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1

Nanostructured Titanium Oxide Film- And Membrane-Based Photocatalysis For Water Treatment  

EPA Science Inventory

Titanium Oxide (TiO2) photocatalysis, one of the ultraviolet (UV)-based advanced oxidation technologies (AOTs) and nanotechnologies (AONs), has attracted great attention for the development of efficient water treatment and purification systems due to the effectiveness ...

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

2013-03-04

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

High concentrated phenol and 1,2-propylene glycol water solutions treatment by photocatalysis  

Microsoft Academic Search

The degradation of high phenol and 1,2-propylene glycol concentrations (1g\\/l) in water solutions by TiO2-photocatalysis has been studied. Important differences between the degradation mechanism of both molecules have been observed. From the obtained data it may be suggested that degradation of phenol takes place onto the catalyst surface by means of formation of peroxo-compounds. At low phenol concentrations another mechanism,

J. Araña; E. Tello Rendón; J. M. Doña Rodr??guez; J. A. Herrera Melián; O. González D??az; J. Pérez Peña

2001-01-01

5

Photocatalysis for the treatment of waste water: Applications involving the removal of metals  

Microsoft Academic Search

This paper describes laboratory work investigating the applicability of solar-powered photocatalysis for the treatment of water contaminated with heavy metals and organics. It was found that Ag(I), Au (HI), Cr(VI), Hg(H), Pd(H), and PT(IV) are easily treated while Cd(U), Cu(II), and NI(II) are not. The importance of the entire photocatalytic redox cycle is demonstrated by showing that the rates of

M. R. Prairie; B. M. Stange

1993-01-01

6

Developments in solar photocatalysis for destruction of organics in water  

Microsoft Academic Search

We are developing a process that has the potential to destroy a wide range of organic contaminants in water using solar energy and a titanium dioxide photocatalyst, TiOâ. Contaminated water flows through a reactor on which sunlight is focused to activate the catalyst forming hydroxyl radicals and super oxide ions. These reactive species readily attack and decompose organics in solution

J. E. Pacheco; C. Carwile; K. A. Magrini; M. Mehos

1989-01-01

7

Solar photocatalysis—a possible step in drinking water treatment  

Microsoft Academic Search

Possibility of the use of solar radiation for reduction of Natural Organic Matter (NOM) content in natural lake water, as a source for drinking water preparation, was the topic of this research. Solar radiation alone does not have enough energy for sufficient degradation of NOM, but in combination with heterogeneous photocatalyst-titanium dioxide (TiO2), with or without other chemicals, the degradation

Davor Ljubas

2005-01-01

8

Degradation of X-3B dye by immobilized TiO 2 photocatalysis coupling anodic oxidation on BDD electrode  

Microsoft Academic Search

Photocatalysis on nano-sized TiO2 and electrocatalysis on boron-doped diamond (BDD) electrode, all belonged to advanced oxidation processes (AOPs) in the field of wastewater treatment, were united into one batch reactor in our experiments. Reactive brilliant red X-3B dye was used as model compound to study the combinatory effect between photocatalysis and electrocatalysis. The titania sol, deposited on glass substrate, prepared

Chunyong Zhang; Linjuan Gu; Yihua Lin; Yongxiang Wang; Degang Fu; Zhongze Gu

2009-01-01

9

Developments in solar photocatalysis for destruction of organics in water  

SciTech Connect

We are developing a process that has the potential to destroy a wide range of organic contaminants in water using solar energy and a titanium dioxide photocatalyst, TiO{sub 2}. Contaminated water flows through a reactor on which sunlight is focused to activate the catalyst forming hydroxyl radicals and super oxide ions. These reactive species readily attack and decompose organics in solution producing only water, CO{sub 2} and halo acids. Tests have been conducted at three levels: at a benchtop scale (liter), with a small outdoor trough (100 liters) and with a large outdoor parabolic trough (2000 liters). The experimental variables examined include ultraviolet light intensity, catalyst loading, the effect of adding hydrogen peroxide, and the performance of catalyst supports. The intensity of ultraviolet irradiation significantly affected decomposition rates of a chlorinated solvent, trichloroethylene (TCE) yielding faster reaction rates at higher intensities. The amount of catalyst in suspension affected the destruction rate of trichloroethylene; the rate increased as the amount of catalyst was increased from 0.01 to 0.1 wt%. Hydrogen peroxide used in conjunction with TiO{sub 2} significantly enhanced the photocatalytic decomposition rate of a model compound, salicylic acid, by as much as 8 times over the rate with TiO{sub 2} alone. Supported TiO{sub 2} on silica glass beads performed less effectively compared to suspended TiO{sub 2} for TCE decomposition with simulated sunlight as did TiO{sub 2} on alumina ceramic frits for decomposing salicylic acid in natural sunlight. TiO{sub 2} on fiberglass mesh performed about as well as the ceramic frits. 20 refs., 10 figs., 1 tab.

Pacheco, J.E. (Sandia National Labs., Albuquerque, NM (USA)); Carwile, C. (USDOE, Washington, DC (USA)); Magrini, K.A.; Mehos, M. (Solar Energy Research Inst., Golden, CO (USA))

1989-01-01

10

Inactivation and injury of total coliform bacteria after primary disinfection of drinking water by TiO2 photocatalysis.  

PubMed

In this study the potential application of TiO(2) photocatalysis as primary disinfection system of drinking water was investigated in terms of coliform bacteria inactivation and injury. As model water the effluent of biological denitrification unit for nitrate removal from groundwater, which is characterized by high organic matter and bacteria release, was used. The injury of photocatalysis on coliform bacteria was characterized by means of selective (mEndo) and less selective (mT7) culture media. Different catalyst loadings as well as photolysis and adsorption effects were investigated. Photocatalysis was effective in coliform bacteria inactivation (91-99% after 60 min irradiation time, depending on both catalyst loading and initial density of coliform bacteria detected by mEndo), although no total removal was observed after 60 min irradiation time. The contribution of adsorption mechanism was significant (60-98% after 60 min, depending on catalyst loading) compared to previous investigations probably due to the nature of source water rich in particulate organic matter and biofilm. Photocatalysis process did not result in any irreversible injury (98.8% being the higher injury) under investigated conditions, thus a bacteria regrowth may take place under optimum environment conditions if any final disinfection process (e.g., chlorine or chlorine dioxide) is not used. PMID:18990490

Rizzo, Luigi

2008-09-26

11

Photocatalysis for the treatment of waste water: Applications involving the removal of metals  

SciTech Connect

This paper describes laboratory work investigating the applicability of solar-powered photocatalysis for the treatment of water contaminated with heavy metals and organics. It was found that Ag(I), Au (HI), Cr(VI), Hg(H), Pd(H), and PT(IV) are easily treated while Cd(U), Cu(II), and NI(II) are not. The importance of the entire photocatalytic redox cycle is demonstrated by showing that the rates of oxidation (of organics) and reduction (of metals) are intrinsically interrelated. Data are presented showing that photoefficiency decreases as light intensity increases in the range of 0 to 17 suns UV. This result suggests that one-sun systems are more efficient than those using concentrated solar radiation. Preliminary data for three samples of actual waste: (1) gold mining leachate, (2) precious metals mining extract, and (3) photographic waste, are described. In general, actual applications are less effective than predicted using laboratory data for clean systems.

Prairie, M.R.; Stange, B.M.

1993-01-01

12

Photocatalysis for the treatment of waste water: Applications involving the removal of metals  

SciTech Connect

This paper describes laboratory work investigating the applicability of solar-powered photocatalysis for the treatment of water contaminated with heavy metals and organics. It was found that Ag(I), Au (HI), Cr(VI), Hg(H), Pd(H), and PT(IV) are easily treated while Cd(U), Cu(II), and NI(II) are not. The importance of the entire photocatalytic redox cycle is demonstrated by showing that the rates of oxidation (of organics) and reduction (of metals) are intrinsically interrelated. Data are presented showing that photoefficiency decreases as light intensity increases in the range of 0 to 17 suns UV. This result suggests that one-sun systems are more efficient than those using concentrated solar radiation. Preliminary data for three samples of actual waste: (1) gold mining leachate, (2) precious metals mining extract, and (3) photographic waste, are described. In general, actual applications are less effective than predicted using laboratory data for clean systems.

Prairie, M.R.; Stange, B.M.

1993-04-01

13

Solar photocatalysis for detoxification and disinfection of water: Different types of suspended and fixed TiO 2 catalysts study  

Microsoft Academic Search

Photocatalysis by titanium dioxide (TiO2), operational in the UV-A domain with a potential use of solar radiation, could be an alternative to conventional water detoxification and disinfection technologies. However, employing the photocatalyst as a suspension or slurry makes the scaling-up of the process difficult, as the TiO2 has to be removed from the decontaminated water to be reused several times.

D. Gumy; A. G. Rincon; R. Hajdu; C. Pulgarin

2006-01-01

14

Studies on various reactor configurations for coupling photocatalysis and membrane processes in water purification  

Microsoft Academic Search

General aspects and perspectives of heterogeneous photocatalysis for the treatment of polluted aqueous effluents are presented. Some experimental results obtained by using various configurations of photocatalytic membrane reactors (PMRs) are reported. The configurations studied were: (i) irradiation of the cell containing the membrane, with three sub-cases: (i1) catalyst deposited on the membrane; (i2) catalyst in suspension, confined by means of

Raffaele Molinari; Leonardo Palmisano; Enrico Drioli; Mario Schiavello

2002-01-01

15

Decontamination and disinfection of water by solar photocatalysis: Recent overview and trends  

Microsoft Academic Search

In recent years, there has been a tremendous amount of research and development in the area of photocatalysis (heterogeneous and homogeneous), a process included in a special class of oxidation techniques defined as Advanced Oxidation Processes (AOPs), all characterized by the same chemical feature, production of OH radicals. This paper reviews the use of sunlight to produce the OH radicals

S. Malato; P. Fernández-Ibáñez; M. I. Maldonado; J. Blanco; W. Gernjak

2009-01-01

16

Electrocatalysis for Oxygen Electrodes in Fuel Cells and Water Electrolyzers for Space Applications.  

National Technical Information Service (NTIS)

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 g...

J. Prakash D. Tryk E. Yeager

1989-01-01

17

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

2013-07-12

18

Dimethylformamide-mediated synthesis of water-soluble platinum nanodendrites for ethanol oxidation electrocatalysis.  

PubMed

Herein we describe the synthesis of water-soluble platinum nanodendrites in dimethylformamide (DMF), in the presence of polyethyleneimine (PEI) as a stabilizing agent. The average size of the dendrites is in the range of 20-25 nm while their porosity can be tuned by modifying the concentration of the metal precursor. Electron tomography revealed different crystalline orientations of nanocrystallites in the nanodendrites and allowed a better understanding of their peculiar branching and porosity. The high surface area of the dendrites (up to 22 m(2) g(-1)) was confirmed by BET measurements, while X-ray diffraction confirmed the abundance of high-index facets in the face-centered-cubic crystal structure of Pt. The prepared nanodendrites exhibit excellent performance in the electrocatalytic oxidation of ethanol in alkaline solution. Sensing, selectivity, cycleability and great tolerance toward poisoning were demonstrated by cyclic voltammetry measurements. PMID:23613112

Mourdikoudis, Stefanos; Chirea, Mariana; Altantzis, Thomas; Pastoriza-Santos, Isabel; Pérez-Juste, Jorge; Silva, Fernando; Bals, Sara; Liz-Marzán, Luis M

2013-04-23

19

Solar light assisted photocatalysis of water using a zinc oxide semiconductor  

NASA Astrophysics Data System (ADS)

The photocatalytic decomposition of an eco-persistent AO7 dye with sunlight in an oxygenated aqueous suspension has been studied under a nano-crystalline hexagonal ZnO photocatalyst. The effect of substrate temperature on the structural, morphological and photoactive properties has been investigated. The degradation of the AO7 dye is achieved using a photoelectrochemical reactor module equipped with ZnO synthesized electrodes. Kinetic parameters have been investigated in terms of a first order rate equation. The rate constant for this heterogeneous photocatalysis was evaluated as a function of the initial concentration of original species. A substantial reduction in AO7 dye is achieved as analyzed from COD and TOC studies. The mechanism for the degradation could be explained on the basis of the Langmuir-Hinshelwood mechanism.

Shinde, S. S.; Bhosale, C. H.; Rajpure, K. Y.

2013-04-01

20

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

NASA Astrophysics Data System (ADS)

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

1989-12-01

21

Solar photocatalysis for treatment of Acid Yellow-17 (AY-17) dye contaminated water using Ag@TiO2 core-shell structured nanoparticles.  

PubMed

Wastewater released from textile industries causes water pollution, and it needs to be treated before discharge to the environment by cost effective technologies. Solar photocatalysis is a promising technology for the treatment of dye wastewater. The Ag@TiO2 nanoparticles comprising of Ag core and TiO2 shell (Ag@TiO2) have unique photocatalytic property of inhibition of electron-hole recombination and visible light absorption, which makes it a promising photocatalyst for use in solar photocatalysis and with higher photocatalytic rate. Therefore, in the present work, the Ag@TiO2 nanoparticles synthesized by one pot method with postcalcination step has been used for the degradation of Acid Yellow-17 (AY-17) dye under solar light irradiation. The Ag@TiO2 nanoparticles were characterized using thermogravimetric-differential thermal analysis, X-ray diffraction, transmission electron microscopy, selected area electron diffraction, and energy dispersive X-ray analysis. The catalyst has been found to be very effective in solar photocatalysis of AY-17, as compared to other catalysts. The effects of pH, catalyst loading, initial dye concentration, and oxidants on photocatalysis were also studied. The optimized parameters for degradation of AY-17 using Ag@TiO2 were found to be pH?3, dye/catalyst ratio of 1:10 (g/g), and 2 g/L of (NH4)2S2O8 as oxidant. Efficient decolorization and mineralization of AY-17 was achieved. The kinetics of color, total organic carbon, and chemical oxygen demand removal followed the Langmuir-Hinshelwood model. Ag@TiO2 catalyst can be reused thrice without much decline in efficiency. The catalyst exhibited its potential as economic photocatalyst for treatment of dye wastewater. PMID:23463278

Khanna, Ankita; Shetty K, Vidya

2013-03-06

22

The effect of operational parameters on electrocoagulation-flotation process followed by photocatalysis applied to the decontamination of water effluents from cellulose and paper factories.  

PubMed

Cellulose and paper pulp factories utilize a large amount of water generating several undesirable contaminants. The present work is a preliminary investigation that associates the electrocoagulation-flotation (EC) method followed by photocatalysis to treat such wastewater. For EC, the experiment with aluminium and iron electrodes showed similar efficiency. Iron electrodes (anode and cathode) were chosen. By applying 30min of EC/Fe(0), 153A m(-2) and pH 6.0, the COD values, UV-vis absorbance and turbidity underwent an intense decrease. For the subsequent UV photocatalysis (mercury lamps) TiO(2) was employed and the favourable operational conditions found were 0.25g L(-1) of the catalyst and solution pH 3.0. The addition of hydrogen peroxide (50mmol L(-1)) highly increased the photo-process performance. By employing the UV/TiO(2)/H(2)O(2) system, the COD reduction was 88% compared to pre-treated effluents and complete sample photobleaching was verified. The salt concentration on EC (iron electrodes) showed that the electrolysis duration can be reduced from 30 to 10min by the addition of 5.0g L(-1) of NaCl. The biodegradability index (BOD/COD) increased from 0.15 (pre-treated) to 0.48 (after EC) and to 0.89 (after EC/photocatalysis irradiated for 6h), showing that the employed sequence is very helpful to improve the water quality. This result was confirmed by biotoxicity tests performed with microcrustaceous Artemia salina. PMID:18417286

Boroski, Marcela; Rodrigues, Angela Cláudia; Garcia, Juliana Carla; Gerola, Adriana Passarella; Nozaki, Jorge; Hioka, Noboru

2008-03-02

23

Low-temperature synthesis of water-dispersible anatase titanium dioxide nanoparticles for photocatalysis.  

PubMed

Water-dispersible anatase TiO2 nanoparticles were synthesized at a low temperature (80°C) without using surfactants via the mechanism of electrostatic stabilization. The water-dispersible TiO2 nanoparticles solution was stable and no precipitation occurred after 3months. Photocatalytic evaluation demonstrated that the as-synthesized TiO2 nanoparticles possess excellent quinoline degradation performance (a 2.33×10(-2)min(-1) apparent reaction rate constant comparing to 1.22×10(-2)min(-1) for P25) and recycle stability (the photocatalytic activity remained 96.6% of the initial activity after four cycles of repetitive uses). These could be attributed to the small size and good water-dispersibility of the as-synthesized TiO2 nanoparticles that led to large specific surface area and easy photogenerated electron-hole transportation. PMID:23407148

Jing, Jieying; Feng, Jie; Li, Wenying; Yu, William W

2013-01-25

24

Arsenic removal from water employing heterogeneous photocatalysis with TiO2 immobilized in PET bottles.  

PubMed

Arsenic oxidation (As(III) to As(V)) and As(V) removal from water were assessed by using TiO2 immobilized in PET (polyethylene terephthalate) bottles in the presence of natural sunlight and iron salts. The effect of many parameters was sequentially studied: TiO2 concentration of the coating solution, Fe(II) concentration, pH, solar irradiation time; dissolved organic carbon concentration. The final conditions (TiO2 concentration of the coating solution: 10%; Fe(II): 7.0 mg l(-1); solar exposure time: 120 min) were applied to natural water samples spiked with 500 microg l(-1) As(III) in order to verify the influence of natural water matrix. After treatment, As(III) and total As concentrations were lower than the limit of quantitation (2 microg l(-1)) of the voltammetric method used, showing a removal over 99%, and giving evidence that As(III) was effectively oxidized to As(V). The results obtained demonstrated that TiO2 can be easily immobilized on a PET surface in order to perform As(III) oxidation in water and that this TiO2 immobilization, combined with coprecipitation of arsenic on Fe(III) hydroxides(oxides) could be an efficient way for inorganic arsenic removal from groundwaters. PMID:18342358

Fostier, Anne Hélène; Pereira, Maria do Socorro Silva; Rath, Susanne; Guimarães, José Roberto

2008-03-14

25

Arsenic removal from water employing heterogeneous photocatalysis with TiO 2 immobilized in PET bottles  

Microsoft Academic Search

Arsenic oxidation (As(III) to As(V)) and As(V) removal from water were assessed by using TiO2 immobilized in PET (polyethylene terephthalate) bottles in the presence of natural sunlight and iron salts. The effect of many parameters was sequentially studied: TiO2 concentration of the coating solution, Fe(II) concentration, pH, solar irradiation time; dissolved organic carbon concentration. The final conditions (TiO2 concentration of

Anne Hélène Fostier; Maria do Socorro Silva Pereira; Susanne Rath; José Roberto Guimarães

2008-01-01

26

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

27

Doping metal-organic frameworks for water oxidation, carbon dioxide reduction, and organic photocatalysis.  

PubMed

Catalytically competent Ir, Re, and Ru complexes H(2)L(1)-H(2)L(6) with dicarboxylic acid functionalities were incorporated into a highly stable and porous Zr(6)O(4)(OH)(4)(bpdc)(6) (UiO-67, bpdc = para-biphenyldicarboxylic acid) framework using a mix-and-match synthetic strategy. The matching ligand lengths between bpdc and L(1)-L(6) ligands allowed the construction of highly crystalline UiO-67 frameworks (metal-organic frameworks (MOFs) 1-6) that were doped with L(1)-L(6) ligands. MOFs 1-6 were isostructural to the parent UiO-67 framework as shown by powder X-ray diffraction (PXRD) and exhibited high surface areas ranging from 1092 to 1497 m(2)/g. MOFs 1-6 were stable in air up to 400 °C and active catalysts in a range of reactions that are relevant to solar energy utilization. MOFs 1-3 containing [Cp*Ir(III)(dcppy)Cl] (H(2)L(1)), [Cp*Ir(III)(dcbpy)Cl]Cl (H(2)L(2)), and [Ir(III)(dcppy)(2)(H(2)O)(2)]OTf (H(2)L(3)) (where Cp* is pentamethylcyclopentadienyl, dcppy is 2-phenylpyridine-5,4'-dicarboxylic acid, and dcbpy is 2,2'-bipyridine-5,5'-dicarboxylic acid) were effective water oxidation catalysts (WOCs), with turnover frequencies (TOFs) of up to 4.8 h(-1). The [Re(I)(CO)(3)(dcbpy)Cl] (H(2)L(4)) derivatized MOF 4 served as an active catalyst for photocatalytic CO(2) reduction with a total turnover number (TON) of 10.9, three times higher than that of the homogeneous complex H(2)L(4). MOFs 5 and 6 contained phosphorescent [Ir(III)(ppy)(2)(dcbpy)]Cl (H(2)L(5)) and [Ru(II)(bpy)(2)(dcbpy)]Cl(2) (H(2)L(6)) (where ppy is 2-phenylpyridine and bpy is 2,2'-bipyridine) and were used in three photocatalytic organic transformations (aza-Henry reaction, aerobic amine coupling, and aerobic oxidation of thioanisole) with very high activities. The inactivity of the parent UiO-67 framework and the reaction supernatants in catalytic water oxidation, CO(2) reduction, and organic transformations indicate both the molecular origin and heterogeneous nature of these catalytic processes. The stability of the doped UiO-67 catalysts under catalytic conditions was also demonstrated by comparing PXRD patterns before and after catalysis. This work illustrates the potential of combining molecular catalysts and MOF structures in developing highly active heterogeneous catalysts for solar energy utilization. PMID:21780787

Wang, Cheng; Xie, Zhigang; deKrafft, Kathryn E; Lin, Wenbin

2011-08-05

28

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

NASA Astrophysics Data System (ADS)

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 N2 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 m2/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.

Suo, Zhirong; Dong, Xiaonan; Liu, Hui

2013-10-01

29

Nanomaterials for Sensing and Electrocatalysis  

SciTech Connect

This special issue provides an overview of recent advances in nanomaterials for sensing and electrocatalysis. The emergence of nanoscience and nanotechnology has led to great advances in electrochemical science and technology, and these advances may lead to a new branch of electrochemistry research-electrochemical nanotechnology-that combines electrochemical techniques with nanotechnologies to address important issues in energy, electronics, environment, and heath care.

Li, Jinghong; Lin, Yuehe

2009-04-01

30

Electrocatalysis with vitamin B sub 12 in water-in-oil microemulsions at carbon-fiber microelectrodes  

SciTech Connect

Microemulsions are clear, thermodynamically stable dispersions containing oil, surfactant and water. They are crude models of biological membranes and can be used to investigate some of the organizational influence of membranes in lipid and protein synthesis, energy transduction, ion and group transport, etc. This thesis concerns the investigation of microemulsion properties as media in which catalytic reduction of vicinal dibromides can take place with the electrochemically generated Co(I) form of Vitamin B{sub 12}. Methods to study fundamental properties of resistive w/o AOT/H{sub 2}O/isoctane were developed. Microelectrodes of approximate radius of 6 {mu}m were prepared and characterized. Nonlinear regression was applied to the analysis of steady state voltammograms obtained at carbon-fiber microelectrodes. Reversible regression models were used to analyze data for oxidation of ferrocene in acetonitrile with and without added electrolyte. An estimate of cell resistance in highly resistive media was obtained by including ohmic drop in the model for reversible electron transfer. The electrocatalytic reduction of 1,2-dibromoethane (EDB), 1,2-dibromobutane (DBB), and trans-1,2-dibromocyclohexane (DBCH) with Vitamin B{sub 12} in pH {le} 3 water MeCN and w/o microemulsions of AOT/H{sub 2}O/isoctane at carbon fiber microelectrode was investigated. The microviscosity of w/o microemulsions were estimated from the Stokes-Einstein equation using ferrocene as a probe. Results show that the diffusion of molecules in the microemulsions are similar to their diffusion in organic phase (isoctane). Nonlinear regression analysis of the data for AOT w/o microemulsions describing the dependence of D{prime} on C{sub x} enables an estimate of micelle diffusion coefficients.

Owlia, A.

1989-01-01

31

Assessment of solar photocatalysis to purify on-site rinse waters from tractor cisterns used in grapevine pest control: field experimentation.  

PubMed

The aim of this study was to assess in a vineyard the effect of purifying by solar photocatalysis the title rinse waters (currently most often rejected) in terms of efficacy and on-site practicality for the wine grower. The on-site, self-functioning, solar purifying unit included a corrugated-steel inclined plate of area S = 1 m2 onto which a TiO2-coated thin material had been slightly pressed, a tank, and an aquarium-type pump powered by a photovoltaic panel (appropriate for isolated locations). For a vineyard of area A = 0.15 km2, the rinse water (about 90 L) corresponding to each of four typical vine treatments in summer was analysed (major pesticides for each treatment, TOC, Microtox test and, in one case, BOD5) by independent laboratories, before and after purification for 8 days. The S/A ratio tested was found insufficient even if the photocatalytic treatment markedly improved the quality of the rinse waters. From the relatively low final organic content reached in one case, it is calculated that a three-time higher S/A ratio might suffice, but new trials are necessary to determine whether it is valid for other typical cases. Inferred contribution of inorganic ions to the post-photocatalytic treatment toxicity points to the need for an additional detoxification. These field experiments have also demonstrated that the purifying prototype is robust, and easy to install and use on site by the wine grower. PMID:16312971

Pichat, P; Vannier, S; Dussaud, J; Rubis, J P

2005-01-01

32

Semiconductor photocatalysis--mechanistic and synthetic aspects.  

PubMed

Preceding work on photoelectrochemistry at semiconductor single-crystal electrodes has formed the basis for the tremendous growth in the three last decades in the field of photocatalysis at semiconductor powders. The reason for this is the unique ability of inorganic semiconductor surfaces to photocatalyze concerted reduction and oxidation reactions of a large variety of electron-donor and -acceptor substrates. Whereas great attention was paid to water splitting and the exhaustive aerobic degradation of pollutants, only a small amount of research also explored synthetic aspects. After introducing the basic mechanistic principles, standard experiments for the preparation and characterization of visible light active photocatalysts as well as the investigation of reaction mechanisms are discussed. Novel atom-economic C-C and C-N coupling reactions illustrate the relevance of semiconductor photocatalysis for organic synthesis, and demonstrate that the multidisciplinary field combines classical photochemistry with electrochemistry, solid-state chemistry, and heterogeneous catalysis. PMID:23212748

Kisch, Horst

2012-12-04

33

Anion Bridging and Anion Electrocatalysis on Mercury.  

National Technical Information Service (NTIS)

The evidence for the existence of anion bridging and anion electrocatalysis on mercury electrodes is reviewed. It is shown to be a rather common mechanism. Its elucidation often requires accurate surface activity data. Some difficulties in obtaining the l...

R. de Levie

1971-01-01

34

Inactivation of Staphylococcus aureus and Escherichia coli in Water Using Photocatalysis with Fixed TiO 2  

Microsoft Academic Search

Photocatalytic activity in titanium dioxide (TiO2) has been extensively studied because of its potential use in sterilization, sanitation, and remediation applications. The\\u000a aim of the study reported here was to assess the feasibility of “fixed” TiO2 as the photocatalyst for inactivating pathogenic bacteria selected, Staphylococcus aureus and Escherichia coli, from a water stream. The investigation was undergone in a properly

Chih-Yu Chen; Li-Chun Wu; Hsuan-Yu Chen; Ying-Chien Chung

2010-01-01

35

Nano-NiO as a photocatalyst in antimicrobial activity of infected water using laser induced photo-catalysis  

Microsoft Academic Search

Nano NiO photo catalyst was synthesized by sol gel method and it is used as a photo catalyst in conjunction with 355 nm laser radiation in the process of disinfecting water infected with Escherichia coli microorganism. When synthesized nano-NiO material is used as a photo catalyst, a bacteria decay rate constant of 0.35 min-1 and this rate constant is higher

M. A. Gondal; M. A. Dastageer; A. Khalil

2011-01-01

36

The stability of polymeric membranes in a TiO 2 photocatalysis process  

Microsoft Academic Search

The coupling of photocatalysis with membrane separation has emerged as a promising water treatment process. This study focuses on the selection of polymeric membranes for the photocatalytic-membrane process. Ten membranes were evaluated under ultraviolet (UV) and TiO2 photocatalysis conditions. Membrane stability was characterized by changes in pure water flux (PWF), release of total organic carbon (TOC) and scanning electron microscope

Sze Sze Chin; Ken Chiang; Anthony Gordon Fane

2006-01-01

37

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

38

First principles simulations of materials and processes in photo- and electro-catalysis  

NASA Astrophysics Data System (ADS)

I shall discuss applications of electronic structure calculations and molecular dynamics simulations to understand materials properties and reaction mechanisms in photo- and electro-catalysis. Examples will include studies of the interface between water and titanium dioxide (TiO2), a widely used photocatalyst capable of splitting water in O2 + H2, and the cycle of H2 production from water by the active site of an enzyme of hydrogen-producing bacteria, the di-iron hydrogenase, linked to a pyrite electrode.

Selloni, Annabella

2011-03-01

39

Removal of aqueous chromate [Cr(VI)] through photocatalysis by using TiO2-coated silica granules  

Microsoft Academic Search

The aim of this study was to determine the optimal conditions for the treatment of chromate [Cr(VI)]- contaminated water by UV photocatalysis using synthesized TiO2-coated silica granules (? 1.7–4.0 mm) containing 12.4% of TiO2 in a batch method. The effect of the volume of the solution on Cr(VI) removal was investigated in the photocatalysis process by using 10 g of

Kazutoshi Saeki; Mayumi Kadono; Akiko Nabeshima

2010-01-01

40

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

41

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.

1993-06-01

42

Microfluidic photoelectrocatalytic reactors for water purification with an integrated visible-light source.  

PubMed

This paper reports experimental studies using the photoelectrocatalytic effect to eliminate a fundamental limit of photocatalysis - the recombination of photo-excited electrons and holes. The fabricated reactor has a planar reaction chamber (10 × 10 × 0.1 mm(3)), formed by a blank indium tin oxide glass slide, an epoxy spacer and a BiVO(4)-coated indium tin oxide glass substrate. A blue light-emitting diode panel (emission area 10 × 10 mm(2)) is mounted on the cover for uniform illumination of the reaction chamber. In the experiment, positive and negative bias potentials were applied across the reaction chamber to suppress the electron/hole recombination and to select either the hole-driven or electron-driven oxidation pathway. The negative bias always exhibits higher performance. It is observed that under -1.8 V the degradation rate is independent of the residence time, showing that the accompanying electrolysis can solve the oxygen deficiency problem. The synergistic effect of photocatalysis and electrocatalysis is observed to reach its maximum under the bias potential of ± 1.5 V. The photoelectrocatalytic microreactor shows high stability and may be scaled up for high-performance water purification. PMID:22930198

Wang, Ning; Zhang, Xuming; Chen, Bolei; Song, Wuzhou; Chan, Ngai Yui; Chan, Helen L W

2012-10-21

43

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...

44

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...

45

Particle size and support effects in electrocatalysis.  

PubMed

Researchers increasingly recognize that, as with standard supportedheterogeneous catalysts, the activity and selectivity of supported metal electrocatalysts are influenced by particle size, particle structure, and catalyst support. Studies using model supported heterogeneous catalysts have provided information about these effects. Similarly, model electrochemical studies on supported metal electrocatalysts can provide insight into the factors determining catalytic activity. High-throughput methods for catalyst synthesis and screening candetermine systematic trends in activity as a function of support and particle size with excellent statistical certainty. In this Account, we describe several such studies investigating methods for dispersing precious metals on both carbon and oxide supports, with particular emphasis on the prospects for the development of low-temperature fuel-cell electrocatalysts. One key finding is a decrease in catalytic activity with decreasing particle size independent of the support for both oxygen reduction and CO oxidation on supported gold and platinum. For these reactions, there appears to be an intrinsic particle size effect that results in a loss of activity at particle sizes below 2-3 nm. A titania support, however, also increases activity of gold particles in the electrooxidation of CO and in the reduction of oxygen, with an optimum at 3 nm particle size. This optimum may represent the superposition of competing effects: a titania-induced enhanced activity versus deactivation at small particle sizes. The titania support shows catalytic activity at potentials where carbon-supported and bulk-gold surfaces are normally oxidized and CO electrooxidation is poisoned. On the other hand, platinum on amorphous titania shows a different effect: the oxidation reduction reaction is strongly poisoned in the same particle size range. We correlated the influence of the titania support with titania-induced changes in the surface redox behavior of the platinum particles. For both supported gold and platinum particles in electrocatalysis, we observe parallels to the effects of particle size and support in the equivalent heterogeneous catalysts. Studies of model supported-metal electrocatalysts, performs efficiently using high throughput synthetic and screening methodologies, will lead to a better understanding of the mechanisms responsible for support and particle size effects in electrocatalysis, and will drive the development of more effective and robust catalysts in the future. PMID:23719578

Hayden, Brian E

2013-05-29

46

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

47

Electrocatalysis of anodic and cathodic oxygen-transfer reactions.  

National Technical Information Service (NTIS)

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 ...

B. R. Wels

1990-01-01

48

Bifunctional photocatalysis of TiO2/Cu2O composite under visible light: Ti3+ in organic pollutant degradation and water splitting  

NASA Astrophysics Data System (ADS)

Photocatalytic experiment results under visible light demonstrate that both TiO2 and Cu2O have low activity for brilliant red X-3B degradation and neither can produce H2 from water splitting. In comparison, TiO2/Cu2O composite can do the both efficiently. Further investigation shows that the formation of Ti3+ under visible light has great contribution. The mechanism of photocatalytic reaction is proposed based on energy band theory and experimental results. The photogenerated electrons from Cu2O were captured by Ti4+ ions in TiO2 and Ti4+ ions were further reduced to Ti3+ ions. Thus, the photogenerated electrons were stored in Ti3+ ions as the form of energy. These electrons trapped in Ti3+ can be released if a suitable electron acceptor is present. So, the electrons can be transferred to the interface between the composite and solution to participate in photocatalytic reaction. XPS spectra of TiO2/Cu2O composite before and after visible light irradiation were carried out and provided evidence for the presence of Ti3+. The image of high-resolution transmission electron microscopy demonstrates that TiO2 combines with Cu2O tightly. So, the photogenerated electrons can be transferred from Cu2O to TiO2.

Xiong, Liangbin; Yang, Fan; Yan, Lili; Yan, Nannan; Yang, Xi; Qiu, Mingqiang; Yu, Ying

2011-09-01

49

[Decontamination of chemical warfare agents by photocatalysis].  

PubMed

Photocatalysis has been widely applied to solar-energy conversion and environmental purification. Photocatalyst, typically titanium dioxide (TiO(2)), produces active oxygen species under irradiation of ultraviolet light, and can decompose not only conventional pollutants but also different types of hazardous substances at mild conditions. We have recently started the study of photocatalytic decontamination of chemical warfare agents (CWAs) under collaboration with the National Research Institute of Police Science. This article reviews environmental applications of semiconductor photocatalysis, decontamination methods for CWAs, and previous photocatalytic studies applied to CWA degradation, together with some of our results obtained with CWAs and their simulant compounds. The data indicate that photocatalysis, which may not always give a striking power, certainly helps detoxification of such hazardous compounds. Unfortunately, there are not enough data obtained with real CWAs due to the difficulty in handling. We will add more scientific data using CWAs in the near future to develop useful decontamination systems that can reduce the damage caused by possible terrorism. PMID:19122438

Hirakawa, Tsutomu; Mera, Nobuaki; Sano, Taizo; Negishi, Nobuaki; Takeuchi, Koji

2009-01-01

50

Developments in solar photocatalysis for water purification  

Microsoft Academic Search

Photocatalytic processes in the presence of titanium dioxide provide an interesting route to destroy hazardous organic contaminants, being operational in the UV-A domain with a potential use of solar radiation. In this paper, some specific contaminant classes of interest such as ethylbenzene, ?-lindane and EPTC have been tested at laboratory scale and in the field to determine the feasibility of

Alfonso Vidal

1998-01-01

51

Robust cuprous phenanthroline sensitizer for solar hydrogen photocatalysis.  

PubMed

The Cu(I) metal-to-ligand charge-transfer complex, [Cu(dsbtmp)2](+) (dsbtmp = 2,9-di(sec-butyl)-3,4,7,8-tetramethyl-1,10-phenanthroline), exhibits outstanding stability as a visible-light-absorbing photosensitizer in hydrogen-evolving homogeneous photocatalysis. In concert with the Co(dmgH)2(py)Cl water reduction catalyst and N,N-dimethyl-p-toluidine sacrificial donor in 1:1 H2O:CH3CN, this Cu(I) sensitizer remains active even after 5 days of visible-light-pumped (?ex = 452 ± 10 nm) hydrogen evolution catalysis. Deuteration studies illustrate that the hydrogen produced from this composition does indeed originate from aqueous protons. PMID:24028290

Khnayzer, Rony S; McCusker, Catherine E; Olaiya, Babatunde S; Castellano, Felix N

2013-09-17

52

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

53

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

54

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 enabled a more detailed understanding of the mechanisms that govern the electrocatalysis. More specifically, we examine in detail the electrooxidation of C-1 and C-2 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 influence 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. (C) 2012 Elsevier B.V. All rights reserved.

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

2013-01-01

55

Electrocatalysis of anodic and cathodic oxygen-transfer reactions  

Microsoft Academic Search

The electrocatalysis of oxygen-transfer reactions is discussed in two parts. In Part I, the reduction of iodate (IOâ⁻) 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 IOâ⁻ to coincide with the reduction of PtO. The total cathodic charge exceeds the amount required for reduction

Wels

1990-01-01

56

First-Principles Simulation of the Active Sites and Reaction Environment in Electrocatalysis  

SciTech Connect

Electrocatalysis is controlled by the interplay between the active catalytic sites and the influence of their complex environment at the electrified aqueous/metal interface. The most active electrocatalytic materials exquisitely integrate the atomic assembly of the active metal sites responsible for the elementary bond making and breaking steps, together with the carbon support to carry out efficient electron transer, and polymer electrolyte and water to facilitate proton transfer, thus establishing an optimal three-phase interface. Understanding the elementary catalytic processes along with the atomic scale features that control them, however, is obscured by the complexity of this three-phase interface and the dynamic changes that occur to it under operating conditions.

Janik, Michael J.; Wasileski, Sally A.; Taylor, Christopher D.; Neurock, Matthew

2008-04-20

57

Novel swirl-flow reactor for kinetic studies of semiconductor photocatalysis  

SciTech Connect

Heterogeneous photocatalysis has received considerable attention in years as an alternative for treating water polluted with hazardous organic chemicals. A new two-phase swirl-flow monolithic-type reactor was designed to study the kinetics of heterogeneous photocatalytic processes on immobilized semiconductor catalysts. True kinetic rate constants for destruction of a textile dye were measured as a function of wavelength of light intensity and angle of incidence, catalyst layer thickness, and the effect of absorption of light by liquid film on the overall rate of photocatalytic degradation. Photocatalytic activities of two commercially available TiO{sub 2} catalysts (Degussa P25 and Hombikat UV 100) were also compared for different light intensities and catalyst layer thickness. Residence time distribution and mass-transfer limitations were evaluated. This new reactor appears to be an attractive choice for kinetic studies of heterogeneous photocatalysis.

Ray, A.K.; Beenackers, A.A.C.M. [Univ. of Groningen (Netherlands). Dept. of Chemical Engineering

1997-10-01

58

Combinative sonolysis and photocatalysis for textile dye degradation  

SciTech Connect

The merits of combining two advanced oxidation processes, viz., sonolysis and photocatalysis, have been evaluated by investigating the degradation of an azo dye, naphthol blue black (NBB), using a high-frequency ultrasonic generator and UV-photolysis. An additive effect on the degradation rate of the parent compound is observed when the sonolysis and photocatalysis experiments were carried out in a simultaneous or sequential manner. Sonolysis is effective for inducing faster degradation of the parent dye, while TiO{sub 2} photocatalysis is effective for promoting mineralization.

Stock, N.L.; Peller, J.; Vinodgopal, K.; Kamat, P.V.

2000-05-01

59

Photocatalysis on TiO{sub 2} surfaces: Principles, mechanisms, and selected results  

SciTech Connect

In 1972, Fujishima and Honda discovered the photocatalytic splitting of water on TiO{sub 2} electrodes. This event marked the beginning of a new era in heterogeneous photocatalysis. Since then, research efforts in understanding the fundamental processes and in enhancing the photocatalytic efficiency of TiO{sub 2} have come from extensive research performed by chemists, physicists, and chemical engineers. Such studies are often related to energy renewal and energy storage. In recent years, applications to environmental cleanup have been one of the most active areas in heterogeneous photocatalysis. This is inspired by the potential application of TiO{sub 2}-based photocatalysts for the total destruction of organic compounds in polluted air and wastewaters. There exists a vast body of literature dealing with the electron transfer and energy transfer processes in photocatalytic reactions. A detailed description of these processes is beyond the scope of this review. Here, the authors tend to focus on interfacial processes and to summarize some of the operating principles of heterogeneous photocatalysis. In section 2, the authors first look at the electronic excitation processes in a molecule and in a semiconductor substrate. The electronic interaction between the adsorbate molecule and the catalyst substrate is discussed in terms of the catalyzed or sensitized photoreactions. In section 3, thermal and photocatalytic studies on TiO{sub 2} are summarized with emphasis on the common characteristics and fundamental principles of the TiO{sub 2}-based photocatalysis systems. In section 4, they address the research effort in the electronic modification of the semiconductor catalysts and its effect on the photocatalytic efficiency. Several representative examples will be presented including the Schottky barrier formation and modification at metal-semiconductor interfaces. Some concluding remarks and future research directions will be given in the final section. 160 refs.

Linsebigler, A.L.; Lu, G.; Yates, J.T. Jr. [Univ. of Pittsburgh, PA (United States)

1995-05-01

60

An overview of photocatalysis phenomena applied to NOx abatement.  

PubMed

This review provides a short introduction to photocatalysis technology in terms of the present environmental remediation paradigm and, in particular, NOx photoabatement. The fundamentals of photoelectrochemical devices and the photocatalysis phenomena are reviewed, highlighting the main reaction mechanisms. The critical historical developments on heterogeneous photocatalysis are briefly discussed, giving particular emphasis to the pioneer works in this field. The third part of this work focus mainly on NOx removal technology considering topics such as: TiO2 photochemistry; effect of the operating conditions on the photocatalysis process; Langmuir-Hinshelwood modeling; TiO2 photocatalytic immobilization approaches; and their applications. The last section of the paper presents the main conclusions and perspectives on the opportunities related to this technology. PMID:24018117

Angelo, Joana; Andrade, Luísa; Madeira, Luís M; Mendes, Adélio

2013-09-07

61

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

62

Synergetic effects of anodic–cathodic electrocatalysis for phenol degradation in the presence of iron(II)  

Microsoft Academic Search

A novel electrocatalysis method for phenol degradation was described using a ?-PbO2 anode modified with fluorine resin and a Ni–Cr–Ti alloy cathode. In case of air sparging at the cathodic zone, the techniques of anodic–cathodic electrocatalysis (ACEC) and ferrous ion catalyzed anodic–cathodic electrocatalysis (FACEC) in the presence of iron(II) were developed. Both of ACEC and FACEC were more effective than

Zucheng Wu; Minghua Zhou; Dahui Wang

2002-01-01

63

Effect of inorganic ions in heterogeneous photocatalysis of TCE  

SciTech Connect

The influence of 12 ionic compounds (Na{sub 2}SO{sub 4}, NaHCO{sub 3}, Na{sub 2}HPO{sub 4}, NaNO{sub 3}, NaCl, MnCl{sub 2}, NiCl{sub 2}, CaCl{sub 2}, MgCl{sub 2}, AlCl{sub 3}, FeCl{sub 3}, and MgSO{sub 4}) on performance of a fixed-bed photocatalytic reactor is examined. The fixed-bed photocatalyst was developed at Michigan Technological University and comprises 1% Pt-TiO{sub 2} on a silica-based support. The degradation of trichloroethylene (TCE) in Milli-Q water is used to monitor catalyst performance. All compounds are found to inhibit photocatalysis at some or all of the concentrations tested, although only MnCl{sub 2} seems to suppress it altogether. Fouling appears to be a least partially reversible. Electron microprobe analysis is employed to investigate how selected fouling agents interact with the catalyst and support.

Burns, R.A.; Crittenden, J.C.; Hand, D.W.; Selzer, V.H.; Sutter, L.L. [Michigan Technological Univ., Houghton, MI (United States). Dept. of Civil and Environmental Engineering; Salman, S.R. [Yarmouk Univ., Irbid (Jordan). Dept. of Chemistry

1999-01-01

64

Enhanced photocatalysis in a pilot laminar falling film slurry reactor  

SciTech Connect

Laminar falling film slurry (LFFS) photocatalytic reactors are one of the most efficient reactor configurations for conducting heterogeneous photocatalytic reactions, particularly for wastewater treatment. This paper presents a study on the oxidation of an aqueous salicylic acid waste in a pilot continuous flow LFFS photocatalytic reactor which has an optimum design for light absorption. In conducting the oxidation reaction, heterogeneous photocatalysis was supplemented with other photon-assisted processes. The effect of light intensity, radiation wavelength, oxidizing-enhancing agents, substrate and photocatalyst concentration, and exposure time were studied. A comparison of six different photon-based processes showed that higher oxidation rates of salicylic acid were obtained when there was concomitant photocatalysis, photolysis, and UV peroxidation. The oxidation rates of salicylic acid with this combined process were at least 1 order of magnitude higher in comparison with those for UVA photocatalysis and 3-fold higher in comparison with homogeneous UVC photolysis/UVC peroxidation.

Puma, G.L.; Yue, P.L. [Hong Kong Univ. of Science and Technology, Clear Water Bay, Kowloon (Hong Kong)

1999-09-01

65

Model approach to evaluate particle size effects in electrocatalysis: preparation and properties of Pt nanoparticles supported on GC and HOPG  

Microsoft Academic Search

Although metal nanoparticles are widely used in electrocatalysis, in particular for the preparation of the electrodes for fuel cells, it is still not fully understood how the size of a metal phase affects its electrochemical reactivity. In this paper, we demonstrate a possible approach to design model electrodes for studying size effects in electrocatalysis. A simple chemical deposition procedure is

O. V Cherstiouk; P. A Simonov; E. R Savinova

2003-01-01

66

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

67

On the efficacy of electrocatalysis in nonaqueous Li-O2 batteries.  

PubMed

Heterogeneous electrocatalysis has become a focal point in rechargeable Li-air battery research to reduce overpotentials in both the oxygen reduction (discharge) and especially oxygen evolution (charge) reactions. In this study, we show that past reports of traditional cathode electrocatalysis in nonaqueous Li-O(2) batteries were indeed true, but that gas evolution related to electrolyte solvent decomposition was the dominant process being catalyzed. In dimethoxyethane, where Li(2)O(2) formation is the dominant product of the electrochemistry, no catalytic activity (compared to pure carbon) is observed using the same (Au, Pt, MnO(2)) nanoparticles. Nevertheless, the onset potential of oxygen evolution is only slightly higher than the open circuit potential of the cell, indicating conventional oxygen evolution electrocatalysis may be unnecessary. PMID:21995529

McCloskey, Bryan D; Scheffler, Rouven; Speidel, Angela; Bethune, Donald S; Shelby, Robert M; Luntz, A C

2011-10-21

68

Molecular hydrogen formation from photocatalysis of methanol on TiO2(110).  

PubMed

It is well established that adding methanol to water could significantly enhance H2 production by TiO2. Recently, we have found that methanol can be photocatalytically dissociated on TiO2(110) at 400 nm via a stepwise mechanism. However, how molecular hydrogen can be formed from the photocatalyzed methanol/TiO2(110) surface is still not clear. In this work, we have investigated deuterium formation from photocatalysis of the fully deuterated methanol (CD3OD) on TiO2(110) at 400 nm using a temperature programmed desorption (TPD) technique. Photocatalytic dissociation products formaldehyde (CD2O) and D-atoms on BBO sites (via D2O TPD product) have been detected. In addition to D2O formation by heating the photocatalyzed methanol/TiO2(110) surface, we have also observed D2 product formation. D2 is clearly formed via thermal recombination of the D-atoms on the BBO sites from photocatalysis of methanol. Experimental results indicate that D2O formation is more important than D2 formation and that D2 formation is clearly affected by the D2O formation process. PMID:23819680

Xu, Chenbiao; Yang, Wenshao; Guo, Qing; Dai, Dongxu; Chen, Maodu; Yang, Xueming

2013-07-05

69

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

70

Visible light driven type II heterostructures and their enhanced photocatalysis properties: a review  

NASA Astrophysics Data System (ADS)

Considerable efforts have been devoted to enhancing the photocatalytic activity and solar energy utilization of photocatalysts. The fabrication of type II heterostructures plays an important role in photocatalysts modification and has been extensively studied. In this review, we briefly trace the application of type II heterostructured semiconductors in the area of environmental remediation and water splitting, summarize major fabrication methods, describe some of the progress and resulting achievements, and discuss the future prospects. The scope of this review covers a variety of type II heterostructures, focusing particularly on TiO2 and ZnO based visible light driven type II 0D and 1D heterostructured photocatalysts. Some other low dimensional nanomaterials which have shown high-performance photocatalysis are also presented. We expect this review to provide a guideline for readers to gain a clear picture of fabrication and application of type II heterostructures.

Wang, Yajun; Wang, Qisheng; Zhan, Xueying; Wang, Fengmei; Safdar, Muhammad; He, Jun

2013-08-01

71

A comparison of the effectiveness of TiO 2 photocatalysis and UVA photolysis for the destruction of three pathogenic micro-organisms  

Microsoft Academic Search

TiO2 photocatalysis has demonstrated efficacy as a treatment process for water contaminated with chemical pollutants. When exposed to UVA light TiO2 also demonstrates an effective bactericidal activity. The mechanism of this process has been reported to involve attack by valence band generated hydroxyl radicals. In this study when three common bacterial pathogens, Escherichia coli, Salmonella enterica serovar Enteritidis and Pseudomonas

Jeanette M. C. Robertson; Peter K. J. Robertson; Linda A. Lawton

2005-01-01

72

Integration of photocatalysis and biological treatment for azo dye removal – application to AR183  

Microsoft Academic Search

The feasibility of coupling photocatalysis with biological treatment to treat effluents containing azo dyes was examined in this work. With this aim, the degradation of Acid Red 183 was investigated. The very low biodegradability of AR183 was confirmed beforehand by measuring the biological oxygen demand (BOD5). Photocatalysis experiments were carried out in a closed?loop step photoreactor. The reactor walls were

Derradji Chebli; Florence Fourcade; Stephan Brosillon; Saci Nacef; Abdeltif Amrane

2011-01-01

73

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

2013-03-26

74

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

75

Direct bio-electrocatalysis of O2 reduction by Streptomyces coelicolor laccase orientated at promoter-modified graphite electrodes.  

PubMed

Bacterial laccase from Streptomyces coelicolor (SLAC) has been immobilised and orientated at promoter (pyrene and neocuproine)-modified electrodes productively both for direct electron transfer (ET) between the electrode and the T1 Cu site of SLAC and direct (unmediated) bio-electrocatalysis of dioxygen reduction. Its T1 Cu potential ranges between 471 and 318 mV versus the normal hydrogen electrode, at pH 5.5 and 8, respectively; this value is dependent both on the solution pH and electrode modification. In the presence of O2, Cu of the T2/T3 trinuclear centre is distinguished electrochemically at 748-623 mV. Depending on the promoter nature, different orientations of SLAC at pyrene- and neocuproine-modified electrodes can be followed from the kinetic analysis of the ET rates. Bio-electrocatalytic reduction of oxygen starts from the T1 Cu potentials of SLAC, and is most efficient at the promoter-modified electrodes, thereby demonstrating good performance both in neutral and basic media and in solutions with a high NaCl content, such as sea water. The obtained results allow consideration of a broader bioenergetic application of laccases as biocathodes operating directly in such environmental media as sea water and physiological fluids. PMID:23589501

Lörcher, Samuel; Lopes, Paula; Kartashov, Andrey; Ferapontova, Elena E

2013-04-15

76

Effects of TiO2 coating dosage and operational parameters on a TiO2/Ag photocatalysis system for decolorizing Procion red MX-5B.  

PubMed

In this study, titanium dioxide (TiO(2)) powder was coated onto the surface of a dendritic silver (Ag) carrier to synthesize TiO(2)/Ag for decolorizing Procion red MX-5B (MX-5B), and related operation factors were also studied. The results showed that even without ultraviolet-A (UVA) irradiation, the Ag carrier from the TiO(2)/Ag catalyst had oxidizing ability, which could effectively degrade MX-5B color, but TiO(2) was ineffective. In addition, TiO(2) from TiO(2)/Ag demonstrated photocatalysis performance when irradiated, and the Ag carrier further showed an electron-scavenging ability to mitigate electron-hole pair recombination, which can improve the photocatalytic efficacy. With the oxidization and electron-scavenging ability of Ag and the photocatalysis ability of TiO(2), TiO(2)/Ag can decolor MX-5B more efficiently than TiO(2). The heavier Ag carrier also improves the solid-liquid separation of nano-TiO(2), making TiO(2)/Ag more suitable for application in slurry systems of photocatalytic water treatment. When the TiO(2)/Ag coating ratio was 50% by weight, there was a sufficient amount of TiO(2) on Ag's surface with a good distribution, and it exhibited a good photocatalysis decolorizing effect. In a study of how operational factors impact the decolorizing of MX-5B in the TiO(2)/Ag photocatalysis system with UVA irradiation (UVA-TiO(2)/Ag), the decolorization efficiency was optimal when the solution was maintained at pH 6.35. The addition of 0.01 M hydrogen peroxide (H(2)O(2)) aided the photocatalysis decolorization efficiency, although excessive H(2)O(2) reacted with hydroxyl free radicals and decreased the active groups in the system, thereby reducing the photocatalysis activity. An operating temperature of 40 degrees C was conducive to MX-5B decolorization, which was better than operating at room temperature. PMID:20359818

Lin, Yu-Chih; Lee, Ho-Shan

2010-03-15

77

A Surface Science Perspective on TiO2 Photocatalysis  

SciTech Connect

The field of surface science provides a unique approach to understanding bulk, surface and interfacial phenomena occurring during TiO2 photochemistry and photocatalysis. This review highlights, from a surface science perspective, recent literature providing molecular-level insights into phonon-initiated events on TiO2 surfaces obtained in seven key scientific issues: (1) photon absorption, (2) charge transport and trapping, (3) electron transfer dynamics, (4) the adsorbed state, (5) mechanisms, (6) poisons and promoters, and (7) phase and form.

Henderson, Michael A.

2011-06-15

78

Destruction of phenol in water with sun, sand, and photocatalysis  

SciTech Connect

The photocatalytic degradation and oxidation to carbon dioxide of aqueous phenol solutions were studied using natural sunlight in geometries simulating shallow ponds. The photocatalyst was titanium dioxide freely suspended in the solution or immobilized on sand or silica gel. Photodegradation rates were approximately three times faster with the free suspension than with the immobilized catalyst under the same conditions, and were dependent on the time of the year and the time of the day. The seasonal variation correlated roughly with seasonal solar irradiance tabulations for the UV component of the spectrum. For 10 ppm of phenol the maximum rate of solar degradation resulted in a decrease in concentration to 10 ppb in less than 80 min with total mineralization in 110 min. Maintaining the same geometry, 30 L of solution covering 1 m[sup 2] would degrade to the same extent.

Matthews, R.W.; McEvoy, S.R. (CSIRO Division of Coal and Energy Technology, Menai (Australia))

1992-12-01

79

Photocatalysis in water environments using artificial and solar light  

Microsoft Academic Search

This paper presents a review of part of the work done on photocatalytic reactors. Being aware of the comprehensive reports already existing on the chemistry of these reactions [A.M. Braun, L. Jakob, E. Oliveros, C.A. Oller do Nascimento, Adv. Photochem. 18 (1993) 235; O. Legrini, E. Oliveros, A.M. Braun, Chem. Rev. 93 (1993) 671; D. Bahnemann, J. Cunningham, M.A. Fox,

O. M Alfano; D Bahnemann; A. E Cassano; R Dillert; R Goslich

2000-01-01

80

Cationic-anionic mediated charge compensation on La2Ti2O7 for visible light photocatalysis.  

PubMed

The cationic-anionic mediated charge compensation effect was studied in the layered perovskite La2Ti2O7 for the visible light photocatalysis. Our screened hybrid density functional study shows that the electronic structure of La2Ti2O7 can be tuned by the cationic (V, Nb, Ta)/anionic (N) mono- and co-doping. Such mono-doping creates impurity states in the band gap which helps the electron-hole recombination. But if the charge compensation is made by the cationic-anionic mediated co-doping then such impurity states can be removed and can be a promising strategy for visible light photocatalysis. The absolute band edge position of the doped La2Ti2O7 has been aligned with respect to the water oxidation/reduction potential. The calculated defect formation energy shows the stability of the co-doping system is improved due to the coulomb interactions and charge compensations effect. PMID:24013462

Liu, Peng; Nisar, Jawad; Pathak, Biswarup; Ahuja, Rajeev

2013-09-25

81

Developing an efficient TiO2-coated biofilm carrier for intimate coupling of photocatalysis and biodegradation.  

PubMed

Intimate coupling of photocatalysis and biodegradation (ICPB) shows promise to remove recalcitrant organic compounds from water, because photocatalysis breaks the compounds into biodegradable intermediates that are immediately mineralized by microorganisms inside a macroporous carrier, where they are protected from UV light and free radicals. Key to successful ICPB is a carrier capable of accumulating biofilm in its interior and strongly adhering photocatalyst on its exterior. We employed a low-temperature sintering method, the O method, to adhere TiO(2) to sponge-type macroporous carriers. The O method achieved a 7-fold increase of TiO(2) density, compared to the previously used sol-gel method, and it conserved the macropores for biofilm accumulation. Although the O-method carrier met the basic requirements of ICPB when degrading 2,4,5 trichlorophenol, it had low photocatalytic activity for breaking down more complex aromatics, like reactive dyes. Therefore, we improved the sintering method in two steps called the D and DN methods: reducing the TiO(2) concentration and then removing trimesic acid in the coating solution. The photocatalytic efficiency towards reactive black 5 increased 5 fold for the D method and 10 fold for DN method, and the DN carrier had superior TiO(2) adherence during long-term operation. PMID:23062834

Li, Guozheng; Park, Seongjun; Rittmann, Bruce E

2012-09-25

82

Photocatalysis over titania on iron oxide  

NASA Astrophysics Data System (ADS)

Photocatalytic activity of TiO{2} deposited on spherical sub micron-sized Fe{2}O{3} particle was investigated under ultraviolet or visible light. The Fe{2}O{3} particles were prepared using a spray pyrolysis of aqueous Fe(NO{3})3 solution in air flow. TiO{2} was deposited on Fe{2}O{3} particle by irradiation of ultraviolet or visible light to the suspension of Fe{2}O{3} particle and a TiO{2} precursor. When TiO{2} was formed under visible light (TiO{2}/Fe{2}O{3}-VIS), there were reasonable trends in the phase shift of PAS signal and EDX signal of Ti. However, there was no trend for the case of ultra violet irradiation (TiO{2}/Fe{2}O{3}-UV). TiO{2}/Fe{2}O{3}-VIS showed higher rates of decomposition of organic compound, of decrease in contact angle of water drop, and of decrease in the number of E. coli under visible light than TiO{2}/Fe{2}O{3}-UV or TiO{2} film. From the results, it was suggested that TiO{2}/Fe{2}O{3}-VIS had a regular thin layer of TiO{2} compared to TiO{2}/Fe{2}O{3}-UV and the photo-generated carrier(s) in iron oxide migrated to the surface of TiO{2} in the case of TiO{2}/Fe{2}O{3}-VIS.

Kim, Kwi Cheol; Han, Chong Soo

2006-03-01

83

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

84

Controlling the levels of airborne pollen: can heterogeneous photocatalysis help?  

PubMed

Airborne pollen is a worldwide problem because is a very important allergenic agent; it can be altered only by certain microorganisms and by some oxidizers, such as reactive oxygen species (ROS). On the other hand, heterogeneous photocatalysis (HPC) arose as a promising technology for reducing the level of contaminants in the air, based on their degradation by the production of ROS. In this paper, study of the feasibility of HPC to diminish the counts of pollen is undertaken. The research has been carried out at different levels, from solutions to mortar specimens with the evidence that HPC is able to reduce the amount of pollen grains. This is a major breakthrough that opens the door to a whole field of research, already full of gaps, whose implications could be quite controversial. PMID:24063577

Sapiña, M; Jimenez-Relinque, E; Castellote, M

2013-09-24

85

Visible Light Photocatalysis: The Development of Photocatalytic Radical Ion Cycloadditions.  

PubMed

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

2013-05-01

86

Visible light photocatalysis as a greener approach to photochemical synthesis  

NASA Astrophysics Data System (ADS)

Light can be considered an ideal reagent for environmentally friendly, 'green' chemical synthesis; unlike many conventional reagents, light is non-toxic, generates no waste, and can be obtained from renewable sources. Nevertheless, the need for high-energy ultraviolet radiation in most organic photochemical processes has limited both the practicality and environmental benefits of photochemical synthesis on industrially relevant scales. This Perspective describes recent approaches to the use of metal polypyridyl photocatalysts in synthetic organic transformations. Given the remarkable photophysical properties of these complexes, these new transformations, which use Ru(bpy)32+ and related photocatalysts, can be conducted using almost any source of visible light, including both store-bought fluorescent light bulbs and ambient sunlight. Transition metal photocatalysis thus represents a promising strategy towards the development of practical, scalable industrial processes with great environmental benefits.

Yoon, Tehshik P.; Ischay, Michael A.; Du, Juana

2010-07-01

87

Epilayer control of photodeposited materials during UV photocatalysis  

SciTech Connect

Epilayer control of photoassisted oxidation and reduction on the ferroelectric PbTiO{sub 3} polar surface was investigated. Photo-oxidation of a AgNO{sub 3} electrolyte resulting in formation of Ag{sub 7}NO{sub 11} particles was observed on the PbTiO{sub 3}/Nb:SrTiO{sub 3} film surface; whereas PbTiO{sub 3}/SrRuO{sub 3}/SrTiO{sub 3} leads to AgNO{sub 3} reduction under UV illumination. The oxidation reaction resulting in the formation of Ag{sub 7}NO{sub 11} is explained in terms of a rectifying interface between PbTiO{sub 3} and Nb:SrTiO{sub 3}, controlling the charge transport during UV photocatalysis.

Takahashi, R.; Dahl, O.; Grepstad, J. K.; Tybell, T. [Department of Electronics and Telecommunications, Norwegian University of Science and Technology, OS Bragstads plass 2A, Trondheim 7491 (Norway); Katayama, M.; Matsumoto, Y. [Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midoriku, Yokohama 226-8503 (Japan)

2009-06-08

88

Band-engineered CaTiO3 nanowires for visible light photocatalysis  

NASA Astrophysics Data System (ADS)

We have theoretically investigated the structural, electronic, and optical properties of the perovskite CaTiO3 nanowires for visible light photocatalytic applications using pseudopotential density-functional theory calculations. The electronic structure calculations show that the band gap is greatly modified in the CaTiO3 nanowires compared with that of the bulk. For the TiO2-terminated nanowires, the electronic states on the valence band maxima induced by combining oxygen and calcium 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 combining oxygen and calcium atoms on the surface of the CaO-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 shifts towards the red-light region. These theoretical results suggest that the perovskite CaTiO3 nanowires are promising candidates for visible light photocatalysis such as solar-assisted water splitting reactions.

Fu, Q.; Li, J. L.; He, T.; Yang, G. W.

2013-03-01

89

Generation of Organic Radicals During Photocatalysis on TiO2  

NASA Astrophysics Data System (ADS)

It is well-known that water-related radicals (such as OH. species) are produced by charge transfer events at UV-irradiated TiO2 surfaces. In contrast, organic radicals are generally viewed as being formed by reactions with OH. groups and not by direct charge transfer events. Using rutile TiO2(110) as a model photocatalyst, we show that organic radicals are generated in single-step charge transfer events during photodecomposition of adsorbed carboxylates and ketones. Some organic radicals (e.g., methyl) are ejected from the surface and, in high surface area catalysts, experience reactions away from the surface of origin. Other radicals (e.g., ethyl and t-butyl) have limited ability to escape the surface of origin without capture and subsequent thermal reactions. Understanding the chemistry associated with organic radical formation on TiO2 opens the door for more detailed examinations of charge transfer dynamics and energy redistribution during photon-initiated reactions important to heterogeneous photocatalysis.

Henderson, Michael

2008-03-01

90

Fuel cell applied research: electrocatalysis and materials. Quarterly report, July 1-September 30, 1979  

SciTech Connect

The effect of underpotential deposited metal layers on the electrocatalysis of fuel cell reactions was studied. It was found that Bi, Ag and Pb form underpotential deposited metal adatom layers on gold in 85% H/sub 3/PO/sub 4/. Underpotential deposited Bi enhances oxygen reduction on gold with the formation of peroxide. Underpotential deposited Ag on the other hand inhibits oxygen reduction. Results indicate the potential for developing organic compound/air fuel cells using underpotential deposited Pb adatoms to enhance the electrocatalysis of the fuel electrode. The effects of adsorbed layers of Pb, Tl and Bi on formic acid and methanol oxidation on platinum in 85% H/sub 3/PO/sub 4/ were investigated. The effect of crystal orientation on formic acid oxidation on platinum in 1 M CHlO/sub 2/ was investigated. The kinetics of the oxygen reduction and evolution reactions at the electrode (metal or oxide)-solid electrolyte (yttria stabilized zirconia) interface were investigated using ac and dc techniques. Platinum point contact electrodes were also used in the preliminary studies of the fuel electrode reaction. dc, ac and potential sweep methods were used in this study. Results are reported. Progress on a survey of status studies of phosphoric acid and molten carbonate fuel cells is reported. (WHK)

Srinivasan, S.; Isaacs, H.S.; McBreen, J.; O'Grady, W.E.; Olender, H.; Olmer, L.J.; Schouler, E.J.L.; Adzic, R.R.

1980-03-01

91

Kinetic analysis and energy efficiency of phenol degradation in a plasma-photocatalysis system.  

PubMed

Combination of two kinds of advanced oxidation processes (AOPs) is an effective approach to control wastewater pollution. In this research, a pulsed discharge plasma system with multi-point-to-plate electrode and an immobilized TiO(2) photocatalysis system is coupled to oxidize target pollutant in aqueous solution. Kinetic analysis (pseudo-first order kinetic constant, k) and energy efficiency (energy yield value at 50% phenol conversion, G(50)) of phenol oxidation in different reaction systems (plasma alone and plasma-photocatalysis) are reviewed to account for the synergistic mechanism of plasma and photocatalysis. The experimental results show that higher k and G(50) of phenol oxidation can be obtained in the plasma-photocatalysis system under the conditions of different gas bubbling varieties, initial solution pH and radical scavenger addition. Moreover, the investigation tested hydroxyl radical (OH) is the most important species for phenol removal in the synergistic system of plasma-photocatalysis as well as in the plasma alone system. PMID:21232856

Wang, Hui-juan; Chen, Xiao-yang

2010-12-27

92

CO2 SEQUESTRATION AND RECYCLE BY PHOTOCATALYSIS WITH VISIBLE LIGHT  

SciTech Connect

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 research tasks accomplished during first six months include setting up a photo-catalytic reactor, optical bench, calibration of gas chromatograph, catalyst preparation, and catalyst screening study. Addition of Pt and Cu on TiO{sub 2} was found to increase the activity of TiO{sub 2} catalysts for the synthesis of methanol and methane. The most active catalysts obtained from this study will be used for mechanistic study. 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

1999-12-31

93

Treatment of formaldehyde by corona plasma cooperated with photo-catalysis  

NASA Astrophysics Data System (ADS)

Formaldehyde, as a main indoor pollutant, is a serious hazard for human health. Here the experimental results of dielectric discharge, together with photo-catalysis to treat formaldehyde, were presented. The modified photocatalyst was loaded onto the electrode surface for degradation of formaldehyde in an artificially enclosed room. The effect of catalyst quantity, inlet rate, temperature, humidity and other process variables were examined in order to explore the relative purification factors of plasma cooperated with photo-catalysis. It is found that formaldehyde degradation efficiency is proportional to photo-catalyst quantity, and reciprocal to gas inlet rate and humidity. Experimental results confirm that plasma discharge combined with photo-catalysis can significantly improve the treatment efficiency of formaldehyde compared to a single plasma discharge. This research may form a basis for practical development of an efficient, low-power-cost, and relatively comprehensive indoor pollutant purification system.

Yue, X. G.; He, Z. H.; Ma, P. Y.; Zhu, L.; Ma, J.; Zhao, H.

2013-03-01

94

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.

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

2012-01-01

95

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

96

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

2013-02-04

97

Gas phase trichloroethylene (TCE) photooxidation and byproduct formation: photolysis vs. titania\\/silica based photocatalysis  

Microsoft Academic Search

Photooxidation of trichloroethylene (TCE) was examined in comparative study using photolysis and photocatalysis. Degussa P25 titania coated on reactor wall and deposited on silica based microporous support were used as photocatalyst. The destruction of TCE and formation of potential byproducts were investigated under steady state conditions using annular photoreactors. Experimental work involved passing polluted air containing TCE through the UV

Madjid Mohseni

2005-01-01

98

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.

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

2012-01-01

99

Heterogeneous photocatalysis of real textile wastewater: Evaluation of reaction kinetics and characterization  

Microsoft Academic Search

Real textile wastewater collected from the cotton dyeing bath of a fabric dyeing and finishing plant was subjected to heterogeneous photocatalysis using Ag doped TiO2 under UV irradiation in a batch reactor. The photocatalysts were characterized by FESEM, XRD, EDS, FTIR, DRS and BET analyses. The kinetics of the reaction was also evaluated. Colour removal was more than 88%, 94%

Chittaranjan Sahoo; Ashok K. Gupta; Indu M. Sasidharan Pillai

2012-01-01

100

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

101

Photocatalytic oxidation of grey water over titanium dioxide suspensions  

Microsoft Academic Search

Grey water reuse is an attractive alternative to the sustainable management of water especially under water scarcity situations. In this work, photocatalysis over titanium dioxide particles has been applied as a novel alternative to already studied treatments of grey waters such as filtration, biological processes, disinfection and\\/or coagulation technologies. Grey waters coming from two different sources, a hotel and a

M. Sanchez; M. J. Rivero; I. Ortiz

2010-01-01

102

A novel shape-controlled synthesis of dispersed silver nanoparticles by combined bioaffinity adsorption and TiO 2 photocatalysis  

Microsoft Academic Search

Shape-controlled silver nanoparticles (Ag NPs) were prepared in a well-dispersed mode on the active imprinting sites of chitosan-TiO2 adsorbent (CTA) by means of bioaffinity adsorption and TiO2 photocatalysis. Nontoxic hydrogen peroxide (H2O2) was used as a suitable etching reagent in our production of shape-controlled Ag NPs, since it could regulate the TiO2 photocatalysis and accelerate the generation of O2. With

Enzan Chen; Haijia Su; Wanying Zhang; Tianwei Tan

2011-01-01

103

Hydrogenation and Ammoniation of SrTiO3 for an Enhanced Visible-light Photocatalysis  

NASA Astrophysics Data System (ADS)

Hydrogenation and ammoniation of SrTiO3 (STO), a normal ultraviolet photocatalyst, were performed by annealing STO<100> in H2:N2=5%:95% and NH3, respectively, at various temperatures T. It was found that hydrogenation at T>=900 °C remarkably enhanced the UV photocatalytic ability of STO, but the visible-light photocatalysis was still unavailable, while ammoniation at T>=800 °C introduced the N doping, resulting in visible-light photocatalytic activity. Furthermore, when a hydrogenated STO was subjected to ammoniation, the visible-light photocatalytic ability was nearly the same as that of the ammoniated one; but the hydrogenation of an ammoniated one significantly enhanced visible-light photocatalysis, indicating a synergetic effect of hydrogenation and ammoniation. Discussions and identifications have been made to analyze these results.

Sun, Tao; Zhao, You-yuan; Lu, Ming

2012-02-01

104

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

105

Low-Coordination Sites in Oxygen-Reduction Electrocatalysis: Their Roles and Methods for Removal  

SciTech Connect

Low-coordination sites, including edges, kinks, and defects, play an important role in oxygen-reduction electrocatalysis. Their role was studied experimentally and theoretically for various Pt surfaces. However, the roughness effect on similar-sized nanoparticles that could elucidate the role of low-coordination sites has attracted much less attention, with no studies on Pd nanoparticles. Here, using Br- adsorption/desorption, we introduce an effective approach to reduce surface roughness, yielding Pd nanoparticles with smoother surfaces and an increased number of (111)-oriented facets. The resulting nanoparticles have a slightly contracted structure and narrow size distribution. Pt monolayer catalysts that contain such nanoparticles as the cores showed a 1.5-fold enhancement in specific and Pt mass activities for the oxygen reduction reaction compared with untreated ones. Furthermore, a dramatic increase in durability was observed with bromide-treated Pd{sub 3}Co cores. These results demonstrate a simple approach to preparing nanoparticles with smooth surfaces and confirm the adverse effect of low-coordination sites on the kinetics of the oxygen-reduction reaction.

Cai, Y.; Ma, C.; Zhu, Y.; Wang, J.X.; Adzic, R.R.

2011-07-05

106

TiO2 Photocatalysis: A Historical Overview and Future Prospects  

Microsoft Academic Search

Photocatalysis has recently become a common word and various products using photocatalytic functions have been commercialized. Among many candidates for photocatalysts, TiO2 is almost the only material suitable for industrial use at present and also probably in the future. This is because TiO2 has the most efficient photoactivity, the highest stability and the lowest cost. More significantly, it has been

Kazuhito Hashimoto; Hiroshi Irie; Akira Fujishima

2005-01-01

107

Molecular design in photocatalysis: Physiocochemical principles for designing high-efficiency photocatalytic oxidation-reduction systems  

SciTech Connect

In the 1970s, searches for alternative energy sources were activated due to the rising threat of the energy crisis. This threat in particular served as a powerful stimulus for full-scale investigations in the field of photocatalysis in many laboratories around the world. The authors generalize the results of this research and develop the concept of molecular design as a strategy for controlling photocatalytic processes by designing organized systems in which all the conversions connected with electron transfer are coordinated.

Krynkov, A.L.; Kuchmii, S.Y.; Pokhodenko, V.D. [L.V. Pisarzhevskii Inst. of Physical Chemistry, Kiev (Ukraine)

1995-01-01

108

Photocatalytic decolourization of reactive azo dye: A comparison between TiO 2 and us photocatalysis  

Microsoft Academic Search

This study examined the photocatalytic degradation of reactive black 5 (RB5), a reactive azo dye, by TiO2 and US. An aerated semiconductor suspension was illuminated in a batch-lab-scale reactor. Both reactions followed first order kinetics. The effects of initial pH, semiconductor dosage, light intensity, initial dye concentration and temperature were investigated. US photocatalysis of RB5 followed the Langmuir-Hinshelwood equation while

Lars Baetz Reutergådh; Mallika Iangphasuk

1997-01-01

109

Efficient visible light photocatalysis in cubic Sr2FeNbO6  

Microsoft Academic Search

Cubic phase Sr2FeNbO6 (SFNO) particles were synthesized and studied experimentally for visible light photocatalysis. The photocatalytic activity for hydrogen (2 times) and oxygen (1.1 times) evolution was very high, as compared to that for PbBi2Nb2O9 (visible light active photocatalysts). As a qualitative guiding tool, a density functional theory study of cubic SFNO demonstrates that the valence band consists of O2p

E. D. Jeong; S. M. Yu; J. Y. Yoon; J. S. Bae; C. R. Cho; K. T. Lim; Rekha Dom; P. H. Borse; H. G. Kim

2012-01-01

110

Adsorption and photocatalysis kinetics of herbicide onto titanium oxide and powdered activated carbon  

Microsoft Academic Search

The adsorption and photocatalysis kinetics of metsulfuron-methyl (MM) onto titanium oxide (TiO2) and powdered activated carbon (PAC) were studied at varying adsorbent amount and MM concentration. The overall mass transfer in adsorption was estimated from concentration decay curves obtained in the batch adsorber. The maximum adsorption capacity decreased with increasing adsorbent amount in TiO2 adsorption. The adsorption isotherms of MM

Seoung-Hyun Kim; Huu Hao Ngo; H. K. Shon; S. Vigneswaran

2008-01-01

111

Structure and photocatalysis activity of silver doped titanium oxide nanotubes array for degradation of pollutants  

NASA Astrophysics Data System (ADS)

Semiconductor titanium oxide showed a wonderful performance as a photocatalysis for environmental remediation. Owing to high stability and promising physicochemical properties, titanium oxide nanostructures are used in various applications such as wastewater treatment, antimicrobial and air purification. In the present study, titanium oxide nanotubes and silver doped titanium oxide nanotubes were synthesized via anodic oxidation method. The morphology and composition structure were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results depicted that nanotubes possess anatase phase with average tube diameter of 65 nm and 230 ± 12 nm in length. The band gap of the un-doped and silver doped titanium dioxide nanotubes was determined using UV-Vis. spectrophotometer. The results showed that the band gap of titanium dioxide nanotubes is decreased when doped with silver ions. The photocatalysis activity of un-doped and silver doped TiO2 nanotubes were evaluated in terms of degradation of phenol in the presence of ultra violet irradiation. It was found that silver doped TiO2 nanotubes exhibited much higher photocatalysis activity than un-doped TiO2 nanotubes.

Al-Arfaj, E. A.

2013-10-01

112

Hole mediated coupling in Sr2Nb2O7 for visible light photocatalysis.  

PubMed

The band gap reduction and effective utilization of visible solar light are possible by introducing the anionic hole-hole mediated coupling in Sr(2)Nb(2)O(7). By using the first principles calculations, we have investigated the mono- and co-anionic doping (S, N and C) in layered perovskite Sr(2)Nb(2)O(7) for the visible-light photocatalysis. Our electronic structure and optical absorption study shows that the mono- (N and S) and co-anionic doped (N-N and C-S) Sr(2)Nb(2)O(7) systems are promising materials for the visible light photocatalysis. The calculated binding energies show that if the hole-hole mediated coupling could be introduced, the co-doped systems would be more stable than their respective mono-doped systems. Optical absorption curves indicate that doping S, (N-N) and (C-S) in Sr(2)Nb(2)O(7) can harvest a longer wavelength of the visible light spectrum as compared to the pure Sr(2)Nb(2)O(7) for efficient photocatalysis. PMID:22389023

Nisar, Jawad; Pathak, Biswarup; Wang, Baochang; Kang, Tae Won; Ahuja, Rajeev

2012-03-05

113

Direct electrochemistry and electrocatalysis of horseradish peroxidase immobilized in sol–gel-derived tin oxide\\/gelatin composite films  

Microsoft Academic Search

Horseradish peroxidase (HRP) was immobilized into a new type of sol–gel-derived nano-sized tin oxide\\/gelatin composite film (SnO2 composite film) using a sol–gel film\\/enzyme\\/sol–gel film “sandwich” configuration. Direct electrochemistry and electrocatalysis of HRP incorporated into the composite films were investigated. HRP\\/SnO2 composite film exhibited a pair of stable and quasi-reversible cyclic voltammetric peaks for the HRP Fe(III)\\/HRP Fe(II) redox couple with

Nengqin Jia; Qin Zhou; Ling Liu; Manming Yan; Zhiyu Jiang

2005-01-01

114

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

115

Development of a new photocatalytic reactor for water purification  

Microsoft Academic Search

The purification of water by heterogeneous photocatalysis is one of the most rapidly growing areas of interest to both research workers and water purification plants. Recent literature has demonstrated on a laboratory scale the potential of this promising technology to completely destroy organic pollutants dissolved or dispersed in water into harmless substances. However, to date no viable pilot plant exists

Ajay K. Ray; Antonie A. C. M. Beenackers

1998-01-01

116

Rotating ring disk electrode theory dealing with nonstationary electrocatalysis: Study of the electrocatalytic reduction of dioxygen at cobalt protoporphyrin modified electrode  

Microsoft Academic Search

An equation describing the variation of rate constant (k) with reaction charge (Q) and potential (E) for electrocatalysis is derived. A rotating ring disk electrode (RRDE) theory dealing with kinetic problems for dioxygen reduction at an unstable electrode is proposed. Using a rotation-scan RRDE method the kinetic behavior for the catalytic reduction of dioxygen at cobalt protoporphyrin modified pyrolytic graphite

Rongzhong. Jiang; Shaojun. Dong

1990-01-01

117

Differences in elimination efficiencies of Escherichia coli in freshwater and seawater as a result of TiO2 photocatalysis.  

PubMed

The effects of UV irradiation on the respiration and survival of Escherichia coli in various concentrations of aqueous NaCl were investigated in the presence of a photocatalyst. In this study, we anticipated that the photocatalysis of residual chlorine generated in a solution containing Cl(-) would result in bacterial elimination. Our results indicated a gradual reduction in the E. coli survival ratio in freshwater; however, no decrease in total abundance was observed during 8 h of photocatalysis with UV irradiation. Conversely, the survival ratio of E. coli in the artificial seawater decreased drastically as a consequence of photocatalysis, with a concomitant decrease in total abundance. These results revealed that the chlorinated active species that formed on the photocatalyst surface influenced the observed inactivation. PMID:23523173

Yamada, Namiha; Suzumura, Masahiro; Koiwa, Fumiko; Negishi, Nobuaki

2013-03-06

118

Photocatalytic degradation of pesticide contaminants in water  

Microsoft Academic Search

Photocatalysis has been proved to be an effective and inexpensive tool for the removal of organic and inorganic pollutants from water. Of particular interest in this context, in recent years, has been the complete photocatalytic mineralisation of a variety of pesticides into harmless products. The technique is now reaching the pre-industrial level, with several pilot plants and prototypes being operational

Suja Devipriya; Suguna Yesodharan

2005-01-01

119

Iron(III)-oxo centers on TiO{sub 2} for visible light photocatalysis.  

SciTech Connect

Isolated iron(III)-oxo clusters were synthesized onto TiO{sub 2} using atomic layer deposition. The Fe{sub x}O{sub y}/TiO{sub 2} nanocomposites have unique properties that enable not only absorption of visible light, but efficient photocatalysis as demonstrated by methylene blue degradation. The localization of photogenerated electrons in core TiO{sub 2} nanocrystallites upon visible light excitation demonstrates coupling of conduction bands of mixed oxides. The redox properties of photogenerated charges in nanocomposites were studied using in situ electron paramagnetic resonance spectroscopy.

Libera, J. A.; Elam, J. W.; Sather, N. F.; Rajh, T.; Dimitrijevic, N. M. (Center for Nanoscale Materials); ( CSE); ( ES)

2009-01-01

120

Photocatalysis of sculptured thin films of TiO{sub 2}  

SciTech Connect

Enhanced surface reaction efficiency has been demonstrated in the photocatalysis of obliquely deposited TiO{sub 2} thin films with variously shaped columns such as zigzag, cylinder, and helix. The columnar thickness and spacing play an important role in the enhancement of the effective surface area, while the columnar shape is less important. The optimum morphology for a surface reaction has been obtained at the deposition angle {alpha}=70{degree}, where the photocatalytic activity is 2.5 times larger than that at {alpha}=0{degree}. The morphology controlled obliquely deposited thin films are applicable for solar cell, electro- and photochromic devices besides photocatalyst. {copyright} 2001 American Institute of Physics.

Suzuki, Motofumi; Ito, Tadayoshi; Taga, Yasunori

2001-06-18

121

Effect of inorganic ions in heterogeneous photocatalysis of TCE  

Microsoft Academic Search

The influence of 12 ionic compounds (NaâSOâ, NaHCOâ, NaâHPOâ, NaNOâ, NaCl, MnClâ, NiClâ, CaClâ, MgClâ, AlClâ, FeClâ, and MgSOâ) on performance of a fixed-bed photocatalytic reactor is examined. The fixed-bed photocatalyst was developed at Michigan Technological University and comprises 1% Pt-TiOâ on a silica-based support. The degradation of trichloroethylene (TCE) in Milli-Q water is used to monitor catalyst performance. All

Robert A. Burns; John C. Crittenden; David W. Hand; Volker H. Selzer; Lawrence L. Sutter; Salman R. Salman

1999-01-01

122

Treatment of phenylmercury salts by heterogeneous photocatalysis over TiO(2).  

PubMed

UV/TiO(2) photocatalysis of phenylmercury salts in aqueous solutions has been performed starting from both acetate (C(6)H(5)HgCH(3)CO(2), PMA) and chloride (C(6)H(5)HgCl, PMC) salts, in the presence or the absence of oxygen at acidic pH. Removal of Hg(II) in solution took place with the simultaneous deposit of dark or pale gray solids on the photocatalyst, identified as metallic Hg (when starting from PMA) or mixtures of Hg(0) and Hg(2)Cl(2) (when starting from PMC). Partial mineralization of the organic part of both compounds has also been achieved. Hg(II) removal and mineralization were enhanced in the absence of oxygen. PMA photocatalysis followed a saturation kinetics, going from first order at low concentration to zero order at higher concentrations (>0.5mM). For PMA, reaction was faster at high pH (11) with formation of mixtures of Hg and HgO. Phenol was detected as a product of the reaction in both cases, PMA and PMC, and no formation of dangerous methyl- or ethylmercury species was observed in the first case. A mechanism for the photocatalytic reaction has been proposed. The fact that calomel was found as a deposit when starting from PMC under nitrogen suggests that the mechanism of Hg(II) transformation proceeds through successive one-electron transfer reactions passing by mercurous forms. PMID:17604821

de la Fournière, Emmanuel M; Leyva, Ana G; Gautier, Eduardo A; Litter, Marta I

2007-07-02

123

Photochemical degradation of triazine herbicides - comparison of homogeneous and heterogeneous photocatalysis.  

PubMed

Photochemical degradation of atrazine under different conditions was studied and compared, namely degradation via photocatalysis on TiO2, UV C photolysis, and homogeneous photocatalysis in the presence of added ferric ions. The reaction rate constants in heterogeneous photocatalytic reactions on TiO2 and of photolytic degradation by means of UV C light are similar, 0.018 min(-1) and 0.020 min(-1), respectively. The reaction rate constants in homogeneous photocatalytic reactions with Fe(III) added depend strongly on the Fe(III) concentration, 0.0017 min(-1) for 1.6 × 10(-6) mol l(-1) Fe(III) to 0.105 min(-1) for 3.3 × 10(-4) mol l(-1) Fe(III). In all types of reactions, dechlorination was observed; in homogeneous photocatalytic reactions and in UV C (250-300 nm) photolysis, dechlorination proceeds with a 1?:?1 stoichiometry to atrazine degradation, in photocatalytic reactions on TiO2, dechlorination measured as chloride ion release reaches only 1/5 of the substrate degradation. In photocatalytic reactions on TiO2, mineralisation of 40% carbon was observed. PMID:23069861

Klementova, Sarka; Zlamal, Martin

2013-04-01

124

Evaluation of the tratment of metal-EDTA complexes using Ti0{sub 2} photocatalysis  

SciTech Connect

This study has demonstrated the feasibility of TiO{sub 2} photocatalysis to treat EDTA and several metal-EDTA complexes that can be found in industrial wastewaters. For the EDTA complexes of metals capable of photodeposition, such as Cu and Pb, certain reaction conditions were shown to facilitate the simultaneous complex degradation and photodeposition of these metals onto the catalyst. With metals that do not easily photodeposit, such as Ni and Cd, it is shown that the complex degradation is still facilitated, and can enhance other metals removal processes after photocatalytic treatment. Because the treatment of these metal-EDTA complexes typically requires special measures, there may exist situations where TiO{sub 2} photocatalysis could actually be the preferred method of treatment. However, its use should be compared economically to other more established advanced oxidation technologies. This necessity is demonstrated in the economic comparison to ozone treatment for EDTA degradation alone, where ozone treatment appears to be the clear choice in this application.

Madden, T.; Datyte, A.K. [New Mexico Univ., Albuquerque, NM (United States). Center for Micro-Engineered Ceramics; Prairie, M.R.; Stange, B.M. [Sandia National Labs., Livermore, CA (United States)

1996-03-01

125

Water incorporation studies on doped barium cerate perovskites  

Microsoft Academic Search

BaCeO3-based perovskites exhibit high proton conductivities and are attractive candidates for application in electrocatalysis and fuel cells. In BaCe1?xYxO3?x\\/2, 0?x?0.15, the degree of hydration is directly related to the oxygen vacancy concentration and increases linearly with dopant content, x. The water content of the material depends predominantly on the number of oxygen vacancies. At maximum hydration, ca. 80% of oxygen

Angela Kruth; John T. S. Irvine

2003-01-01

126

Visible light photocatalysis of single-walled (Zn4/6Cu2/6O)3/(Zn5/6Cu1/6O)3 superlattice nanotube for redox reaction of water calculated by generalized gradient approximations with the Hubbard U model  

NASA Astrophysics Data System (ADS)

To use ZnO for visible light water photoelectrolysis, the bandgap Eg of ZnO should be dropped into the visible light region. This is realized by establishing a novel single-walled (Zn4/6Cu2/6O)3/(Zn5/6Cu1/6O)3 superlattice nanotube of (6,0) type, whose Eg is determined using the density functional theory of generalized gradient approximations with the Hubbard U model (GGA + U). The results show that the Eg value of the superlattice is 2.16 eV. The absorption ability of the incident solar spectrum reaches 42% in comparison with 5% of ZnO. The physical mechanism of this band structure variation is the existence of the concentration gradient of Cu at the interface within the superlattice. The corresponding location of the superlattice of the bandgap also satisfies the redox reaction of water. Thus, the superlattice can be an exciting candidate for water photoelectrolysis materials using visible light.

Song, D. M.; Li, J. C.; Jiang, Q.

2012-02-01

127

Electrocatalysis for chlorine electrode reaction on RuO/sub 2/ electrode in NaAlCl/sub 4/ melt  

SciTech Connect

In molten AlCl/sub 3/-NaCl with near equimolar compositions, electrocatalysis of the chlorine electrode reaction (2Cl/sup -/.Cl/sub 2/+2e/sup -/) on RuO/sub 2/ electrodes has been investigated at 175/degree/C. Melt-stable RuO/sub 2/ electrodes were prepared by a thermal decomposition method on semiconductive SnO/sub 2/ films deposited on Pyrex substrates. Tafel relationships for chlorine evolution and reduction were studied as functions of pCl(.-log a/sub Cl/-) and partial pressure of Cl/sub 2/, and several kinetic parameters including reaction orders with respect to Cl/sup -/ and Cl/sub 2/ were determined. This work is pertinent to electric batteries. 40 refs.

Uchida, I.; Urushibata, H.; Toshima, S.

1981-11-01

128

Filling carbon nanotubes with Ni-Fe alloys via methylbenzene-oriented constant current electrodeposition for hydrazine electrocatalysis  

NASA Astrophysics Data System (ADS)

A simple and novel method to fill carbon nanotubes (CNTs) with Ni-Fe alloys by methylbenzene-oriented constant current electrodeposition is demonstrated. The method is based on the difference in the surface conductivity of CNTs inside and outside in electrodeposition process owing to the covering of methylbenzene. The Ni-Fe alloys filled multiwalled carbon nanotubes (MWCNTs) were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and atomic absorption spectroscopy (AAS), respectively. Then the Ni-Fe alloys filled MWCNTs were used as hydrazine oxidation electrocatalysts in direct hydrazine (N2H4)-air fuel cells. Cyclic voltammograms (CVs) indicated that Ni85Fe15-filled MWCNTs had superior electrocatalytic activity for hydrazine electrocatalysis than catalysts with other compositions.

Wang, Jia; Dong, Zhengping; Huang, Jingwei; Li, Jing; Jin, Xiaodong; Niu, Jianrui; Sun, Jian; Jin, Jun; Ma, Jiantai

2013-04-01

129

PHOTOELECTROCHEMISTRY AND PHOTOCATALYSIS IN NANOSCALE INORGANIC CHEMICAL SYSTEMS  

SciTech Connect

The goal of our DOE-supported research has been to explore the use of solid state materials as organizing media for, and as active components of, artificial photosynthetic systems. In this work we strive to understand how photoinduced electron and energy transfer reactions occur in the solid state, and to elucidate design principles for using nanoscale inorganic materials in photochemical energy conversion schemes. A unifying theme in this project has been to move beyond the study of simple transient charge separation to integrated chemical systems that can effect permanent charge separation in the form of energy-rich chemicals. This project explored the use of zeolites as organizing media for electron donor-acceptor systems and artificial photosynthetic assemblies. Layer-by-layer synthetic methods were developed using lamellar semiconductors, and multi-step, visible light driven energy/electron transfer cascades were studied by transient specroscopic techniques. By combining molecular photosensitizers with lamellar semiconductors and intercalated catalyst particles, the first non-sacrificial systems for visible light driven hydrogen evolution were developed and studied. Oxygen evolving catalyst particles and semiconductor nanowires were also studied with the goal of achieving photocatalytic water splitting using visible light.

Thomas E. Mallouk

2007-05-27

130

Direct electrochemistry and electrocatalysis of hemoglobin on chitosan-room temperature ionic liquid-TiO 2-graphene nanocomposite film modified electrode  

Microsoft Academic Search

TiO2-graphene nanocomposite was prepared by hydrolysis of titanium isopropoxide in colloidal suspension of graphene oxide and in situ hydrothermal treatment. The direct electrochemistry and electrocatalysis of hemoglobin in room temperature ionic liquid 1-Butyl-3-methylimidazolium hexafluorophosphate, chitosan and TiO2-graphene nanocomposite modified glassy carbon electrode were investigated. The biosensor was examined by using UV-vis spectroscopy, scanning electron microscopy and electrochemical methods. The results

Jun-Yong Sun; Ke-Jing Huang; Su-Fang Zhao; Yang Fan; Zhi-Wei Wu

2011-01-01

131

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.

132

Intimate coupling of photocatalysis and biodegradation in a photocatalytic circulating-bed biofilm reactor.  

PubMed

Coupling advanced oxidative pretreatment with subsequent biodegradation demonstrates potential for treating wastewaters containing biorecalcitrant and inhibitory organic constituents. However, advanced oxidation is indiscriminate, producing a range of products that can be too oxidized, unavailable for biodegradation, or toxic themselves. This problem could be overcome if advanced oxidation and biodegradation occurred together, an orientation called intimate coupling; then, biodegradable organics are removed as they are formed, focusing the chemical oxidant on the non-biodegradable fraction. Intimate coupling has seemed impossible because the conditions of advanced oxidation, for example, hydroxyl radicals and sometimes UV-light, are severely toxic to microorganisms. Here, we demonstrate that a novel photocatalytic circulating-bed biofilm reactor (PCBBR), which utilizes macro-porous carriers to protect biofilm from toxic reactants and UV light, achieves intimate coupling. We demonstrate the viability of the PCBBR system first with UV only and acetate, where the carriers grew biofilm and sustained acetate biodegradation despite continuous UV irradiation. Images obtained by scanning electron microscopy and confocal laser scanning microscopy show bacteria living behind the exposed surface of the cubes. Second, we used slurry-form Degussa P25 TiO2 to initiate photocatalysis of inhibitory 2,4,5-trichlorophenol (TCP) and acetate. With no bacterial carriers, photocatalysis and physical processes removed TCP and COD to 32% and 26% of their influent levels, but addition of biofilm carriers decreased residuals to 2% and 4%, respectively. Biodegradation alone could not remove TCP. Photomicrographs clearly show that biomass originally on the exterior of the carriers was oxidized (charred), but biofilm a short distance within the carriers was protected. Finally, we coated TiO2 directly onto the carrier surface, producing a hybrid photocatalytic-biological carrier. These carriers likewise demonstrated the concept of photocatalytic degradation of TCP coupled with biodegradation of acetate, but continued TCP degradation required augmentation with slurry-form TiO2. PMID:18512737

Marsolek, Michael D; Torres, César I; Hausner, Martina; Rittmann, Bruce E

2008-09-01

133

An adsorption-photocatalysis hybrid process using multi-functional-nanoporous materials for wastewater reclamation.  

PubMed

In this study, two of our recently developed laboratory scale wastewater treatment systems, fluidized-bed reactor (FBR) using formulated clay mixture absorbents (clay-FBR adsorption) and an annular slurry photoreactor (ASP) using TiO(2) impregnated kaolin catalysts (TiO(2)-K-ASP) were integrated as an adsorption-photocatalysis hybrid process to treat municipal wastewater as alternative secondary and tertiary treatment for wastewater reclamation. Primary effluent from sewage and secondary effluent from a membrane bioreactor treatment process were used to assess chemical removal capabilities of the FBR and ASP systems, and the hybrid process. The formulated clays-FBR system demonstrated the prevailing removal efficiency toward PO(4)(3-), NO(3)(-) and suspended solids. The TiO(2)-K-ASP showed superior degradation of dissolved organic content; while the presence of inorganic ions caused a detrimental effect on its performance. The integration of the adsorption and degradation system as a hybrid treatment process resulted in a synergetic enhancement for the chemical removal efficiency. Complete elimination of PO(4)(3-) content was obtained in the adsorption stage; while 30% and 65% NO(3)(-) removal were obtained from the hybrid treatment of the primary and secondary effluents, respectively. The corresponding COD reduction during the photodegradation was further investigated by the high-performance size exclusion chromatography technique, where it revealed the shift of apparent molecular weight of the dissolved organic contaminants toward the smaller region. This present study demonstrated that this adsorption-photocatalysis hybrid technology can be used as a feasible alternative treatment process for wastewater reclamation. PMID:20619869

Vimonses, Vipasiri; Jin, Bo; Chow, Christopher W K; Saint, Christopher

2010-06-22

134

Summary of engineering-scale experiments for the Solar Detoxification of Water project  

Microsoft Academic Search

This report contains a summary of large-scale experiments conducted at Sandia National Laboratories under the Solar Detoxification of Water project. The objectives of the work performed were to determine the potential of using solar radiation to destroy organic contaminants in water by photocatalysis and to develop the process and improve its performance. For these experiments, we used parabolic troughs to

J. E. Pacheco; L. Yellowhorse

1992-01-01

135

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-...

136

Heterogeneous photocatalysis  

Microsoft Academic Search

The presence of transition metal ions in photocatalytic reactions is reviewed according to two main approaches: (a) the influence of transition metal ions on the rate of photocatalytic reactions (mainly oxidation) and (b) the transformation of the ions to less toxic species or their deposition on the semiconductor catalyst surface for recovery of expensive and useful metals. Most of the

Marta I. Litter

1999-01-01

137

DISINFECTION OF MUNICIPAL WASTEWATER BY TiO2 PHOTOCATALYSIS WITH UVA, VISIBLE AND SOLAR IRRADIATION AND BDD ELECTROLYSIS  

Microsoft Academic Search

The efficiency of TiO2 photocatalysis induced by ultraviolet and visible irradiation and salt-free electrolysis over boron-doped diamond electrodes to inactivate total (TC) and fecal (FC) coliforms in secondary treated municipal wastewater was evaluated. Photocatalytic experiments were conducted with two types of titania (Degussa P25 and sulfur-doped catalyst) at loadings in the range 0.1-0.5 g l-1 and three types of irradiation,

M. MELEMENI; D. STAMATAKIS; N. P. XEKOUKOULOTAKIS; D. MANTZAVINOS; N. KALOGERAKIS

138

Synergistic effects of chromium(VI) reduction\\/EDTA oxidization for PCB wastewater by photocatalysis combining ionic exchange membrane processes  

Microsoft Academic Search

A new technology using the TiO2 photocatalysis combining electrodialysis was proposed for the simultaneous oxidization of ethylenediaminetetraacetic acid (EDTA)\\/reduction of hexavalent chromium (Cr(VI)) by electron–hole (e–h) pairs. The application of a cationic exchange membrane in this system was used to enhance the efficiency for the prevention of the recombination of electrons with the electron hole. The following parameters were studied:

Hung-Te Hsu; Shiao-Shing Chen; Wen-Shing Chang; Chi-Wang Li

2012-01-01

139

Structure-dependent electrocatalysis of Ni(OH)2 hourglass-like nanostructures towards L-histidine.  

PubMed

As the properties of nanomaterials are strongly dependent on their size, shape and nanostructures, probing the relations between macro-properties and nanostructures is challenging for nanoscientists. Herein, we deliberately chose three types of Ni(OH)(2) with hexagonal, truncated trigonal, and trigonal hourglass-like nanostructures, respectively, as the electrode modifier to demonstrate the correlation between the nanostructures and their electrocatalytic performance towards L-histidine. It was found that the hexagonal hourglass-like Ni(OH)(2) sample had the best electrocatalytic activity, which can be understood by a cooperative mechanism: on one hand, the hexagonal sample possesses the largest specific surface area and the tidiest nanostructure, resulting in the most orderly packing on the electrode surface; on the other hand, its internal structure with the most stacking faults would generate a lot of unstable protons, leading to an enhanced electronic conductivity. The findings are important because they provide a clue for materials design and engineering to meet a specific requirement for electrocatalysis of L-histidine, possibly even for other biomolecules. In addition, the hexagonal Ni(OH)(2)-based biosensor shows excellent sensitivity and selectivity in the determination of L-histidine and offers a promising feature for the analytical application in real biological samples. PMID:23255517

Nai, Jianwei; Chen, Zhengbo; Li, Haopeng; Li, Fangyuan; Bai, Yang; Li, Lidong; Guo, Lin

2012-12-18

140

The effect of Ru and Sn additions to Pt on the electrocatalysis of methanol oxidation: An in situ XAS investigation  

SciTech Connect

Elements such as Ru and Sn used as ad-atoms or as alloying elements are known to enhance methanol oxidation reaction (MOR). Ru, both as alloying element as well as upd deposited on Pt/C is widely acknowledged for enhancing MOR. Sn on the other hand is more controversial, with evidence indicating enhancements for MOR when present as upd layer and marginally effective when present as an alloying element. In situ XAS is used to investigate some of these inconsistencies in the electrocatalysis of MOR. Results indicate that alloying Sn with Pt (Pt{sub 3}Sn primary phase) causes partial filling of the Pt 5 d-band vacancies and increase in the Pt-Pt bond distances which is directly opposite to a similar situation with Ru. Upd Sn however does not perturb Pt structurally or electronically. Ru and Sn (both as alloying element and as upd ad-layer) are associated with oxygenated species, the nature and strength of the Ru. and Sn - oxygen interactions are potential dependent. Hence alloying with Sn renders Pt surface unfavorable for methanol adsorption in contrast to alloying with Ru. Both Ru and Sn however promote MOR via their ability to nucleate oxygenated species on their surface at lower potentials as compared to pure Pt.

Mukerjee, S.; McBreen, J.

1997-07-01

141

Investigation of the electrocatalysis for oxygen reduction reaction by Pt and binary Pt alloys: an XRD, XAS and electrochemical study  

SciTech Connect

Electrocatalysis for the oxygen reduction reaction (ORR) on five binary Pt alloy electrocatalysts (PtCr/C, PtMn/C, PtFe/C, PtCo/C and PtNi/C) supported on carbon have been investigated. The electrochemical characteristics for ORR in a proton conducting fuel cell environment has been correlated with the electronic and structural parameters determined under in situ conditions using XANES and EXAFS technique respectively. Results indicate that all the alloys possess higher Pt 5d band vacancies as compared to Pt/C. There is also evidence of lattice contraction in the alloys (supported by XRD results). Further, the Pt/C shows increase in Pt 5 d band vacancies during potential transitions from 0.54 to 0.84 V vs. RHE, which has been ration@ on the basis of OH type adsorption. In contrast to this, the alloys do not exhibit such an enhancement. Detailed EXAFS analysis supports the presence of OH species on Pt/C and its relative absence in the alloys. Correlation of the electrochemical results with bond distances and d-band vacancies show a volcano type behavior with the PtCr/C on top of the curve.

Mukerjee, S.; McBreen, J. [Brookhaven National Lab., Upton, NY (United States); Srinivasan, S. [Texas A and M Univ., College Station, TX (United States). Texas Engineering Experiment Station

1995-12-31

142

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

NASA Astrophysics Data System (ADS)

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.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. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03024e

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

2013-09-01

143

Crystalline metallic Au nanoparticle-loaded ?-Bi2O3 microrods for improved photocatalysis.  

PubMed

Crystalline metallic Au nanoparticles were loaded on ?-Bi(2)O(3) microrods (Au/?-Bi(2)O(3)) using an Au deposition-precipitation method. The prepared samples were characterized by scanning electron and transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and UV-vis diffuse reflectance spectroscopy. Upon visible light irradiation, the Au/?-Bi(2)O(3) exhibits much higher photocatalytic activities than the pure ?-Bi(2)O(3) for the degradation of Rhodamine B and 2,4-dichlorophenol in aqueous solution. The role of the Au and the paths of electron transport in the photocatalysis of the Au/?-Bi(2)O(3) were investigated and discussed in detail based on the analysis of the photo-generated hydroxyl radicals (?OH) and hydrogen peroxide (H(2)O(2)) in the visible light irradiated suspension of pure ?-Bi(2)O(3) and Au/?-Bi(2)O(3). The result reveals that the Au loaded on ?-Bi(2)O(3) plays a critical role in the separation of the electron and hole pairs by accumulating the electrons from the excited ?-Bi(2)O(3), which is responsible for the enhanced photocatalytic activity. PMID:22868636

Jiang, Hai-Ying; Cheng, Kun; Lin, Jun

2012-08-07

144

Treatment of textile dyehouse wastewater by TiO2 photocatalysis.  

PubMed

The oxidative degradation of an actual textile dyehouse wastewater was investigated by means of photocatalysis in the presence of TiO2. The UV-A-induced photocatalytic oxidation over TiO2 suspensions was capable of decolorizing the effluent completely, as well as reducing chemical oxygen demand (COD) sufficiently (COD reduction generally varied between about 40% and 90% depending on the operating conditions) after 4 h of treatment. Two crystalline forms of TiO2, viz. anatase and rutile, were tested for their photocatalytic activity and anatase was found to be more active than rutile. The extent of photocatalytic degradation was found to increase with increasing TiO2 concentration up to 0.5 g/L TiO2, above which degradation remained practically constant, reaching a plateau. Furthermore, textile effluent degradation was enhanced at acidic conditions (i.e. pH = 3) and in the presence of hydrogen peroxide. To assess catalyst activity on repeated use, experiments were performed where the catalyst was recovered and reused; after three successive uses, TiO2 had sufficiently retained its photocatalytic activity. Finally, the luminescent marine bacteria Vibrio fischeri was used to assess the acute ecotoxicity of samples prior to and after the photocatalytic treatment and it was found that ecotoxicity was fully eliminated following photocatalytic oxidation. PMID:16510167

Pekakis, Pantelis A; Xekoukoulotakis, Nikolaos P; Mantzavinos, Dionissios

2006-02-28

145

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

2013-09-26

146

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

147

Heterogeneous photo-catalysis system for the degradation of azo dye Reactive Black 5 (RB5).  

PubMed

This study investigated a heterogeneous photo-catalysis system by introducing a novel brick supported iron oxide (denoted as B1) for the heterogeneous photoassisted degradation of Reactive Black 5 (RB5) at pH value from 3 to 7 in a three-phase (gas-liquid-solid) fluidized bed reactor (3P-FBR). Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD) and N(2) adsorption/desorption were used to characterize the B1 catalyst. The in situ formation of hydrogen peroxide and the depletion of oxalic acid by photochemical cycle of Fe(III)-oxalate complex under UVA light (? = 365 nm) were studied. The effects of the solution pH and the concentration of oxalic acid on the degradation of RB5 are elucidated. About 90% decolourization was measured and 80% of the total organic carbon (TOC) was eliminated at pH 5.0 after 120 min for 20 mg/L RB5 in presence of 10 g/L B1 catalyst, 30 mg/L oxalic acid under 15 W UVA light. A mechanism for the photocatalytic degradation of RB5 over B1 catalyst is proposed. PMID:22233898

Huang, Yao-Hui; Wei, Hau-Cheng; Chen, Hung-Ta

2012-01-01

148

Porous ZnO-ZnSe nanocomposites for visible light photocatalysis.  

PubMed

We report the synthesis of porous ZnO-ZnSe nanocomposites for use in visible light photocatalysis. Porous ZnO nanostructures were synthesized by a microwave-assisted hydrothermal reaction then converted into porous ZnO-ZnSe nanocomposites by a microwave-assisted dissolution-recrystallization process using an aqueous solution containing selenium ions. ZnO and ZnSe nanocrystallites of the nanocomposites were well-mixed (rather than forming simple core-shell (ZnO-ZnSe) structures), particularly, in the outer regions. Both ZnO and ZnSe were present at the surface and exposed to the environment. The porous ZnO-ZnSe nanocomposites showed absorption bands in the visible region as well as in the UV region. The porous ZnO-ZnSe nanocomposites had much higher activities than the porous ZnO nanostructures. Control experiments using cutoff filters revealed that the main photocatalytic activity of the synthesized nanostructures arose from photo-excitation of the semiconductor (ZnO or ZnSe) via absorption of light of an energy equal to or exceeding the band gap energy. PMID:22337249

Cho, Seungho; Jang, Ji-Wook; Lee, Jae Sung; Lee, Kun-Hong

2012-02-16

149

TiO2-assisted photo-catalysis degradation process of dye chemicals.  

PubMed

The photo-catalytic degradation pathway and degradation products of methylene blue, rhodamine B, methyl orange, and malachite green in aqueous TiO2 suspension irradiated by high pressure mercury lamp by means of UV-visible absorption spectra and ion chromatography were investigated. The photo-catalysis degradation of dye solutions with charges was greatly effected by pH value owing to the electrostatic model. The photo-degradation rate of dyes anion increased with the decrease of pH value, in contrast, the photo-degradation rate of dyes cation increased with the increase of pH value. And the absorption peaks diminished with a blue shift. After illuminated for 30 minutes, a part of dye chemicals were completely mineralized and transferred into inorganic species including chloride ion, ammonium ion, nitrate ion, sulfate ion. And the addition of 100 mmol/L H2O2 promoted the formation of inorganic species. In this study, the quantity of ammonium ion was much more than that of nitrate ion. That indicated the formation of nitrate is from ammonium. The purification rate of COD in four kinds of dye solution was 71.7%-88.7%. The decrease of COD of dyes solution implies the feasibility of the environmental application of photo-catalyzed process. PMID:11590721

Li, F B; Gu, G B; Huang, G F; Gu, Y L; Wan, H F

2001-01-01

150

TiO2-Based Advanced Oxidation Nanotechnologies For Water Purification And Reuse  

EPA Science Inventory

TiO2 photocatalysis, one of the UV-based advanced oxidation technologies (AOTs) and nanotechnologies (AONs), has attracted great attention for the development of efficient water treatment and purification systems due to the effectiveness of TiO2 to generate ...

151

The feasibility of using combined TiO 2 photocatalysis-SBR process for antibiotic wastewater treatment  

Microsoft Academic Search

The study examined the feasibility of using combined TiO2 photocatalysis (UV\\/TiO2\\/H2O2) and sequencing batch biological reactor (SBR) process for treatment of an antibiotic wastewater containing amoxicillin and cloxacillin. In the first part of the study, the effect of TiO2 and H2O2 dose on the UV\\/TiO2\\/H2O2 process was evaluated. The best TiO2 and H2O2 dose were observed to be 1000 and

Emad S. Elmolla; Malay Chaudhuri

2011-01-01

152

Self-doping and surface plasmon modification induced visible light photocatalysis of BiOCl  

NASA Astrophysics Data System (ADS)

In this study we demonstrate that self-doping and surface plasmon resonance could endow a wide-band-gap ternary semiconductor BiOCl with remarkable visible light driven photocatalytic activity on the degradation of organic pollutants and photocurrent generation properties. The self-doped BiOCl with plasmonic silver modification was synthesized by a facile one-pot nonaqueous approach and systematically characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-visible diffuse reflectance spectra, electron spin resonance, and X-ray photoelectron spectroscopy. The photocurrent enhancement was found to be intimately dependent on the irradiation wavelength and matched well with the intensity of the absorption of the Ag nanoparticles. Reactive species trapping experiments and electron spin resonance spectroscopy with 5,5-dimethyl-1-pyrroline-N-oxide spin-trapping adducts confirmed that more oxidative species could be generated from the photogenerated electrons due to the plasmon-excitation of the metallic Ag in the self-doped BiOCl with plasmonic silver modification, which is responsible for the great enhancement of photocatalytic activity and photocurrent. Surface photovoltage spectroscopy and time-resolved photoluminescence spectroscopy results revealed the transfer of plasmon-band-induced electrons from Ag nanoparticles into BiOCl and the acceleration effect of surface plasmon resonance-induced intense oscillating electric fields on this electron transfer. This study would not only provide direct evidence of plasmonic photocatalysis, but also shed light on the design of highly efficient metal-semiconductor composite photocatalysts.In this study we demonstrate that self-doping and surface plasmon resonance could endow a wide-band-gap ternary semiconductor BiOCl with remarkable visible light driven photocatalytic activity on the degradation of organic pollutants and photocurrent generation properties. The self-doped BiOCl with plasmonic silver modification was synthesized by a facile one-pot nonaqueous approach and systematically characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-visible diffuse reflectance spectra, electron spin resonance, and X-ray photoelectron spectroscopy. The photocurrent enhancement was found to be intimately dependent on the irradiation wavelength and matched well with the intensity of the absorption of the Ag nanoparticles. Reactive species trapping experiments and electron spin resonance spectroscopy with 5,5-dimethyl-1-pyrroline-N-oxide spin-trapping adducts confirmed that more oxidative species could be generated from the photogenerated electrons due to the plasmon-excitation of the metallic Ag in the self-doped BiOCl with plasmonic silver modification, which is responsible for the great enhancement of photocatalytic activity and photocurrent. Surface photovoltage spectroscopy and time-resolved photoluminescence spectroscopy results revealed the transfer of plasmon-band-induced electrons from Ag nanoparticles into BiOCl and the acceleration effect of surface plasmon resonance-induced intense oscillating electric fields on this electron transfer. This study would not only provide direct evidence of plasmonic photocatalysis, but also shed light on the design of highly efficient metal-semiconductor composite photocatalysts. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03597b

Jiang, Jing; Zhang, Lizhi; Li, Hao; He, Weiwei; Yin, Jun Jie

2013-10-01

153

Self-doping and surface plasmon modification induced visible light photocatalysis of BiOCl.  

PubMed

In this study we demonstrate that self-doping and surface plasmon resonance could endow a wide-band-gap ternary semiconductor BiOCl with remarkable visible light driven photocatalytic activity on the degradation of organic pollutants and photocurrent generation properties. The self-doped BiOCl with plasmonic silver modification was synthesized by a facile one-pot nonaqueous approach and systematically characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-visible diffuse reflectance spectra, electron spin resonance, and X-ray photoelectron spectroscopy. The photocurrent enhancement was found to be intimately dependent on the irradiation wavelength and matched well with the intensity of the absorption of the Ag nanoparticles. Reactive species trapping experiments and electron spin resonance spectroscopy with 5,5-dimethyl-1-pyrroline-N-oxide spin-trapping adducts confirmed that more oxidative species could be generated from the photogenerated electrons due to the plasmon-excitation of the metallic Ag in the self-doped BiOCl with plasmonic silver modification, which is responsible for the great enhancement of photocatalytic activity and photocurrent. Surface photovoltage spectroscopy and time-resolved photoluminescence spectroscopy results revealed the transfer of plasmon-band-induced electrons from Ag nanoparticles into BiOCl and the acceleration effect of surface plasmon resonance-induced intense oscillating electric fields on this electron transfer. This study would not only provide direct evidence of plasmonic photocatalysis, but also shed light on the design of highly efficient metal-semiconductor composite photocatalysts. PMID:24056871

Jiang, Jing; Zhang, Lizhi; Li, Hao; He, Weiwei; Yin, Jun Jie

2013-09-19

154

Silver decorated titanate/titania nanostructures for efficient solar driven photocatalysis  

SciTech Connect

Photocatalysis has attracted significant interest to solve both the energy crisis and effectively combat environmental contamination. However, as the most widely used photocatalyst, titania (TiO{sub 2}) suffers from inefficient utilization of solar energy due to its wide band gap. In the present paper, we describe a method to extend the absorption edge of photocatalyst to visible region by the surface plasmon effect of silver. Silver ions are photo-reduced onto the surface of titanate nanotubes, which are synthesized by a conventional hydrothermal method. The as-synthesized Ag/titanate composite is transformed into Ag/titania nanoparticles by annealing at different temperatures. It is found that the interaction of Ag nanoparticles with the supports (titanate/titania) plays a key role for the visible light activity. The samples annealed at low temperature (<350 Degree-Sign C) do not show significant activity under our conditions, while the one annealed at 450 Degree-Sign C shows fast-degradation of methyl orange (MO) under visible light irradiation. The detailed mechanisms are also discussed. - Graphical abstract: Silver nanoparticles decorated titanate/titania as visible light active photocatalysts: silver nanoparticles could be excited by visible light due to its surface plasmon effect and excited electrons could be transferred to the conduction band of the semiconductor, where the reduction process occurs. Highlights: Black-Right-Pointing-Pointer Uniform Ag nanoparticles are photo-reduced onto titanate and titania nanostructures. Black-Right-Pointing-Pointer Titania crystal is formed by annealing hydrogen titanate at different temperatures. Black-Right-Pointing-Pointer Best visible-light activity is achieved by Ag-loaded titania annealed at 450 Degree-Sign C. Black-Right-Pointing-Pointer The visible light activity is attributed to the surface plasmonic resonance effect.

Gong, Dangguo [School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Heterogeneous Catalysis Technology, Institute of Chemical and Engineering Sciences, 1 Pesek Road, Singapore 627833 (Singapore); Ho, Weng Chye Jeffrey; Tang Yuxin; Tay Qiuling; Lai Yuekun [School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Highfield, James George, E-mail: james_highfield@ices.a-star.edu.sg [Heterogeneous Catalysis Technology, Institute of Chemical and Engineering Sciences, 1 Pesek Road, Singapore 627833 (Singapore); Chen Zhong, E-mail: aszchen@ntu.edu.sg [School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

2012-05-15

155

Photochemical transformations of water-soluble fraction (WSF) of crude oil in marine waters  

Microsoft Academic Search

Changes in the chemical nature of the water-soluble fraction (WSF) of crude oils caused by photolysis and heterogeneous photocatalysis using TiO2 were investigated by gas chromatography–mass spectrometry (GC–MS) and ultraviolet fluorescence spectrophotometry (UVF). Two Brazilian crude oil samples with different concentrations of WSF (45 and 15mgCl?1) were studied. Photochemical driven reactions were investigated under UV-Vis irradiation in the absence and

Roberta L. Ziolli; Wilson F. Jardim

2003-01-01

156

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

2012-09-18

157

Removal and Destruction of Organic Contaminants in Water Using Adsorption, Steam Regeneration, and Photocatalytic Oxidation: A Pilot-Scale Study  

Microsoft Academic Search

The overall objective of this pilot-scale study is to investigate the technical feasibility of the removal and destruction of organic contaminants in water using adsorption and photocatalytic oxidation. The process consists of two consecutive operational steps: (1) removal of organic contaminants using fixed-bed adsorption; and (2) regeneration of spent adsorbent using photocatalysis or steam, followed by decontamination of steam condensate

Rominder P. S. Suri; Junbiao Liu; John C. Crittenden; David W. Hand

1999-01-01

158

Pilot-plant treatment of olive mill wastewater (OMW) by solar TiO 2 photocatalysis and solar photo-Fenton  

Microsoft Academic Search

Olive mill wastewater (OMW), a highly polluted wastewater from the olive oil industry, was treated by solar photocatalysis and solar photo-Fenton. Among the tested systems the application of titanium dioxide alone was not successful. The addition of peroxydisulphate as an electron acceptor had only limited effect on degradation performance and led to high salt concentrations (30 g\\/l sulphate generated) and

W. Gernjak; M. I. Maldonado; S. Malato; J. Cáceres; T. Krutzler; A. Glaser; R. Bauer

2004-01-01

159

Electrocatalysis of oxygen reduction by chalcogenides containing mixed transition metal clusters  

Microsoft Academic Search

A new class of catalysts for the reduction of molecular oxygen to water in acid environment has been discovered, which show eletrocatalytical activity comparable to that of platinum. They are Chevrel type chalcogenides with the stoichiometry Mo\\/sub 6-x\\/M\\/sub x\\/Xâ (M = transition metal, X = chalcogen atom), containing octahedral mixed-metal clusters of transition-metal atoms. Experimental data obtained with rotating disk

N. Alonso Vante; W. Jaegermann; H. Tributsch; W. Hoenle; K. Yvon

1987-01-01

160

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

161

One-step synthesis of graphene/polyallylamine-Au nanocomposites and their electrocatalysis toward oxygen reduction.  

PubMed

A simple, inexpensive, one-step synthesis of graphene/PAA-Au nanocomposites was achieved by using polyallylamine (PAA) as a reducing and stabilizing agent. The synthetic process was carried out only in aqueous solution, which is versatile and environmentally friendly. The resulting nanocomposites could be dispersed into water stably without any additional protection by polymeric or surfactant stabilizers. The products were further characterized by UV-visible absorption spectroscopy, transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FTIR) and photoelectron spectroscopy (XPS). The results indicate that graphene sheets played an important role as a support material to increase the active area of Au nanoparticles (AuNPs). And the resulting graphene/PAA-Au nanocomposites film exhibited good electrocatalytical activity towards reduction of both H(2)O(2) and O(2), which showed potential application in electrochemical sensors. PMID:22284507

Zhang, Qixian; Ren, Qiaoqiao; Miao, Yuqing; Yuan, Junhua; Wang, Kaikai; Li, Fenghua; Han, Dongxue; Niu, Li

2011-12-23

162

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

163

Substrate Fermi level effects in photocatalysis on oxides: Properties of ultrathin TiO{sub 2}/Si films  

SciTech Connect

Photocatalysis has widespread applications from solar cells to photolithography. We studied the photocatalytic properties of TiO{sub 2} films of thicknesses down to 2 nm, grown on n-type and p-type silicon wafers, using the oxidation of isopropanol as a model system. Direct in vacuo mass spectrometry measurements were performed under irradiation above the TiO{sub 2} bandgap. We present a model consistent with our experimental results, which indicate that only near-surface electron-hole pair generation is relevant and that the reaction rate can be controlled by varying the substrate Fermi level in going from n-type to p-type silicon, by approximately a factor of 2.

Kazazis, D.; Zaslavsky, A. [Division of Engineering, Brown University, Providence, Rhode Island 02912 (United States); Guha, S.; Bojarczuk, N. A. [IBM T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States); Kim, H.-C. [IBM Almaden Research Center, San Jose, California 95120 (United States)

2009-08-10

164

Photocatalysis and wave-absorbing properties of polyaniline/TiO 2 microbelts composite by in situ polymerization method  

NASA Astrophysics Data System (ADS)

Polyaniline (PANI)/TiO 2 composite is prepared by in situ polymerization of polyaniline on the surface of TiO 2 template obtained by the sol-gel process via cotton template. The TiO 2 microbelts are prepared by sol-gel method using the absorbent cotton as template for the first time. Then the TiO 2 microtubules are used as template for the preparation of polyaniline/TiO 2 composites. The structure, morphology and properties of the composites are characterized with scanning electron microscope (SEM), IR, Net-wok Analyzer. A possible formation mechanism of TiO 2 microtubules and polyaniline/TiO 2 composites has been proposed. The effect of the mol ratio of polyaniline/TiO 2 on the microwave loss properties and photocatalysis properties of the composites is investigated.

Li, Qiaoling; Zhang, Cunrui; Li, Jianqiang

2010-11-01

165

Energy efficiency for the removal of non-polar pollutants during ultraviolet irradiation, visible light photocatalysis and ozonation of a wastewater effluent.  

PubMed

This study aims to assess the removal of a set of non-polar pollutants in biologically treated wastewater using ozonation, ultraviolet (UV 254 nm low pressure mercury lamp) and visible light (Xe-arc lamp) irradiation as well as visible light photocatalysis using Ce-doped TiO2. The compounds tracked include UV filters, synthetic musks, herbicides, insecticides, antiseptics and polyaromatic hydrocarbons. Raw wastewater and treated samples were analyzed using stir-bar sorptive extraction coupled with comprehensive two-dimensional gas chromatography (SBSE-CG × GC-TOF-MS). Ozone treatment could remove most pollutants with a global efficiency of over 95% for 209 ?M ozone dosage. UV irradiation reduced the total concentration of the sixteen pollutants tested by an average of 63% with high removal of the sunscreen 2-ethylhexyl trans-4-methoxycinnamate (EHMC), the synthetic musk 7-acetyl-1,1,3,4,4,6-hexamethyltetrahydronaphthalene (tonalide, AHTN) and several herbicides. Visible light Ce-TiO2 photocatalysis reached ?70% overall removal with particularly high efficiency for synthetic musks. In terms of power usage efficiency expressed as nmol kJ(-1), the results showed that ozonation was by far the most efficient process, ten-fold over Xe/Ce-TiO2 visible light photocatalysis, the latter being in turn considerably more efficient than UV irradiation. In all cases the efficiency decreased along the treatments due to the lower reaction rate at lower pollutant concentration. The use of photocatalysis greatly improved the efficiency of visible light irradiation. The collector area per order decreased from 9.14 ± 5.11 m(2) m(-3) order(-1) for visible light irradiation to 0.16 ± 0.03 m(2) m(-3) order(-1) for Ce-TiO2 photocatalysis. The toxicity of treated wastewater was assessed using the green alga Pseudokirchneriella subcapitata. Ozonation reduced the toxicity of treated wastewater, while UV irradiation and visible light photocatalysis limited by 20-25% the algal growth due to the accumulation of reaction by-products. Three transformation products were identified and tracked along the treatments. PMID:23863371

Santiago-Morales, Javier; Gómez, María José; Herrera-López, Sonia; Fernández-Alba, Amadeo R; García-Calvo, Eloy; Rosal, Roberto

2013-06-25

166

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

167

Amperometric biosensor for hydrogen peroxide based on direct electrocatalysis by hemoglobin immobilized on gold nanoparticles/1,6-diaminohexane modified glassy carbon electrode.  

PubMed

A facile strategy of an amperometric biosensor for hydrogen peroxide based on the direct electrocatalysis of hemoglobin (Hb) immobilized on gold nanoparticles (GNPs)/1,6-diaminohexane (DAH) modified glassy carbon electrode (GCE) has been described. A uniform monolayer film of DAH was initially covalently bound on a GCE surface by virtue of the electrooxidation of one amino group of DAH, and another amino group was modified with GNPs and Hb, successively. The fabrication process was characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The proposed biosensor exhibited an effective and fast catalytic response to the reduction of H2O2 with good reproducibility and stability. A linear relationship existed between the catalytic current and the H2O2 concentration in the range of 1.5x10(-6) to 2.1x10(-3) M with a correlation coefficient of 0.998 (n=24). The detection limit (S/N=3) was 8.8x10(-7) M. PMID:18403840

Tang, Mingyu; Chen, Shihong; Yuan, Ruo; Chai, Yaqin; Gao, Fengxian; Xie, Yi

2008-04-01

168

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

NASA Astrophysics Data System (ADS)

CdS hollow microspheres have been successfully prepared by a photochemical preparation technology at room temperature, using polystyrene latex particles as templates, CdSO4 as cadmium source and Na2S2O3 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 H2O2. The method is green, simple, universal and can be extended to prepare other sulphide and oxide hollow spheres.Graphical abstractTaking 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

Huang, Yuying; Sun, Fengqiang; Wu, Tianxing; Wu, Qingsong; Huang, Zhong; Su, Heng; Zhang, Zihe

2011-03-01

169

Biomineralized N-doped CNT/TiO2 core/shell nanowires for visible light photocatalysis.  

PubMed

We report an efficient and environmentally benign biomimetic mineralization of TiO(2) at the graphitic carbon surface, which successfully created an ideal TiO(2)/carbon hybrid structure without any harsh surface treatment or interfacial adhesive layer. The N-doped sites at carbon nanotubes (CNTs) successfully nucleated the high-yield biomimetic deposition of a uniformly thick TiO(2) nanoshell in neutral pH aqueous media at ambient pressure and temperature and generated N-doped CNT (NCNT)/TiO(2) core/shell nanowires. Unlike previously known organic biomineralization templates, such as proteins or peptides, the electroconductive and high-temperature-stable NCNT backbone enabled high-temperature thermal treatment and corresponding crystal structure transformation of TiO(2) nanoshells into the anatase or rutile phase for optimized material properties. The direct contact of the NCNT surface and TiO(2) nanoshell without any adhesive interlayer introduced a new carbon energy level in the TiO(2) band gap and thereby effectively lowered the band gap energy. Consequently, the created core/shell nanowires showed a greatly enhanced visible light photocatalysis. Other interesting synergistic properties such as stimuli-responsive wettabilites were also demonstrated. PMID:22195985

Lee, Won Jun; Lee, Ju Min; Kochuveedu, Saji Thomas; Han, Tae Hee; Jeong, Hu Young; Park, Moonkyu; Yun, Je Moon; Kwon, Joon; No, Kwangsoo; Kim, Dong Ha; Kim, Sang Ouk

2011-12-29

170

Characterization and photocatalysis of Eu{sup 3+}-TiO{sub 2} sol in the hydrosol reaction system  

SciTech Connect

In this paper, 3.0 mol% lanthanide europium ion modified TiO{sub 2} sol (Eu{sup 3+}-TiO{sub 2}) was fabricated by chemical coprecipitation-peptization method with TiCl{sub 4} as precursor. Eu{sup 3+}-TiO{sub 2} sol particles were characterized by X-ray diffraction (XRD), atomic force microscope (AFM), transmission electron microscope (TEM) and particle size distribution (PSD). Eu{sup 3+}-TiO{sub 2} sol particles prepared at low temperature (70 deg. C) had anatase semicrystalline structure. Eu{sup 3+}-TiO{sub 2} sol sample homogeneously dispersed in the aqueous medium and presented narrow distribution characterization with 7 nm in mean size. Interfacial adsorption experiment shows that small particle size and positive charge of sol particles contributed to the good adsorption of X-3B dye on the TiO{sub 2} surface. The photoelectrochemical property was investigated about electrons transfer efficiency between dye molecule and TiO{sub 2} particles. A novel hydrosol reaction system was designed to conduct X-3B photodegradation reaction. The excellent photocatalytic activity for X-3B degradation under visible light irradiation was ascribed to effective scavenging electrons by Eu{sup 3+} ion. Moreover, X-3B photocatalytic degradation mechanism under visible light excitation was proposed as photosensitization-photocatalysis.

Xie Yibing; Yuan Chunwei

2004-04-02

171

Hematoporphyrin-ZnO nanohybrids: twin applications in efficient visible-light photocatalysis and dye-sensitized solar cells.  

PubMed

Light-harvesting nanohybrids (LHNs) are systems composed of an inorganic nanostructure associated with an organic pigment that have been exploited to improve the light-harvesting performance over individual components. The present study is focused on developing a potential LHN, attained by the functionalization of dense arrays of ZnO nanorods (NRs) with a biologically important organic pigment hematoporphyrin (HP), which is an integral part of red blood cells (hemoglobin). Application of spectroscopic techniques, namely, Fourier transform infrared spectroscopy (FTIR) and Raman scattering, confirm successful monodentate binding of HP carboxylic groups to Zn(2+) located at the surface of ZnO NRs. Picosecond-resolved fluorescence studies on the resulting HP-ZnO nanohybrid show efficient electron migration from photoexcited HP to the host ZnO NRs. This essential photoinduced event activates the LHN under sunlight, which ultimately leads to the realization of visible-light photocatalysis (VLP) of a model contaminant Methylene Blue (MB) in aqueous solution. A control experiment in an inert gas atmosphere clearly reveals that the photocatalytic activity is influenced by the formation of reactive oxygen species (ROS) in the media. Furthermore, the stable LHNs prepared by optimized dye loading have also been used as an active layer in dye-sensitized solar cells (DSSCs). We believe these promising LHNs to find their dual applications in organic electronics and for the treatment of contaminant wastewater. PMID:23186038

Sarkar, Soumik; Makhal, Abhinandan; Bora, Tanujjal; Lakhsman, Karthik; Singha, Achintya; Dutta, Joydeep; Pal, Samir Kumar

2012-12-07

172

Controlled synthesis of SnO2 nanostructures with different morphologies and the influence on photocatalysis properties  

NASA Astrophysics Data System (ADS)

SnO2 nanoparticles, nanoflowers, and nanorods of highly crystalline were synthesized via a simple hydrothermal method. The size and morphology of the SnO2 nanostructures could be controlled by varying the NaOH concentration of the precursor solutions. The SnO2 structures appeared to be sphere-like nanoparticles with diameters in the range of 5-10 nm in lower NaOH concentrations. In higher NaOH concentrations, the nanostructures showed orientation growth behavior and were flower-like or rod-like in morphology. The sphere-like shape demonstrated that Ostwald ripening took effect only at lower NaOH concentration while the preferential growth behavior at higher NaOH concentration testified ``oriented attachment'' was more suitable under this condition. Photocatalysis experiments were carried out to study the influence of the morphology, size, and surface on photocatalytic activities of SnO2. The nanoparticles synthesized with the MNaOH:MSnCl4 = 4:1 showed the highest photolytic activities owing to their tiny size, large surface area, and abundant defect-related energy states.

Guan, Mengmeng; Zhao, Xiaoru; Duan, Libing; Cao, Mengmeng; Guo, Wenrui; Liu, Jinru; Zhang, Wei

2013-09-01

173

From the Fundamentals of Photocatalysis to its Applications in Environment Protection and in Solar Purification of Water in Arid Countries  

Microsoft Academic Search

A specially designed titania photocatalyst was prepared by coating Ahlstrom non-woven paper, used as a flexible photocatalytic support, with Millennium PC500 anatase. At the same time, a new solar photoreactor (STEP) was designed based on the multi-step cascade falling-film principle to ensure a good exposure to sunlight and a good oxygenation of the effluent to be treated. Several types of

Thu Hoai Bui; Eric Puzenat; Chantal Guillard; Bâtiment J. Raulin

174

Separation of titanium dioxide from photocatalytically treated water by cross-flow microfiltration  

Microsoft Academic Search

This study focuses on the separation of titanium dioxide from water by cross-flow microfiltration (CMF) within wastewater treatment by photocatalysis using slurry reactor systems. The systematic studies have shown that the separation performance of TiO2 particles is strongly affected by cross-flow velocity, transmembrane pressure, feed concentration, pH of the suspension and ionic strength. An extreme sensitivity to pH and electrolyte

Weimin XI; Sven-uwe Geissen

2001-01-01

175

Efficient oxidative debromination of decabromodiphenyl ether by TiO2-mediated photocatalysis in aqueous environment.  

PubMed

Direct evidence was first demonstrated for the oxidative degradation of decabromodiphenyl ether (BDE209) in aqueous TiO(2) dispersions under UV irradiation (? > 340 nm). BDE209 was hardly debrominated over TiO(2) in UV-irradiated acetonitrile dispersions, but the addition of water into the dispersions greatly enhanced its photocatalytic oxidative debromination. The debromination efficiency of BDE209 as high as 95.6% was achieved in aqueous TiO(2) dispersions after 12 h of UV irradiation. The photocatalytic oxidation of BDE209 resulted in generation of aromatic ring-opening intermediates such as brominated dienoic acids, which were further degraded by prolonging UV irradiation time. The photocatalytic oxidative debromination of BDE209 was further confirmed by the observation that the BDE209 degradation in water-acetonitrile mixtures with different water contents was positively correlated with the formation of •OH radicals, but not photogenerated electrons. The use of water not only avoided the scavenging of reactive radicals by organic solvent but also enhanced the adsorption of BDE209 on the surface of TiO(2), both of which favor the contact of BDE209 with photogenerated holes and •OH species. The confirmation of efficient oxidative degradation and debromination of BDE209 is very important for finding new ways to remove polybrominated diphenyl ethers from the environment. PMID:23199337

Huang, Aizhen; Wang, Nan; Lei, Ming; Zhu, Lihua; Zhang, Yingying; Lin, Zhifen; Yin, Daqiang; Tang, Heqing

2012-12-18

176

Water  

NSDL National Science Digital Library

Perhaps the single most critical element of the Earth system is water, the carrier and bearer of life that is inextricably woven into the fabric of the Earth system. Only on Earth does water occur in equilibrium ...

177

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

178

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 -0.151V (HRP), -0.167V (Hb), -0.155V (Mb) and -0.193V (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

2013-04-12

179

Visible light photocatalysis via nano-composite CdS\\/TiO2 materials  

Microsoft Academic Search

Nano-structured colloidal semiconductors with heterogeneous photocatalytic behavior have drawn considerable attention over the past few years. This is due to their large surface area, high redox potential of the photogenerated charge carriers and selective reduction\\/oxidation of different class of organic compounds. Nano-structured TiO2 is widely used as a photocatalyst for the effective decomposition of organic compounds in air and water

Sesha S. Srinivasan; Jeremy Wade; Elias K. Stefanakos

180

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

181

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.

182

Water  

MedlinePLUS

... have Web sites that include data on drinking water quality, including results of lead testing. Links to such data can be found at the following EPA Web site: ... Elevated Lead in Tap Water---District of Columbia, 2004 . MMWR. April 2, 2004; ...

183

Band-engineered SrTiO3 nanowires for visible light photocatalysis  

NASA Astrophysics Data System (ADS)

We have theoretically investigated the structural, electronic, and optical properties of perovskite SrTiO3 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 SrTiO3 nanowires compared with that of the bulk. For TiO2-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 SrTiO3 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.

2012-11-01

184

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

185

Multi-walled carbon nanotube supported Pd and Pt nanoparticles with high solution affinity for effective electrocatalysis  

Microsoft Academic Search

Multi-walled carbon nanotubes (MWCNTs) are easily wrapped with a functional biopolymer—polydopamine (Pdop) through self-polymerization of dopamine in a mild basic solution. The MWCNTs@Pdop exhibits long term dispersivity in water for at least one month. The Pdop has large capacity to coordinate [PdCl4]2? and [PtCl6]2? that upon reduction transform to corresponding metal nanoparticles. The nanoparticles strongly adhere to Pdop layer and

Weichun Ye; Haiyuan Hu; Hong Zhang; Feng Zhou; Weimin Liu

2010-01-01

186

Investigations of the effects of photocatalysis on the molecular assembly behavior of titanium alkoxide materials  

NASA Astrophysics Data System (ADS)

The present work focuses on the use of engineered, photoactive metal alkoxide precursors in the sol-gel processing of metal-oxide materials. The strategy under investigation seeks to integrate photoinduced structural modification with conventional sol-gel chemical preparations to enable the selective photo-activation of reaction points about the metal center during material formation. The approach thus has the potential to influence the development of intermolecular bonding geometry and to provide an opportunity to enforce or bias longer range structural development processes and resulting network topology. This ability to bias the long range structural development has been shown to provide opportunities both for photoinduced material formation and the potential to control multi-length scale structural characteristics of these materials. The response of a mononuclear, heteroleptic titanium alkoxide (OPy) 2Ti(4MP)2 [where OPy = pyridine carbinoxide and 4MP = 4-mercaptophenoxide] to ultraviolet (UV) irradiation in dilute solution and in solid-state samples has been measured. Vibrational spectroscopy (FTIR absorption and Raman scattering) was used to monitor changes in molecular structure upon exposure to 337.1 and 365 nm light. Assignment of spectral features to vibrational modes of the molecule was aided by a normal-mode analysis of the energy-minimized molecular structure within a density functional theory (DFT) framework. Photoinduced decreases in peak areas were observed in both FTIR spectra of the precursor solutions and Raman data collected from solution-cast films of the precursor material. These changes were associated with vibrational modes localized at the 4MP ligands. Conversely, no significant modification of vibrational structure associated with the OPy moiety was observed under the excitation conditions examined. Excitation, with 248 nm light, of a solution of (OPy)2Ti(TAP) 2 [where OPy = pyridine carbinoxide and TAP = 2,4,6 tris(dimethylamino)phenoxide] in watercontaining pyridine has been shown to create an insoluble photoproduct in the region of the incident laser beam. Analysis of the photoproduct by Raman spectroscopy indicates the presence of hydrolysis and condensation products as well as features consistent with the unreacted metal alkoxide, indicating destabilization of the alkoxide material that leads to intermolecular linking reactions. Further analysis indicates that it is excitations resonant with the pi -- pi* transitions in the aromatic ligands, as well as in the solvent, that provide this destabilization rather than excitations resonant with the charge transfer band in the molecule. These fundamental studies of the intrinsic molecular-level response of (OPy)2Ti(TAP)2 to ultraviolet irradiation have lead to the development of a novel thin film deposition process wherein the film is deposited directly from solution onto a substrate only in the regions in which it is exposed to ultraviolet light. The nanoscale porosity of films deposited from solution using this technique was found to be dependent on the chemistry of the precursor solution used, with a 1 part addition of water to the precursor producing films with 100 nm diameter surface pores, and an 8 part addition of water to the precursor producing films with no visible surface porosity. Post-deposition thermal treatments have been explored as a means to modify the as-deposited chemistry and nanostructure of the photodeposited films. Films that were fired to 350°C under an oxygen atmosphere no longer showed FTIR features corresponding to ligand-based vibrational modes, with the Raman spectrum of the material showing an increase in the wavenumber range that is indicative of Ti-O-Ti bonding, leading to the conclusion that the residual alkoxide ligands had been removed. In contrast films fired to this temperature under argon showed Raman features assigned to graphite-like structures, indicating that the reducing atmosphere led to the retention of the phenyl moieties in the fired films. The experimental results obtained from optical spectroscopy

Musgraves, Jonathan David

187

Facile synthesis of thermal- and photostable titania with paramagnetic oxygen vacancies for visible-light photocatalysis.  

PubMed

A novel dopant-free TiO(2) photocatalyst (V(o)(.)-TiO(2)), which is self-modified by a large number of paramagnetic (single-electron-trapped) oxygen vacancies, was prepared by calcining a mixture of a porous amorphous TiO(2) precursor, imidazole, and hydrochloric acid at elevated temperature (450 °C) in air. Control experiments demonstrate that the porous TiO(2) precursor, imidazole, and hydrochloric acid are all necessary for the formation of V(o)(.)-TiO(2). Although the synthesis of V(o)(.)-TiO(2) originates from such a multicomponent system, this synthetic approach is facile, controllable, and reproducible. X-ray diffraction, XPS, and EPR spectroscopy reveal that the V(o)(.)-TiO(2) material with a high crystallinity embodies a mass of paramagnetic oxygen vacancies, and is free of other dopant species such as nitrogen and carbon. UV/Vis diffuse-reflectance spectroscopy and photoelectrochemical measurement demonstrate that V(o)(.)-TiO(2) is a stable visible-light-responsive material with photogenerated charge separation efficiency higher than N-TiO(2) and P25 under visible-light irradiation. The V(o)(.)-TiO(2) material exhibits not only satisfactory thermal- and photostability, but also superior photocatalytic activity for H(2) evolution (115 ?mol h(-1) g(-1)) from water with methanol as sacrificial reagent under visible light (?>400 nm) irradiation. Furthermore, the effects of reaction temperature, ratio of starting materials (imidazole:TiO(2) precursor) and calcination time on the photocatalytic activity and the microstructure of V(o)(.)-TiO(2) were elucidated. PMID:23307339

Zou, Xiaoxin; Liu, Jikai; Su, Juan; Zuo, Fan; Chen, Jiesheng; Feng, Pingyun

2013-01-10

188

Visible light Cr(VI) reduction and organic chemical oxidation by TiO2 photocatalysis.  

PubMed

Here we report the simultaneous Cr(VI) reduction and 4-chlorophenol (4-CP) oxidation in water under visible light (wavelength > 400 nm) using commercial Degussa P25 TiO2. This remarkable observation was attributed to a synergistic effect among TiO2, Cr(VI), and 4-CP. It is well known that TiO2 alone cannot remove either 4-CP or Cr(VI) efficiently under visible light. Moreover, the interaction between Cr(VI) and 4-CP is minimal if not negligible. However, we found that the combination of TiO2, Cr(VI), and 4-CP together can enable efficient Cr(VI) reduction and 4-CP oxidation under visible light. The specific roles of the three ingredients in the synergistic system were studied parametrically. It was found that optimal concentrations of Cr(VI) and TiO2 exist for the Cr(VI) reduction and 4-CP oxidation. Cr(VI) was compared experimentally with other metals such as Cu(ll), Fe(lll), Mn(IV), Ce(IV), and V(V). Among all these metal ions, only Cr(VI) promotes the photocatalytic oxidation of 4-CP. The amount of 4-CP removed was directly related to the initial concentration of Cr(VI). The system was also tested with four other chemicals (aniline, salicylic acid, formic acid, and diethyl phosphoramidate). We found that the same phenomenon occurred for organics containing acid and/or phenolic groups. Cr(VI) was reduced at the same time as the organic chemicals being oxidized during photoreaction under visible light. The synergistic effect was also found with pure anatase TiO2 and rutile TiO2. This study demonstrates a possible economical way for environmental cleanup under visible light. PMID:16173589

Sun, Bo; Reddy, Ettireddy P; Smirniotis, Panagiotis G

2005-08-15

189

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

190

Photocatalytic degradation of pesticides in pure water and a commercial agricultural solution on TiO2 coated media.  

PubMed

Heterogeneous photocatalysis of pesticides is an effective process for removing pesticides from pure water. With a view to treating real agricultural effluents, this paper deals with the degradation of the chlortoluron and cyproconazole pesticides in pure water and the treatment of commercial solutions by photocatalysis on TiO2 coated media. The process was effective in degrading and mineralizing the pesticides. The changes of the fate of heteroatoms showed that during irradiation of the chlortoluron and cyproconazole, NH4+ and NO3(-) ions were produced. A release of chloride ions was observed from the beginning of the irradiation and stoichiometry was achieved. The photodegradation of chlortoluton and cyproconazole in commercial solutions was studied. For the degradation of chlortoluton in a commercial solution, the mineralization was completely achieved whereas in the case of the commercial cyproconazole solution, the degradation kinetic was lower. These results highlight the fact that the chemical nature of the additives in the commercial pesticide solutions does significantly affect the degradation yield of the target compound by photocatalysis. PMID:17709129

Lhomme, L; Brosillon, S; Wolbert, D

2007-08-20

191

Modification of indium tin oxide electrodes with nucleic acids: detection of attomole quantities of immobilized DNA by electrocatalysis  

PubMed

Indium tin oxide electrodes were modified with DNA, and the guanines in the immobilized nucleic acid were used as a substrate for electrocatalytic oxidation by Ru(bpy)3(3+) (bpy = 2,2'-bipyridine). Nucleic acids were deposited onto 12.6-mm2 electrodes from 9:1 DMF/water mixtures buffered with sodium acetate. The DNA appeared to denature in the presence of DMF, leading to adsorption of single-stranded DNA. The nucleic acid was not removed by vigorous washing or heating the electrodes in water, although incubation in phosphate buffer overnight liberated the adsorbed biomolecule. Acquisition of cyclic voltammograms or chronoamperomograms of Ru(bpy)3(2+) at the modified electrodes produced catalytic signals indicative of oxidation of the immobilized guanine by Ru(III). The electrocatalytic current was a linear function of the extent of modification with a slope of 0.5 microA/pmol of adsorbed guanine; integration of the current-time traces gave 2.2+/-0.4 electrons/guanine molecule. Use of long DNA strands therefore gave steep responses in terms of the quantity of adsorbed DNA strand. For example, electrodes modified with a 1497-bp PCR product from the HER-2 gene produced detectable catalytic currents when as little as 550 amol of strand was adsorbed, giving a sensitivity of 44 amol/mm2. PMID:10959961

Armistead; Thorp

2000-08-15

192

Absorption and electrochemical properties of cobalt and iron phthalocyanines and their quaternized derivatives: aggregation equilibrium and oxygen reduction electrocatalysis.  

PubMed

The synthesis and investigation of the electronic properties of Co(II) and Fe(II)tetrakis(pyridine-3-yloxy)phthalocyanines, as well as the respective quaternized complexes, are reported here. After quaternization reaction, the compounds showed increased solubility in water, and their aggregation equilibrium was analyzed by varying the solution concentration, pH, and composition. Cyclic voltammograms of the four compounds showed both metal and ring centered redox processes, with the former being highly sensitive to methylation of the pyridyl groups. The catalytic effect of the phthalocyanines adsorbed on glassy carbon electrodes in the oxygen reduction reaction (ORR) was investigated by cyclic voltammetry (CV) and rotating disk voltammetry (RDV). The highest catalytic activities were observed for the Fe(II) complexes in alkaline media, and a 2 + 2 mechanism, which consists of a first complete O2 to H2O2 process and a subsequent incomplete H2O2 to H2O process, is proposed. PMID:23914935

Tasso, Thiago Teixeira; Furuyama, Taniyuki; Kobayashi, Nagao

2013-08-05

193

Hydrogen electrocatalysis: A basic solution  

NASA Astrophysics Data System (ADS)

Hydrogen-oxygen alkaline fuel cells are promising devices for the 'hydrogen economy' but their oxidation of hydrogen fuel is slow compared with that of acidic fuel cells. More efficient electrocatalysts have now been prepared in which the adsorption of hydroxyl groups onto the electrode surface is controlled through suitable promoters.

Koper, Marc T. M.

2013-04-01

194

Effect of nitrogen doping on the microstructure and visible light photocatalysis of titanate nanotubes by a facile cohydrothermal synthesis via urea treatment  

NASA Astrophysics Data System (ADS)

A facile one-step cohydrothermal synthesis via urea treatment has been adopted to prepare a series of nitrogen-doped titanate nanotubes with highly efficient visible light photocatalysis of rhodamine B, in an effect to identify the effect of nitrogen doping on the photodegradation efficiency. The morphology and microstructure of the thus-prepared N-doped titanates were characterized by nitrogen adsorption/desorption isotherms, transmission electron microscopy, and scanning electron microscopy. With increasing urea loadings, the N-doped titanates change from a porous multi-layer and nanotube-shaped to a dense and aggregated particle-shaped structure, accompanied with reduced specific surface area and pore volume and enhanced pore diameter. Interstitial linkage to titanate via TiON and TiNO is confirmed by X-ray photoelectron spectroscopy. Factors governing the photocatalytic degradation such as the specific surface area of the catalyst and the degradation pathway are analyzed, a mechanistic illustration on the photodegradation is provided, and a 3-stage degradation mechanism is identified. The synergistic contribution due to the enhanced deethylation and chromophore cleavage on rhodamine B molecules and the reduced band gap on the catalyst TiO2 by interstitial nitrogen-doping has been accounted for the high photodegradation efficiency of the N-doped titanate nanotubes.

Hu, Cheng-Ching; Hsu, Tzu-Chien; Lu, Shan-Yu

2013-09-01

195

Model reactor for photocatalytic degradation of persistent chemicals in ponds and waste water.  

PubMed

A laboratory scale flow-through model reactor for the degradation of persistent chemicals using titanium dioxide (TiO2) as photocatalyst immobilized on glass beads is presented. In the test system with a volume of 18 L contaminated water is pumped to the upper part of the floating reactor and flows over the coated beads which are exposed to UV-radiation. The degradation of two dyes of different persistence was investigated. Primary degradation of methylene blue did not fit a first order kinetic due to coincident adsorption onto the photocatalyst and direct photolysis, resulting in a half-life of 6 h. A filtrate of a green algae suspension accelerated the colour removal. In contrast, reactive red 2 was degraded only by photocatalysis; neither adsorption nor direct photolysis led to a colour removal. The course of primary degradation followed a first order kinetic with a half-life of 18 h and a rate constant of 0.04 h-1. Analysis of the degradation products indicated mineralization by detection of NO2- and NO3-, accompanied by a decrease of pH and an increase of conductivity. A successful adaptation of the model reactor (scale 1:10) to dimensions required for surface waters and waste water treatment plants would be a cost-efficient and environmentally sustainable application of photocatalysis for the treatment of industrially polluted water and could be of relevance for third world countries, particularly those favoured by high solar radiation. PMID:10633546

Franke, R; Franke, C

1999-12-01

196

Solvothermal synthesis of N-doped TiO2 nanotubes for visible-light-responsive photocatalysis.  

PubMed

Visible-light-responsive tubular N-doped TiO2 nanocrystallites were synthesized via an environment-conscious solvothermal treatment of protonated titanate nanotubes in an NH4Cl/ethanol/water solution. PMID:19048159

Jiang, Zheng; Yang, Fan; Luo, Nianjun; Chu, Bryan T T; Sun, Deyin; Shi, Huahong; Xiao, Tiancun; Edwards, Peter P

2008-11-04

197

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

198

Rapid anodic formation of high aspect ratio WO3 layers with self-ordered nanochannel geometry and use in photocatalysis.  

PubMed

Channel hopping: the formation of WO(3) layers with an aligned nanochannel morphology by using self-organizing anodization of a tungsten metal substrate is demonstrated. The nanochannel layers with diameters of approximately 9 nm can be grown to about 10 ?m thickness. Layers optimized for length and structure are promising for visible-light photocatalytic applications, such as water-splitting photoanodes. PMID:23042381

Wei, Wei; Shaw, Santosh; Lee, Kiyoung; Schmuki, Patrik

2012-10-05

199

Rapid anodic formation of high aspect ratio WO 3 layers with self-ordered nanochannel geometry and use in photocatalysis  

Microsoft Academic Search

Channel hopping: The formation of WO 3 layers with an aligned nanochannel morphology by using self-organizing anodization of a tungsten metal substrate is demonstrated. The nanochannel layers with diameters of approximately 9 nm can be grown to about 10 ?m thickness. Layers optimized for length and structure are promising for visible-light photocatalytic applications, such as water-splitting photoanodes (see figure). Copyright

W. Wei; S. Shaw; K. Lee; P. Schmuki

2012-01-01

200

A two-step photoexcitation system for photocatalytic water splitting into hydrogen and oxygen under visible light irradiation  

NASA Astrophysics Data System (ADS)

The developments of water-splitting systems that can efficiently use visible light have been a major challenge for many years in order to realize efficient conversion of solar light. We have developed a new type of photocatalysis system that can split water into H2 and O2 under visible light irradiation, which was inspired by the two-step photoexcitation (Zscheme) mechanism of natural photosynthesis in green plants. In this system, the water splitting reaction is broken up into two stages: one for H2 evolution and the other for O2 evolution; these are combined by using a shuttle redox couple (Red/Ox) in the solution. The introduction of a Z-scheme mechanism reduces the energy required to drive each photocatalysis process, extending the usable wavelengths significantly (~460 nm for H2 evolution and ~600 nm for O2evolution) from that in conventional water splitting systems (~460 nm) based on one-step photoexcitation in single semiconductor material.

Abe, Ryu

2011-09-01

201

Surface effect on electronic and optical properties of Bi2Ti2O7 nanowires for visible light photocatalysis  

NASA Astrophysics Data System (ADS)

We theoretically performed the structural, electronic, and optical properties of the pyrochlore Bi2Ti2O7 nanowires for photocatalytic applications using pseudopotential density-functional theory calculations. The groundwork of electronic structure calculations showed a possible band gap modification of the Bi2Ti2O7 nanowires compared to that of the bulk. The midband states induced by the oxygen atoms and bismuth atoms on the surface of nanowires leads to a shift in the valence band toward the conduction band, which enables reduction of the band gap. The calculated optical results indicated that the absorption edges shift of nanowires towards the red-light region. These theoretical results suggested that the pyrochlore Bi2Ti2O7 nanowires can be expected to be a promising candidate for photocatalytic applications such as solar-assisted water splitting reactions.

Fu, Q.; He, T.; Li, J. L.; Yang, G. W.

2012-06-01

202

Treatment of emerging contaminants in wastewater treatment plants (WWTP) effluents by solar photocatalysis using low TiO2 concentrations.  

PubMed

The optimal photocatalyst concentration for industrial wastewater treatment in current photoreactor designs is several hundreds of milligrams per liter. However, the elimination of emerging contaminants (ECs), which are present at extremely low concentrations in waste water treatment plants (WWTP) effluents might be accomplished at much lower catalyst (TiO(2)) concentrations. One of the main drawbacks of reducing catalyst loading below the optimum is the loss of useful photons which instead are transmitted through the TiO(2) suspension without being absorbed by the catalyst. Accordingly, in this work, laboratory and solar pilot-scale experiments were performed with real WWTP effluents to evaluate the kinetics of photocatalytic degradation of 52 emerging contaminants under realistic (ppb) concentrations. The analysis of the samples was accomplished by solid phase extraction (SPE) followed by liquid chromatography-mass spectrometry (LC-MS). In view of the results, low concentrations of TiO(2) of the order of tens of milligrams per liter were found to be insufficient for the degradation of the ECs in photoreactors with a short light-path length (29 cm). However, it was established that solar reactors of diameters of several hundreds of millimetres could be used for the efficient removal of ECs from WWTP effluents. The results presented show a general methodology for selecting the most efficient reactor diameter on the basis of the desired catalyst concentration. PMID:21943922

Prieto-Rodriguez, L; Miralles-Cuevas, S; Oller, I; Agüera, A; Li Puma, G; Malato, S

2011-09-12

203

The design, synthesis and fabrication of electrospun titanium dioxide nanomaterials for use in greener chemical transformations and photocatalysis  

NASA Astrophysics Data System (ADS)

Electrospun TiO2 nanofibers present a unique class of active materials with optimized photoactivity and cost efficiency due to ease of synthesis and fabrication in bulk. The high aspect ratios for these nanostructured materials shorten the transportation length of electrons and holes from the crystal interface to the surface, thus accelerating their migration to the surface active sites. Additionally, the increased surface areas and high porosity ensures maximum adsorption of the reaction intermediates on the TiO2 surface, and high diffusion co-efficient within the material. The primary goal of this dissertation is to develop TiO2 nanofibers as an efficient and cost-effective catalyst for practical and multi-purpose application in greener chemical transformations and environmental remediation from organic pollutants in waste-waters. To achieve this, the surface, crystal and electronic structures of electrospun TiO2 will be optimized to allow for visible light-enhanced photodegradation processes. Pd nanoparticles of between 2-5 nm were successfully stabilized on the surface of electrospun nanofibers which had diameters between 150 ± 50 nm. The new catalyst was found to have increased surface area and improved catalytic functions compared to commercially available materials or other Pd-TiO2 catalysts produced by different modes of synthesis. The activity and selectivity of 0.05 mol% Pd-TiO2 catalyst in the Heck reaction has been investigated with a careful look into the nature of starting materials and products under varying conditions of temperature, solvent and base. The catalyst was found to be highly active under air atmosphere with reaction temperatures of up to 160°C. Optimized reaction conditions resulted in a 98% yield of trans-stilbene for the iodobenzene-styrene system with a TOF value of 7.85 min-1. The surface properties of TiO2 nanofibers were explored for the in-situ and ex-situ nucleation and growth of group VIII metal nanoparticles. The nanoparticles were effectively anchored on the numerous pores on the TiO2 surface that acted as seeding grounds for the control of nanoparticle growth. The semiconductor nature of these TiO2-based catalysts enabled UV/visible light enhanced generation of reactive O2 species for the degradation of rhodamine B. The photodegradation followed first order kinetics with a rate constant of 0.0158 min-1.

Obuya, Emilly Akinyi

204

Development of solar-driven electrochemical and photocatalytic water treatment system using a boron-doped diamond electrode and TiO2 photocatalyst.  

PubMed

A high-performance, environmentally friendly water treatment system was developed. The system consists mainly of an electrochemical and a photocatalytic oxidation unit, with a boron-doped diamond (BDD) electrode and TiO(2) photocatalyst, respectively. All electric power for the mechanical systems and the electrolysis was able to be provided by photovoltaic cells. Thus, this system is totally driven by solar energy. The treatment ability of the electrolysis and photocatalysis units was investigated by phenol degradation kinetics. An observed rate constant of 5.1 x 10(-3)dm(3)cm(-2)h(-1) was calculated by pseudo-first-order kinetic analysis for the electrolysis, and a Langmuir-Hinshelwood rate constant of 5.6 microM(-1)min(-1) was calculated by kinetic analysis of the photocatalysis. According to previous reports, these values are sufficient for the mineralization of phenol. In a treatment test of river water samples, large amounts of chemical and biological contaminants were totally wet-incinerated by the system. This system could provide 12L/day of drinking water from the Tama River using only solar energy. Therefore, this system may be useful for supplying drinking water during a disaster. PMID:19863989

Ochiai, Tsuyoshi; Nakata, Kazuya; Murakami, Taketoshi; Fujishima, Akira; Yao, Yanyan; Tryk, Donald A; Kubota, Yoshinobu

2009-10-01

205

Photocatalysis on TiO{sub 2} surfaces investigated by atomic force microscopy: Photodegradation of partial and full monolayers of stearic acid on TiO{sub 2}(110)  

SciTech Connect

The photocatalytic properties of TiO{sub 2} are of practical significance in applications ranging from solar energy conversion through environmental remediation to antibacterial, self-cleaning, and antifogging functions. The authors have studied the nature and surface morphological changes associated with the photodegradation of stearic acid LB films on TiO{sub 2}(110). Interestingly, submonolayers of stearic acid consisted of circular domains of various sizes--a feature very attractive for monitoring TiO{sub 2} photocatalysis by AFM. The authors noted that there was no bulk differential reactivity at island edges compared to the interior. This suggests that the rate of photodegradation of the stearic acid molecules is independent of their location in the island. Accordingly, the overall surface reactivity trends were similar for both partial films and complete films. Likewise, the observed inhomogeneous reactivity patterns appear to be a reflection of the transient distribution of the reaction centers.

Sawunyama, P. [Kanagawa Academy of Science and Technology, Atsugi, Kanagawa (Japan). Dept. of Applied Chemistry; Fujishima, Akira; Hashimoto, Kazuhito [Kanagawa Academy of Science and Technology, Atsugi, Kanagawa (Japan). Dept. of Applied Chemistry]|[Univ. of Tokyo (Japan)

1999-05-11

206

Photodegradation of haloacetic acids in water.  

PubMed

The global distribution and high stability of some haloacetic acids (HAAs) has prompted concern that they will tend to accumulate in surface waters and pose threats to humans and the ecosystem. It is important to study the degradation pathways of HAAs in aqueous systems to understand their ecotoxicological effects. Previous studies involving thermal degradation reactions show relatively long lifetimes for HAAs in the natural environment. Photolysis and photocatalytic dissociation are potentially efficient routes for the degradation of HAAs such as trichloroacetic acid to hydrochloric acid, carbon dioxide and chloroform, although such processes are poorly understood in surface waters. In our present study, we have used light to degrade the HAAs in the presence of titanium dioxide suspensions. All chloro and bromo HAAs degrade in photocatalysis experiments and the rate of degradation is directly proportional to the number of halogen atoms in the acid molecule. The half-lives of the HAAs from the photodegradation at 15 degrees C in the presence of suspended titanium dioxide photocatalyst are 8, 14, 83 days for the tri-, di- and mono-bromoacetic acids. Tri-, di- and mono-chloroacectic acids have half-lives of 6, 10 and 42 days respectively. The mixed bromochloro and chlorodifluoroacetic acids degrade with half-lives of 18 and 42 days respectively. Our results therefore suggest that the photocatalytic process can provide an additional degradation pathway for the HAAs in natural waters. PMID:14987945

Lifongo, Lydia L; Bowden, Derek J; Brimblecombe, Peter

2004-04-01

207

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

2011-05-31

208

Separation of titanium dioxide from photocatalytically treated water by cross-flow microfiltration.  

PubMed

This study focuses on the separation of titanium dioxide from water by cross-flow microfiltration (CMF) within wastewater treatment by photocatalysis using slurry reactor systems. The systematic studies have shown that the separation performance of TiO2 particles is strongly affected by cross-flow velocity, transmembrane pressure, feed concentration, pH of the suspension and ionic strength. An extreme sensitivity to pH and electrolyte concentration indicates the importance of interfacial effects in solid-liquid separation of TiO2 particles. Under optimal conditions, permeate fluxes of up to 1250 l m-2 h-1, approaching those of pure water, could be obtained with a polypropylene membrane which is not sensitive to abrasion. The obtained results makes TiO2 separation by cross-flow microfiltration attractive in solar-catalytic detoxification. PMID:11268846

Xi, W; Geissen, S U

2001-04-01

209

Fabrication of bulk-modified carbon paste electrode containing alpha-PW12O40(3-) polyanion supported on modified silica gel: Preparation, electrochemistry and electrocatalysis.  

PubMed

Alpha-PW(12)O(40)(3-) (PW(12)) supported on the surface of silica gel derivatized by 3-aminopropyl(triethoxy)silane (devoted briefly as SiNH(3)PW(12)) was synthesized and used as bulk modifier to fabricate a renewable three-dimensional chemically modified electrode. The electrochemical behavior of the modified electrode was characterized by cyclic voltammetry. There is an ionic bonding character between PW(12) and the surface amino groups of modified silica, which greatly improves the stability of SiNH(3)PW(12)-modified carbon paste electrode due to insolubility of silica gel in water. The SiNH(3)PW(12) bulk-modified carbon paste electrode not only maintains the electrochemical activity of PW(12), but also exhibits remarkable advantages of renewability, as well as simple preparation and inexpensive material. The modified electrode offers an excellent and stable electrocatalytic response for the reduction of IO(3)(-) and hydrogen peroxide. The SiNH(3)PW(12)-CPE is successfully applied as an electrochemical detector to monitor IO(3)(-) in flow injection analysis (FIA). The catalytic peak current was found to be linear with the IO(3)(-) concentration in the range 5x10(-6) to 1x10(-3)molL(-1). The detection limit of the proposed method was found to be 3.1x10(-6)molL(-1) for IO(3)(-) determination. PMID:18371727

Hamidi, Hassan; Shams, Esmaeil; Yadollahi, Bahram; Esfahani, Farhad Kabiri

2007-08-02

210

Perovskite Oxides: Oxygen Electrocatalysis and Bulk Structure.  

National Technical Information Service (NTIS)

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...

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

1987-01-01

211

Functionalization and electrocatalysis on carbon nanofibers  

NASA Astrophysics Data System (ADS)

Nanoscale hybrid materials such as metal nanoparticles dispersed on nanostructured carbons are promising for use as electrocatalysts due to their chemical and physical properties. Vertically aligned carbon nanofibers (VACNFs) have a unique structure that exposes large amounts of graphitic edge-plane along the sidewalls, suggesting that hybrid VACNF-nanoparticle structures may have particularly good electrochemical response for electrocatalytic reactions. As with other carbon materials, the surface of VACNFs is not highly selective, but the high reactivity of the graphitic edge-plane sites allows for chemical modification with functional organic monolayers, avoiding the need for harsh oxidation techniques. The use of molecular functionalization to interface VACNFs with catalytic metal particles was investigated using two different growth techniques: electroless deposition and pulsed electrochemical deposition. Deposited particles are demonstrated to be catalytically active, despite the presence of the molecular layer. The presence of graphitic edge-plane is found to be important for electrochemical nucleation. Evaluation of the catalytic behavior of this hybrid system using the methanol oxidation reaction as a model system reveals differences in initial catalytic activity and long-term stability of nanoparticles produced by the two growth methods. Development of the electrochemical deposition method demonstrates that nucleation and growth can be controlled by the use of multiple-pulse sequences. This work provides insights into the use of molecular systems for chemical selectivity and the importance of edge-plane sites in catalytic activity of carbon-based hybrid nanostructures.

Hogendoorn, Stephanie Ruth

212

Fabrication of CaFe2O4\\/MgFe2O4 bulk heterojunction for enhanced visible light photocatalysis  

Microsoft Academic Search

A bulk heterojunction photocatalyst of interfacing CaFe2O4 and MgFe2O4 nanoparticles is highly active for oxidative degradation of isopropyl alcohol and hydrogen production from water under visible light, because the exciton easily reaches the interface and dissociates to minimize recombination.

Hyun Gyu Kim; Pramod H. Borse; Jum Suk Jang; Euh Duck Jeong; Ok-Sang Jung; Yong Jae Suh; Jae Sung Lee

2009-01-01

213

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

214

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

215

Water, Water Everywhere  

NSDL National Science Digital Library

In this activity, learners estimate how much water they think can be found in various locations on the Earth in all its states (solid, liquid, and gas) to discover the different water ratios in the Earth's total water supply. Learners divide 1000 ml of water (representing the total amount of water on Earth) amongst eight beakers as they predict the various ratios. Then learners measure the amounts of water that reflect the actual ratios and compare their predictions to reality. Learners will be surprised to find out that most of Earth's water is found in the ocean. This resource also includes information about flash floods and flood safety.

Service, National W.

2012-06-26

216

Water 2: Disappearing Water  

NSDL National Science Digital Library

In this lesson, students will observe the amount of water in an open container vs a closed container over time. This lesson is the second 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. In this second lesson, students will focus on the concept that water can go back and forth from one form to another and the amount of water will remain the same.

217

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

218

Healthy Water  

MedlinePLUS

... Water Systems, Water Fluoridation, Camping, Hiking, Travel… Global Water, Sanitation, & Hygiene (WASH) Community Systems, Household Treatment & Storage, Sanitation and Hygiene, Travelers’ Health… Water-related Emergencies & ...

219

The detrimental influence of bacteria (E. coli, Shigella and Salmonella) on the degradation of organic compounds (and vice versa) in TiO(2) photocatalysis and near-neutral photo-Fenton processes under simulated solar light.  

PubMed

TiO(2) photocatalytic and near-neutral photo-Fenton processes were tested under simulated solar light to degrade two models of natural organic matter - resorcinol (R) (which should interact strongly with TiO(2) surfaces) and hydroquinone (H) - separately or in the presence of bacteria. Under similar oxidative conditions, inactivation of Escherichia coli, Shigella sonnei and Salmonella typhimurium was carried out in the absence and in the presence of 10 mg L(-1) of R and H. The 100% abatement of R and H by using a TiO(2) photocatalytic process in the absence of bacteria was observed in 90 min for R and in 120 min for H, while in the presence of microorganisms abatement was only of 55% and 35% for R and H, respectively. Photo-Fenton reagent at pH 5.0 completely removed R and H in 40 min, whereas in the presence of microorganisms their degradation was of 60% to 80%. On the other hand, 2 h of TiO(2) photocatalytic process inactivated S. typhimurium and E. coli cells in three and six orders of magnitude, respectively, while S. sonnei was completely inactivated in 10 min. In the presence of R or H, the bacterial inactivation via TiO(2) photocatalysis was significantly decreased. With photo-Fenton reagent at pH 5 all the microorganisms tested were completely inactivated in 40 min of simulated solar light irradiation in the absence of organics. When R and H were present, bacterial photo-Fenton inactivation was less affected. The obtained results suggest that in both TiO(2) and iron photo-assisted processes, there is competition between organic substances and bacteria simultaneously present for generated reactive oxygen species (ROS). This competition is most important in heterogeneous systems, mainly when there are strong organic-TiO(2) surface interactions, as in the resorcinol case, suggesting that bacteria-TiO(2) interactions could play a key role in photocatalytic cell inactivation processes. PMID:22370626

Moncayo-Lasso, Alejandro; Mora-Arismendi, Luis Enrique; Rengifo-Herrera, Julián Andrés; Sanabria, Janeth; Benítez, Norberto; Pulgarin, César

2012-02-28

220

Photoelectrocatalytic disinfection of water and wastewater: performance evaluation by qPCR and culture techniques.  

PubMed

Photoelectrocatalytic oxidation (PEC) was evaluated as a disinfection technique using water and secondary treated wastewater spiked with Escherichia coli and Enterococcus faecalis. PEC experiments were carried out using a TiO(2)/Ti-film anode and a zirconium cathode under simulated solar radiation. Bacterial inactivation was monitored by culture and quantitative polymerase chain reaction (qPCR). Inactivation rates were enhanced when the duration of the treatment was prolonged and when the bacterial density and the complexity of the water matrix were decreased. E. coli cells were reduced by approximately 6 orders of magnitude after 15 min of PEC treatment in water at 2V of applied potential and an initial concentration of 10(7) CFU/mL; pure photocatalysis (PC) led to about 5 log reduction, while electrochemical oxidation alone resulted in negligible inactivation. The superiority of PEC relative to PC can be attributed to a more efficient separation of the photogenerated charge carriers. Regarding disinfection in mixed bacterial suspensions, E. coli was more susceptible than E. faecalis at a potential of 2V. The complex composition of wastewater affected disinfection efficiency, yielding lower inactivation rates compared to water treatment. qPCR yielded lower inactivation rates at longer treatment times than culture techniques, presumably due to the fact that the latter do not take into account the viable but not culturable state of microorganisms. PMID:23428546

Venieri, Danae; Chatzisymeon, Efthalia; Politi, Eleonora; Sofianos, Spiridon S; Katsaounis, Alexandros; Mantzavinos, Dionissios

2013-03-01

221

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

2011-07-29

222

Summary of engineering-scale experiments for the Solar Detoxification of Water project  

SciTech Connect

This report contains a summary of large-scale experiments conducted at Sandia National Laboratories under the Solar Detoxification of Water project. The objectives of the work performed were to determine the potential of using solar radiation to destroy organic contaminants in water by photocatalysis and to develop the process and improve its performance. For these experiments, we used parabolic troughs to focus sunlight onto glass pipes mounted at the trough`s focus. Water spiked with a contaminant and containing suspended titanium dioxide catalyst was pumped through the illuminated glass pipe, activating the catalyst with the ultraviolet portion of the solar spectrum. The activated catalyst creates oxidizers that attack and destroy the organics. Included in this report are a summary and discussion of the implications of experiments conducted to determine: the effect of process kinetics on the destruction of chlorinated solvents (such trichloroethylene, perchloroethylene, trichloroethane, methylene chloride, chloroform and carbon tetrachloride), the enhancement due to added hydrogen peroxide, the optimal catalyst loading, the effect of light intensity, the inhibition due to bicarbonates, and catalyst issues.

Pacheco, J.E.; Yellowhorse, L.

1992-03-01

223

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

2012-09-18

224

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

225

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

226

TiO2Based Heterogeneous Photocatalytic Water Treatment Combined with Ozonation  

Microsoft Academic Search

The degradations of aliphatic carboxylic acids (formic acid, acetic acid, and propionic acid) were investigated by a combination of TiO2-based photocatalysis and ozonation at pH = 2. The carboxylic acids were analyzed by high-performance liquid chromatography (HPLC), while the mineralization process was characterized by measuring the dissolved organic carbon (DOC) content. The efficiency of heterogeneous photocatalysis combined with ozonation was

István Ilisz; Attila Bokros; András Dombi

2004-01-01

227

Catalyst deactivation in gas-solid photocatalysis  

SciTech Connect

Photocatalyst lifetime is potentially important in process economics, as it sets maximum run times between catalyst regeneration or replacement. This note surveys the literature of photocatalytic air treatment and purification in order to identify the emerging photocatalyst deactivation issue. For each pertinent paper, the authors evaluate the total number of molecules converted by a photocatalyst over time and compare this cumulative photocatalytic molecular conversion to the estimated total number of illuminated surface sites. This comparison establishes that photocatalyst deactivation is virtually always found in single-pass fixed-bed photoreactors for cumulative contaminant conversion in excess of 1-10 equivalent monolayers. 28 refs., 1 fig., 1 tab.

Sauer, M.L.; Ollis, D.F. [North Carolina State Univ., Raleigh, NC (United States)

1996-09-15

228

Photocatalysis with Large-Scale Trough Collectors.  

National Technical Information Service (NTIS)

Sandia National Laboratories' part in the Department of Energy's Solar Detoxification of Hazardous Waste Initiative is focused on conducting large-scale solar photocatalytic experiments. Sandia's efforts support fundamental laboratory research performed b...

J. E. Pacheco

1991-01-01

229

Treatment of Organic Pollutants by Heterogeneous Photocatalysis  

NASA Astrophysics Data System (ADS)

An experimental investigation was carried out in the area of heterogeneous catalysis using TiO2 as a catalyst for the removal of the model organic compounds (benzoic acid and phenol) in three different photocatalytic reactors. Natural and artificial UV source of radiation were used and the performance of the reactors were studied in the present investigation. The extent of degradation/removal of the organic compounds was found by varying the initial concentration, flow rate, pipe diameter, TiO2 concentration and exposure time.

Feroz, S.; Jesil, A.

2012-08-01

230

Attenuation of methyl tert-butyl ether in water using sunlight and a photocatalyst.  

PubMed

The use of methyl tert-butyl ether (MTBE) as a gasoline additive has resulted in increasing pollution of groundwater. Most of the conventional treatment technologies are inefficient or costly when the initial concentration of MTBE is low (< 200 microg/L). To find an ecology friendly and inexpensive method for MTBE remediation, we used solar radiation with titanium dioxide (TiO2) as a photocatalyst. For synthetic samples, almost complete degradation (99+%) of MTBE was observed at the end of 5-hour test run with 0.05 g/L of slurry TiO2. Intermediate products detected were tertiary butyl formate, tertiary butyl alcohol, and trace amounts of acetone. Studies conducted using contaminated groundwater samples with TiO2 and sunlight showed that aromatic organic species benzene, toluene, ethylbenzene, and xylenes (BTEX) were degraded up to a factor of 10 times faster than MTBE. However, dissolved metals (Fe2+) and chloride ions in contaminated waters decreased the photo-activity of TiO2 for the degradation of MTBE. Reducing the pH of the groundwater samples increased the MTBE degradation rate threefold. Photocatalysis accelerates the solar degradation of MTBE and reduces its half-life by more than 3 orders of magnitude. The study indicated that solar degradation is a low-cost and effective alternative to attenuate MTBE in drinking water supplies. PMID:12043968

Sahle-Demessie, E; Enriquez, J; Gupta, G

231

Potable water from waste water  

Microsoft Academic Search

The idea of obtaining potable water from waste water is a psychologically difficult one for many people to accept. The tendency is to think that waste water is dirty and cannot be converted to clean water. This book describes significant advances in waste water treatment technology which make possible the control and\\/or removal of conventional pollutants, thus making potable water

Gillies

1981-01-01

232

Special Topics in Water Science (Water Pollution)  

MedlinePLUS

... Basics Water Properties Water Cycle Surface Water Groundwater Water Quality Water Use Activities Photos Q&A Teachers Contact ... explore other water-science topic areas, such as water quality, urbanization and water, saline water, watersheds, runoff, and ...

233

Water Phases  

NSDL National Science Digital Library

Every day, we encounter water in its three different forms: liquid water, solid ice, and water vapor, an invisible gas. Most other substances can exist in these three phases as well, but water is unique because it is the only substance that can exist in all three phases at Earth's temperature. This collection of still images produced for Teachers' Domain depicts water in each of its three phases: liquid water, solid ice, and water vapor.

Foundation, Wgbh E.

2009-07-21

234

Water Crisis  

Microsoft Academic Search

Water crisis was not considered seriously at the Dublin and Rio conferences. It was put on the world agenda primarily by the Stockholm Water Symposia. Water management is likely to change more during the next twenty years compared to the past 2,000 years. The paper reviews the global water situtation based on the latest data available. In terms of water

Asit K. Biswas

1999-01-01

235

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.

236

Anomalous Water.  

National Technical Information Service (NTIS)

Of the many anomalies reported for water, the study concentrated on those anomalous properties exhibited by three types of material--the bound water in animate nature, the interfacially or structurally ordered water in inanimate nature, and the anomalous ...

B. D. Allan R. L. Norman

1970-01-01

237

Drinking Water  

MedlinePLUS

... safest water supplies in the world, but drinking water quality can vary from place to place. It depends on the condition of the source water and the treatment it receives. Treatment may include ...

238

A practical demonstration of water disinfection using TiO2 films and sunlight.  

PubMed

The scope of this study is the assessment of the efficiency of solar disinfection by heterogeneous photocatalysis with sol-gel immobilized (titanium dioxide) TiO2 films over glass cylinders. The solar disinfection process known as SODIS was considered as a reference. Spring water naturally polluted with coliform bacteria was exposed to sunlight in plastic bottles with and without TiO2 over simple solar collectors and the disinfection effectiveness was measured. Total and fecal coliforms quantification was performed by means of the chromogenic substrate method in order to obtain the efficiency of each disinfection treatment. The disinfection with TiO2 was more efficient than the SODIS process, inactivating total coliforms as well as fecal coliforms. On a sunny day (more than 1000 W m(-2) irradiance), it took the disinfection with immobilized TiO2 15 min of irradiation to inactivate the fecal coliforms to make them undetectable. For inactivation of total coliforms, 30 min was required, so that in less than half the time it takes SODIS, the treated water complies with the microbial standards for drinking water in Mexico. Another important part of this study has been to determine the bacterial regrowth in water after the disinfection processes were tested. After SODIS, bacterial regrowth of coliforms was observed. In contrast, when using the TiO2 catalyst, coliforms regrowth was not detected, neither for total nor for fecal coliforms. The disinfection process using TiO2 kept treated water free of coliforms at least for seven days after sun irradiation. This demonstration opens the possibility of application of this simple method in rural areas of developing countries. PMID:16949121

Gelover, Silvia; Gómez, Luis A; Reyes, Karina; Teresa Leal, Ma

2006-09-01

239

Water resources  

Microsoft Academic Search

Describes aspects of water resource systems and the human agencies that affect them. Defines the basics of successful resource management, addresses problems that confront water resource managers, and identifies a range of solutions for more efficient and equitable resource control and use. Covers quality of water supply, flood control, hydroelectric power, national and regional water authorities, and international aspects, with

A. McDonald; D. Kay

1989-01-01

240

Microbiology: water  

Microsoft Academic Search

Topics discussed in this literature review with 173 references dealing with the microbiology of aquatic ecosystems include microbial indicators of water pollution, and the microbial ecology of water. Solar radiation and naturally occurring microbial predators are important forces in the natural self-purification of polluted surface waters. The relationship between water quality and microbiology of river systems and natural lakes is

Geldrich

1982-01-01

241

Surface Water  

NSDL National Science Digital Library

Surface Water: This is the USGS Water Science for School's page and the topic is surface water. Explained are surface water use, importance, rivers and streams. Also answers the questions of what is runoff, how is the flow of a stream measured, how does stream height relate to flow and much, much more.

2008-06-05

242

Disappearing Water  

NSDL National Science Digital Library

In this outdoor water activity, learners explore evaporation by painting with water and tracing puddles. Learners will discover that wet things become dry as the water evaporates. This activity is part of the curriculum Explore Water, related to Peep and the Big Wide World, a preschool science series on public television. The activity starts on page 36 of the PDF.

Foundation, Wgbh E.

2005-01-01

243

Water Cycle  

NSDL National Science Digital Library

4th Grade Science - Water Cycle Water Cycle two day interactive lesson plan. DAY 1: Welcome to the Water Cycle! Today we are going to be exploring and finding out more about the wonderful Water Cycle! For starters we are going to start with a movie, click the following link and watch the video and ...

Staley, Mrs.

2009-11-09

244

On the similarity and dissimilarity between photocatalytic water splitting and photocatalytic degradation of pollutants.  

PubMed

The last four decades have shown a remarkable increase in scientific interest in photocatalysis as a tool for tackling the world's energy and waste problems. The apparent similarity between photocatalytic water splitting and photocatalytic degradation of pollutants, which have been studied so far by two different scientific communities, raises the question regarding the extent to which one may utilize knowledge obtained in one field for the benefit of the other. This review examines the common features and differences between the two areas. The main similarities stem from the common dependence on the absorption of photons and on subsequent charge-carrier dynamics. The main dissimilarities are linked to thermodynamics, the type of reactants and end products, and to the role of adsorption and desorption. At present the fundamental differences between storing energy and using it to solve environmental issues affect practical solutions. Yet, easy transfer of knowledge, research resources, and personnel between the two is not only possible but should be encouraged. PMID:23754793

Pasternak, Sagi; Paz, Yaron

2013-06-10

245

Efficient Solar Energy Conversion Systems for Hydrogen Production from Water using Semiconductor Photoelectrodes and Photocatalysts  

NASA Astrophysics Data System (ADS)

Efficient solar energy conversion system for hydrogen production from water, solar-hydrogen system, is one of most important technologies for genuinely sustainable development of the society in the world wide scale. However, there are many problems to breakthrough such as low solar-to-H2 efficiency (STH), high cost, low stability, etc in order to realize the system practically and economically. The solar-hydrogen systems using semiconductors are mainly classified as follows; solar cell-electrolysis system, semiconductor photoelectrode system, and photocatalyst system. There are various merits and demerits in each system. The solar cell-electrolysis system is very efficient but is very high cost. The photocatalyst system is very simple and relatively low cost, but the efficiency is still very low. On the other hand, various semiconductor systems with high efficiency have been investigated. A high STH more than 10% was reported using non-oxide semiconductor photoelectrodes such as InGaP, while the preparation methods were costly. In a European project, some simple oxide semiconductor photoelectrodes such as Fe2O3 and WO3 are mainly studied. Here, we investigated various photoelectrodes using mixed metal oxide especially on BiVO4 semiconductor, and a high throughput screening system of new visible light responsible semiconductors for photoelectrode and photocatalyst. Moreover, photocatalysis-electrolysis hybrid system for economical H2 production is studied to overcome the demerit of photocatalyst system on the gas separation and low efficiency.

Sayama, K.; Arai, T.

2008-02-01

246

Photoinactivation of virus on iron-oxide coated sand: enhancing inactivation in sunlit waters.  

PubMed

Adsorption onto iron oxides can enhance the removal of waterborne viruses in constructed wetlands and soils. If reversible adsorption is not coupled with inactivation, however, infective viruses may be released when changes in solution conditions cause desorption. The goals of this study were to investigate the release of infective bacteriophages MS2 and ?X174 (two human viral indicators) after adsorption onto an iron oxide coated sand (IOCS), and to promote viral inactivation by exploiting the photoreactive properties of the IOCS. The iron oxide coating greatly enhanced viral adsorption (adsorption densities up to ? 10(9) infective viruses/g IOCS) onto the sand, but had no affect on infectivity. Viruses that were adsorbed onto IOCS under control conditions (pH 7.5, 10 mM Tris, 1250 ?S/cm) were released into solution in an infective state with increases in pH and humic acid concentrations. The exposure of IOCS-adsorbed MS2 to sunlight irradiation caused significant inactivation via a photocatalytic mechanism in both buffered solutions and in wastewater samples (4.9 log(10) and 3.3 log(10) inactivation after 24-h exposure, respectively). Unlike MS2, ?X174 inactivation was not enhanced by photocatalysis. In summary, IOCS enhanced the separation of viruses from the water column, and additionally provided a photocatalytic mechanism to promote inactivation of one of the surrogates studied. These qualities make it an attractive option for improving viral control strategies in constructed wetlands. PMID:22264797

Pecson, Brian M; Decrey, Loïc; Kohn, Tamar

2012-01-04

247

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

248

Potable water from waste water  

SciTech Connect

The idea of obtaining potable water from waste water is a psychologically difficult one for many people to accept. The tendency is to think that waste water is dirty and cannot be converted to clean water. This book describes significant advances in waste water treatment technology which make possible the control and/or removal of conventional pollutants, thus making potable water from waste water technically feasible today. Methods of waste water treatment and purification in varying stages of development are presented, based on information prepared by Dallas Water Utilities; SCS Engineers, Inc.; Gulf South Research Institute; University of Colorado; and AWWA. Ongoing experimental and pilot studies around the world are described. A discussion of contaminants associated with municipal waste water reuse as well as a chapter on health effects of reuse have been included. Possible approaches to educating the public about water reuse are also considered.

Gillies, M.T. (ed.)

1981-01-01

249

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.

250

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.

2012-01-01

251

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

252

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

253

Bending Water  

NSDL National Science Digital Library

In this activity, bend water with the help of static electricity. Discover how a comb can cause water flowing out of a faucet to bend in a unique direction. This activity guide includes a step-by-step instructional video.

Center, Saint L.

2013-02-25

254

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

255

Water Distribution  

NSDL National Science Digital Library

Grade 6-10 geography lesson plan evaluating population growth and water availability in the United States and in other countries. Students will learn how to draw bar graphs and develop plans of action for water scarcity problems.

2008-10-08

256

Microbiology: water  

SciTech Connect

Topics discussed in this literature review with 173 references dealing with the microbiology of aquatic ecosystems include microbial indicators of water pollution, and the microbial ecology of water. Solar radiation and naturally occurring microbial predators are important forces in the natural self-purification of polluted surface waters. The relationship between water quality and microbiology of river systems and natural lakes is discussed.(KRM)

Geldrich, E.E.

1982-06-01

257

Water electrolysis  

Microsoft Academic Search

The electrolysis of water is evaluated as a potentially efficient, low cost means of hydrogen production. The theoretical energy and voltage, current, and energy efficiencies of water electrolysis are considered. The present status of water electrolysis is reviewed, with attention given to caustic potash of soda electrolytes, electrode materials, diaphragms inserted between the electrodes, and the design of unipolar and

T. Takahashi

1979-01-01

258

Extraterrestrial Water  

Microsoft Academic Search

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

J. F. Kasting

2002-01-01

259

Water Ways  

ERIC Educational Resources Information Center

|In many communities, schools are among the largest facilities and house the highest concentrations of daytime population. They create a huge demand for water. Even in regions with abundant water supplies, an increase in demand stresses local capacity, and water becomes more expensive. However, with the help of innovative products that reduce…

Jahrling, Peter

2007-01-01

260

Water Treatment  

NSDL National Science Digital Library

This web site showcases Lenntech's Complete Water treatment and Air filtration solutions. This company designs, manufactures and installs complete air and water treatment system solutions. Lenntech proclaims, "Our wide range of technologies and extended know-how in all water-related sectors will guarantee you a cost-efficient solution meeting your water quality requirements." Whether or not you're looking to purchase one of these fine water treatment systems, the site will still provide beneficial resources about how said systems operate.

2008-09-17

261

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

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

Electrochemistry and electrocatalysis with heme proteins in chitosan biopolymer films  

Microsoft Academic Search

Protein–chitosan (CS) films were made by casting a solution of proteins and CS on pyrolytic graphite electrodes. Myoglobin (Mb), hemoglobin (Hb), and horseradish peroxidase (HRP) incorporated in CS films gave a pair of stable, well-defined, and quasi-reversible cyclic voltammetric peaks at about ?0.33V vs saturated calomel electrode in pH 7 buffers, respectively, while catalase (Ct) in CS films showed a

He Huang; Naifei Hu; Yonghuai Zeng; Gu Zhou

2002-01-01

264

Trends in electrocatalysis : from extended to nanoscale surfaces.  

SciTech Connect

One of the key objectives in fuel-cell technology is to improve and reduce Pt loading as the oxygen-reduction catalyst. Here, we show a fundamental relationship in electrocatalytic trends on Pt{sub 3}M (M=Ni, Co, Fe, Ti, V) surfaces between the experimentally determined surface electronic structure (the d-band centre) and activity for the oxygen-reduction reaction. This relationship exhibits 'volcano-type' behavior, where the maximum catalytic activity is governed by a balance between adsorption energies of reactive intermediates and surface coverage by spectator (blocking) species. The electrocatalytic trends established for extended surfaces are used to explain the activity pattern of Pt{sub 3}M nanocatalysts as well as to provide a fundamental basis for the catalytic enhancement of cathode catalysts. By combining simulations with experiments in the quest for surfaces with desired activity, an advanced concept in nanoscale catalyst engineering has been developed.

Stamenkovic, V. R.; Mun, B. S.; Arenz, M.; Mayrhofer, K. J. J.; Lucas, C. A.; Wang, G.; Ross, P. N.; Markovic, N. M.; Materials Science Division; Lawrence Berkeley Nat. Lab.; Technical Univ. Munich; Univ. of Liverpool; Univ. of South Carolina

2007-01-01

265

Particle size and structural effects in platinum electrocatalysis  

Microsoft Academic Search

Of the several factors which influence electrocatalytic activity, particle size and structural effects are of crucial importance, but their effects and mechanism of interaction,vis-a-vis overall performance, have been, at best, vaguely understood. The situation is further aggravated by the use of a wide range of experimental conditions resulting in non-comparable data. This paper attempts systematically to present the developments to

S. Mukerjee

1990-01-01

266

Microbial electrocatalysis with Geobacter sulfurreducens biofilm on stainless steel cathodes  

Microsoft Academic Search

Stainless steel and graphite electrodes were individually addressed and polarized at ?0.60V vs. Ag\\/AgCl in reactors filled with a growth medium that contained 25mM fumarate as the electron acceptor and no electron donor, in order to force the microbial cells to use the electrode as electron source. When the reactor was inoculated with Geobacter sulfurreducens, the current increased and stabilized

Claire Dumas; Régine Basseguy; Alain Bergel

2008-01-01

267

Solvothermal synthesis of platinum alloy nanoparticles for oxygen reduction electrocatalysis.  

PubMed

Platinum alloy nanoparticles show great promise as electrocatalysts for the oxygen reduction reaction (ORR) in fuel cell cathodes. We report here on the use of N,N-dimethylformamide (DMF) as both solvent and reductant in the solvothermal synthesis of Pt alloy nanoparticles (NPs), with a particular focus on Pt-Ni alloys. Well-faceted alloy nanocrystals were generated with this method, including predominantly cubic and cuboctahedral nanocrystals of Pt(3)Ni, and octahedral and truncated octahedral nanocrystals of PtNi. X-ray diffraction (XRD) and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM), coupled with energy dispersive spectroscopy (EDS), were used to characterize crystallite morphology and composition. ORR activities of the alloy nanoparticles were measured with a rotating disk electrode (RDE) technique. While some Pt(3)Ni alloy nanoparticle catalysts showed specific activities greater than 1000 ?A/cm(2)(Pt), alloy catalysts prepared with a nominal composition of PtNi displayed activities close to 3000 ?A/cm(2)(Pt), or almost 15 times that of a state-of-the-art Pt/carbon catalyst. XRD and EDS confirmed the presence of two NP compositions in this catalyst. HAADF-STEM examination of the PtNi nanoparticle catalyst after RDE testing revealed the development of hollows in a number of the nanoparticles due to nickel dissolution. Continued voltage cycling caused further nickel dissolution and void formation, but significant activity remained even after 20,000 cycles. PMID:22524269

Carpenter, Michael K; Moylan, Thomas E; Kukreja, Ratandeep Singh; Atwan, Mohammed H; Tessema, Misle M

2012-05-11

268

Electrocatalysis in solid oxide fuel cell electrode domains  

SciTech Connect

A significant improvement in power output is achieved by percolation of catalyst elements into the YSZ electrolyte surface during fabrication of a solid oxide fuel cell (SOFC). The resulting surface is referred to hereafter as a domain. The catalysts allow the electrochemical reactions to take place in the domain. Together with current collecting electrodes on the domains, a novel SOFC structure is fabricated. On the cathode domain Mn and Ce and on the anode domain Ni, Ru, and Pd are able to catalyze the reactions. The current and power densities of such cells are significantly higher than those obtained in the conventional sandwich type SOFC. The dispersion of electrocatalysts in the contain helps to achieve lower electrode overpotentials, because of its nanometric size. A redox mechanism is invoked for the catalysts in the domain. By using a less efficient oxygen reduction electrocatalyst such as Pt over the domains, it is shown that the electrode reaction occurs more easily in the domain and the contribution from the electronically conducting layer is predominantly charge collection. A friable layer of lanthanum strontium manganite can function as a good contact cathode over the domain. Pure Ni paint when applied over anodic domains is an excellent contact electrode.

Thampi, K.R.; McEvoy, A.J.; Van Herle, J. [Ecole Polytechnique Federale de Lausanne (Switzerland). Inst. de Chimie Physique

1995-02-01

269

Block copolymer lithography of rhodium nanoparticles for high temperature electrocatalysis.  

PubMed

We present a method for forming ordered rhodium nanostructures on a solid support. The approach makes use of a block copolymer to create and assemble rhodium chloride nanoparticles from solution onto a surface; subsequent plasma and thermal processing are employed to remove the polymer and fully convert the nanostructures to metallic rhodium. Films cast from a solution of the triblock copolymer poly(styrene-b-2-vinyl pyridine-b-ethylene oxide) dissolved in toluene with rhodium(III) chloride hydrate were capable of producing a monolayer of rhodium nanoparticles of uniform size and interparticle spacing. The nanostructures were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. The electrocatalytic performance of the nanoparticles was investigated with AC impedance spectroscopy. We observed that the addition of the particles to a model solid oxide fuel cell anode provided up to a 14-fold improvement in the anode activity as evidenced by a decrease in the AC impedance resistance. Examination of the anode after electrochemical measurement revealed that the basic morphology and distribution of the particles were preserved. PMID:23713545

Boyd, David A; Hao, Yong; Li, Changyi; Goodwin, David G; Haile, Sossina M

2013-06-11

270

Electrocatalysis of anodic oxygen-transfer reactions: Evolution of ozone  

Microsoft Academic Search

Current efficiencies are compared for the generation of O[sub 3] simultaneously with O[sub 2] during anodic discharge of H[sub 2]O at pure and iron(III)-doped [beta]-lead dioxide film electrodes in phosphate buffer (pH 7.5, 10 C) containing 2.5 mM KF. Also examined is the effect of applied current density. A current efficiency of 14.6% was obtained for the Fe(III)-doped PbO[sub 2

J. Feng; D. C. Johnson; S. N. Lowery; J. J. Carey

1994-01-01

271

Synthesis of a CNT-grafted TiO2 nanocatalyst and its activity triggered by a DC voltage  

NASA Astrophysics Data System (ADS)

Carbon nanotube (CNT)-grafted TiO2 (CNT/TiO2) was synthesized as an electrically conductive catalyst that exhibits redox ability under electrical excitation besides ultraviolet (UV) irradiation. The CNT/TiO2 material was synthesized by a two-step process. Ni nanoparticles were photodeposited onto TiO2 first. The Ni nanoparticles then served as seeds for the growth of CNTs using the chemical vapor deposition (CVD) of C2H2. The CNT/TiO2 nanocomposite exhibits strong oxidation activity toward NO gas molecules via both photocatalysis under UV irradiation and electrocatalysis under a DC voltage of 500 V in dark conditions.

Kuo, Chien-Sheng; Tseng, Yao-Hsuan; Lin, Hong-Ying; Huang, Chia-Hung; Shen, Chih-Yen; Li, Yuan-Yao; Shah, S. Ismat; Huang, Chin-Pao

2007-11-01

272

Falling Water  

NSDL National Science Digital Library

Students drop water from different heights to demonstrate the conversion of waterâs 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

273

Water Exploration  

NSDL National Science Digital Library

Water Exploration uses a project-based learning approach, permitting students to conduct research and build an understanding about water science and critical water-related issues. All learning activities and resources are packaged into three modules, or Legacy Cycles, in a way that enhances student learning by making use of the Internet and computer technology to promote inquiry learning. The Earth Science Literacy Principles provide the organizing framework for the lessons and activities in each Water Exploration Legacy Cycle. The curriculum is applicable to high school science courses such as Earth and Space Science, Advanced Placement Environmental Science, Biology, Chemistry, and Aquatic Science.

Ellins, Kathy K.; Mccall, Linda R.; Mote, Alison; Ryan, Catherine; Negrito, Kathleen M.; Paloski, Brenda

2012-01-01

274

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

275

Water Dictionary  

NSDL National Science Digital Library

This resource from the United States Geological Survey contains a list of water-related terms that will help you to understand and use the USGS web site. If you are looking for a more detailed water dictionary or glossary, this page also points you in that direction.

2008-06-03

276

Cleaning Water  

NSDL National Science Digital Library

In third world countries contaminated water kills 400 children under the age of five every hour. This radio broadcast reports on a new method to disinfect the water by running it under a UV lamp. The clip is 2 minutes in length.

277

Red Water  

Microsoft Academic Search

IN connection with the letters on ``red water'' in NATURE of April 4 and 11, it may be of interest to state that a rusty-red coloration of brine and salt in evaporating pools of sea water is common on this coast.

Cyril Crossland

1912-01-01

278

WATER TREATMENT  

DOEpatents

An automated system for adding clarifying chemicals to water in a water treatment plant is described. To a sample of the floc suspension polyacrylamide or similar filter aid chemicals are added, and the sample is then put through a fast filter. The resulting filtrate has the requisite properties for monitoring in an optical turbidimeter to control the automated system. (AEC)

Pitman, R.W.; Conley, W.R. Jr.

1962-12-01

279

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

280

Water Pressure. Water in Africa.  

ERIC Educational Resources Information Center

The Water in Africa Project was realized over a 2-year period by a team of Peace Corps volunteers. As part of an expanded, detailed design, resources were collected from over 90 volunteers serving in African countries, photos and stories were prepared, and standards-based learning units were created for K-12 students. This unit, "Water Pressure,"…

Garrett, Carly Sporer

281

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.

282

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.

2000-01-01

283

A novel scheelite-like structure of BaBi 2Mo 4O 16: Photocatalysis and investigation of the solid solution, BaBi 2Mo 4? x W x O 16 (0.25 ? x ? 1)  

Microsoft Academic Search

A barium bismuth molybdate, BaBi2Mo4O16, was synthesized for the first time. The compound was made by the solid-state technique and studied for photocatalytic degradation of water pollutants. The compound crystallizes in the monoclinic C2\\/c system with a=5.317 (1)Å, b=12.875 (2)Å, c=19.390 (3)Å, ?=101.512 (4)°, V=1327.1 (4)Å3 and Z=4. The crystal structure along the a-axis consists of layers of [Bi2O2] units

B. Muktha; Giridhar Madras; T. N. Guru Row

2007-01-01

284

Water Purification.  

National Technical Information Service (NTIS)

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 c...

1994-01-01

285

Water Spout  

NASA Astrophysics Data System (ADS)

During the AAPT summer meeting at Creighton University in 2011, Vacek Miglus and I took pictures of early apparatus at the Creighton physics department. The apparatus in the left-hand picture, shown with the spigot closed, appeared to be a liquid-level device: the water level was the same in both the narrow tube and the flaring glass vase. However, when I came back nine months later to give a talk about the apparatus, I realized that it was really an early Bernoulli effect demonstration. In the right-hand picture the spigot is open and water can be seen coming out of the spout. The water level in the narrow tube has fallen appreciably, thus showing that the pressure at this point has decreased, in agreement with the non-zero velocity of the water in the horizontal tube. The device was made ca. 1880 by E. S. Ritchie of Boston, MA. (Photos by Thomas B. Greenslade Jr.)

Greenslade, Thomas B.

2013-02-01

286

WATER QUALITY  

EPA Science Inventory

This manual was develped to provide an overview of microfiltration and ultrafiltration technology for operators, administrators, engineers, scientists, educators, and anyone seeking an introduction to these processes. Chapters on theory, water quality, applications, design, equip...

287

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.

Ieee

2013-07-08

288

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

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 Nozzles  

NASA Astrophysics Data System (ADS)

The following type of nozzle problem is found in some introductory-level physics textbooks.1-3 The (average) flow speed of water through and out a hose with a cross-sectional area AH is vH. If a nozzle with an exit area AN < AH is attached to the hose, what is the speed vN of the water out of it? The books simply apply the continuity equation AHvH = ANvN to the nozzle to obtain vN = (AH/AN)vH. This solution is not correct because it does not take account of the fact that attaching the nozzle to the hose reduces the flow speed in it. So the books' values of vN must always be too high, sometimes by large amounts. It should not seem surprising that it takes more time to fill a watering can with a garden hose when there is a nozzle at the end of it than when there isn't. This paper will explain how a water nozzle actually works, and for a situation with a simple water source, the correct flow speed from a nozzle will be derived.

Humbert, Richard

2005-12-01

291

Photocatalytic degradation pathway of methylene blue in water  

Microsoft Academic Search

The TiO2\\/UV photocatalytic degradation of methylene blue (MB) has been investigated in aqueous heterogeneous suspensions. In addition to a prompt removal of the color, TiO2\\/UV-based photocatalysis was simultaneously able to oxidize the dye, with an almost complete mineralization of carbon and of nitrogen and sulfur heteroatoms into CO2, NH4+, NO3? and SO42?, respectively. A detailed degradation pathway has been determined

Ammar Houas; Hinda Lachheb; Mohamed Ksibi; Elimame Elaloui; Chantal Guillard; Jean-Marie Herrmann

2001-01-01

292

Water watch  

SciTech Connect

This issue of [open quotes]Water Watch[close quotes] focuses on summer streamflow. In addition, a summary of streamflow, soil moisture, and water supply conditions through the end of May is presented. In addition, short-term streamflow forecasts are given. Forecasts are based on the National Weather Service US Climate Analysis Center's 90-day outlook. Temperature and precipitation probability estimates given in the outlook are based primarily on the average of monthly forecasts since 1974 and seasonal forecasts since 1959 at 100 US weather reporting stations. Regional analyses are based on reports and data provided by the National Weather Service Office of Hydrology and River Forecast Centers, the US Department of Agriculture, the Bureau of Reclamation, the Soil Conservation Service, the California Department of Water Resources, and the US Geological Survey. For purposes of reporting, the US is divided into six regions. The data presented can be used to observe how weather conditions affect hydro generation in April.

Gruber, N.

1993-06-01

293

Water watch  

SciTech Connect

This issue of [open quotes]Water Watch[close quotes] focuses on soil moisture and fall streamflow, particularly in the Western US. The information is based on reports and data provided by the National Weather Service Office of Hydrology, the US Dept. of Agriculture, the Bureau of Reclamation, the Soil Conservation Service, the California Dept. of Water Resources, and the US Geological Survey. Ninety-day outlooks are through October 1992. For purposes of reporting, the US is divided into six regions. The data can be used to observe how weather conditions affected hydro generation in July.

Not Available

1992-10-01

294

Reuse of Regenerated Waters Under Water Scarcity  

Microsoft Academic Search

\\u000a Mediterranean countries face water supply challenges due to water scarcity. Water regeneration, recycling and reuse address\\u000a these challenges by resolving water resource issues and creating new sources of high-quality water supplies. Among others,\\u000a industrial activities worldwide account for about a quarter of all water consumption and there is hardly any industry that\\u000a does not use large amounts of water. Water

I. Ortiz; R. Ibáñez; A. M. Urtiaga; P. Gómez

295

Water and Water Vapor Penetration Through Coatings  

Microsoft Academic Search

Water and water vapor transport in two-layer systems where one layer acts as water retarder are analyzed. In the experimental work, four external paints supposed to protect the underlying structure against water under common service conditions are applied on glass fiber reinforced concrete substrates. The water absorption coefficient and the effective water vapor diffusion coefficient are chosen as evaluation parameters

Jitka Podêbradská; Jaroslava Drchalová

2002-01-01

296

Blue Water  

USGS Multimedia Gallery

The Canadian Coast Guard Ship Louis S. St-Laurent has a mechanical system that creates bubbles that rise to the surface and push ice away from the ship's hull. It also happens to churn the water into an amazing shade of blue....

2010-02-19

297

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

298

Water Sampling  

USGS Multimedia Gallery

On April 20, 2010, the Deepwater Horizon Drilling Platform exploded and sank, causing an enormous oil spill in the Gulf of Mexico. U.S. Geological Survey field offices responded immediately by organizing teams to take pre-spill sediment and water samples in order to establish a baseline survey. This...

2010-06-04

299

Water watch  

SciTech Connect

In this issue of Water Watch, a summary of precipitation, drought, and streamflow conditions during the summer is presented. In addition, short-term streamflow forecasts (through October) for each region are given. For purposes of reporting, the US is divided into six regions. The data presented can be used to observe how weather conditions affected hydro generation in July.

Not Available

1991-10-01

300

Parasites: Water  

MedlinePLUS

... Developing World: A Handbook for Implementing Household-Based Water Treatment and Safe Storage Projects Email page link Print page Get email updates Subscribe to RSS Listen to audio/Podcast Contact Us: Centers for Disease Control and Prevention 1600 ... and Training CDC Bottle Bioassay References and ...

301

Water Filtration  

ERIC Educational Resources Information Center

|A water filtration column is devised by students using a two-liter plastic bottle containing gravel, sand, and activated charcoal, to test the filtration potential of the column. Results indicate that the filtration column eliminates many of the contaminating materials, but does not kill bacteria.|

Jacobsen, Erica K.

2004-01-01

302

A review of the mechanisms and modeling of photocatalytic disinfection  

Microsoft Academic Search

This paper is a review of the fundamental disinfection mechanisms of photocatalysis and the models used to fit the disinfection process. Photocatalysis is an attractive technology for water treatment largely due to its potential to utilize solar energy directly and achieve both disinfection and chemical detoxification. Many papers have been published on photocatalytic disinfection, but there is still considerable debate

Omatoyo K. Dalrymple; Elias Stefanakos; Maya A. Trotz; D. Yogi Goswami

2010-01-01

303

Water from (waste)water--the dependable water resource.  

PubMed

Water reclamation and reuse provides a unique and viable opportunity to augment traditional water supplies. As a multi-disciplined and important element of water resources development and management, water reuse can help to close the loop between water supply and wastewater disposal. Effective water reuse requires integration of water and reclaimed water supply functions. The successful development of this dependable water resource depends upon close examination and synthesis of elements from infrastructure and facilities planning, wastewater treatment plant siting, treatment process reliability, economic and financial analyses, and water utility management. In this paper, fundamental concepts of water reuse are discussed including definitions, historical developments, the role of water recycling in the hydrologic cycle, categories of water reuse, water quality criteria and regulatory requirements, and technological innovations for the safe use of reclaimed water. The paper emphasizes the integration of this alternative water supply into water resources planning, and the emergence of modern water reclamation and reuse practices from wastewater to reclaimed water to repurified water. PMID:12019829

Asano, Takashi

2002-01-01

304

New Mexico Water Rights.  

National Technical Information Service (NTIS)

The booklet summarizes water rights concepts in general, and specifically, how those concepts apply to water law in New Mexico. Topics covered include: a historical perspective of water, the nature of water, the riperian doctrine of water use, the doctrin...

L. G. Harris

1984-01-01

305

The Water Cycle  

NSDL National Science Digital Library

4th Grade Science Learn all about the Water Cycle! The Water Cycle: Water Storage Learn about Evaporation, Condensation, Precipitation, and Collection! The Water Cycle Here are some activites to learn about the water cycle. Hydrologic Cycle ...

Andrus, Ms.

2007-10-12

306

Water watch  

SciTech Connect

This issue of [open quotes]Water Watch[close quotes] focuses on soil moisture and fall streamflow. A map depicts soil moisture conditions in the US through early October. The analysis is based on reports and data provided by the National Weather Service Office of Hydrology, the US Department of Agriculture, the Bureau of Reclamation, the Soil Conservation Service, the California Department of Water Resources, and the US Geological Survey. Ninety-day outlooks are through November 1992. For purposed of reporting, the US is divided into six regions as indicated on a figure and in a table. The data presented in the table, the Hydropower Generation Report, can be used to observe how weather conditions affected hydro generation in September.

Gruber, N. (C.T. Male Associates, P.C., Syracuse, NY (United States))

1992-12-01

307

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.

308

Water Sports  

NSDL National Science Digital Library

Water Sports Web page is organized by tours, equipment, schools and stores, with links to industry home pages, trade organizations, clubs, preservation projects and other related pages. Still in progress is a hierarchical system of links beginning with your choice of whitewater or touring categories. Find information on The North American Paddlesports Association (NAPSA) and an alphabetical list of companies that are Trade Association of Sea Kayaking (TASK) and/or NAPSA members.

309

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

310

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

311

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.

312

Campus Water Uses and Potential Water Efficiencies  

Microsoft Academic Search

With recent increases in the price of water, saving water has become one of the main focuses for sustainability. The California Institute of Technology used 200,000,000 gallons of water in the year 2008; however the institute has never tracked this water to its destination within the campus. Using data collected from water meters on campus and from the utility company

Calvin Kuo; Melany Hunt; John Onderdonk; Matthew Berbee

2008-01-01

313

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.

314

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.

315

Discovering the Water Cycle!  

NSDL National Science Digital Library

We will be learning about what the water cycle is and how it works. Resources! The Hydrologic Cycle: Water's journey through time The Water Cycle Thirstin's Water Cycle Activity Water evaporates from the surface Water Wonders These are a collection of websites that are going to help us in our journey of discovering what the water cycle is. ...

Mortensen, Miss

2009-10-09

316

Water watch  

SciTech Connect

This issue of [open quotes]Water Watch[close quotes] focuses on soil moisture conditions across the country as of the first of April. In addition, the department describes streamflow conditions across the US forecast for April through July. The information presented is based on data from the US Geological Survey, the National Weather Service, and the Soil Conservation Service. For purposes of providing this information, the US is divided into six regions. The Hydropower Generation Report can be used to observe how weather conditions affected hydro generation in March.

Not Available

1991-06-01

317

Water Resources of Alaska  

NSDL National Science Digital Library

The Water Resources of Alaska homepage is provided by the US Geological Survey. The goal of this project is to study and understand Alaska's hydrology (surface water, ground water, and water quality) for use and management of the nation's water resources. The site features a list of published reports and information about current projects as well as a vast amount of hydrologic data such as surface water, ground water, water quality, glaciers, water use, and hydrologic data reports.

Geological Survey (U.S.). Water Resources Division. Alaska District.

1999-01-01

318

Water Resources of Wisconsin  

NSDL National Science Digital Library

This U.S. Geological Survey (USGS)website provides water data, online publications, a list of USGS - Wisconsin publications, and links to water resource projects and studies in Wisconsin. The water data consists of real-time streamflow, quarterly streamflow reports, water levels measured by a ground-water observation network of 140 wells throughout Wisconsin, and NWISWeb (National Water Information System on the Web) data (consisting of real-time streamflow, ground level water, surface water and water quality data).

319

Water Resources Data Arizona Water Year 2002  

USGS Publications Warehouse

The Arizona District water data report includes records on both surface water and ground water in the State for water year 2002. Specifically, it contains: (1) discharge records for 201 streamflow-gaging stations, for 29 crest-stage, partial-record streamflow stations, and 48 miscellaneous sites; (2) stage and (or) content only records for 10 lakes and reservoirs; (3) water-quality records for 21 streamflow-gaging stations and 65 wells; and (4) water levels for 18 wells.

McCormack, H. F.; Fisk, G. G.; Duet, N. R.; Evans, D. W.; Roberts, W. P.; Castillo, N. K.

2003-01-01

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

Water watch  

SciTech Connect

The Hydropower Generation Report provides generation figures for the largest hydropower producers in each of six regions in the US. The report compares, for each month, the amount of hydroelectricity generated (in thousands of megawatt-hours) by each producers in the last two years to the ten-year average for that month. This database is used to figure long-term generation averages and percent of averages. The producers regularly provide current generation data to update the database. This issue of [open quotes]Water Watch[close quotes] focuses on winter snow conditions across the US as of mid-January. In addition, the department provides an outlook of spring flood potential. The information presented is based on data from the US Geological Survey, the National Weather Service, and the Soil Conservation Service.

Not Available

1991-02-01

322

Cleaner Water through Conservation.  

National Technical Information Service (NTIS)

The document explains the relationship between the quantity of water and its quality and discusses how developing water-use efficiency programs can help states and local communities achieve cleaner water through conserving water.

1995-01-01

323

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, ...

324

Bottled Water Basics  

MedlinePLUS

... limitations set in the bottled water quality standards. Mineral water - Ground water that naturally contains 250 or ... the quality of its source, including its natural mineral content. Most bottled water comes from a ground ...

325

Effect of Water Pressure on Water Use.  

National Technical Information Service (NTIS)

Three approaches were used in this study to document the effect of water pressure on water use. Water usage in different pressure zones was compared for areas in Denver, Colo. In the Los Feliz area of Los Angeles, water-use records were analyzed where wat...

L. N. Hoag

1984-01-01

326

Everyone into the Water!  

ERIC Educational Resources Information Center

|As the days grow longer and warmer with the approach of summer, everyone's thoughts turn to the outdoors and the clear blue of water sports. While recreational choices range from in-the-water activities like water polo to under-the-water sports like free diving, and on-the-water diversions like water skiing, this article focuses on print, video,…

Hennessey, Christina L.

2007-01-01

327

Physiological Water Model Development.  

National Technical Information Service (NTIS)

The water of the human body can be categorized as existing in two main compartments: intracellular water and extracellular water. The intracellular water consists of all the water within the cells and constitutes over half of the total body water. Since r...

S. Doty

1993-01-01

328

Contested water rights  

Microsoft Academic Search

In many international river basins disputes over property rights to water lead to inefficient water allocation and a waste of resources. In this paper, we examine how contested water rights impede water trade. To show this, we use a model in which property rights to water are contested because countries have overlapping claims to water. In the model, countries decide

Erik Ansink; Hans-Peter Weikard

2009-01-01

329

The Water Cycle  

NSDL National Science Digital Library

Students will understand and explain parts of the water cycle. First watch the video to get a background about the water cycle: water cycle video Draw and explain the water cycle in your own words (include the terms: evaporation, condensation, precipitation, at least 3 bodies of water, the sun). Before reading the experiment record your predictions: If you put a small amount of water ...

Amanda, Miss

2011-02-14

330

WRAMS, sustainable water recycling  

Microsoft Academic Search

The Water Reclamation and Management Scheme (WRAMS) at Sydney Olympic Park was built as part of the Olympic Games in 2000. The Scheme was designed to treat raw domestic sewage into recycled water which is then sold back to consumers. The main elements of WRAMS are a water reclamation plant, a water treatment plant, storm water collection, clean water storage

H. Chapman

2006-01-01

331

Water Resources Data, Utah, Water Year 2002  

USGS Publications Warehouse

Water-resources data for the 2002 water year for Utah consist of records of stage, discharge, and water quality of streams; stage and contents of lakes and reservoirs; and water levels and water quality of ground water. This report contains discharge records for 163 gaging stations; stage and contents for 10 lakes and reservoirs; water quality for 24 hydrologic stations, and 64 wells; water levels for 66 observation wells; and precipitation for 2 stations. Additional water data were collected at various sites not involved in the systematic data-collection program and are published as miscellaneous measurements. These data represent that part of the National Water Data System collected by the U.S. Geological Survey and cooperating State and Federal agencies in Utah.

Wilberg, D. E.; Tibbetts, J. R.; Enright, Michael

2003-01-01

332

Water resources data, Utah, water year 2004  

USGS Publications Warehouse

Water-resources data for the 2004 water year for Utah consist of records of stage, discharge, and water quality of streams; stage and contents of lakes and reservoirs; and water levels and water quality of ground water. This report contains discharge records for 156 gaging stations; stage and contents for 8 lakes and reservoirs; water quality for 16 hydrologic stations, and 29 wells; water levels for 67 observation wells; and precipitation for 3 stations. Additional water data were collected at various sites not involved in the systematic data-collection program and are published as miscellaneous measurements. These data represent that part of the National Water Data System collected by the U.S. Geological Survey and cooperating State and Federal agencies in Utah.

Enright, Michael; Wilberg, D. E.; Tibbetts, J. R.

2005-01-01

333

Municipal Water Demand and Conservation: Western Water  

Microsoft Academic Search

account for the impact of population growth. This study found that during mandatory water restrictions, water use savings measured in expected use per capita ranged from 18-56%, about 4-6% greater than using direct comparison of water use between years. Mandatory water restrictions were far more effective than voluntary water restrictions that only saw a reduction of 4-12%. Consistent with previous

Bobbie Klein; Christina Alvord

334

Removal of emergent contaminants: integration of ozone and photocatalysis.  

PubMed

A mixture of nine pharmaceuticals has been treated by means of the systems: UV-B(313 nm), O(3), UV-B(313 nm) + TiO(2), O(3) + UV-B(313 nm), and O(3) + UV-B(313 nm)+TiO(2). Simple photolytic or ozonation processes lead to a deficient total organic carbon (TOC) elimination after 120 min of exposure (25 and 30% conversions, respectively). Addition of a photocatalyst such as titanium dioxide significantly enhanced the mineralization degree, a 60% TOC conversion was obtained. A TiO(2) load optimum around 0.25 g L(-1) was observed. No loss in photoactivity was experienced after 2 reuses. Due to ozone photodegradation, the combination of ozone and radiation increased the generation of hydroxyl radicals. As a consequence, TOC removal was increased to a value in the proximity of 85%. The most complex system, O(3) + UV-B(313 nm) + TiO(2), achieved the highest TOC abatement (95%). Use of ozone in photocatalytic processes involves an increase in hydroxyl radical generation. PMID:22343613

Rivas, F Javier; Beltrán, Fernando J; Encinas, Angel

2012-02-15

335

Solar light induced degradation of reactive dye using photocatalysis.  

PubMed

Outdoors experiment with natural solar light instead of using artificial UV light was also conducted to investigate alternative energy source applicability on organics degradation. The results of this study were as follows. Degradation of the reactive dye, Red 120, with TiO2/solar light was enhanced by augmentation in TiO2 loading, and UV light intensity but was inhibited by increase in initial dye concentration. With both solar light illumination and TiO2 present, reactive dye was more effectively eliminated than with either solar light or TiO, alone. Photocatalytic removal efficiency of reactive dye increased with increasing TiO2 dosage. However, over 1.5 gL(-1) of TiO2 dosage, the efficiency reached a plateau. The degradation rate of reactive dye, Red 120, was strongly dependent on initial dye concentration, and all the experimental data were fit to the first-order rate equation. Photocatalytic degradation of reactive dye increased linearly with increasing UV light intensity. It is found that the presence of thick clouds in the sky markedly increased the time required for degradation of reactive dye. On the basis of these experimental observations, the photo-oxidation degradation of reactive dye using TiO2 under solar light irradiation can be feasible application of the advanced oxidation process. PMID:15030149

Park, Jae-Hong; Cho, Il-Hyoung; Kim, Young-Gyu

2004-01-01

336

Aqueous degradation of diclofenac by heterogeneous photocatalysis using nanostructured materials  

Microsoft Academic Search

The photocatalytic degradation of diclofenac (DIC), 2-[2?, 6?-(dichlorophenyl)amino]phenylacetic acid is investigated under near UV–Vis and UV irradiation, using commercial TiO2 P25, synthesized TiO2 (anatase and rutile) and functionalized multi-walled carbon nanotube (MWCNTox): anatase (10-MWCNTox–TiO2) suspensions as catalysts. Factors affecting the kinetics of the process, such as the type and load of photocatalyst, and the presence of dissolved O2, or addition

C. Martínez; M. I. Fernández; J. A. Santaballa; J. Faria

2011-01-01

337

Improving carbon nitride photocatalysis by supramolecular preorganization of monomers.  

PubMed

Here we report a new and simple synthetic pathway to form ordered, hollow carbon nitride structures, using a cyanuric acid-melamine (CM) complex in ethanol as a starting product. A detailed analysis of the optical and photocatalytic properties shows that optimum hollow carbon nitride structures are formed after 8 h of condensation. For this condensation time, we find a significantly reduced fluorescence intensity and lifetime, indicating the formation of new, nonradiative deactivation pathways, probably involving charge-transfer processes. Enhanced charge transfer is seen as well from a drastic increase of the photocatalytic activity in the degradation of rhodamine B dye, which is shown to proceed via photoinduced hole transfer. Moreover, we show that various CM morphologies can be obtained using different solvents, which leads to diverse ordered carbon nitride architectures. In all cases, the CM-C3N4 structures exhibited superior photocatalytic activity compared to the bulk material. The utilization of CM hydrogen-bonded complexes opens new opportunities for the significant improvement of carbon nitride synthesis, structure, and optical properties toward an efficient photoactive material for catalysis. PMID:23647353

Shalom, Menny; Inal, Sahika; Fettkenhauer, Christian; Neher, Dieter; Antonietti, Markus

2013-05-07

338

Photocatalysis and radiation absorption in a solar plant  

Microsoft Academic Search

Recently, many papers have appeared in literature about photocatalytic detoxification. However, progress from laboratory data to the industrial solar reactor is not easy. Kinetic models for heterogeneous catalysis can be used to describe the photocatalytic processes, but luminic steps, related to the radiation, have to be added to the physical and chemical steps considered in heterogeneous catalysis. Thus, the evaluation

D. Curcó; S. Malato; J. Blanco; J. Giménez

1996-01-01

339

ZnS nano-architectures: photocatalysis, deactivation and regeneration  

NASA Astrophysics Data System (ADS)

An ``infinite recycling'' method for enhancing the durable applications of a ZnS nano-photocatalyst is shown. Based on the finding of thermodynamic stable nanophase of ZnS, we designed a strategy in which the deactivated ZnS nano-photocatalyst could be recovered into its original state. This ZnS photocatalyst can be used repeatedly without being released into environment as nano-waste. The strategy uses material highly efficiently and is environmentally friendly.An ``infinite recycling'' method for enhancing the durable applications of a ZnS nano-photocatalyst is shown. Based on the finding of thermodynamic stable nanophase of ZnS, we designed a strategy in which the deactivated ZnS nano-photocatalyst could be recovered into its original state. This ZnS photocatalyst can be used repeatedly without being released into environment as nano-waste. The strategy uses material highly efficiently and is environmentally friendly. Electronic supplementary information (ESI) available: Experiment details: control experiments for photodegradation of eosin B; BET measurements of ZnS at different states; the thermodynamically stable nanophases of ZnS and CdS. See DOI: 10.1039/c0nr00171f

Chen, Dagui; Huang, Feng; Ren, Guoqiang; Li, Dongsong; Zheng, Meng; Wang, Yongjing; Lin, Zhang

2010-10-01

340

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

341

Photocatalysis of chloroform decomposition by the hexachlororuthenate(IV) ion.  

PubMed

Dissolved hexachlororuthenate(IV) effectively catalyzes the photodecomposition of chloroform to hydrogen chloride and phosgene under near-UV (? > 345 nm) irradiation, whereby RuCl6(2-) is not itself photocatalytically active, but is photochemically transformed into a species that is active, possibly RuCl5 (CHCl3 )(-) . Conversion to a photoactive species during irradiation is consistent with the acceleration of the decomposition rate during the early stages and with the apparent inverse dependence of the decomposition rate on the initial concentration of RuCl6(2-) . The displacement of Cl(-) by CHCl3 in the coordination sphere to create the photoactive species is consistent with the retardation of photodecomposition by both Cl(-) and H2 O. The much smaller photodecomposition rate in CDCl3 suggests that C-H bond dissociation occurs during the primary photochemical event, which is also consistent with the presence of a CHCl3 molecule in the first coordination sphere. PMID:23050803

Chan, Alissa M; Peña, Laura A; Segura, Rosa E; Auroprem, Ramya; Harvey, Brent M; Brooke, Caroline M; Hoggard, Patrick E

2012-11-08

342

Hierarchically organized nanostructured TiO2 for photocatalysis applications  

NASA Astrophysics Data System (ADS)

A template-free process for the synthesis of nanocrystalline TiO2 hierarchical microstructures by reactive pulsed laser deposition (PLD) is here presented. By a proper choice of deposition parameters a fine control over the morphology of TiO2 microstructures is demonstrated, going from classical compact/columnar films to a dense forest of distinct hierarchical assemblies of ultrafine nanoparticles (<10 nm), up to a more disordered, aerogel-type structure. Correspondingly, the film density varies with respect to bulk TiO2 anatase, with a degree of porosity going from 48% to over 90%. These structures are stable with respect to heat treatment at 400 °C, which results in crystalline ordering but not in morphological changes down to the nanoscale. Both as deposited and annealed films exhibit very promising photocatalytic properties, even superior to standard Degussa-P25 powder, as demonstrated by the degradation of stearic acid as a model molecule. The observed kinetics are correlated to the peculiar morphology of the PLD grown material. We show that the 3D multiscale hierarchical morphology enhances reaction kinetics and creates an ideal environment for mass transport and photon absorption, maximizing the surface area-to-volume ratio while at the same time providing readily accessible porosity through the large inter-tree spaces that act as distributing channels. The reported strategy provides a versatile technique to fabricate high aspect ratio 3D titania microstructures through a hierarchical assembly of ultrafine nanoparticles. Beyond photocatalytic and catalytic applications, this kind of material could be of interest for those applications where high surface-to-volume and efficient mass transport are required at the same time.

Di Fonzo, F.; Casari, C. S.; Russo, V.; Brunella, M. F.; Bassi, A. Li; Bottani, C. E.

2009-01-01

343

Integration of Solar Photocatalysis and Membrane Bioreactor for Pesticides Degradation  

Microsoft Academic Search

Wastewater containing recalcitrant contaminants as pesticides can be treated by a coupled system which consists of a solar photo-Fenton pretreatment followed by a biological oxidation process. Membrane bioreactor technology (MBR) is particularly suitable for advanced biological treatment of wastewater containing biorecalcitrant compounds and shows a variety of advantages that make it a good alternative to be coupled with photo-Fenton, especially

J. L. Casas López; A. Cabrera Reina; E. Ortega Gómez; M. M. Ballesteros Martín; S. Malato Rodríguez; J. A. Sánchez Pérez

2010-01-01

344

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...

345

[2+2] Cycloadditions by Oxidative Visible Light Photocatalysis  

PubMed Central

Photochemical reactions are remarkable for their ability to easily assemble cyclobutanes and other strained ring systems that are difficult to construct using other conventional synthetic methods. We have previously shown that Ru(bpy)32+ is an efficient photocatalyst that promotes the [2+2] cycloadditions of electron-deficient olefins with visible light. Here, we show that Ru(bpy)32+ is also an effective photocatalyst for the [2+2] cycloaddition of electron-rich olefins. This transformation is enabled by the versatile photoelectrochemical properties of Ru(bpy)32+, which enables either one-electron reduction or one-electron oxidation of interesting organic substrates under appropriate conditions.

Ischay, Michael A.; Lu, Zhan; Yoon, Tehshik P.

2010-01-01

346

Carbon-modified TiO2 for photocatalysis  

NASA Astrophysics Data System (ADS)

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.

Wojtoniszak, Malgorzata; Dolat, Diana; Morawski, Antoni; Mijowska, Ewa

2012-04-01

347

Degradation of methylene blue via photocatalysis of titanium dioxide  

Microsoft Academic Search

Titanium dioxide nano-crystalline thin films on glass, polycarbonate, polymethyl methacrylate, and aluminum were prepared via a sol–gel process using different alkoxide precursors. All specimens exhibited nano-sized (<10nm) crystals of the anatase phase with a very tiny amount of brookite phase. The surface morphology of the thin film was influenced by the nature of the substrate. As the thickness of the

Chul Han Kwon; Hyunmin Shin; Je Hun Kim; Woo Suk Choi; Ki Hyun Yoon

2004-01-01

348

Radical Cation Diels-Alder Cycloadditions by Visible Light Photocatalysis  

PubMed Central

Ruthenium(II) polypyridyl complexes promote the efficient radical cation Diels–Alder cycloaddition of electron-rich dienophiles upon irradiation with visible light. These reactions enable facile [4+2] cycloadditions that would be electronically mismatched under thermal conditions. Key to the success of this methodology is the availability of ligand-modified ruthenium complexes that enable the rational tuning of electrochemical properties of the catalyst without significantly perturbing the overall photophysical properties of the system.

Lin, Shishi; Ischay, Michael A.; Fry, Charles G.; Yoon, Tehshik P.

2011-01-01

349

Synthesis of Barium Ferrite for Visible Light Photocatalysis Applications  

Microsoft Academic Search

Orthorhombic phase BaFe(2)O(4) powder was synthesized by using a solid state reaction method and investigated for its visible light photocatalytic properties. The crystallization of the structural phase was found to occur at a temperature above 1000 degrees C yielding a pure orthorhombic phase BaFe(2)O(4) (SG- B b21m) at 1100 degrees C. The estimated band gap, as determined by UV-Vis diffuse

P. H. Borse; C. R. Cho; K. T. Lim; Y. J. Lee; T. E. Hong; J. S. Bae; E. D. Jeong; H. J. Kim; H. G. Kim

2011-01-01

350

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.

351

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

352

THE WATER CYCLE/ CLOUDS  

NSDL National Science Digital Library

Students will learn about the water cycle and how it works. You will explore many resources to find out many new factors about the water cycle. What is the water cycle? National water cycle Name the 4 water parts of the water cycle? Weather wonders Where are 3 places that the water cycle exists- What happens after condensation? animated water cycle Name 4 types of clouds? What is the highest level cloud called? Which cloud is associated with powerful thunderstorms? Cloud Types What do clouds have to do with the water cycle? National water cycle What is ...

Ms.brown

2009-04-06

353

Smart Water: Energy-Water Optimization in Drinking Water Systems  

EPA Science Inventory

This project aims to develop and commercialize a Smart Water Platform â?? 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...

354

Hydrogen-treated TiO2 nanowire arrays for photoelectrochemical water splitting.  

PubMed

We report the first demonstration of hydrogen treatment as a simple and effective strategy to fundamentally improve the performance of TiO(2) nanowires for photoelectrochemical (PEC) water splitting. Hydrogen-treated rutile TiO(2) (H:TiO(2)) nanowires were prepared by annealing the pristine TiO(2) nanowires in hydrogen atmosphere at various temperatures in a range of 200-550 °C. In comparison to pristine TiO(2) nanowires, H:TiO(2) samples show substantially enhanced photocurrent in the entire potential window. More importantly, H:TiO(2) samples have exceptionally low photocurrent saturation potentials of -0.6 V vs Ag/AgCl (0.4 V vs RHE), indicating very efficient charge separation and transportation. The optimized H:TiO(2) nanowire sample yields a photocurrent density of ?1.97 mA/cm(2) at -0.6 V vs Ag/AgCl, in 1 M NaOH solution under the illumination of simulated solar light (100 mW/cm(2) from 150 W xenon lamp coupled with an AM 1.5G filter). This photocurrent density corresponds to a solar-to-hydrogen (STH) efficiency of ?1.63%. After eliminating the discrepancy between the irradiance of the xenon lamp and solar light, by integrating the incident-photon-to-current-conversion efficiency (IPCE) spectrum of the H:TiO(2) nanowire sample with a standard AM 1.5G solar spectrum, the STH efficiency is calculated to be ?1.1%, which is the best value for a TiO(2) photoanode. IPCE analyses confirm the photocurrent enhancement is mainly due to the improved photoactivity of TiO(2) in the UV region. Hydrogen treatment increases the donor density of TiO(2) nanowires by 3 orders of magnitudes, via creating a high density of oxygen vacancies that serve as electron donors. Similar enhancements in photocurrent were also observed in anatase H:TiO(2) nanotubes. The capability of making highly photoactive H:TiO(2) nanowires and nanotubes opens up new opportunities in various areas, including PEC water splitting, dye-sensitized solar cells, and photocatalysis. PMID:21710974

Wang, Gongming; Wang, Hanyu; Ling, Yichuan; Tang, Yuechao; Yang, Xunyu; Fitzmorris, Robert C; Wang, Changchun; Zhang, Jin Z; Li, Yat

2011-06-28

355

WATER REQUIREMENTS OF LIVESTOCK  

Microsoft Academic Search

Providing enough quality water is essential for good livestock husbandry. Water makes up 80% of the blood, regulates body temperature and is vital for organ functions such as digestion, waste removal and the absorption of nutrients. Understanding daily livestock watering needs is key when designing a livestock watering system. The daily water requirement of livestock varies significantly among animal species.

D. Ward; K. McKague

356

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.

357

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

358

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

359

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.

360

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

361

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,

362

Drought and Water Allocation  

NSDL National Science Digital Library

The US Department of Agriculture's Water Quality Information Center at the National Agricultural Library has placed a new database online. The Drought and Water Allocation bibliography includes "71 articles on water allocation as it relates to drought and water shortages dated 1992-1999. Competition for water resources, legal rights and remedies, and economic options are highlighted."

363

Water Resources Data - Wisconsin, Water Year 2003  

USGS Publications Warehouse

Water-resources data for the 2003 water year for Wisconsin include records of streamflow at gaging stations, partialrecord stations, and miscellaneous sites, records of precipitation, and records of chemical, biological, and physical characteristics of surface water. In addition, water levels in observation wells are reported. These data were collected by the U.S. Geological Survey in cooperation with State and local agencies and other Federal agencies in Wisconsin.

Waschbusch, R. J.; Olson, D. L.; Ellefson, B. R.; Stark, P. A.

2004-01-01

364

Water Resources Data - Wisconsin, Water Year 2002  

USGS Publications Warehouse

Water-resources data for the 2002 water year for Wisconsin include records of streamflow at gaging stations, partial record stations, and miscellaneous sites, records of precipitation, and records of chemical, biological, and physical characteristics of surface water. In addition, water levels in observation wells are reported. These data were collected by the U.S. Geological Survey in cooperation with State and local agencies and other Federal agencies in Wisconsin.

Waschbusch, R. J.; Olson, D. L.; Ellefson, B. R.; Stark P. A.

2003-01-01

365

Industrial Water Reuse Versus Net Water Loss.  

National Technical Information Service (NTIS)

Water use and other data of 13 Delaware River Basin industrial plants were examined to determine the impact of increased reuse of water upon consumptive use of water. The plants were of the petroleum, chemical, paper, food, and primary metal industries. T...

S. D. Selzer P. J. Webber

1983-01-01

366

Clear salt water versus clear pure water  

NSDL National Science Digital Library

A controlled experiment allows an investigator to conduct the experiment by changing only one single factor while keeping all other variables constant. The factor that was changed in this experiment, called the independent variable, was the type of water used: pure water or salt water.

Nancy Pelaez (Purdue University;Biological Sciences)

2007-08-17

367

Water research: solving colorado's water problems  

Microsoft Academic Search

Several projects conducted by the Colorado Water Resources Research Institute are outlined. The report includes descriptive photographs and simplified procedural explanations designed for use by the general public. Sections of the report include: (1) high country irrigation reservoirs; (2) Colorado's economy - the role of water; (3) answering the flood control benefit question; (4) solving high country water and sewer

1977-01-01

368

Where's the Water?  

NSDL National Science Digital Library

In this lesson, the students will conduct an investigation to purify water. Students will engineer a method for cleaning water, discover the most effective way to filter water, and practice conducting a scientific experiment.

Adventure Engineering

369

Total Water Management.  

National Technical Information Service (NTIS)

There is a growing need for urban water managers to take a more holistic view of their water resource systems as population growth, urbanization, and current o perations put different stresses on the environment and urban infrastructure. Total Water Manag...

A. Cannan D. Rodrigo E. J. L. Calva L. Roesner

2012-01-01

370

Fluoride Determinations in Water.  

National Technical Information Service (NTIS)

The report is a manual for a course designed to provide water fluoride analysis training for individuals directly involved in performing fluoride determinations on drinking waters. The contents include health and engineering aspects of water fluoridation,...

1971-01-01

371

Aging Water Infrastructure  

EPA Science Inventory

The Aging Water Infrastructure (AWI) research program is part of EPAâ??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...

372

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.

373

Selecting a new water heater.  

National Technical Information Service (NTIS)

This fact sheet describes the types of water heaters available (storage water heaters, demand water heaters, heat pump water heaters, tankless coil and indirect water heaters, and solar water heaters). The criteria for selection are discussed. These are c...

1995-01-01

374

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.

Addison, Keith

2010-01-01

375

Geothermal hot water system  

SciTech Connect

Geothermal hot water system including a hot water tank and a warm water tank which are heated independently of each other by a close loop freon system. The closed loop freon system includes a main condenser which heats water for the warm water tank and a super-heated condenser which heats water for the hot water tank, and where the freon passes through a water evaporator which is heated by water such as from a well or other suitable source. The water evaporator in the closed loop freon system passes the water through but no environmental change to the water. An electrical circuit including aquastats in the warm water tank connected therethrough controls operation of the closed loop freon system including respective pumps on the super-heated condenser and main condenser for pumping water. Pumps pump water through the main condenser for the warm tank and through the super-heated condenser for the hot tank. The system provides for energy conservation in that the head pressure of the compressor is kept in the lower operating ranges as determined by the discharge flow of the main condenser which varies by the head pressure and temperature flow control which varies by temperature. The geothermal hot water system uses a least amount of energy in heating the water in the hot tank as well as the warm tank.

Dittell, E.W.

1983-05-10

376

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

377

Mineralization enhancement of a recalcitrant pharmaceutical pollutant in water by advanced oxidation hybrid processes  

Microsoft Academic Search

Degradation of the biorecalcitrant pharmaceutical micropollutant ibuprofen (IBP) was carried out by means of several advanced oxidation hybrid configurations. TiO2 photocatalysis, photo-Fenton and sonolysis – all of them under solar simulated illumination – were tested in the hybrid systems: sonophoto-Fenton (FS), sonophotocatalysis (TS) and TiO2\\/Fe2+\\/sonolysis (TFS). In the case of the sonophoto-Fenton process, the IBP degradation (95%) and mineralization (60%)

F. Méndez-Arriaga; R. A. Torres-Palma; C. Pétrier; S. Esplugas; J. Gimenez; C. Pulgarin

2009-01-01

378

Photocatalytic Degradation of Diethyl Phthalate (DEP) in Water Using TiO 2  

Microsoft Academic Search

The degradation of diethyl phthalate (DEP) in aqueous solution by titanium dioxide (TiO2) photocatalysis has been investigated in our research. DEP was completely removed in the solution by 50-min irradiation.\\u000a Results show that DEP degradation rate was affected by initial DEP concentration, photocatalyst amount, light intensity, and\\u000a pH. Photocatalytic degradation intermediates were identified by gas chromatography-mass spectrometry intermediates were identified

Wen-Bin Huang; Chih-Yu Chen

2010-01-01

379

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

NASA Astrophysics Data System (ADS)

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.

Glasser, L.

2004-03-01

380

Water footprint of Ghana  

NASA Astrophysics Data System (ADS)

Water is used in almost all human endeavour. Unlike oil, water does not have a substitute. There are many factors that affect the water consumption pattern of people. These include climatic condition, income level and agricultural practices among others. The water footprint concept has been developed in order to have an indicator of water use in relation to its consumption by people. The water footprint of a country is defined as the volume of water needed for the production of the goods and services consumed by the inhabitants of the country (Chapagain and Hoekstra, 2008). Due to the bulky nature of water, it is not in its raw state a tradable commodity though it could be traded through the exchange of goods and services from one point to the other. Closely linked to the water footprint concept is the virtual water concept. Virtual water can be defined as the volume of water required to produce a commodity or service (Chapagain and Hoekstra, 2008 and Allan, 1999). The international trade of these commodities implies flows of virtual water over large distances. The water footprint of a nation can therefore be assessed by quantifying the use of domestic water resources, taking out the virtual water flow that leaves the country and adding the virtual water flow that enters the country to it. This research focuses on the assessment and analysis of the water footprints of Ghana considering only the consumptive component of the water footprint. In addition to livestock, 13 crops were considered, 4 of which were cash crops. Data was analysed for the year 2001 to 2005 The most recent framework for the analysis of water footprint is offered by Chapagain and Hoekstra. This was adopted for the study. The water footprint calculations show that the water footprint of Ghana is about 20011 Gm³/yr. Base on this the average water footprint of a Ghanaian is 823 m³/cap/yr. Not only agricultural crops but also other products require water for their manufacture, aluminium being a case in point. The water required for energy production through hydropower is important to account for, as well as the question to what extent this may or may not be considered non-consumptive water use. Further research is needed to correctly estimate the water footprint of energy-intensive products. Keywords: water footprint, virtual water, trade, commodity

Debrah, E. R.; Odai, S. N.; Annor, F. O.; Adjei, K. A.; van der Zaag, P.

2009-04-01

381

Pricing China's irrigation water  

Microsoft Academic Search

Many development agencies and other actors are advocating that China adopt a system of water markets or of high water prices in order to resolve the inefficiencies of irrigation agriculture and to supply sufficient water for growing urban and industrial uses. We argue that this proposal rests on a series of propositions: that the price of water is too low

Michael Webber; Jon Barnett; Brian Finlayson; Mark Wang

2008-01-01

382

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.

Association, National G.

383

The Water Cycle  

NSDL National Science Digital Library

Today you will explore the water cycle. Please visit the following websites (in order!) to gather information about the water cycle. Fill out your Information Sheet as you go. 1. Water cycle story 2. Water Cycle--heat 3. animation (Make sure to read the captions at the bottom!) ...

Hauck, Mrs.

2006-08-26

384

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.

385

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

386

Bottled Water and Fluoride  

MedlinePLUS

... doesn't the EPA have jurisdiction over the quality of bottled water since it regulates drinking water? What FDA regulations ... doesn't the EPA have jurisdiction over the quality of bottled water since it regulates drinking water? The Environmental Protection ...

387

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

388

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

389

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

390

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.

Museum, Chicago C.

2008-01-01

391

Household hot water systems  

Microsoft Academic Search

An arrangement for combination with the conventional hot water system of a house or building in which the water is conventionally heated and stored in a tank, the arrangement comprising a solar energy panel (at an upper level) with a thermostatic valve and a supplementary cold water tank, connected into the system in such a way that hot water is

Tacchi

1983-01-01

392

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

393

WIND WATER PUMPING  

Technology Transfer Automated Retrieval System (TEKTRAN)

Wind power has been used to pump water for centuries; however, the development of the modern wind turbine has allowed for more applications for water pumping. This book was written to give a complete overview of wind power water pumping and serve as a design guide for water pumping systems. The bo...

394

Energy---Water Interdependence  

Microsoft Academic Search

ABSTRACT Energy and water security and sustainability have become a national and global priority. The continued security and economic health of any country depends on a sustainable supply of both energy and water because these two critical natural resources are inexorably linked. The production of energy requires large volumes of water while the treatment and distribution of water is equally

E. H. Moran; J. A. Tindall; A. A. Campbell

2010-01-01

395

The Amazing Water Trick  

NSDL National Science Digital Library

Using two baby food jars, food coloring, and an index card, you'll 'marry' the jars to see how hot water and cold water mix. Besides illuminating the cool fact that an index card can act as a lid (with no water gushing out), this activity also teaches about the differing densities of hot and cold water.

Murphy, Pat; Klages, Ellen; Shore, Linda

1998-01-01

396

Solar hot water heater  

Microsoft Academic Search

A solar hot water heater includes an insulated box having one or more hot water storage tanks contained inside and further having a lid which may be opened to permit solar radiation to heat a supply of water contained within the one or more hot water storage tanks. A heat-actuated control unit is mounted on an external portion of the

1982-01-01

397

Water storage tank  

Microsoft Academic Search

The present invention relates to a cylindrical water storage tank for a solar water heater which tank is entirely surrounded by a layer of insulating material, said cylindrical tank being arranged to be horizontally disposed in use and having water outlet means in an upper region thereof and water inlet means in a lower region thereof, wherein the portion of

Riley

1983-01-01

398

Water Cycle Animation  

NSDL National Science Digital Library

The water cycle is Earth's natural mechanism for transporting and recycling water between the surface and the atmosphere. Through the processes of condensation, precipitation, infiltration, runoff, transpiration, and evaporation, water continuously travels from the atmosphere to the ground and back again. In this animation from NASA, users can observe the steps of the water cycle. The segment is fifty-two seconds in length.

399

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.

400

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

401

Water Recycling in Lactation  

Microsoft Academic Search

During lactation, female rodents, dingoes, and kangaroos consume urine and feces excreted by the young. Studies with tritiated water as a tracer for native water showed that roughly one-third of the water secreted as milk was returned to the mother. The results are cogent to studies of water balance of lactation and to current methods used for estimating milk production.

P. Baverstock; B. Green

1975-01-01

402

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

403

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

404

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.

405

Colorado Water Knowledge  

NSDL National Science Digital Library

The Colorado Water Knowledge Web site is maintained by the Colorado State University Colorado Water Resources Research Institute. The site allows kids to explore all aspects of water science including general facts, a description of the water cycle, stream processes, Colorado geology and water history, major aquifers of the area, aquatic life in local waters, Colorado water laws and regulations, and much more. Although it isn't graphic intensive, the site does a good job of explaining the wide array of concepts using simple descriptions, lists of facts, and a few choice illustrations. [JAB

406

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.

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

2006-01-01

407

Photochemical and thermal hydrogen production from water catalyzed by carboxylate-bridged dirhodium(II) complexes.  

PubMed

A series of dinuclear Rh(II) complexes, [Rh(2)(?-OAc)(4)(H(2)O)(2)] (HOAc = acetic acid) (1), [Rh(2)(?-gly)(4)(H(2)O)(2)] (Hgly = glycolic acid) (2), [Rh(2)(?-CF(3)CO(2))(4)(acetone)(2)] (3), and [Rh(2)(bpy)(2)(?-OAc)(2)(OAc)(2)] (4), were found to serve as H(2)-evolving catalysts in a three-component system consisting of tris(2,2'-bipyridine)ruthenium(II) (Ru(bpy)(3)(2+)), methylviologen (MV(2+)), and ethylenediaminetetraacetic acid disodium salt (EDTA). It was also confirmed that thermal reduction of water into H(2) by MV(+)?, in situ generated by the bulk electrolysis of MV(2+), is effectively promoted by 1 as a H(2)-evolving catalyst. The absorption spectra of the photolysis solution during the photocatalysis were monitored up to 6 h to reveal that the formation of photochemical or thermal byproducts of MV(+)? is dramatically retarded in the presence of the Rh(II)(2) catalysts, for the H(2) formation rather than the decomposition of MV(+)? becomes predominant in the presence of the Rh(II)(2) catalysts. The stability of the Rh(II)(2) dimers was confirmed by absorption spectroscopy, (1)H NMR, and ESI-TOF mass spectroscopy. The results indicated that neither elimination nor replacement of the equatorial ligands take place during the photolysis, revealing that one of the axial sites of the Rh(2) core is responsible for the hydrogenic activation. The quenching of Ru*(bpy)(3)(2+) by 1 was also investigated by luminescence spectroscopy. The rate of H(2) evolution was found to decrease upon increasing the concentration of 1, indicating that the quenching of Ru*(bpy)(3)(2+) by the Rh(ii)(2) species rather than by MV(2+) becomes predominant at the higher concentrations of 1. The DFT calculations were carried out for several possible reaction paths proposed (e.g., [Rh(II)(2)(?-OAc)(4)(H(2)O)] + H(+) and [Rh(II)(2)(?-OAc)(4)(H(2)O)] + H(+) + e(-)). It is suggested that the initial step is a proton-coupled electron transfer (PCET) to the Rh(II)(2) dimer leading to the formation of a Rh(II)Rh(III)-H intermediate. The H(2) evolution step is suggested to proceed either via the transfer of another set of H(+) and e(-) to the Rh(II)Rh(III)-H intermediate or via the homolytic radical coupling through the interaction of two Rh(II)Rh(III)-H intermediates. PMID:20976343

Tanaka, Saya; Masaoka, Shigeyuki; Yamauchi, Kosei; Annaka, Masahiko; Sakai, Ken

2010-10-25

408

Organic substances in water  

USGS Publications Warehouse

This is the third of several compilations of briefing papers on water quality by the U.S. Geological Survey. Each briefing paper is prepared in a simple, nontechnical, easy-to-understand manner. This U.S. Geological Survey Circular contains papers on selected organic substances in water. Briefing papers are included on ' Why study organic substances in water. ', ' Taste and odor in water ', and ' Classification and fractionation of organic solutes in natural waters'. (USGS)

Edited by Greeson, Phillip E.

1981-01-01

409

Avoid water hammer  

SciTech Connect

Discusses where water hammer occurs, effects of water hammer, and conditions causing water hammer (hydraulic shock, thermal shock, differential shock). Points out that even mild water hammer can weaken and eventually destroy piping, gauges, floats, heat exchange equipment, etc. Suggests that greater understanding of water hammer should help introduce more preventive measures into system designs and installations, which will help provide maximum safety for personnel, lower maintenance cost and reduce system downtime.

Kremers, J.

1983-03-01

410

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.

411

[Recovered water mineralization technique].  

PubMed

The possibility to mineralize water by metering out concentrated salt solutions in the amounts necessary to bring it to within the potable water standards with intermediate exchange of chlorine ions for bicarbonate-ions has been demonstrated. The proposed technique ensures physiological quality and stability of recovered water mineralized with solutions of inorganic salts. Stability of concentrated salt solutions kept in metering syringes and potable water was evaluated. Organoleptic tests of resultant potable water were conducted. PMID:11840873

Skliar, E F; Amiragov, M S; Berezkin, S V; Kurochkin, M G; Skuratov, V M

2001-01-01

412

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 such as evapotranspiration, and water storage. 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.

413

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.

Association, National G.

414

The Water Cycle  

NSDL National Science Digital Library

Students will work with interactive internet resources to learn all about the water cycle. Fourth Grade Science Standard 1 Objective 2: Describe the water cycle. Locate examples of evaporation and condensation in the water cycle (e.g., water evaporates when heated and clouds or dew forms when vapor is cooled). Describe the processes of evaporation, condensation, and precipitation as they relate to the water cycle. Identify locations that hold water as it passes through the water cycle (e.g., oceans, atmosphere, fresh surface water, snow, ice, and ground water). Construct a model or diagram to show how water continuously moves through the water cycle over time. Describe how the water cycle relates to the water supply in your community. Web Quest Links Introduction Task Resources Evaluation Conclusion Teacher Guide Introduction Have you ever wondered how water gets from oceans, lakes, streams, or clouds into your glass? Check out the following links to learn more about it! TASK Start out by learning the concepts in this song from Bill Nye! Bill Nye the Science Guy- Water Cycle Jump Look ...

Lish, Ms.

2009-04-06

415

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.

416

Price of Water  

NASA Astrophysics Data System (ADS)

There are watercourses on the globe which as yet do not deliver up their energy to the needs of the people. How much energy their waters bear, is it worth to take away this energy? Those and alike questions must be (and they are) answered before start to build hydro power station. Similar problems must be solved to control hydro power plants in most gainful way which is known as hydrothermal coordination. The notion of price of water can be met lately in technical literature as one of numerical indices of these issues. The gross price of water and net price of water are considered in this paper. Gross price of 1 t water is the price of electric energy obtained by conversion of potential energy of 1 t of water, lifted to a height of power station water head. Net price of water is the difference between gross price and total expenses determined by hydro power station building and its exploitation costs in a year related to 1 m3 of water. If net price of water is positive, it is worth building power station. The greater net price is, the more urgent is the building. Net price of water grows with water head but it continues only to some height of the dam because further increase of head sharply increases capital outlay and other exploitation expenses. To maximize net price of water, optimization of net price function can be done. Net price of water diminishes when some amount of water is diverted for other needs. When amount of diverted water is out of discussion, no controversy can emerge. However when by diverted water some goods with some monetary worth can be obtained, the task must be solved how much water can be diverted so that the water of watercourse be used to the maximum benefit. The environmental issues must be taken into account as well.

Survilo, Josifs; Boreiko, Dmitrijs

2009-01-01

417

Water recovery in space.  

PubMed

In the absence of recycling, water represents over 90% of the life-support consumables for a manned spacecraft. In addition, over 90% of the waste water generated can be classified as moderately or slightly contaminated (e.g. shower water, condensate from the air-conditioning system, etc.). The ability to recover potable water from moderately contaminated waste water hence enables significant savings to be made in resupply costs. A development model of such a water-recovery system, based on membrane technology has been produced and tested using "real waste water" based on used shower water Results indicate some 95% recovery of potable water meeting ESA standards, with total elimination of microbial contaminants such as bacteria, spores and viruses. PMID:11725802

Tamponnet, C; Savage, C J; Amblard, P; Lasserre, J C; Personne, J C; Germain, J C

1999-03-01

418

World Water Council  

NSDL National Science Digital Library

In 1997, the World Water Council had its first official forum in Marrakech, and since then they have continued their work on "critical water issues at all levels." Some of these issues include efficient water conservation, water use management, and other relevant matters. With its compelling visual images and design, the homepage contains sections that provide information on upcoming World Water Forums and some very helpful overviews of their work. One such general overview may be found in the "Water at a Glance" area, which provides information on the nature of freshwater resources around the globe. Persons involved in water policy and international affairs may wish to look over their online library, which includes their annual reports, synopses of materials covered in the Water Forum meetings, and papers such as "The Right to Water: From Concept To Implementation." It is also worth noting that many of the materials on the site are available in French and Spanish.

419

Sustaining Waters: From Hydrology to Drinking Water  

Microsoft Academic Search

Around the world, disastrous effects of floods and droughts are painful evidence of our continuing struggle between human resource demands and the sustainability of our hydrologic systems. Too much or too little rainfall is often deemed the culprit in these water crises, focussing on water \\

S. Toch

2003-01-01

420

Water Health Series: Bottled Water Basic, 2005.  

National Technical Information Service (NTIS)

Bottled water is the fastest growing drink choice in the United States, and Americans spend billions of dollars each year to buy it. Some people drink bottled water as an alternative to other beverages; others drink it because they prefer its taste or thi...

2005-01-01

421

Water-Borne Illnesses. Water in Africa.  

ERIC Educational Resources Information Center

|The Water in Africa Project was realized over a 2-year period by a team of Peace Corps volunteers. As part of an expanded, detailed design, resources were collected from over 90 volunteers serving in African countries, photos and stories were prepared, and standards-based learning units were created for K-12 students. This unit, "Water-Borne…

Garrett, Carly Sporer

422

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...

423

Urban Water Runoff and Water Quality Control.  

National Technical Information Service (NTIS)

The 1972 Amendments to FWPCA specifically require that non-point sources of water pollution be considered in the development of water quality management plans for both local and areawide planning. Urban runoff often accounts for a major portion of the non...

J. T. Wildrick K. Kuhn W. R. Kerns

1976-01-01

424

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

425

Water Is All around You.  

ERIC Educational Resources Information Center

|Introduces an activity on water that encourages students to learn about water use and conservation. Focuses on the ways in which water is used in homes, the water cycle, and water conservation. (YDS)|

Smith, Michael J.; Southard, John B.

2002-01-01

426

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

427

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

428

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.

429

International Water Association  

NSDL National Science Digital Library

A worldwide organization of water professionals, the International Water Association's (IWA) Web site illustrates its commitment "to help water professionals create innovative, pragmatic, and sustainable solutions to challenging global water needs." Visitors can discover IWA's many activities from conferences and forums to task forces. Researchers can discover the various IWS groups that specialize in topics including Source Management, Education, Health, Management Training, and Water Quality Management. Although many of the publications are restricted to members, educators and students can read reports from the Sustainability in Water Sector and abstracts from IWA journals.

2003-01-01

430

Geothermal livestock waterer  

SciTech Connect

A livestock waterer is described which is automatically heated through use of geothermal energy within the earth. Working fluid is housed within a reservoir below the surface of the earth, is heated to evaporation by geothermal heat, is transferred to a condensation chamber adjacent a water container, whereupon condensation of said working fluid occurs transferring heat to the water within the water container. Condensed working fluid is returned to the reservoir. An insulating lid is shown which allows demand use of the waterer by livestock and aids in the retention of heat within the water supply.

Streed, C.P.

1982-03-23

431

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.

432

33 CFR 2.36 - Navigable waters of the United States, navigable waters, and territorial waters.  

Code of Federal Regulations, 2013 CFR

33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Navigable waters of the United States, navigable waters, and territorial waters. 2.36 Section 2.36 Navigation and Navigable Waters COAST...

2013-07-01

433

A Comparison of Water Quality Indices for Coastal Water  

Microsoft Academic Search

The present article discusses and compares five different water quality indices, viz arithmetic water quality index, multiplicative water quality index, unweighted arithmetic water quality index, unweighted multiplicative water quality index, and Harkin's water quality index, which were considered for characterizing the coastal water quality at the Jawaharlal Nehru Port Trust, Bombay, India. Dissolved oxygen, pH, biochemical oxygen demand (BOD), temperature,

A. K. Gupta; S. K. Gupta; Rashmi S. Patil

2003-01-01

434

Water Resources Data for Connecticut, Water Year 1983.  

National Technical Information Service (NTIS)

Water Resources Data for the 1983 water year for Connecticut 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 wells. This v...

C. E. Thomas L. A. Weiss I. S. Gasperini J. W. Bingham

1985-01-01

435

Cooperative water resource allocation based on equitable water rights  

Microsoft Academic Search

A comprehensive methodology is developed to achieve equitable, efficient and sustainable water allocation in a river basin. Water allocation is carried out in two steps: (1) allocation of initial water rights to water stakeholders and users based on existing water rights systems or agreements; and (2) reallocation of water and net benefits through water transfers to promote equitable cooperation of

Lizhong Wang; Liping Fang; Keith W. Hipel

2003-01-01

436

Water Purification Systems.  

National Technical Information Service (NTIS)

Clearwater Pool Technologies employs NASA-developed silver/copper ionization to purify turtle and dolphin tanks, cooling towers, spas, water recycling systems, etc. The pool purifier consists of a microcomputer to monitor water conditions, a pair of metal...

1994-01-01

437

Water in the Mantle  

NSDL National Science Digital Library

This schematic shows a cross-section of the planet and how water can migrate through the deep interior of the Earth. Blue arrows indicate a movement of water downward, yellow arrows indicated movement towards the surface.

Ohtani, E.; First published in Elements[2005], reproduced by COMPRES Image Library

438

Healthy Water, Healthy People.  

ERIC Educational Resources Information Center

Describes a hands-on activity, Hitting the Mark, which is found in the "Healthy Water, Healthy People Water Quality Educators Guide" in terms of its objectives, materials, background, procedures, activities, and assessment. (KHR)

Etgen, John

2002-01-01

439

It's Your Drinking Water  

MedlinePLUS

... sources: Consumer Confidence Report: Starting in 1999, these water quality reports will be prepared annually by each community ... first consumer confidence report (also called a drinking water quality report) available to the public. Beginning in 2000, ...

440

Radon in Drinking Water  

MedlinePLUS

... for reducing radon health risks in both drinking water and indoor air quality, a unique multimedia framework authorized in the 1996 Amendments to the Safewater Drinking Water Act (SDWA). Information about the proposed rule and ...

441

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.

Doherty, Paul

2000-01-01

442

Project Weather and Water.  

ERIC Educational Resources Information Center

Introduces Project Weather and Water with the goal of developing and testing ideas of how to implement weather topics and water physics in an integrated way. Discusses teacher preparation, implementation, and evaluation of this project. (ASK)

Hansen, Pal J. Kirkeby

2000-01-01

443

Water Bank Program.  

National Technical Information Service (NTIS)

The Water Bank Program provides incentive payments to landowners and operators for conserving waters, preserving or improving migratory waterfowl habitat and other wildlife resources. The program will help in reducing the loss of wetlands in the Nation. T...

1972-01-01

444

Healthy Water, Healthy People.  

ERIC Educational Resources Information Center

|Describes a hands-on activity, Hitting the Mark, which is found in the "Healthy Water, Healthy People Water Quality Educators Guide" in terms of its objectives, materials, background, procedures, activities, and assessment. (KHR)|

Etgen, John

2002-01-01

445

A Simple Water Channel  

ERIC Educational Resources Information Center

Describes a simple water channel, for use with an overhead projector. It is run from a water tap and may be used for flow visualization experiments, including the effect of streamlining and elementary building aerodynamics. (MLH)

White, A. S.

1976-01-01

446

About Body Water  

MedlinePLUS

... being able to drink enough fluids. Mineral salts (electrolytes), such as sodium and potassium, are dissolved in the water in the body. Water balance and electrolyte balance (see Electrolyte Balance ) are closely linked. The ...

447

Water and bioenergy  

NASA Astrophysics Data System (ADS)

Water management expert Arjen Hoekstra, together with environmental science and energy specialists, has analysed the impact of increasing the use of biofuels in the transport sector on global water demand.

2012-07-01

448

GROUND WATER SAMPLING ISSUES  

EPA Science Inventory

Obtaining representative ground water samples is important for site assessment and remedial performance monitoring objectives. Issues which must be considered prior to initiating a ground-water monitoring program include defining monitoring goals and objectives, sampling point...

449

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.

Foundation, Wgbh E.

2005-12-17

450

Water Safety Lesson  

NSDL National Science Digital Library

Through role-playing and teacher presentation, students learn how to be safe around water. Students learn the three most important safety rules, ways to rescue someone from the water, boat safety, and ocean safety considerations.

Diego, The C.

2010-04-12

451

Water Disinfection Practice.  

National Technical Information Service (NTIS)

The current review of canteen water disinfection proceeded along three general lines. A summary has been prepared of the information available from the literature on canteen water disinfection. The current opinions of two outstanding investigators in the ...

J. T. O'Connor

1968-01-01

452

Water Entry System.  

National Technical Information Service (NTIS)

The present invention relates to water entry of unmanned underwater vehicles and more specifically to suppression of cavity formation upon entry of such vehicles into the water. Underwater vehicles, such as torpedoes, are generally designed for speed, rel...

R. Kuklinski

2009-01-01

453

A Simple Water Channel  

ERIC Educational Resources Information Center

|Describes a simple water channel, for use with an overhead projector. It is run from a water tap and may be used for flow visualization experiments, including the effect of streamlining and elementary building aerodynamics. (MLH)|

White, A. S.

1976-01-01

454

Private Drinking Water Wells  

NSDL National Science Digital Library

This site, created by the Environmental Protection Agency, contains information from the on testing and protecting private water sources. The site can be helpful for persons having a private well or simply those interested in water science.

2008-10-06

455

HANDBOOK: GROUND WATER  

EPA Science Inventory

This document is provides information on ground-water contamination control and prevention technology to decision makers, field managers, and the scientific community. his 212-page resource document brings together available technical information on ground water in a convenient f...

456

Water-based Screenprinting.  

ERIC Educational Resources Information Center

Outlines the techniques for silkscreening using water-based inks, concentrating on the qualities of water-based printing that differ from oil-based printing. Includes a step-by-step description of the process illustrated with photographs. (LS)

Kreneck, Lynwood

1989-01-01

457

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

458

Clean Water and Oceans: Water Pollution  

NSDL National Science Digital Library

This is the water pollution portal for the Natural Resources Defense Council (NRDC). NRDC works to continue reductions in industrial water pollution while pressing for effective pollution controls on agriculture, logging and other sources previously exempt from them. They help develop and promote strong federal laws and regulations to address polluted runoff, raw sewage discharges, and factory farm wastes and to sue polluters when the Clean Water Act is violated. This site contains simple issue overviews, news, how-to guides, frequently asked questions, photo essays and more in a section called In Brief. The In Depth section offers reports, white papers, policy analyses and other materials by NRDCs lawyers, scientists and analysts.

459

Water Resources Research supports water economics submissions  

NASA Astrophysics Data System (ADS)

AGU's international interdisciplinary journal Water Resources Research (WRR) publishes original contributions in hydrology; the physical, chemical, and biological sciences; and the social and policy sciences, including economics, systems analysis, sociology, and law. With the rising relevance of water economics and related social sciences, the editors of WRR continue to encourage submissions on economics and policy. WRR was originally founded in the mid 1960s by Walter Langbein and economist Allen Kneese. Several former WRR editors have been economists—including David Brookshire, Ron Cummings, and Chuck Howe—and many landmark articles in water economics have been published in WRR.

Griffin, Ronald C.

2012-09-01

460

Water crisis in Palestine  

Microsoft Academic Search

Palestine is experiencing a severe water crisis caused mainly by the lack of control over the Palestinian water resources. At present the average per capita water consumption by the Palestinian population is approximately 55 l\\/c\\/d, or 55% of the WHO minimum standard of 100 l\\/c\\/d. The above statements show that the communal water supply for the Palestinian population is substantially

Bader Ali Ahmad Abu Zahra

2001-01-01

461

The World's Water  

NSDL National Science Digital Library

Supplemental to The World's Water book by Peter Gleick, this site offers data on the world's freshwater resources and uses. Tables and maps provide information on quantity and quality issues including data on access to safe drinking water; waterborne disease outbreaks; desalination capacity; as well as hydroelectric capacity and production. There is also a unique chronology documenting the historical connections between human conflict and water. Additionally there is an expansive list of links to water-relevant agencies and organizations.

2001-08-13

462

Water Privatization in Spain  

Microsoft Academic Search

Water management in Spain is submitted to a non?uniform geographical and seasonal distribution of water resources. The non?uniform distribution of resources is worsened by the non?uniform allocation of demand (mainly irrigation and urban). Because that, water supply, aquifers, and wetlands are driven to a high risk. Even though, there are examples of good water management, as is shown for the

Manuel A. Soler Manuel

2003-01-01

463

THE WATER CYCLE  

NSDL National Science Digital Library

DESK Standard: Understand the processes of evaporation, condensation, and precipitation as they relate to the water cycle. Water Cycle Diagram DATES: You can begin this activity on October 16. You should complete it by October 20. OBJECTIVE: You have been learning about the water cycle in class. This activity gives you the chance to review some important vocabulary: evaporation condensation precipitation collection You will watch a short video and complete a water ...

Hughes, Mr.

2006-02-18

464

Water: Clearly Unique!  

NSDL National Science Digital Library

In this activity on page 4 of the PDF, learners conduct some quick and easy tests to determine the differences between water and other liquids that look very similar to water. Learners compare how water, rubbing alcohol, and mineral oil repel, absorb, and evaporate.

Society, American C.

2011-01-01

465

Water chlorination Vol. 5  

Microsoft Academic Search

This book describes the significant original contributions in the field of water chlorination of the last three years. It includes chlorination research, developments and alternatives. Issues covered include: water chlorination; risk; epidemiology; carcinogenic and mutagenic effects; toxicology of disinfectants; aquatic models and tumor induction; environmental effects; disinfection; reaction dynamics; chemical methods; drinking water treatment and wastewater treatment.

R. L. Jolley; R. J. Bull; W. P. Davis; S. Katz; M. H. Roberts

1985-01-01

466

Innovations in Water Management  

Microsoft Academic Search

The water allocations made to the lower Colorado River Basin under the 1922 Colorado River Compact. as well as the later contractual allocations made by the Secretary of the Interior under the Boulder Canyon Project Act to the States of Arizona, California, and Nevada, and water agencies in those states, were based on significant overestimates offuture water supply. Based on

Jerome C. Muys

2000-01-01

467

Water Resource Adaptation Program  

EPA Science Inventory

The Water Resource Adaptation Program (WRAP) contributes to the U.S. Environmental Protection Agency?s (U.S. EPA) efforts to provide water resource managers and decision makers with the tools needed to adapt water resources to demographic and economic development, and future clim...

468

Water Conservation Resource List.  

ERIC Educational Resources Information Center

Alarmed by the growing water shortage, the New Jersey State Office of Dissemination has prepared this annotated list of free or inexpensive instructional materials for teaching about water conservation, K-l2. A tipsheet for home water conservation is appended. (Editor/SJL)

NJEA Review, 1981

1981-01-01

469

Water Conservation in Oman  

Microsoft Academic Search

Limited resources and growing needs for water have triggered a nationwide campaign for water conservation in the Sultanate of Oman. A land and soil survey study of Oman shows the availability of more arable land than present water resources could support. Groundwater is the main source for agricultural production. Overpumping at rates higher than the natural recharge has resulted in

Hayder A. Abdel-Rahman; Isam Mohammed Abdel-Magid

1993-01-01

470

LIGHT WATER ANALYSER  

Microsoft Academic Search

A monitoring system for indicating the heavy water content of air is ; designed which is fast and simple. In the system, water vapor is condensed from ; the air and its heavy water is estimated from its infrared absorption in the ; neighborhood of lambda = 4 mu . A compressor is provided for increasing the ; vapor pressure

J. G. Bayly; W. H. Stevens

1962-01-01

471

Water Reuse Reconsidered  

ERIC Educational Resources Information Center

|The Second National Conference on Complete WateReuse stressed better planning, management, and use of water. The sessions covered: water reuse and its problems; water's interface with air and land, and modification of these interactions by the imposition of energy; and heavy metals in the environment and methods for their removal. (BT)|

Environmental Science and Technology, 1975

1975-01-01

472

Water Chemistry Education  

ERIC Educational Resources Information Center

Describes the purpose, content, and relevancy of courses dealing with natural and artificial aquatic environments, including surface water and ground water systems as well as water and waste treatment processes. Describes existing programs which are offered at the graduate level in this subject area. (MLH)

Hindin, Ervin

1975-01-01

473

Water balance on rangelands  

Technology Transfer Automated Retrieval System (TEKTRAN)

On rangelands, the water balance is driven and defined to a great extent by the fact that potential evapotranspiration is much greater than precipitation, which in turn contributes to a large soil water deficit. As a rule, therefore, evapotranspiration is the largest component of the water balance e...

474

WATER CHEMISTRY ASSESSMENT METHODS  

EPA Science Inventory

This section summarizes and evaluates the surfce water column chemistry assessment methods for USEPA/EMAP-SW, USGS-NAQA, USEPA-RBP, Oho EPA, and MDNR-MBSS. The basic objective of surface water column chemistry assessment is to characterize surface water quality by measuring a sui...

475

International Water Facility  

NSDL National Science Digital Library

The issue-focused, peer-reviewed article proposes a global initiative to address water shortages because: about 1/3 of world's population does not have enough drinking water, almost half of world's land is without water, converting arid land to fertile land can reduce global warming, and better technology, such as desalination, would give us greater access to freshwater.

Mohamed Kassas (University of Cairo;)

2001-02-01

476

Water Quality Statistics  

ERIC Educational Resources Information Center

Water quality experiments, especially the use of macroinvertebrates as indicators of water quality, offer an ideal context for connecting statistics and science. In the STAR program for secondary students and teachers, water quality experiments were also used as a context for teaching statistics. In this article, we trace one activity that uses…

Hodgson, Ted; Andersen, Lyle; Robison-Cox, Jim; Jones, Clain

2004-01-01

477

Water Conservation: Residential Impacts.  

National Technical Information Service (NTIS)

The purpose of this study was to determine the constraints and mis-understandings associated with residential water conservation and to analyze the actual savings in dollars, water and energy that are achieved by the selection and installation of water co...

D. E. Warner

1977-01-01

478

NOAA Water Cycle Game  

NSDL National Science Digital Library

The resource is a role-playing game in which students take on the role of a water molecule and travel through nine compartments of the water cycle to gain a better understanding for the true complexity of the movement of water.

479

Saving Water Saves Energy  

Microsoft Academic Search

Hot water use in households, for showers and baths as wellas for washing clothes and dishes, is a major driver of household energyconsumption. Other household uses of water (such as irrigatinglandscaping) require additional energy in other sectors to transport andtreat the water before use, and to treat wastewater. In California, 19percent of total electricity for all sectors combined and 32

James E. McMahon; Camilla Dunham Whitehead; Peter Biermayer

2006-01-01

480

Quality of Drinking Water  

ERIC Educational Resources Information Center

|The quality of drinking water has been gaining a great deal of attention lately, especially as water delivery infrastructure continues to age. Particles of various metals such as lead and copper, and other substances like radon and arsenic could be entering drinking water supplies. Spilled-on-the-ground hydrocarbon-based substances are also…

Roman, Harry T.

2009-01-01

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