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1

Disinfection byproduct formation resulting from settled, filtered, and finished water treated by titanium dioxide photocatalysis.  

PubMed

This study evaluated strategies targeting disinfection byproduct (DBP) mitigation using TiO2 photocatalysis with varying influent water quality. A Purifics Photo-CAT Lab reactor was used to assess total trihalomethane (TTHM) and haloacetic acid (HAA) formation as a function of photocatalytic treatment using water from a conventional coagulation/flocculation/sedimentation process, granular activated carbon filtration, and a DBP hot spot in the water distribution system. Regardless of influent water quality, photocatalysis reduced DBP precursors; however, low-energy limited photocatalysis (<5kWhm(-3)), exacerbated the production of TTHMs and HAA5s beyond initial levels. Accordingly, limited photocatalysis is not a suitable option when TTHMs and HAA5s are a concern, regardless of the level of pretreatment. Limited photocatalysis yields incomplete oxidation, wherein larger, more aromatic, humic organic compounds are broken into smaller molecular weight, less aromatic, and less humic moieties, which have considerable potential to produce DBPs. More complete mineralization of DBP precursors is obtained using extended photocatalysis (80-160kWhm(-3)), which substantially decreases DBP precursors as well as TTHM and HAA5 concentrations. In order to balance DBP mitigation, energy, and chemical usage, targeted use of TiO2 photocatalysis is necessary in a water treatment train (e.g., extended photocatalysis at a distribution system hot spot, where the volumetrically high energy requirements may be justifiable). PMID:24972073

Mayer, Brooke K; Daugherty, Erin; Abbaszadegan, Morteza

2014-12-01

2

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 ...

3

New Photocatalysis for Effective Degradation of Organic Pollutants in Water  

NASA Astrophysics Data System (ADS)

The presence of harmful compounds in water supplies and in the discharge of wastewater from chemical industries, power plants, and agricultural sources is a topic of global concern. The processes and technologies available at the present time for the treatment of polluted water are varied that include traditional water treatment processes such as biological, thermal and chemical treatment. All these water treatment processes, have limitations of their own and none is cost effective. Advanced oxidation processes have been proposed as an alternative for the treatment of this kind of wastewater. Heterogeneous photocatalysis has recently emerged as an efficient method for purifying water. TiO2 has generally been demonstrated to be the most active semiconductor material for decontamination water. One significant factor is the cost of separation TiO2, which is generally a powder having a very small particle size from the water after treatment by either sedimentation or ultrafiltration. The new photocatalyst, HTiNbO5, has been tested to determine whether its photocatalytic efficiency is good enough for use in photocatalytic water purification since it has high surface area and relatively large particle size. The larger particle sizes of the porous materials facilitate catalyst removal from a solution, after purification has taken place. It can be separated from water easily than TiO2, a significant technical improvement that might eliminate the tedious final filtration necessary with a slurry. These materials are characterized and tested as water decontamination photocatalysts. The new catalyst exhibited excellent catalytic activity, but with a strong pH dependence on the photo efficiency. These results suggest that elimination of the ion exchange character of the catalyst may greatly improve its performance at various pHs. This new research proposes to study the effects of a topotactic dehydration reaction on these new porous material catalysts.

Zarei Chaleshtori, M.; Saupe, G. B.; Masoud, S.

2009-12-01

4

Light-harvesting photocatalysis for water oxidation using mesoporous organosilica.  

PubMed

An organic-based photocatalysis system for water oxidation, with visible-light harvesting antennae, was constructed using periodic mesoporous organosilica (PMO). PMO containing acridone groups in the framework (Acd-PMO), a visible-light harvesting antenna, was supported with [Ru(II)(bpy)3(2+)] complex (bpy = 2,2'-bipyridyl) coupled with iridium oxide (IrO(x)) particles in the mesochannels as photosensitizer and catalyst, respectively. Acd-PMO absorbed visible light and funneled the light energy into the Ru complex in the mesochannels through excitation energy transfer. The excited state of Ru complex is oxidatively quenched by a sacrificial oxidant (Na2S2O8) to form Ru(3+) species. The Ru(3+) species extracts an electron from IrO(x) to oxidize water for oxygen production. The reaction quantum yield was 0.34?%, which was improved to 0.68 or 1.2?% by the modifications of PMO. A unique sequence of reactions mimicking natural photosystem?II, 1)?light-harvesting, 2)?charge separation, and 3)?oxygen generation, were realized for the first time by using the light-harvesting PMO. PMID:24890840

Takeda, Hiroyuki; Ohashi, Masataka; Goto, Yasutomo; Ohsuna, Tetsu; Tani, Takao; Inagaki, Shinji

2014-07-14

5

Water oxidation electrocatalysis by a zeolitic imidazolate framework  

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

6

Water oxidation electrocatalysis by a zeolitic imidazolate framework.  

PubMed

The search for efficient water oxidation catalysts (WOCs) is of paramount importance in energy and environmental fields, but there exists no good non-noble catalyst that works under acidic and alkaline conditions. Intensive investigations have recently focused on cobalt based complex/solid catalysts. Here, we have introduced a new type of cobalt-based WOC made of metal-organic frameworks where the redox function of cobalt centres was modified by imidazolate linkers for facilitating the proton transfer process. This cobalt-containing zeolitic imidazolate framework (Co-ZIF-9) has been demonstrated for the first time to electrocatalyze the oxygen evolution reaction in a wide pH range. The catalyst was found by theoretical calculation to be capable of activating the water molecule via binding the OH-group to the metal sites with low activation barriers, while the eliminated proton was accepted by the nearby benzimidazolate motifs. This allows Co-ZIF-9 to work effectively for the electrochemical oxygen-evolution reaction. PMID:25051349

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

2014-09-01

7

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

8

Electrocatalysis of water oxidation by h2 o-capped iridium-oxide nanoparticles electrodeposited on spectroscopic graphite.  

PubMed

Electrocatalysis of water oxidation by 1.54 nm IrOx nanoparticles (NPs) immobilized on spectroscopic graphite electrodes was demonstrated to proceed with a higher efficiency than on all other, hitherto reported, electrode supports. IrOx NPs were electrodeposited on the graphite surface, and their electrocatalytic activity for water oxidation was correlated with the surface concentrations of different redox states of IrOx as a function of the deposition time and potential. Under optimal conditions, the overpotential of the reaction was reduced to 0.21 V and the electrocatalytic current density was 43 mA?cm(-2) at 1 V versus Ag/AgCl (3?M KCl) and pH 7. These results beneficially compete with previously reported electrocatalytic oxidations of water by IrOx NPs electrodeposited onto glassy carbon and indium tin oxide electrodes and provide the basis for the further development of efficient IrOx NP-based electrocatalysts immobilized on high-surface-area carbon electrode materials. PMID:25044749

Mirbagheri, Naghmehalsadat; Chevallier, Jacques; Kibsgaard, Jakob; Besenbacher, Flemming; Ferapontova, Elena E

2014-09-15

9

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

10

A Current Perspective on Photocatalysis  

SciTech Connect

The efficient conversion of solar photons into solar electricity and solar fuels is one of the most important scientific challenges of this century owing to dwindling fossil fuel reserves and the need for clean energy. While research in the direct conversion of solar energy to electricity in the areas of low-cost photovoltaic (PV) systems based on all-inorganic semiconductors, dye-sensitized solar cells, organic, and molecular PV is more technically advanced than its direct conversion to fuels, electricity may not be the ultimate primary solar energy conversion choice owing to the intermittence of solar radiation, the considerable energy loss during transmission, the availability of cost-effective storage media for electricity, and the continuing need for liquid transportation fuels. On the other hand, the direct conversion of solar photons to fuels such as H{sub 2}, CO, alcohols, and hydrocarbons using H{sub 2}O and CO{sub 2} as feedstocks offers a solution for the storage and distribution of solar energy in the form of stable chemical bonds that can be activated to provide energy at arbitrary times and locations. The latter approach to photocatalysis is generally called artificial photosynthesis, and has received renewed interest over the past five or so years. While 'photocatalysis' has not traditionally been restricted to the generation of 'solar fuels,' and has included the production of other useful chemicals, polymerization, and environmental remediation applications, the recent upsurge of interest has been driven mostly by renewable energy issues. It was the pioneering work on photo-electrochemical splitting of water to H{sub 2} and O{sub 2} by n-type TiO{sub 2} using ultraviolet light, by Fujishima and Honda in 1972, that ushered in the area of research that has come to be known as 'solar fuels,' and that has led to the terms 'photocatalysis' and 'solar fuels' becoming almost synonymous. This special issue of ChemSusChem is devoted to providing a current perspective on the field of photocatalysis. It contains invited papers from leading researchers in a wide range of important aspects of the field that address materials, photophysical, photochemical, and electrocatalysis issues. The area remains primarily the domain of basic research studies because progress toward the promise offered by the early work has (at least until recently) been slow, despite its significance having become increasingly recognized. The present collection of papers deals with new semiconductor photocatalysts, molecular catalysts for hydrogen production and water oxidation, dye-sensitized photoelectrochemical cells, and electrochemical CO{sub 2} reduction. Overall photochemical water splitting without any applied bias potential is achieved in several systems, especially under UV irradiation. Further advances are also achieved in a few semiconductor systems, such as GaZn oxynitrides or two-step (so-called 'Z-scheme') systems to produce H{sub 2} and O{sub 2} without any sacrificial reagent under visible irradiation. When band gaps of semiconductors are narrowed to absorb more visible light for greater efficiency, or when band positions are not suitable for carrying out one-electron redox processes, multielectron catalysts are required to promote proton-coupled electron transfer reactions in producing solar fuels. In homogeneous photocatalysis systems, sacrificial reagents are typically used to investigate the catalytic activity, detailed kinetics, and mechanisms of a half reaction. Photoelectrolysis systems with immobilized catalysts (metals, metal oxides, or molecular catalysts) on electrodes can separate oxidized products, such as O{sub 2}, and reduced products, such as H{sub 2}, CO, CH{sub 3}OH, and others, by means of proton- or hydroxide-conducting membranes. The following paragraphs briefly summarize these contributions. In the area of UV-driven water splitting, Townsend et al. prepared Pt-and/or IrO{sub x}-coated niobate (Nb{sub 6}O{sub 17}{sup 4-}) nanoscrolls and tested photochemical water reduction with methanol as a sacrificial rea

Fujita, E.; Muckerman, J.T.; Domen, K.

2011-02-18

11

Electrochemistry and electrocatalysis with vitamin B sub 12 in an AOT water-in-oil microemulsion  

SciTech Connect

Vitamin B{sub 12a} solubilized in water pools of highly resistive water-in-oil (w/o) microemulsions of 0.2 M Aerosol OT (AOT, bis(2-ethylhexyl) sulfosuccinate)/4 M water/isooctane gave separate reductions of base-on cob(III)alamine to base-on cob(II)alamine (E{sub 1/2} = {minus}0.03 V vs SCE) and base-on cob(II)alamine to base-off cob(I)alamine (E{sub 1/2} = {minus} 0.87 V). Diffusion coefficients suggested that vitamin B{sub 12} induces the formation of surfactant aggregates in w/o microemulsions that are larger than in solute-free systems. Relative reactivities toward reductions of three oil-soluble alkyl vicinal dihalides by electrochemically generated cob(I) alamine were modified in the microemulsion compared to isotropic water-acetonitrile. Changes in relative reactivity are not explained by simple partition of vicinal dibromides between isooctane and water and suggest specific interactions with surfactant aggregates or significant reaction in the bulk isooctane phase.

Owlia, Azita; Wang, Zhenghao; Rusling, J.F. (Univ. of Connecticut, Storrs (USA))

1989-07-05

12

Water-splitting electrocatalysis in Acid conditions using ruthenate-iridate pyrochlores.  

PubMed

The pyrochlore solid solution (Na0.33 Ce0.67 )2 (Ir1-x Rux )2 O7 (0?x?1), containing B-site Ru(IV) and Ir(IV) is prepared by hydrothermal synthesis and used as a catalyst layer for electrochemical oxygen evolution from water at pH<7. The materials have atomically mixed Ru and Ir and their nanocrystalline form allows effective fabrication of electrode coatings with improved charge densities over a typical (Ru,Ir)O2 catalyst. An in?situ study of the catalyst layers using XANES spectroscopy at the Ir LIII and Ru K?edges shows that both Ru and Ir participate in redox chemistry at oxygen evolution conditions and that Ru is more active than Ir, being oxidized by almost one oxidation state at maximum applied potential, with no evidence for ruthenate or iridate in +6 or higher oxidation states. PMID:25196322

Sardar, Kripasindhu; Petrucco, Enrico; Hiley, Craig I; Sharman, Jonathan D B; Wells, Peter P; Russell, Andrea E; Kashtiban, Reza J; Sloan, Jeremy; Walton, Richard I

2014-10-01

13

TiO2\\/AC Composites for Synergistic Adsorption-Photocatalysis Processes: Present Challenges and Further Developments for Water Treatment and Reclamation  

Microsoft Academic Search

Titanium dioxide supported on activated carbon, or TiO2\\/AC composite, exhibits bifunctionality of adsorption and photocatalysis in synergism. The authors review the TiO2\\/AC synthesis techniques, characteristics, and performances in removing organic pollutants in water. Practical issues pertinent to applications of the TiO2\\/AC composite in water treatment and reclamation are discussed. These include dispersing the particles and recovering from the product water,

Teik-Thye Lim; Pow-Seng Yap; Madhavi Srinivasan; Anthony G. Fane

2011-01-01

14

Photocatalysis Using Semiconductor Nanoclusters  

SciTech Connect

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

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

1999-01-21

15

Integration of separation and photocatalysis using an inorganic membrane modified with Si-doped TiO 2 for water purification  

Microsoft Academic Search

An unsymmetrical inorganic membrane with Si-doped TiO2 layers was fabricated for the purpose of realizing filtration and photocatalysis in a single device in water purification process. Tetra-n-butyl titanate [Ti(OC4H9)4, TBOT] and tetraethyl orthosilicate [Si(OC2H5)4, TEOS] were used as precursors of TiO2 and Si element source, and Si-doped TiO2 photocatalytic layer was coated on a commercial Al2O3 membrane by sol–gel technique.

Ning Ma; Xie Quan; Yaobin Zhang; Shuo Chen; Huimin Zhao

2009-01-01

16

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

2011-08-31

17

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

18

Photocatalysis Currently, the research  

E-print Network

analytical techniques the processes are studied in detail starting from the generation of the charge carriers and synthesized (inverse opals, mesoporous materials, doped nanoparticles) aiming to increase the photocatalytic Photocatalysis and Nanotechnology Contact #12;Bioprocess Engineering Cultivation processes of bacteria, fungi

Vollmer, Heribert

19

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

20

DNA sensing by electrocatalysis with hemoglobin  

PubMed Central

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

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

2012-01-01

21

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

SciTech Connect

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

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

2013-10-15

22

Photocatalysis-assisted water filtration: using TiO2-coated vertically aligned multi-walled carbon nanotube array for removal of Escherichia coli O157:H7.  

PubMed

A porous ceramic was coated with vertically aligned multi-walled carbon nanotubes (MWCNTs) by spray pyrolysis. Titanium dioxide (TiO2) nanoparticles were then coated onto this densely aligned MWCNT. The presence of TiO2/MWCNT interfacial arrays was confirmed by X-ray diffraction (XRD), scanning electron microscope-energy dispersive analysis of X-ray (SEM-EDAX) and transmission electron microscope (TEM). This is a novel report in which water loaded with a most dreadful enterohemorrhagic pathogenic strain of Escherichia coli O157:H7 was filtered through TiO2/MWCNT coated porous ceramic filter and then analysed. Bacterial removal performance was found to be significantly lower in control i.e. plain porous ceramic (P<0.05) as compared to TiO2/MWCNT coated ceramic. The photocatalytic killing rate constant for TiO2-ceramic and MWCNT/TiO2-ceramic under fluorescent light was found be 1.45×10(-2) min(-1) and 2.23×10(-2) min(-1) respectively. Further, when I-V characteristics were performed for TiO2/MWCNT composite, it was corroborated that the current under light irradiation is comparatively higher than that in dark, thus proving it to be photocatalytically efficient system. The enhanced photocatalysis may be a contribution of increased surface area and charge transfer rate as a consequence of aligned MWCNT network. PMID:23910358

Oza, Goldie; Pandey, Sunil; Gupta, Arvind; Shinde, Sachin; Mewada, Ashmi; Jagadale, Pravin; Sharon, Maheshwar; Sharon, Madhuri

2013-10-01

23

Inactivation of algal blooms in eutrophic water of drinking water supplies with the photocatalysis of TiO2 thin film on hollow glass beads.  

PubMed

Photocatalytic inactivation of algae, Anabaena, Microcystis, and Melosira, was carried out with TiO2-coated Pyrex hollow glass beads under the illumination of UV light (370 nm wavelength). After being irradiated with UV light in the presence of the TiO2-coated Pyrex glass beads, Anabaena and Microcystis, known as typical cyanobacteria, lost their photosynthetic activity, and the string of Anabaena cells and the colonies of Microcystis cells were completely separated into individual spherical ones. In the case of Melosira, which is a typical diatom, however, somewhat lower photocatalytic inactivation efficiency was obtained, which was believed to be due to the presence of the inorganic siliceous wall surrounding the cells of Melosira. The TiO2-coated hollow glass beads could successfully be employed for the practical application in a eutrophicated river under sunlight. More than 50% of the chlorophyll-a concentration could be reduced by the action of TiO2 photocatalysis. PMID:16445183

Kim, S-C; Lee, D-K

2005-01-01

24

Open-framework gallium borate with boric and metaboric acid molecules inside structural channels showing photocatalysis to water splitting.  

PubMed

An open-framework gallium borate with intrinsic photocatalytic activities to water splitting has been discovered. Small inorganic molecules, H3BO3 and H3B3O6, are confined inside structural channels by multiple hydrogen bonds. It is the first example to experimentally show the structural template effect of boric acid in flux synthesis. PMID:24512540

Gao, Wenliang; Jing, Yan; Yang, Jia; Zhou, Zhengyang; Yang, Dingfeng; Sun, Junliang; Lin, Jianhua; Cong, Rihong; Yang, Tao

2014-03-01

25

Photocatalysis. A multi-faceted concept for green chemistry.  

PubMed

Photocatalysis (by semiconductors, molecules and ions) is used in such diverse applications as water hydrolysis for producing hydrogen as fuel, organic synthesis and the recovery of polluted effluents. This tutorial review discusses the common principles of such applications and their role in green chemistry. PMID:19551179

Ravelli, Davide; Dondi, Daniele; Fagnoni, Maurizio; Albini, Angelo

2009-07-01

26

Environmental green chemistry as defined by photocatalysis.  

PubMed

Photocatalysis is efficient in several fields. Firstly, in selective mild oxidation: oxidation of gas and liquid hydrocarbons (alkanes, alkenes, cyclo-alkanes, aromatics) into aldehydes and ketons. Primary and secondary alcohols are also oxidized into their corresponding aldehydes or ketones. The high selectivity was ascribed to a photoactive neutral, atomic oxygen species. Once platinized (only 0.5wt.% Pt) titania may catalyze reactions involving hydrogen (deuterium-alkane isotopic exchange and alcohol dehydrogenation). For fine chemicals, high initial selectivities enable titania to address most of the twelve principles of "green chemistry", such as the synthesis of 4-tert-butyl-benzaldehyde, an important intermediate in perfume industry by direct selective oxidation of 4-tert-butyl-toluene with air. A new field recently appeared: thio-photocatalysis. Oxygen was replaced by sulfur, using H(2)S as a convenient and reactive source. For instance, the conversion of propene in 1-propanthiol was successfully obtained. The reaction was performed using either CdS or TiO(2). The latter was much more active than CdS. In environmental photocatalysis, titania becomes a total oxidation catalyst once in presence of water because of the photogeneration of OH radicals by neutralization of OH(-) surface groups by positive holes. Many toxic inorganic ions are oxidized in their harmless upper oxidized state. The total degradation of organic pollutants (pesticides, herbicides, insecticides, fungicides, dyes, etc. ...) is the main field of water photocatalytic decontamination. The UVA solar spectrum can de advantageously used as demonstrated by many campaigns performed in the solar pilot plant at the "Plataforma Solar de Almeria" (Spain). PMID:17532130

Herrmann, J-M; Duchamp, C; Karkmaz, M; Hoai, Bui Thu; Lachheb, H; Puzenat, E; Guillard, C

2007-07-31

27

Electrocatalysis of anodic oxidation of ethanol  

NASA Astrophysics Data System (ADS)

The results of fundamental and applied studies in the field of electrocatalysis of anodic oxidation of ethanol in fuel cells are considered. Features of the mechanism of ethanol electrooxidation are discussed as well as the structure and electrochemical properties of the most widely used catalysts of this process. The prospects of further studies of direct ethanol fuel cells with alkaline and acidic electrolytes are outlined. The bibliography includes 166 references.

Tarasevich, M. R.; Korchagin, O. V.; Kuzov, A. V.

2013-11-01

28

Single-Site Copper(II) Water Oxidation Electrocatalysis: Rate Enhancements with HPO4 (2-) as a Proton Acceptor at pH?8.  

PubMed

The complex Cu(II) (Py3 P) (1) is an electrocatalyst for water oxidation to dioxygen in H2 PO4 (-) /HPO4 (2-) buffered aqueous solutions. Controlled potential electrolysis experiments with 1 at pH?8.0 at an applied potential of 1.40?V versus the normal hydrogen electrode resulted in the formation of dioxygen (84?% Faradaic yield) through multiple catalyst turnovers with minimal catalyst deactivation. The results of an electrochemical kinetics study point to a single-site mechanism for water oxidation catalysis with involvement of phosphate buffer anions either through atom-proton transfer in a rate-limiting O?O bond-forming step with HPO4 (2-) as the acceptor base or by concerted electron-proton transfer with electron transfer to the electrode and proton transfer to the HPO4 (2-) base. PMID:25243584

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

2014-11-01

29

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

30

Electrocatalysis issues in polymer electrolyte fuel cells  

NASA Astrophysics Data System (ADS)

Various electrocatalysis issues of importance 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 CO2 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 of the extra, exposed Pt in the latter case. The tolerance of Pt-Ru alloy thin film anodes to CO and CO2 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.

31

Particle size and support effects in electrocatalysis.  

PubMed

Researchers increasingly recognize that, as with standard supported heterogeneous 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 can determine 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

2013-08-20

32

HIgh Temperature Photocatalysis over Semiconductors  

NASA Astrophysics Data System (ADS)

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

Westrich, Thomas A.

33

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...

34

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...

35

Bactericidal efficiency and mode of action: a comparative study of photochemistry and photocatalysis.  

PubMed

In order to compare the disinfection potential of photocatalysis and photochemistry, the effects of these two processes on bacteria in water were investigated under exposure to UV-A and UV-C. The well-known bacterial model Escherichia coli (E. coli) was used as the experimental organism. Radiation exposure was produced with an HPK 125 W lamp and the standard TiO(2) Degussa P-25 was used as the photocatalyst. Firstly, the impact of photocatalysis and photochemistry on the cultivability of bacterial cells was investigated. UV-A radiation resulted in low deleterious effects on bacterial cultivability but generated colonies of size smaller than average. UV-C photocatalysis demonstrated a greater efficiency than UV-A photocatalysis in altering bacterial cultivability. From a cultivability point of view only, UV-C radiation appeared to be the most deleterious treatment. A rapid epifluorescence staining method using the LIVE/DEAD Bacterial Viability Kit was then used to assess the modifications in bacterial membrane permeability. UV-A radiation did not induce any alterations in bacterial permeability for 420 min of exposure whereas only a few minutes of exposure to UV-C radiation, with the same total radiance intensity, induced total loss of permeability. Moreover, after 20 and 60 min of exposure to UV-C and UV-A photocatalysis respectively, all bacteria lost their membrane integrity, suggesting that the bacterial envelope is the primary target of reactive oxygen species (ROS) generated at the surface of TiO(2) photocatalyst. These results were further confirmed by the formation of malondialdehyde (MDA) during the photocatalytic inactivation of bacterial cells and suggest that destruction of the cell envelope is a key step in the bactericidal action of photocatalysis. The oxidation of bacterial membrane lipids was also correlated with the monitoring of carboxylic acids, which can be considered as representatives of lipid peroxidation by-products. Finally, damages to bacterial morphology induced by UV-C photocatalysis and photochemistry were investigated through Scanning electron microscopy (SEM). Bacterial cells were observed on microscopy pictures at exposure durations corresponding to a loss of cultivability. After 90 min of exposure to UV-C radiation, bacterial cells showed little alteration of their outer membrane whereas they suffered deep deleterious damages under UV-C photocatalysis exposure. PMID:22503496

Pigeot-Rémy, S; Simonet, F; Atlan, D; Lazzaroni, J C; Guillard, C

2012-06-15

36

Engineering microbial electrocatalysis for chemical and fuel production.  

PubMed

In many biotechnological areas, metabolic engineering and synthetic biology have become core technologies for biocatalyst development. Microbial electrocatalysis for biochemical and fuel production is still in its infancy and reactions rates and the product spectrum are currently very low. Therefore, molecular engineering strategies will be crucial for the advancement and realization of many new bioproduction routes using electroactive microorganisms. The complex and unresolved biochemistry and physiology of extracellular electron transfer and the lack of molecular tools for these new non-model hosts for genetic engineering constitute the major challenges for this effort. This review is providing an insight into the current status, challenges and promising approaches of pathway engineering for microbial electrocatalysis. PMID:24709348

Rosenbaum, Miriam A; Henrich, Alexander W

2014-10-01

37

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

38

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

39

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

40

Removal of gas-phase ammonia and hydrogen sulfide using photocatalysis, nonthermal plasma, and combined plasma and photocatalysis at pilot scale.  

PubMed

This study focuses on the removal of gas-phase ammonia (NH3) and hydrogen sulfide (H2S) in a continuous reactor. Photocatalysis and surface dielectric barrier discharge (SDBD) plasma are studied separately and combined. Though the removal of volatile organic compounds by coupling plasma and photocatalysis has been reported on a number of studies in laboratory scale, this is as far as we know the first time that it is used to remove inorganic malodorous pollutants. While each separate process is able to degrade ammonia and hydrogen sulfide, a synergetic effect appears when they are combined at a pilot scale, leading to removal capacity higher than the sum of each separate process. The removal capacity is higher when the gas circulates at a higher flow rate and when pollutant concentration is higher. The presence of water vapor in the gas is detrimental to the efficiency of the process. Operating conditions also influence the production of nitrogen oxides and ozone. PMID:24996941

Maxime, Guillerm; Aymen Amine, Assadi; Abdelkrim, Bouzaza; Dominique, Wolbert

2014-11-01

41

Environmental green chemistry as defined by photocatalysis  

Microsoft Academic Search

Photocatalysis is efficient in several fields. Firstly, in selective mild oxidation: oxidation of gas and liquid hydrocarbons (alkanes, alkenes, cyclo-alkanes, aromatics) into aldehydes and ketons. Primary and secondary alcohols are also oxidized into their corresponding aldehydes or ketones. The high selectivity was ascribed to a photoactive neutral, atomic oxygen species. Once platinized (only 0.5wt.% Pt) titania may catalyze reactions involving

J.-M. Herrmann; C. Duchamp; M. Karkmaz; Bui Thu Hoai; H. Lachheb; E. Puzenat; C. Guillard

2007-01-01

42

[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

43

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

E-print Network

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

Bonnet, Nicéphore

2011-01-01

44

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

45

Bismuth oxyhalide nanomaterials: layered structures meet photocatalysis.  

PubMed

In recent years, layered bismuth oxyhalide nanomaterials have received more and more interest as promising photocatalysts because their unique layered structures endow them with fascinating physicochemical properties; thus, they have great potential photocatalytic applications for environment remediation and energy harvesting. In this article, we explore the synthesis strategies and growth mechanisms of layered bismuth oxyhalide nanomaterials, and propose design principles of tailoring a layered configuration to control the nanoarchitectures for high efficient photocatalysis. Subsequently, we focus on their layered structure dependent properties, including pH-related crystal facet exposure and phase transformation, facet-dependent photoactivity and molecular oxygen activation pathways, so as to clarify the origin of the layered structure dependent photoreactivity. Furthermore, we summarize various strategies for modulating the composition and arrangement of layered structures to enhance the photoactivity of nanostructured bismuth oxyhalides via internal electric field tuning, dehalogenation effect, surface functionalization, doping, plasmon modification, and heterojunction construction, which may offer efficient guidance for the design and construction of high-performance bismuth oxyhalide-based photocatalysis systems. Finally, we highlight some crucial issues in engineering the layered-structure mediated properties of bismuth oxyhalide photocatalysts and provide tentative suggestions for future research on increasing their photocatalytic performance. PMID:24975748

Li, Jie; Yu, Ying; Zhang, Lizhi

2014-08-01

46

Photolysis and photocatalysis of bisphenol A: identification of degradation products by liquid chromatography with electrospray ionization\\/time-of-flight\\/mass spectrometry (LC\\/ESI\\/ToF\\/MS)  

Microsoft Academic Search

Bisphenol A is a commonly known endocrine-disrupting compound detected in environmental water samples. The persistence of this compound has been studied by photolysis and photocatalysis studies. In this work, several experiments were performed in order to identify the degradation products under various conditions and in different types of matrices (deionized and waste water). These studies included the influence of sodium

M. Mezcua; I. Ferrer; M. D. Hernando; A. R. Fernández-Alba

2006-01-01

47

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

48

Energy Conversion and Utilization Technologies Program (ECUT) electrocatalysis research  

NASA Technical Reports Server (NTRS)

The general field of electrocatalysis, from both the technical and business standpoints is accessed and research areas and approaches most likely to lead to substantial energy/cost savings are identified. The overall approach was to compile and evaluate available information, relying heavily on inputs/recommendations of research managers and technical personnel in responsible positions in industry and at universities. Some promising approaches identified to date include the use of transition metal compounds as electrocatalysts and the use of the new electrochemical photocapacitance spectroscopy (EPS) technique for electrocatalyst characterization/development. For the first time, an oxygen electrocatalyst based on the K2NiF4 structure was synthesized, investigated and compared with a perovskite analog. Results show that this class of materials, based on Ni(3+), forms very efficient and stable O2 anodes in basic solution and suggest that other structure-types be examined in this regard. The very difficult problem of dinitrogen and carbon dioxide electroreductions is addressed through the use of biological model systems which can mimic the enzyme processes in nature.

Warren, L. F.

1984-01-01

49

Electrochemical responses and electrocatalysis at single au nanoparticles.  

PubMed

Steady-state electrochemical responses have been obtained at single Au nanoparticles using Pt nanoelectrodes. A Au single-nanoparticle electrode (SNPE) is constructed by chemically immobilizing a single Au nanoparticle at a SiO(2)-encapsulated Pt disk nanoelectrode, which was previously modified by an amine-terminated silane. The Au SNPE has been characterized by transmission electron microscopy, underpotential deposition of Cu, and steady-state cyclic voltammetry. It has been found that the presence of a single Au nanoparticle enhances the electron transfer from the Pt nanoelectrode to the redox molecules, and the voltammetric response at the Au SNPE depends on the size of the Au nanoparticle. The Au SNPE has been utilized to examine the oxygen-reduction reaction in a KOH solution to explore the feasibility of measuring the electrocatalytic activity at a single-nanoparticle level. It has been shown that the electrocatalytic activity of single Au nanoparticles can be directly measured using SNPEs, and the electrocatalytic activity is dependent on the size of the Au nanoparticles. This study can help to understand the structure-function relationship in nanoparticle-based electrocatalysis. PMID:20148588

Li, Yongxin; Cox, Jonathan T; Zhang, Bo

2010-03-10

50

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

51

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

52

Nanogold plasmonic photocatalysis for organic synthesis and clean energy conversion.  

PubMed

This review provides the basic concepts, an overall survey and the state-of-the art of plasmon-based nanogold photocatalysis using visible light including fundamental understanding and major applications to organic reactions and clean energy-conversion systems. First, the basic concepts of localized surface plasmon resonance (LSPR) are recalled, then the major preparation methods of AuNP-based plasmonic photocatalysts are reviewed. The major part of the review is dedicated to the latest progress in the application of nanogold plasmonic photocatalysis to organic transformations and energy conversions, and the proposed mechanisms are discussed. In conclusion, new challenges and perspectives are proposed and analyzed. PMID:25017125

Wang, Changlong; Astruc, Didier

2014-10-21

53

Enhanced decolourisation ability of laccase towards various synthetic dyes by an electrocatalysis technology.  

PubMed

Laccase in culture filtrates of Trametes versicolor degraded a number of structurally different dyes by about 30% after 30 min though only 5% of Azure B was degraded in 1 h and Poly R-478 and fuchsin were not degraded at all even after 24 h. However, by using enzymatic electrocatalysis technology all dyes were decolourised in about 30 to 135 min. PMID:12882152

Cameselle, C; Pazos, M; Lorenzo, M; Sanromán, M A

2003-04-01

54

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

55

Protein structure-sensitive electrocatalysis at dithiothreitol-modified electrodes.  

PubMed

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

Ostatná, Veronika; Cernocká, Hana; Palecek, Emil

2010-07-14

56

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

2013-07-17

57

Photodecomposition of bisphenol A on nanometer-sized TiO2 thin film and the associated biological toxicity to zebrafish (Danio rerio) during and after photocatalysis.  

PubMed

We investigated the relationship between the TiO2 photocatalytic decomposition of bisphenol A and biological toxicity to zebrafish (Danio rerio). TiO2 particles, which prepared using a solvothermal method, were applied to produce a nanometer-sized TiO2 thin film. An alcoholic solution containing the TiO2 particles and an inorganic binder was directly coated on the UV-lamp substrate. It was equipped in a photoreactor that was manufactured in our laboratory. The attachment of the thin TiO2 film to the UV-lamp substrate resulted in a stable and transparent coating. The TiO2 particles on the thin film were approximately 20-30 nm in size, and the resulting film thickness was approximately 200 nm after a single coat. The bisphenol A, which was eluted from epoxy resin in a drinking water tank, was completely degraded by the TiO2 photocatalysis. We initially detected approximately 7.8 ng/ml of bisphenol A in the epoxy-resin tank, but its concentration was undetectable after a 48-h photocatalytic reaction over TiO2. We observed a decreased survival rate in zebrafish that were reared in water exposed to the leaching process of the epoxy resin. After the photocatalysis, however, no toxic effects on the hatching rates or morphogenesis of the zebrafish were observed. In summary, toxicity during the TiO2 photocatalysis was observed; however, toxicity was no longer observed once the bisphenol A was completely decomposed by the TiO2 photocatalysis. On the basis of these experimental observations, we suggest that TiO2 photocatalysis can be adopted as a treatment method to purify an epoxy-resin tank. PMID:16620905

Yeo, Min-Kyeong; Kang, Misook

2006-05-01

58

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

59

New Electrochemical Methods for Studying Nanoparticle Electrocatalysis and Neuronal Exocytosis  

NASA Astrophysics Data System (ADS)

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

Cox, Jonathan T.

60

Graphene thickness-controlled photocatalysis and surface enhanced Raman scattering  

NASA Astrophysics Data System (ADS)

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

Kuo, Cheng-Chi; Chen, Chun-Hu

2014-10-01

61

Electrocatalysis of borohydride oxidation: a review of density functional theory approach combined with experimental validation  

NASA Astrophysics Data System (ADS)

The electrocatalysis of borohydride oxidation is a complex, up-to-eight-electron transfer process, which is essential for development of efficient direct borohydride fuel cells. Here we review the progress achieved by density functional theory (DFT) calculations in explaining the adsorption of BH4- on various catalyst surfaces, with implications for electrocatalyst screening and selection. Wherever possible, we correlate the theoretical predictions with experimental findings, in order to validate the proposed models and to identify potential directions for further advancements.

Sison Escaño, Mary Clare; Lacdao Arevalo, Ryan; Gyenge, Elod; Kasai, Hideaki

2014-09-01

62

Electrocatalysis and electroanalysis of nickel, its oxides, hydroxides and oxyhydroxides toward small molecules.  

PubMed

The electrocatalysis toward small molecules, especially small organic compounds, is of importance in a variety of areas. Nickel based materials such as nickel, its oxides, hydroxides as well as oxyhydroxides exhibit excellent electrocatalysis performances toward many small molecules, which are widely used for fuel cells, energy storage, organic synthesis, wastewater treatment, and electrochemical sensors for pharmaceutical, medical, food or environmental analysis. Their electrocatalytic mechanisms are proposed from three aspects such as Ni(OH)2/NiOOH mediated electrolysis, direct electrocatalysis of Ni(OH)2 or NiOOH. Under exposure to air or aqueous solution, two distinct layers form on the Ni surface with a Ni hydroxide layer at the air-oxide interface and an oxide layer between the metal substrate and the outer hydroxide layer. The transformation from nickel or its oxides to hydroxides or oxyhydroxides could be further speeded up in the strong alkaline solution under the cyclic scanning at relatively high positive potential. The redox transition between Ni(OH)2 and NiOOH is also contributed to the electrocatalytic oxidation of Ni and its oxides toward small molecules in alkaline media. In addition, nickel based materials or nanomaterials, their preparations and applications are also overviewed here. PMID:24211454

Miao, Yuqing; Ouyang, Lei; Zhou, Shilin; Xu, Lina; Yang, Zhuoyuan; Xiao, Mingshu; Ouyang, Ruizhuo

2014-03-15

63

Graphene thickness-controlled photocatalysis and surface enhanced Raman scattering.  

PubMed

Exceptional photocatalytic enhancement of graphene-semiconductor composites has been widely reported, but our understanding of the role that graphene plays in this enhancement remains limited, which arises from the difficulty of precisely controlling graphene hybridization. Here we present a general platform of a graphene-semiconductor hybrid panel (GHP) system wherein a precise number of layers of graphene are hybridized with photoactive semiconductors (e.g. TiO2, ZnO) to study systematically how graphene affects the photocatalysis. The results show that the graphene enhancement of the photocatalysis depends on the number of graphene layers, with the maximum performance observed at 3 layers. Photodeposited indicators of gold particles further reveal that graphene thickness governs the density of photocatalytic sites and charge transfer efficiency at the graphene-semiconductor interfaces. We suggest that quantized energy levels caused by different numbers of stacked graphene sheets along the vector normal to the graphene basal plane affect the charge transfer routes and lead to the graphene thickness-controlled photocatalysis. GHP substrates deposited with gold particles are promising, uniform substrates for surface enhanced Raman scattering (SERS) applications with the enhancement factor as high as ?10(8) on 3-layer graphene. PMID:25226177

Kuo, Cheng-Chi; Chen, Chun-Hu

2014-10-01

64

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

PubMed

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

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

2014-01-01

65

Non-thermal Plasma - Nanometer TiO2 Photocatalysis for Formaldehyde Decomposition  

E-print Network

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

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

2006-01-01

66

Roles of cocatalysts in photocatalysis and photoelectrocatalysis.  

PubMed

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

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

2013-08-20

67

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

SciTech Connect

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

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

2010-10-01

68

Synthesis and investigation of novel nanomaterials for improved photocatalysis  

NASA Astrophysics Data System (ADS)

Since the discovery of the photocatalytic splitting of water on TiO 2 electrode by Fujishima and Honda in 1972, enormous effort has been spent on the study of TiO2 under light illumination, due to its various potential applications, such as photovoltaics and photocatalysis. The optical properties, in particular the absorption, of TiO2 are essential to its photon-driven applications. Typically, TiO2 absorbs in the UV regime, which is only a small fraction of the sun's energy (<10%). The performance of TiO2 can be enhanced by shifting the onset of its absorption from the UV to the visible region. Metals have been employed to tune the electronic structure of TiO2-based material. The photocatalytic reactivity of metal-doped TiO2 depends on many factors, and metal doping can result in thermal instability and increased carrier trapping. The desired visible-light absorption of TiO2 can be also achieved by using main group dopants. In this dissertation, different non-metal elements, C, N and S, are incorporated to the lattice of TiO2 to induce the absorption in the visible-light regime. Both bottom-up and top-down methods are used to synthesize these doped TiO2 nanoparticles. The optical, physical, electronic and photocatalytic properties of these doped TiO2 nanoparticles are explored with different techniques. The relationship between the optical, electronic and photocatalytic properties are elucidated. The photocatalytic performance of the doped TiO2 nanoparticles is applied not only to the model photodegradation of methylene blue, but also on other industrial dyes under natural sunlight illumination. The non-metal-doped TiO2 nanoparticles demonstrated improved photocatalytic performance over the non-doped TiO2 nanoparticles, i.e. in the visible-light regime. On the other hand, as the size of nanoparticles decreases, the surface-to-volume ratio increases dramatically (˜1/r), so does the surface area (1/r 2). The high surface area brought by the small size of nanoparticles becomes more important for the optical and electronic properties of nanomaterials, compared to the bulk materials. Besides the well-know quantum-confinement effect, the surface effect should be taken into account for small nanoparticles. Thus in this dissertation, the synthesis and properties of II-VI (CdSe, CdSe/CdS) semiconductor nanoparticles are investigated to elucidate the surface effect on the properties of nanoparticles, which helps to understand the photocatalytic property of TiO2 nanomaterials, since the main catalytic reactions occur on the surface. The gradual crystallization of small nanoparticles, as well as its effect on the optical properties is elucidated. The interface strain/stress in the CdSe/CdS core/shell system is explored on their optical properties, as well as the hot carrier relaxation dynamics in CdSe nanoparticles.

Chen, Xiaobo

69

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

2013-10-28

70

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

E-print Network

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

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

2006-01-01

71

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

72

Visible Light Photocatalysis: The Development of Photocatalytic Radical Ion Cycloadditions  

PubMed Central

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

Yoon, Tehshik P.

2013-01-01

73

Epilayer control of photodeposited materials during UV photocatalysis  

NASA Astrophysics Data System (ADS)

Epilayer control of photoassisted oxidation and reduction on the ferroelectric PbTiO3 polar surface was investigated. Photo-oxidation of a AgNO3 electrolyte resulting in formation of Ag7NO11 particles was observed on the PbTiO3/Nb:SrTiO3 film surface; whereas PbTiO3/SrRuO3/SrTiO3 leads to AgNO3 reduction under UV illumination. The oxidation reaction resulting in the formation of Ag7NO11 is explained in terms of a rectifying interface between PbTiO3 and Nb:SrTiO3, controlling the charge transport during UV photocatalysis.

Takahashi, R.; Katayama, M.; Dahl, Ø.; Grepstad, J. K.; Matsumoto, Y.; Tybell, T.

2009-06-01

74

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

NASA Technical Reports Server (NTRS)

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

Ryan, robert E.; Underwood, Lauren W.

2007-01-01

75

Fabrication of nanostructured materials using porous alumina template and their applications for sensing and electrocatalysis.  

PubMed

Ordered porous anodic aluminum oxide templates have been used extensively for the preparation of various functional nanostructures. Researches on these nanostructured materials for various purposes have received a tremendous attention during recent years. A review of the literature on the fabrication of nanostructured materials using ordered porous anodic aluminum oxide templates and their applications is presented. A survey of the preparation of anodic aluminum oxide films is given first, with an emphasis on highly ordered anodic aluminum oxide films, as the ordered structure is the key point to prepare nanomaterials with uniform morphology. Methods for the fabrication of nanostructured materials using ordered porous anodic aluminum oxide templates are presented next: including dip filling, ion-encountering reaction, electroplating, and chemical vapor deposition method. Several typical examples of each preparation method are given. Finally, overview of applications on these nanostructured materials is presented, particular emphasis is focused on the field of sensing and electrocatalysis. PMID:19437960

Piao, Yuanzhe; Kim, Hasuck

2009-04-01

76

Facilitation of high-rate NADH electrocatalysis using electrochemically activated carbon materials.  

PubMed

Electrochemical activation of glassy carbon, carbon paper and functionalized carbon nanotubes via high-applied-potential cyclic voltammetry leads to the formation of adsorbed, redox active functional groups and increased active surface area. Electrochemically activated carbon electrodes display enhanced activity toward nicotinamide adenine dinucleotide (NADH) oxidation, and more importantly, dramatically improved adsorption of bioelectrochemically active azine dyes. Adsorption of methylene green on an electroactivated carbon electrode yields a catalyst layer that is 1.8-fold more active toward NADH oxidation than an electrode prepared using electropolymerized methylene green. Stability studies using cyclic voltammetry indicate 70% activity retention after 4000 cycles. This work further facilitates the electrocatalysis of NADH oxidation for bioconversion, biosensor and bioenergy processes. PMID:24780505

Li, Hanzi; Li, Rui; Worden, Robert M; Barton, Scott Calabrese

2014-05-14

77

One-pot synthesis of Pt/carbon nanotubes by self-regulated reduction for electrocatalysis.  

PubMed

This paper describes a method for size-controlled synthesis of Pt nanoparticles and their attachment to the sidewalls of multiwall carbon nanotubes (CNTs) by self-regulated reduction of sodium n-dodecyl sulfate (SDS), without surface pretreatment. The size of the Pt nanoparticles is controlled by adjusting the concentration of SDS. When Pt/CNTs are heated to 500 degrees C in N2 atmosphere, Pt nanochains are formed on the CNTs; some of these nanochains contain small islands. Electrochemical measurements confirm that the electroactivities of the Pt/CNT nanocatalysts increase with a decrease in the size of the Pt nanoparticles. Additionally, comparing with the heated Pt/CNT nanocatalysts containing smooth Pt nanochains, the heated Pt/CNT nanocatalysts containing Pt nanochains with small Pt islands show higher electrocatalysis activities and stability. PMID:21128473

Lee, Chien-Liang; Wu, Shi-Chi

2010-07-01

78

High efficiency photocatalysis for pollutant degradation with MoS2/C3N4 heterostructures.  

PubMed

Porous graphitic carbon nitride was synthesized by controllable thermal polymerization of urea in air. Their textural, electrical, and optical properties were tuned by varying the heating rate. The presence of proper residual oxygen in carbon nitride matrix had enhanced light absorption and inhibited the recombination of charge carriers. Furthermore, the MoS2 nanosheets were coupled into the carbon nitride to form MoS2/C3N4 heterostructures via a facile ultrasonic chemical method. The optimized MoS2/C3N4 heterostructure with 0.05 wt % MoS2 showed a reaction rate constant as high as 0.301 min(-1), which was 3.6 times that of bare carbon nitride. As analyzed by SEM, TEM, UV-vis absorption, PL and photoelectrochemical measurements, intimate contact interface, extended light response range, enhanced separation speed of charge carriers, and high photocurrent density upon MoS2 coupling led to the photocatalytic promotion of the MoS2/C3N4 heterostructures. In this architecture, MoS2 served as electron trapper to extend the lifetime of separated electron-hole pairs. Meanwhile, the accumulated holes on the surface of carbon nitride oxidized the organic dye directly, which was a predominant process in the photodegradation of organic pollutants in water treatment. The promotional mechanisms and principles reported here would have great significance in heterogeneous photocatalysis. PMID:25017627

Li, Qian; Zhang, Ning; Yang, Yong; Wang, Guozhong; Ng, Dickon H L

2014-07-29

79

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

2011-02-28

80

Water Purification Systems  

NASA Technical Reports Server (NTRS)

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

1992-01-01

81

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

82

Transition metal (Mn, Fe, Co, Ni)-doped graphene hybrids for electrocatalysis.  

PubMed

The development of electrocatalysts is crucial for renewable energy applications. Metal-doped graphene hybrid materials have been explored for this purpose, however, with much focus on noble metals, which are limited by their low availability and high costs. Transition metals may serve as promising alternatives. Here, transition metal-doped graphene hybrids were synthesized by a simple and scalable method. Metal-doped graphite oxide precursors were thermally exfoliated in either hydrogen or nitrogen atmosphere; by changing exfoliation atmospheres from inert to reductive, we produced materials with different degrees of oxidation. Effects of the presence of metal nanoparticles and exfoliation atmosphere on the morphology and electrocatalytic activity of the hybrid materials were investigated using electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and cyclic voltammetry. Doping of graphene with transition metal nanoparticles of the 4th?period significantly influenced the electrocatalysis of compounds important in energy production and storage applications, with hybrid materials exfoliated in nitrogen atmosphere displaying superior performance over those exfoliated in hydrogen atmosphere. Moreover, nickel-doped graphene hybrids displayed outstanding electrocatalytic activities towards reduction of O2 when compared to bare graphenes. These findings may be exploited in the research field of renewable energy. PMID:23495248

Toh, Rou Jun; Poh, Hwee Ling; Sofer, Zden?k; Pumera, Martin

2013-06-01

83

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

84

From single crystal surfaces to single atoms: investigating active sites in electrocatalysis  

NASA Astrophysics Data System (ADS)

Electrocatalytic processes will undoubtedly be at the heart of energising future transportation and technology with the added importance of being able to create the necessary fuels required to do so in an environmentally friendly and cost effective manner. For this to be successful two almost mutually exclusive surface properties need to be reconciled, namely producing highly active/reactive surface sites that exhibit long term stability. This article reviews the various approaches which have been undertaken to study the elusive nature of these active sites on metal surfaces which are considered as adatoms or clusters of adatoms with low coordination number. This includes the pioneering studies at extended well defined stepped single crystal surfaces using cyclic voltammetry up to the highly sophisticated in situ electrochemical imaging techniques used to study chemically synthesised nanomaterials. By combining the information attained from single crystal surfaces, individual nanoparticles of defined size and shape, density functional theory calculations and new concepts such as mesoporous multimetallic thin films and single atom electrocatalysts new insights into the design and fabrication of materials with highly active but stable active sites can be achieved. The area of electrocatalysis is therefore not only a fascinating and exciting field in terms of realistic technological and economical benefits but also from the fundamental understanding that can be acquired by studying such an array of interesting materials.

O'Mullane, Anthony P.

2014-03-01

85

Microwave assisted photocatalysis of mono-chloroacetic acid over nanoporous titanium (IV) oxide thin films  

E-print Network

Microwave assisted photocatalysis of mono-chloroacetic acid over nanoporous titanium (IV) oxide Microwaves are well known for their heating effects on polar substances and are widely used domestically and industrially. Recently, microwaves have been used to assist photochemical and photocatalytic reactions

Cirkva, Vladimir

86

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

87

Comparison of the degradations of diphenamid by homogeneous photolysis and heterogeneous photocatalysis in aqueous solution.  

PubMed

In this work, the homogeneous and heterogeneous degradations of diphenamid (DPA) in aqueous solution were conducted by direct photolysis with UVC (254nm) and by photocatalysis with TiO(2)/UVA (350nm), and the experimental results were compared. It was found that the homogeneous photolysis by UVC irradiation alone was quite efficient to degrade DPA up to 100% after 360min, but was very inefficient to mineralize its intermediates in terms of dissolved organic carbon reduction of only 8%. In contrast, the heterogeneous photocatalysis with TiO(2)/UVA showed relatively a lower degree of DPA degradation (51%), but a higher degree of its mineralization (11%) after 360min. These results reveal that the photocatalysis process has relatively poor selectivity to degrade different compounds including various intermediates from the DPA degradation, which is beneficial to its mineralization. In addition, over 20 intermediates were identified by LC-MS and (1)H NMR analyses. Based on the identified intermediates, the reaction mechanisms and the detailed pathways of the DPA degradation by photolysis and photocatalysis were proposed, and are presented in this paper. PMID:20494398

Liang, Hai-chao; Li, Xiang-zhong; Yang, Yin-hua; Sze, Kong-hung

2010-06-01

88

UV and Solar TiO2 Photocatalysis of Brevetoxins (PbTxs)  

PubMed Central

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

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

2012-01-01

89

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

PubMed

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

Affam, Augustine Chioma; Chaudhuri, Malay

2013-11-30

90

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

NASA Astrophysics Data System (ADS)

The lead ruthenate pyrochlore Pb 2Ru 2O 6,5, in both high- and low-area forms, has been characterized using thermogravimetric analysis, X-ray photo-electron spectroscopy, X-ray diffraction, cyclic voltammetry, and O 2 reduction and generation kinetic—mechanistic studies. Mechanisms are proposed. Compounds in which part of the Ru is substituted with Ir have also been prepared. They exhibit somewhat better performance for O 2 reduction in porous, gas-fed electrodes than the unsubstituted compound. The anodic corrosion resistance of pyrochlore-based porous electrodes was improved by using two different anionically conducting polymer overlayers, which slow down the diffusion of ruthenate and plumbate out of the electrode The O 2 generation performance was improved with both types of electrodes. With a hydrogel overlayer, the O 2 reduction performance was also improved.

Prakash, Jai; Tryk, Donald; Yeager, Ernest

91

Applications of nanotechnology in water and wastewater treatment  

E-print Network

Applications of nanotechnology in water and wastewater treatment Xiaolei Qu, Pedro J.J. Alvarez and wastewater treatment Water reuse Sorption Membrane processes Photocatalysis Disinfection Microbial control. Nanotechnology holds great potential in advancing water and wastewater treatment to improve treatment efficiency

Alvarez, Pedro J.

92

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

93

Enhanced visible light photocatalysis through fast crystallization of zinc oxide nanorods  

PubMed Central

Summary Hydrothermally grown ZnO nanorods have inherent crystalline defects primarily due to oxygen vacancies that enhance optical absorption in the visible spectrum, opening up possibilities for visible light photocatalysis. Comparison of photocatalytic activity of ZnO nanorods and nanoparticle films on a test contaminant methylene blue with visible light irradiation at 72 kilolux (klx) showed that ZnO nanorods are 12–24% more active than ZnO nanoparticulate films. This can be directly attributed to the increased effective surface area for adsorption of target contaminant molecules. Defects, in the form of interstitials and vacancies, were intentionally created by faster growth of the nanorods by microwave activation. Visible light photocatalytic activity was observed to improve by ?8% attributed to the availability of more electron deficient sites on the nanorod surfaces. Engineered defect creation in nanostructured photocatalysts could be an attractive solution for visible light photocatalysis. PMID:21977391

Baruah, Sunandan; Mahmood, Mohammad Abbas; Myint, Myo Tay Zar; Bora, Tanujjal

2010-01-01

94

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

PubMed

Photovoltaics and photocatalysis are two significant applications of clean and sustainable solar energy, albeit constrained by their inability to harvest the infrared spectrum of solar radiation. Lanthanide-doped materials are particularly promising in this regard, with tunable absorption in the infrared region and the ability to convert the long-wavelength excitation into shorter-wavelength light output through an upconversion process. In this review, we highlight the emerging applications of lanthanide-doped upconversion materials in the areas of photovoltaics and photocatalysis. We attempt to elucidate the fundamental physical principles that govern the energy conversion by the upconversion materials. In addition, we intend to draw attention to recent technologies in upconversion nanomaterials integrated with photovoltaic and photocatalytic devices. This review also provides a useful guide to materials synthesis and optoelectronic device fabrication based on lanthanide-doped upconversion materials. PMID:25397916

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

2014-12-01

95

Photocatalysis and hydrophilicity of doped TiO 2 thin films  

Microsoft Academic Search

TiO2 thin films were prepared using the dip-coating method with a polymeric sol including additives such as Al, W, and Al+W to examine two major properties: photocatalysis and hydrophilicity. W-doped films showed the best photocatalytic efficiency, while Al-doped film was poorer than undoped samples. However, good hydrophilicity in terms of saturation contact angle and surface conversion rate was found in

Young Cheol Lee; Young Pyo Hong; Ha Yong Lee; Hoon Kim; Young Jin Jung; Kyung Hyun Ko; Hyun Seok Jung; Kug Sun Hong

2003-01-01

96

Comparison of the degradations of diphenamid by homogeneous photolysis and heterogeneous photocatalysis in aqueous solution  

Microsoft Academic Search

In this work, the homogeneous and heterogeneous degradations of diphenamid (DPA) in aqueous solution were conducted by direct photolysis with UVC (254nm) and by photocatalysis with TiO2\\/UVA (350nm), and the experimental results were compared. It was found that the homogeneous photolysis by UVC irradiation alone was quite efficient to degrade DPA up to 100% after 360min, but was very inefficient

Hai-chao Liang; Xiang-zhong Li; Yin-hua Yang; Kong-hung Sze

2010-01-01

97

Degradation of nitrogen containing organic compounds by combined photocatalysis and ozonation  

Microsoft Academic Search

The combination of TiO2-assisted photocatalysis and ozonation in the degradation of nitrogen-containing substrates such as alkylamines, alkanolamines, heterocyclic and aromatic N-compounds has been investigated. A laboratory set-up was designed and the influence of the structure of the N-compound, the TiO2 and ozone concentration on the formation of breakdown products were examined. The experimental results showed that a considerable increase in

M. Mare; G. Waldner; R. Bauer; H. Jacobs; J. A. C. Broekaert

1999-01-01

98

Impact of Photocatalysis on Fungal Cells: Depiction of Cellular and Molecular Effects on Saccharomyces cerevisiae.  

PubMed

We have investigated the antimicrobial effects of photocatalysis on the yeast model Saccharomyces cerevisiae. To accurately study the antimicrobial mechanisms of the photocatalytic process, we focused our investigations on two questions: the entry of the nanoparticles in treated cells and the fate of the intracellular environment. Transmission electronic microscopy did not reveal any entry of nanoparticles within the cells, even for long exposure times, despite degradation of the cell wall space and deconstruction of cellular compartments. In contrast to proteins located at the periphery of the cells, intracellular proteins did not disappear uniformly. Disappearance or persistence of proteins from the pool of oxidized intracellular isoforms was not correlated to their functions. Altogether, our data suggested that photocatalysis induces the establishment of an intracellular oxidative environment. This hypothesis was sustained by the detection of an increased level of superoxide ions (O2°(-)) in treated cells and by greater cell cultivability for cells expressing oxidant stress response genes during photocatalytic exposure. The increase in intracellular ROS, which was not connected to the entry of nanoparticles within the cells or to a direct contact with the plasma membrane, could be the result of an imbalance in redox status amplified by chain reactions. Moreover, we expanded our study to other yeast and filamentous fungi and pointed out that, in contrast to the laboratory model S. cerevisiae, some environmental strains are very resistant to photocatalysis. This could be related to the cell wall composition and structure. PMID:25261515

Thabet, Sana; Simonet, France; Lemaire, Marc; Guillard, Chantal; Cotton, Pascale

2014-12-15

99

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

100

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

PubMed

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

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

2014-01-01

101

Ligand-Exchange Assisted Formation of Au/TiO2 Schottky Contact for Visible-Light Photocatalysis.  

PubMed

Plasmonic noble metal nanoparticles have emerged as a promising material in sensitizing wide-bandgap semiconductors for visible-light photocatalysis. Conventional methods in constructing such heterocatalysts suffer from either poor control over the size of the metal nanoparticles or inefficient charge transfer through the metal/semiconductor interface, which limit their photocatalytic activity. To solve this problem, in this work we construct Au/TiO2 photocatalysts by depositing presynthesized colloidal Au nanoparticles with well-controlled sizes to TiO2 nanocrystals and then removing capping ligands on the Au surface through a delicately designed ligand-exchange method, which leads to close Au/TiO2 Schottky contact after a mild annealing process. Benefiting from this unique synthesis strategy, the obtained photocatalysts show superior activity to conventionally prepared photocatalysts in dye decomposition and water-reduction hydrogen production under visible-light illumination. This study not only opens up new opportunities in designing photoactive materials with high stability and enhanced performance for solar energy conversion but also provides a potential solution for the well-recognized challenge in cleaning capping ligands from the surface of colloidal catalyst nanoparticles. PMID:25329925

Ding, Dawei; Liu, Kai; He, Shengnan; Gao, Chuanbo; Yin, Yadong

2014-11-12

102

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

PubMed Central

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

2014-01-01

103

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

Microsoft Academic Search

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

Kristof Demeestere; Jo Dewulf; Herman Van Langenhove

2007-01-01

104

The Adsorption of BiIII/Pt Nanocomposites at Platinum Electrode with Highly Enhanced Electrocatalysis Toward Glucose  

NASA Astrophysics Data System (ADS)

In this paper, we first fabricated a nanoPt modified platinum electrode. Then through a simple method, the electrode surface was introduced with a submonolayer of bismuth that acted as an effective promoter. Cyclic voltammetry and other characterizations were employed. The obtained BiIII/nanoPt/Pt electrode exhibited two greatly increased oxidation peaks at negative and positive potential areas, respectively. The signals were far larger than that of platinum electrode because of the large true surface area of nanoparticles and the catalysis of bismuth adsorbed on platinum. In the presence of bismuth, the platinum active sites could combine with more OH- from bismuth hydroxyl to form a new active site for the oxidation of glucose. The prepared BiIII/nanoPt/Pt electrode given high sensitivity and excellent linearship to glucose detection and showed the potential application in the areas of electrocatalysis or electroanalysis.

Yang, Zhuoyuan; Miao, Yuqing; Wang, Tianrui; Xiao, Mingshu; Liang, Xiaocai; Yang, Yang; Li, Weiwei

2014-05-01

105

Tuning the functionality of a carbon nanofiber-Pt-RuO2 system from charge storage to electrocatalysis.  

PubMed

Chemical-functionalization-induced switching in the property of a hybrid system composed of a hollow carbon nanofiber (CNF) and Pt and RuO(2) nanoparticles from charge storage to electrocatalysis is presented. The results of this study show how important it is to have a clear understanding of the nature of surface functionalities in the processes involving dispersion of more than one component on various substrates including carbon nanomorphologies. When pristine CNF is used to decorate Pt and RuO(2) nanoparticles, random dispersion occurs on the CNF surface (C-PtRuO(2)). This results in mainly phase-separated nanoparticles rich in RuO(2) characteristics. In contrast to this, upon moving from the pristine CNF to those activated by a simple H(2)O(2) treatment to create oxygen-containing surface functional groups, a material rich in Pt features on the surface is obtained (F-PtRuO(2)). This is achieved because of the preferential adsorption of RuO(2) by the functionalized surface of CNF. A better affinity of the oxygen-containing functional groups on CNF toward RuO(2) mobilizes relatively faster adsorption of this moiety, leading to a well-controlled segregation of Pt nanoparticles toward the surface. Further reorganization of Pt nanoparticles leads to the formation of a Pt nanosheet structure on the surface. The electrochemical properties of these materials are initially evaluated using cyclic voltammetric analysis. The cyclic voltammetric results indicate that C-PtRuO(2) shows a charge storage property, a typical characteristic of hydrous RuO(2), whereas F-PtRuO(2) shows an oxygen reduction property, which is the characteristic feature of Pt. This clear switch in the behavior from charge storage to electrocatalysis is further confirmed by galvanostatic charge-discharge and rotating-disk-electrode studies. PMID:22946658

Balan, Beena K; Kurungot, Sreekumar

2012-09-17

106

Photoelectro-synergistic catalysis combined with a FIA system application on determination of chemical oxygen demand  

Microsoft Academic Search

In this paper, photoelectro-synergistic catalysis oxidation of organics in the water on Ti\\/TiO2\\/PbO2 electrode was investigated. The prepared TiO2 film was investigated with Atomic force micrograph (AFM). Furthermore, the results were compared with those obtained from electrocatalysis (EC) and electro-assisted photocatalysis (PC). The method proposed employed photoelectro-synergistic catalysis (PEC), together with flow injection analysis, to determine the chemical oxygen demand

Jiaqing Li; Lei Zheng; Luoping Li; Guoyue Shi; Yuezhong Xian; Litong Jin

2007-01-01

107

Electrochemical enhancement of solar photocatalysis: degradation of endocrine disruptor bisphenol-A on Ti/TiO2 films.  

PubMed

The photoelectrocatalytic oxidation over immobilized Ti/TiO(2) films in the presence of simulated solar light was investigated for the degradation of bisphenol-A (BPA) in water. The catalyst, consisting of 75:25 anatase:rutile, was prepared by a sol-gel method and characterized by cyclic voltammetry, X-ray diffraction and scanning electron microscopy. Experiments were conducted to assess the effect of applied current (0.02-0.32 mA/cm(2)), TiO(2) loading (1.3-9.2 mg), BPA concentration (120-820 ?g/L), initial solution pH (1 and 7.5) and the aqueous matrix (pure water and treated effluent) on BPA photoelectrocatalytic degradation which was monitored by high performance liquid chromatography equipped with a fluorescence detector. The reaction was favored at anodic currents up to 0.04 mA/cm(2) and lower substrate concentrations, but it was hindered by the presence of residual organic matter and radical scavengers (e.g. bicarbonates) in treated effluents. Moreover, a pseudo-first order kinetic model could fit the experimental data well with the apparent reaction constant taking values between 2.9 and 32.4 10(-3)/min. The degradation of BPA by pure photocatalysis or electrochemical oxidation alone was also studied leading to partial substrate removal. In all cases, the contribution of applied potential to photocatalytic degradation was synergistic with the photocatalytic efficiency increasing between 24% and 97% possibly due to a more efficient separation and utilization of the photogenerated charge carriers. The effect of photoelectrocatalysis on the ecotoxic and estrogenic properties of BPA was also evaluated measuring the bioluminescence inhibition of Vibrio fischeri and performing the yeast estrogen screening assay, respectively. PMID:21458019

Frontistis, Zacharias; Daskalaki, Vasileia M; Katsaounis, Alexandros; Poulios, Ioannis; Mantzavinos, Dionissios

2011-04-01

108

K4Nb6O17-derived photocatalysts for hydrogen evolution from water: Nanoscrolls versus nanosheets  

E-print Network

K4Nb6O17-derived photocatalysts for hydrogen evolution from water: Nanoscrolls versus nanosheets as a photocatalyst for methanol dehydrogenation and hydrogen evolution from water under ultraviolet (UV) light. Here Photocatalysis Water splitting Hydrogen a b s t r a c t The layered hexaniobate K4Nb6O17 is known

Osterloh, Frank

109

Molecular hydrogen formation from photocatalysis of methanol on anatase-TiO?(101).  

PubMed

Photocatalysis of methanol (CH3OH) on anatase (A)-TiO2(101) has been investigated using temperature programmed desorption (TPD) method with 266 nm light at low surface temperatures. Experimental results show that CH3OH adsorbs on the A-TiO2(101) surface predominantly in molecular form, with only a small amount of CH3OH in dissociated form. Photocatalytic products, formaldehyde (CH2O) and methyl formate (HCOOCH3), have been detected under 266 nm light irradiation. In addition to H2O formation, H2 product is also observed by TPD spectroscopy. Experimental results indicate that H2 product is formed via thermal recombination of H-atoms on the BBO sites from photocatalysis of CH3OH on the A-TiO2(101) surface, and H2 production on the A-TiO2(101) surface is significantly more efficient than that on the rutile (R)-TiO2(110) surface. PMID:24377390

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

2014-01-15

110

DFT-MD approach to TiO2/liquid interface systems for photocatalysis and dye-sensitised solar cell  

E-print Network

DFT-MD approach to TiO2/liquid interface systems for photocatalysis and dye-sensitised solar cell cell (DSC) on the atomic and electronic scales for the last few years. Our final goal is understanding the equilibrium structures and electronic states at the solid- liquid interfaces Figure 1: Typical reaction

Katsumoto, Shingo

111

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-...

112

A new metal-free carbon hybrid for enhanced photocatalysis.  

PubMed

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

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

2014-10-01

113

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.

114

Treatment of chlorinated solvents by TiO2 photocatalysis and photo-Fenton: influence of operating conditions in a solar pilot plant.  

PubMed

Titanium dioxide photocatalysis (using 20 0mg l(-1) of TiO2), under aerobic and anaerobic conditions, and photo-Fenton (2 and 56 mg l(-1) iron) were applied to the treatment of different NBCS (non-biodegradable chlorinated solvents), such as dichloroethane, dichloromethane and trichloromethane dissolved in water at 50 mg l(-1). All the tests were performed in a 35-l solar pilot plant with compound parabolic collectors (CPCs) under natural illumination. The two solar treatments were compared with attention to chloride release and TOC mineralisation, as the main parameters. Photo-Fenton was found to be the more appropriate treatment for these compounds, assuming volatilisation as a drawback of photocatalytic degradation of NBCS dissolved in water. In this context, several operating parameters related to NBCS degradation, e.g., treatment time, temperature, hydrogen peroxide consumption and volatility of parent compounds are discussed. The correct choice of operating conditions can very often diminish the problem of volatilisation during treatment. PMID:15620730

Rodríguez, S Malato; Gálvez, J Blanco; Rubio, Manuel I Maldonado; Ibáñez, P Fernández; Gernjak, W; Alberola, I Oller

2005-01-01

115

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

116

Heterogeneous photocatalysis of real textile wastewater: evaluation of reaction kinetics and characterization.  

PubMed

Real textile wastewater collected from the cotton dyeing bath of a fabric dyeing and finishing plant was subjected to heterogeneous photocatalysis using Ag(+) doped TiO(2) 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% and 99%, respectively for undiluted, 2 times diluted and 5 times diluted wastewater with Ag(+) doped TiO(2) (2.5 g/L) after UV irradiation for 360 minutes. The COD removal for undiluted, 2 times diluted and 5 times diluted wastewater was 47%, 70% and 92%, respectively under similar conditions. The reaction followed Langmuir-Hinshelwood pseudo first order kinetic model and the data fitted well to polynomial regression analysis. PMID:22871009

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

2012-01-01

117

Direct photocatalysis for organic synthesis by using plasmonic-metal nanoparticles irradiated with visible light.  

PubMed

Recent advances in direct-use plasmonic-metal nanoparticles (NPs) as photocatalysts to drive organic synthesis reactions under visible-light irradiation have attracted great interest. Plasmonic-metal NPs are characterized by their strong interaction with visible light through excitation of the localized surface plasmon resonance (LSPR). Herein, we review recent developments in direct photocatalysis using plasmonic-metal NPs and their applications. We focus on the role played by the LSPR of the metal NPs in catalyzing organic transformations and, more broadly, the role that light irradiation plays in catalyzing the reactions. Through this, the reaction mechanisms that these light-excited energetic electrons promote will be highlighted. This review will be of particular interest to researchers who are designing and fabricating new plasmonic-metal NP photocatalysts by identifying important reaction mechanisms that occur through light irradiation. PMID:25048419

Xiao, Qi; Jaatinen, Esa; Zhu, Huaiyong

2014-11-01

118

TiO2 Photocatalysis Damages Lipids and Proteins in Escherichia coli  

PubMed Central

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

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

2014-01-01

119

Mono- and co-doped NaTaO3 for visible light photocatalysis.  

PubMed

Electronic structures of doped NaTaO3 compounds are of significant interest to visible light photocatalysis. This work involves the study of the band gap, band edge potentials, and thermodynamic stability of certain mono-doped and co-doped NaTaO3 systems, using DFT-PBE as well as hybrid (PBE0) functional calculations. Doping of certain non-magnetic cations (Ti, V, Cu, Zn, W, In, Sn, Sb, Ce, and La), certain anions (N, C, and I), and certain co-dopant pairs (W-Ti, W-Ce, N-I, N-W, La-C, Pb-I, and Cu-Sn) is investigated. Our calculations suggest that substitutional doping of Cu at the Ta site, Cu at the Na site, and C at the O site narrows the band gap of NaTaO3 to 2.3, 2.8, and 2.1 eV, respectively, inducing visible light absorption. Additionally, passivated co-doping of Pb-I and N-W narrows the band gap of NaTaO3 to the visible region, while maintaining the band potentials at favorable positions. Hybrid density of states (DOS) accurately describe the effective band potentials and the location of mid-gap states, which shed light on the possible mechanism of photoexcitation in relation to the photocatalysis reactions. Furthermore, the thermodynamic stability of the doped systems and defect pair binding energies of co-doped systems are discussed in detail. The present results provide useful insights into designing new photocatalysts based on NaTaO3. PMID:24965846

Kanhere, Pushkar; Shenai, Prathamesh; Chakraborty, Sudip; Ahuja, Rajeev; Zheng, Jianwei; Chen, Zhong

2014-08-14

120

subm. to Catalysis Today Challenges in the first-principles description of reactions in electrocatalysis  

E-print Network

and ice- covered Pt(111) [19]. Because of the weak water-metal interaction, the dissociation barrier- tions can contribute to an understanding of the structures and reactions at water/metal interfaces in the presence of wa- ter can be regarded as a superposition of the dissociation barrier on the clean Pt(111

Pfeifer, Holger

121

Degradation of organic dyes via bismuth silver oxide initiated direct oxidation coupled with sodium bismuthate based visible light photocatalysis.  

PubMed

Organic dye degradation was achieved via direct oxidation by bismuth silver oxide coupled with visible light photocatalysis by sodium bismuthate. Crystal violet dye decomposition by each reagent proceeded via two distinct pathways, each involving different active oxygen species. A comparison of each treatment method alone and in combination demonstrated that using the combined methods in sequence achieved a higher degree of degradation, and especially mineralization, than that obtained using either method alone. In the combined process direct oxidation acts as a pretreatment to rapidly bleach the dye solution which substantially facilitates subsequent visible light photocatalytic processes. The integrated sequential direct oxidation and visible light photocatalysis are complementary manifesting a > 100% increase in TOC removal, compared to either isolated method. The combined process is proposed as a novel and effective technology based on one primary material, sodium bismuthate, for treating wastewaters contaminated by high concentrations of organic dyes. PMID:22616904

Yu, Kai; Yang, Shaogui; Liu, Cun; Chen, Hongzhe; Li, Hui; Sun, Cheng; Boyd, Stephen A

2012-07-01

122

Oxidation of 2,4-dichlorophenol and 3,4-dichlorophenol by means of Fe(III)-homogeneous photocatalysis and algal toxicity assessment of the treated solutions.  

PubMed

Chlorophenols are used worldwide as broad-spectrum biocides and fungicides. They have half-life times in water from 0.6 to 550 h and in sediments up to 1700 h and, due to their numerous origins, they can be found in wastewaters, groundwaters or soils. Moreover, chlorophenols are not readily biodegradable. Recently, classic Advanced Oxidation Processes (AOP) have been proposed for their abatement in an aqueous solution. This paper investigates the oxidation of 2,4-dichlorophenol and 3,4-dichlorophenol, at starting concentrations of 6.1 · 10(-5) mol L(-1), in aqueous solutions through Fe(III)/O(2) homogeneous photocatalysis under UV light (303 ÷ 366 nm). The Fe(III)/O(2) homogeneous photocatalysis is less expensive than using H(2)O(2) due to the capability of Fe(III) to produce OH radicals, if irradiated with an UVA radiation, and of oxygen to re-oxidize ferrous ions to ferric ones when dissolved in solution. The results show that the best working conditions, for both compounds, are found for pH=3.0 and initial Fe(III) concentration equal to 1.5 · 10(-4) mol L(-1) although the investigated oxidizing system can be used even at pH close to 4.0 but with slower abatement kinetics. Toxicity assessment on algae indicates that treated solutions of 2,4-dichlorophenol are less toxic on algae Pseudokirchneriella subcapitata if compared to not treated solutions whereas in the case of 3,4-dichlorophenol only the samples collected during the runs at 20 and 60 min are capable of inhibiting the growth of the adopted organism. The values of the kinetic constant for the photochemical re-oxidation of iron (II) to iron (III) and for HO attack to intermediates are evaluated by a mathematical model for pH range of 2.0-3.0 and initial Fe(III) concentrations range of 1.5 · 10(-5)-5.2 · 10(-4) mol L(-1). PMID:21251692

Andreozzi, Roberto; Di Somma, Ilaria; Marotta, Raffaele; Pinto, Gabriele; Pollio, Antonino; Spasiano, Danilo

2011-02-01

123

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

124

NF-TiO? photocatalysis of amitrole and atrazine with addition of oxidants under simulated solar light: emerging synergies, degradation intermediates, and reusable attributes.  

PubMed

In order to investigate sustainable alternatives to current water treatment methods, the effect of NF-titania film thickness and subsequent photocatalysis in combination with oxidants was examined under simulated solar light. Such a combination presents a theoretical possibility for a synergistic interaction between the photocatalyst and the oxidant (activation of the oxidant by the catalyst under conditions under which it may not conventionally be activated). To investigate, peroxymonosulfate (PMS) and persulfate (PS) were used as oxidants, and two pesticides, amitrole and atrazine, were used as target contaminants. In the absence of a film, activation of PMS under simulated solar conditions is demonstrated by removal of atrazine, whereas PS provided minimal removal, suggesting inefficient activation. Combining photocatalytic films with PMS and PS manifested synergies for both oxidants. The effect was most pronounced for PS since PMS already underwent significant activation without the photocatalyst. Amitrole degradation results indicated a lack of removal of amitrole by activated PS alone, suggesting that this sulfate radical-based treatment technology may be ineffective for the removal of amitrole. The NF-TiO? films demonstrated reusability under solar light both with and without oxidants. Finally, the degradation intermediates were analyzed, and a new intermediate appeared upon incorporating oxidants into the system. PMID:23811632

Andersen, Joel; Pelaez, Miguel; Guay, Lisa; Zhang, Zhaohong; O'Shea, Kevin; Dionysiou, Dionysios D

2013-09-15

125

Isolation of hydrogen from water and\\/or artificial seawater by sonophotocatalysis using alternating irradiation method  

Microsoft Academic Search

Sonophotocatalysis means photocatalysis with ultrasonic irradiation. Hydrogen and oxygen were obtained from water under argon atmosphere by sonophotocatalysis and each product was isolated using alternating irradiation method. This method involves irradiation in turn with ultrasound and light. Hydrogen was also isolated from sodium chloride solution, like seawater, using a similar technique. However, the ratio of products from NaCl solution was

Hisashi Harada

2001-01-01

126

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 ...

127

The investigation of the LED-activated FeFNS-TiO2 nanocatalyst for photocatalytic degradation and mineralization of organophosphate pesticides in water.  

PubMed

This study evaluated the preparation and characterization of an efficient doped TiO2 as a novel catalyst for degradation of diazinon model pesticide using LED-activated photocatalysis. TiO2 was doped using N, NS, FeNS, and FeFNS. The FeFNS-doped TiO2 showed the highest catalytic activity in LED/photocatalysis. FeFNS-doped TiO2 is a mesoporous nanocrystal powder with a mean pore diameter of 10.2 nm, a specific surface area of 104.4 m(2)/g and a crystallite size of 6.7 nm. LED/photocatalysis using FeFNS-doped TiO2 improved diazinon degradation by 52.3% over that of as-made plain TiO2 at an optimum solution pH of 7. The diazinon degradation in LED/photocatalysis using FeFNS-doped TiO2 increased from 44.8% to 96.3% when the catalyst concentration increased from 25% to 300%at a reaction time of 100 min. The degradation and mineralization of diazinon during LED/photocatalysis with FeFNS-doped TiO2 catalyst followed the pseudo-first-order reaction model with the rate constants of 0.973 h(-1) and 0.541 h(-1), respectively. The FeFNS-doped TiO2 was found to be an efficient catalyst that was photoactivated using UV-LED lamps. LED/photocatalysis with FeFNS-doped TiO2 catalyst is a promising alternative to conventional UV/TiO2photocatalysis for producing free OH radicals for use in the degradation and mineralization of water toxic contaminants. PMID:24793111

Hossaini, Hiwa; Moussavi, Gholamreza; Farrokhi, Mehrdad

2014-08-01

128

Nanoscale nickel oxide/nickel heterostructures for active hydrogen evolution electrocatalysis  

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

129

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

130

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

131

Degradation of diclofenac sodium using combined processes based on hydrodynamic cavitation and heterogeneous photocatalysis.  

PubMed

Diclofenac sodium, a widely detected pharmaceutical drug in wastewater samples, has been selected as a model pollutant for degradation using novel combined approach of hydrodynamic cavitation and heterogeneous photocatalysis. A slit venturi has been used as cavitating device in the hydrodynamic cavitation reactor. The effect of various operating parameters such as inlet fluid pressure (2-4 bar) and initial pH of the solution (4-7.5) on the extent of degradation have been studied. The maximum extent of degradation of diclofenac sodium was obtained at inlet fluid pressure of 3 bar and initial pH as 4 using hydrodynamic cavitation alone. The loadings of TiO2 and H2O2 have been optimised to maximise the extent of degradation of diclofenac sodium. Kinetic study revealed that the degradation of diclofenac sodium fitted first order kinetics over the selected range of operating protocols. It has been observed that combination of hydrodynamic cavitation with UV, UV/TiO2 and UV/TiO2/H2O2 results in enhanced extents of degradation as compared to the individual schemes. The maximum extent of degradation as 95% with 76% reduction in TOC has been observed using hydrodynamic cavitation in conjunction with UV/TiO2/H2O2 under the optimised operating conditions. The diclofenac sodium degradation byproducts have been identified using LC/MS analysis. PMID:24262760

Bagal, Manisha V; Gogate, Parag R

2014-05-01

132

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

133

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

PubMed

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

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

2014-08-01

134

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

PubMed

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

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

2014-01-01

135

Dramatic activities of vanadate intercalated bismuth doped LDH for solar light photocatalysis.  

PubMed

To harvest solar energy efficiently, a series of Zn/Bi layered double hydroxide (LDH) photocatalysts with different molar ratios of Zn/Bi (2?:?1, 3?:?1, 4?:?1) has been synthesized by a coprecipitation method at constant pH. All the Bi doped LDH samples displayed hydrotalcite-like structure with interlayer carbonate, in which crystallinity decreases as the bismuth content increases. The Zn/Bi (4?:?1) LDH with a small amount of bismuth in the brucite layer and possessing high crystallinity was further modified hydrothermally by intercalating decavanadate and it showed high photochemical stability and photocatalytic activity for the degradation of different organic pollutants for practical applications under solar light irradiation. The structural integrity of the materials has been successfully characterized by studying their structural, morphological, electronic and optical properties by various physico-chemical techniques. The present study provided an insight into oxo-bridged MMCT of the LDH and established that the Zn(II)-O-Bi(III) units resulted in the generation of superoxide radicals which is clearly observed by the EPR technique. The ?OH radicals formed during photocatalysis were revealed by means of the terephthalic acid fluorescence probe method. The photoelectrochemical measurement confirmed that the intercalated vanadate anion was crucial to obtain an optimal synergistic effect for the degradation of organic pollutants. The prolonged lifetime of photogenerated charges and improved charge transfer capability were confirmed by time-resolved fluorescence emission spectra. Furthermore, a detailed mechanism for the enhanced photocatalytic activity was discussed. PMID:25005613

Mohapatra, Lagnamayee; Parida, K M

2014-08-28

136

The Photocatalysis of N,N-diethyl-m-toluamide (DEET) Using Dispersions of Degussa P-25 TiO2 Particles  

EPA Science Inventory

The photocatalysis of N,N-diethyl-meta-toluamide (DEET) was examined using aqueous Degussa P-25 TiO2 dispersions and a 350 nm high pressure Hg lamp UV reactor. Various concentrations of humic acid (HA) were added to the photocatalytic sample matrix in order to simulat...

137

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

PubMed

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

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

2006-12-01

138

Photocatalytic degradation of amoxicillin, ampicillin and cloxacillin antibiotics in aqueous solution using UV\\/TiO 2 and UV\\/H 2O 2\\/TiO 2 photocatalysis  

Microsoft Academic Search

Degradation of amoxicillin, ampicillin and cloxacillin antibiotics in aqueous solution by TiO2 photocatalysis under UVA (365nm) irradiation was studied. Enhancement of photocatalysis by addition of H2O2 was also evaluated. The results showed that no significant degradation occurred by 300-min UVA irradiation per se and pH had a great effect on antibiotic degradation. Photocatalytic reactions approximately followed a pseudo-first order kinetics

Emad S. Elmolla; Malay Chaudhuri

2010-01-01

139

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

2013-10-01

140

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

PubMed Central

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

2013-01-01

141

Photocatalytic degradation of bezacryl yellow in batch reactors - feasibility of the combination of photocatalysis and a biological treatment.  

PubMed

A combined process coupling photocatalysis and a biological treatment was investigated for the removal of Bezacryl yellow (BZY), an industrial-use textile dye. Photocatalytic degradation experiments of BZY were carried out in two stirred reactors, operating in batch mode with internal or external irradiation. Two photocatalysts (TiO2P25 and TiO2PC500) were tested and the dye degradation was studied for different initial pollutant concentrations (10-117 mg L(-1)). A comparative study showed that the photocatalytic degradation led to the highest degradation and mineralization yields in a stirred reactor with internal irradiation in the presence of the P25 catalyst. Regardless of the photocatalyst, discoloration yields up to 99% were obtained for 10 and 20 mg L(-1) dye concentrations in the reactor with internal irradiation. Moreover, the first-order kinetic and Langmuir-Hinshelwood models were examined by using the nonlinear method for different initial concentrations and showed that the two models lead to completely different predicted kinetics suggesting that they were completely different.According to the BOD5/ Chemical oxygen demand (COD) ratio, the non-treated solution (20 mg L(-1) of BZY) was estimated as non-biodegradable. After photocatalytic pretreatment of bezacryl solution containing 20 mg/L of initial dye, the biodegradability test showed a BOD5/COD ratio of 0.5, which is above the limit of biodegradability (0.4). These results were promising regarding the feasibility of combining photocatalysis and biological mineralization for the removal of BZY. PMID:25409577

Khenniche, Lamia; Favier, Lidia; Bouzaza, Abdelkrim; Fourcade, Florence; Aissani, Farida; Amrane, Abdeltif

2015-01-01

142

New insights into electrocatalysis based on plasmon resonance for the real-time monitoring of catalytic events on single gold nanorods.  

PubMed

Gold nanoparticles (GNPs) have been widely applied in industrial catalysis and electrocatalysis. Owing to their wide variety of shapes, sizes, and compositions, a range of different catalytic properties is possible. Thus, it is important to monitor catalytic processes and their mechanisms on single GNP surfaces to avoid averaging effects in bulk systems. Therefore, a novel method based on dark-field scattering spectroscopy was developed to monitor, in real-time, the electrocatalytic oxidation of hydrogen peroxide on a single gold nanoparticle surface. The catalytic mechanism was revealed via the plasmon resonance scattering spectral shift of single gold nanorod with the elimination of bulk effect. Moreover, we found that the presence of chloride ions could block the catalytic activity of nanorods for the oxidation of H2O2. Most importantly, it was discovered that individual nanoparticles have variable properties with different spectra shifts during the catalytic process. The obtained optical signals from individual nanorods not only offer versatile information regarding the reaction but also improve the understanding of electrochemistry and the catalysis mechanism of single nanoparticles. PMID:24766541

Jing, Chao; Rawson, Frankie James; Zhou, Hao; Shi, Xin; Li, Wen-Hui; Li, Da-Wei; Long, Yi-Tao

2014-06-01

143

Synergy of photocatalysis and adsorption for simultaneous removal of Cr(VI) and Cr(III) with TiO? and titanate nanotubes.  

PubMed

An one-step efficient simultaneous removal of Cr(VI) and Cr(III) was achieved with mixture of TiO? and titanate nanotubes (TNTs). Unlike the conventional two-step Cr removal with a first photocatalytic reduction of Cr(VI) and a subsequent adsorption of Cr(III), the proposed single process significantly reduced reaction time (over 50%). The synergy of photocatalysis and adsorption played an important role in enhancing Cr removal process. The synergetic mechanism was interpreted and indirectly confirmed with H?O? variation during photocatalysis. The instant transfer of the reduced Cr from TiO? surface to TNTs interlayer greatly promoted the release of photocatalytic sites of TiO?, which in turn considerably enhanced photocatalytic activity of TNTs by inhibiting electron-hole pairs recombination. The optimum condition for the whole process was at pH 5. Adsorption of Cr(III) was primarily in the interlayer of TNTs at pH ? 5. However, higher pH would lead to precipitation of Cr(OH)? onto TNTs as observed by X-ray photoelectron spectroscopy (XPS). Addition of Ca(2+) could promoted photocatalysis owing to its ionic bridging function and form of ?TiOH(+)-Cr(VI)-Ca(2+)-Cr(VI) linkages, while SO?(2-) only slightly inhibited photo-reduction of Cr(VI), indicating good synergy of photocatalysis and adsorption even at high ionic strength of electrolyte. Besides, the desorbed TNTs could be easily regenerated by remedying the damaged tubular structure and reused for Cr removal with excellent performance. The outstanding synergetic effects with essential explanation of the mechanism make this study not only fundamentally important but also potentially practical applicable. PMID:24486715

Liu, Wen; Ni, Jinren; Yin, Xiaochen

2014-04-15

144

Coupling of solar photoelectro-Fenton with a BDD anode and solar heterogeneous photocatalysis for the mineralization of the herbicide atrazine.  

PubMed

Here, the synergetic effect of coupling solar photoelectro-Fenton (SPEF) and solar heterogeneous photocatalysis (SPC) on the mineralization of 200mL of a 20mg L(-1) atrazine solution, prepared from the commercial herbicide Gesaprim, at pH 3.0 was studied. Uniform, homogeneous and adherent anatase-TiO2 films onto glass spheres of 5mm diameter were prepared by the sol-gel dip-coating method and used as catalyst for SPC. However, this procedure yielded a poor removal of the substrate because of the low oxidation ability of positive holes and OH formed at the catalyst surface to destroy it. Atrazine decay was improved using anodic oxidation (AO), electro-Fenton (EF), SPEF and coupled SPEF-SPC at 100mA. The electrolytic cell contained a boron-doped diamond (BDD) anode and H2O2 was generated at a BDD cathode fed with an air flow. The removal and mineralization of atrazine increased when more oxidizing agents were generated in the sequence AOwater oxidation at the BDD anode in AO, along with OH formed from Fenton's reaction between added Fe(2+) and generated H2O2 in EF. In SPEF, solar radiation produced higher amounts of OH induced from the photolysis of Fe(III) species and photodecomposed intermediates like Fe(III)-carboxylate complexes. The synergistic action of sunlight in the most potent coupled SPEF-SPC was ascribed to the additional quick removal of several intermediates with the oxidizing agents formed at the TiO2 surface. After 300min of this treatment, 80% mineralization, 9% mineralization current efficiency and 1.93kWhg(-1) TOC energy cost were obtained. The mineralization of atrazine was inhibited by the production of cyanuric acid, which was the main byproduct detected at the end of the coupled SPEF-SPC process. PMID:24231044

Garza-Campos, Benjamín R; Guzmán-Mar, Jorge Luis; Reyes, Laura Hinojosa; Brillas, Enric; Hernández-Ramírez, Aracely; Ruiz-Ruiz, Edgar J

2014-02-01

145

A practical demonstration of water disinfection using TiO 2 films and sunlight  

Microsoft Academic Search

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

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

2006-01-01

146

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 ...

147

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.

148

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

149

COD removal and toxicity decrease from tannery wastewater by zinc oxide-assisted photocatalysis: a case study.  

PubMed

This work reports the optimization of degradation conditions and toxicity decrease in the tannery wastewater, collected in the retanning and dyeing steps. This effluent was filtered, diluted in a 1:200 proportion, and investigated as a case study on a bench scale by heterogeneous photocatalysis. These conditions were attained when the suspension, containing 1 g L-1 of ZnO and effluent, was irradiated for 4h at pH 8.0 and 30 degrees C. Physico-chemical parameters such as chemical oxygen demand (COD) decreased from 15,023 to 350 mg O2 L-1; fifth-day biochemical oxygen demand (BODs) from 4374 to 10 mg O2 L-1; total solids from 28,500 to 188 mg L-1; total organic carbon (TOC) from 4685 to 4.93 mg L-1, and turbidity from 331 to 1.15NTU after 4h of irradiation. The LC50 increase from 14.90% to 56.82% in the lethality assay of Artemia salina L. microcrustacean as well as the dissolved oxygen of 6.45mg L-1 indicated efficiency in this treatment. PMID:24956748

Hasegawa, Maria Claudia; Daniel, Juliana Feijó de Souza; Takashima, Keiko; Batista, Gisselma A; da Silva, Sandra M C P

2014-08-01

150

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

151

Improvement of gaseous pollutant photocatalysis with WO3/TiO2 heterojunctional-electrical layered system.  

PubMed

Since the photogenerated holes play a much more important role than electrons in gas-phase photocatalysis, it is better to enrich the holes in the surface of a material system. Here, a novel [interdigital electrode/WO(3)/TiO(2)] heterojunctional-electrical layered (HEL) system is proposed to realize this attempt. The HEL system consists of interdigital electrode, WO(3) layer and TiO(2) layer, and they are orderly printed onto the alumina substrate from bottom to top using the technology of screen printing. It is surprise that the synergistic effect of layered heterojunction and external low bias can strengthen the separation of electron-hole pairs in both TiO(2) and WO(3), and enrich the TiO(2) surface layer with photogenerated holes to degrade the gaseous pollutants. In comparison with the pure TiO(2) film, a 6-fold enhancement in photocatalytic activity was observed using the HEL system by applying a very low bias of 0.2V. Furthermore, the results also showed that the remarkable improvement could not be obtained when either the WO(3) layer or the low external bias was absent. PMID:21924831

Liu, Yuan; Xie, Changsheng; Li, Huayao; Chen, Hao; Zou, Tao; Zeng, Dawen

2011-11-30

152

Heterogeneous photocatalysis of aromatic and chlorinated volatile organic compounds (VOCs) for non-occupational indoor air application.  

PubMed

The current study evaluated the technical feasibility of applying TiO2 photocatalysis to the removal of low-ppb concentrations of volatile organic compounds (VOCs) commonly associated with non-occupational indoor air quality issues. A series of experiments was conducted to evaluate five parameters (relative humidity (RH), hydraulic diameter (HD), feeding type (FT) for VOCs, photocatalytic oxidation (PCO) reactor material (RM), and inlet port size (IPS) of PCO reactor) in relation to the PCO destruction efficiencies of the selected target VOCs. None of the target VOCs exhibited any significant dependence on the RH, which is inconsistent with a previous study where, under conditions of low humidity and a ppm toluene inlet level, a drop in the PCO efficiency was reported with a decreasing humidity. However, the other four parameters (HD, RM, FT, and IPS) were found to be important for better VOC removal efficiencies as regards the application of TiO2 photocatalytic technology for cleansing non-occupational indoor air. The PCO destruction of VOCs at concentrations associated with non-occupational indoor air quality issues was up to nearly 100%, and the CO generated during PCO was a negligible addition to indoor CO levels. Accordingly, a PCO reactor would appear to be an important tool in the effort to improve non-occupational indoor air quality. PMID:15488917

Jo, Wan-Kuen; Park, Kun-Ho

2004-11-01

153

Water  

NSDL National Science Digital Library

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

Ptv, Idaho

2011-10-06

154

C60 aminofullerene-magnetite nanocomposite designed for efficient visible light photocatalysis  

E-print Network

recyclable photosensitizing system for harnessing solar energy for water treatment and disinfection) as a magnetically separable host. Rapid degradation of furfuryl alcohol (FFA) (a singlet oxygen (1 O2) probe) under treatment and disinfection processes is limited owing to the surface hydro- phobicity of C60 [8]. Strategies

Alvarez, Pedro J.

155

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

NASA Astrophysics Data System (ADS)

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 [PdCl 4] 2- and [PtCl 6] 2- that upon reduction transform to corresponding metal nanoparticles. The nanoparticles strongly adhere to Pdop layer and can be used for the electrooxidation of haydrazine and methanol, respectively. Compared to Pd and Pt supported on unmodified MWCNTs, the Pd and Pt nanoparticle decorated on MWCNTs@Pdop exhibit much higher electrocatalytic activity and enhanced stability.

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

2010-09-01

156

Water  

MedlinePLUS

... older adults to drink plenty of liquids, including water, and how to make healthy choices. Here's a Tip "But I Don’t Feel Thirsty" With age, you might lose some of your sense of thirst. To further complicate matters, some medicines might make it even more important ...

157

Photocatalytic degradation of PCP-Na with TiO2 photocatalysis loaded with platinum.  

PubMed

Titanium dioxide (TiO2) samples of different crystal forms were prepared by hydrolysis tetrabutyl titanate in various water to alkoxide ratios and sintering the hydrolysis product at different temperatures. The photocatalysts coated on hollow glass beads and loaded with platinum varying from 0.2% to 2.4% by weight. The photocatalytic degradation rate of sodium pentachlorophenolate (PCP-Na) depends on the preparing conditions such as: sintering temperatures, water to alkoxide ratios (R), platinum content and the size. The proper conditions of preparation photocatalysts are as follows: the ratio of TiO2: sodium silicate: hollow glass beads: platinum is 10:5:20:0.15 (w/w), R is 100, sintering temperature is 650 degrees C, and the size of hollow glass is 0.5-1 mm. Under these conditions, the ratio between acatase and rutile of the photocatalyst is 2:1, and the photocatalytic activity is high. PMID:12211998

Xi, Bei-Dou; Liu, Hong-Liang

2002-07-01

158

Degradation of paracetamol in aqueous solutions by TiO 2 photocatalysis  

Microsoft Academic Search

In this study, photo\\/photocatalytic oxidation of common analgesic and antipyretic drug, paracetamol (acetaminophen), was investigated to determine the optimal operating conditions for degradation in water. UVA (365nm) radiation alone degraded negligible amount of paracetamol, whereas paracetamol concentration decreased substantially under an irradiation of UVC (254nm) with marginal changes in total organic carbon (TOC). In the presence of TiO2, much faster

Liming Yang; Liya E. Yu; Madhumita B. Ray

2008-01-01

159

Stepwise photocatalytic dissociation of methanol and water on TiO2(110).  

PubMed

We have investigated the photocatalysis of partially deuterated methanol (CD(3)OH) and H(2)O on TiO(2)(110) at 400 nm using a newly developed photocatalysis apparatus in combination with theoretical calculations. Photocatalyzed products, CD(2)O on Ti(5c) sites, and H and D atoms on bridge-bonded oxygen (BBO) sites from CD(3)OH have been clearly detected, while no evidence of H(2)O photocatalysis was found. The experimental results show that dissociation of CD(3)OH on TiO(2)(110) occurs in a stepwise manner in which the O-H dissociation proceeds first and is then followed by C-D dissociation. Theoretical calculations indicate that the high reverse barrier to C-D recombination and the facile desorption of CD(2)O make photocatalytic methanol dissociation on TiO(2)(110) proceed efficiently. Theoretical results also reveal that the reverse reactions, i.e, O-H recombination after H(2)O photocatalytic dissociation on TiO(2)(110), may occur easily, thus inhibiting efficient photocatalytic water splitting. PMID:22794088

Guo, Qing; Xu, Chenbiao; Ren, Zefeng; Yang, Wenshao; Ma, Zhibo; Dai, Dongxu; Fan, Hongjun; Minton, Timothy K; Yang, Xueming

2012-08-15

160

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

161

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

PubMed

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 (R(2)=0.947 and Adj-R(2)=0.906, R(2)=0.977 and Adj-R(2)=0.960 and R(2)=0.982 and Adj-R(2)=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. PMID:23659949

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

2013-08-01

162

Impact of metal ions in porphyrin-based applied materials for visible-light photocatalysis: key information from ultrafast electronic spectroscopy.  

PubMed

Protoporphyrin?IX-zinc oxide (PP-ZnO) nanohybrids have been synthesized for applications in photocatalytic devices. High-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and steady-state infrared, absorption, and emission spectroscopies have been used to analyze the structural details and optical properties of these nanohybrids. Time-resolved fluorescence and transient absorption techniques have been applied to study the ultrafast dynamic events that are key to photocatalytic activities. The photocatalytic efficiency under visible-light irradiation in the presence of naturally abundant iron(III) and copper(II) ions has been found to be significantly retarded in the former case, but enhanced in the latter case. More importantly, femtosecond (fs) transient absorption data have clearly demonstrated that the residence of photoexcited electrons from the sensitizer PP in the centrally located iron moiety hinders ground-state bleach recovery of the sensitizer, affecting the overall photocatalytic rate of the nanohybrid. The presence of copper(II) ions, on the other hand, offers additional stability against photobleaching and eventually enhances the efficiency of photocatalysis. In addition, we have also explored the role of UV light in the efficiency of photocatalysis and have rationalized our observations from femtosecond- to picosecond-resolved studies. PMID:25044047

Kar, Prasenjit; Sardar, Samim; Alarousu, Erkki; Sun, Jingya; Seddigi, Zaki S; Ahmed, Saleh A; Danish, Ekram Y; Mohammed, Omar F; Pal, Samir Kumar

2014-08-11

163

[Tetrabutyl titanate hydrolysis prepared TiO2 photocatalysis loaded with platinum technology].  

PubMed

Photocatalysts Pt/TiO2 coated on hollow glass beads were prepared by tetrabutyl titanate hydrolysis with Sodium silicate on hollow glass beads at various condition and loaded with platinum varying from 0.2% to 2.4% by weight. Sodium pentachlorophenolate (PCP-Na) solution were used to examined for their photoactivity and characterized by X-ray and BET. The results indicated that the optimization condition to prepare photocatalysts: Water to titanium alkoxides was 100, Sintering temperature was 650 degrees C, Diameter of hollow glass beads was 0.5 mm, TiO2: sodium silicate: hollow glass beads was 10:2.5:20, Platinum content of photocatalysts was about 1.4%-1.6%. When the experiments were carried out in such conditions, the initial concentration of PCP-Na was 100 mg/L, initial pH was 6.5, oxygen flux was 1.6 mL/s, illumination intensity was 30 kW.m-2, catalysts was 2 g/L, illumination time was 2 hours, respectively. Then the rates removals of PCP-Na could reach 92.0%. PMID:11987410

Xi, Beidou; Liu, Hongliang

2002-01-30

164

Topotactic growth, selective adsorption, and adsorption-driven photocatalysis of protonated layered titanate nanosheets.  

PubMed

Layered titanates with selective adsorption ability and adsorption-driven photocatalytic property can be quite attractive due to their potential applications in water purification. In this work, lepidocrocite-like layered protonated titanate (H2Ti2O5·H2O, denoted as HTO) nanosheets were successfully synthesized by an ion-exchange process. It turns out that this layered structure displays an abundant and selective adsorption toward the fluoroquinolone pharmaceutical compared with some large dye molecules due to a size selectivity of the interlayer spacing of HTO and the molecular horizontal size, as well as their electrostatic interaction. The uptake ability of HTO could be readily controlled through adjusting the pH values of adsorbate solution, and the maximum uptake capacity was achieved at the pH value of about 5.5 for ciprofloxacin (CIP) and 6.5 for moxifloxacin (MOX). The adsorption amount of smaller nalidixic acid (NAL) showed an increasing tendency as the pH value decreased. Moreover, the two-dimensional layered crystal structure also permits such HTO nanosheets to have a large percentage of (010) faces exposed, which is considerably provided by the interlayer surfaces of these nanosheets. The (010) surface has a similar Ti and O atomic arrangement as to the highly reactive anatase TiO2(001) one. Due to these specific characteristics, these HTO nanosheets show excellent photocatalytic activity in degrading CIP under UV light irradiation as well as possess a superior adsorption ability to remove CIP from aqueous solution selectively and efficiently. The photocatalytic reaction is believed to be mainly conducted on the active anatase (001)-like interlayer (010) surfaces of the layered structures since the as-prepared HTO performs an adsorption-driven molecular recognitive photocatalytic reaction. PMID:25233252

Wu, Qili; Yang, Xianfeng; Liu, Jia; Nie, Xin; Huang, Yongliang; Wen, Yuping; Khan, Javid; Khan, Wasim U; Wu, Mingmei; An, Taicheng

2014-10-22

165

SnO2@CdS nanowire-quantum dots heterostructures: tailoring optical properties of SnO2 for enhanced photodetection and photocatalysis  

NASA Astrophysics Data System (ADS)

Rationally designed SnO2@CdS nanowire-quantum dots (QDs) heterostructures were realized by a wet-chemical method via hydroxide cluster growth mechanism on high crystalline quality SnO2 nanowires, which were synthesized by a vapor transport method. The heterostructures showed enhanced photon harvesting capability and photodetection sensitivity at visible regime than that of wide band gap homogeneous SnO2 nanowires, as characterized by UV-Vis absorption and photoconductivity measurements. In addition, the SnO2@CdS nanowire-QDs heterostructures showed enhanced photocatalytic activity by more than 109% in a conceptual demonstration of photodegradation of methylene blue solution. Our results suggest that the SnO2@CdS nanowire-QDs heterostructures exhibit considerable promise for highly sensitive visible-light photodetectors and highly efficient photocatalysis.

Pan, Jun; Li, Jiangtian; Yan, Zilai; Zhou, Banghong; Wu, Hanshuo; Xiong, Xiang

2013-03-01

166

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 Tisbnd Osbnd N and Tisbnd Nsbnd O 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

167

Field performance test of an air-cleaner with photocatalysis-plasma synergistic reactors for practical and long-term use.  

PubMed

A practical and long-term usable air-cleaner based on the synergy of photocatalysis and plasma treatments has been developed. A field test of the air-cleaner was carried out in an office smoking room. The results were compared to previously reported laboratory test results. Even after a treatment of 12,000 cigarettes-worth of tobacco smoke, the air-cleaner maintained high-level air-purification activity (98.9% ± 0.1% and 88% ± 1% removal of the total suspended particulate (TSP) and total volatile organic compound (TVOC) concentrations, respectively) at single-pass conditions. Although the removal ratio of TSP concentrations was 98.6% ± 0.2%, the ratio of TVOC concentrations was 43.8% after a treatment of 21,900 cigarettes-worth of tobacco smoke in the field test. These results indicate the importance of suitable maintenance of the reactors in the air-cleaner during field use. PMID:25356565

Ochiai, Tsuyoshi; Ichihashi, Erina; Nishida, Naoki; Machida, Tadashi; Uchida, Yoshitsugu; Hayashi, Yuji; Morito, Yuko; Fujishima, Akira

2014-01-01

168

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

NASA Technical Reports Server (NTRS)

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

Underwood, Lauren; Ryan, Robert E.

2007-01-01

169

Interplay between Water and TiO2 Anatase (101) Surface with Subsurface Oxygen Vacancy  

NASA Astrophysics Data System (ADS)

The interaction between water and the TiO2 anatase (101) surface with a subsurface VO is studied using first-principles calculations. Upon water adsorption, the relative stability of the subsurface and surface VO reverses. The surface VO becomes energetically more stable than its subsurface counterpart, which induces VO to migrate from the subsurface to the surface with a very low energy barrier. Then the adsorbed water molecule can easily dissociate through a barrierless pathway facilitated by surface VO. This reaction pathway has a similar energy barrier with another pathway under which water dissociates with the presence of subsurface VO followed by VO migration from the subsurface layer to the surface layer, indicating that subsurface VO can facilitate water dissociation directly, or, via surface VO indirectly. This novel interplay between the adsorbate and substrate defects may provide a new way to explain the origin of the activity of anatase (101) in photocatalysis in aqueous surroundings.

Li, Yadong; Gao, Yi

2014-05-01

170

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

NASA Technical Reports Server (NTRS)

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

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

2014-01-01

171

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

2011-10-01

172

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

Microsoft Academic Search

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

Robyn Obert; Bakul C. Dave

1999-01-01

173

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

SciTech Connect

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

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

2011-01-01

174

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

PubMed

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

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

2014-04-15

175

Photocatalysis: effect of light-activated nanoscale formulations of TiO(2) on Xanthomonas perforans and control of bacterial spot of tomato.  

PubMed

Protection of crops from bacterial diseases presents a continuing challenge, mandating the development of novel agents and approaches. Photocatalysis is a process where chemically reactive oxygen species are catalytically generated by certain minerals in the presence of light. These reactive oxygen species have the capacity to destroy organic molecular structures critical to pathogen viability. In this study, the antibacterial potential of photocatalytic nanoscale titanium dioxide (TiO(2)), nanoscale TiO(2) doped (incorporation of other materials into the structure of TiO(2)) with silver (TiO(2)/Ag), and nanoscale TiO(2) doped with zinc (TiO(2)/Zn; AgriTitan) was evaluated against Xanthomonas perforans, the causal agent for bacterial spot disease of tomato. In vitro experiments on photocatalytic activity and dose dependency were conducted on glass cover slips coated with the nanoscale formulations by adding a known population of X. perforans strain Xp-F7 and illuminating the cover slips under a visible light source. TiO(2)/Ag and TiO(2)/Zn had high photocatalytic activity against X. perforans within 10 min of exposure to 3 × 10(4) lux. Greenhouse studies on naturally and artificially infected transplants treated with TiO(2)/Zn at ?500 to 800 ppm significantly reduced bacterial spot severity compared with untreated and copper control. Protection was similar to the grower standard, copper + mancozeb. The use of TiO(2)/Zn at ?500 to 800 ppm significantly reduced disease incidence in three of the four trials compared with untreated and copper control, and was comparable to or better than the grower standard. The treatments did not cause any adverse effects on tomato yield in any of the field trials. PMID:23190116

Paret, Mathews L; Vallad, Gary E; Averett, Devron R; Jones, Jeffrey B; Olson, Stephen M

2013-03-01

176

Preparation and band gap shift of nano-structured metal oxides and their activity in disinfection of water using laser induced photo-catalysis  

Microsoft Academic Search

Nano structured metal oxides (WO3 and ZnO) were synthesized and impregnated with a noble metal palladium and it was found from the absorption spectra that the band gap energies of the palladium doped material revealed blue shifts compared to the band gap energies of their pure counterparts. Pure and doped material synthesized were used as a photo-catalyst in the presence

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

2011-01-01

177

Preparation of SrTi 0.1Fe 0.9O 3? ? and its photocatalysis activity for degradation of methyl orange in water  

Microsoft Academic Search

Magnetic perovskite-type SrTi0.1Fe0.9O3?? was synthesized by stearic acid gel combustion method. The obtained powders were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), vibrating sample magnetometer (VSM) and UV-Visible absorption spectrum techniques. Mean valence of Fe ion and the concentration of oxygen vacancies in SrTi0.1Fe0.9O3?? were measured by iodometric method. The magnetic properties of

Hong-Xia Chen; Zhi-Xian Wei; Yan Wang; Wei-Wei Zeng; Cai-Mei Xiao

2011-01-01

178

Electrochemical enhancement of solar photocatalysis: Degradation of endocrine disruptor bisphenol-A on Ti\\/TiO 2 films  

Microsoft Academic Search

The photoelectrocatalytic oxidation over immobilized Ti\\/TiO2 films in the presence of simulated solar light was investigated for the degradation of bisphenol-A (BPA) in water. The catalyst, consisting of 75:25 anatase:rutile, was prepared by a sol-gel method and characterized by cyclic voltammetry, X-ray diffraction and scanning electron microscopy. Experiments were conducted to assess the effect of applied current (0.02–0.32 mA\\/cm2), TiO2 loading

Zacharias Frontistis; Vasileia M. Daskalaki; Alexandros Katsaounis; Ioannis Poulios; Dionissios Mantzavinos

2011-01-01

179

Cu(2)ZnSnS(4)-Pt and Cu(2)ZnSnS(4)-Au heterostructured nanoparticles for photocatalytic water splitting and pollutant degradation.  

PubMed

Cu2ZnSnS4, based on abundant and environmental friendly elements and with a direct band gap of 1.5 eV, is a main candidate material for solar energy conversion through both photovoltaics and photocatalysis. We detail here the synthesis of quasi-spherical Cu2ZnSnS4 nanoparticles with unprecedented narrow size distributions. We further detail their use as seeds to produce CZTS-Au and CZTS-Pt heterostructured nanoparticles. Such heterostructured nanoparticles are shown to have excellent photocatalytic properties toward degradation of Rhodamine B and hydrogen generation by water splitting. PMID:24946131

Yu, Xuelian; Shavel, Alexey; An, Xiaoqiang; Luo, Zhishan; Ibáñez, Maria; Cabot, Andreu

2014-07-01

180

Synthesis and visible light photocatalysis of Fe-doped TiO 2 mesoporous layers deposited on hollow glass microbeads  

NASA Astrophysics Data System (ADS)

Nano-composite of Fe-doped anatase TiO 2 nanocrystals loaded on the hollow glass microbeads was prepared by co-thermal hydrolysis deposition and calcining treatment. The adherence of TiO 2 mesoporous layers to the surfaces of hollow glass microbeads prevented the aggregation of TiO 2 nanoparticles and benefited to their catalytic activity. The doping of Fe ions makes the absorption edge of the TiO 2 based nano-composite red-shifted into the visible region. An effective photodegradation of the methyl orange aqueous solution was achieved under visible light ( ?>420 nm) irradiation, revealing the potential applicability of such nano-composite in some industry fields, such as air and water purifications.

Cui, Lifeng; Wang, Yuansheng; Niu, Mutong; Chen, Guoxin; Cheng, Yao

2009-10-01

181

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

PubMed

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

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

2014-07-01

182

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

2012-04-15

183

Pulsed laser deposition of cluster-assembled films for catalysis and the photocatalysis relevant to energy and the environment  

NASA Astrophysics Data System (ADS)

Nanoparticles (NPs) catalysts are under intense investigation in the catalysis community due to their exceptional activity and selective nature in catalytic processes as compared to the corresponding bulk counterpart, especially because of their large surface-to-volume atomic ratio, size- and shape-dependent properties, and high concentration of low-coordinated active surface sites. However, there is no general strategy to synthesize NPs of various materials with narrow size distribution, tailored properties, and desired morphologies. The development of a technique able to prepare NPs is thus a goal of great importance to avoid present trial and error approaches. Here we report on selected examples where pulsed laser deposition (PLD) technique greatly contributes toward NPs synthesis. Co NPs embedded in B matrix films have been synthesized by PLD technique by taking advantage of the phase explosion process of superheated liquid where a mixture of vapor and liquid droplets leave the irradiated target surface and get deposited on the substrate. The deposited NPs exhibit catalytic properties comparable to that of precious metals in hydrogen production by hydrolysis of NaBH4 and NH3BH3. These NPs, when supported on rough carbon film prepared by PLD, show about 30% increase in catalytic activity for H2 production as compared to unsupported NPs. Co3O4 NPs assembled coating has been produced by reactive PLD in oxygen atmosphere at various substrate temperatures from room temperature to 250 °C. It was proved that the Co3O4 NPs can be obtained in a single step at low temperatures with mixed disordered-nanocrystalline phase that is a relevant feature for catalysis. The Co3O4 NPs assembled thin coating, employed in degradation of methylene blue solution, in water, via photo Fenton reaction in presence of H2O2, exhibits significantly higher activity as compared to the corresponding homogeneous catalyst.

Miotello, A.; Patel, N.

2013-08-01

184

Selective isolation of the electron or hole in photocatalysis: ZnO-TiO2 and TiO2-ZnO core-shell structured heterojunction nanofibers via electrospinning and atomic layer deposition  

NASA Astrophysics Data System (ADS)

Heterojunctions are a well-studied material combination in photocatalysis studies, the majority of which aim to improve the efficacy of the catalysts. Developing novel catalysts begs the question of which photo-generated charge carrier is more efficient in the process of catalysis and the associated mechanism. To address this issue we have fabricated core-shell heterojunction (CSHJ) nanofibers from ZnO and TiO2 in two combinations where only the `shell' part of the heterojunction is exposed to the environment to participate in the photocatalysis. Core and shell structures were fabricated via electrospinning and atomic layer deposition, respectively which were then subjected to calcination. These CSHJs were characterized and studied for photocatalytic activity (PCA). These two combinations expose electrons or holes selectively to the environment. Under suitable illumination of the ZnO-TiO2 CSHJ, e/h pairs are created mainly in TiO2 and the electrons take part in catalysis (i.e. reduce the organic dye) at the conduction band or oxygen vacancy sites of the `shell', while holes migrate to the core of the structure. Conversely, holes take part in catalysis and electrons diffuse to the core in the case of a TiO2-ZnO CSHJ. The results further revealed that the TiO2-ZnO CSHJ shows ~1.6 times faster PCA when compared to the ZnO-TiO2 CSHJ because of efficient hole capture by oxygen vacancies, and the lower mobility of holes.Heterojunctions are a well-studied material combination in photocatalysis studies, the majority of which aim to improve the efficacy of the catalysts. Developing novel catalysts begs the question of which photo-generated charge carrier is more efficient in the process of catalysis and the associated mechanism. To address this issue we have fabricated core-shell heterojunction (CSHJ) nanofibers from ZnO and TiO2 in two combinations where only the `shell' part of the heterojunction is exposed to the environment to participate in the photocatalysis. Core and shell structures were fabricated via electrospinning and atomic layer deposition, respectively which were then subjected to calcination. These CSHJs were characterized and studied for photocatalytic activity (PCA). These two combinations expose electrons or holes selectively to the environment. Under suitable illumination of the ZnO-TiO2 CSHJ, e/h pairs are created mainly in TiO2 and the electrons take part in catalysis (i.e. reduce the organic dye) at the conduction band or oxygen vacancy sites of the `shell', while holes migrate to the core of the structure. Conversely, holes take part in catalysis and electrons diffuse to the core in the case of a TiO2-ZnO CSHJ. The results further revealed that the TiO2-ZnO CSHJ shows ~1.6 times faster PCA when compared to the ZnO-TiO2 CSHJ because of efficient hole capture by oxygen vacancies, and the lower mobility of holes. Electronic supplementary information (ESI) available: Additional SEM image of the CSHJ, XPS spectra and mechanism demonstrating PCA at the surface of pure TiO2. See DOI: 10.1039/c3nr06665g

Kayaci, Fatma; Vempati, Sesha; Ozgit-Akgun, Cagla; Donmez, Inci; Biyikli, Necmi; Uyar, Tamer

2014-05-01

185

Overview of Photocatalysis, Photocatalytic Surface Materials Studies, and Demonstration of Self-Cleaning Materials for Space and Terrestrial Based Applications at the Infinity Science Center at NASA Stennis Space Center  

NASA Technical Reports Server (NTRS)

Research into photocatalytic technology has been progressing for over three decades in the early 1990s Japanese and European companies initiate research into photocatalytic technology. In the 1996 specific focus on the technology with the first large-scale application: the construction of a church in Rome (Jubilee Church). And in 2000 Europe and Japan research into the benefits of photocatalytic technology. Currently, photocatalytic technology continues to improve, and with time development is becoming more efficient and effective. What is Photocatalysis? Photo: phenomenon induced by the light, having specifically a wavelength around 320-400 nm (artificial or natural sunlight). Catalyst: a material that induces a reaction but is not consumed or transformed by it. The catalyst remains constantly available. In this case, the catalyst is made with nano-particles of titanium oxide (Ti02).

Underwood, Lauren W.

2012-01-01

186

Photocatalytic antifouling graphene oxide-mediated hierarchical filtration membranes with potential applications on water purification.  

PubMed

Graphene oxide-based filtration membranes with photocatalytic antifouling function have been successfully synthesized by a two-step method for the first time. First, graphene oxide particles composite sheets are prepared by decorating graphene oxide sheets with appropriate amount of TiO2 nanoparticles, which can be assembled into filtration membranes with suitable permeation and retention rates. Then, an additional TiO2 particle layer (P25) with strong photocatalysis activity is coated on these films by filtration, forming hierarchical structure membranes. The filtration properties of the as-obtained films are investigated by treating dye solution, and the results demonstrate that these membranes possess favorable photocatalytic antifouling function under UV light irradiation, which can maintain the clean films and their filtration properties, broadening the horizon for the vast use of these graphene-involved films in water purification. PMID:25148296

Xu, Chao; Xu, Yuelian; Zhu, Jiaoli

2014-09-24

187

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

PubMed

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

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

2014-10-01

188

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

189

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

PubMed

Solar overall water splitting is a promising sustainable approach for solar-to-chemical energy conversion, which harnesses solar irradiation to oxidize water to oxygen and reduce the protons to hydrogen. The water oxidation step is vital but difficult to achieve through inorganic photocatalysis. However, nature offers an efficient light-driven water-oxidizing enzyme, photosystem II (PSII). Here we report an overall water splitting natural-artificial hybrid system, in which the plant PSII and inorganic photocatalysts (for example, Ru/SrTiO3:Rh), coupled with an inorganic electron shuttle [Fe(CN)6(3-)/Fe(CN)6(4-)], are integrated and dispersed in aqueous solutions. The activity of this hybrid photosystem reaches to around 2,489 mol H2 (mol PSII)(-1) h(-1) under visible light irradiation, and solar overall water splitting is also achieved under solar irradiation outdoors. The optical imaging shows that the hybrid photosystems are constructed through the self-assembly of PSII adhered onto the inorganic photocatalyst surface. Our work may provide a prototype of natural-artificial hybrids for developing autonomous solar water splitting system. PMID:25115942

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

2014-01-01

190

Water Resources Water Quality and Water Treatment  

E-print Network

Water Resources TD 603 Lecture 1: Water Quality and Water Treatment CTARA Indian Institute of Technology, Bombay 2nd November, 2011 #12;OVERVIEW Water Quality WATER TREATMENT PLANTS WATER TREATMENT PLANTS WATER TREATMENT PLANTS WATER TRE OVERVIEW OF THE LECTURE 1. Water Distribution Schemes Hand Pump

Sohoni, Milind

191

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

PubMed

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

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

2014-05-01

192

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

PubMed

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

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

2014-06-28

193

Turbid water Clear water  

E-print Network

Turbid water Clear water pixel position cameraresponsecameraresponse pixel position ABSTRACT: A new the backscatter component resulting in enhanced performance in turbid waters. The system is expected to provide-submerged mines in turbid coastal waters. To extract high resolution bathymetric information optically from turbid

Jaffe, Jules

194

Water oxidation by electrodeposited cobalt oxides--role of anions and redox-inert cations in structure and function of the amorphous catalyst.  

PubMed

For the production of nonfossil fuels, water oxidation by inexpensive cobalt-based catalysts is of high interest. Films for the electrocatalysis of water oxidation were obtained by oxidative self-assembly (electrodeposition) from aqueous solutions containing, apart from Co, either K, Li or Ca with either a phosphate, acetate or chloride anion. X-ray absorption spectroscopy (XAS) at the Co K-edge revealed clusters of edge-sharing CoO(6) octahedra in all films, but the size or structural disorder of the Co-oxido clusters differed. Whereas potassium binding is largely unspecific, CaCo(3) O(4) cubanes, which resemble the CaMn(3) O(4) cubane of the biological catalyst in oxygenic photosynthesis, may form, as suggested by XAS at the Ca K-edge. Cyclic voltammograms in a potassium phosphate buffer at pH?7 revealed that no specific combination of anions and redox-inactive cations is required for catalytic water oxidation. However, the anion type modulates not only the size (or order) of the Co-oxido clusters, but also electrodeposition rates, redox potentials, the capacity for oxidative charging, and catalytic currents. On these grounds, structure-activity relations are discussed. PMID:22323319

Risch, Marcel; Klingan, Katharina; Ringleb, Franziska; Chernev, Petko; Zaharieva, Ivelina; Fischer, Anna; Dau, Holger

2012-03-12

195

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.

196

Water, Water Everywhere! Research the Water Cycle  

NSDL National Science Digital Library

Water, Water Everywhere! Research the Water Cycle asks students to conduct their own research on the water cycle (hydrologic cycle). Working collaboratively in small groups, students will research and write about the relationships between stages in the water cycle and the three states of matter relating to water. After completing this lesson, students will be prepared to create a model of the water cycle.

Bale, Regina

2012-07-17

197

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

EPA Science Inventory

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

198

Water, water everywhere  

Microsoft Academic Search

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

Pennisi

1993-01-01

199

Cost-effective and eco-friendly synthesis of novel and stable N-doped ZnO/g-C3N4 core-shell nanoplates with excellent visible-light responsive photocatalysis  

NASA Astrophysics Data System (ADS)

N-doped ZnO/g-C3N4 hybrid core-shell nanoplates have been successfully prepared via a facile, cost-effective and eco-friendly ultrasonic dispersion method for the first time. HRTEM studies confirm the formation of the N-doped ZnO/g-C3N4 hybrid core-shell nanoplates with an average diameter of 50 nm and the g-C3N4 shell thickness can be tuned by varying the content of loaded g-C3N4. The direct contact of the N-doped ZnO surface and g-C3N4 shell without any adhesive interlayer introduced a new carbon energy level in the N-doped ZnO band gap and thereby effectively lowered the band gap energy. Consequently, the as-prepared hybrid core-shell nanoplates showed a greatly enhanced visible-light photocatalysis for the degradation of Rhodamine B compare to that of pure N-doped ZnO surface and g-C3N4. Based on the experimental results, a proposed mechanism for the N-doped ZnO/g-C3N4 photocatalyst was discussed. Interestingly, the hybrid core-shell nanoplates possess high photostability. The improved photocatalytic performance is due to a synergistic effect at the interface of the N-doped ZnO and g-C3N4 including large surface-exposure area, energy band structure and enhanced charge-separation properties. Significantly, the enhanced performance also demonstrates the importance of evaluating new core-shell composite photocatalysts with g-C3N4 as shell material.N-doped ZnO/g-C3N4 hybrid core-shell nanoplates have been successfully prepared via a facile, cost-effective and eco-friendly ultrasonic dispersion method for the first time. HRTEM studies confirm the formation of the N-doped ZnO/g-C3N4 hybrid core-shell nanoplates with an average diameter of 50 nm and the g-C3N4 shell thickness can be tuned by varying the content of loaded g-C3N4. The direct contact of the N-doped ZnO surface and g-C3N4 shell without any adhesive interlayer introduced a new carbon energy level in the N-doped ZnO band gap and thereby effectively lowered the band gap energy. Consequently, the as-prepared hybrid core-shell nanoplates showed a greatly enhanced visible-light photocatalysis for the degradation of Rhodamine B compare to that of pure N-doped ZnO surface and g-C3N4. Based on the experimental results, a proposed mechanism for the N-doped ZnO/g-C3N4 photocatalyst was discussed. Interestingly, the hybrid core-shell nanoplates possess high photostability. The improved photocatalytic performance is due to a synergistic effect at the interface of the N-doped ZnO and g-C3N4 including large surface-exposure area, energy band structure and enhanced charge-separation properties. Significantly, the enhanced performance also demonstrates the importance of evaluating new core-shell composite photocatalysts with g-C3N4 as shell material. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr05271k

Kumar, Santosh; Baruah, Arabinda; Tonda, Surendar; Kumar, Bharat; Shanker, Vishnu; Sreedhar, B.

2014-04-01

200

Noble metals can have different effects on photocatalysis over metal-organic frameworks (MOFs): a case study on M/NH?-MIL-125(Ti) (M=Pt and Au).  

PubMed

M-doped NH2-MIL-125(Ti) (M=Pt and Au) were prepared by using the wetness impregnation method followed by a treatment with H2 flow. The resultant samples were characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption fine structure (XAFS) analyses, N2-sorption BET surface area, and UV/Vis diffuse reflectance spectroscopy (DRS). The photocatalytic reaction carried out in saturated CO2 with triethanolamine (TEOA) as sacrificial agent under visible-light irradiations showed that the noble metal-doping on NH2-MIL-125(Ti) promoted the photocatalytic hydrogen evolution. Unlike that over pure NH2-MIL-125(Ti), in which only formate was produced, both hydrogen and formate were formed over Pt- and Au-loaded NH2-MIL-125(Ti). However, Pt and Au have different effects on the photocatalytic performance for formate production. Compared with pure NH2-MIL-125(Ti), Pt/NH2-MIL-125(Ti) showed an enhanced activity for photocatalytic formate formation, whereas Au has a negative effect on this reaction. To elucidate the origin of the different photocatalytic performance, electron spin resonance (ESR) analyses and density functional theory (DFT) calculations were carried out over M/NH2-MIL-125(Ti).The photocatalytic mechanisms over M/NH2-MIL-125(Ti) (M=Pt and Au) were proposed. For the first time, the hydrogen spillover from the noble metal Pt to the framework of NH2-MIL-125(Ti) and its promoting effect on the photocatalytic CO2 reduction is revealed. The elucidation of the mechanism on the photocatalysis over M/NH2-MIL-125(Ti) can provide some guidance in the development of new photocatalysts based on MOF materials. This study also demonstrates the potential of using noble metal-doped MOFs in photocatalytic reactions involving hydrogen as a reactant, like hydrogenation reactions. PMID:24644131

Sun, Dengrong; Liu, Wenjun; Fu, Yanghe; Fang, Zhenxing; Sun, Fangxiang; Fu, Xianzhi; Zhang, Yongfan; Li, Zhaohui

2014-04-14

201

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

NASA Astrophysics Data System (ADS)

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

Doudrick, Kyle

202

Some observations on the development of superior photocatalytic systems for application to water purification by the "adsorb and shuttle" or the interphase charge transfer mechanisms.  

PubMed

Adsorb and shuttle (A/S) and interfacial charge transfer are the two major strategies for overcoming recombination in photocatalysis in this era of nanoparticle composites. Their relationships are considered here. A review of key literature is accompanied by a presentation of three new experiments within the overall aim of assessing the relation of these strategies. The cases presented include: A/S by a high silica zeolite/TiO2 composite, charge transfer (CT) between phases in a TiO2/WO3 composite and both A/S and CT by composites of TiO2 with powered activated carbon (AC) and single-walled carbon nanotubes (SWCNT). The opportunities presented by the two strategies for moving toward photocatalysts that could support applications for the removal of contaminants from drinking water or that lead to a practical adsorbent for organics that could be regenerated photocatalytically link this discussion to ongoing research here. PMID:25432008

Langford, Cooper; Izadifard, Maryam; Radwan, Emad; Achari, Gopal

2014-01-01

203

UNL WATER CENTER WATER CURRENT  

E-print Network

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

Nebraska-Lincoln, University of

204

UNL WATER CENTER WATER CURRENT  

E-print Network

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

Nebraska-Lincoln, University of

205

UNL WATER CENTER WATER CURRENT  

E-print Network

INSIDE UNL WATER CENTER WATER CURRENT PROTECTING NEBRASKA'S WATER RESOURCES THROUGH RESEARCH ........SPECIAL BUREAU OF RECLAMATION CENTENNIAL COVERAGE 14..............Water News Briefs 15..............Calendar 16..............Bottled Water or Tap? (continued on page 13) Fall NSIA/NWRA Convention Focuses

Nebraska-Lincoln, University of

206

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

207

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

208

One-step synthesis of metal@titania core-shell materials for visible-light photocatalysis and catalytic reduction reaction.  

PubMed

Metal@TiO2 composites with a core-shell structure possess multifunctional properties. The demonstrated protocols for synthesizing such materials involve multiple steps, requiring precise control over the particle uniformity of the core and shell thickness, as well as complex surface modification. A simple approach to synthesizing metal@TiO2 hybrid nanostructures remains a great challenge. Herein, we report on a one-step method for the preparation of metal@TiO2 core-shell nanospheres, which exhibited excellent performance in photocatalytic degradation of recalcitrant organic pollutants under visible light irradiation, and in catalytic reduction of nitrophenol in water. The simple method described here represents a sustainable approach to preparing core-shell materials at low cost, involving fewer chemicals, and requiring less energy, which will make a significant contribution toward large-scale synthesis of high-performance hybrid materials for photocatalytic applications. PMID:25236773

Xiong, Zhigang; Zhang, Luhong; Zhao, Xiu Song

2014-11-01

209

Effect of water composition on the photocatalytic removal of pesticides with different TiO2 catalysts.  

PubMed

The objective of this work is double-firstly to explore the photocatalytic efficiency of five different commercial TiO2 catalysts in the photodegradation of a mixture of pesticides classified by the EU as priority pollutants and secondly to analyze the correlation between their physicochemical properties and the inhibition of the studied photocatalytic process when natural water was employed. Photocatalytic efficiencies when ultrapure water was used seem to point out that surface area was not a prerequisite for the photodegradation of the selected mixture of pesticides. On the other hand, significant differences in total organic carbon (TOC) conversions were obtained with the two studied water compositions. On one side, Evonik materials appear to be mostly inhibited when natural water was employed, whereas on the other, it should be remarked that anatase Sigma-Aldrich (SA) and, particularly, Hombikat UV100 (HBK) materials presented a very limited photo-efficiency inhibition or even a higher initial rate of TOC removal when a natural water matrix was used, probably due to their specific surface properties (PZC, S BET). Therefore, heterogeneous photocatalysis has proved to be a promising technology for the degradation of the selected mixture of pesticides where the final photo-efficiency of the five commercial titania catalysts studied here responds to a complex balance between its surface and structural properties. PMID:24910310

Carbajo, Jaime; García-Muñoz, Patricia; Tolosana-Moranchel, Alvaro; Faraldos, Marisol; Bahamonde, Ana

2014-11-01

210

Water, water everywhere  

SciTech Connect

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

Pennisi, E.

1993-02-20

211

Visible light photocatalytic water disinfection and its kinetics using Ag-doped titania nanoparticles.  

PubMed

The UN estimated about five million deaths every year due to water-borne diseases, accounting from four billion patients. Keeping in view, the ever increasing health issues and to undermine this statistics, a reliable and sustainable water-treatment method has been developed using visible light for water treatment. titania nanoparticles (NPs) have been synthesized successfully by a more applicable method Viz: liquid impregnation (LI) method. The bacterial death rate by photocatalysis under visible light was studied by employing a typical fluorescent source and was found to follow pseudo first-order reaction kinetics. The nanoparticles were characterized using X-ray diffraction (XRD), scanning electron microscopy, and energy-dispersive X-ray spectroscopy to deduce their size range, surface morphology, and elemental compositions, respectively. Among all the prepared grades, 1% Ag-TiO2 was found to be a very effective photocatalytic agent against Escherichia coli. The resulted photoinactivated data were also evaluated by different empirical kinetic models for bacterial inactivation. Hom, Hom-power, Rational, and Selleck models were not able to explain the disinfection kinetics but modified-Hom model fitted best with the experimentally obtained data by producing a shoulder, log-linear, and a tail region. PMID:23872896

Younas, Hassan; Qazi, Ishtiaq A; Hashmi, Imran; Awan, M Ali; Mahmood, Asif; Qayyum, Hafiz Adil

2014-01-01

212

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

SciTech Connect

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

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

2013-02-15

213

Graphene-analogue carbon nitride: novel exfoliation synthesis and its application in photocatalysis and photoelectrochemical selective detection of trace amount of Cu2+  

NASA Astrophysics Data System (ADS)

Graphene-analogue nanostructures defined as a new kind of promising materials with unique electronic, surface and optical properties have received much attention in the fields of catalysis, energy storage, sensing and electronic devices. Due to the distinctive structure characteristics of the graphene-analogue materials, they brought novel and amazing properties. Herein, graphene-analogue carbon nitride (GA-C3N4) was synthesized by high-yield, large-scale thermal exfoliation from the graphitic C3N4-based intercalation compound. Graphene-analogue carbon nitride exhibited 2D thin-layer structure with 6-9 atomic thickness, a high specific surface area of 30.1 m2 g-1, increased photocurrent responses and improved electron transport ability, which could give rise to enhancing the photocatalytic activity and stability. The graphene-analogue carbon nitride had a new features that could make it suitable as a sensor for Cu2+ determination. So GA-C3N4 is a new but promising candidate for heavy metal ions (Cu2+) determination in water environment. The photocatalytic mechanism and photoelectrochemical selective sensing of Cu2+ were also discussed.Graphene-analogue nanostructures defined as a new kind of promising materials with unique electronic, surface and optical properties have received much attention in the fields of catalysis, energy storage, sensing and electronic devices. Due to the distinctive structure characteristics of the graphene-analogue materials, they brought novel and amazing properties. Herein, graphene-analogue carbon nitride (GA-C3N4) was synthesized by high-yield, large-scale thermal exfoliation from the graphitic C3N4-based intercalation compound. Graphene-analogue carbon nitride exhibited 2D thin-layer structure with 6-9 atomic thickness, a high specific surface area of 30.1 m2 g-1, increased photocurrent responses and improved electron transport ability, which could give rise to enhancing the photocatalytic activity and stability. The graphene-analogue carbon nitride had a new features that could make it suitable as a sensor for Cu2+ determination. So GA-C3N4 is a new but promising candidate for heavy metal ions (Cu2+) determination in water environment. The photocatalytic mechanism and photoelectrochemical selective sensing of Cu2+ were also discussed. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr04759h

Xu, Hui; Yan, Jia; She, Xiaojie; Xu, Li; Xia, Jiexiang; Xu, Yuanguo; Song, Yanhua; Huang, Liying; Li, Huaming

2014-01-01

214

Water, Water Everywhere!  

ERIC Educational Resources Information Center

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

Sible, Kathleen P.

2000-01-01

215

Water Works.  

ERIC Educational Resources Information Center

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

Van De Walle, Carol

1988-01-01

216

One-pot solvothermal synthesis of ZnSe·xN2H4/GS and ZnSe/N-GS and enhanced visible-light photocatalysis.  

PubMed

Doped-graphene has attracted considerable attention in many fields because doping element can alter the electrical properties of graphene. In this paper, we synthesized ZnSe·xN2H4/graphene (ZnSe·xN2H4/GS) and ZnSe/nitrogen-doped graphene (ZnSe/N-GS) nanocomposites with p-n junctions via one-pot solvothermal process. The structure, morphologies and catalytic performance of the ZnSe·xN2H4/GS and ZnSe/N-GS are characterized by X-ray diffraction pattern (XRD), field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy (RS), X-ray photoelectron spectroscopy (XPS), and cathodoluminescence spectrum (CL), respectively. Our experiments show that the as-prepared nanocomposites ZnSe·xN2H4/GS and ZnSe/N-GS exhibit remarkably enhanced photocatalytic activities for methylene blue (MB) dye under visible light irradiation. Even importantly, ZnSe/N-GS would make this degradation process more effective. Overall, this facile and catalyst-free synthesize method in this work could provide new insights into the fabrication of other composites based on doped graphene with high performance photocatalysts, which show their potential applications in producing of hydrogen through water splitting, environmental protection issues. PMID:23945131

Liu, Bitao; Tian, Liangliang; Wang, Yuhua

2013-09-11

217

Ground Water  

NSDL National Science Digital Library

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

2008-05-28

218

water intake Water sampling site  

E-print Network

x Drinking water intake WWTP discharge WWTP Water sampling site Reference MICROPOLLUTANT PLUME at WWTP discharge · Conductivity may be used to predict concentrations of waste water derived MPs downstream, a drinking water plant pumps lake water (ca. 100'000 m3 /day) for potable water (sand filter

219

UNL WATER CENTER WATER CURRENT  

E-print Network

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

Nebraska-Lincoln, University of

220

UNL WATER CENTER WATER CURRENT  

E-print Network

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

Nebraska-Lincoln, University of

221

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 ...

222

Photocatalytic water splitting for hydrogen generation on cubic, orthorhombic, and tetragonal KNbO3 microcubes  

NASA Astrophysics Data System (ADS)

Potassium niobate (KNbO3) microcubes with orthorhombic and tetragonal phases were hydrothermally prepared and characterized by powder X-ray diffraction, nitrogen adsorption-desorption, micro-Raman spectroscopy, Fourier transform infrared spectroscopy, diffuse reflectance UV-visible spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy. The photoreactivity of the as-prepared KNbO3 samples was evaluated regarding the hydrogen evolution from aqueous methanol under UV, and the results were compared with that of cubic KNbO3 microcubes. The photocatalytic reactivity was shown to be phase-dependent, following the order cubic > orthorhombic > tetragonal. Insight into the phase-dependent photocatalytic properties was gained by first-principles density functional calculations. The best photocatalytic performance of cubic KNbO3 is ascribed to it having the highest symmetry in the bulk structure and associated unique electronic structure. Further, the surface electronic structure plays a key role leading to the discrepancy in photoreactivity between orthorhombic and tetragonal KNbO3. The results from this study are potentially applicable to a range of perovskite-type mixed metal oxides useful in water splitting as well as other areas of heterogeneous photocatalysis.Potassium niobate (KNbO3) microcubes with orthorhombic and tetragonal phases were hydrothermally prepared and characterized by powder X-ray diffraction, nitrogen adsorption-desorption, micro-Raman spectroscopy, Fourier transform infrared spectroscopy, diffuse reflectance UV-visible spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy. The photoreactivity of the as-prepared KNbO3 samples was evaluated regarding the hydrogen evolution from aqueous methanol under UV, and the results were compared with that of cubic KNbO3 microcubes. The photocatalytic reactivity was shown to be phase-dependent, following the order cubic > orthorhombic > tetragonal. Insight into the phase-dependent photocatalytic properties was gained by first-principles density functional calculations. The best photocatalytic performance of cubic KNbO3 is ascribed to it having the highest symmetry in the bulk structure and associated unique electronic structure. Further, the surface electronic structure plays a key role leading to the discrepancy in photoreactivity between orthorhombic and tetragonal KNbO3. The results from this study are potentially applicable to a range of perovskite-type mixed metal oxides useful in water splitting as well as other areas of heterogeneous photocatalysis. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr02356g

Zhang, Tingting; Zhao, Kun; Yu, Jiaguo; Jin, Jian; Qi, Yang; Li, Huiquan; Hou, Xinjuan; Liu, Gang

2013-08-01

223

Water, Water Everywhere, But...  

ERIC Educational Resources Information Center

Materials for teaching a unit on water pollution are provided in this teaching package. These materials include: (1) a student reading booklet; (2) a reference booklet listing a variety of popular chemical, biological, and physical tests which can be performed on a local waterway and providing information about the environmental effects and toxic…

Jacobson, Cliff

224

Photocatalytic degradation of hexazinone and its determination in water via UPLC-MS/MS.  

PubMed

Degradation of hexazinone has been investigated by means of photocatalysis of mixed-phase crystal nano-TiO(2). Influences of adsorption, amount of nano-TiO(2), pH and irradiation time on the photocatalytic process are studied. Results show that hexazinone is totally degraded within 40min of irradiation under pH neutral conditions. This compares favorably with Degussa P25 TiO(2) when conducted under the same experimental conditions. Preliminary photocatalytic kinetic information for hexazinone degradation is proposed. First order kinetics is obtained for the adsorption and photocatalytic degradation reactions, which fit the Langmuir-Hinshelwood model. A rapid, sensitive and accurate UPLC-MS/MS technique is developed and utilized to determine the level of hexazinone in water in support of the degradation kinetics study. The results indicate a limit of detection (LOD) at 0.05?g/l and the recoveries between 90.2 and 98.5% with relative standard deviations (RSD) lower than 12%. A LC-MS/MS technique is used to trace the degradation process. Complete degradation is achieved into final products including nontoxic water, carbon dioxide and urea. A probable pathway for the total photocatalytic degradation of hexazinone is proposed. PMID:22551636

Mei, Mei; Du, Zhenxia; Xu, Ruifen; Chen, Yun; Zhang, Haojie; Qu, Shuping

2012-06-30

225

Drinking Water  

NSDL National Science Digital Library

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

226

Low Overpotential in Vacancy-Rich Ultrathin CoSe2 Nanosheets for Water Oxidation.  

PubMed

According to Yang Shao-Horn's principle, CoSe2 is a promising candidate as an efficient, affordable, and sustainable alternative electrocatalyst for the oxygen evolution reaction, owing to its well-suited electronic configuration of Co ions. However, the catalytic efficiency of pure CoSe2 is still far below what is expected, because of its poor active site exposure yield. Herein, we successfully overcome the disadvantage of insufficient active sites in bulk CoSe2 by reducing its thickness into the atomic scale rather than any additional modification (such as doping or hybridizing with graphene or noble metals). The positron annihilation spectrometry and XAFS spectra provide clear evidence that a large number of VCo? vacancies formed in the ultrathin nanosheets. The first-principles calculations reveal that these VCo? vacancies can serve as active sites to efficiently catalyze the oxygen evolution reaction, manifesting an OER overpotential as low as 0.32 V at 10 mA cm(-2) in pH 13 medium, which is superior to the values for its bulk counterparts as well as those for the most reported Co-based electrocatalysts. Considering the outstanding performance of the simple, unmodified ultrathin CoSe2 nanosheets as the only catalyst, further improvement of the catalytic activity is expected when various strategies of doping or hybridizing are used. These results not only demonstrate the potential of a notable, affordable, and earth-abundant water oxidation electrocatalyst based on ultrathin CoSe2 nanosheets but also open up a promising avenue into the exploration of excellent active and durable catalysts toward replacing noble metals for oxygen electrocatalysis. PMID:25310506

Liu, Youwen; Cheng, Hao; Lyu, Mengjie; Fan, Shaojuan; Liu, Qinghua; Zhang, Wenshuai; Zhi, Yuduo; Wang, Chengming; Xiao, Chong; Wei, Shiqiang; Ye, Bangjiao; Xie, Yi

2014-11-01

227

Healthy Water  

MedlinePLUS

... Z With its many uses for drinking, recreation, sanitation, hygiene, and industry, water is our most precious ... Systems, Water Fluoridation, Camping, Hiking, Travel… Global Water, Sanitation, & Hygiene (WASH) Community Systems, Household Treatment & Storage, Sanitation ...

228

Parasites: Water  

MedlinePLUS

... be at greater risk for serious illness. Proper sanitation and hygiene are also essential to preventing waterborne ... CDC’s Healthy Water website CDC Global WASH (Water, Sanitation and Hygiene) Programs and Projects page Drinking Water: ...

229

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 ...

230

Search for the ANSER (A "Life at the Frontiers of Energy Research" contest entry from the 2011 Energy Frontier Research Centers (EFRCs) Summit and Forum  

ScienceCinema

'Search for the ANSER' was submitted by the Argonne-Northwestern Solar Energy Research Center (ANSER) to the 'Life at the Frontiers of Energy Research' video contest at the 2011 Science for Our Nation's Energy Future: Energy Frontier Research Centers (EFRCs) Summit and Forum. Twenty-six EFRCs created short videos to highlight their mission and their work. ANSER, an EFRC directed by Michael Wasielewski at Argonne National Laboratory is a partnership of scientists from five institutions: Argonne National Laboratory, Northwestern University, University of Chicago, University of Illinois at Urbana-Champaign, and Yale. The Office of Basic Energy Sciences in the U.S. Department of Energy's Office of Science established the 46 Energy Frontier Research Centers (EFRCs) in 2009. These collaboratively-organized centers conduct fundamental research focused on 'grand challenges' and use-inspired 'basic research needs' recently identified in major strategic planning efforts by the scientific community. The overall purpose is to accelerate scientific progress toward meeting the nation's critical energy challenges. At ANSER, the mission is 'to revolutionize our understanding of molecules, materials and methods necessary to create dramatically more efficient technologies for solar fuels and electricity production.' Research topics are: catalysis (water), electrocatalysis, photocatalysis, photoelectrocatalysis, solar photovoltaic, solar fuels, solar electrodes, photosynthesis, transportation fuels, bio-inspired, spin dynamics, hydrogen (fuel), ultrafast physics, interfacial characterization, matter by design, novel materials synthesis, charge transport, and self-assembly.

Wasielewski, Michael R. (Director, Argonne-Northwestern Solar Energy Research Center); ANSER Staff

2011-11-02

231

Water Treatment  

NSDL National Science Digital Library

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

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

2006-01-01

232

UNL WATER CENTER WATER CURRENT  

E-print Network

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

Nebraska-Lincoln, University of

233

UNL WATER CENTER WATER CURRENT  

E-print Network

to water, such as from fertil- izer, animal waste or natu- rally occurring soils. In a couple opera-tion (CAFO) waste lagoon as part of a two-year UNL Water Sciences Laboratory study to determineINSIDE UNL WATER CENTER WATER CURRENT PROTECTING NEBRASKA'S WATER RESOURCES THROUGH RESEARCH

Nebraska-Lincoln, University of

234

UNL WATER CENTER WATER CURRENT  

E-print Network

where the run- off water first leaves the edge of the field. Current drought conditions have somewhatINSIDE UNL WATER CENTER WATER CURRENT PROTECTING NEBRASKA'S WATER RESOURCES THROUGH RESEARCH Researchers Honing Methods to Sample Field Run-off Water by Steve Ress The effectiveness of riparian buffer

Nebraska-Lincoln, University of

235

Water, Water Everywhere  

NSDL National Science Digital Library

Students learn about floods, discovering that different types of floods occur from different water sources, but primarily from heavy rainfall. While floods occur naturally and have benefits such as creating fertile farmland, students learn that with the increase in human population in flood-prone areas, floods are become increasingly problematic. Both natural and manmade factors contribute to floods. Students learn what makes floods dangerous and what engineers design to predict, control and survive floods.

Integrated Teaching And Learning Program

236

Remediation of Water Contaminated with an Azo Dye: An Undergraduate Laboratory Experiment Utilizing an Inexpensive Photocatalytic Reactor  

NASA Astrophysics Data System (ADS)

The construction and use of an inexpensive photocatalytic reactor that utilizes titanium dioxide as the photocatalyst for wastewater treatment is described. In these experiments and in supplementary material, students are made aware that a variety of techniques have been developed to treat wastewaters, including those generated by the chemical industry. Water contaminated with the azo dye Congo Red was selected as an example of how one might treat contaminated water from a textile manufacturing facility. These experiments emphasize that, in addition to product development, chemists must also be concerned with waste treatment. A summary of the theory of titanium dioxide-mediated photocatalysis is provided. The phenomenon of photosensitization is also discussed. The usefulness of Congo Red is summarized and a brief history of this dye is given. In addition to being inexpensive, the photocatalytic reactor described is easy to construct and uses a readily available low-wattage fluorescent light. An important feature of this reactor is that the heat generated by the light source is readily dissipated by the water undergoing treatment. Thus no special cooling apparatus is required. One of the most important aspects of this work is that it provides a wide variety of continuing research suggestions that would be suitable and readily accomplished in undergraduate departments and high school laboratories; even those where budgetary priorities are a major concern. Use of this reactor would also enable students to design systems to treat "real-world" wastes, including some that are generated in instructional laboratories.

Bumpus, John A.; Tricker, Jennifer; Andrzejewski, Ken; Rhoads, Heather; Tatarko, Matthew

1999-12-01

237

The Water Cycle: Water Storage  

NSDL National Science Digital Library

This interactive, animated graphic helps explain the water cycle to younger students. The animation, with sound, explains the various parts of the water cycle and show how water moves from one part to another.

238

WATER USAGE  

NSDL National Science Digital Library

DESK Standard: Understand how the water cycle relates to the water supply in your community. Thirstin Glass DATES: You can begin this activity on September 18. You should complete it by September 22. OBJECTIVE: We have been learning about water and the water cycle in class. It is important for you to understand the impact you have on this cycle. Each person uses ...

Hughes, Mr.

2006-02-11

239

Thick titanium dioxide films for semiconductor photocatalysis  

Microsoft Academic Search

Thick paste TiO2 films are prepared and tested for photocatalytic and photoinduced superhydrophilic (PSH) activity. The films are effective photocatalysts for the destruction of stearic acid using near or far UV and all the sol–gel films tested exhibited a quantum yield for this process of typically 0.15%. These quantum yields are significantly greater (4–8-fold) than those for titania films produced

Andrew Mills; George Hill; Sharan Bhopal; Ivan P. Parkin; Shane A. O’Neill

2003-01-01

240

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.

241

Earth's Water:Ground Water  

NSDL National Science Digital Library

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

242

Water Purifier  

NASA Technical Reports Server (NTRS)

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

1992-01-01

243

Photocatalytic water splitting for hydrogen generation on cubic, orthorhombic, and tetragonal KNbO3 microcubes.  

PubMed

Potassium niobate (KNbO3) microcubes with orthorhombic and tetragonal phases were hydrothermally prepared and characterized by powder X-ray diffraction, nitrogen adsorption-desorption, micro-Raman spectroscopy, Fourier transform infrared spectroscopy, diffuse reflectance UV-visible spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy. The photoreactivity of the as-prepared KNbO3 samples was evaluated regarding the hydrogen evolution from aqueous methanol under UV, and the results were compared with that of cubic KNbO3 microcubes. The photocatalytic reactivity was shown to be phase-dependent, following the order cubic > orthorhombic > tetragonal. Insight into the phase-dependent photocatalytic properties was gained by first-principles density functional calculations. The best photocatalytic performance of cubic KNbO3 is ascribed to it having the highest symmetry in the bulk structure and associated unique electronic structure. Further, the surface electronic structure plays a key role leading to the discrepancy in photoreactivity between orthorhombic and tetragonal KNbO3. The results from this study are potentially applicable to a range of perovskite-type mixed metal oxides useful in water splitting as well as other areas of heterogeneous photocatalysis. PMID:23873181

Zhang, Tingting; Zhao, Kun; Yu, Jiaguo; Jin, Jian; Qi, Yang; Li, Huiquan; Hou, Xinjuan; Liu, Gang

2013-09-21

244

Branding water.  

PubMed

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

Dolnicar, Sara; Hurlimann, Anna; Grün, Bettina

2014-06-15

245

Wasted waters.  

PubMed

This article presents the increasing mismanagement of water as a result of increasing delivery of water volume, water pollution, and water wasting. One example of water mismanagement is irrigation, through which 67% of water is withdrawn from the hydrological cycle. In addition, reports from European communities reveal that pesticides from agriculture worsen the existing underground pollution. Furthermore, a 25% drop in land productivity was observed in Africa due to erosion, salinization, water logging, and desertification. Also, 23% of withdrawn water goes to industries, which are the major polluters. Since 1900 about 250,000 tons of cadmium have been produced worldwide, which eventually enter and harm the aquatic and terrestrial ecosystems. Moreover, high mercury levels were observed in Malaysia's Kelang River in the late 1980s, and river pollution in Thailand and Malaysia is recorded to be 30-100 times higher than accepted levels. Aside from that, the human race must also understand that there is a connection between water scarcity and water quality. When there is water pollution, it is expected that many people will suffer diarrheal diseases and intestinal parasite infections, which will further increase the mortality rate to 3.3 million per year. Realizing the severity of the problem, it is suggested that the human race must learn to recycle water like stormwater to prevent scarcity with drinking water. PMID:12295784

Niemczynowicz, J

1996-11-01

246

Controllable extracellular biosynthesis of bismuth sulfide nanostructure by sulfate-reducing bacteria in water-oil two-phase system.  

PubMed

Due to strong hydrolysis of Bi(3+) as precursor in aqueous media, there are no reports on biosynthesis of bismuth sulfide (Bi2 S3 ) nanomaterials. In this work, the water-oil two-phase system was used to biosynthesize the Bi2 S3 nanomaterials based on the coupling reaction of biological reduction and chemical precipitation process for the first time. The results showed that the water-oil two-phase system successfully eliminated hydrolysis of the Bi(3+) and controllably and extracellularly fabricated the Bi2 S3 crystal with high purity. The nanorods with diameter of about 100 nm and length of about 1.0 ?m were attained under high dose of lactic acid and SO4 (2-) ; while low dose obtained the nanobundles consisted of nanoneedles with tip diameter of 10-20 nm and length of about 5.0-10.0 ?m. The Bi2 S3 nanorods as photocatalyst almost completely degraded methylene blue from solution within 12 h; whereas the Bi2 S3 nanobundles removed about 87% of the dye. The amount of the Bi2 S3 nanorods decreased by 48% due to photocorrosion, whereas 52% with the nanobundles. The Bi2 S3 nanorods had relatively higher photocatalysis activity and slightly stronger photocorrosion resistance than the Bi2 S3 nanobundles. PMID:24616368

Yue, Lei; Wu, Ying; Liu, Xin; Xin, Baoping; Chen, Shi

2014-01-01

247

Water Matters  

Microsoft Academic Search

The origin of water on Earth and the other rocky planets is uncertain. There are problems with commonly accepted sources such as comets and asteroids. We explore adsorption of water onto grains in the accretion disk as a source.

M. J. Drake; M. Stimpfl

2007-01-01

248

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

249

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

250

Saline Water  

NSDL National Science Digital Library

This resource introduces students to the idea of saline water. Topics include how saline water is defined and how dissolved salt concentrations are expressed (parts per million). Parameters for the various ranges of salinity (fresh to highly saline, or seawater) are also presented, and there is a brief discussion of water quality considerations regarding saline water. Links to additional information are embedded in the text.

2011-09-30

251

Saline Water  

NSDL National Science Digital Library

This resource introduces students to the idea of saline water. Topics include how saline water is defined and how dissolved salt concentrations are expressed (parts per million). Parameters for the various ranges of salinity (fresh to highly saline, or seawater) are also presented, and there is a brief discussion of water quality considerations regarding saline water. Links to additional information are embedded in the text.

252

Falling Water  

NSDL National Science Digital Library

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

Integrated Teaching And Learning Program

253

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

254

Water Resources  

NASA Technical Reports Server (NTRS)

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

Salomonson, V. V.

1973-01-01

255

Water Filtration  

NSDL National Science Digital Library

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

Center For Engineering Educational Outreach

256

WATER FROM (WASTE)WATER -- THE DEPENDABLE WATER RESOURCE  

Microsoft Academic Search

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

Takashi Asano

257

Water Conservation  

NSDL National Science Digital Library

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

258

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

E-print Network

catalyze ionomer destruction) ­ Need to distinguish between degradation of different components (ionomer/catalyst on Pt and candidate non-PGM catalysts ­ Discussion of possible role of specific adsorption of hydroxide-PGMs. ­ Flooding ­ ionomer/catalyst ­ Role of CO2 as a poison based on electro-migration (carbonate species

259

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

260

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.; Lucas, C. A.; Wang, G.; Ross, P. N.; Markovic, N. M.; Materials Science Division; Univ. of California at Berkeley; Technical Univ.; Univ. of Liverpool; Univ. of South Carolina

2007-01-01

261

Volcano plots in hydrogen electrocatalysis - uses and abuses.  

PubMed

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

Quaino, Paola; Juarez, Fernanda; Santos, Elizabeth; Schmickler, Wolfgang

2014-01-01

262

Beyond the volcano limitations in electrocatalysis--oxygen evolution reaction.  

PubMed

Oxygen evolution catalysis is restricted by the interdependence of adsorption energies of the reaction intermediates and the surface reactivity. The interdependence reduces the number of degrees of freedom available for catalyst optimization. Here it is demonstrated that this limitation can be removed by active site modification. This can be achieved on ruthenia by incorporation of Ni or Co into the surface, which activates a proton donor-acceptor functionality on the conventionally inactive bridge surface sites. This enhances the actual measured oxygen evolution activity of the catalyst significantly compared to conventional ruthenia. PMID:24671166

Halck, Niels Bendtsen; Petrykin, Valery; Krtil, Petr; Rossmeisl, Jan

2014-07-21

263

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

264

Constant chemical potential approach for quantum chemical calculations in electrocatalysis.  

PubMed

In order to simulate electrochemical reactions in the framework of quantum chemical methods, density functional theory, methods can be devised that explicitly include the electrochemical potential. In this work we discuss a Grand Canonical approach in the framework of density functional theory in which fractional numbers of electrons are used to represent an open system in contact with an electrode at a given electrochemical potential. The computational shortcomings and the additional effort in such calculations are discussed. An ansatz for a SCF procedure is presented, which can be applied routinely and only marginally increases the computational effort of standard constant electron number approaches. In combination with the common implicit solvent models this scheme can become a powerful tool, especially for the investigation of omnipresent non-faradaic effects in electrochemistry. PMID:24991504

Schneider, Wolfgang B; Auer, Alexander A

2014-01-01

265

Electrocatalysis of fuel cell reactions: Investigation of alternate electrolytes  

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

266

Mutation detection by electrocatalysis at DNA-modified electrodes  

Microsoft Academic Search

Detection of mutations and damaged DNA bases is important for the early diagnosis of genetic disease. Here we describe an electrocatalytic method for the detection of single-base mismatches as well as DNA base lesions in fully hybridized duplexes, based on charge transport through DNA films. Gold electrodes modified with preassembled DNA duplexes are used to monitor the electrocatalytic signal of

Elizabeth M. Boon; Donato M. Ceres; Thomas G. Drummond; Michael G. Hill; Jacqueline K. Barton

2000-01-01

267

Bimetallic and Trimetallic Nanoparticles for Fuel Cell Electrocatalysis  

SciTech Connect

Theoretical, high level ab initio investigations on representative clusters as well as on extended systems are conducted to determine the electronic, geometric, and thermodynamic factors that determine catalytic and electrocatalytic behavior, focusing in the reduction of oxygen in acid medium. The study of adsorption and reaction processes generates the information needed for force field development to be used in the analysis of nanocatalyst particles, their support, and their environment through large-scale molecular dynamics simulations, which include collective effects at the nanosecond time scale. Ab initio molecular dynamics simulations are used to explore reaction mechanisms, and this technique along with transition state theory calculations allows us to obtain the information needed about activation energies and estimates of the rate constants. Dynamic Monte Carlo simulations combine the results of the first three sets of studies yielding kinetics information within a time scale in the range of seconds and length scales of the order of hundreds of nanometers, including nanocatalyst/support/environment.

Perla B. Balbuena; Jorge M. Seminario

2005-10-31

268

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

269

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

2012-05-23

270

Preparation and performance of nanosized tungsten carbides for electrocatalysis  

Microsoft Academic Search

The principle of the intermittent microwave heating (IMH) method and the details on the working procedure for prepare nanosized materials were presented along with the comparison to the traditional continuous microwave heating (CMH) method. The nanosized tungsten carbides were synthesized as an example by this novel method. It produced WC with the average particle size of 21.4nm at the procedure

Pei Kang Shen; Shibin Yin; Zihui Li; Chan Chen

2010-01-01

271

Characterizing nano-scale electrocatalysis during partial oxidation of methane  

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

272

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

273

EXTENSION WATER SUMMIT PRIORITY: WATER CONSERVATION  

E-print Network

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

Kane, Andrew S.

274

Electrocatalysis: Controllable Synthesis and Enhanced Electrocatalysis of Iron-based Catalysts Derived From Electrospun Nanofibers (Small 20/2014).  

PubMed

Porous carbon nanofibers containing iron and nitrogen, represented by the cubes containing the nanofibers in the image, are developed by J. Luo, J. Zhu, and co-workers to efficiently catalyze the oxygen reduction reaction in fuel cells. As described on page 4072, the nanofibers are produced from electrospun polymer fibers that are denoted by the flower-like fiber bundle with an open end in the image. When the oxygen bubbles meet the nanofibers, energies ('lightning' from the bubble centers) can be generated. PMID:25333220

Yan, Xingxu; Gan, Lin; Lin, Yuh-Chen; Bai, Lu; Wang, Tuo; Wang, Xiangqing; Luo, Jun; Zhu, Jing

2014-10-01

275

Ground Water Ground Sky Sky Water Vegetation Ground Vegetation Water  

E-print Network

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

Chen, Tsuhan

276

Water Filter  

NASA Technical Reports Server (NTRS)

A compact, lightweight electrolytic water sterilizer available through Ambassador Marketing, generates silver ions in concentrations of 50 to 100 parts per billion in water flow system. The silver ions serve as an effective bactericide/deodorizer. Tap water passes through filtering element of silver that has been chemically plated onto activated carbon. The silver inhibits bacterial growth and the activated carbon removes objectionable tastes and odors caused by addition of chlorine and other chemicals in municipal water supply. The three models available are a kitchen unit, a "Tourister" unit for portable use while traveling and a refrigerator unit that attaches to the ice cube water line. A filter will treat 5,000 to 10,000 gallons of water.

1982-01-01

277

Computerized Waters  

E-print Network

Microsoft Windows,Dr. Ralph Wurbs has designed a computer mod- eling system that has changed the way Texas manages its rivers, streams and reservoirs. The modeling system called Water Rights Availability Package, or WRAP for short, is a set of computer... water use and assesses the impacts on all the other water uses in the river basin. #2; Dr. Ralph Wurbs, professor of civil engineering, examines the Texas river basin maps with Richard Hoffpauir, graduate student. These maps were developed, using...

Wythe, Kathy

2006-01-01

278

Water Quality  

NSDL National Science Digital Library

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

Service, National P.

2011-08-20

279

Water Jetting  

NASA Technical Reports Server (NTRS)

Hi-Tech Inc., a company which manufactures water jetting equipment, needed a high pressure rotating swivel, but found that available hardware for the system was unsatisfactory. They were assisted by Marshall, which had developed water jetting technology to clean the Space Shuttles. The result was a completely automatic water jetting system which cuts rock and granite and removes concrete. Labor costs have been reduced; dust is suppressed and production has been increased.

1985-01-01

280

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

NASA Astrophysics Data System (ADS)

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

Vagnini, Michael Thomas

281

WATER CONSERVATION  

E-print Network

distribution is unlimited. MIL-HDBK-1165 Water conservation, maximizing the efficient use of water resources, is rapidly becoming a critical part of many military operations as more and more demands are placed upon existing water supplies. In order to remain a good neighbor and preserve the environment in which we live, engineers throughout the Department of Defense are frequently called upon to review the beneficial use of their water resources. This military handbook provides numerous methods to increase water efficiency and details the requirements of Executive Order 12902 as it relates to water conservation within the Department of Defense. In addition, this handbook also includes, in its appendices, procedures for submitting water conservation projects for central funding programs. ii MIL-HDBK-1165 FOREWORD This handbook is designed to provide guidance to the installation energy or facilities manager and project designers in the area of water conservation. This handbook is intended to assist installations in reducing their water consumption and thereby assist in complying with the provisions of Executive Order 12902. Recommendations for improvement are encouraged from within the Navy, other government agencies, and the private sector and should be furnished on the DD Form 1426 provided inside the back

Distribution Statement

1997-01-01

282

Water Filters  

NASA Technical Reports Server (NTRS)

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

1993-01-01

283

Water pumps  

PubMed Central

The transport of water across epithelia has remained an enigma ever since it was discovered over 100 years ago that water was transported across the isolated small intestine in the absence of osmotic and hydrostatic pressure gradients. While it is accepted that water transport is linked to solute transport, the actual mechanisms are not well understood. Current dogma holds that active ion transport sets up local osmotic gradients in the spaces between epithelial cells, the lateral intercellular spaces, and this in turn drives water transport by local osmosis. In the case of the small intestine, which in humans absorbs about 8 l of water a day, there is no direct evidence for either local osmosis or aquaporin gene expression in enterocytes. Intestinal water absorption is greatly enhanced by glucose, and this is the basis for oral rehydration therapy in patients with secretory diarrhoea. In our studies of the intestinal brush border Na+-glucose cotransporter we have obtained evidence that there is a direct link between the transport of Na+, glucose and water transport, i.e. there is cotransport of water along with Na+ and sugar, that will account for about 50 % of the total water transport across the human intestinal brush border membrane. In this short review we summarize the evidence for water cotransport and propose how this occurs during the enzymatic turnover of the transporter. This is a general property of cotransporters and so we expect that this may have wider implications in the transport of water and other small polar molecules across cell membranes in animals and plants. PMID:12096049

Loo, Donald D F; Wright, Ernest M; Zeuthen, Thomas

2002-01-01

284

Virginia's Waters.  

ERIC Educational Resources Information Center

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

Sevebeck, Kathryn P.; And Others

285

Water Filter  

NSDL National Science Digital Library

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

Boston, Wgbh

2002-01-01

286

Water Safety  

MedlinePLUS

... All kids need to be supervised in the water, no matter what their swimming skill levels. And infants, toddlers, and weak swimmers should have an adult swimmer within arm's reach to provide ... a child is near water. Check the weight and size recommendations on the ...

287

Water Filters  

NASA Technical Reports Server (NTRS)

A compact, lightweight electrolytic water filter generates silver ions in concentrations of 50 to 100 parts per billion in the water flow system. Silver ions serve as effective bactericide/deodorizers. Ray Ward requested and received from NASA a technical information package on the Shuttle filter, and used it as basis for his own initial development, a home use filter.

1987-01-01

288

Mixing Water  

NSDL National Science Digital Library

The purpose of this assessment probe is to elicit students' ideas about temperature and energy transfer. The probe is designed to find out whether students recognize that a transfer of energy from the warm water to the cool water occurs until they reach the same temperature. Additionally, students' explanations reveal whether they use an addition, subtraction, or averaging strategy to determine the resulting temperature.

Eberle, Francis; Tugel, Joyce; Keeley, Page

2007-01-01

289

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

290

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

291

Sinking Water  

NSDL National Science Digital Library

In this experiment, learners float colored ice cubes in hot and cold water. They compare the behavior of the melting ice cubes to understand how temperature is related to ocean currents and how temperature changes water density. The printable eight-page handout includes a series of inquiry-based questions to get learners thinking about how and why water temperature changes along with depth. Illustrated experiment directions and a worksheet help learners use the experiment results to gain a deeper understanding of buoyancy and density.

History, American M.

2002-01-01

292

Water Purification  

NASA Technical Reports Server (NTRS)

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

1994-01-01

293

Fragile Waters  

NSDL National Science Digital Library

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

Museum, University O.

2014-01-28

294

Synthesis of Pt doped Bi2O3/RuO2 photocatalysts for hydrogen production from water splitting using visible light.  

PubMed

This study was focused on the preparation of modified bismuth oxide photocatalysts, including Ru and Pt doped Bi2O3, using sonochemically assisted method to enhance their photocatalytic activity. The crystalline phase composition and surface structure of Bi2O3 photocatalysts were examined using SEM, XRD, UV-visible spectroscopy, and XPS. Optical characterizations have indicated that the Bi2O3 presents the photoabsorption properties shifting from UV light region into visible light which is approaching towards the edge of 470 nm. According to the experimental results, visible-light-driven photocatalysis for water splitting with the addition of 0.3 M Na2SO3 and 0.03 M H2C2O4 as sacrificing agents demonstrates that Pt/Bi2O3-RuO2 catalyst could increase the amount of hydrogen evolution, which is around 11.6 and 14.5 micromol g(-1) h(-1), respectively. Plausible formation mechanisms of modified bismuth oxide and reaction mechanisms of photocatalytic water splitting have been proposed. PMID:22966683

Hsieh, S H; Lee, G J; Chen, C Y; Chen, J H; Ma, S H; Horng, T L; Chen, K H; Wu, J J

2012-07-01

295

Water Safety  

MedlinePLUS

... the boat is experienced and competent. Alcohol and water still don't mix. One third of boating deaths are alcohol related. Alcohol distorts our judgment no matter where we are — but that distortion is even ...

296

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

2014-05-22

297

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

298

Grabbing Water  

E-print Network

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

Reis, Pedro Miguel

299

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...

300

WATER ANALYSIS  

EPA Science Inventory

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

301

Water purification  

US Patent & Trademark Office Database

The invention provides an efficient method to purify an aqueous solution, typically mine drainage water, especially of anions and cations present in the aqueous solution as dissolved solids, the anions and cations are removed by treatment with a positively charged extractant having at least eight carbon atoms, whereby an unstable emulsion is formed; the unstable emulsion is allowed to break into an extract phase loaded with the anions and cations, and a water phase depleted in anions and cations; a floc inherently forms in the loaded extractant phase and then the loaded extractant phase and floc are separated from the purified water and treated to remove the anions and cations as concentrated useful products; the treated aqueous phase now reduced in anion and/or cation content is also separated from the emulsion as a purified aqueous solution. The extractant phase is preferably recycled. A continuous water purification process is provided.

2013-11-19

302

Sinking Water  

NSDL National Science Digital Library

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

303

Water separator  

NASA Technical Reports Server (NTRS)

An apparatus for separating liquids from gases or gaseous fluids is described. Features of the apparatus include: (1) the collection and removal of the moisture in the fluid is not dependent upon, or affected by gravity; (2) all the collected water is cyclically drained from the apparatus irrespective of the attitude of the separator; and (3) a fluid actuator is utilized to remove the collected water from the separator.

Dunn, W. F.; Austin, I. G. (inventors)

1964-01-01

304

Filtering Water  

NSDL National Science Digital Library

The first site related to water filtration is from the US Environmental Agency entitled EPA Environmental Education: Water Filtration (1 ). The two-page document explains the need for water filtration and the steps water treatment plants take to purify water. To further understand the process, a demonstration project is provided that illustrates these purification steps, which include coagulation, sedimentation, filtration, and disinfection. The second site is an interesting Flash animation called Filtration: How Does it Work (2 ) provided by Canada's Prairie Farm Rehabilitation Administration. Visitors will learn various types of filtration procedures and systems and the materials that are used such as carbon and sand. Next, from the National Science Foundation is a learning activity called Get Out the Gunk (3 ). Using just a few simple items from around the house, kids will be able to answer questions like "Does a filter work better with a lot of water rushing through, or a small trickle?" and "Does it make the water cleaner if you pour it through a filter twice?" The fourth Web site, Rapid Sand Filtration (4 ), is provided by Dottie Schmitt and Christie Shinault of Virginia Tech. The authors describe the process, which involves the flow of water through a bed of granular media, normally following settling basins in conventional water treatment trains to remove any particulate matter left over after flocculation and settling. Along with its thorough description, readers can view illustrations and photographs that further explain the process. The Vegetative Buffer Strips for Improved Surface Water Quality (5) Web site is provided by the Iowa State University Extension office. The document explains what vegetative buffer strips are, how they filter contaminants and sediment from surface water, how effective they are, and more. The sixth offering is a file called Infiltration Basins and Trenches (6) that is offered by the University of Wisconsin Extension. These structures are intended to collect water, have it infiltrate into the ground, and have it purified along the way. This document explains how effective they are at removing pollutants, how to install them, design guidelines, maintenance, and more. Next, from a site called Wilderness Survial.net is the Water Filtration Devices (7) page. Visitors read how to make a filtering system out of cloth, sand, crushed rock, charcoal, or a hollow log, although as is stated, the water still has to be purified. The last site, from the US Geological Survey, is called A Visit to a Wastewater-Treatment Plant: Primary Treatment of Wastewater (8). Although geared towards children, the site does a good job of explaining what happens at each stage of the treatment process and how pollutants are removed to help keep water clean. Everything from screening, pumping, aerating, sludge and scum removal, killing bacteria, and what is done with wastewater residuals is covered.

Brieske, Joel A.

2003-01-01

305

Electrocatalytic reduction of nitrate in water.  

PubMed

Nitrate (NO(3)(-)) contamination of groundwater is a common problem throughout intensive agricultural areas (nonpoint source pollution). Current processes (e.g., ion exchange, membrane separation) for NO(3)(-) removal have various disadvantages. The objective of this study was to evaluate an electrocatalytic reduction process to selectively remove NO(3)(-) from groundwater associated with small agricultural communities. A commercially available ELAT (E-Tek Inc., Natick, MA) carbon cloth with a 30% surface coated Rh (rhodium) (1microg x cm(-1)) was tested at an applied potential of -1.5 V versus standard calomel electrode (SCE) with a Pt auxiliary electrode. Electrocatalytic reduction process (electrolysis) of NO(3)(-) was tested with cyclic voltammetry (CV) in samples containing NO(3)(-) and 0.1M NaClO(4)(-). Nitrate and NO(2)(-) concentrations in test solutions and groundwater samples were analyzed by ion chromatography (IC). The presence of Rh on the carbon cloth surface resulted in current increase of 36% over uncoated carbon cloths. The electrocatalysis experiments using Rh coated carbon cloth resulted in reduction of NO(3)(-) and NO(2)(-) on a timescale of minutes. Nitrite is produced as a product, but is rapidly consumed upon further electrolysis. Field groundwater samples subjected to electrocatalysis experiments, without the addition of NaClO(4)(-) electrolyte, also exhibited removal of NO(3)(-) on a timescale of minutes. Overall, results suggest that at an applied potential of -1.5 V with respect to SCE, Rh coated carbon cloth can reduce NO(3)(-) concentrations in field groundwater samples from 73 to 39 mg/L (16.58 to 8.82 mg/L as N) on a timescale range of 40-60 min. The electrocatalytic reduction process described in this study may prove useful for removing NO(3)(-) and NO(2)(-) from groundwater associated with nonpoint source pollution. PMID:12727264

Peel, J W; Reddy, K J; Sullivan, B P; Bowen, J M

2003-05-01

306

ESW 2009: Water, Water Everywhere  

NASA Video Gallery

Water is all around us, and its importance to nearly every natural process on earth cannot be underestimated. It is vital to life, but it is also tightly coupled to climate, helping to carry heat f...

307

Drinking Water FAQ  

MedlinePLUS

... or ground water. Surface water collects in streams, rivers, lakes, and reservoirs. Ground water is water located ... protect drinking water and its sources, which include rivers, lakes, reservoirs, springs, and ground water wells. Top ...

308

Treatment of Well Water  

MedlinePLUS

... Pore Sizes Camping, Hiking, Travel Drinking Water Treatment & Sanitation for Backcountry & Travel Use Emergency Disinfection of Drinking ... Drinking Water Healthy Swimming / Recreational Water Global Water, Sanitation, & Hygiene Other Uses of Water Water-related Emergencies & ...

309

Private Ground Water Wells  

MedlinePLUS

... Pore Sizes Camping, Hiking, Travel Drinking Water Treatment & Sanitation for Backcountry & Travel Use Emergency Disinfection of Drinking ... Drinking Water Healthy Swimming / Recreational Water Global Water, Sanitation, & Hygiene Other Uses of Water Water-related Emergencies & ...

310

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...

311

Arnold Schwarzenegger WATER HEATERS AND HOT WATER  

E-print Network

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

312

Grabbing water  

E-print Network

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

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

2012-07-16

313

Troubling Waters  

NSDL National Science Digital Library

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

Carolyn J. Strange (freelance writer;)

2008-12-01

314

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

315

Energetic Water  

NSDL National Science Digital Library

In this activity, learners explore how hot and cold water move. Learners observe that temperature and density affect how liquids rise and fall. Learners also discover that although they can't see molecules with their eyes, they can demonstrate that molecules are always moving.

Workshop, Mission S.

2013-01-01

316

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

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

317

Arkansas Water Resources Center  

E-print Network

-800 Cooperating Agencies Arkansas Water Resources Center ARKANSAS SOIL & WATER CONSERVATION COMMISSION WASHINGTON COUNTY SOIL AND WATER CONSERVATION DISTRICT UNIVERSITY OF ARKANSAS Federal Assistance Project No. C Cooperating Agencies ARKANSAS WATER RESOURCES CENTER ARKANSAS SOIL & WATER CONSERVATION COMMISSION WASHINGTON

Soerens, Thomas

318

Earth's Water  

NSDL National Science Digital Library

The total amount of water on Earth, the places in which it is found and the percentages of fresh vs. salt are examined in this lesson. A short demonstration allows students to visualize the percentage differences and a coloring exercise illustrates locations. This lesson uses the 5E instructional model. All background information, student worksheets and images/photographs/data are included in these downloadable sections: Teacher's Guide, Student Capture Sheet and PowerPoint Presentation.

319

Troubled Waters  

NSDL National Science Digital Library

In this activity, students explore the influences of different parameters on the environmental quality of a river system. They will run a computer model of a river system, interpret graphs, and adjust model parameters such as wind speed, sewage load, and other variables to determine their effects on water quality. For teachers, there are additional background materials, teaching tips, evaluation methods, and links to national standards.

Farmer, John

320

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.

321

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

322

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

323

Water Resources Data, Louisiana, Water Year 2001  

USGS Publications Warehouse

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

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

2002-01-01

324

Water Resources Data, Louisiana, Water Year 2002  

USGS Publications Warehouse

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

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

2003-01-01

325

Water Resources Data, Louisiana, Water Year 2000  

USGS Publications Warehouse

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

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

2001-01-01

326

Water Withdrawals and Water Use in Michigan  

E-print Network

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

327

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE  

E-print Network

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

Nebraska-Lincoln, University of

328

Water Sustainability Program Challenges to Sustainable Water  

E-print Network

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

Cushing, Jim. M.

329

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE  

E-print Network

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

Nebraska-Lincoln, University of

330

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

331

Ground water provides drinking water, irrigation for  

E-print Network

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

Saldin, Dilano

332

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.

333

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE  

E-print Network

of the National Environmental Policy Act of 1969, water resources professionals squarely faced the fact that water current pricing policies and legal structures. In analyzing energy-water relationships, wastefulWATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE 212 AGRICULTURAL ENGINEERING BUILDING

Nebraska-Lincoln, University of

334

Water, Water Everywhere! [Narrator] Water, Water Everywhere Water is all around us, and its importance to nearly every process  

E-print Network

Water, Water Everywhere! [Narrator] Water, Water Everywhere Water is all around us, and its naturally as a liquid, gas, and solid. The process by which water moves around the Earth, from the ocean to the atmosphere to the land, and back to the ocean, is called the water cycle. Water regulates climate, storing

Waliser, Duane E.

335

Water Purification  

NASA Technical Reports Server (NTRS)

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

1992-01-01

336

Fresh Water  

NSDL National Science Digital Library

You will use online resources to learn about freshwater ecosystems, the critters that live in them and the effect we have on them. You may choose to print this page out to assist you in answering questions. In studying fresh water, we will be looking at three different ecosystems: Streams and Rivers; Ponds and Lakes; and Wetlands. The following site contains information about all 3. Answer the questions on loose-leaf or in an MS Word document, to be printed. Freshwater Ecosystems (title provided or enhanced by cataloger) After clicking the link above, click on "Rivers ...

Bionagy

2008-10-25

337

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.

338

Water Source Books  

NSDL National Science Digital Library

Online curriculum guides for K-12 with over 324 activities related to wetlands, coastal waters, and water resources. Each grade section (K-2, 3-5, 5-8, and 9-12) is divided into five chapters: Introduction to Water, Drinking Water and Wastewater Treatment, Surface Water Resources, Ground Water Resources, and Wetlands and Coastal Waters.

339

Principles of Water Quality  

SciTech Connect

CONTENTS: Introduction to Water Quality Concepts. Natural Environmental Processes. Toxic Metals as Factors in Water Quality. Refractory Organic Compounds. Nutrients, Productivity, and Eutrophication. Microbes and Water Quality. Thermal Effects and Water Quality. Air Quality. Water Quality Interactions. Introduction to Water Quality Modeling. Water Quality Standards, and Management Approaches.

Waite, T.D.

1984-01-01

340

Water Source Books  

NSDL National Science Digital Library

Online curriculum guides for K-12 with over 324 activities related to wetlands, coastal waters, and water resources. Each grade section (K-2, 3-5, 5-8, and 9-12) is divided into five chapters: Introduction to Water, Drinking Water and Wastewater Treatment, Surface Water Resources, Ground Water Resources, and Wetlands and Coastal Waters.

2010-08-06

341

Be Water Wise.  

ERIC Educational Resources Information Center

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

Birch, Sandra K.; Pettus, Alvin M.

342

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

343

Water resources data, Tennessee, water year 2004  

USGS Publications Warehouse

Water resources data for the 2004 water year for Tennessee consists of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; and water levels and water quality of ground water. This report contains records for water discharge at 107 gaging stations; stage only for 1 gaging station, elevation and contents for 32 lakes reservoirs; water quality at 18 gaging stations and 17 wells; and water levels for 8 observation wells; and 1 precipitation station. Also included are data for 84 crest stage partial-record stations. Additional water data were collected at various stream sites not involved in the systematic data-collection program, and are published as miscellaneous measurements and analyses. These data represent the part of the National Water Data System operated by the US Geological Survey and cooperating State and Federal agencies in Tennessee.

Flohr, D. F.; Garrett, J. W.; Hamilton, J. T.; Phillips, T. D.

2005-01-01

344

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

345

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

ScienceCinema

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

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

2011-11-02

346

Improved water does not mean safe water  

NASA Astrophysics Data System (ADS)

This work presents a model for estimating global access to drinking water that meets World Health Organization (WHO) water quality guidelines. The currently accepted international estimate of global access to safe water, the WHO and United Nations Children's Fund's (UNICEF) Joint Monitoring Program (JMP) report, estimates the population with access to water service infrastructure that is classified as improved and unimproved. The JMP report uses access to improved water sources as a proxy for access to safe water, but improved water sources do not always meet drinking water quality guidelines. Therefore, this report likely overestimates the number of people with access to safe water. Based on the JMP estimate, the United Nations has recently announced that the world has reached the Millennium Development Goal (MDG) target for access to safe water. Our new framework employs a statistical model that incorporates source water quality, water supply interruptions, water storage practices, and point of use water treatment to estimate access to safe water, resulting in a figure that is lower than the JMP estimate of global access to safe water. We estimate that at least 28% of the world does not have access to safe water today, as compared to the JMP estimate of 12%. These findings indicate that much more work is needed on the international scale to meet the MDG target for access to safe water.

MacDonald, L. H.; Guo, Y.; Schwab, K. J.

2012-12-01

347

Water resources data, Nebraska, water year 2004  

USGS Publications Warehouse

The Nebraska water resources data report for water year 2004 includes records of stage, discharge, and water quality of streams; water elevation and/or contents of lakes and reservoirs; and water levels and quality of ground water in wells. This report contains records of stream stage for 3 stations; stream discharge for 101 continuous and 5 crest-stage gaging stations, and 6 miscellaneous sites; stream water quality for 7 gaging stations and 40 miscellaneous sites; water elevation and/or contents for 2 lakes and 1 reservoir; ground-water levels for 74 observation wells; and ground-water quality for 200 wells. These data represent that part of the National Water Data System collected in and near Nebraska by the U.S. Geological Survey and cooperating Federal, State, and local agencies.

compiled by Hitch, D. E.; Soensken, P. J.; Sebree, S. K.; Wilson, K. E.; Walczyk, V. C.; Drudik, R. A.; Miller, J. D.; Hull, S. H.

2005-01-01

348

Drinking Water Problems: Lead  

E-print Network

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

Dozier, Monty; McFarland, Mark L.

2004-02-20

349

Source Water Protection  

MedlinePLUS

... comes from ground water, streams, rivers, springs or lakes in a watershed. Although most water requires some ... Education & Training Grants & Funding Laws & Regulations Our Waters Pollution Prevention & Control Resources & Performance Science & Technology Water Infrastructure ...

350

Land and water snails  

NSDL National Science Digital Library

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

Olivia Worland (Purdue University;Biological Sciences)

2008-06-03

351

EXPLANATION Water withdrawals,  

E-print Network

withdrawals Surface-water withdrawals Groundwater withdrawals West­east division for this report and State, 2005. Estimated Use of Water in the United States in 2005 USGS Water-Science School -- http://ga.water.usgs

352

WATER MANAGEMENT & HYDROLOGICAL SCIENCE  

E-print Network

WATER MANAGEMENT & HYDROLOGICAL SCIENCE External Review Water Management and Hydrological Science Graduate Program Self Study October 2012 #12;#12;WATER MANAGEMENTWATER MANAGEMENT & HYDROLOGICAL SCIENCE& HYDROLOGICAL SCIENCE External Review Water Management and Hydrological Science Graduate Program Self Study

353

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, ...

354

Autoionization of water  

NSDL National Science Digital Library

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

Merlic, Craig; Fam, Barry

355

Drinking Water Problems: Copper  

E-print Network

management strategy, consider treating your water or seeking an alternative drink- ing-water supply such as bottled water. Treatment options for reducing copper concentrations in water include (1) reverse osmosis, (2) distillation or (3) ion exchange. Reverse... management strategy, consider treating your water or seeking an alternative drink- ing-water supply such as bottled water. Treatment options for reducing copper concentrations in water include (1) reverse osmosis, (2) distillation or (3) ion exchange. Reverse...

Dozier, Monty; McFarland, Mark L.; Lesikar, Bruce J.

2006-01-25

356

EXTENSION WATER SUMMIT PRIORITY: WATER QUALITY  

E-print Network

EXTENSION WATER SUMMIT PRIORITY: WATER QUALITY Leadership Team Subcommittee: Mark Clark Karl Havens BJ Jarvis Kelly Morgan Ramesh Reddy #12;Water Quality ­ Situation (resources) Florida has extensive and diverse water resources 54,836 miles of rivers and streams 1.8 million acres of lakes, reservoirs

Kane, Andrew S.

357

Household Water Quality Home Water Quality Problems  

E-print Network

Household Water Quality Home Water Quality Problems­ Causes and Treatments Blake Ross, Extension Many areas have water containing impurities from natural or artificial sources. These impurities may cause health problems, damage equipment or plumbing, or make the water undesirable due to taste, odor

Liskiewicz, Maciej

358

WATER RESOURCES ,'JEBRASKA WATER RESOURCES RESEARCH INSTITUTE  

E-print Network

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

Nebraska-Lincoln, University of

359

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE  

E-print Network

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

Nebraska-Lincoln, University of

360

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE  

E-print Network

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

Nebraska-Lincoln, University of

361

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE  

E-print Network

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

Nebraska-Lincoln, University of

362

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE  

E-print Network

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

Nebraska-Lincoln, University of

363

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE  

E-print Network

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

Nebraska-Lincoln, University of

364

WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE  

E-print Network

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

Nebraska-Lincoln, University of

365

Virtual water trade and world water resources.  

PubMed

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

Oki, T; Kanae, S

2004-01-01

366

EPANET water quality model  

Microsoft Academic Search

EPANET represents a third generation of water quality modeling software developed by the U.S. EPA's Drinking Water Research Division, offering significant advances in the state of the art for network water quality analysis. EPANET performs extended period simulation of hydraulic and water quality behavior within water distribution systems. In addition to substance concentration, water age and source tracing can also

Rossman

1993-01-01

367

DISINFECTION OF WATER: DRINKING WATER, RECREATIONAL WATER, AND WASTEWATER  

EPA Science Inventory

This chapter describes and categorizes the methodology used for disinfection of drinking water, recreational water and wastewater including wastewater sludges. It largely is a literature summary and references articles covering the years of 1939 through 1999, with a few reference...

368

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.

369

Molecular Structure of Water  

NSDL National Science Digital Library

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

2002-08-14

370

Water Resources Data, Alabama, Water Year 2005  

USGS Publications Warehouse

Water resources data for the 2005 water year for Alabama consist of records of stage, discharge, and water quality of streams; stages and contents of lakes and reservoirs; and water levels in wells. This report includes records on both surface and ground water in the State. Specifically, it contains: (1) discharge records for 131 streamflow-gaging stations and 23 partial-record or miscellaneous streamflow stations; (2) stage and content records for 14 lakes and reservoirs and stage at 44 stations; (3) water-quality records for 125 streamflow-gaging stations and 67 ungaged streamsites; (4) water temperature at 179 surface-water stations; (5) specific conductance at 180 stations; (6) dissolved oxygen at 17 stations; (7) turbidity at 52 stations; (8) sediment data at 2 stations; (9) water-level records for 2 recording observation wells; and (10) water-quality records for 6 ground-water stations. Also included are lists of active and discontinued continuous-record surface-water-quality stations, and partial-record and miscellaneous surface- water-quality stations. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating Federal, State, and local agencies in Alabama.

Psinakis, W. L.; Lambeth, D. S.; Stricklin, V. E.; Treece, M. W.

2006-01-01

371

Water Resources Data, Alabama, Water Year 2004  

USGS Publications Warehouse

Water resources data for the 2004 water year for Alabama consist of records of stage, discharge, and water quality of streams; stages and contents of lakes and reservoirs; and water levels in wells. This report includes records on both surface and ground water in the State. Specifically, it contains: (1) discharge records for 131 streamflow-gaging stations, for 19 partial-record or miscellaneous streamflow stations; (2) stage and content records for 16 lakes and reservoirs and stage at 44 stations; (3) water-quality records for 21 streamflow-gaging stations, for 11 ungaged streamsites, and for 1 precipitation stations; (4) water temperature at 20 surface-water stations; (5) specific conductance and dissolved oxygen at 20 stations; (6) turbidity at 5 stations; (7) sediment data at 6 stations; (8) water-level records for 2 recording observa-tion wells; and (9) water-quality records for 6 ground-water stations. Also included are lists of active and discontinued continuous-record surface-water-quality stations, and partial-record and miscellaneous sur-face-water-quality stations. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating Federal, State, and local agencies in Alabama.

Psinakis, W. L.; Lambeth, D. S.; Stricklin, V. E.; Treece, M. W.

2005-01-01

372

Water Resources Data, Alabama, Water Year 2002  

USGS Publications Warehouse

Water resources data for the 2002 water year for Alabama consist of records of stage, discharge, and water quality of streams; stages and contents of lakes and reservoirs; and water levels in wells. This report includes records on both surface and ground water in the State. Specifically, it contains: (1) discharge records for 131 streamflow-gaging stations, for 41 partial-record or miscellaneous streamflow stations; (2) stage and content records for 14 lakes and reservoirs and stage at 47 stations; (3) water-quality records for 12 streamflow-gaging stations, for 17 ungaged streamsites, and for 2 precipitation stations; (4) water temperature at 14 surfacewater stations; (5) specific conductance and dissolved oxygen at 12 stations; (6) turbidity at 3 stations; (7) sediment data at 6 stations; (8) water-level records for 2 recording observation wells; and (9) water-quality records for 21 ground-water stations. Also included are lists of active and discontinued continuous-record surface-water-quality stations, and partial-record and miscellaneous surface-water-quality stations. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating Federal, State, and local agencies in Alabama.

Pearman, J. L.; Stricklin, V. E.; Psinakis, W. L.

2003-01-01

373

Water Resources Data, Alabama, Water Year 2003  

USGS Publications Warehouse

Water resources data for the 2003 water year for Alabama consist of records of stage, discharge, and water quality of streams; stages and contents of lakes and reservoirs; and water levels in wells. This report includes records on both surface and ground water in the State. Specifically, it contains: (1) discharge records for 130 streamflow-gaging stations, for 29 partial-record or miscellaneous streamflow stations; (2) stage and content records for 14 lakes and reservoirs and stage at 46 stations; (3) water-quality records for 12 streamflow-gaging stations, for 29 ungaged streamsites, and for 1 precipitation stations; (4) water temperature at 12 surfacewater stations; (5) specific conductance and dissolved oxygen at 12 stations; (6) turbidity at 3 stations; (7) sediment data at 6 stations; (8) water-level records for 2 recording observation wells; and (9) water-quality records for 9 ground-water stations. Also included are lists of active and discontinued continuous-record surface-water-quality stations, and partial-record and miscellaneous surface-water-quality stations. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating Federal, State, and local agencies in Alabama.

Psinakis, W. L.; Lambeth, D. S.; Stricklin, V. E.; Treece, M. W.

2004-01-01

374

Water Remediation Lab  

NSDL National Science Digital Library

Students measure the effectiveness of water filters in purifying contaminated water. They prepare test water by creating different concentrations of bleach (chlorine-contaminated) water. After passing the contaminated water through commercially available Brita® water filters designed to purify drinking water, students determine the chlorine concentration of the purified water using chlorine test strips and measure the adsorption of chlorine onto activated carbon over time. They graph and analyze their results to determine the effectiveness of the filters. The household active carbon filters used are one example of engineer-designed water purification systems.

GK-12 Program,

375

Arkansas Water Resources Center  

E-print Network

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

Soerens, Thomas

376

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."

377

Water Regulation I. Osmoregulation  

E-print Network

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

Dever, Jennifer A.

378

Water Regulation I. Osmoregulation  

E-print Network

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

Dever, Jennifer A.

379

Water Basins Civil Engineering  

E-print Network

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

Provancher, William

380

Grains, Water Introduction  

E-print Network

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

Wirosoetisno, Djoko

381

Update: Nebraska's Integrated Water  

E-print Network

potential effects of climate variability on water supply #12;Statewide Water Use and Supply · UtilizeUpdate: Nebraska's Integrated Water Management Planning Greater Platte River Basins Symposium of hydrologically connected water supplies #12;Republican River Republican River Basin Water Supply 0 200 400 600

Nebraska-Lincoln, University of

382

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

383

Water in confined geometries  

Microsoft Academic Search

The dynamics of water molecules in the vicinity of a hydrophilic interface is modified as compared to that of bulk water. Recent experiments performed in porous silica show that water dynamics is well described by a stretched-exponential intermediate-scattering function. The behaviour of confined water is similar to that of supercooled water at lower (≈ 30 K) temperature. This temperature shift

J. Teixeira; J.-M. Zanotti; M.-C. Bellissent-Funel; S.-H. Chen

1997-01-01

384

Water in confined geometries  

Microsoft Academic Search

The dynamics of water molecules in the vicinity of a hydrophilic interface is modified as compared to that of bulk water. Recent experiments performed in porous silica show that water dynamics is well described by a stretched-exponential intermediate-scattering function. The behaviour of confined water is similar to that of supercooled water at lower (? 30 K) temperature. This temperature shift

J. Teixeira; J.-M. Zanotti; M.-C. Bellissent-Funel; S.-H. Chen

1997-01-01

385

Water Governance and Legislation  

NSDL National Science Digital Library

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

2003-07-31

386

Water Resources Policy & Economics  

E-print Network

Water Resources Policy & Economics FOR 4984 Selected Course Topics · Appropriative and riparian · Surface water-groundwater management · Water quality regulations · Water markets · Economic and policy policies and laws that govern water use as well as economic and policy analysis tools that can be used

Buehrer, R. Michael

387

Arkansas Water Resources Center  

E-print Network

Arkansas Water Resources Center RECONNAISSANCE SURVEY OF NITRATE CONCENTRATIONS IN GROUND WATER caused concern regarding nitrate contamination of the ground water. In the study area of Pike and Howard water nitrate. In response to these concerns, a study of n1trate concentrations in rural water wells

Soerens, Thomas

388

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.

389

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.

390

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,

391

Water treatment method  

Microsoft Academic Search

This paper describes a method for treating water removed from the ground to reduce the content of noxious sulfur-containing impurities therein before the water is supplied to an associated water system. It comprises: the steps of spraying the water to be treated in the upper portion of a closed standpipe which has an inlet for the water to be treated

Siebert

1991-01-01

392

Water security for Kuwait  

Microsoft Academic Search

Water security depends on the availability of enough water to meet the demand of all consumption sectors at all times. These conditions are hardly met in water rich countries, as the hydrological cycle is not fully reliable. In arid countries, such as Kuwait, where there is no enough natural fresh water, water security is generally based on enough storage capacity

Abdulhadi Al-Otaibi; Mahmoud Abdel-Jawad

2007-01-01

393

TiO2/palygorskite composite nanocrystalline films prepared by surfactant templating route: synergistic effect to the photocatalytic degradation of an azo-dye in water.  

PubMed

Microfibrous palygorskite clay mineral and nanocrystalline TiO(2) are incorporating in the preparation of nanocomposite films on glass substrates via sol-gel route at 500°C. The synthesis involves a simple chemical method employing nonionic surfactant molecule as pore directing agent along with the acetic acid-based sol-gel route without direct addition of water molecules. Drying and thermal treatment of composite films lead to the elimination of organic material while ensure the formation of TiO(2) nanoparticles homogeneously distributed on the surface of the palygorskite microfibers. TiO(2) nanocomposite films without cracks consisted of small crystallites in size (12-16 nm) and anatase crystal phase was found to cover palygorskite microfibers. The composite films were characterized by microscopy techniques, UV-vis, IR spectroscopy, and porosimetry methods in order to examine their structural properties. Palygorskite/TiO(2) composite films with variable quantities of palygorskite (0-2 w/w ratio) were tested as new photocatalysts in the photo-discoloration of Basic Blue 41 azo-dye in water. These nanocomposite films proved to be very promising photocatalysts and highly effective to dye's discoloration in spite of the small amount of immobilized palygorskite/TiO(2) catalyst onto glass substrates. 3:2 palygorskite/TiO(2) weight ratio was finally the most efficient photocatalyst while reproducible discoloration results of the dye were obtained after three cycles with same catalyst. It was also found that palygorskite showed a positive synergistic effect to the TiO(2) photocatalysis. PMID:22177018

Stathatos, E; Papoulis, D; Aggelopoulos, C A; Panagiotaras, D; Nikolopoulou, A

2012-04-15

394

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

395

Investigating Water Problems. A Water Analysis Manual.  

ERIC Educational Resources Information Center

This booklet has been prepared expressly for teachers and students who are interested in investigating the quality of water supplies. The intent is to provide technical support and background information concerning water quality factors and to give basic information on field and laboratory water testing techniques. It is assumed that the reader is…

Renn, Charles E.

396

Cleaner, Safer Water through Water Safety Plans  

E-print Network

(NCEH) Global Water, Sanitation, and Hygiene Team's Water Safety Plan Assistance 1.5 million deaths occur globally every year due to a lack of clean water, inadequate sanitation, and improper hygiene (1, Sanitation, and Hygiene team provides WSP technical assistance throughout Latin America and the Caribbean

397

WATER RECLAMATION AND AUTOMATED WATER QUALITY MONITORING  

EPA Science Inventory

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

398

The Science of Water  

NSDL National Science Digital Library

A series of inquiry lessons and resources that help students understand the physical properties of water, that living organisms are dependent on water, and how water affects their health and that of the planet.

Baylor College of Medicine (Baylor College of Medicine Human Genome Sequencing Center)

2010-01-01

399

Water in the City  

NSDL National Science Digital Library

Water in the City is part of the Franklin Institute Science Museum's Science in the City Web site. The activity is described as a way to investigate the most precious natural resource in cities. The resources accumulated and presented on the site are held within several areas that include Water Basics, Water Science, Philadelphia Water Ways, Worldwide Water Ways, and References and Activities. The water basics page, for example, contains a glossary of water terminology; water trivia; and information on water myths and realities, dams, water power, conserving water, and keeping water clean. Although most resources are from outside sources, the site does a good job of explaining the concepts and providing kids with a single spot to explore other sites with information on this specific subject.

400

LAND & WATER CONSERVATION PROGRAM  

E-print Network

LAND & WATER CONSERVATION PROGRAM ________________________________________________________________________ Preparing a Conservation Plan INTRODUCTION Conservation of land, water and other natural features. Examples of goals might include protecting the water resources of a town, maintaining or improving local

New Hampshire, University of

401

water transport land runoff  

E-print Network

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

Torgersen, Christian

402

Bottled Water and Fluoride  

MedlinePLUS

... 110. The FDA standards of quality state that domestic bottled water with no added fluoride may contain ... the location where the bottled water is sold. Domestic bottled water with added fluoride can contain between ...

403

Reduction of Water Consumption  

E-print Network

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

Adler, J.

404

EXPLANATION Water withdrawals,  

E-print Network

-water livestock withdrawals Groundwater livestock withdrawals TOTALWITHDRAWALS,IN MILLIONGALLONSPERDAY WEST EAST 0 in the United States in 2005 - Livestock USGS Water-Science School -- http://ga.water.usgs

405

Lawn Water Management  

E-print Network

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

McAfee, James

2006-06-26

406

Aging Water Infrastructure  

EPA Science Inventory

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

407

It's Your Drinking Water  

MedlinePLUS

... drinking water program. Many are available via the Internet. Call the Safe Drinking Water Hotline at (800) ... been meeting drinking water safety standards, on the Internet at: www.epa.gov/safewater/dwinfo.htm DETERMINING ...

408

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

409

About Body Water  

MedlinePLUS

... kidneys are functioning normally, the body can handle wide variations in fluid intake. The body obtains water ... such as sodium and potassium, are dissolved in the water in the body. Water balance and electrolyte balance ( ...

410

Drinking Water Problems: Radionuclides  

E-print Network

Radionuclides in drinking water can cause serious health problems for people. This publication explains what the sources of radionuclides in water are, where high levels have been found in Texas, how they affect health and how to treat water...

Lesikar, Bruce J.; Melton, Rebecca; Hare, Michael; Hopkins, Janie; Dozier, Monty

2006-08-04

411

OFFICE OF WATER DOCKET  

EPA Science Inventory

Resource Purpose: The Office of Water (OW) develops regulations and standards for contaminants in the Nation's waters. Section 101(e) of the Clean Water Act requires that "public participation in the development or revision of any regulations, standard, effluent limitation,...

412

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

2011-07-13

413

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

NSDL National Science Digital Library

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

1999-01-01

414

Surface Water Quality Standards  

E-print Network

of the water quali- ty standards, the overall process is expected to contin- ue into 2009.? For some, Texas? standards for contact recreation are not appropriate for many water bodies on the impaired list. Aaron Wendt, Texas State Soil and Water... of the water quali- ty standards, the overall process is expected to contin- ue into 2009.? For some, Texas? standards for contact recreation are not appropriate for many water bodies on the impaired list. Aaron Wendt, Texas State Soil and Water...

Wythe, Kathy

2007-01-01

415

Technology in water conservation  

E-print Network

2 tx H2O Summer 2013 Column by Dr. Calvin Finch, Water Conservation and Technology Center director WAT E R CONSERVATION & TECHNOLOGY CENTER Securing Our Water Future It is not unusual for individuals to describe water conservation as a... through water conservation, introduction of new technology does not automati- cally result in water savings. #27;e new evapotrans- piration-based irrigation controllers illustrate the point. A lawn?s need for water is dependent on the weather...

Finch, Dr. Calvin

2013-01-01

416

Industrial Water Use  

NSDL National Science Digital Library

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

2002-10-10

417

Water Resources Research Center  

NSDL National Science Digital Library

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

418

Ground water resource assessment  

SciTech Connect

Table of Contents: Introduction to Ground Water Resource Assessment; Components of a Ground Water Resource Assessment; Approaches to Assessing Aquifer Sensitivity and Ground Water Vulnerability; Comprehensive State Ground Water Protection Program Priority-Setting Characteristics to be Addressed in Ground Water Resource Assessments; Case Studies on the Development and Use of Ground Water Resource Assessments at the State, Local, and Federal Level; Sources of Hydrogeological Information; and Glossary.

Not Available

1993-10-01

419

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.

420

Water Cycle Webquest  

NSDL National Science Digital Library

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

421

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

422

Mission Geography: Water, Water Almost Everywhere  

NSDL National Science Digital Library

Mission Geography uses existing NASA data and images where possible to engage students in active, hands-on inquiry, modeling the scientific method and developing students' understanding of environment-society relations and Earth science. In this module, students compare the amount of land and water on Earth; consider craters as evidence of a lack of water on other planets; define and locate water bodies found on Earth; and identify changes that occur in these water bodies. The module contains four investigations in which students compare the amounts of land and water on Earth, learn that the presence of craters indicate a dry planet, study and compare water bodies, and explore how water bodies respond to changes in weather and climate. Each investigation is complete with overview, a list of materials and supplies, content preview, classroom procedures, worksheets, background, and evaluation.

423

Surface Water Development in Texas.  

E-print Network

.................................. 14 Counties and Cities ............................... 14 Water Districts .................................... 14 State Water Agencies ................................. 15 Board of Water Engineers ......................... 15 Water Rights... Commission ......................... 15 Water Development Board ......................... 15 Federal Water Agencies ............................... 18 U.S. Army Corps of Engineers ...................... 18 Bureau of Reclamation...

McNeely, John G.; Lacewell, Ronald D.

1977-01-01

424

Kunming experiences water shortage  

SciTech Connect

This article examines a Chinese city's measures to plan the water supply and conserve water, and to ensure a regular supply of water to drink and use in production. The Kunming city government called an emergency mobilization meeting on water conservation. Kunming has suffered from a severe lack of rainfall over the past 2 years. In order to overcome the present water shortage, it was decided to publicize the importance of planning the water supply and water conservation; to set limits on the amount of water used and to crack down on large consumers of water; and to make further rational and scientific uses of water. The Kunming government has proposed saving 20% of the water now being consumed.

Sun Chaozhen

1983-07-17

425

2010 Water & Aqueous Solutions  

SciTech Connect

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

Dor Ben-Amotz

2010-08-13

426

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

427

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

Microsoft Academic Search

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

L. Glasser

2004-01-01

428

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

SciTech Connect

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

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

2012-10-08

429

Water treatment method  

SciTech Connect

This paper describes a method for treating water removed from the ground to reduce the content of noxious sulfur-containing impurities therein before the water is supplied to an associated water system. It comprises: the steps of spraying the water to be treated in the upper portion of a closed standpipe which has an inlet for the water to be treated and an outlet through which water can flow to the associated water system, the inlet and the outlet of the standpipe being so positioned that air which becomes disassociated from water can collect in the upper portion of the standpipe, controlling the spraying of water in the upper portion of the closed standpipe to maintain a superatmospheric therein to pressurize the associated water system, entraining air with the water before it is sprayed in the standpipe. The last named step being carried out in a vessel in which the ground water is sprayed upwardly, maintaining the water level in the standpipe that is required to enable the flow of water therefrom to the associated water system, containing the ground water, before it is delivered to the associated water system, with a catalyst for the oxidation of sulfur and sulfur-containing moieties to sulfate anions, and controlling the time of contact between the ground water and the catalyst, the amount of air entrained with the water sprayed in the vessel and the amount of air entrained with the water sprayed in the standpipe so that entrained air separates from the water and forms an air pocket inside the standpipe and there is a substantially complete oxidation of sulfur and sulfur-containing moieties to sulfate anions.

Siebert, G.H.

1991-02-12

430

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.

431

Water Resources Milind Sohoni  

E-print Network

soil conditions and on all crops. () January 13, 2010 8 / 14 #12;FIM vs. DIM source: A. NarayanamoorthyTD 603 Water Resources Milind Sohoni www.cse.iitb.ac.in/sohoni/ Lecture 9: Water in Agriculture () January 13, 2010 1 / 14 #12;Water in Agriculture Historically: Biggest consumer of water, in developed

Sohoni, Milind

432

Water Resources Milind Sohoni  

E-print Network

TD 603 Water Resources Milind Sohoni www.cse.iitb.ac.in/sohoni/ Lecture 5: Aquifer () August 16 above and below the ground, which affect the water balance. surface features affect infiltration parameters related to water: Porosity, specific yield n, Sy : the maximum volume fraction of water

Sohoni, Milind

433

Water Resources Milind Sohoni  

E-print Network

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

Sohoni, Milind

434

Water Resources Milind Sohoni  

E-print Network

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

Sohoni, Milind

435

Water Resources Milind Sohoni  

E-print Network

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

Sohoni, Milind

436

Water Waves Roger Grimshaw  

E-print Network

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

437

Lifting China's Water Spell.  

PubMed

China is a country with significant but unevenly distributed water resources. The water stressed North stays in contrast to the water abundant and polluted South defining China's current water environment. In this paper we use the latest available data sets and adopt structural decomposition analysis for the years 1992 to 2007 to investigate the driving forces behind the emerging water crisis in China. We employ four water indicators in China, that is, freshwater consumption, discharge of COD (chemical oxygen demand) in effluent water, cumulative COD and dilution water requirements for cumulative pollution, to investigate the driving forces behind the emerging crisis. The paper finds water intensity improvements can effectively offset annual freshwater consumption and COD discharge driven by per capita GDP growth, but that it had failed to eliminate cumulative pollution in water bodies. Between 1992 and 2007, 225 million tonnes of COD accumulated in Chinese water bodies, which would require 3.2-8.5 trillion m(3) freshwater, depending on the water quality of the recipient water bodies to dilute pollution to a minimum reusable standard. Cumulative water pollution is a key driver to pollution induced water scarcity across China. In addition, urban household consumption, export of goods and services, and infrastructure investment are the main factors contributing to accumulated water pollution since 2000. PMID:25226569

Guan, Dabo; Hubacek, Klaus; Tillotson, Martin; Zhao, Hongyan; Liu, Weidong; Liu, Zhu; Liang, Sai

2014-10-01

438

Water treatment residuals  

Microsoft Academic Search

Solutions to an environmental problem often create other environmental problems. That surely is the case in the water supply field. By providing new or expanded water treatment systems to comply with the maximum contaminant levels and treatment mandates of the Safe Drinking Water Act, water purveyors are generating large volumes of residuals that must be managed, ultimately disposed of, or

Billings

1994-01-01

439

Can Water Mean Health?  

ERIC Educational Resources Information Center

This issue of UNICEF News explores the theme of connections between water and health in developing countries. The introductory article discusses prospects for improving health through water projects during the International Drinking Water Supply and Sanitation Decade (1981-90). Subsequent articles focus on (1) effects of a piped water supply on…

Black, Maggie, Ed.

1983-01-01

440

Global Water Distribution  

NSDL National Science Digital Library

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

Foundation, Wgbh E.

2005-12-17

441

EXPLANATION Water withdrawals,  

E-print Network

withdrawals Surface-water withdrawals Groundwater withdrawals 0 20,000 40,000 60,000 Haw aiiAlaskaOregon W,IN MILLIONGALLONSPERDAY WEST EAST Total, surface-water, and groundwater withdrawals, 2005. EstimatedUseofWaterintheUnitedStatesin2005 USGS Water-Science School -- http://ga.water.usgs.gov/edu/ Source: Kenny, J.F., Barber, N

442

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

443

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

444

Alabama Water Use, 2005  

USGS Publications Warehouse

Water is one of Alabama's most precious natural resources. It is a vital component of human existence and essential to the overall quality of life. Wise stewardship of this valuable resource depends on a continuing assessment of water availability and water use. Population growth in many parts of the State has resulted in increased competition for available water resources. This competition includes offstream uses, such as residential, agricultural, and industrial, and instream uses for maintenance of species habitat and diversity, navigation, power generation, recreation, and water quality. Accurate water-use information is required for sound management decisions within this competitive framework and is necessary for a more comprehensive understanding of the link between water use, water supply, and overall water availability. A study of water use during 2005 was conducted by the U.S. Geological Survey (USGS), in cooperation with the Alabama Department of Economic and Community Affairs, Office of Water Resources, Water Management Branch (ADECA-OWR), to provide water-use data for local and State water managers. The results of the study about the amount of water used, how it was used, and where it was used in Alabama have been published in 'Estimated use of water in Alabama in 2005' by Hutson and others, 2009, and is accessible on the Web at http://pubs.usgs.gov/sir/2009/5163 and available upon request as a CD-ROM through USGS and ADECA-OWR.

Hutson, Susan S.; Littlepage, Thomas M.; Harper, Michael J.; Tinney, James O.

2009-01-01

445

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

446

Kunming experiences water shortage  

Microsoft Academic Search

This article examines a Chinese city's measures to plan the water supply and conserve water, and to ensure a regular supply of water to drink and use in production. The Kunming city government called an emergency mobilization meeting on water conservation. Kunming has suffered from a severe lack of rainfall over the past 2 years. In order to overcome the

Sun Chaozhen

1983-01-01

447

Potable water supply  

NASA Technical Reports Server (NTRS)

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

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

1975-01-01

448

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

449

Water Resources News  

NSDL National Science Digital Library

The Water Resources division of the US Geological Service provides this water news resource, tracking current water-related events and recent publications from across the US. Recent news items include: flooding in Texas, the impacts of Hurricane Bonnie, the release of a USGS report on water use in the US, and stream-flow data from Puerto Rico, to name a few.

450

The Water Cycle  

NSDL National Science Digital Library

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

451

Arkansas Water Resources Center  

E-print Network

Arkansas Water Resources Center ATRAZINE DEGRADATION, SORPTION AND BIOCONCENTRATION IN WATER degradation, sorption, and bioconcentration in water- The results indicated that sediments with lower p SYSTEMS PREPARED BY: Duane C. Wolf And Ramon L. Jackson MSC-83B August 1982 ARKANSAS WATER RESOURCES

Soerens, Thomas

452

Domestic wash water reclamation  

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

453

Potable water taste enhancement  

NASA Technical Reports Server (NTRS)

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

1974-01-01

454

Arkansas Water Resources Center  

E-print Network

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

Soerens, Thomas

455

Irrigation Water Quality  

E-print Network

Irrigation water quality is determined by the total amounts of salts and the types of salts the water contains. In this publication you'll learn why well water can be salty, what problems salty water can cause, what tests should be done...

McFarland, Mark L.; Lemon, Robert G.; Stichler, Charles

2002-04-11

456

Arkansas Water Resources Center  

E-print Network

Arkansas Water Resources Center NITRATE CONCENTRATIONS OF GROUND WATER BENTON COUNTY, ARKANSAS potential sources of contaminants, especially nitrate. A suJrvey of ground water nitrate conc4entrations of Arkansas Fayetteville, Arkansas 72701 And Kenneth F. Steele, Principal Investigator Arkansas Water

Soerens, Thomas

457

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

458

WATER QUALITY CRITERIA DOCUMENTS  

EPA Science Inventory

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

459

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

460

Reflections on Water (and \\  

Microsoft Academic Search

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

Barbara C. Malt

461

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