endeavors to ensure that we have safe and reliable water supplies

Cushing, Jim. M.

311

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE  

E-print Network

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE 212 AGRICULTURAL ENGINEERING BUILDING Committee on Natioha1 Water Resources report in 1961 and the formation of the Committee on Water Resources in emphasis"and values regarding water resources' research. Interest has shifted from}J4ter supply

Nebraska-Lincoln, University of

312

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE  

E-print Network

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE 212 AGRICULTURAL ENGINEERING BUILDING.ROGRAM FOR THE 1972, I~TERDISCIPL1NARY SEMINAR ON WATER RESOURCES1 The Interdisciplinary Water Resources Seminar upper classmen,graduate stUdents, ~rofessiona1 persons, faculty, nd others interested 1n water topics

Nebraska-Lincoln, University of

313

Water Withdrawals and Water Use in Michigan  

E-print Network

Page 1 Water Withdrawals and Water Use in Michigan Michigan State University · New · February 2011 information about the amount of water used in Michigan and the purposes of its use is important for effective water resource management. Understanding water use by different sectors can help with planning

314

Water Wise: A Water Use Handbook.  

ERIC Educational Resources Information Center

This guide for elementary school students deals with the importance of and the uses of water, especially in the western United States. Topics covered include the importance of water as a resource; the need for conservation; water storage through dams and reservoirs; irrigation; the lack of water in the old West; the uses of water for cities and…

Bureau of Reclamation (Dept. of Interior), Washington, DC.

315

Ground water provides drinking water, irrigation for  

E-print Network

Ground water provides drinking water, irrigation for crops and water for indus- tries. It is also connected to surface waters, and maintains the flow of rivers and streams and the level of wetlands- tion of those along Lake Michigan, most communi- ties, farms and industries still rely on ground water

Saldin, Dilano

316

Water, Ohio's Remarkable Resource.  

ERIC Educational Resources Information Center

Information on water and water resources in Ohio is presented in seven sections. Water from Ohio streams, water storage, lakes in Ohio, and ground water are discussed in the first section ("Water, A Part of the Earth"). A brief discussion on the ecosystem is provided in the second section ("Water and Life"). Topics discussed in the third section…

Groves, Carrie J.

317

Be Water Wise.  

ERIC Educational Resources Information Center

Various topics on water and water conservation are discussed, each general topic followed by a student activity. Topics include: (1) importance of water; (2) water in the environment; (3) getting water to and from homes (making water usable; treating wastewater; on-site systems, including water wells and septic tanks); (4) relationship between…

Birch, Sandra K.; Pettus, Alvin M.

318

Visible Light Responsive Catalysts Using Quantum Dot-Modified Ti02 for Air and Water Purification  

NASA Technical Reports Server (NTRS)

The method of photocatalysis utilizing titanium dioxide, TiO2, as the catalyst has been widely studied for trace contaminant control for both air and water applications because of its low energy consumption and use of a regenerable catalyst. Titanium dioxide requires ultraviolet light for activation due to its band gap energy of 3.2 eV. Traditionally, Hg-vapor fluorescent light sources are used in PCO reactors and are a setback for the technology for space application due to the possibility of Hg contamination. The development of a visible light responsive (VLR) TiO2-based catalyst could lead to the use of solar energy in the visible region (approx.45% of the solar spectrum lies in the visible region; > 400 nm) or highly efficient LEDs (with wavelengths > 400 nm) to make PCO approaches more efficient, economical, and safe. Though VLR catalyst development has been an active area of research for the past two decades, there are few commercially available VLR catalysts; those that are available still have poor activity in the visible region compared to that in the UV region. Thus, this study was aimed at the further development of VLR catalysts by a new method - coupling of quantum dots (QD) of a narrow band gap semiconductor (e.g., CdS, CdSe, PbS, ZnSe, etc.) to the TiO2 by two preparation methods: 1) photodeposition and 2) mechanical alloying using a high-speed ball mill. A library of catalysts was developed and screened for gas and aqueous phase applications, using ethanol and 4-chlorophenol as the target contaminants, respectively. Both target compounds are well studied in photocatalytic systems serve as model contaminants for this research. Synthesized catalysts were compared in terms of preparation method, type of quantum dots, and dosage of quantum dots.

Coutts, Janelle L.; Levine, Lanfang H.; Richards, Jeffrey T.; Hintze, paul; Clausen, Christian

2012-01-01

319

Water Purification  

NASA Technical Reports Server (NTRS)

Silver ionization water purification technology was originally developed for Apollo spacecraft. It was later used to cleanse swimming pools and has now been applied to industrial cooling towers and process coolers. Sensible Technologies, Inc. has added two other technologies to the system, which occupies only six square feet. It is manufactured in three capacities, and larger models are custom built on request. The system eliminates scale, corrosion, algae, bacteria and debris, and because of the NASA technology, viruses and waterborne bacteria are also destroyed. Applications include a General Motors cooling tower, amusement parks, ice manufacture and a closed-loop process cooling system.

1992-01-01

320

SOURCE WATER ASSESSMENT GUIDANCE  

EPA Science Inventory

Provides guidance to primacy agencies and public water systems (PWS) for implementation of assessments of hydrogeologic sensitivity and source water fecal contamination under the Ground Water Rule (GWR)....

321

Environment Canada: Water  

NSDL National Science Digital Library

This comprehensive site contains facts, figures, references, teacher's aides, news, events, and much more on subjects pertaining to water. Some of the subjects touched on include aquatic ecosystems, groundwater, lakes, permafrost, properties of water, rivers, sediment, snow and ice, water and climate, and Wetlands. Water policy and legislation is also discussed and includes information on federal-provincial cooperation, international, legislation and regulation, provincial/territorial, and water policy in Canada. There is also a section on the management of water including bulk water removal and water export, Flood Damage Reduction Program, floods, water efficiency/conservation, water modeling, water pollution, water quality, water resource economics, and water use. The section on water and culture discusses Aboriginal issues, water and art, and water and Canadian identity. The site is available in English and French.

322

Water Resources Outreach Program - Water Education Posters  

NSDL National Science Digital Library

This site contains a series of six posters all relating to water education: wetlands, water use, waste water, navigation, ground water, and water quality. Each poster includes information about the topic as well as related classroom activities. The objective of the water-resources education program is to stimulate interest in and provide a basic knowledge of water resources for students in grades K-12. This United States Geological Survey (USGS) website is part of the Water Resources Education Initiative (WREI), a program developed by the USGS in 1991.

323

Water resources data, Alaska, water year 2005  

USGS Publications Warehouse

Water resources data for the 2005 water year for Alaska consist of records of stage, discharge, and water quality of streams; stages of lakes; and water levels and water quality of ground water. This volume contains records for water discharge at 114 gaging stations; stage or contents only at 3 gaging stations; water quality at 37 gaging stations; and water levels for 41 observation wells. Also included are data for 55 crest-stage partial-record stations. Additional water data were collected at various sites not involved in the systematic data-collection program and are published as miscellaneous measurements and analyses. Some data collected during 2005 will be published in subsequent reports. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in Alaska.

Jackson, M.L.; Castor, M.E.; Goetz, J.M.; Solin, G.L.; Wiles, J.M.

2006-01-01

324

Water resources data, Kansas, water year 2004  

USGS Publications Warehouse

Water-resources data for the 2004 water year for Kansas consist of records of stage, discharge, and water quality of streams; elevation and contents of lakes and reservoirs; and water levels of ground-water wells. This report contains records for water discharge at 155 complete-record gaging stations; elevation and contents at 17 lakes and reservoirs; water-quality records at 2 precipitation stations, water-level data at 14 observation wells; and records of specific conductance, pH, water temperature, dissolved oxygen, and turbidity at 16 gaging stations and 2 lakes with water-quality monitors. Also included are discharge data for 29 high-flow partial-record stations. These data represent that part of the National Water Information System collected by the U.S. Geological Survey in cooperation with local, State, and Federal agencies in Kansas.

Putnam, J.E.; Schneider, D.R.

2005-01-01

325

Radon in Drinking Water  

MedlinePLUS

... are here: EPA Home Air Indoor Air Radon Health Risks Drinking Water Radon in Drinking Water Public Health ... States and community water systems for reducing radon health risks in both drinking water and indoor air quality, ...

326

Sodium in Drinking Water  

MedlinePLUS

... To reduce my sodium intake, should I buy bottled water instead of using tap water? For more information. ... To reduce my sodium intake, should I buy bottled water instead of using tap water? It is not ...

327

Drinking Water Problems: Lead  

E-print Network

Lead in drinking water can damage the brain, kidneys, nervous system and red blood cells. This publication explains how lead can enter drinking water, how to have your water tested, and how to eliminate lead from drinking water....

Dozier, Monty; McFarland, Mark L.

2004-02-20

328

Autoionization of water  

NSDL National Science Digital Library

This site provides an animation showing the three normal vibrational modes of the water molecule as well as proton transfer in the following three situations: (1) hydronium ion/water, (2) hydroxide ion/water, and (3)two water molecules.

Merlic, Craig; Fam, Barry

329

Water: Consumer Information  

MedlinePLUS

... See EPA's (PDF) page to learn more. Your Drinking Water Quality Water On Tap: What You Need to ... Protecting Drinking Water Sources (PDF) (2 pp, 563K) Drinking Water Emergencies Learn what to do in the event ...

330

Arsenic in Drinking Water  

MedlinePLUS

... Water Act Arsenic in Drinking Water Arsenic in Drinking Water Arsenic iHome Basic Information Arsenic Rule Compliance Help ... table. It is odorless and tasteless. It enters drinking water supplies from natural deposits in the earth or ...

331

Important Water Quality Factors  

NSDL National Science Digital Library

This site provides basic information about factors commonly analyzed in water quality studies of drinking water, waste water and natural water. The factors are listed alphabetically with descriptions and explanations about what the results of measurements mean in environmental terms.

332

Treatment of Well Water  

MedlinePLUS

... message, please visit this page: About CDC.gov . Drinking Water Healthy Water Home Share Compartir On This Page ... a compromised immune system Improve the taste of drinking water Household water treatment systems are composed of two ...

333

Bottled Water and Fluoride  

MedlinePLUS

... Infant Formula and Fluorosis Scientific Reviews Fluoride in Drinking Water Health Effects and Environmental Impact Data & Statistics 2012 ... the quality of bottled water since it regulates drinking water? What FDA regulations apply to bottled water? Is ...

334

Alkali Soils, Irrigation Waters.  

E-print Network

, Ralmorhea, Reeves county. 2166-Water from Toyahvale, Reeves county. 2167'-Water froin Alexander's vell, 6 miles north of Pecos. 25'??-Water from Peco!: river at very low stage, Pecos. 2577---Water froni artesian well, 670 feei deep, for irrigating...

Fraps, G. S. (George Stronach)

1910-01-01

335

Land and water snails  

NSDL National Science Digital Library

Land snails live on the land and water snails make water their habitat. Land snails have shells to protect them and so do water snails. Land snails have two sets of antennae, while water snails only have one set.

Olivia Worland (Purdue University; Biological Sciences)

2008-06-03

336

Water Contamination Demonstration  

NSDL National Science Digital Library

Summary: Misplaced Matter and Water Pollution The drinking water pollution demonstration provides a very simple but dramatic way to get students to think about water contamination and drinking water standards, ...

337

Water Sensors  

NASA Technical Reports Server (NTRS)

Mike Morris, former Associate Director of STAC, formed pHish Doctor, Inc. to develop and sell a pH monitor for home aquariums. The monitor, or pHish Doctor, consists of a sensor strip and color chart that continually measures pH levels in an aquarium. This is important because when the level gets too high, ammonia excreted by fish is highly toxic; at low pH, bacteria that normally break down waste products stop functioning. Sales have run into the tens of thousands of dollars. A NASA Tech Brief Technical Support Package later led to a salt water version of the system and a DoE Small Business Innovation Research (SBIR) grant for development of a sensor for sea buoys. The company, now known as Ocean Optics, Inc., is currently studying the effects of carbon dioxide buildup as well as exploring other commercial applications for the fiber optic sensor.

1992-01-01

338

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE  

E-print Network

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE 212 AGRICULTURAL ENGINEERING BUILDING OF THE DIRECTOR . . · Once again during the spring 1973 semester the Nebraska Water Resources Research Institute will sponsor an Interdisciplinary Water Resources Seminar. These seminars have been held for the past five

Nebraska-Lincoln, University of

339

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE  

E-print Network

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE 212 AGRICULTURAL ENGINEERING BUILDING in water pollution except that land runoff is a more meaningful problem than originally thought. BUREAU STUDIES SALINE WATER A study to generate a dependable \\'tay of evaluating the economic effects of salinity

Nebraska-Lincoln, University of

340

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE  

E-print Network

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE 212 AGRICULTURAL ENGINEERING BUILDING Research application is an educational activity. Its aim is to pro- duce a change in the water resource environment by producing a change in people who manage water resources. #12;-2- 6. Provide Readable Reports

Nebraska-Lincoln, University of

341

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE  

E-print Network

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE 212 AGRICULTURAL ENGINEERING BUILDING during precipitation-free periods and constitutes the principal source of fresh water for many arid local- ities. About 70-80 percent of the water used in Nebraska is from groundwater sources, while the national

Nebraska-Lincoln, University of

342

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE  

E-print Network

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE 212 AGRICULTURAL ENGINEERING BUILDING~ November 1973 Opportunities for cost effective research related to energy-water issues are abundant. Many. It would be impossible to list all fruitful avenues for energy-water research, but some important issues

Nebraska-Lincoln, University of

343

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE  

E-print Network

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE 212 AGRICULTURAL ENGINEERING BUILDING LABLE FRm1 ~.~, VI I RI RI I · The Nebraska Water Resources Research Institute has recently issued a new. This publi- cation may be obtained by writing: Dr. Warren Viessman, Jr., Director, Nebraska Water Resources

Nebraska-Lincoln, University of

344

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE  

E-print Network

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE 212 AGRICULTURAL ENGINEERING BUILDING ALLOTMENT PROJECT DEADLINE The Nebraska Water Resources Research Institute is now prepared to receive basicIe. LB-334, enacted by the 1969 Legislature, authorized the Nebraska Soil a~d Water Conservation

Nebraska-Lincoln, University of

345

WATER RESOURCES ,'JEBRASKA WATER RESOURCES RESEARCH INSTITUTE  

E-print Network

WATER RESOURCES ,'JEBRASKA WATER RESOURCES RESEARCH INSTITUTE 212 AGRICULTURAL ENGINEERING BUILDING, 1973 Research in support of the state water resources planni n q proces s c a n 01" a highly productive actually be understood. It must also be understood that planning for the use and development of water

Nebraska-Lincoln, University of

346

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE  

E-print Network

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE 212 AGRICULTURAL ENGINEERING BUILDING,000,000 for the Sec. 101 matching grant program, and $2,000,000 for the Title II program. INTERDISCIPLINARY WATER RESOURCE SEMINAR An Interdisciplinary Water Resource Seminar will be offered during the 1970 Semeste

Nebraska-Lincoln, University of

347

1999 WATER RESOURCES SEMINARS "Spotlighting Water Research"  

E-print Network

Institute, Fountain Valley, CA March 31: "Unsaturated Hydraulic Properties for Movement of Water1999 WATER RESOURCES SEMINARS "Spotlighting Water Research" Wednesdays/3:00 to 3:50 p.m./116 L. W a Boost"--J. Michael Jess, Civil Engineer January 20: "Hydrologic Impact of Water Conservation Practices

Nebraska-Lincoln, University of

348

Water 3: Accounting For Our Water Needs  

NSDL National Science Digital Library

How do we account for water use? What is the difference between water consumed and water withdrawn? What is the water footprint tool? This video examines these questions. This video is part of the Sustainability Learning Suites, made possible in part by a grant from the National Science Foundation. See 'Learn more about this resource' for Learning Objectives and Activities.

Vanasupa, Linda

349

Virtual water trade and world water resources.  

PubMed

Global virtual water trade was quantitatively estimated and evaluated. The basic idea of how to estimate unit requirement of water resources to produce each commodity is introduced and values for major agricultural and stock products are presented. The concept of virtual water and the quantitative estimates can help in assessing a more realistic water scarcity index in each country, projecting future water demand for food supply, increasing public awareness on water, and identifying the processes wasting water in the production. Really required water in exporting countries is generally smaller than virtually required water in importing countries, reflecting the comparative advantage of water use efficiency, and it is estimated to be 680 km3/y for 2000. On the contrary the virtually required water for the same year is estimated to be 1,130 km3/y, and the difference of 450 km3/y is virtually saved by global trade. However, solely virtual water should not be used for any decision making since the idea of virtual water implies only the usage and influence of water and no concerns on social, cultural, and environmental implications. Virtual water trade also does not consider other limiting factors than water. PMID:15195440

Oki, T; Kanae, S

2004-01-01

350

Water chemistry and poultry processing water quality  

Technology Transfer Automated Retrieval System (TEKTRAN)

This study examined the influences of water chemistry on the quality of process water used in immersion chillers. During commercial poultry processing the bird carcasses come in direct contact with process water during washing and chilling operations. Contamination of the process water with bacteria...

351

Waters of the Earth  

NSDL National Science Digital Library

In this lesson, students make a visual display showing the distribution of water on earth. Using separate bottles, students illustrate the amount of water in oceans, fresh water locked up as ice, underground fresh water, surface fresh water, and water in air and soil.

352

Water Reactive Materials  

Microsoft Academic Search

Water reactive chemicals are generally aggressive materials that are used widely in the process industries. Common water reactive substances are sulphur trioxide, oleum, titanium tetrachloride, silicon tetrachloride, chlorosulphonic acid, chloroacetyl chloride and phosphorus trichloride. When released to the atmosphere, water reactive materials generally react readily with any free ground water, substrate water and atmospheric water. The exact nature, kinetics and

L. Fernie; P. Wright; T. Kapias

2007-01-01

353

Water Resources Policy & Economics  

E-print Network

Water Resources Policy & Economics FOR 4984 Selected Course Topics · Appropriative and riparian water institutions · Incentives for conservation · Water rights for in-stream environmental use · Surface water-groundwater management · Water quality regulations · Water markets · Economic and policy

Buehrer, R. Michael

354

Testing the Waters.  

ERIC Educational Resources Information Center

Provides information about home drinking water treatment systems to address concerns about the safety and quality of drinking water. Discusses water testing, filtration, product options and selection, water testing resources, water treatment device guidelines, water analysis terminology, and laboratory selection. (MCO)

Finks, Mason

1993-01-01

355

MODELING WATER QUALITY  

Technology Transfer Automated Retrieval System (TEKTRAN)

Water quality models are based on some representation of hydrology and may include movement of surface water, ground water, and mixing of water in lakes and water bodies. Water quality models simulate some combination of sediment, nutrients, heavy metals, xenobiotics, and aquatic biology. Althoug...

356

Mass Production and High Photocatalytic Activity of ZnS Nanoporous Nanoparticles  

Microsoft Academic Search

Environmental problems associated with organic pollutants and toxic water pollutants provide the impetus for sustained fundamental and applied research in the area of environ- mental remediation. Semiconductor photocatalysis offers the potential for complete elimination of toxic chemicals through its efficiency and potentially broad applicability.(1) Various new compounds and materials for photocatalysis have been synthesized in the past few decades. A

Jin-Song Hu; Ling-Ling Ren; Yu-Guo Guo; An-Min Cao; Li-Jun Wan; Chun-Li Bai; Angewandte Chemie

2005-01-01

357

The Fluid Interface Reactions Structures and Transport (FIRST) EFRC (A "Life at the Frontiers of Energy Research" contest entry from the 2011 Energy Frontier Research Centers (EFRCs) Summit and Forum)  

ScienceCinema

'The Fluid Interface Reactions Structures and Transport (FIRST) EFRC' was submitted by FIRST to the 'Life at the Frontiers of Energy Research' video contest at the 2011 Science for Our Nation's Energy Future: Energy Frontier Research Centers (EFRCs) Summit and Forum. Twenty-six EFRCs created short videos to highlight their mission and their work. FIRST, an EFRC directed by David J. Wesolowski at the Oak Ridge National Laboratory is a partnership of scientists from nine institutions: Oak Ridge National Laboratory (lead), Argonne National Laboratory, Drexel University, Georgia State University, Northwestern University, Pennsylvania State University, Suffolk University, Vanderbilt University, and University of Virginia. The Office of Basic Energy Sciences in the U.S. Department of Energy's Office of Science established the 46 Energy Frontier Research Centers (EFRCs) in 2009. These collaboratively-organized centers conduct fundamental research focused on 'grand challenges' and use-inspired 'basic research needs' recently identified in major strategic planning efforts by the scientific community. The overall purpose is to accelerate scientific progress toward meeting the nation's critical energy challenges. The mission of Fluid Interface Reactions, Structures and Transport Center is 'to develop quantitative and predictive models of the unique nanoscale environment at fluid-solid interfaces that will enable transformational advances in electrical energy storage and heterogeneous catalysis for solar fuels.' Research topics are: catalysis (biomass, CO{sub 2}, water), electrocatalysis, photocatalysis, photoelectrocatalysis, solar fuels, solar electrodes, electrical energy storage, batteries, capacitors, battery electrodes, electrolytes, extreme environment, CO{sub 2} (convert), greenhouse gas, microelectromechanical systems (MEMS), interfacial characterization, matter by design, novel materials synthesis, and charge transport.

Wesolowski, David J. (Director, FIRST - Fluid Interface Reactions, Structures, and Transport Center); FIRST Staff

2011-11-02

358

Magnificent Ground Water Connection  

NSDL National Science Digital Library

The Magnificent Ground Water Connection is a compilation of ground water-related activities for teaching and learning purposes. The teacher's activity guide is applicable to a wide range of subject matter and the ground water theme is integrated into stories, songs, math, social studies, art and writing. The topics include basic concepts of the water cycle, water distribution, treatment and stewardship. Other subjects include the water cycle and water conservation, New England's ground water resources, ground water contamination and protection. Sections are also available for wetlands, ground water, marine debris, waster, air quality, acid rain, and energy. Users can also access an on-line lending library for educational materials and videos.

359

The Water Cycle  

NSDL National Science Digital Library

Students will learn the process of the water cycle. Alabama Course of Study: Science. Second Grade: Standard 9: Describe evaporation, condensation, and precipitation in the water cycle. What is the water cycle? On the worksheet provided, list the 4 parts of the water cycle. Between the parts draw a small picture to represent what is happening during this cycle. The Water Cycle See how we use the water in the water cycle. Thirstins Water Cycle Name 3 ways water changes form. This is an animated diagram of the Water Cycle Here is a ...

Lopez, Mrs.

2009-07-09

360

Molecular Structure of Water  

NSDL National Science Digital Library

Water descends from the sky as rain and irrigates the land. Water can be used as a solvent for dissolving many forms of solids. It can also be used as both a coolant and a reactant. Everything from blood to tears are variations of the water compound. Water quality is an important issue in the environment. Safe water, water free of harmful toxins, is important for agriculture and community consumption. Criteria for safe water is based on levels deemed suitable for drinking, swimming, farming etc. The EPA uses specific water safety standards used by many states for water safety management. States may also adopt their own water safety standards for government approval.

2002-08-14

361

Smart Water: Energy-Water Optimization in Drinking Water Systems  

EPA Science Inventory

This project aims to develop and commercialize a Smart Water Platform ? Sensor-based Data-driven Energy-Water Optimization technology in drinking water systems. The key technological advances rely on cross-platform data acquisition and management system, model-based real-time sys...

362

Water, Water Everywhere: Phase Diagrams of Ordinary Water Substance  

ERIC Educational Resources Information Center

The full phase diagram of water in the form of a graphical representation of the three-dimensional (3D) PVT diagram using authentic data is presented. An interesting controversy regarding the phase behavior of water was the much-touted proposal of a solid phase of water, polywater, supposedly stable under atmospheric conditions.

Glasser, L.

2004-01-01

363

Minimal Proton Channel Enables H2 Oxidation and Production with a Water-Soluble Nickel-Based Catalyst  

SciTech Connect

Hydrogenase enzymes efficiently interconvert H2 and H+ using first row transition metals with low overpotentials and high rates in aqueous solution. The development of efficient electrocatalysts mimicking the properties of hydrogenase enzymes for fuel and electrolysis cells based upon abundant and inexpensive metals could enable the widespread use of renewable fuels such as solar and wind. However, molecular electrocatalysts are typically unable to operate bidirectionally and are notably unable to meet the overall efficiency of the enzyme in either direction. Here we show that introducing an amino acid residue in the outer coordination sphere of a Ni-based complex Ni(PCy2NGlycine2)2 creates an electrocatalyst that is active and efficient for hydrogen oxidation (5-8 s-1, overpotential=44-250 mV) over a range of moderate pH values (3.5-9.0). Hydrogen production can be achieved from the same complex under identical solution conditions (>1200 s-1). Proton transfer from the amino acid carboxylates in the outer coordination sphere to the pendant amines in the second coordination sphere is observed by NMR and IR, signifying a plausible role of the carboxylate groups in creating a proton channel for proton removal and delivery during the catalytic cycle. These results with this first generation water soluble Ni(PR2NR’2)2 complex indicate that fast, bidirectional (hydrogen production/oxidation) catalysis for molecular catalysts is achievable. This work was funded by the Office of Science Early Career Research Program through the USDOE, BES (AD, SL, WJS), and the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the US DOE, Office of Science, Office of BES (JH, JASR). Part of the research was conducted at the W.R. Wiley Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by U.S. DOE’s Office of Biological and Environmental Research (BER) program located at Pacific Northwest National Laboratory (PNNL). PNNL is operated by Battelle for the U.S. Department of Energy.

Dutta, Arnab; Lense, Sheri; Hou, Jianbo; Engelhard, Mark H.; Roberts, John A.; Shaw, Wendy J.

2013-11-08

364

A Proton Channel Allows a Hydrogen Oxidation Catalyst to Operate at a Moderate Overpotential with Water Acting as a Base  

SciTech Connect

Proton channels facilitate the movement of protons over large distances and are critical in many reactions, from controlling proton delivery in metalloenzymes[1] to moving protons through PEM fuel cells.[2] Hydrogenases are enzymes that use proton channels to deliver protons to or from the enzyme active site to achieve high rates of hydrogen production and oxidation at low overpotentials.[3] The [Ni(PR2NR’2)2]2+ series of complexes, which are functional mimics of the [FeFe]-hydrogenase active site, utilize pendant amines to move the proton to or from the Ni, resulting in some of the fastest synthetic catalysts for hydrogen production and oxidation reported.[4] While intramolecular proton movement has been shown to be facile,[5] deprotonation of hydrogen oxidation catalysts can be a slow step for catalysis.[6] Additionally, a stable H2 adduct (endo-endo) is formed which, if bypassed, could contribute to an overall enhanced rate (Figure 1). A proton channel may aid in addressing these outstanding issues, and the well-studied nature of these catalysts allows them to serve as a platform to investigate the role of a proton channel in solving these problems. To this end we added a second proton relay to this complex, which we demonstrate serves two purposes: we show that the second proton relay facilitates rapid proton transfer, altering the kinetic products formed following H2 addition, and avoiding the low energy endo-endo intermediate. It also aids in lowering the overpotential at which the catalyst operates using water as a base, demonstrating the multi-functional role of a proton channel in molecular catalysts, and possibly in enzymes. This work was supported by the US Department of Energy, Early Career Research Program, Basic Energy Sciences, Chemical Sciences, Geosciences & Biosciences Division and by the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

Lense, Sheri J.; Dutta, Arnab; Roberts, John A.; Shaw, Wendy J.

2014-01-25

365

Global water use inequality  

NASA Astrophysics Data System (ADS)

The distribution of renewable freshwater resources between countries is highly unequal and 80% of humanity lives in regions where water security is threatened. Freshwater is a finite resource and a more equal distribution of water may be necessary in order to ensure that all populations are adequately provisioned. We evaluated inequality in blue, green, and gray water use between nations and assessed the ability of virtual water transfers to reduce inequality in global water use. Overall, the actual use of renewable water resources is relatively equal even though the physical distribution of renewable water resources is highly unequal. Most inequality in water use is due to agricultural production and can be attributed to climate and arable land availability. Virtual water transfer is unlikely to increase water-use equality primarily because agricultural water use dominates national water needs and this cannot be completely compensated by virtual water transfers.

Seekell, D. A.; D'Odorico, P.; Pace, M. L.

2011-12-01

366

Cloud Liquid Water Measurements  

E-print Network

#12;Wet Power Term Energy is transferred to heat droplets to to the boiling point and vaporize of Vaporization · cw - Specific Heat of Water · Tv - Boiling Temperature of Water · Ta ­ Ambient Temperature #12 of Vaporization · cw - Specific Heat of Water · Tv ­ Water Boiling Temperature Solve for Liquid Water Content · P

Delene, David J.

367

Arkansas Water Resources Center  

E-print Network

to the Arkansas Soil and Water Conservation Commission By Marc A. Nelson Arkansas Water Resources Center Ron Redman Arkansas Soil and Water Conservation Commission L. Wade Cash Arkansas Water Resources Center G ROAD 76 BRIDGE ON BALLARD CREEK Submitted to: Arkansas Soil and Water Conservation Commission By: Marc

Soerens, Thomas

368

Save Our Water Resources.  

ERIC Educational Resources Information Center

The purpose of this booklet, developed as part of Project SOAR (Save Our American Resources), is to give Scout leaders some facts about the world's resources, the sources of water pollution, and how people can help in obtaining solutions. Among the topics discussed are the world's water resources, the water cycle, water quality, sources of water

Bromley, Albert W.

369

Water Regulation I. Osmoregulation  

E-print Network

1 Water Regulation I. Osmoregulation II. Water Gain III. Water loss IV. Extreme Environments Animal matched over time, or else!!! I. Osmoregulation ­ water balance l Different problems with osmoregulation depending on the habitat the organism lives in A. Freshwater: B. Salt water: C. Terrestrial: Excessive

Dever, Jennifer A.

370

Water Regulation I. Osmoregulation  

E-print Network

1 Water Regulation I. Osmoregulation II. Water Gain III. Water loss IV. Extreme Environments I. Osmoregulation ­ water balance Animal = open system that exchanges materials & energy w/environment. Rates depending on the habitat the organism lives in A. Freshwater: the animal is hyperosmotic B. Salt water

Dever, Jennifer A.

371

Water Regulation I. Osmoregulation  

E-print Network

1 Water Regulation I. Osmoregulation II. Water Gain III. Water loss IV. Extreme Environments I. Osmoregulation ­ water balance Animal = open system that exchanges materials & energy w/environment. Different is hyperosmotic B. Salt water: the animal is hypoosmotic C. Terrestrial: evaporation main problem Excessive

Dever, Jennifer A.

372

Water Regulation I. Osmoregulation  

E-print Network

1 Water Regulation I. Osmoregulation II. Water Gain III. Water loss IV. Extreme Environments I. Osmoregulation ­ water balance l Different problems with osmoregulation depending on the habitat the organism lives in #12;2 Nitrogenous Wastes 1) Ammonia 2) Urea 3) Uric Acid II. Water Gain 1. Drinking (reptiles

Dever, Jennifer A.

373

Rendering Natural Waters  

Microsoft Academic Search

Creating and rendering realistic water is one of the most daunting tasks in computer graphics. Realistic rendering of water requires that the sunlight and skylight illumination are correct, the water surface is modeled accurately and that the light transport within water body is properly handled. This paper describes a method for wave generation on a water surface using a physically-based

Simon Premoze; Michael Ashikhmin

2001-01-01

374

Plant Water Relations  

NSDL National Science Digital Library

Plant water relations are presented in this learning activity to help participants understand the components of water potential, explain how water moves through plants, provide examples of plant adaptations to water stress, and have a general understanding of how water potential can be measured.

Bidlack, Jim

375

Water Basins Civil Engineering  

E-print Network

Water Basins Civil Engineering Objective · Connect the study of water, water cycle, and ecosystems with engineering · Discuss how human impacts can effect our water basins, and how engineers lessen these impacts: · The basic concepts of water basins are why they are important · To use a topographic map · To delineate

Provancher, William

376

Grains, Water Introduction  

E-print Network

Grains, Water & Wet Sand Onno Bokhove Introduction Dry Granular Chute Flows: Cantilever Water Waves: Bores Near the Shore Surf Induced Sand Dynamics Discussion Dry Granular Flows, Water Waves & Surf, Water & Wet Sand Onno Bokhove Introduction Dry Granular Chute Flows: Cantilever Water Waves: Bores Near

Wirosoetisno, Djoko

377

Water Resources of Idaho  

NSDL National Science Digital Library

This United States Geological Survey (USGS) website highlights water resources in the state of Idaho. Details about hydrology programs in the state include ground water data, water quality information, water use in the state of Idaho, surface water, Idaho programs, reports, flood and drought information, and state projects on ice core research and various rivers. There are links to more sites for additional information.

378

Human Water Cycle  

NSDL National Science Digital Library

Students learn about the human water cycle, or how humans impact the water cycle by settling down in civilizations. Specifically, they learn how people obtain, use and dispose of water. Students also learn about shortages of treated, clean and safe water and learn about ways that engineers address this issue through water conservation and graywater recycling.

Integrated Teaching and Learning Program,

379

Acid in water  

NSDL National Science Digital Library

Plants and animals that live in water create some amount of acid in the water. The carbon dioxide that plants and animals release into the water makes the water acidic and unsafe for living organisms. This is why the water of captive aquatic animals and plants must be changed often.

Laszlo Ilyes (None;)

2007-05-16

380

Arkansas Water Resources Center  

E-print Network

Arkansas Water Resources Center LASER-PHOTOACOUSTIC DETECTION OF WATER POLLUTANTS PHASE I Principal. '. 18 #12;cor~PLETIONREPORT LASER-PHOTOACOUSTICDETECTIONOF WATER POLLUTANTS: PHASEI October ls 1977 their waters. Recognizing that water pollution can pose serious health hazards and unknown long term effects

Soerens, Thomas

381

Water Governance and Legislation  

NSDL National Science Digital Library

Visitors to this site can review Canadian water policy and legislation for both provinces and federal government. Topics include the nature of water, water policy and legislation, water management, water and culture, and links to information and services (a glossary, news articles, and a teachers' corner). A French translation is available.

2003-07-31

382

Water Pollution. Project COMPSEP.  

ERIC Educational Resources Information Center

This is an introductory program on water pollution. Examined are the cause and effect relationships of water pollution, sources of water pollution, and possible alternatives to effect solutions from our water pollution problems. Included is background information on water pollution, a glossary of pollution terminology, a script for a slide script…

Lantz, H. B., Jr.

383

Introduction to Water Chemistry  

NSDL National Science Digital Library

Students are presented with examples of the types of problems that environmental engineers solve, specifically focusing on water quality issues. Topics include the importance of clean water, the scarcity of fresh water, tap water contamination sources, and ways environmental engineers treat contaminated water.

GK-12 Program,

384

Water resources data, Nevada, water year 2003  

USGS Publications Warehouse

Water-resources data for the 2003 water year for Nevada consists of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; precipitation; and water levels in wells. This report contains discharge records for 182 streamflow-gaging stations on streams, canals and drains; Discharge data for 52 partial record stations and miscellaneous sites, and 23 springs; stage and contents records for 21 ponds, lakes and reservoirs; Water levels for 178 primary observation wells, and 715 secondary observation wells; Water-quality data for 70 streams, canal, spring and drain sites and 276 wells; precipitation totals for 40 stations; and water withdrawals for 11 wells.

Stockton, Emil L.; Jones, Clifford Z.; Rowland, Ryan C.; Medina, Rose L.

2003-01-01

385

Industrial Water Demand With Water Reuse  

Microsoft Academic Search

This work establishes an industrial water demand (IWD) model for a short term estimate, which considers water reuse technologies and discharge regulations, for the integrated circuit (IC) industry in northern Taiwan. Based on the optimization of an industrial water cost system, a computerized system dynamics model (SD model) is developed to generate individual firm IWD using data from year 2000.

Chao-Hsien Liaw; Liang-Ching Chen; Li-Mei Chan

2006-01-01

386

WATER RECLAMATION AND AUTOMATED WATER QUALITY MONITORING  

EPA Science Inventory

The Santa Clara Valley Water District owns and operates a water reclamation facility located in the Palo Alto Baylands area in Northern California. The purpose of the facility is to provide reclaimed water suitable for injection into the groundwater, thereby providing a salt wate...

387

Water: Human Health  

MedlinePLUS

... Quality Standards Water Quality Criteria Human Health Criteria Human Health Criteria Human health ambient water quality criteria ... Updated National Recommended Water Quality Criteria - Human Health Human Health Research Program Human Health Research provides the ...

388

water transport land runoff  

E-print Network

Monitoring station Land to water transport Urban runoff Cultivated land runoff Wastewater discharges Pasture land runoff Instream transport and removal Land to water transport Monitoring station Benefits of Integrated Monitoring and Modeling Successful management of our Nation's water resources

Torgersen, Christian

389

Aging Water Infrastructure  

EPA Science Inventory

The Aging Water Infrastructure (AWI) research program is part of EPA?s larger effort called the Sustainable Water Infrastructure (SI) initiative. The SI initiative brings together drinking water and wastewater utility managers; trade associations; local watershed protection organ...

390

Lawn Water Management  

E-print Network

Water is a limited resource in Texas. This booklet explains how homeowners can establish a water management program for a home lawn that both maintains a healthy sod and also conserves water. The publication discusses soil types, grass varieties...

McAfee, James

2006-06-26

391

Reduction of Water Consumption  

E-print Network

Cooling systems using water evaporation to dissipate waste heat, will require one pound of water per 1,000 Btu. To reduce water consumption, a combination of "DRY" and "WET" cooling elements is the only practical answer. This paper reviews...

Adler, J.

392

Water Words Dictionary: A Compilation of Technical Water, Water Quality, Environmental, and Water-Related Terms  

NSDL National Science Digital Library

The Water Words Dictionary: A Compilation of Technical Water, Water Quality, Environmental, and Water-Related Terms is a helpful collection of resources for water researchers and professionals provided by the Nevada Division of Water Resources and the Department of Conservation and Natural Resources. This extensive and freely accessed dictionary contains hundreds of words, which are organized alphabetically, making it perfect for searching and printing. Also provided are dozens of appendixes, abbreviations and acronyms, conversion tables and flow equivalents, and more.

393

Water Resources of Tennessee  

NSDL National Science Digital Library

This site, from the U.S. Geological Survey, provides real-time, surface-water, ground-water and water-quality data; maps and graphs of current water resource conditions in the U.S. such as a daily streamflow conditions map; publications and product information; information on National Water-Quality Assessment (NAWQA) programs of the Tennessee River Basin and Mobile River Basin; and information on water use in Tennessee.

394

Water Cycle Webquest  

NSDL National Science Digital Library

Students are introduced to the Global Precipitation Measurement (GPM) satellite mission and its role in studying the water cycle. This webquest provides links to eight websites, allowing middle school students to explore the water cycle and its impacts on Earth's weather and climate. Through online videos and articles, students follow a water molecule through the cycle, discover the connection between the water cycle and global water/heat distribution, examine the role of solar energy, and assess the importance of fresh water.

395

Industrial Water Use  

NSDL National Science Digital Library

As part of its Water Science for Schools site, the US Geological Survey defines industrial water use and includes several tables and maps showing where and how industry uses water. Students and teachers can look at their state and see 1990 data for how much ground water and how much surface water is used in industry as well as how much of that water is fresh or saline.

2002-10-10

396

Water Resources Research Center  

NSDL National Science Digital Library

Visitors can access information on a variety of water issues in Arizona, including the Colorado River, riparian areas, water conservation, water rights, and recreation. The Arizona Water Resources Research Center (WRRC) provides FAQâs, a stream gauge map and a directory of water-related agencies and organizations. Real-time temperature, precipitation, wind speed and direction, and humidity readouts are available via the new WRRC weather station. Other materials include news articles, research reports, presentations, and links to other water-related sites.

397

Industrial Water Demand With Water Reuse  

NASA Astrophysics Data System (ADS)

This work establishes an industrial water demand (IWD) model for a short term estimate, which considers water reuse technologies and discharge regulations, for the integrated circuit (IC) industry in northern Taiwan. Based on the optimization of an industrial water cost system, a computerized system dynamics model (SD model) is developed to generate individual firm IWD using data from year 2000. A market IWD is further constructed for 25 IC firms in the study area and is approximated by an inverse logistic curve. Analytical results demonstrate that price elasticity varies with water price in cases involving water reuse.

Liaw, Chao-Hsien; Chen, Liang-Ching; Chan, Li-Mei

2006-06-01

398

Trees, Soil and Water  

NSDL National Science Digital Library

Trees, soil and water: Journey to Forever - health care for mountains, trees for deserts, trees for people, forest, forestry, deforestation, erosion, soil conservation, water conservation, desertification.

Keith Addison

2010-01-01

399

Walk On Water Bugs  

NSDL National Science Digital Library

In this activity (on pages 29-35), learners examine water pollution and filtration. First, learners build models of water bugs from paper clips, and test the effect of dirt and detergent on their "bugs" floating on the water. Next, learners build a water filter using filter paper, a paper towel, and gravel or sand. The "What We Know" section introduces concepts of how much drinking water is found on Earth, water pollution, the impact of pollution on water quality and surface tensionâand how that affects specially adapted species such as water striders.

Museum, University O.; Nebraska Cooperative Extension 4-H Youth Development

2001-01-01

400

Revealing water’s secrets: deuterium depleted water  

PubMed Central

Background The anomalous properties of water have been of great interest for generations of scientists. However the impact of small amount of deuterium content which is always present in water has never been explored before. For the first time the fundamental properties of deuterium depleted (light) water at 4°C and 20°C are here presented. Results The obtained results show the important role of the deuterium in the properties of bulk water. At 4°C the lowest value of the kinematic viscosity (1.46 mm2/s) has been found for 96.5 ppm D/H ratio. The significant deviation in surface tension values has been observed in deuterium depleted water samples at the both temperature regimes. The experimental data provides direct evidence that density, surface tension and viscosity anomalies of water are caused by the presence of variable concentration of deuterium which leads to the formation of water clusters of different size and quantity. Conclusions The investigated properties of light water reveal the origin of the water anomalies. The new theoretical model of cluster formation with account of isotope effect is proposed. PMID:23773696

2013-01-01

401

Photocatalysis for the destruction of aqueous TNT, RDX, and HMX  

SciTech Connect

The photo-destruction of the high explosives HMX, RDX and TNT was investigated using two systems (ozone versus titanium dioxide), two reactors (pot vs annular reactor), and two types of lamps (1000 Watt Hg-Xe vs 25 Watt LP Hg). A mass balance was performed on reactions executed under pseudo-solar conditions, and relative reaction rates and products were compared for ozone and titanium dioxide based processes. The ratios of relative product formation is also discussed. Results show that there was little difference in the reactions performed in the annular reactor when either ozone or titanium oxide were used. The chemistry of RDX and HMX are very similar, as expected. Future work involving the mechanism is also discussed.

Showalter, S.K.; Prairie, M.R.; Stange, B.M.; Rodacy, P.J.; Leslie, P.K.

1994-12-31

402

Development of a microfluidic device for blood oxygenation by photocatalysis  

E-print Network

Recent statistics provided by the American Lung Association assert that over 400,000 Americans die every year from lung disorders and more than 35 million are now living with symptoms of lung disease. Mortality rates of ...

Ullah, Tania

2009-01-01

403

Photocatalysis for Renewable Energy Production Using PhotoFuelCells.  

PubMed

The present work is a short review of our recent studies on PhotoFuelCells, that is, photoelectrochemical cells which consume a fuel to produce electricity or hydrogen, and presents some unpublished data concerning both electricity and hydrogen production. PhotoFuelCells have been constructed using nanoparticulate titania photoanodes and various cathode electrodes bearing a few different types of electrocatalyst. In the case where the cell functioned with an aerated cathode, the cathode electrode was made of carbon cloth carrying a carbon paste made of carbon black and dispersed Pt nanoparticles. When the cell was operated in the absence of oxygen, the electrocatalyst was deposited on an FTO slide using a special commercial carbon paste, which was again enriched with Pt nanoparticles. Mixing of Pt with carbon paste decreased the quantity of Pt necessary to act as electrocatalyst. PhotoFuelCells can produce electricity without bias and with relatively high open-circuit voltage when they function in the presence of fuel and with an aerated cathode. In that case, titania can be sensitized in the visible region by CdS quantum dots. In the present work, CdS was deposited by the SILAR method. Other metal chalcogenides are not functional as sensitizers because the combined photoanode in their presence does not have enough oxidative power to oxidize the fuel. Concerning hydrogen production, it was found that it is difficult to produce hydrogen in an alkaline environment even under bias, however, this is still possible if losses are minimized. One way to limit losses is to short-circuit anode and cathode electrode and put them close together. This is achieved in the "photoelectrocatalytic leaf", which was presently demonstrated capable of producing hydrogen even in a strongly alkaline environment. PMID:25438083

Michal, Robert; Sfaelou, Stavroula; Lianos, Panagiotis

2014-01-01

404

Green Photocatalysis for Degradation of Organic Contaminants: A Review  

EPA Science Inventory

Many organic pesticides that were banned a few decades ago, as well as those that are currently in use in many parts of the world, pose some serious threat to human life and the ecosystem because of their persistent and bioaccumulative nature. In the recent years advanced oxidati...

405

CLEANER SYNTHESIS OF ORGANIC COMPOUNDS USING SEMICONDUCTER PHOTOCATALYSIS  

EPA Science Inventory

The chemical industry is a significant component of the domestic economy, generating well over $250 billion in sales and a trade surplus exceeding $15 billion in each of the last 5 years. The industry is also a major source of industrial waste and is the dominant source of hazard...

406

Carbon-modified TiO2 for photocatalysis  

PubMed Central

Here we present a method to produce TiO2 nanocrystals coated by thin layer of graphitic carbon. The coating process was prepared via chemical vapor deposition (CVD) with acetylene used as a carbon feedstock with TiO2 used as a substrate. Different temperatures (400°C and 500°C) and times (10, 20, and 60 s) of reaction were explored. The prepared nanocomposites were investigated by means of transmission electron microscopy, Raman spectroscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy/diffuse reflectance spectroscopy and ultraviolet-vis (UV-vis)/diffuse reflectance spectroscopy. Furthermore, photocatalytic activity of the materials was investigated under visible and UV-vis light irradiation in the process of phenol decomposition. It was found that TiO2 modification with carbon resulted in a significant increase of photoactivity under visible irradiation and decrease under UV-vis light irradiation. Interestingly, a shorter CVD time and higher process temperature resulted in the preparation of the samples exhibiting higher activity in the photocatalytic process under visible light irradiation. PMID:22537341

2012-01-01

407

Photocatalysis and Photoelectrochemical Properties of Tungsten Trioxide Nanostructured Films  

PubMed Central

Tungsten trioxide (WO3) possesses a small band gap energy of 2.4–2.8?eV and is responsive to both ultraviolet and visible light irradiation including strong absorption of the solar spectrum and stable physicochemical properties. Thus, controlled growth of one-dimensional (1D) WO3 nanotubular structures with desired length, diameter, and wall thickness has gained significant interest. In the present study, 1D WO3 nanotubes were successfully synthesized via electrochemical anodization of tungsten (W) foil in an electrolyte composed of 1?M of sodium sulphate (Na2SO4) and ammonium fluoride (NH4F). The influence of NH4F content on the formation mechanism of anodic WO3 nanotubular structure was investigated in detail. An optimization of fluoride ions played a critical role in controlling the chemical dissolution reaction in the interface of W/WO3. Based on the results obtained, a minimum of 0.7?wt% of NH4F content was required for completing transformation from W foil to WO3 nanotubular structure with an average diameter of 85?nm and length of 250?nm within 15?min of anodization time. In this case, high aspect ratio of WO3 nanotubular structure is preferred because larger active surface area will be provided for better photocatalytic and photoelectrochemical (PEC) reactions. PMID:24782669

Lai, Chin Wei

2014-01-01

408

Visible photocatalysis and photostability of Ag3PO4 photocatalyst  

NASA Astrophysics Data System (ADS)

Ag3PO4 photocatalyst was prepared by precipitation method and characterized by SEM, XRD and diffusive reflectance UV-vis (DRUV-vis) absorption spectra. The gas-phase photodegradation of volatile organic compounds (VOCs) such as benzene and acetone, and the liquid-phase photodegradation of the cationic and anionic dyes on Ag3PO4 were systematically investigated. Both benzene and acetone could not be photodegraded on the Ag3PO4 photocatalyst under the visible irradiation. The Ag3PO4 photocatalyst is efficient for the photodegradation of the aqueous dye solutions, but could not completely photomineralize the dyes to CO2 and H2O. The reason is discussed by comparing the oxidation potential of organic pollutants and the potential of photogenerated holes in Ag3PO4, and measuring the absorption of organic pollutants on Ag3PO4. The photostability of the Ag3PO4 photocatalyst for the photo-degradation of the dyes was tested. The Ag3PO4 photocatalyst itself is photostable in the absence of the scavenger of the photogenerated holes, but is photocatalytically instable in the liquid-phase photodegradation of dyes due to the photoreduction of Ag+ in Ag3PO4 to Ag.

Luo, Lin; Li, Yuanzhi; Hou, Jingtao; Yang, Yi

2014-11-01

409

Photocatalytic Water Splitting with Suspended Calcium Niobium Oxides: Why Nanoscale is Better than Bulk -A Kinetic Analysis  

E-print Network

for photocatalysis with semiconductor particles. The model calculates the electronic rate of the catalysts of nanoscaling, sacrificial charge donors, cocatalysts, and cocatalyst deposition conditions on the activity increases O2 production to 400 mol of O2/h/g. Rates for H2 and O2 evolution further depend on the presence

Osterloh, Frank

410

2010 Water & Aqueous Solutions  

SciTech Connect

Water covers more than two thirds of the surface of the Earth and about the same fraction of water forms the total mass of a human body. Since the early days of our civilization water has also been in the focus of technological developments, starting from converting it to wine to more modern achievements. The meeting will focus on recent advances in experimental, theoretical, and computational understanding of the behavior of the most important and fascinating liquid in a variety of situations and applications. The emphasis will be less on water properties per se than on water as a medium in which fundamental dynamic and reactive processes take place. In the following sessions, speakers will discuss the latest breakthroughs in unraveling these processes at the molecular level: Water in Solutions; Water in Motion I and II; Water in Biology I and II; Water in the Environment I and II; Water in Confined Geometries and Water in Discussion (keynote lecture and poster winners presentations).

Dor Ben-Amotz

2010-08-13

411

Water-heating dehumidifier  

DOEpatents

A water-heating dehumidifier includes a refrigerant loop including a compressor, at least one condenser, an expansion device and an evaporator including an evaporator fan. The condenser includes a water inlet and a water outlet for flowing water therethrough or proximate thereto, or is affixed to the tank or immersed into the tank to effect water heating without flowing water. The immersed condenser design includes a self-insulated capillary tube expansion device for simplicity and high efficiency. In a water heating mode air is drawn by the evaporator fan across the evaporator to produce cooled and dehumidified air and heat taken from the air is absorbed by the refrigerant at the evaporator and is pumped to the condenser, where water is heated. When the tank of water heater is full of hot water or a humidistat set point is reached, the water-heating dehumidifier can switch to run as a dehumidifier.

Tomlinson, John J. (Knoxville, TN)

2006-04-18

412

Safety of Bottled Water Beverages Including Flavored Water and Nutrient-Added Water Beverages  

MedlinePLUS

... Women Kids & Teens FDA Regulates the Safety of Bottled Water Beverages Including Flavored Water and Nutrient-Added Water ... carbonated soft drinks out-sell bottled water. Defining "Bottled Water" Under FDA labeling rules, bottled water includes products ...

413

Sustainability and Water  

NASA Astrophysics Data System (ADS)

World's population numbered 6.1 billion in 2000 and is currently increasing at a rate of about 77 million per year. By 2025, the estimated total world population will be of the order of 7.9 billion. Water plays a central role in any systematic appraisal of life sustaining requirements. Water also strongly influences economic activity (both production and consumption) and social roles. Fresh water is distributed unevenly, with nearly 500 million people suffering water stress or serious water scarcity. Two-thirds of the world's population may be subjected to moderate to high water stress in 2025. It is estimated that by 2025, the total water use will increase by to 40%. The resources of water supply and recreation may also come under stress due to changes in climate such as water balance for Lake Balaton (Hungary). Conventional urban water systems such as water supply, wastewater, and storm water management are also currently going through stress and require major rethinking. To maintain urban water systems efficiently in the future, a flexibility approach will allow incorporation of new technologies and adaptation to external changes (for example society or climate change). Because water is an essential resource for sustaining health, both the quantity and quality of available water supplies must be improved. The impact of water quality on human health is severe, with millions of deaths each year from water-borne diseases, while water pollution and aquatic ecosystem destruction continue to rise. Additionally, emerging contaminants such as endocrine disruptor chemicals (EDCs), pharmaceuticals, and toxins in the water body are also of a great concern. An innovative ferrate(VI) technology is highly effective in removing these contaminants in water. This technology is green, which addresses problems associated with chlorination and ozonation for treating pollutants present in water and wastewater. Examples are presented to demonstrate the applications of ferrate(VI) technology to meet the demand of water in this century.

Sharma, Virender A.

2009-07-01

414

Water, Water, Everywhere: Phase Diagrams of Ordinary Water Substance  

Microsoft Academic Search

A three-dimensional phase diagram for ordinary water substance, with its solid, liquid, and vapor phases, based on fitted authentic experimental data is presented. Such an authentic diagram appears not to have been presented for water before, and may improve the understanding of its phase relationships. The nature of the IAPWS-95 equations, fitted to data, is discussed.

L. Glasser

2004-01-01

415

Potable water taste enhancement  

NASA Technical Reports Server (NTRS)

An analysis was conducted to determine the causes of and remedies for the unpalatability of potable water in manned spacecraft. Criteria and specifications for palatable water were established and a quantitative laboratory analysis technique was developed for determinig the amounts of volatile organics in good tasting water. Prototype spacecraft water reclamation systems are evaluated in terms of the essential palatability factors.

1974-01-01

416

Exploratorium: Exploring Water.  

ERIC Educational Resources Information Center

This issue of Exploratorium focuses on water and its varied uses in our environment. Articles include: (1) "Adventures with Water" (Eric Muller); (2) "Water: The Liquid of Life" (Karen E. Kalumuck); (3) "Water-Drop Projector" (Gorazd Planinsic); (4) "Waterways and Means" (Pearl Tesler); (5) "Explore Natural Phenomena in the Museum--and Just…

Brand, Judith, Ed.

2001-01-01

417

WATER QUALITY CRITERIA DOCUMENTS  

EPA Science Inventory

Background Water quality standards and criteria are the foundation for a wide range of programs under the Clean Water Act. Specifically, under section 304(a)(1) of the Clean Water Act it requires EPA to develop criteria for water quality that accurately re...

418

Arkansas Water Resources Center  

E-print Network

Submitted to the Arkansas Soil and Water Conservation Commission By M.A. Nelson L.W. Cash G.K. Trost to the Arkansas Soil and Water Conservation Commission M. A. Nelson, L. W. Cash, and G. K. Trost Arkansas Water Soil and Water Conservation Commission (ASWCC) and the U. S. Environmental Protection Agency (EPA

Soerens, Thomas

419

Arkansas Water Resources Center  

E-print Network

Submitted to the Washington County Conservation District and Arkansas Soil and Water Conservation Commission & WATER CONSERVATION COMMISSION INTRODUCTION In Northwest Arkansas, nutrients transported by surface water storage structures. In 1991, the Arkansas Soil and Water Conservation Commission (ASWCC) and the U. S

Soerens, Thomas

420

Water Waves Roger Grimshaw  

E-print Network

Water Waves Roger Grimshaw May 7, 2003 Abstract A short review of the theory of weakly nonlinear water waves, prepared for the forthcoming Encyclopedia of Nonlinear Science 1 Introduction Water waves nonlinear waves. Throughout the theory is based on the traditional assumptions that water is inviscid

421

Water Resources Milind Sohoni  

E-print Network

TD 603 Water Resources Milind Sohoni www.cse.iitb.ac.in/sohoni/ Lecture 2: Water cycle, stocks and flows () July 28, 2013 1 / 30 #12;The basic movement of water source: USGS. () July 28, 2013 2 / 30 #12, humidity and air flow. Formation of liquid-water in the Atmosphere-Cloud-Formation Coming Down Rain

Sohoni, Milind

422

Water Resources Milind Sohoni  

E-print Network

TD 603 Water Resources Milind Sohoni www.cse.iitb.ac.in/sohoni/ Lecture 8: Wells () August 28, 2012 project, utilizing enhanced ground-water. Water lifted from storage, to accumulate overnight from aquifer. Water from shallow aquifer, of about 7-8m thickness. accounts for about 30% of irrigation Unique

Sohoni, Milind

423

Water Resources Milind Sohoni  

E-print Network

TD 603 Water Resources Milind Sohoni www.cse.iitb.ac.in/sohoni/ Lecture 7: Regional Groundwater than the unit situations that we saw. Surface water/Groundwater interactions. lakes and streams springs (seepage) Ambient water-table movements Seasonal changes Inteference with other water end-users. Inherent

Sohoni, Milind

424

Muddy Waters . . . page 4  

E-print Network

Research Institute · Morse Hall, Durham, NH Water, Water Everywhere asdfghjk -- continued on page 2 HereMuddy Waters . . . page 4 Braving the Storm . . . page 5 Winter 2009 Vol. 8 Issue 1 A River Runs's water sys- tem would be fast disappearing from the face of the earth as the program drew to a close

Pringle, James "Jamie"

425

Global Water Distribution  

NSDL National Science Digital Library

How much water on Earth is fresh water? How much of that fresh water is found in icecaps? Lakes? Rivers? This interactive resource uses bar graphs to illustrate the relative distribution of fresh and salt water on Earth. Adapted from Oxford University Press.

WGBH Educational Foundation

2005-12-17

426

Reflections on Water (and \\  

Microsoft Academic Search

In theories of word meaning and concepts, "water" has been taken as a key case ofa natural kind term, and water of a natural kind. I address several questions including:What should a theory of the meaning of the word "water" look like, given observationsabout use of the word? Is there a category of liquids that is water, independent of thenames

Barbara C. Malt

427

New Folklore about Water.  

ERIC Educational Resources Information Center

Describes experiments designed to investigate the cooling rate of microwave-boiled water as compared to that of stove-boiled water. Concludes that within experimental limits, microwave-boiled water and stove-boiled water cool at the same rate. (JRH)

LeMaire, Peter; Waiveris, Charles

1995-01-01

428

Water Molecule Residence Times  

NSDL National Science Digital Library

How long will a molecule of Water stay in a particular reservoir? What is the average time a molecule of Water will stay in an ocean? What is the average time a molecule of water will stay in a river? A lake? As groundwater? A glacier? How long will a water vapor molecule stay suspended in the atmosphere? Why is the residence ...

Science, Sill -.

2010-11-16

429

The Water Cycle  

NSDL National Science Digital Library

The representation is a detailed, labeled diagram of the water cycle. Included in the representation are the major concepts of evaporation, precipitation and ground infiltration, as well as more advanced ideas. Above and below the diagram are several paragraphs that provide an introduction to the water cycle, a quick summary of the parts of the water cycle and information about global water distribution.

430

Waves and Water Beetles  

ERIC Educational Resources Information Center

Capillary and gravity water waves are related to the position, wavelength, and velocity of an object in flowing water. Water patterns are presented for ships and the whirling beetle with an explanation of how the design affects the objects velocity and the observed water wavelengths. (DS)

Tucker, Vance A.

1971-01-01

431

Domestic wash water reclamation  

NASA Technical Reports Server (NTRS)

System consists of filtration unit, reverse-osmosis module, tanks, pumps, plumbing, and various gauges, meters, and valves. After water is used in washing machine or shower, it is collected in holding tank. Water is pumped through series of five particulate filters. Pressure tank supplies processed water to commode water closet.

Hall, J. B., Jr.; Batten, C. E.; Wilkins, J. R.

1974-01-01

432

Water and Something Else.  

ERIC Educational Resources Information Center

Prepared for middle or intermediate grades, this student booklet provides a study of water--the location of major oceans and rivers; the relationship of ancient civilizations to bodies of water; active metals found in sea water; chemical concentrations in water and their effects on marine life; and the concepts of evaporation, transpiration,…

Hougendobler, Nancy

433

Water Exploration Station  

NSDL National Science Digital Library

In this activity (located on page 3 of the PDF), learners investigate the way water moves and how we can control and direct water. At the Water Exploration Station, learners experiment with various tools like eye droppers, sponges, turkey basters, etc. to move and play with the water. Included in this lesson guide are challenge questions intended to direct the learning.

2012-05-09

434

Hold the Water  

ERIC Educational Resources Information Center

Many facilities are considering no-water urinals because they are regarded as an effective way to conserve water. Water must be pumped by electricity, some estimate that as much as $300 per year per urinal can be saved in utility costs. The installation of no-water urinals can help buildings achieve credits toward Leadership in Energy and…

Kravitz, Robert; Reichardt, Klaus

2006-01-01

435

Salt, Water, and Athletes.  

ERIC Educational Resources Information Center

Good nutrition for athletes demands plenty of water, since water is essential to such vital functions as muscle reactions. Dehydration can result from jet travel as well as from exercise and heat, making it a danger to traveling athletic teams. To avoid dehydration, water needs should be monitored by frequent weighing, and a clean water supply…

Smith, Nathan J.

436

Chemistry Review: Water  

NSDL National Science Digital Library

This Review focuses on the many different aspects and states of water. Water is analyzed by its molecular make-up and structure, and the reasons substances dissolve in water are give. Videos and animations are provided to clearly show the set-up of its molecular structure. The relationship between sugar and water molecules are explained in detail, with models as examples.

Kessler, James; Galvan, Patti

2010-01-01

437

Old Water Pump  

USGS Multimedia Gallery

Great Lakes water availability studies conducted by the U.S. Geological Survey aim to help characterize how much water the Basin has now, how water availability is changing, and how much water it can expect to have in the future....

438

Journal of Ground Water  

NSDL National Science Digital Library

Ground Water is a leading technical publication strictly for ground water hydrogeologists. Each issue of the journal contains peer-reviewed scientific articles on pertinent ground water subjects. Non-members can read abstracts, book reviews and software spotlight columns. Members of the National Ground Water Association can view complete articles online.

National Ground Water Association

439

Potable water supply  

NASA Technical Reports Server (NTRS)

The history and evolution of the Apollo potable water system is reviewed. Its operation in the space environment and in the spacecraft is described. Its performance is evaluated. The Apollo potable water system satisfied the dual purpose of providing metabolic water for the crewmen and water for spacecraft cooling.

Sauer, R. L.; Calley, D. J.

1975-01-01

440

Group 8 - Water Pollution  

NSDL National Science Digital Library

BACKGROUND Investigate the issues of water pollution in the world. TASK - What is making the water so polluted? How bad is it? How does nature clean its own water? Who are the worst polluters? What can be done to stop so much pollution? What is the water cycle? What can be done to fix the problem? Explain all this, and 5 ...

Mecham, Mrs.

2006-11-30

441

The Water Filtration Process  

NSDL National Science Digital Library

This demonstration is designed to demonstrate the procedures that municipal water plants use to purify water for drinking. Students will discover that water treatment plants typically clean water by taking it through the processes of aeration, coagulation, sedimentation, filtration, and disinfection. They also learn that water in lakes, rivers, and swamps often contains impurities that make it look and smell bad. The water may also contain bacteria and other microbiological organisms that can cause disease. Consequently, water from surface sources must be cleaned before it can be consumed by people.

442

Wash water recovery system  

NASA Technical Reports Server (NTRS)

The Wash Water Recovery System (WWRS) is intended for use in processing shower bath water onboard a spacecraft. The WWRS utilizes flash evaporation, vapor compression, and pyrolytic reaction to process the wash water to allow recovery of potable water. Wash water flashing and foaming characteristics, are evaluated physical properties, of concentrated wash water are determined, and a long term feasibility study on the system is performed. In addition, a computer analysis of the system and a detail design of a 10 lb/hr vortex-type water vapor compressor were completed. The computer analysis also sized remaining system components on the basis of the new vortex compressor design.

Deckman, G.; Rousseau, J. (editor)

1973-01-01

443

The Water Cycle  

NSDL National Science Digital Library

Did you know that the water we use today is the same water found on Earth millions of years ago? The Earth constantly uses and recycles water in a process called the water cycle. In this lesson, learners explore the four phases of the water cycle. In the investigation Rain in a Jar, learners use hot water and ice to create condensation and a tiny cloud. In Making a Terrarium, learners create an ecosystem and water cycle by growing plants in a closed environment. Investigation spans several days.

2013-12-18

444

Water Resources of Utah  

NSDL National Science Digital Library

This U.S. Geological Survey website provides real-time streamflow, surface-water, ground-water, and water-quality data; information on water resource programs of Utah such as the National Water-Quality Assessment (NAWQA) study; maps and graphs of current U.S. water resource conditions; and USGS - Utah reports. The site also features a drought watch section for Utah containing drought definitions and more streamflow conditions; a section on the Upper Arkansas River Basin Toxic-Substances Hydrology Project; and information on contamination in ground water at Fry Canyon, Utah.

445

The African Water Page  

NSDL National Science Digital Library

Created by Len Abrams, the goal of the African Water Page is to "increase communication on the Continent of Africa between people working in water." Issues for discussion include "water policy, water resource management, water supply and environmental sanitation, water conservation and demand management." Visitors to this page can find information about recent policy initiatives in South Africa, water related documents concerning South Africa, Zimbabwe, the African continent, and some international topics. Also included are links to South and Southern African and International sites.

Abrams, Leonard J.

1995-01-01

446

Irrigation Water Use  

NSDL National Science Digital Library

Part of the USGS Water Science for Schools site, this resource defines irrigation water use and includes several tables and maps showing water use by various irrigation systems, by state, by crop, and by percentage of fresh water available. Students and teachers can look at their state and see 1990 data for how much ground water and how much ground water and surface water is used for irrigation. Various irrigation systems are defined, described, and pictured, along with a discussion of their relative efficiencies. A Spanish translation is available.

2003-05-28

447

PREFACE: Water at interfaces Water at interfaces  

NASA Astrophysics Data System (ADS)

This special issue is devoted to illustrating important aspects and significant results in the field of modeling and simulation of water at interfaces with solutes or with confining substrates, focusing on a range of temperatures from ambient to supercooled. Understanding the behavior of water, in contact with different substrates and/or in solutions, is of pivotal importance for a wide range of applications in physics, chemistry and biochemistry. Simulations of confined and/or interfacial water are also relevant for testing how different its behavior is with respect to bulk water. Simulations and modeling in this field are of particular importance when studying supercooled regions where water shows anomalous properties. These considerations motivated the organization of a workshop at CECAM in the summer of 2009 which aimed to bring together scientists working with computer simulations on the properties of water in various environments with different methodologies. In this special issue, we collected a variety of interesting contributions from some of the speakers of the workshop. We have roughly classified the contributions into four groups. The papers of the first group address the properties of interfacial and confined water upon supercooling in an effort to understand the relation with anomalous behavior of supercooled bulk water. The second group deals with the specific problem of solvation. The next group deals with water in different environments by considering problems of great importance in technological and biological applications. Finally, the last group deals with quantum mechanical calculations related to the role of water in chemical processes. The first group of papers is introduced by the general paper of Stanley et al. The authors discuss recent progress in understanding the anomalies of water in bulk, nanoconfined, and biological environments. They present evidence that liquid water may display 'polymorphism', a property that can be present in other liquids also. Recent evidence of a close relation between thermodynamical properties and dynamical behaviour of water are also discussed. Gallo et al present the results of a computer simulation of water confined in a cylindrical pore of MCM-41 silica material. The mobile portion of the confined water shows a fragile to strong dynamic transition similar to the bulk. In the bound water, an anomalous diffusion connected to the residence time distribution is found. Franzese et al report calculations on lattice models adapted to describe general properties of water in contact with protein surfaces. The results of Monte Carlo and mean field calculations show the presence of two-dynamical crossovers. Corradini et al investigate the supercooled region of ionic aqueous solutions in order to study the effect of ions on the limit of mechanical stability, the lines of maximum density and the liquid-liquid critical point for different ionic concentrations. The paper by Vallauri et al deals with the dynamical behavior of water close to the liquid-liquid transition by considering the velocity correlation functions calculated in three supercooled states. Suffritti et al study water adsorbed in zeolites with a new empirical potential, structural and dynamical properties are studied in the supercooled region. The second group starts with a paper on the problem of solvation by Lynden-Bell. The author shows how the properties of water and, in particular, solvation properties are modified by changes in the site-site interaction potential of water. Henchman et al derive equations for different thermodynamical quantities like partial enthalpy and partial entropy for dilute solutions of noble gases. The third group starts with Buldyrev et al who study the swelling of bead-on-a-string polymers in Jagla water-like particles, finding similarities with respect to cold denaturation of protein in water. Pellenq et al consider water confined in pores of different materials with different size scales. Silicalite and tobermorite, a layered calcio-silicate model of cement and Vycor are anal

Gallo, P.; Rovere, M.

2010-07-01

448

Water use and sustainability  

SciTech Connect

Denver Water is not in a water crisis. They have a conservation program because it is one part of wise water management in this semi-arid region. Denver gets less than 15 inches of precipitation each year, and most of that falls as snow in the winter and spring. In the past, Denver had to depend upon storing the water in reservoirs to ensure a supply during the hot, dry summer. Now, Denver Water also works to reduce water use as a method to extend supplies. There are other benefits as well. When water is used efficiently, more water can remain for recreation, wetlands, dilution, natural aesthetics, and habitat for fish and other wildlife. By extending supplies, protecting the environment and saving money, they all help to ensure a sustainable future. The water conservation team has started a three-year Integrated Resource Planning process based upon a book entitled, `Integrated Resource Planning for Water Utilities`.

Gardener, E.V.; Hernandez, E.L. [Denver Water, CO (United States)

1996-12-31

449

Water Scarcity and Energy: Water and Power Efficiency of  

E-print Network

Water Scarcity and Energy: Water and Power Efficiency of Recycled Water Arizona Hydrological.Eng. Global Water 22 September 2008 #12;Overview · The Finite Nature of Water · Water Availability and Population Growth · Types of Reuse · Water Efficiency of Reuse · Power Efficiency of Reuse #12;Water Scarcity

Scott, Christopher

450

WATER RESOURCES NEWS NEBRASKA WATER RESOURCES RESEARCH INSTITUTE  

E-print Network

of Water Use; (2) Nonpoint Source Pollution; (3) Meeting Water Requirements; (4) Energy-Water Relationships development. (2) Water Pollution and Water Quality Control - Nonpoint Source Pollution Definition: Degradation of water quality from nonpoint source pollution. (3) Water Use Efficiency Definition: Minimize water use

Nebraska-Lincoln, University of

451

National Ground Water Association  

NSDL National Science Digital Library

This web site contains a wealth of information for the groundwater professional and for students of hydrogeology. The site features educational materials, information about conferences, courses and workshops, and a bookstore. There is also a searchable database of abstracts from the journals Ground Water, Ground Water Monitoring Review, Ground Water Monitoring and Remediation, and the Water Well Journal. Members of the National Ground Water Association may access these articles directly. Publications, fact sheets and industry links are also available.

National Ground Water Association

452

The Water Cycle  

NSDL National Science Digital Library

This interactive diagram of the water cycle invites students to click on a part of the cycle to get information about streamflow, surface runoff, freshwater storage, ground-water discharge, ground-water storage, infiltration, precipitation, snowmelt, runoff to streams, springs, condensation, evaporation, transpiration, water in the atmosphere, ice and snow, and oceans. A summary of the water cycle on a single webpage is also available as text with pictures in about fifty languages, text only in thirteen languages, or diagram only.

2007-12-12

453

Ground water and energy  

SciTech Connect

This national workshop on ground water and energy was conceived by the US Department of Energy's Office of Environmental Assessments. Generally, OEA needed to know what data are available on ground water, what information is still needed, and how DOE can best utilize what has already been learned. The workshop focussed on three areas: (1) ground water supply; (2) conflicts and barriers to ground water use; and (3) alternatives or solutions to the various issues relating to ground water. (ACR)

Not Available

1980-11-01

454

Water Treatment Plant  

NSDL National Science Digital Library

In most parts of the United States, getting clean, safe water is as easy as turning on a faucet. Generally, this water comes from either groundwater or nearby streams and reservoirs. What most of us never see or have to worry about are the steps required to make this water drinkable. This video segment, adapted from a ZOOM television broadcast, shows how a water treatment facility in Cambridge, Massachusetts purifies its city's water. The segment is two minutes twenty seconds in length.

455

Water conservation programs  

SciTech Connect

The paper discusses three water conservation programs: statewide water conservation efforts, a 5-point program of the City of Albuquerque, and the program for recycling wastewater by the Intel Corporation. Water conservation programs depend largely on public education programs. Albuquerque`s program, for example, includes development of a K-12th grade curriculum on water conservation, live theater performances promoting conservation for elementary school children, and collaboration with existing community organizations to promote water conservation.

Darilek, A. [New Mexico State Engineer Office, Santa Fe, NM (United States). Water Conservation Program; Witherspoon, J. [City of Albuquerque, NM (United States). Public Works Dept.; Hutchinson, D.L. [Intel Corp., Rio Rancho, NM (United States)

1995-12-31

456

Water Resource Management  

NSDL National Science Digital Library

This portal, published by the University of Florida/Institute of Food and Agricultural Science (IFAS) Extension, offers a selection of links to information about water management issues. There is a 'Beginner's Guide to Water Management', which provides a basic introduction to the terminology and concepts used in water management. Other links access information on management in coastal waters, the impact of climate change on water resources, the use of stormwater as an alternative supply, wastewater management, and many others.

457

Water Treatment Process  

NSDL National Science Digital Library

This interactive diagram allows the user to follow a drop of water from the source through the treatment process. Water may be treated differently in different communities depending on the quality of the water which enters the plant. Groundwater is water located under ground and typically requires less treatment than water from lakes, rivers, and streams. Users are invited to click on each treatment point on the image to see a little information about that treatment point.

458

Water Resources Data, Mississippi, Water Year 2002  

USGS Publications Warehouse

Water resources data for the 2002 water year for Mississippi consist of records of surface water and ground water in the State. Specifically, it contains: (1) Discharge records for 91 streamflow-gaging stations, stage records for 22 of these gaging stations, discharge records for 91 partial-record stations or miscellaneous streamflow sites, including 13 flood hydrograph partial-record stations, 78 crest-stage partial-record stations, and 0 special study and miscellaneous sites; (2) stage only at 9 gaging stations; (3) water-quality records for 13 streamflow-gaging stations, 7 stage-only stations, and 3 water-quality monitor stations, 0 partial-record stations or miscellaneous sites, 97 short-term study sites, and 39 wells; and (4) water-level records for 18 observation wells. Records obtained from water-resources investigations are also included in special sections of the report. These data represent that part of the National Water Data System operated by the U.S. Geological Survey, and cooperating local, State, and Federal agencies in Mississippi.

Morris, F., III; Turnipseed, D.P.; Storm, J.B.

2003-01-01

459

Water Filtration and Purity of Water  

NSDL National Science Digital Library

This lesson, presented by the National Nanotechnology Infrastructure Network, introduces the concept of water purity. In this activity, students will test a sample of water collected from a local water supply and test its purity and evaluate its safety for consumption by looking for pollutants. Before starting, students should have a grasp on how to convert nanoscale measurements. This lab will take two 50 minute classroom sessions. Teacher Preparation Guides, Student Guides, Water Filtration Presentation, and Next Generation Manufacturing Standards for this lesson are included. 

2014-08-12

460

Ground Water and Drinking Water: Frequently Asked Questions (FAQ)  

NSDL National Science Digital Library

This site, from the Office of Ground Water and Drinking Water, presents a list of most frequently asked questions (with answers). Question topics include: drinking water standards, getting information about your tap water and questions about bottled water.

461

OVERVIEW OF USEPA'S WATER SUPPLY & WATER RESOURCES DIVISION PROGRAM  

EPA Science Inventory

The United States Environmental Protection Agency's (USEPA) Water Supply and Water Resources Division (WSWRD) conducts a wide range of research on regulated and unregulated contaminants in drinking water, water distribution systems, homeland security, source water protection, and...

462

Water Microbiology. Bacterial Pathogens and Water  

PubMed Central

Water is essential to life, but many people do not have access to clean and safe drinking water and many die of waterborne bacterial infections. In this review a general characterization of the most important bacterial diseases transmitted through water—cholera, typhoid fever and bacillary dysentery—is presented, focusing on the biology and ecology of the causal agents and on the diseases’ characteristics and their life cycles in the environment. The importance of pathogenic Escherichia coli strains and emerging pathogens in drinking water-transmitted diseases is also briefly discussed. Microbiological water analysis is mainly based on the concept of fecal indicator bacteria. The main bacteria present in human and animal feces (focusing on their behavior in their hosts and in the environment) and the most important fecal indicator bacteria are presented and discussed (focusing on the advantages and limitations of their use as markers). Important sources of bacterial fecal pollution of environmental waters are also briefly indicated. In the last topic it is discussed which indicators of fecal pollution should be used in current drinking water microbiological analysis. It was concluded that safe drinking water for all is one of the major challenges of the 21st century and that microbiological control of drinking water should be the norm everywhere. Routine basic microbiological analysis of drinking water should be carried out by assaying the presence of Escherichia coli by culture methods. Whenever financial resources are available, fecal coliform determinations should be complemented with the quantification of enterococci. More studies are needed in order to check if ammonia is reliable for a preliminary screening for emergency fecal pollution outbreaks. Financial resources should be devoted to a better understanding of the ecology and behavior of human and animal fecal bacteria in environmental waters. PMID:21139855

Cabral, João P. S.

2010-01-01

463

Water microbiology. Bacterial pathogens and water.  

PubMed

Water is essential to life, but many people do not have access to clean and safe drinking water and many die of waterborne bacterial infections. In this review a general characterization of the most important bacterial diseases transmitted through water-cholera, typhoid fever and bacillary dysentery-is presented, focusing on the biology and ecology of the causal agents and on the diseases' characteristics and their life cycles in the environment. The importance of pathogenic Escherichia coli strains and emerging pathogens in drinking water-transmitted diseases is also briefly discussed. Microbiological water analysis is mainly based on the concept of fecal indicator bacteria. The main bacteria present in human and animal feces (focusing on their behavior in their hosts and in the environment) and the most important fecal indicator bacteria are presented and discussed (focusing on the advantages and limitations of their use as markers). Important sources of bacterial fecal pollution of environmental waters are also briefly indicated. In the last topic it is discussed which indicators of fecal pollution should be used in current drinking water microbiological analysis. It was concluded that safe drinking water for all is one of the major challenges of the 21st century and that microbiological control of drinking water should be the norm everywhere. Routine basic microbiological analysis of drinking water should be carried out by assaying the presence of Escherichia coli by culture methods. Whenever financial resources are available, fecal coliform determinations should be complemented with the quantification of enterococci. More studies are needed in order to check if ammonia is reliable for a preliminary screening for emergency fecal pollution outbreaks. Financial resources should be devoted to a better understanding of the ecology and behavior of human and animal fecal bacteria in environmental waters. PMID:21139855

Cabral, João P S

2010-10-01

464

Reactor water cleanup system  

DOEpatents

A reactor water cleanup system includes a reactor pressure vessel containing a reactor core submerged in reactor water. First and second parallel cleanup trains are provided for extracting portions of the reactor water from the pressure vessel, cleaning the extracted water, and returning the cleaned water to the pressure vessel. Each of the cleanup trains includes a heat exchanger for cooling the reactor water, and a cleaner for cleaning the cooled reactor water. A return line is disposed between the cleaner and the pressure vessel for channeling the cleaned water thereto in a first mode of operation. A portion of the cooled water is bypassed around the cleaner during a second mode of operation and returned through the pressure vessel for shutdown cooling. 1 figure.

Gluntz, D.M.; Taft, W.E.

1994-12-20

465

Reactor water cleanup system  

DOEpatents

A reactor water cleanup system includes a reactor pressure vessel containing a reactor core submerged in reactor water. First and second parallel cleanup trains are provided for extracting portions of the reactor water from the pressure vessel, cleaning the extracted water, and returning the cleaned water to the pressure vessel. Each of the cleanup trains includes a heat exchanger for cooling the reactor water, and a cleaner for cleaning the cooled reactor water. A return line is disposed between the cleaner and the pressure vessel for channeling the cleaned water thereto in a first mode of operation. A portion of the cooled water is bypassed around the cleaner during a second mode of operation and returned through the pressure vessel for shutdown cooling.

Gluntz, Douglas M. (San Jose, CA); Taft, William E. (Los Gatos, CA)

1994-01-01

466

Water: Too Precious to Waste.  

ERIC Educational Resources Information Center

Provides background information on many topics related to water. These include the water cycle, groundwater, fresh water, chemical wastes, water purification, river pollution, acid rain, and water conservation. Information is presented at an elementary level. (JM)

National Geographic World, 1983

1983-01-01

467

Incorporating Amino Acid Esters into Catalysts for Hydrogen Oxidation: Steric and Electronic Effects and the Role of Water as a Base  

SciTech Connect

Four derivatives of a hydrogen oxidation catalyst, [Ni(PCy2NBn-R2)]2+ (Cy=cyclohexyl, Bn=benzyl, R= OMe, COOMe, CO-Alanine-methyl ester or CO-Phenylalanine-methyl ester), have been prepared to investigate steric and electronic effects on catalysis. Each complex was characterized spectroscopically and electrochemically, and thermodynamic data were determined. Crystal structures are also reported for the -OMe and -COOMe derivatives. All four catalysts were found to be active for H2 oxidation. The methyl ester (R = COOMe) and amino acid ester containing complexes (R = CO-Alanine-methyl ester or CO-Phenylalanine-methyl ester) had slower rates (4 s-1) than that of the parent complex (10 s-1), in which R = H, consistent with the lower amine pKa’s and less favorable ?GH2’s found for these electron-withdrawing substituents. Dynamic processes for the amino acid ester containing complexes were also investigated and found not to hinder catalysis. The electron-donating methoxy ether derivative (R = OMe) was prepared to compare electronic effects and has a similar catalytic rate as the parent complex. In the course of these studies, it was found that water could act as a weak base for H2 oxidation, although catalytic turnover requires a significantly higher potential and utilizes a different sequence of catalytic steps than when using a base with a higher pKa. Importantly, these catalysts provide a foundation upon which larger peptides can be attached to [Ni(PCy2NBn2)2]2+ hydrogen oxidation catalysts in order to more fully investigate and implement the effects of the outer-coordination sphere. This work was funded by the DOE Office of Science Early Career Research Program through the Office of Basic Energy Sciences (SL and WJS), by the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences (JR), and by the US DOE Basic Energy Sciences, Chemical Sciences, Geoscience and Biosciences Division (AMA, AJ). Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy.

Lense, Sheri; Ho, Ming-Hsun; Chen, Shentan; Jain, Avijita; Raugei, Simone; Linehan, John C.; Roberts, John A.; Appel, Aaron M.; Shaw, Wendy J.

2012-10-08

468

Water quality in sustainable water management  

Microsoft Academic Search

Water pollution is a serious problem as almost 70% of India's surface water resources and a growing number of its groundwater reserves have been contaminated by biological, organic and inorganic pollutants. Pollu - tion of surface and groundwater resources occurs through point and diffuse sources. Examples of point source pollution are effluents from industries and from sewage-treatment plants. Typical examples

Sudhakar M. Rao; P. Mamatha

469

Water, water everywhere, and its remarkable chemistry  

Microsoft Academic Search

Photosystem II (PSII), the multisubunit pigment–protein complex localised in the thylakoid membranes of oxygenic photosynthetic organisms, uses light energy to drive a series of remarkable reactions leading to the oxidation of water. The products of this oxidation are dioxygen, which is released to the atmosphere, and reducing equivalents destined to reduce carbon dioxide to organic molecules. The water oxidation occurs

Jim Barber

2004-01-01

470

Drainage water management for water quality protection  

Technology Transfer Automated Retrieval System (TEKTRAN)

Land drainage has been central to the development of North America since colonial times. Increasingly, agricultural drainage is being targeted as a conduit for pollution, particularly nutrient pollution. The export of agricultural drainage water and associated pollutants to surface water can be mana...

471

Ground Water in Hawaii  

USGS Publications Warehouse

Ground water is one of Hawaii's most important natural resources. It is used for drinking water, irrigation, and domestic, commercial, and industrial needs. Ground water provides about 99 percent of Hawaii's domestic water and about 50 percent of all freshwater used in the State. Total ground water pumped in Hawaii was about 500 million gallons per day during 1995, which is less than 3 percent of the average total rainfall (about 21 billion gallons per day) in Hawaii. From this perspective, the ground-water resource appears ample; however, much of the rainfall runs off to the ocean in streams or returns to the atmosphere by evapotranspiration. Furthermore, ground-water resources can be limited because of water-quality, environmental, or economic concerns. Water beneath the ground surface occurs in two principal zones: the unsaturated zone and the saturated zone. In the unsaturated zone, the pore spaces in rocks contain both air and water, whereas in the saturated zone, the pore spaces are filled with water. The upper surface of the saturated zone is referred to as the water table. Water below the water table is referred to as ground water. Ground-water salinity can range from freshwater to that of seawater. Freshwater is commonly considered to be water with a chloride concentration less than 250 mg/L, and this concentration represents about 1.3 percent of the chloride concentration of seawater (19,500 mg/L). Brackish water has a chloride concentration between that of freshwater (250 mg/L) and saltwater (19,500 mg/L).

Gingerich, Stephen B.; Oki, Delwyn S.

2000-01-01

472

The Management of Water: Water Pollution  

NSDL National Science Digital Library

This is the official water pollution site for Canada. In the introduction, the problem is stated with reference to pollutants of the Great Lakes over 360 chemical compounds have been identified. Many are persistent toxic chemicals - alkylated lead, benzo(a)pyrene, DDT, mercury and mirex - potentially dangerous to humans and already destructive to the aquatic ecosystems. In referring to water quality, pollutants, toxic substances, and acid rain in the aquatic environment are discussed along with long-range transport of airborne pollutants and toxic chemicals said to be the legacy of a chemical society. Efforts to control water pollution include a multi-barrier approach to protecting drinking water, stated water quality objectives and guidelines, regulations, and advice on how to be a responsible consumer. Other sections include the effects of pollution and groundwater pollution.

473

The Water Cycle  

NSDL National Science Digital Library

The representation features a detailed six minute animated lesson about the major processes that move water between land, the ocean and the atmosphere, and convert water between states. Evaporation, condensation, transpiration and water reservoirs are major topics covered by the animation. The portion of the video (05:40 to 06:05 beginning with a drawn scene of mountains, oceans and sky to narration Âdissolved minerals in ground water carried to the ocean for billions of yearsÂ) describes pollutants being filtered out of water while minerals, such as sodium and arsenic, are Âpicked up by the water.

474

Water gas furnace  

SciTech Connect

A water gas furnace comprising an outer container to provide a housing in which coke is placed into its lower part. A water container is placed within the housing. The coke is ignited and heats the water in the container converting it into steam. The steam is ejected into the coke, which together with air, produces water gas. Preferably, pumice stones are placed above the coke. The water gas is accepted into the pores of the pumice stones, where the heated pumice stones ignite the water gas, producing heat. The heat is extracted by a heat exchanger provided about the housing.

Gallaro, C.

1985-12-03

475

Water Resources of Wyoming  

NSDL National Science Digital Library

This U.S Geological Survey (USGS) website contains water data including water quality samples and water use data, information on USGS projects, links to USGS educational sites, and a bibliography of USGS water resource publications. Projects and studies covered include: the Wyoming Drought Watch, which contains maps of daily streamflow conditions and historical streamflow data; algal-nutrient relations in the Yellowstone River; county water resource studies; estimating peak-streamflow characteristics at ungaged sites; the Integrating Aquatic Ecosystem Data project of the Environmental Monitoring and Assessment Program (EMAP); an aquifer; water-quality issues associated with irrigation drainage; watershed delineation; urban hydrology; and a pathogen indicator synoptic study.

476

Water Resources Penn.  

NSDL National Science Digital Library

Water Resources Penn.: The Office of Water Management plans, directs and coordinates departmental programs associated with the management and protection of the CommonwealthÂ?s water resources; administers and oversees departmental programs involving surface and groundwater quantity and quality planning, and soil and water conservation; coordinates policies, procedures and regulations which influence public water supply withdrawals and quality, sewage facilities planning, point source municipal and industrial discharges, encroachments upon waterways and wetlands, dam safety, earth disturbance activities and control of storm water and nonpoint source pollution; and coordinates the planning, design and construction of flood protection and stream improvement projects.

477

Water Illusions: Refraction & Magnification  

NSDL National Science Digital Library

Learners demonstrate how water can distort, refract and magnify light. In an investigation called Underwater Differences, learners do activities including the Broken Pencil, examining how a pencil half-in and half-out of water has its appearance affected by the water, and Stick it to the Bottom, examining how a sticker on a table appears different when seen through a jar of water. In an investigation called Bigger Through Water, learners make a water magnifying loop and use it as a lens to read the newspaper or a magazine. The student journal offers an additional Science @ Home activity about scattering the light from a flashlight.

New Jersey

2006-01-01

478

Predicting Ground Water Flow  

NSDL National Science Digital Library

In this activity students learn how to draw ground water contours and understand how ground water flow may be predicted. As they complete this activity students will be able to draw a ground water contour map, have a basic understanding of how to predict the direction of ground water flow and understand the interrelated nature of ground water and surface water flow. They will also learn the difference between a gaining stream and a losing stream and why it is important to know the difference.

479

Properties of Water  

NSDL National Science Digital Library

Environment Canada (mentioned in the January 21, 1998 Scout Report for Science & Engineering) provides the Properties of Water Webpage. Sections included at the page are the hydrologic cycle; rivers; lakes; snowfall; and measuring, storing, and controlling water, among others. The Quick Facts section contains interesting facts, like the following: raindrops resemble the shape of a hamburger bun, 70% of the human body is water, 75% of earth is covered in water, and most of our food is water (tomatoes 95%, spinach 91%, and beef 61%). This site provides detailed information about water and its properties.

2010-05-20

480

Urban water interfaces  

NASA Astrophysics Data System (ADS)

Urban water systems consist of large-scale technical systems and both natural and man-made water bodies. The technical systems are essential components of urban infrastructure for water collection, treatment, storage and distribution, as well as for wastewater and runoff collection and subsequent treatment. Urban aquatic ecosystems are typically subject to strong human influences, which impair the quality of surface and ground waters, often with far-reaching impacts on downstream aquatic ecosystems and water users. The various surface and subsurface water bodies in urban environments can be viewed as interconnected compartments that are also extensively intertwined with a range of technical compartments of the urban water system. As a result, urban water systems are characterized by fluxes of water, solutes, gases and energy between contrasting compartments of a technical, natural or hybrid nature. Referred to as urban water interfaces, boundaries between and within these compartments are often specific to urban water systems. Urban water interfaces are generally characterized by steep physical and biogeochemical gradients, which promote high reaction rates. We hypothesize that they act as key sites of processes and fluxes with notable effects on overall system behaviour. By their very nature, urban water interfaces are heterogeneous and dynamic. Therefore, they increase spatial heterogeneity in urban areas and are also expected to contribute notably to the temporal dynamics of urban water systems, which often involve non-linear interactions and feedback mechanisms. Processes at and fluxes across urban water interfaces are complex and less well understood than within well-defined, homogeneous compartments, requiring both empirical investigations and new modelling approaches at both the process and system level. We advocate an integrative conceptual framework of the urban water system that considers interfaces as a key component to improve our fundamental understanding of aquatic interface processes in urban environments, advance understanding of current and future system behaviour, and promote an integrated urban water management.

Gessner, M. O.; Hinkelmann, R.; Nützmann, G.; Jekel, M.; Singer, G.; Lewandowski, J.; Nehls, T.; Barjenbruch, M.

2014-06-01

481

It's Your Drinking Water  

MedlinePLUS

... safewater/dwinfo.htm and click on your state. Database: EPA collects information on every public drinking water ... in the nation and stores it in a database called the Safe Drinking Water Information System (SDWIS). ...

482

Electrostatic Water Attraction  

NSDL National Science Digital Library

In this activity, learners conduct a simple experiment to see how electrically charged things like plastic attract electrically neutral things like water. The plastic will attract the surface of the water into a visible bump.

2011-08-20

483

Earth Water Filter  

NSDL National Science Digital Library

In this video segment adapted from ZOOM, cast members try to make the most effective water filter. They experiment with filtering dirty, salty water through different combinations of sand, gravel, and a cotton bandana.

WGBH Educational Foundation

2005-12-17

484

Water Resources Milind Sohoni  

E-print Network

TD 603 Water Resources Milind Sohoni www.cse.iitb.ac.in/sohoni/ Building Numerical Models () August of surface flow of water and infiltration which may include time to flow, movement of solids etc. () August

Sohoni, Milind

485

Society and Water  

ERIC Educational Resources Information Center

At a national symposium on Societal Problems of Water Resources at Western Illinois University, scientists discussed dams, canals, water pollution control and management programs, federal-state relations in resource planning, and their effects on how we live. (BL)

Qutub, Musa Y.

1972-01-01