Sample records for water electrocatalysis photocatalysis

  1. Water Purification by Photocatalysis on Semiconductors

    Microsoft Academic Search

    A. Sobczy?ski; A. Dobosz

    This paper describes the basics of photocatalysis on semiconductors, mainly on TiO2 and the application of photocatalytic processes to water purification from organic matter. The second chapter is devoted to metal cocatalysts introduced in order to improve the photocatalytic action of titania. Finally, a short review of more interesting practical applications of the processes is presented.

  2. WATER TREATMENT BY HETEROGENEOUS PHOTOCATALYSIS AN OVERVIEW1

    Microsoft Academic Search

    Radwan A. Al-Rasheed

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

  3. Developments in solar photocatalysis for water purification.

    PubMed

    Vidal, A

    1998-05-01

    Photocatalytic processes in the presence of titanium dioxide provide an interesting route to destroy hazardous organic contaminants, being operational in the UV-A domain with a potential use of solar radiation. In this paper, some specific contaminant classes of interest such as ethylbenzene, gamma-lindane and EPTC have been tested at laboratory scale and in the field to determine the feasibility of the photocatalytic oxidation of organic contaminants in water. Our preliminary results at laboratory scale with these chemicals have provided a better understanding of the photocatalytic process which seems to be efficient and not selective. The application of these processes in removal of gamma-lindane from water operating in a parabolic trough concentrator has demonstrated to be effective, being possible to reduce 99.9% of gamma-lindane levels in water in acceptable times. PMID:9570109

  4. A review of heterogeneous photocatalysis for water and surface disinfection.

    PubMed

    Byrne, John Anthony; Dunlop, Patrick Stuart Morris; Hamilton, Jeremy William John; Fernández-Ibáñez, Pilar; Polo-López, Inmaculada; Sharma, Preetam Kumar; Vennard, Ashlene Sarah Margaret

    2015-01-01

    Photo-excitation of certain semiconductors can lead to the production of reactive oxygen species that can inactivate microorganisms. The mechanisms involved are reviewed, along with two important applications. The first is the use of photocatalysis to enhance the solar disinfection of water. It is estimated that 750 million people do not have accessed to an improved source for drinking and many more rely on sources that are not safe. If one can utilize photocatalysis to enhance the solar disinfection of water and provide an inexpensive, simple method of water disinfection, then it could help reduce the risk of waterborne disease. The second application is the use of photocatalytic coatings to combat healthcare associated infections. Two challenges are considered, i.e., the use of photocatalytic coatings to give "self-disinfecting" surfaces to reduce the risk of transmission of infection via environmental surfaces, and the use of photocatalytic coatings for the decontamination and disinfection of medical devices. In the final section, the development of novel photocatalytic materials for use in disinfection applications is reviewed, taking account of materials, developed for other photocatalytic applications, but which may be transferable for disinfection purposes. PMID:25830789

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

    PubMed

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

    2014-12-01

    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 (<5 kW h m(-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 (80-160 kW h m(-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

  6. 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 ...

  7. Granular activated carbon (GAC) adsorption-photocatalysis hybrid system in the removal of herbicide from water

    Microsoft Academic Search

    N. Areerachakul; S. Vigneswaran; H. H. Ngo; J. Kandasamy

    2007-01-01

    The performance of the granular activated carbon (GAC) fixed bed adsorption, the continuous photocatalysis systems and a combination of the two were studied to evaluate their capabilities in removing the herbicide of metsulfuron-methyl (MM) from waste water. Columns packed with GAC at different bed depths were operated at different filtration rates over a period of several weeks. Removal of MM

  8. Heterogeneous photocatalysis of moxifloxacin in water: chemical transformation and ecotoxicity.

    PubMed

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

    2015-01-01

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

  9. New Photocatalysis for Effective Degradation of Organic Pollutants in Water

    Microsoft Academic Search

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

    2009-01-01

    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

  10. Photo and electro-catalysis for solar disinfection of Escherichia coli-contaminated water using Ag–TiO2\\/graphite

    Microsoft Academic Search

    Fitria Rahmawati; Triana Kusumaningsih; Aris Hastuti

    2011-01-01

    A titanium dioxide film on a graphite substrate was synthesized by chemical bath deposition from TiCl4 as precursor and with the surfactant cetyl trimethyl ammonium bromide as a linking and assembling agent. Silver was loaded on the TiO2 film by electrodeposition at 0.025?A. Water contaminated with Escherichia coli was disinfected under sunlight irradiation by photolysis (Lys), photocatalysis (PC), photoelectrocatalysis (PEC),

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

    PubMed

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

    2013-07-23

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

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

    Microsoft Academic Search

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

    2011-01-01

    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,

  13. Water-splitting electrocatalysis in acid conditions using ruthenate-iridate pyrochlores.

    PubMed

    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

    The pyrochlore solid solution (Na(0.33)Ce(0.67))2(Ir(1-x)Ru(x))2O7 (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 L(III) 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

  14. Water-Splitting Electrocatalysis in Acid Conditions Using Ruthenate-Iridate Pyrochlores**

    PubMed Central

    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

    2014-01-01

    The pyrochlore solid solution (Na0.33Ce0.67)2(Ir1?xRux)2O7 (0?x?1), containing B-site RuIV and IrIV 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

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

    NASA Astrophysics Data System (ADS)

    Prakash, Jai; Tryk, Donald; Yeager, Ernest

    1989-12-01

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

  16. Silver and gold icosahedra: one-pot water-based synthesis and their superior performance in the electrocatalysis for oxygen reduction reactions in alkaline media.

    PubMed

    Kuai, Long; Geng, Baoyou; Wang, Shaozhen; Zhao, Yanyan; Luo, Yinchan; Jiang, Han

    2011-03-14

    Much effort has gone into generating polyhedral noble metal nanostructures because of their superior electrocatalytic activities for fuel cells. Herein, we report uniform, high-yield icosahedral silver and gold nanoparticles by using a facile one-pot, seedless, water-based approach that incorporates polyvinyl pyrrolidone and ammonia. Electrocatalysis of the oxygen-reduction reaction was carried out in alkaline media to evaluate the performance of the icosahedral nanoparticles. They showed excellent stability and much higher electrocatalytic activity than the spherelike nanoparticles; they display a positive shift in reduction peak potential for O(2) of 0.14 and 0.05 V, while the reduction peak currents of the silver and gold icosahedra are 1.5- and 1.6-fold, respectively, better than the spherelike nanoparticles. More importantly, the icosahedral nanoparticles display electrocatalytic activities comparable with commercial Pt/C electrocatalysts. The facile preparation of icosahedral silver and gold nanoparticles and their superior performance in the oxygen reduction reaction render them attractive replacements for Pt as cathode electrocatalysts in alkaline fuel cells. PMID:21344521

  17. Water Oxidation on Pure and Doped Hematite (0001) Surfaces: Prediction of Co and Ni as Effective Dopants for Electrocatalysis

    E-print Network

    Carter, Emily A.

    be converted into chemical energy by splitting water into hydrogen and oxygen molecules. Hematite (-Fe2O3 which can be used as a fuel itself or as a feedstock to produce liquid fuels. Water splitting requires chemical energy. The water splitting reaction, H2O H2 + O2 (E0 = -1.23 V), produces H2 energy carriers,1

  18. Titanium dioxide photocatalysis

    Microsoft Academic Search

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

    2000-01-01

    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

  19. Nanomaterials for Sensing and Electrocatalysis

    Microsoft Academic Search

    Jinghong Li; Yuehe Lin

    2009-01-01

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

  20. Electrocatalysis at metal nanomaterials

    NASA Astrophysics Data System (ADS)

    Dai, Lin

    Direct liquid fuel cells, such as direct methanol fuel cells and direct formic acid fuel cells, have attracted much attention in the past decades due to the need of clean and efficient power sources. One of the most critical issues in the development of highly efficient fuel cells is to increase the rates of fuel-cell reactions as a commercial product. As a result, the topic of electrocatalysis plays a significant role in the investigations of fuel cell reactions. For methanol oxidation, platinum based nanomaterials are the most important catalysts. For formic acid oxidation, both platinum and palladium based nanomaterials are widely employed as the catalysts. Recently, shape-control of the nanoparticles has become an imperative task due to the fact that most of the reactions in fuel cells are sensitive to the surface structure of the catalysts. Though numerous studies have been conducted in past to elucidate the catalytic activity on the nanomaterials with different shapes, the results are inconclusive. Herein, systematic comparison of catalytic activity toward methanol and formic acid oxidation on shape-controlled cubic platinum-based alloy nanoparticles with different alloy element are reported in this dissertation. Methanol and formic acid oxidation reactions on spherical and cubic Pt-Cu nanoparticles are also studied. Cu-Pd nanoparticles are synthesized through galvanic redox reactions to provide significantly higher and much more stable formic acid oxidation activities. Interparticle distance effect is investigated on two dimensional nanoparticle array electrodes with controlled particle size, which is ideal model system for exploring the interparticle distance effects on the voltammetric behavior and reaction mechanisms.

  1. Hydrogen production by advanced proton exchange membrane (PEM) water electrolysers—Reduced energy consumption by improved electrocatalysis

    Microsoft Academic Search

    A. Marshall; B. Børresen; G. Hagen; M. Tsypkin; R. Tunold

    2007-01-01

    Proton exchange membrane (PEM) water electrolysis systems offers several advantages over traditional technologies including greater energy efficiency, higher production rates, and more compact design. Normally in these systems, the anode has the largest overpotential at typical operating current densities. By development of the electrocatalytic material used for the oxygen evolving electrode, great improvements in efficiency can be made. We find

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

    NASA Astrophysics Data System (ADS)

    Suo, Zhirong; Dong, Xiaonan; Liu, Hui

    2013-10-01

    A new microwave-assisted hydrothermal synthetic route based on the self-assembly and subsequently controlled thermal decomposition process is proposed to fabricate nickel oxide colloidal nanocrystal aggregated microspheres (CNAMs) with mesoporous structure. XRD, EDS, SEM, TEM. FTIR, and N2 adsorption and desorption isotherm techniques are employed for morphology and structure characterizations. The as-prepared nickel oxide CNAMs, which has a high surface area (234 m2/g) with narrow pore distribution at around 3.25 nm, are composed of numerous hexagonal mesoporous nanocrystals of approximately 50-60 nm in size, and present a single-crystal-like characteristic. The experimental results also demonstrated that the CNAMs showed outstanding performance in electrochemistry, photocatalysis and waste water treatment due to their special hierarchical and mesoporous structure, presenting the promising candidate for catalysis and catalysis support materials.

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

    PubMed

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

    2005-01-01

    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

  4. A hybridized photocatalysis–microfiltration system with iron oxide-coated membranes for the removal of natural organic matter in water treatment: Effects of iron oxide layers and colloids

    Microsoft Academic Search

    Ping Yao; Kwang-Ho Choo; Moon-Hyeon Kim

    2009-01-01

    A photocatalysis\\/microfiltration (MF) hybrid system, with the coating of a membrane using iron oxide particles (IOPs), was investigated with respect to natural organic matter (NOM) removal and membrane permeability during the treatment of various surface waters. A comparison of the performance between bare (uncoated) and IOP-coated membranes employed for the photocatalytic hybrid system was made. Due to the additional adsorption of

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

    SciTech Connect

    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

    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.

  6. DNA sensing by electrocatalysis with hemoglobin

    PubMed Central

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

    2012-01-01

    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

  7. Multifunctional Metal-Organic Frameworks for Photocatalysis.

    PubMed

    Wang, Sibo; Wang, Xinchen

    2015-07-01

    Metal-organic frameworks (MOFs) have attracted significant research attention in diverse areas due to their unique physical and chemical characteristics that allow their innovative application in various research fields. Recently, the application of MOFs in heterogeneous photocatalysis for water splitting, CO2 reduction, and organic transformation have emerged, aiming at providing alternative solutions to address the world-wide energy and environmental problems by taking advantage of the unique porous structure together with ample physicochemical properties of the metal centers and organic ligands in MOFs. In this review, the latest progress in MOF-involved solar-to-chemical energy conversion reactions are summarized according to their different roles in the photoredox chemical systems, e.g., photocatalysts, co-catalysts, and hosts. The achieved progress and existing problems are evaluated and proposed, and the opportunities and challenges of MOFs and their related materials for their advanced development in photocatalysis are discussed and anticipated. PMID:25917413

  8. A hybridized photocatalysis-microfiltration system with iron oxide-coated membranes for the removal of natural organic matter in water treatment: effects of iron oxide layers and colloids.

    PubMed

    Yao, Ping; Choo, Kwang-Ho; Kim, Moon-Hyeon

    2009-09-01

    A photocatalysis/microfiltration (MF) hybrid system, with the coating of a membrane using iron oxide particles (IOPs), was investigated with respect to natural organic matter (NOM) removal and membrane permeability during the treatment of various surface waters. A comparison of the performance between bare (uncoated) and IOP-coated membranes employed for the photocatalytic hybrid system was made. Due to the additional adsorption of NOM onto IOPs on the membrane surface, the IOP-coated membrane system always achieved greater DOC removal efficiencies during photocatalysis/MF. Particularly, the influence of colloidal particles that were present in different water sources with respect to membrane fouling was explored. Colloidal fouling occurred to both bare and IOP-coated membranes, but the interaction of colloids with IOP coating layers was in close association with the characteristics of colloids, such as size distribution, resulting in opposing fouling behaviors with varying water sources. The IOP-coated membrane was able to control fouling properly when a relatively large size of colloidal particles existed in raw water, but not for the case of small colloids. The IOP coat layer may become denser as small colloids penetrate into it, therefore leading to further fouling. The analysis of the hydraulic filtration resistances revealed that such fouling was virtually reversible in being removed by backwashing processes. Scanning electron microscopic observations, however, visualized the existence of several foulants remaining at the membrane surface after backwashing when feed water, containing a relatively large portion of small-sized colloids, was supplied. PMID:19576613

  9. Plasmon-enhanced UV photocatalysis

    SciTech Connect

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

    2014-02-10

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

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

    Microsoft Academic Search

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

    2010-01-01

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

  11. Role of Nanoparticles in Photocatalysis

    Microsoft Academic Search

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

    1999-01-01

    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

  12. Structure sensitivity and nanoscale effects in electrocatalysis

    NASA Astrophysics Data System (ADS)

    Koper, Marc T. M.

    2011-05-01

    This review discusses the role of the detailed nanoscale structure of catalytic surfaces on the activity of various electrocatalytic reactions of importance for fuel cells, hydrogen production, and other environmentally important catalytic reactions, such as carbon monoxide oxidation, methanol and ethanol oxidation, ammonia oxidation, nitric oxide reduction, hydrogen evolution, and oxygen reduction. Specifically, results and insights obtained from surface-science single-crystal-based model experiments are linked to experiments on well-defined shape-controlled nanoparticles. A classification of structure sensitive effects in electrocatalysis is suggested, based both on empirical grounds and on quantum-chemical viz. thermochemical considerations. The mutual relation between the two classification schemes is also discussed. The review underscores the relevance of single-crystal modeling of nanoscale effects in catalysis, and points to the special role of two kinds of active sites for electrocatalysis on nanoparticulate surfaces: (i) steps and defects in (111) terraces or facets, and (ii) long-range (100) terraces or facets.

  13. Fuel cell applied research: Electrocatalysis and materials

    NASA Astrophysics Data System (ADS)

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

    1980-03-01

    The effect of underpotential deposited metal layers on the electrocatalysis of fuel cell reactions is studied. The potential for developing organic compound/air fuel cells using underpotential deposited Pb adatoms to enhance the electrocatalysis of the fuel electrode is explored. The effects of adsorbed layers of Pb, Tl and Bi on formic acid and methanol oxidation on platinum in 85 percent H3PO4 were investigated. The effect of crystal orientation on formic acid oxidation on platinum in 1 M CHlO2 was investigated. The kinetics of the oxygen reduction and evolution reactions at the electrode (metal or oxide) solid electrolyte (yttria stabilized zirconia) interface were investigated using ac and dc techniques.

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

    NASA Astrophysics Data System (ADS)

    Selloni, Annabella

    2011-03-01

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

  15. Metal-organic frameworks for artificial photosynthesis and photocatalysis.

    PubMed

    Zhang, Teng; Lin, Wenbin

    2014-08-21

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

  16. Structure sensitivity and nanoscale effects in electrocatalysis.

    PubMed

    Koper, Marc T M

    2011-05-01

    This review discusses the role of the detailed nanoscale structure of catalytic surfaces on the activity of various electrocatalytic reactions of importance for fuel cells, hydrogen production, and other environmentally important catalytic reactions, such as carbon monoxide oxidation, methanol and ethanol oxidation, ammonia oxidation, nitric oxide reduction, hydrogen evolution, and oxygen reduction. Specifically, results and insights obtained from surface-science single-crystal-based model experiments are linked to experiments on well-defined shape-controlled nanoparticles. A classification of structure sensitive effects in electrocatalysis is suggested, based both on empirical grounds and on quantum-chemical viz. thermochemical considerations. The mutual relation between the two classification schemes is also discussed. The review underscores the relevance of single-crystal modeling of nanoscale effects in catalysis, and points to the special role of two kinds of active sites for electrocatalysis on nanoparticulate surfaces: (i) steps and defects in (111) terraces or facets, and (ii) long-range (100) terraces or facets. PMID:21399781

  17. Reductive photocatalysis and smart inks.

    PubMed

    Mills, Andrew; Wells, Nathan

    2015-05-21

    Semiconductor-sensitised photocatalysis is a well-established and growing area of research, innovation and commercialisation; the latter being mostly limited to the use of TiO2 as the semiconductor. Most of the work on semiconductor photocatalytic systems uses oxygen as the electron acceptor and explores a wide range of electron donors; such systems can be considered to be examples of oxidative photocatalysis, OP. OP underpins most current examples of commercial self-cleaning materials, such as: glass, tiles, concrete, paint and fabrics. OP, and its myriad of applications, have been reviewed extensively over the years both in this journal and elsewhere. However, the ability of TiO2, and other semiconductor sensitisers, to promote reductive photocatalysis, RP, especially of dyes, is significant and, although less well-known, is of growing importance. In such systems, the source of the electrons is some easily oxidised species, such as glycerol. One recent, significant example of a RP process is with respect to photocatalyst activity indicator inks. paiis, which provide a measure of the activity of a photocatalytic film under test via the rate of change of colour of the dye in the ink coating due to irreversible RP. In contrast, by incorporating the semiconductor sensitiser in the ink, rather than outside it, it is possible to create an effective UV dosimeter, based on RP, which can be used as a sun-burn warning indicator. In the above examples the dye is reduced irreversibly, but when the photocatalyst in an ink is used to reversibly photoreduce a dye, a novel, colourimetric oxygen-sensitive indicator ink can be created, which has commercial potential in the food packaging industry. Finally, if no dye is present in the ink, and the semiconductor photocatalyst-loaded ink film coats an easily reduced substrate, such as a metal oxide film, then it can be used to reduce the latter and so, for example, clean up tarnished steel. The above are examples of smart inks, i.e. inks that are active and provide either dynamic information (such as UV dose or O2 level) or a useful function (such as tarnish removal), and all work via a RP process and are reviewed here. PMID:25773270

  18. TiO 2 photocatalysis and related surface phenomena

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

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

  19. Application of semiconductor photocatalysis for organic synthesis: from photons to the process

    Microsoft Academic Search

    J. T. Leite Pimenta Carneiro

    2010-01-01

    In photocatalysis light drives the reactions. When a semiconductor, such as titania, is exposed to light of a specific wavelength range, several physical processes occur and chemical reactions can take place at its surface in the presence of a reactant. This technology works well for wastewater and air cleaning applications. In these, trace hazardous compounds present in water and air

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

    PubMed

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

    2012-06-15

    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

  1. Microwaves in Photochemistry and Photocatalysis Vladimir Cirkva

    E-print Network

    Cirkva, Vladimir

    563 14 Microwaves in Photochemistry and Photocatalysis Vladim´ir C´irkva 14.1 Introduction Photochemistry is an interdisciplinary field pertaining to all natural sciences and many technical disciplines [1 the number of reaction steps required to synthesize a desired product: photochemistry often achieves what

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

    PubMed

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

    2014-03-01

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

  3. Developments in solar photocatalysis for water purification

    Microsoft Academic Search

    Alfonso Vidal

    1998-01-01

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

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

    PubMed

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

    2014-11-01

    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

  5. Recyclable enzyme mimic of cubic Fe3O4 nanoparticles loaded on graphene oxide-dispersed carbon nanotubes with enhanced peroxidase-like catalysis and electrocatalysis

    SciTech Connect

    Wang, Hua; Li, Shuai; Si, Yanmei; Sun, Zhongzhao; Li, Shuying; Lin, Yuehe

    2014-01-01

    Fe3O4 nanoparticles as nanocatalysts may present peroxidase-like catalysis activities and high electrocatalysis if loaded on conductive carbon nanotube (CNT) supports; however, their catalysis performances in an aqueous system might still be challenged by the poor aqueous dispersion of hydrophobic carbon supports and/or low stability of loaded iron catalysts. In this work, amphiphilic graphene oxide nanosheets were employed as “surfactant” to disperse CNTs to create stable graphene oxide-dispersed CNT (GCNT) supports in water for covalently loading cubic Fe3O4 nanoparticles with improved distribution and binding efficiency. Compared with original Fe3O4 nanos and CNT-loaded Fe3O4 nanocomplex, the prepared GCNT–Fe3O4 nanocomposite could achieve higher aqueous stability and, especially, much stronger peroxidase-like catalysis and electrocatalysis to H2O2, presumably resulting from the synergetic effects of two conductive carbon supports and cubic Fe3O4 nanocatalysts effectively loaded. Colorimetric and direct electrochemical detections of H2O2 and glucose using the GCNT–Fe3O4 nanocomposite were conducted with high detection sensitivities, demonstrating the feasibility of practical sensing applications. Such a magnetically recyclable “enzyme mimic” may circumvent some disadvantages of natural protein enzymes and common inorganic catalysts, featuring the multi-functions of high peroxidase-like catalysis, strong electrocatalysis, magnetic separation/recyclability, environmental stability, and direct H2O2 electrochemistry.

  6. Laser Raman Spectroscopy in studies of corrosion and electrocatalysis

    SciTech Connect

    Melendres, C.A.

    1988-01-01

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

  7. Passivity and electrocatalysis of nanostructured nickel encapsulated in carbon.

    PubMed

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

    2011-07-28

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

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

    E-print Network

    Bonnet, Nicéphore

    2011-01-01

    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 ...

  9. [Photocatalysis characterization of titanium dioxide supported on natural clinoplilolite].

    PubMed

    Fang, Songsheng; Jiang, Yinshan; Wang, Yujie; Bao, Changli; Song, Bo

    2003-07-01

    This paper studied preparing photocatalyst supported on natural clinoplilolite, photocatalysis degrading to methyl orange solution as photocatalysis function test, solar as light resource, explored the synthesize condition and affect factors of its catalysis activity. The capability of catalyst was evaluated by decolor rate and COD removal rate. The samples was described by XRD, IR and specific surface area. Studied result showed that catalyst prepared by combination of tetrabutyl titanate and natural clinoplilolite dryed under 120 degrees C for 6 hours then calcined under 200 degrees C had the best photocatalysis activity. Degrading rate of methyl orange solution increased with the quantity of TiO2/zeolite and additional oxidant H2O2 increasing, but superfluous H2O2 can also restrain the photocatalysis activity of titanium dioxide supported on clinoplilolite. Methyl orange solution had the best degrading rate as pH value between 2 to 5. PMID:14551969

  10. Polar-nonpolar Oxide heterostructures for photocatalysis

    NASA Astrophysics Data System (ADS)

    Guo, Hongli; Zhao, Jin; Saidi, Wissam

    2015-03-01

    The discovery of two-dimensional electron gas (2DEG) at the interface of polar LaAlO3 (LAO) and non-polar SrTiO3 (STO) open the research field of layered oxide heterostructures. In this study, we propose new application of oxide heterostructures for photocatalysis. We take a sandwich-like heterostructure STO/LAO/STO as an example and prove it to be a promising photocatalyst which is active for near-infrared light. Because the sandwiched LAO is polarized and generates a build-in electrostatic field, the valance band and conduction band locates on two opposite STO surfaces. First principles calculations prove that the band gap is reduced and the absorption of near-infrared to visible light is improved distinctly. Simultaneously, the build-in electric field in LAO accelerates the electrons and holes into opposite directions, preventing the recombination, and generates an electron doped surface and a hole doped STO surface, which could be used for H2O reduction and oxidation separately. Our study gives a new perspective into the applications of oxide heterostructures in solar energy conversion.

  11. Dry phase titanium dioxide-mediated photocatalysis: Basis for in situ surface destruction of hazardous chemicals

    SciTech Connect

    Jones, A.P.; Watts, R.J. [Washington State Univ., Pullman, WA (United States). Dept. of Civil and Environmental Engineering

    1997-10-01

    The photocatalytic oxidation of 2,4,6-trichlorophenol (TCP) on the surface of titanium dioxide (TiO{sub 2}) at varying water contents was investigated to provide fundamental data for incorporating photocatalysts into the surface of pavements to promote the destruction of spilled organic chemicals. 2,4,6-Trichlorophenol, spiked onto a thin layer of TiO{sub 2}, was degraded to 20% of its original concentration over 24 h; the release of chloride confirmed the degradation of the parent compound on the surface of the dry TiO{sub 2}. Addition of water ({ge}25% by weight) to the TiO{sub 2} increased the rate of photocatalysis resulting in degradation of TCP to below detectable levels after 20 h. Based on competition studies using the hydroxyl radical scavengers, bicarbonate and 1-octanol, the proposed mechanisms for the dry phase photocatalytic degradation of TCP was oxidation by the valence band hole on the surface of the TiO{sub 2} particle or dehalogenation by superoxide radical anions. Competition studies also confirmed that the more rapid TCP oxidation on wet TiO{sub 2} was primarily the result of generation of hydroxyl radicals through oxidation of water by the valence band hole. The results show that dry phase TiO{sub 2}-mediated photocatalysis may be a potential system for the in situ surface destruction of chemicals that can be oxidized by nonhydroxyl radical mechanisms, such as valence band electron holes and dehalogenation processes.

  12. TiO[sub 2] photocatalysis for the destruction of organics and the reduction of heavy metals

    SciTech Connect

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

    1992-01-01

    This paper describes laboratory work that investigates the applicability of TiO[sub 2] photocatalysis to the treatment of water contaminated with heavy metals and organics. It was found that Ag(l), Cr(VI), Hg(II), and PT(IV) are easily treated while Cd(II), 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. As a result, very efficient photocatalytic decontamination can be realized by applying the technology to water contaminated with the right mixtures of organic compounds and reducible, toxic metals. Data are presented showing how photoefficiencies decrease as light intensity increases in the range of 0 to 20 suns UV. For solar applications, this result suggests that one-sun systems are more efficient than those using concentrated solar radiation. It is also shown that photocatalysis is effective for treating the compound phenylmercuric chloride, suggesting that photocatalysis may find a niche for handling hard-to-treat organometallic complexes.

  13. Energy Conversion and Utilization Technologies Program (ECUT) electrocatalysis research

    NASA Technical Reports Server (NTRS)

    Warren, L. F.

    1984-01-01

    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.

  14. Dr. Piotr Zelenay's Professional Bio Dr. Zelenay's expertise is in polymer electrolyte fuel cells, electrocatalysis, surface

    E-print Network

    Dr. Piotr Zelenay's Professional Bio Dr. Zelenay's expertise is in polymer electrolyte fuel cells associated with Materials Physics and Applications Division at Los Alamos National Laboratory for the last 13 of polymer electrolyte fuel cell science and technology, electrocatalysis, and electrode kinetics. Piotr

  15. Enzyme-Amplified Electrochemical Detection of DNA Using Electrocatalysis of Ferrocenyl-Tethered

    E-print Network

    Kwak, Juhyoun

    We have developed a sandwich-type enzyme-linked DNA sensor as a new electrochemical method to detectArticles Enzyme-Amplified Electrochemical Detection of DNA Using Electrocatalysis of Ferrocenyl-Tethered Dendrimer Eunkyung Kim, Kyuwon Kim, Haesik Yang,*, Youn Tae Kim, and Juhyoun Kwak*, Department of Chemistry

  16. Research progress of perovskite materials in photocatalysis- and photovoltaics-related energy conversion and environmental treatment.

    PubMed

    Wang, Wei; Tadé, Moses O; Shao, Zongping

    2015-08-01

    Meeting the growing global energy demand is one of the important challenges of the 21st century. Currently over 80% of the world's energy requirements are supplied by the combustion of fossil fuels, which promotes global warming and has deleterious effects on our environment. Moreover, fossil fuels are non-renewable energy and will eventually be exhausted due to the high consumption rate. A new type of alternative energy that is clean, renewable and inexpensive is urgently needed. Several candidates are currently available such as hydraulic power, wind force and nuclear power. Solar energy is particularly attractive because it is essentially clean and inexhaustible. A year's worth of sunlight would provide more than 100 times the energy of the world's entire known fossil fuel reserves. Photocatalysis and photovoltaics are two of the most important routes for the utilization of solar energy. However, environmental protection is also critical to realize a sustainable future, and water pollution is a serious problem of current society. Photocatalysis is also an essential route for the degradation of organic dyes in wastewater. A type of compound with the defined structure of perovskite (ABX3) was observed to play important roles in photocatalysis and photovoltaics. These materials can be used as photocatalysts for water splitting reaction for hydrogen production and photo-degradation of organic dyes in wastewater as well as for photoanodes in dye-sensitized solar cells and light absorbers in perovskite-based solar cells for electricity generation. In this review paper, the recent progress of perovskites for applications in these fields is comprehensively summarized. A description of the basic principles of the water splitting reaction, photo-degradation of organic dyes and solar cells as well as the requirements for efficient photocatalysts is first provided. Then, emphasis is placed on the designation and strategies for perovskite catalysts to improve their photocatalytic activity and/or light adsorption capability. Comments on current and future challenges are also provided. The main purpose of this review paper is to provide a current summary of recent progress in perovskite materials for use in these important areas and to provide some useful guidelines for future development in these hot research areas. PMID:25976276

  17. One-dimensional hybrid nanostructures for heterogeneous photocatalysis and photoelectrocatalysis.

    PubMed

    Xiao, Fang-Xing; Miao, Jianwei; Tao, Hua Bing; Hung, Sung-Fu; Wang, Hsin-Yi; Yang, Hong Bin; Chen, Jiazang; Chen, Rong; Liu, Bin

    2015-05-01

    Semiconductor-based photocatalysis and photoelectrocatalysis have received considerable attention as alternative approaches for solar energy harvesting and storage. The photocatalytic or photoelectrocatalytic performance of a semiconductor is closely related to the design of the semiconductor at the nanoscale. Among various nanostructures, one-dimensional (1D) nanostructured photocatalysts and photoelectrodes have attracted increasing interest owing to their unique optical, structural, and electronic advantages. In this article, a comprehensive review of the current research efforts towards the development of 1D semiconductor nanomaterials for heterogeneous photocatalysis and photoelectrocatalysis is provided and, in particular, a discussion of how to overcome the challenges for achieving full potential of 1D nanostructures is presented. It is anticipated that this review will afford enriched information on the rational exploration of the structural and electronic properties of 1D semiconductor nanostructures for achieving more efficient 1D nanostructure-based photocatalysts and photoelectrodes for high-efficiency solar energy conversion. PMID:25641821

  18. Degradation of 4-chlorophenol by a microwave assisted photocatalysis method.

    PubMed

    Ai, Zhihui; Yang, Peng; Lu, Xiaohua

    2005-09-30

    In this work, the degradation of 4-chlorophenol (4CP) under simultaneous microwave assisted UV (electrodeless discharge lamp) photocatalysis technique (MW/UV/TiO2) was investigated. Several factors affecting the degradation of 4CP by MW/UV/TiO2 method, such as the dosage of photocatalysts, the initial pH value of the solutions, gas bubbling, light intensity and addition of H2O2 oxidant, were studied in detail. The synergistic effects between microwave irradiation and TiO2 photocatalysis were also studied. The major intermediates were found to be chlorobenzene, phenol, hydroquinone, benzoquinone and 4-chlorocatechol. Based on the results, a general reaction pathway for the degradation of 4CP was proposed. PMID:15979787

  19. SOME RECENT STUDIES IN RUGHENIUM ELECTROCHEMISTRY AND ELECTROCATALYSIS.

    SciTech Connect

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

    2006-08-01

    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.

  20. New Electrochemical Methods for Studying Nanoparticle Electrocatalysis and Neuronal Exocytosis

    NASA Astrophysics Data System (ADS)

    Cox, Jonathan T.

    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.

  1. Roles of cocatalysts in photocatalysis and photoelectrocatalysis.

    PubMed

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

    2013-08-20

    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

  2. Non-thermal Plasma - Nanometer TiO2 Photocatalysis for Formaldehyde Decomposition 

    E-print Network

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

    2006-01-01

    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...

  3. Hot Electron of Au Nanorods Activates the Electrocatalysis of Hydrogen Evolution on MoS2 Nanosheets.

    PubMed

    Shi, Yi; Wang, Jiong; Wang, Chen; Zhai, Ting-Ting; Bao, Wen-Jing; Xu, Jing-Juan; Xia, Xing-Hua; Chen, Hong-Yuan

    2015-06-17

    Efficient water splitting through electrocatalysis holds great promise for producing hydrogen fuel in modern energy devices. Its real application however suffers from sluggish reaction kinetics due to the lack of high-performance catalysts except noble metals such as platinum. Herein, we report an active system of plasmonic-metal Au nanorods/molybdenum disulfide (MoS2) nanosheets hybrids for the hydrogen evolution reaction (HER). The plasmonic Au-MoS2 hybrids dramatically improve the HER, leading to a ?3-fold increase of current under excitation of Au localized surface plasmon resonance (LSPR). A turnover of 8.76 s(-1) at 300 mV overpotential is measured under LSPR excitation, which by far exceeds the activity of MoS2 catalysts reported recently. The HER enhancement can be largely attributed to the increase of carrier density in MoS2 induced by the injection of hot electrons of Au nanorods. We demonstrate that the synergistic effect of the hole scavengers can further facilitate electron-hole separation, resulting in a decrease of the overpotential of HER at MoS2 to ?120 mV. This study highlights how metal LSPR activates the HER and promises novel opportunities for enhancing intrinsic activities of semiconducting materials. PMID:26020144

  4. Friedel-Crafts Amidoalkylation via Thermolysis and Oxidative Photocatalysis

    PubMed Central

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

    2012-01-01

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

  5. A Surface Science Perspective on TiO2 Photocatalysis

    SciTech Connect

    Henderson, Michael A.

    2011-06-15

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

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

    SciTech Connect

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

    2010-10-01

    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.

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

    PubMed Central

    Yoon, Tehshik P.

    2013-01-01

    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

  8. Degradation of industrial surfactants by photocatalysis combined with ozonation.

    PubMed

    Zsilák, Zoltán; Fónagy, Orsolya; Szabó-Bárdos, Erzsébet; Horváth, Ottó; Horváth, Krisztián; Hajós, Péter

    2014-10-01

    The efficiency of titanium dioxide-mediated photocatalytic degradation of pollutants can be enhanced by combination with another advanced oxidation procedure such as ozonation. Mineralization of hydroxy- and dihydroxybenzenesulfonate based on these methods, both individually and combined, was investigated by monitoring the total organic carbon content, sulfate concentration, pH, high-performance liquid chromatography as well as the absorption spectral changes. The mineralization efficiency of the combined procedure significantly exceeded the sum of those of the individual techniques. The comparison of the disappearance of the starting material and the formation of the sulfate ions indicates that desulfonation is not the primary step of the degradation. Moreover, in the case of the combined method, ring cleavage, and thus, partial mineralization can occur without desulfonation. Efficient degradation of other, widely used industrial surfactants, such as alkylbenzene sulfonates and alkyl ether sulfates, was also achieved by heterogeneous photocatalysis combined with ozonation, offering an applicable method for the removal of these pollutants. PMID:24448882

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

    PubMed

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

    2013-10-15

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

  10. Rare-earth doped colour tuneable up-conversion ZBLAN phosphor for enhancing photocatalysis

    NASA Astrophysics Data System (ADS)

    Méndez-Ramos, J.; Acosta-Mora, P.; Ruiz-Morales, J. C.; Sierra, M.; Redondas, A.; Ruggiero, E.; Salassa, L.; Borges, M. E.; Esparza, P.

    2015-03-01

    Rare-earth doped ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) fluoride glasses have been successfully synthesized showing outstanding UV-VIS up-conversion luminescence of Er3+ and Tm3+, sensitized by Yb3+ ions, under near-infrared excitation at 980 nm. The ratio between blue, green and red up-conversion emission bands can be adjusted by varying the pump power density of the incident infrared radiation, resulting in a controlled tuneability of the overall emitting colour from greenish to yellowish. Additionally, the observed high energy UV intense up-conversion emissions are suitable to enhance photocatalytic activity of main water-splitting semiconductor electrodes (such as TiO2) used in sustainable production of hydrogen. Photocatalysis and photolysis degradation of methylene blue in water under sun-like irradiation using benchmark photocatalyst (TiO2 Degussa P25) have been boosted by 20% and by a factor of 2.5 respectively, due to the enhancement of UV radiation that reaches the TiO2 particles by the addition of ZBLAN powder into a slurry-type photo-reactor. Hence, up-conversion ZBLAN phosphors contribute to demonstrate the possibility of transforming the incoming infrared radiation into the UV region needed to bridge the gap of photocatalytic semiconductors.

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

    PubMed

    Ide, Yusuke; Koike, Yusuke; Ogawa, Makoto

    2011-06-01

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

  12. CO2 SEQUESTRATION AND RECYCLE BY PHOTOCATALYSIS WITH VISIBLE LIGHT

    SciTech Connect

    Steven S.C. Chuang

    1999-12-31

    Photocatalysis could provide a cost-effective route to recycle CO{sub 2} to useful chemicals or fuels. Development of an effective catalyst for the photocatalytic synthesis requires (i) the knowledge of the surface band gap and its relation to the surface structure, (ii) the reactivity of adsorbates and their reaction pathways, and (iii) the ability to manipulate the actives site for adsorption, surface reaction, and electron transfer. The research tasks accomplished during first six months include setting up a photo-catalytic reactor, optical bench, calibration of gas chromatograph, catalyst preparation, and catalyst screening study. Addition of Pt and Cu on TiO{sub 2} was found to increase the activity of TiO{sub 2} catalysts for the synthesis of methanol and methane. The most active catalysts obtained from this study will be used for mechanistic study. The overall goal of this research is to provide a greater predictive capability for the design of visible light-photosynthesis catalysts by a deeper understanding of the reaction kinetics and mechanism as well as by better control of the coordination/chemical environment of active sites.

  13. CO2 SEQUESTRATION AND RECYCLE BY PHOTOCATALYSIS WITH VISIBLE LIGHT

    SciTech Connect

    Steven S.C. Chuang

    2001-10-01

    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.

  14. Photocatalytic oxidation of grey water over titanium dioxide suspensions

    Microsoft Academic Search

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

    2010-01-01

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

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

    E-print Network

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

    2006-01-01

    ICEBO2006, Shenzhen, China Maximize Comfort: Temperature, Humidity, and IAQ Vol. I-3-3 Experiment on TiO2/AC Photocatalysis Technique to Eliminate Toluene in Air Conditioning Systems Yanjun Hu Guohui Feng Quan Yuan Ph.D. Ph.D. Master...

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

    Microsoft Academic Search

    Alexander Samokhvalov

    2012-01-01

    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

  17. Water Purification Systems

    NASA Technical Reports Server (NTRS)

    1992-01-01

    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.

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

    PubMed

    Affam, Augustine Chioma; Chaudhuri, Malay

    2013-11-30

    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

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  20. Development of Cobalt Hydroxide as a Bifunctional Catalyst for Oxygen Electrocatalysis in Alkaline Solution.

    PubMed

    Zhan, Yi; Du, Guojun; Yang, Shiliu; Xu, Chaohe; Lu, Meihua; Liu, Zhaolin; Lee, Jim Yang

    2015-06-17

    Co(OH)2 in the form of hexagonal nanoplates synthesized by a simple hydrothermal reaction has shown even greater activity than cobalt oxides (CoO and Co3O4) in oxygen reduction and oxygen evolution reactions (ORR and OER) under alkaline conditions. The bifunctionality for oxygen electrocatalysis as shown by the OER-ORR potential difference (?E) could be reduced to as low as 0.87 V, comparable to the state-of-the-art non-noble bifunctional catalysts, when the Co(OH)2 nanoplates were compounded with nitrogen-doped reduced graphene oxide (N-rGO). The good performance was attributed to the nanosizing of Co(OH)2 and the synergistic interaction between Co(OH)2 and N-rGO. A zinc-air cell assembled with a Co(OH)2-air electrode also showed a performance comparable to that of the state-of-the-art zinc-air cells. The combination of bifunctional activity and operational stability establishes Co(OH)2 as an effective low-cost alternative to the platinum group metal catalysts. PMID:25997179

  1. Electrocatalysis of formic acid on palladium and platinum surfaces: from fundamental mechanisms to fuel cell applications.

    PubMed

    Jiang, Kun; Zhang, Han-Xuan; Zou, Shouzhong; Cai, Wen-Bin

    2014-10-14

    Formic acid as a natural biomass and a CO2 reduction product has attracted considerable interest in renewable energy exploitation, serving as both a promising candidate for chemical hydrogen storage material and a direct fuel for low temperature liquid fed fuel cells. In addition to its chemical dehydrogenation, formic acid oxidation (FAO) is a model reaction in the study of electrocatalysis of C1 molecules and the anode reaction in direct formic acid fuel cells (DFAFCs). Thanks to a deeper mechanistic understanding of FAO on Pt and Pd surfaces brought about by recent advances in the fundamental investigations, the "synthesis-by-design" concept has become a mainstream idea to attain high-performance Pt- and Pd-based nanocatalysts. As a result, a large number of efficient nanocatalysts have been obtained through different synthesis strategies by tailoring geometric and electronic structures of the two primary catalytic metals. In this paper, we provide a brief overview of recent progress in the mechanistic studies of FAO, the synthesis of novel Pd- and Pt-based nanocatalysts as well as their practical applications in DFAFCs with a focus on discussing studies significantly contributing to these areas in the past five years. PMID:25144896

  2. Oxidation state changes and electron flow in enzymatic catalysis and electrocatalysis through Wannier-function analysis.

    PubMed

    Sit, Patrick H-L; Zipoli, Federico; Chen, Jia; Car, Roberto; Cohen, Morrel H; Selloni, Annabella

    2011-10-17

    In catalysis by metalloenzymes and in electrocatalysis by clusters related in structure and composition to the active components of such enzymes transition-metal atoms can play a central role in the catalyzed redox reactions. Changes to their oxidation states (OSs) are critical for understanding the reactions. The OS is a local property and we introduce a new, generally useful local method for determining OSs, their changes, and the associated bonding changes and electron flow. The method is based on computing optimally localized orbitals (OLOs). With this method, we analyze two cases, superoxide reductase (SOR) and a proposed hydrogen-producing model electrocatalyst [FeS(2)]/[FeFe](P), a modification of the active site of the diiron hydrogenase enzymes. Both utilize an under-coordinated Fe site where a one-electron reduction (for SOR) or a two-electron reduction (for [FeFe](P)) of the substrate occurs. We obtain the oxidation states of the Fe atoms and of their critical ligands, the changes of the bonds to those ligands, and the electron flow during the catalytic cycle, thereby demonstrating that OLOs constitute a powerful interpretive tool for unraveling reaction mechanisms by first-principles computations. PMID:21905140

  3. Direct electrochemistry and electrocatalysis of horseradish peroxidase immobilized in hyaluronic acid and single walled carbon nanotubes composite film

    Microsoft Academic Search

    Qi Wang; Jianbin Zheng

    2010-01-01

    Direct electrochemistry and electrocatalysis of horseradish peroxidase (HRP) immobilized on a hyaluronic acid (HA)-single\\u000a walled carbon nanotubes (SCNs) composite film coated glassy carbon electrode (GCE) was studied for the first time. HRP entrapped\\u000a in the SCNs-HA composite film exhibited a pair of well-defined, quasi-reversible cyclic voltammetric peaks in a 0.1 M phosphate\\u000a buffer solution (pH 7.0). Formal potential vs. standard

  4. Plasmonic hot electron enhanced MoS2 photocatalysis in hydrogen evolution

    NASA Astrophysics Data System (ADS)

    Kang, Yimin; Gong, Yongji; Hu, Zhijian; Li, Ziwei; Qiu, Ziwei; Zhu, Xing; Ajayan, Pulickel M.; Fang, Zheyu

    2015-02-01

    With plasmonic hot electron doping, the molybdenum disulfide (MoS2) monolayer with deposited Au@Ag nanorattles effectively enhanced the hydrogen evolution reaction (HER) efficiency. The maximum photocatalysis is achieved under plasmon resonance excitation, and is actively controlled by the incident laser wavelength and power intensity. The localized phase transition of MoS2 is achieved and characterized to explicate this plasmon-enhanced hydrogen evolution. The proposed MoS2-nanoparticle composite combines surface plasmons and planar 2D materials, and pioneers a frontier field of plasmonic MoS2 photocatalysis.With plasmonic hot electron doping, the molybdenum disulfide (MoS2) monolayer with deposited Au@Ag nanorattles effectively enhanced the hydrogen evolution reaction (HER) efficiency. The maximum photocatalysis is achieved under plasmon resonance excitation, and is actively controlled by the incident laser wavelength and power intensity. The localized phase transition of MoS2 is achieved and characterized to explicate this plasmon-enhanced hydrogen evolution. The proposed MoS2-nanoparticle composite combines surface plasmons and planar 2D materials, and pioneers a frontier field of plasmonic MoS2 photocatalysis. Electronic supplementary information (ESI) available: SEM images of the as-grown 2H-MoS2 on a Si substrate and Ag@Au nanorattles; extinction spectrum of Ag@Au nanorattles; HER polarization curves under 690 nm laser illumination for Si and MoS2, respectively; calculated near-field optical intensity map of Ag@Ag nanorattles; HER polarization curves under 690 nm laser illumination for the MoS2 monolayer with Ag@Au nanorattles. See DOI: 10.1039/c4nr07303g

  5. The Continuous Desulfurization of FCC Gasoline through Extraction and Photocatalysis-oxidation

    Microsoft Academic Search

    Y.-R. Xu; B. Shen; L. Wang; X. Wu

    2011-01-01

    Removal of sulfur-containing compounds from gasoline, based on the combination of various technologies (liquid-liquid extraction and extraction- photocatalysis-oxidation desulfurization) using a biphasic system (oil\\/acetonitrile) has been investigated. The effect of operation conditions on desulfurization rates and the distribution coefficient in a model system for gasoline were explored. Additionally, extraction-desulfurization kinetics are studied through simulation; the kinetics equation, (?rA) = 7.1cA

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

    PubMed Central

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

    2014-01-01

    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

  7. Hydrocarbon removal from bilgewater by a combination of air-stripping and photocatalysis.

    PubMed

    Cazoir, D; Fine, L; Ferronato, C; Chovelon, J-M

    2012-10-15

    In order to prevent hydrocarbon discharge at sea from the bilge of ships, the International Maritime Organization (IMO) enacted the MARPOL 73/78 convention in which effluents are now limited to those with maximum oil content of 15 ppmv. Thus, photocatalysis and air-stripping were combined for the hydrocarbon removal from a real oily bilgewater sample and an original monitoring of both aqueous and gaseous phases was performed by GC/MS to better understand the process. Our results show that the hydrocarbon oil index [HC] can be reduced to its maximum permissible value of 15 ppmv (MARPOL) in only 8.5h when photocatalysis and air-stripping are used together in a synergistic way, as against 17 h when photocatalysis is used alone. However, this air-assisted photocatalytic process emits a large quantity of volatile organic compounds (VOC) and, within the first four hours, ca. 10% of the hydrocarbon removal in the aqueous phase is actually just transferred into the gaseous one. Finally, we highlight that the n-alkanes with a number of carbon atoms higher than 15 (N(C)>15) are those which most decrease the rate of [HC] removal. PMID:22871416

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

    PubMed Central

    Samhaber, Wolfgang M

    2014-01-01

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

  9. Development of a new photocatalytic reactor for water purification

    Microsoft Academic Search

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

    1998-01-01

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

  10. Ligand-exchange assisted formation of Au/TiO2 Schottky contact for visible-light photocatalysis.

    PubMed

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

    2014-11-12

    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

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

    PubMed Central

    2014-01-01

    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

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

    PubMed

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

    2014-01-01

    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

  13. Fighting global warming: The potential of photocatalysis against CO 2, CH 4, N 2O, CFCs, tropospheric O 3, BC and other major contributors to climate change

    Microsoft Academic Search

    Sylvain Caillol

    2011-01-01

    At the laboratory scale, photocatalysis is a promising method to convert many air pollutants such as nitrogen oxides and volatile organic compounds, to safer products for human health but also environmentally more acceptable, such as nitrate and carbon dioxide.Indoor and industrial applications of photocatalysis to remove local air pollutants from the atmosphere are now numerous. Large scale outdoor applications of

  14. 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

    Kristof Demeestere; Jo Dewulf; Herman Van Langenhove

    2007-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  16. Flower-Like Nanoparticles of Pt-BiIII Assembled on Agmatine Sulfate Modified Glassy Carbon Electrode and Their Electrocatalysis of H2O2

    NASA Astrophysics Data System (ADS)

    Xiao, Mingshu; Yan, Yuhua; Feng, Kai; Tian, Yanping; Miao, Yuqing

    2015-04-01

    A new electrochemical technique to detect hydrogen peroxide (H2O2) was developed. The Pt nanoparticles and BiIII were subsequently assembled on agmatine sulfate (AS) modified glassy carbon electrode (GCE) and the prepared GCE-AS-Pt-BiIII was characterized by scanning electron microscopy (SEM) with result showing that the flower-like nanostructure of Pt-BiIII was yielded. Compared with Pt nanoparticles, the flower-like nanostructure of Pt-BiIII greatly enhanced the electrocatalysis of GCE-AS-Pt-BiIII towards H2O2, which is ascribed to more Pt-OH obtained on GCE-AS-Pt-BiIII surface for the presence of BiIII. Based on its high electrocatalysis, GCE-AS-Pt-BiIII was used to determine the content of H2O2 in the sample of sheet bean curd with standard addition method. Meantime, its electrocatalytic activity also was studied.

  17. Conjugated polymer/nanocrystal nanocomposites for renewable energy applications in photovoltaics and photocatalysis.

    PubMed

    Su, Yu-Wei; Lin, Wei-Hao; Hsu, Yung-Jung; Wei, Kung-Hwa

    2014-11-01

    Conjugated polymer/nanocrystal composites have attracted much attention for use in renewable energy applications because of their versatile and synergistic optical and electronic properties. Upon absorbing photons, charge separation occurs in the nanocrystals, generating electrons and holes for photocurrent flow or reduction/oxidation (redox) reactions under proper conditions. Incorporating these nanocrystals into conjugated polymers can complement the visible light absorption range of the polymers for photovoltaics applications or allow the polymers to sensitize or immobilize the nanocrystals for photocatalysis. Here, the current developments of conjugated polymer/nanocrystal nanocomposites for bulk heterojunction-type photovoltaics incorporating Cd- and Pb-based nanocrystals or quantum dots are reviewed. The effects of manipulating the organic ligands and the concentration of the nanocrystal precursor, critical factors that affect the shape and aggregation of the nanocrystals, are also discussed. In the conclusion, the mechanisms through which conjugated polymers can sensitize semiconductor nanocrystals (TiO2 , ZnO) to ensure efficient charge separation, as well as how they can support immobilized nanocrystals for use in photocatalysis, are addressed. PMID:25074641

  18. Tungsten oxide--fly ash oxide composites in adsorption and photocatalysis.

    PubMed

    Visa, Maria; Bogatu, Cristina; Duta, Anca

    2015-05-30

    A novel composite based on tungsten oxide and fly ash was hydrothermally synthetized to be used as substrate in the advanced treatment of wastewaters with complex load resulted from the textile industry. The proposed treatment consists of one single step process combining photocatalysis and adsorption. The composite's crystalline structure was investigated by X-ray diffraction and FTIR, while atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to analyze the morphology. The adsorption capacity and photocatalytic properties of the material were tested on mono- and multi-pollutants systems containing two dyes (Bemacid Blau - BB and Bemacid Rot - BR) and one heavy metal ion-Cu(2+), and the optimized process conditions were identified. The results indicate better removal efficiencies using the novel composite material in the combined adsorption and photocatalysis, as compared to the separated processes. Dyes removal was significantly enhanced in the photocatalytic process by adding hydrogen peroxide and the mechanism was presented and discussed. The pseudo second order kinetics model best fitted the experimental data, both in the adsorption and in the combined processes. The kinetic parameters were calculated and correlated with the properties of the composite substrate. PMID:25733398

  19. Mechanism of enhanced photocatalysis of TiO 2 by Fe 3+ in suspensions

    NASA Astrophysics Data System (ADS)

    Zhang, Junwei; Fu, Dafang; Gao, Haiying; Deng, Lin

    2011-12-01

    In this work, the mechanism of enhanced photocatalysis of TiO2 with Fe3+ was studied using Sulfadiazine (SD) as the model compound. Results indicated that degradation rate of SD was enhanced by the addition of Fe3+ in TiO2 suspension. The crystalline structure of TiO2 particles was stable in suspensions. The hydroxyl radical generated by TiO2/Fe3+ (both TiO2 and Fe3+) photocatalysis was in a higher yield. Moreover, Fe2+ was found not to give an obvious impact on the SD degradation in TiO2 suspension, whereas Fe3+ had a notable effect. The adsorption amount of TiO2 was greatly enhanced by the addition of Fe3+ in suspensions. Finally, an interaction model of SD degradation in TiO2 suspension containing Fe3+ was also proposed by investigating of surface behaviors of TiO2 particles. It will be beneficial to use Fe3+ as the electron acceptors on the surface of TiO2 particles, which helps to improve the yield of hydroxyl radical.

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

    PubMed

    Egerton, Terry A

    2014-01-01

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

  1. Growth of oriented vanadium pentaoxide nanostructures on transparent conducting substrates and their applications in photocatalysis

    SciTech Connect

    Liu, Hongjiang [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Dingxi 1295, Changning, Shanghai 200050 (China); Gao, Yanfeng, E-mail: gaosic@gmail.com [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Dingxi 1295, Changning, Shanghai 200050 (China); School of Materials Science and Engineering, Shanghai University, Shangda Rd. 99, Baoshan, Shanghai 200444 (China); Zhou, Jiadong [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Dingxi 1295, Changning, Shanghai 200050 (China); Liu, Xinling [School of Materials Science and Engineering, Shanghai University, Shangda Rd. 99, Baoshan, Shanghai 200444 (China); Chen, Zhang; Cao, Chuanxiang [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Dingxi 1295, Changning, Shanghai 200050 (China); Luo, Hongjie [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Dingxi 1295, Changning, Shanghai 200050 (China); School of Materials Science and Engineering, Shanghai University, Shangda Rd. 99, Baoshan, Shanghai 200444 (China); Kanehira, Minoru [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Dingxi 1295, Changning, Shanghai 200050 (China)

    2014-06-01

    A novel, hydrothermal and hard-template-free method was developed for the first time to grow oriented, single-crystalline monoclinic VO{sub 2} (B) flower-like nanorod films on transparent conductive fluorine-doped tin oxide (FTO) substrates. The length and morphology of the nanorods can be tuned by changing the growth parameters, such as growth time and initial precursor concentration. The flower-like V{sub 2}O{sub 5} films were obtained after post-calcination treatment of VO{sub 2} (B) films. The photocatalytic activity of V{sub 2}O{sub 5} films was investigated by the degradation of methylene blue (MB) under UV and visible light. The prepared V{sub 2}O{sub 5} film exhibited good photocatalytic performance (74.6% and 63% under UV and visible light for 210 min, respectively) and more practical application in industry. - Graphical abstract: Flower nanostructured vanadium oxide film was prepared by hydrothermal reaction for photocatalysis application. - Highlights: • Monoclinic VO{sub 2} nanorod array and flower-like nanostructure were directly grown on FTO substrate by hydrothermal reaction. • The growth mechanism was analyzed by FESEM at different time. • V{sub 2}O{sub 5} flower-like nanostructure film was obtained after calcining VO{sub 2} film. • V{sub 2}O{sub 5} film exhibited good light activity and potential application in photocatalysis.

  2. Rational design of carbon and TiO2 assembly materials: covered or strewn, which is better for photocatalysis?

    PubMed

    Cui, Guan-wei; Wang, Wei-liang; Ma, Ming-yue; Zhang, Ming; Xia, Xin-yuan; Han, Feng-yun; Shi, Xi-feng; Zhao, Ying-qiang; Dong, Yu-bin; Tang, Bo

    2013-07-21

    The rational design of carbonaceous hybrid nanostructures is very important for obtaining high photoactivity. TiO2 particles strewn with an optimal quantity of carbon nanodots have a much higher photoactivity than that of TiO2 covered with a carbon layer, showing the importance of carbon morphology in the photocatalysis of carbonaceous hybrid nanostructures. PMID:23752661

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

    PubMed

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

    2007-07-31

    In this paper, photoelectro-synergistic catalysis oxidation of organics in the water on Ti/TiO(2)/PbO(2) electrode was investigated. The prepared TiO(2) 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 (COD) values. It was shown that the method of photoelectro-synergistic catalysis had lower detection limit (15.0mg l(-1)) and wider linear range (30.0-2500.0mg l(-1)) than the methods of electro-assisted photocatalysis and electrocatalysis. The results obtained by the proposed method and conventional one were compared by carrying out the experiment on 20 wastewater samples and also agreed well by high correlation (R=0.9912). PMID:19071828

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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.

  5. Growth of non-phototrophic microorganisms using solar energy through mineral photocatalysis.

    PubMed

    Lu, Anhuai; Li, Yan; Jin, Song; Wang, Xin; Wu, Xiao-Lei; Zeng, Cuiping; Li, Yan; Ding, Hongrui; Hao, Ruixia; Lv, Ming; Wang, Changqiu; Tang, Yueqin; Dong, Hailiang

    2012-01-01

    Phototrophy and chemotrophy are two dominant modes of microbial metabolism. To date, non-phototrophic microorganisms have been excluded from the solar light-centered phototrophic metabolism. Here we report a pathway that demonstrates a role of light in non-phototrophic microbial activity. In lab simulations, visible light-excited photoelectrons from metal oxide, metal sulfide, and iron oxide stimulated the growth of chemoautotrophic and heterotrophic bacteria. The measured bacterial growth was dependent on light wavelength and intensity, and the growth pattern matched the light absorption spectra of the minerals. The photon-to-biomass conversion efficiency was in the range of 0.13-1.90‰. Similar observations were obtained in a natural soil sample containing both bacteria and semiconducting minerals. Results from this study provide evidence for a newly identified, but possibly long-existing pathway, in which the metabolisms and growth of non-phototrophic bacteria can be stimulated by solar light through photocatalysis of semiconducting minerals. PMID:22473012

  6. Dielectric Barrier Discharge Plasma-Induced Photocatalysis and Ozonation for the Treatment of Wastewater

    NASA Astrophysics Data System (ADS)

    Mok, Young Sun; Jo, Jin-Oh; Lee, Heon-Ju

    2008-02-01

    The physicochemical processes of dielectric barrier discharge (DBD) such as in-situ formation of chemically active species and emission of ultraviolet (UV)/visible light were utilized for the treatment of a simulated wastewater formed with Acid Red 4 as the model organic contaminant. The chemically active species (mostly ozone) produced in the DBD reactor were well distributed in the wastewater using a porous gas diffuser, thereby increasing the gas-liquid contact area. For the purpose of making the best use of the light emission, a titanium oxide-based photocatalyst was incorporated in the wastewater treating system. The experimental parameters chosen were the voltage applied to the DBD reactor, the initial pH of the wastewater, and the concentration of hydrogen peroxide added to the wastewater. The results have clearly shown that the present system capable of degrading organic contaminants in two ways (photocatalysis and ozonation) may be a promising wastewater treatment technology.

  7. Effect of Morphology of Co3O4 for Oxygen Evolution Reaction in Alkaline Water Electrolysis

    PubMed Central

    Xu, Qi-Zhi; Xu, Qi-Zhi; Su, Yu-Zhi; Wu, Hao; Cheng, Hui; Hui, Yun-Ping; Li, Nan; Liu, Zhao-Qing

    2014-01-01

    In this paper, three different morphological Co3O4 electrodes for oxygen evolution reaction (OER) have been synthesized. By comparing the three morphologies of Co3O4, the electrocatalytic properties show that the urchin-like spheres of Co3O4 electrode has relative low overpotential and good electrocatalysis stability, indicating that the structure of urchin-like Co3O4 spheres exhibit an easy OER for water splitting. PMID:25525423

  8. Photocatalytic purification and remediation of contaminated air and water

    Microsoft Academic Search

    David F Ollis

    2000-01-01

    Among the catalytic approaches to environmental remediation, that of heterogeneous photoassisted catalysis, known as ‘photocatalysis’, is the sole example involving utilization of light along with a catalytic solid. This paper surveys the broad range of emerging potential applications for water (contaminant destruction and removal, metal deposition and recovery, sterilization and disinfection) then for air (purification, decontamination, deodorization, bioaerosol removal, self-cleaning

  9. Molecular-Level Insights into Photocatalysis from Scanning Probe Microscopy Studies on TiO2(110)

    SciTech Connect

    Henderson, Michael A.; Lyubinetsky, Igor

    2013-06-12

    The field of heterogeneous photocatalysis has grown considerably in the decades since Fujishima and Honda's ground-breaking publications of photoelectrochemistry on TiO2. Numerous review articles continue to point to both progress made in the use of heterogeneous materials (such as TiO2) to perform photoconversion processes, and the many opportunities and challenges in heterogeneous photocatalysis research such as solar energy conversion and environmental remediation. The past decade has also seen an increase in the use of molecular-level approaches applied to model single crystal surfaces in an effort to obtain new insights into photocatalytic phenomena. In particular, scanning probe techniques (SPM) have enabled researchers to take a ‘nanoscale’ approach to photocatalysis that includes interrogation of the reactivities of specific sites and adsorbates on a model photocatalyst surface. The rutile TiO2(110) surface has become the prototypical oxide single crystal surface for fundamental studies of many interfacial phenomena. In particular, TiO2(110) has become an excellent model surface for probing photochemical and photocatalytic reactions at the molecular level. A variety of experimental approaches have emerged as being ideally suited for studying photochemical reactions on TiO2(110), including desorption-oriented approaches and electronic spectroscopies, but perhaps the most promising techniques for evaluating site-specific properties are those of SPM. In this review, we highlight the growing use of SPM techniques in providing molecular-level insights into surface photochemistry on the model photocatalyst surface of rutile TiO2(110). Our objective is to both illustrate the unique knowledge that scanning probe techniques have already provided the field of photocatalysis, and also to motivate a new generation of effort into the use of such approaches to obtain new insights into the molecular level details of photochemical events occurring at interfaces. Discussion will start with an examination of how scanning probe techniques are being used to characterize the TiO2(110) surface in ways that are relevant to photocatalysis. We will then discuss specific classes of photochemical reaction on TiO2(110) for which SPM has proven indispensible in providing unique molecular-level insights, and conclude with discussion of future areas in which SPM studies may prove valuable to photocatalysis on TiO2. This work was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. I.L. was partially supported by a Pacific Northwest National Laboratory (PNNL) Chemical Imaging Initiative project. PNNL is a multiprogram national laboratory operated for DOE by Battelle.

  10. 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-...

  11. Theory and experiments for voltammetric and SECM investigations and application to ORR electrocatalysis at nanoelectrode ensembles of ultramicroelectrode dimensions.

    PubMed

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

    2015-01-20

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

  12. Microwave photocatalysis of mono-chloroacetic acid over nanoporous titanium(IV) oxide thin films using mercury electrodeless discharge lamps

    Microsoft Academic Search

    Vladimír Církva; Hana Žabová; Milan Hájek

    2008-01-01

    The degradation of mono-chloroacetic acid (MCAA) by microwave-assisted photocatalysis has been examined by a new method. A novel electrodeless discharge lamp (EDL) was employed as UV light source generated by microwave irradiation. Titanium(IV) oxide film was used as the photocatalyst due to its superior characteristics. Several factors influencing the degradation of MCAA, such as number of coating cycles, light intensity,

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

    Microsoft Academic Search

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

    2011-01-01

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

  14. Toward highly efficient photocatalysis: a flow-through Pt@TiO?@AAO membrane nanoreactor prepared by atomic layer deposition.

    PubMed

    Chen, Hsueh-Shih; Chen, Po-Hsun; Huang, Sheng-Hsin; Perng, Tsong-Pyng

    2014-04-28

    A Pt@TiO2@AAO membrane nanoreactor was fabricated by atomic layer deposition. The photodegradation test of methylene blue demonstrated that the nanoreactor shows efficient photocatalysis performance. It exhibited ~28% photodegradation of methylene blue after ten flow-through cycles, corresponding to about 2.7 × 10(-2) s of contact time of methylene blue with Pt@TiO2 nanotubes. PMID:24643760

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    Anatase/rutile mixed titania nanotubes (TiO2 NTs) precipitated with gold nanoparticles (Au NPs), i.e. Au/TiO2, have been synthesized and investigated on visible photocatalysis properties. A deposition-precipitation (DP) method was adopted to reduce the gold precursor to Au NPs within the preformed TiO2 NTs by the emulsion electrospinning technique. The optimal visible photocatalytic activity was found in the sample Au3(DP350)/TiO2 with a loading of 3 wt% Au NPs and calcining at 350 °C. Through transmission electron microscopy, Au NPs of 4.16 nm diameter were observed at the interface between the anatase and rutile phases in the optimal Au3(DP350)/TiO2 sample, and these joint active sites at the interface were beneficial for charge separation. The obtained optimal photocatalytic efficiency of Au3(DP350)/TiO2 was ascribed to the synergistic effect of the enhanced visible absorption and the anatase/rutile mixed-phase composition, and the possible mechanism for this was discussed in detail.Anatase/rutile mixed titania nanotubes (TiO2 NTs) precipitated with gold nanoparticles (Au NPs), i.e. Au/TiO2, have been synthesized and investigated on visible photocatalysis properties. A deposition-precipitation (DP) method was adopted to reduce the gold precursor to Au NPs within the preformed TiO2 NTs by the emulsion electrospinning technique. The optimal visible photocatalytic activity was found in the sample Au3(DP350)/TiO2 with a loading of 3 wt% Au NPs and calcining at 350 °C. Through transmission electron microscopy, Au NPs of 4.16 nm diameter were observed at the interface between the anatase and rutile phases in the optimal Au3(DP350)/TiO2 sample, and these joint active sites at the interface were beneficial for charge separation. The obtained optimal photocatalytic efficiency of Au3(DP350)/TiO2 was ascribed to the synergistic effect of the enhanced visible absorption and the anatase/rutile mixed-phase composition, and the possible mechanism for this was discussed in detail. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03024e

  16. TiO2-B/anatase core-shell heterojunction nanowires for photocatalysis.

    PubMed

    Liu, Bin; Khare, Ankur; Aydil, Eray S

    2011-11-01

    Fast separation and spatial control of electrons and holes after photogeneration is important in photocatalysis. Ideally, after photogeneration, electrons and holes must be segregated to different parts of the photocatalyst to take part in separate oxidation and reduction reactions. One way to achieve this is by building junctions into the catalyst with built-in chemical potential differences that tend to separate the electron and the hole into two different regions of the catalyst. In this work, we sought to accomplish this by controllably forming junctions between different phases of TiO(2). A synthesis method has been developed to prepare TiO(2)-B core and anatase shell core-shell nanowires. We control the anatase phase surface coverage on the TiO(2)-B core and show that the maximum photocatalytic activity is obtained when the solution containing the reactants can contact both the anatase and TiO(2)-B phases. The photocatalytic activity drops both with bare TiO(2)-B nanowires and with completely anatase covered TiO(2)-B nanowires. In contrast, nanowires partially covered with anatase phase gives the highest photocatalytic activity. The improved photocatalytic activity is attributed to the effective electron-hole separation at the junction between the anatase and TiO(2)-B phases. PMID:22008419

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

    PubMed

    Bagal, Manisha V; Gogate, Parag R

    2014-05-01

    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

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

    PubMed

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

    2012-01-01

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

  19. Artificial Photosystem I and II: Highly Selective solar fuels and tandem photocatalysis

    NASA Astrophysics Data System (ADS)

    Ding, Yuchen; Castellanos, Ignacio; Cerkovnik, Logan; Nagpal, Prashant

    2014-03-01

    Artificial photosynthesis, or generation of solar fuels from CO2/H2O, can provide an important alternative for rising CO2 emission and renewable energy generation. In our recent work, composite photocatalysts (CPCs) made from widebandgap nanotubes and different QDs were used to mimic Photosystem II (PS680) and I (PS700), respectively. By tuning the redox potentials using the size, composition and energy band alignment of QDs, we demonstrate highly selective (>90%) and efficient production of ethane, ethanol and acetaldehyde as solar fuels with different wavelengths of light. We also show that this selectivity is a result of precise energy band alignments (using cationic/anionic doping of nanotubes, QD size etc.), confirmed using measurements of electronic density of states, and alignment of higher redox potentials with hot-carriers can also lead to hot-carrier photocatalysis. This wavelength-selective CPCs can have important implications for inexpensive production of solar fuels including alkanes, alcohols, aldehydes and hydrogen, and making tandem structures (red, green, blue) with three CPCs, allowing almost full visible spectrum (410 ~ 730nm) utilization with different fuels produced simultaneously.

  20. 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 ...

  1. Modelling and design of thin-film slurry photocatalytic reactors for water purification

    Microsoft Academic Search

    Gianluca Li Puma; Po Lock Yue

    2003-01-01

    Photocatalytic oxidation processes are highly effective clean technologies for the degradation and mineralization of a wide variety of priority pollutants in water and wastewater. However, the application of heterogeneous photocatalysis for wastewater treatment on an industrial scale has been impeded by a lack of mathematical models that can be readily applied to reactor design and scale-up. As a results current

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

    PubMed

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

    2014-01-01

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

  3. Water

    MedlinePLUS

    ... to drink more water Other drinks How much water do you need? top Water is very important, ... you probably need more water. What about bottled water? top Some people like bottled water for its ...

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

    PubMed

    Hossaini, Hiwa; Moussavi, Gholamreza; Farrokhi, Mehrdad

    2014-08-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

  6. Gold nanoparticle-decorated keggin ions/TiO2 photococatalyst for improved solar light photocatalysis.

    PubMed

    Pearson, Andrew; Jani, Harit; Kalantar-zadeh, Kourosh; Bhargava, Suresh K; Bansal, Vipul

    2011-06-01

    We demonstrate a facile localized reduction approach to synthesizing a Au nanoparticle-decorated Keggin ion/TiO(2) photococatalyst for improved solar light photocatalysis application. This has been achieved by exploiting the ability of TiO(2)-bound Keggin ions to act as a UV-switchable, highly localized reducing agent. Notably, the approach proposed here does not lead to contamination of the resultant cocatalyst with free metal nanoparticles during aqueous solution-based synthesis. The study shows that for Keggin ions (phosphotungstic acid, PTA), being photoactive molecules, the presence of both Au nanoparticles and PTA on the TiO(2) surface in a cocatalytic system can have a dramatic effect on increasing the photocatalytic performance of the composite system, as opposed to a TiO(2) surface directly decorated with metal nanoparticles without a sandwiched PTA layer. The remarkable increase in the photocatalytic performance of these materials toward the degradation of a model organic Congo red dye correlates to an increase of 2.7-fold over that of anatase TiO(2) after adding Au to it and 4.3-fold after introducing PTA along with Au to it. The generalized localized reduction approach to preparing TiO(2)-PTA-Au cocatalysts reported here can be further extended to other similar systems, wherein a range of metal nanoparticles in the presence of different Keggin ions can be utilized. The composites reported here may have wide potential implications toward the degradation of organic species and solar cell applications. PMID:21534553

  7. 2D Hybrid Nanostructure of Reduced Graphene Oxide-CdS Nanosheet for Enhanced Photocatalysis.

    PubMed

    Bera, Rajesh; Kundu, Simanta; Patra, Amitava

    2015-06-24

    Graphene-based hybrid nanostructures have recently emerged as a new class of functional materials for light-energy conversion and storage. Here, we have synthesized reduced graphene oxide (RGO)-semiconductor composites to improve the efficiency of photocatalysis. Zero-dimensional CdS nanoparticles (0D), one-dimensional CdS nanorods (1D), and two-dimensional CdS nanosheets (2D) are grafted on the RGO sheet (2D) by a surface modification method using 4-aminothiophenol (4-ATP). Structural analysis confirms the attachment of CdS nanocrystals with RGO, and the strong electronic interaction is found in the case of a CdS nanosheet and RGO, which has an influence on photocatalytic properties. The degradation of dye under visible light varies with changing the dimension of nanocrystals, and the catalytic activity of the CdS NS/RGO composite is ?4 times higher than that of CdS nanoparticle/RGO and 3.4 times higher than that of CdS nanorod/RGO composite samples. The catalytic activity of the CdS nanosheet/RGO composite is also found to be ?2.5 times than that of pure CdS nanosheet samples. The unique 2D-2D nanoarchitecture would be effective to harvest photons from solar light and transport electrons to reaction sites with respect to other 0D-2D and 1D-2D hybrid systems. This observation can be extended to other graphene-based inorganic semiconductor composites, which can provide a valuable opportunity to explore novel hybrid materials with superior visible-light-induced catalytic activity. PMID:26029992

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

    SciTech Connect

    Brett Kimball Simpson

    2002-08-27

    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.

  9. Distant protonated pyridine groups in water-soluble iron porphyrin electrocatalysts promote selective oxygen reduction to water

    SciTech Connect

    Matson, Benjamin D.; Carver, Colin T.; Von Ruden, Amber L.; Yang, Jenny Y.; Raugei, Simone; Mayer, James M.

    2012-11-08

    Fe(III)-meso-tetra(pyridyl)porphines are selective electrocatalysts for the reduction of dioxygen to water in aqueous acidic solution. The 2-pyridyl derivatives, both the triflate and chloride salts, are more selective than the isomeric 4-pyridyl complexes. The improved selectivity of is ascribed to the inward-pointing pyridinium groups acting as intramolecular proton relays. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

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

    PubMed

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

    2010-07-19

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

  11. Inactivation of Escherichia coli O157:H7 on Orange Fruit Surfaces and in Juice Using Photocatalysis and High Hydrostatic Pressure.

    PubMed

    Yoo, Sungyul; Ghafoor, Kashif; Kim, Jeong Un; Kim, Sanghun; Jung, Bora; Lee, Dong-Un; Park, Jiyong

    2015-06-01

    Nonpasteurized orange juice is manufactured by squeezing juice from fruit without peel removal. Fruit surfaces may carry pathogenic microorganisms that can contaminate squeezed juice. Titanium dioxide-UVC photocatalysis (TUVP), a nonthermal technique capable of microbial inactivation via generation of hydroxyl radicals, was used to decontaminate orange surfaces. Levels of spot-inoculated Escherichia coli O157:H7 (initial level of 7.0 log CFU/cm(2)) on oranges (12 cm(2)) were reduced by 4.3 log CFU/ml when treated with TUVP (17.2 mW/cm(2)). Reductions of 1.5, 3.9, and 3.6 log CFU/ml were achieved using tap water, chlorine (200 ppm), and UVC alone (23.7 mW/cm(2)), respectively. E. coli O157:H7 in juice from TUVP (17.2 mW/cm(2))-treated oranges was reduced by 1.7 log CFU/ml. After orange juice was treated with high hydrostatic pressure (HHP) at 400 MPa for 1 min without any prior fruit surface disinfection, the level of E. coli O157:H7 was reduced by 2.4 log CFU/ml. However, the E. coli O157:H7 level in juice was reduced by 4.7 log CFU/ml (to lower than the detection limit) when TUVP treatment of oranges was followed by HHP treatment of juice, indicating a synergistic inactivation effect. The inactivation kinetics of E. coli O157:H7 on orange surfaces followed a biphasic model. HHP treatment did not affect the pH, °Brix, or color of juice. However, the ascorbic acid concentration and pectinmethylesterase activity were reduced by 35.1 and 34.7%, respectively. PMID:26038898

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

    PubMed

    Qiu, Bocheng; Xing, Mingyang; Zhang, Jinlong

    2014-04-23

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

  13. Intimate Coupling of Photocatalysis and Biodegradation for Degrading Phenol Using Different Light Types: Visible Light vs UV Light.

    PubMed

    Zhou, Dandan; Xu, Zhengxue; Dong, Shanshan; Huo, Mingxin; Dong, Shuangshi; Tian, Xiadi; Cui, Bin; Xiong, Houfeng; Li, Tingting; Ma, Dongmei

    2015-07-01

    Intimate coupling of photocatalysis and biodegradation (ICPB) technology is attractive for phenolic wastewater treatment, but has only been investigated using UV light (called UPCB). We examined the intimate coupling of visible-light-induced photocatalysis and biodegradation (VPCB) for the first time. Our catalyst was prepared doping both of Er(3+) and YAlO3 into TiO2 which were supported on macroporous carriers. The macroporous carriers was used to support for the biofilms as well. 99.8% removal efficiency of phenol was achieved in the VPCB, and this was 32.6% higher than that in the UPCB. Mineralization capability of UPCB was even worse, due to less adsorbable intermediates and cell lysis induced soluble microbial products release. The lower phenol degradation in the UPCB was due to the serious detachment of the biofilms, and then the microbes responsible for phenol degradation were insufficient due to disinfection by UV irradiation. In contrast, microbial communities in the carriers were well protected under visible light irradiation and extracellular polymeric substances secretion was enhanced. Thus, we found that the photocatalytic reaction and biodegradation were intimately coupled in the VPCB, resulting in 64.0% removal of dissolved organic carbon. Therefore, we found visible light has some advantages over UV light in the ICPB technology. PMID:26076382

  14. 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...

  15. Investigation of electron behavior in Nano-TiO2 photocatalysis by using in situ open-circuit voltage and photoconductivity measurements.

    PubMed

    Liu, Baoshun; Wang, Xuelei; Wen, Liping; Zhao, Xiujian

    2013-08-01

    The in situ open-circuit voltages (Voc ) and the in situ photoconductivities have been measured to study electron behavior in photocatalysis and its effect on the photocatalytic oxidation of methanol. It was observed that electron injection to the conduction band (CB) of TiO2 under light illumination during photocatalysis includes two sources: from the valence band (VB) of TiO2 and from the methanol molecule. The electron injection from methanol to TiO2 is slower than that directly from the VB, which indicates that the adsorption mode of methanol on the TiO2 surface can change between dark and illuminated states. The electron injection from methanol to the CB of TiO2 leads to the upshift of the Fermi level of electrons in TiO2 , which is the thermodynamic driving force of photocatalytic oxidation. It was also found that the charge state of nano-TiO2 is continuously changing during photocatalysis as electrons are injected from methanol to TiO2 . Combined with the apparent Langmuir-Hinshelwood kinetic model, the relation between photocatalytic kinetics and electrons in the TiO2 CB was developed and verified experimentally. The photocatalytic rate constant is the variation of the Fermi level with time, based on which a new method was developed to calculate the photocatalytic kinetic rate constant by monitoring the change of Voc with time during photocatalysis. PMID:23794228

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

    PubMed

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

    2013-09-01

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

  17. Water

    MedlinePLUS

    ... consuming only bottled water or water from a filtration system that has been certified by an independent ... recommends using bottled water or water from a filtration system that has been certified by an independent ...

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

    PubMed Central

    2013-01-01

    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

  19. In situ precipitation preparation of ZnO hollow spheres and their photocatalysis and gas-sensing properties

    NASA Astrophysics Data System (ADS)

    Jia, Xiaohua; Tian, Minggang; Liu, Yingying; Wu, Xiangyang; Song, Haojie

    2015-06-01

    ZnO hollow spheres were synthesized by in situ precipitation method in the presence of surfactant polyvinylpyrrolidone combined with subsequent calcination. The prepared ZnO was characterized using scanning electron microscopy, X-ray diffraction, high-resolution transmission electron microscopy. The results indicated that the prepared ZnO hollow spheres were well crystalline with wurtzite hexagonal phase. The formation mechanism of ZnO hollow spheres was discussed. Furthermore, the gas-sensing properties for detection of organic gas and photocatalytic activities for the degradation of rhodamine B (RhB) of the prepared ZnO hollow spheres were investigated. The results indicated that the prepared ZnO hollow spheres exhibited superior photocatalysis properties on decomposition of RhB and high gas-sensing properties for detection of acetone gas.

  20. Plant uptake-assisted round-the-clock photocatalysis for complete purification of aquaculture wastewater using sunlight.

    PubMed

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

    2015-02-17

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

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

    PubMed

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

    2006-12-01

    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

  2. Two-dimensional transition metal dichalcogenide nanomaterials for solar water splitting

    NASA Astrophysics Data System (ADS)

    Andoshe, Dinsefa M.; Jeon, Jong-Myeong; Kim, Soo Young; Jang, Ho Won

    2015-05-01

    Recently, 2-dimensional (2D) transition metal dichalcogenides (TMDs) have received great attention for solar water splitting and electrocatalysis. In addition to their wide variety of electronic and microstructural properties, their promising catalytic activities for hydrogen production make 2D TMDs as earth-abundant and inexpensive catalysts that can replace noble metals. This paper reviews the electronic, structural, and optical properties of 2D TMDs. We highlight the various synthetic methods for 2D TMDs and their applications in hydrogen evolution based on photoelectrochemical and electrocatalytic cells. We also discuss perspectives and challenges of 2D TMDs for hydrogen production and artificial photosynthesis.[Figure not available: see fulltext.

  3. Photosensitization of TiO 2 by M x O y and M x S y nanoparticles for heterogeneous photocatalysis applications

    Microsoft Academic Search

    Didier Robert

    2007-01-01

    Currently, TiO2 is the most popular semi-conductor used in heterogeneous photocatalysis processes. Upon irradiation, conduction band electrons and valence band holes will be created in the relevant semi-conductor. These electrons and holes react with dissolved oxygen and\\/or adsorbed hydroxyl ions on the semi-conductor surface. That reaction will then initiate redox in the aqueous medium, resulting in the oxidization of organic

  4. 2,4,5-Trichlorophenol degradation using a novel TiO2-coated biofilm carrier: roles of adsorption, photocatalysis, and biodegradation.

    PubMed

    Li, Guozheng; Park, Seongjun; Kang, Dae-Wook; Krajmalnik-Brown, Rosa; Rittmann, Bruce E

    2011-10-01

    Intimate coupling of photocatalysis and biodegradation (ICPB) offers potential for degrading biorecalcitrant and toxic organic compounds. This study reports on a novel sponge-type, TiO(2)-coated biofilm carrier that showed significant adherence of TiO(2) and ability to accumulate biomass in its interior. This carrier was tested for ICPB in a continuous-flow photocatalytic circulating-bed biofilm reactor (PCBBR) to mineralize 2,4,5-trichlorophenol (TCP), which is biorecalcitrant. Four mechanisms possibly acting in ICPB were tested separately: TCP adsorption to the carrier, UV photolysis, UV photocatalysis, and biodegradation by biofilm inside the carrier. The carrier exhibited strong TCP adsorption that followed a Freundlich isotherm with an exponent near 2. Whereas UV photolysis was negligible, photocatalysis produced TCP-degradation products that could be mineralized, and the strong adsorption of TCP to the carrier enhanced biodegradation by relieving toxicity. Validating the ICPB concept, biofilm was protected inside the carriers, although biomass originally on the outer surface of the carriers was eliminated. ICPB significantly lowered the diversity of the bacterial community, but five genera known to biodegrade chlorinated phenols (Ralstonia, Bradyrhizobium, Methylobacterium, Cupriavidus, and Pandoraea) were markedly enriched. PMID:21861477

  5. The Electrodeless Discharge Lamps Coated with the Titania Thin Film for Photocatalysis in a Microwave Field

    E-print Network

    Cirkva, Vladimir

    photochemical and photocatalytic reactions for degradation of organic pollutants. The electrodeless discharge.005 0.010 0.015 0.020 0.025 air bubbling without bubbling Air bubbling wavelength (nm) 200 300 400 500 was thoroughly cleaned in water-soap mixture, distilled water, aqueous hydrofluoric acid and ethanol. 2.5 µl Hg

  6. Activation energies in semiconductor photocatalysis for water purification: the 4-chlorophenol-TiO 2?O 2 photosystem

    Microsoft Academic Search

    Andrew Mills; Richard Davies

    1995-01-01

    The variation in the activation energy for the initial stage of photomineralization of 4-chlorophenol (4-CP), sensitized by Degussa P25 TiO2, was investigated as a function of Po2 and [4-CP]. A model was developed based on the incorporation of Arrhenius-type functions in a general rate equation for the initial stage of photomineralization. Values of the essential constants in the model were

  7. DOE Laboratory Catalysis Research Symposium - Abstracts

    SciTech Connect

    Dunham, T.

    1999-02-01

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

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

    NASA Technical Reports Server (NTRS)

    Underwood, Lauren W.; Ryan, Robert E.

    2007-01-01

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

  9. Correlation between band alignment and enhanced photocatalysis: a case study with anatase/TiO2(B) nanotube heterojunction.

    PubMed

    Wang, Changhua; Zhang, Xintong; Wei, Yongan; Kong, Lina; Chang, Feng; Zheng, Han; Wu, Liangzhuan; Zhi, Jinfang; Liu, Yichun

    2015-07-14

    It has long been known that efficient interfacial charge transfer between different phases of TiO2 is beneficial for enhanced photocatalysis. However, there has been considerable debate over the direction of the charge transfer across the interface of the different TiO2 phases. In this work, we study the case of TiO2 with a novel anatase/TiO2(B) heterojunction (ABHJ), wherein charge carrier transfer across the heterojunction interface is intensively investigated. The ABHJ is prepared by a two-step alkaline hydrothermal route and features nanotubes with a large surface area. Comprehensive analysis including UV-Vis-DRS, XPS, Mott-Schottky measurements, EPR and transient photovoltage techniques provides evidence for a type II band alignment in the ABHJ and migration of the photogenerated electrons from anatase to TiO2(B), which could effectively inhibit the recombination rate of photo-induced electron-hole pairs. Photocatalytic tests demonstrate that the as-obtained ABHJ shows higher activity than both the single phase and P25, not only for hydrogen production, but also for the photodegradation of gaseous acetaldehyde, which is due to the synergistic effect between an efficient charge separation at the interface and a high surface area. PMID:26131909

  10. In situ synthesis of TiO2/SnOx-Au ternary heterostructures effectively promoting visible-light photocatalysis.

    PubMed

    Dong, Zhao; Wu, Minghua; Wu, Jiaying; Ma, Yuanyuan; Ma, Zhenzhen

    2015-07-14

    TiO2/SnOx-Au ternary heterostructures were successfully fabricated via a simple in situ reduction of AuCl4(-) on TiO2 surfaces pre-modified with Sn(2+). The samples were characterized by XRD, TEM, XPS, N2 physical absorption and UV-vis diffuse reflectance spectra. Photocatalytic activity toward degradation of methylene blue (MB) aqueous solution under visible light irradiation was investigated. The results suggested that the highly dispersive and ultrafine Au nanoparticles (NPs) covered with SnOx were deposited onto the surface of TiO2. The heterostructures significantly enhanced the photocatalytic activity compared with the traditional TiO2/Au sample prepared by the impregnation method and also enhanced the activity more than the binary TiO2/SnOx sample. Moreover, the size of the Au NPs could be well controlled by simply tuning the dosage of HAuCl4, and the optimized catalytic activity of the ternary heterostructures was obtained when the dosage of Au was 1% and the Au particle size was ?2.65 nm. The enhancement of photocatalytic performance could be attributed to the surface plasmon resonance effect of the Au NPs and the electron-sink function of the SnOx, which improve the optical absorption properties as well as photoinduced charge carrier separation, synergistically facilitating the photocatalysis. PMID:26061220

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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.

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

    PubMed

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

    2014-03-28

    We have demonstrated a novel method to enhance TiO? 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/TiO? composite photocatalyst is ten times faster than that on a TiO? photocatalyst and three times faster than that on a Ag/TiO? 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/TiO? 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 TiO? to the metallic surface, since any electron transfer will suppress the excitation of SP modes in the metal nanoparticles. PMID:24572147

  13. Solar photo-Fenton using peroxymonosulfate for organic micropollutants removal from domestic wastewater: comparison with heterogeneous TiO? photocatalysis.

    PubMed

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

    2014-12-01

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

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

    PubMed

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

    2014-08-01

    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

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

    Microsoft Academic Search

    Weimin XI; Sven-uwe Geissen

    2001-01-01

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

  16. Water

    MedlinePLUS

    You might not give much thought to water or how it gets to you. You just turn on the faucet and there it is. Do you ever wonder how it flows ... concern that it might make you sick. Your water can come from a lake, a river, a ...

  17. Bio-inspired synthesis of Y2O3: Eu3+ red nanophosphor for eco-friendly photocatalysis

    NASA Astrophysics Data System (ADS)

    Prasanna kumar, J. B.; Ramgopal, G.; Vidya, Y. S.; Anantharaju, K. S.; Daruka Prasad, B.; Sharma, S. C.; Prashantha, S. C.; Premkumar, H. B.; Nagabhushana, H.

    2015-04-01

    We report the synthesis of Y2O3: Eu3+ (1-11 mol%) nanoparticles (NPs) with different morphologies via eco-friendly, inexpensive and simple low temperature solution combustion method using Aloe Vera gel as fuel. The formation of different morphologies of Y2O3: Eu3+ NPs were characterized by PXRD, SEM, TEM, HRTEM, UV-Visible and PL techniques. The PXRD data and Rietveld analysis confirms the formation of single phase Y2O3 with cubic crystal structure. The influence of Eu3+ ion concentration on the morphology, UV-Visible absorption, PL emission and photocatalytic activity of Y2O3: Eu3+ nanostructures were investigated. Y2O3: Eu3+ NPs exhibit intense red emission with CIE chromaticity coordinates (0.50, 0.47) and correlated color temperature values at different excitation ranges from 1868 to 2600 K. The control of Eu3+ ion on Y2O3 matrix influences the photocatalytic decolorization of methylene blue (MB) as a model compound was evaluated under UVA light. Enhanced photocatalytic activity of conical shaped Y2O3: Eu3+ (1 mol%) was attributed to dopant concentration, crystallite size, textural properties and capability of reducing the electron-hole pair recombination. The trend of inhibitory effect in the presence of different radical scavengers followed the order SO42- > Cl- > C2H5OH > HCO3- > CO32-. These findings show great promise of Y2O3: Eu3+ NPs as a red phosphor in warm white LEDs as well as eco-friendly heterogeneous photocatalysis.

  18. Graphene oxide/?-Bi(2)O(3) composites for visible-light photocatalysis, chemical catalysis, and solar energy conversion.

    PubMed

    Som, Tirtha; Troppenz, Gerald V; Wendt, R Robert; Wollgarten, Markus; Rappich, Jörg; Emmerling, Franziska; Rademann, Klaus

    2014-03-01

    The growing challenges of environmental purification by solar photocatalysis, precious-metal-free catalysis, and photocurrent generation in photovoltaic cells receive the utmost global attention. Here we demonstrate a one-pot, green chemical synthesis of a new stable heterostructured, ecofriendly, multifunctional microcomposite that consists of ?-Bi2 O3 microneedles intercalated with anchored graphene oxide (GO) microsheets (1.0?wt?%) for the above-mentioned applications on a large economical scale. The bare ?-Bi2 O3 microneedles display two times better photocatalytic activities than commercial TiO2 (Degussa-P25), whereas the GO-hybridized composite exhibits approximately four to six times enhanced photocatalytic activities than the neat TiO2 photocatalyst in the degradation of colored aromatic organic dyes (crystal violet and rhodamine 6G) under visible-light irradiation (300?W tungsten lamp). The highly efficient activity is associated with the strong surface adsorption ability of GO for aromatic dye molecules, the high carrier acceptability, and the efficient electron-hole pair separation in Bi2 O3 by individual adjoining GO sheets. The introduction of Ag nanoparticles (2.0?wt?%) further enhances the photocatalytic performance of the composite over eightfold because of a plasmon-induced electron-transfer process from Ag nanoparticles through the GO sheets into the conduction band of Bi2 O3 . The new composites are also catalytically active and catalyze the reduction of 4-nitrophenol to 4-aminophenol in the presence of borohydride ions. Photoanodes assembled from GO/?-Bi2 O3 and Ag/GO/?-Bi2 O3 composites display an improved photocurrent response (power conversion efficiency ?20?% higher) over those prepared without GO in dye-sensitized solar cells. PMID:24578169

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

    SciTech Connect

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

    2011-03-15

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

  20. Solar photo-inactivation of phytopathogens by trace level hydrogen peroxide and titanium dioxide photocatalysis

    Microsoft Academic Search

    L. Muszkat; L. Feigelson; L. Bir; K. A. Muszkat; M. Teitel; I. Dornay; B. Kirchner; G. Kirtzman

    2005-01-01

    Plant pathogenic bacteria in recirculated greenhouse water were inactivated by two distinct photochemical approaches: photo-inactivation\\u000a in the presence of 0.005% to 0.01% hydrogen peroxide (H2O2), and photocatalytic inactivation with 0.01% titanium dioxide (TiO2). In both processes photo-inactivation is achieved by exposure to sunlight. Total inactivation, with 6–8 log units decrease\\u000a in viable counts, was achieved in the study of the

  1. Degradation, mineralization and antibiotic inactivation of amoxicillin by UV-A/TiO? photocatalysis.

    PubMed

    Dimitrakopoulou, Despina; Rethemiotaki, Irene; Frontistis, Zacharias; Xekoukoulotakis, Nikolaos P; Venieri, Danae; Mantzavinos, Dionissios

    2012-05-15

    The UV-A/TiO(2) photocatalytic decomposition of amoxicillin (AMX) in aqueous suspensions was investigated. Experiments were performed at antibiotic concentrations between 2.5 and 30 mg/L, eight commercially available TiO(2) catalysts at loadings between 100 and 750 mg/L, acidic or near-neutral conditions (pH 5 or 7.5) and two different matrices (ultrapure water and secondary treated effluent) at a photon flux of 8 × 10(-4) E/(L min). Of the various catalysts tested, Degussa P25 was highly active, i.e. complete AMX degradation and 93% mineralization could be achieved after 25 and 90 min of reaction, respectively at 10 mg/L AMX and 250 mg/L titania. In general, mineralization was slower than degradation due to the formation of stable transformation by-products. For the range of concentrations studied, initial degradation rates can be approached by a Langmuir-Hinshelwood kinetic model, while the reaction order with respect to AMX shifts from first to zeroth as initial concentration increases from 2.5 to 5 mg/L to higher values. Degradation in treated effluent was partly impeded compared to pure water due to the inherent presence of organic and inorganic constituents that compete for hydroxyl radicals. Although increasing solution pH from 5 to 7.5 had no effect on degradation, it retarded mineralization. The antibiotic activity of AMX prior to and after photocatalytic degradation was tested to three reference bacterial strains, namely Escherichia coli (ATCC 23716), Klebsiella pneumoniae (NCTC 5056) and Enterococcus faecalis (ATCC 14506). The first two were found to be highly resistant at AMX concentrations up to 25 mg/L, while the latter could partly be inactivated at lower AMX concentrations (i.e. 10 mg/L) and/or in the presence of photocatalytic by-products. PMID:22277347

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

    PubMed

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

    2015-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

    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.

  4. Formation of hydrogen peroxide and degradation of phenol in synergistic system of pulsed corona discharge combined with TiO2 photocatalysis.

    PubMed

    Wang, Huijuan; Li, Jie; Quan, Xie; Wu, Yan; Li, Guofeng; Wang, Fangzheng

    2007-03-01

    In the present work, a synergistic system of pulsed corona discharge combined with TiO(2) photocatalysis has been developed to investigate the degradation rate of phenol solutions by varying experimental conditions of gas bubbling varieties (air, O(2), and Ar), solution pH values, and radical scavenger additives. The hydrogen peroxide (H(2)O(2)) concentration, which indicated the amount of hydroxyl radicals (OH) in the reaction system under different conditions of gas bubbling varieties and scavenger species, was also reviewed. The obtained results revealed that degradation efficiency of phenol could be increased by the addition of TiO(2) in pulsed discharge system. The gas of Ar and O(2) bubbled into the reaction system was found to be favorable for phenol degradation and H(2)O(2) formation. Both in air bubbling and in O(2) bubbling reaction system, the higher degradation rate of phenol occurred in the case of acidic solution. The addition of sodium carbonate or n-butanol in the solution displayed a negative effect for phenol removal, while the H(2)O(2) concentration showed different changing trend by adding different radical scavengers. The most effective degradation of the three main intermediates of catechol, 1,4-hydroquinone, and 1,4-benzoquinone formed during phenol decomposition existed in the synergistic system of pulsed corona discharge and TiO(2) photocatalysis bubbled with O(2). PMID:16920259

  5. The feasibility of using combined TiO2 photocatalysis oxidation and MBBR process for advanced treatment of biologically pretreated coal gasification wastewater.

    PubMed

    Xu, Peng; Han, Hongjun; Hou, Baolin; Zhuang, Haifeng; Jia, Shengyong; Wang, Dexin; Li, Kun; Zhao, Qian

    2015-08-01

    The study examined the feasibility of using combined heterogeneous photocatalysis oxidation (HPO) and moving bed biofilm reactor (MBBR) process for advanced treatment of biologically pretreated coal gasification wastewater (CGW). The results indicated that the TOC removal efficiency was significantly improved in HPO. Gas chromatography-mass spectrometry (GC-MS) analysis indicated that the HPO could be employed to eliminate bio-refractory and toxic compounds. Meanwhile, the BOD5/COD of the raw wastewater was increased from 0.08 to 0.49. Furthermore, in the integration of TiO2 photocatalysis oxidation and MBBR process, the effluent of COD, BOD5, TOC, NH4(+)-N and TN were 22.1 mg/L, 1.1 mg/L, 11.8 mg/L, 4.1mg/L and 13.7 mg/L, respectively, which all met class-I criteria of the Integrated Wastewater Discharge Standard (GB18918-2002, China). The total operating cost was 2.8CNY/t. Therefore, there is great potential for the combined system in engineering applications as a final treatment for biologically pretreated CGW. PMID:25934578

  6. Remediation of 17-?-ethinylestradiol aqueous solution by photocatalysis and electrochemically-assisted photocatalysis using TiO2 and TiO2/WO3 electrodes irradiated by a solar simulator.

    PubMed

    Oliveira, Haroldo G; Ferreira, Leticia H; Bertazzoli, Rodnei; Longo, Claudia

    2015-04-01

    TiO2 and TiO2/WO3 electrodes, irradiated by a solar simulator in configurations for heterogeneous photocatalysis (HP) and electrochemically-assisted HP (EHP), were used to remediate aqueous solutions containing 10 mg L(-1) (34 ?mol L(-1)) of 17-?-ethinylestradiol (EE2), active component of most oral contraceptives. The photocatalysts consisted of 4.5 ?m thick porous films of TiO2 and TiO2/WO3 (molar ratio W/Ti of 12%) deposited on transparent electrodes from aqueous suspensions of TiO2 particles and WO3 precursors, followed by thermal treatment at 450 (°)C. First, an energy diagram was organized with photoelectrochemical and UV-Vis absorption spectroscopy data and revealed that EE2 could be directly oxidized by the photogenerated holes at the semiconductor surfaces, considering the relative HOMO level for EE2 and the semiconductor valence band edges. Also, for the irradiated hybrid photocatalyst, electrons in TiO2 should be transferred to WO3 conduction band, while holes move toward TiO2 valence band, improving charge separation. The remediated EE2 solutions were analyzed by fluorescence, HPLC and total organic carbon measurements. As expected from the energy diagram, both photocatalysts promoted the EE2 oxidation in HP configuration; after 4 h, the EE2 concentration decayed to 6.2 mg L(-1) (35% of EE2 removal) with irradiated TiO2 while TiO2/WO3 electrode resulted in 45% EE2 removal. A higher performance was achieved in EHP systems, when a Pt wire was introduced as a counter-electrode and the photoelectrodes were biased at +0.7 V; then, the EE2 removal corresponded to 48 and 54% for the TiO2 and TiO2/WO3, respectively. The hybrid TiO2/WO3, when compared to TiO2 electrode, exhibited enhanced sunlight harvesting and improved separation of photogenerated charge carriers, resulting in higher performance for removing this contaminant of emerging concern from aqueous solution. PMID:25238917

  7. Fe doped TiO2-graphene nanostructures: synthesis, DFT modeling and photocatalysis.

    PubMed

    Farhangi, Nasrin; Ayissi, Serge; Charpentier, Paul A

    2014-08-01

    In this work, Fe-doped TiO(2) nanoparticles ranging from a 0.2 to 1 weight % were grown from the surface of graphene sheet templates containing -COOH functionalities using sol-gel chemistry in a green solvent, a mixture of water/ethanol. The assemblies were characterized by a variety of analytical techniques, with the coordination mechanism examined theoretically using the density functional theory (DFT). Scanning electron microscopy and transmission electron microscopy images showed excellent decoration of the Fe-doped TiO(2) nanoparticles on the surface of the graphene sheets >5 nm in diameter. The surface area and optical properties of the Fe-doped photocatalysts were measured by BET, UV and PL spectrometry and compared to non-graphene and pure TiO(2) analogs, showing a plateau at 0.6% Fe. Interactions between graphene and Fe-doped anatase TiO(2) were also studied theoretically using the Vienna ab initio Simulation Package based on DFT. Our first-principles theoretical investigations validated the experimental findings, showing the strength in the physical and chemical adsorption between the graphene and Fe-doped TiO(2). The resulting assemblies were tested for photodegradation under visible light using 17?-estradiol (E2) as a model compound, with all investigated catalysts showing significant enhancements in photocatalytic activity in the degradation of E2. PMID:25002220

  8. Fe doped TiO2-graphene nanostructures: synthesis, DFT modeling and photocatalysis

    NASA Astrophysics Data System (ADS)

    Farhangi, Nasrin; Ayissi, Serge; Charpentier, Paul A.

    2014-08-01

    In this work, Fe-doped TiO2 nanoparticles ranging from a 0.2 to 1 weight % were grown from the surface of graphene sheet templates containing -COOH functionalities using sol-gel chemistry in a green solvent, a mixture of water/ethanol. The assemblies were characterized by a variety of analytical techniques, with the coordination mechanism examined theoretically using the density functional theory (DFT). Scanning electron microscopy and transmission electron microscopy images showed excellent decoration of the Fe-doped TiO2 nanoparticles on the surface of the graphene sheets >5 nm in diameter. The surface area and optical properties of the Fe-doped photocatalysts were measured by BET, UV and PL spectrometry and compared to non-graphene and pure TiO2 analogs, showing a plateau at 0.6% Fe. Interactions between graphene and Fe-doped anatase TiO2 were also studied theoretically using the Vienna ab initio Simulation Package based on DFT. Our first-principles theoretical investigations validated the experimental findings, showing the strength in the physical and chemical adsorption between the graphene and Fe-doped TiO2. The resulting assemblies were tested for photodegradation under visible light using 17?-estradiol (E2) as a model compound, with all investigated catalysts showing significant enhancements in photocatalytic activity in the degradation of E2.

  9. Carbon functionalized TiO2 nanofibers for high efficiency photocatalysis

    NASA Astrophysics Data System (ADS)

    Raghava Reddy, Kakarla; Gomes, Vincent G.; Hassan, Mahbub

    2014-03-01

    TiO2 nanofibers (30-50 nm diameter), fabricated by the electro-spinning process, were modified with organo-silane agents via a coupling reaction and were grafted with carbohydrate molecules. The mixture was carbonized to produce a uniform coating of amorphous carbon on the surface of the TiO2 nanofibers. The TiO2@C nanofibers were characterized by high resolution electron microscopy (HRTEM), x-ray diffraction (XRD), x-ray photoelectron (XPS), Fourier transform infrared (FTIR) and UV-vis spectroscopy. The photocatalytic property of the functional TiO2 and carbon nanocomposite was tested via the decomposition of an organic pollutant. The catalytic activity of the covalently functionalized nanocomposite was found to be significantly enhanced in comparison to unfunctionalized composite and pristine TiO2 due to the synergistic effect of nanostructured TiO2 and amorphous carbon bound via covalent bonds. The improvement in performance is due to bandgap modification in the 1D co-axial nanostructure where the anatase phase is bound by nano-carbon, providing a large surface to volume ratio within a confined space. The superior photocatalytic performance and recyclability of 1D TiO2@C nanofiber composites for water purification were established through dye degradation experiments.

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

    SciTech Connect

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

    2012-11-15

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

  11. Electrocatalysis of oxygen reduction at poly (4-amino-3-hydroxynaphthalene sulfonic acid) and platinum loaded polymer modified glassy carbon electrodes

    NASA Astrophysics Data System (ADS)

    Zewde, Berhanu W.; Admassie, Shimelis

    2012-10-01

    The electrochemical polymerization of p-(4-amino-3-hydroxynaphtalene sulfonic acid) is investigated by using cyclic voltammetry. Low amount of platinum is loaded (17-303 ?g) on the polymer modified glassy carbon electrode. The electrocatalytic activity of the modified electrodes towards oxygen reduction reaction is investigated. The polymer modified glassy carbon electrode shows a two electron reduction of oxygen to hydrogen peroxide and the platinum loaded polymer modified glassy carbon electrode shows a direct four electron reduction of oxygen to water. The chronocoulometric study of the oxygen reduction reaction shows similar results to those obtained with other techniques. Koutecky-Levich plot analysis is used to predict the mechanism and evaluate the kinetic parameters. Temkin adsorption isotherm is observed for lower platinum loading and Langmuirian for high platinum loading.

  12. Simple electro-assisted immobilization of ciprofloxacin on carbon nanotube modified electrodes: its selective hydrogen peroxide electrocatalysis.

    PubMed

    Sornambikai, Sundaram; Kumar, Annamalai Senthil

    2014-09-01

    Ciprofloxacin (Cf) is a synthetic fourth generation fluoroquinolone class antibiotic used for the treatment of gram-positive, gram-negative and mycobacterium species infections. Electrochemical characteristic of the Cf antibiotic on carbon nanotube modified glassy carbon electrode (GCE/CNT) in pH 7 phosphate buffer solution has been investigated. Electrochemically oxidized radical byproduct of the Cf drug, which is formed as intermediate, gets immobilized on the GCE/CNT (GCE/Cf@CNT) and showed stable and well defined surface confined redox peak at -0.220 V versus Ag/AgCl. Control electrochemical experiment with unmodified GCE failed to show any such immobilization and redox features. Physicochemical characterizations of the Cf@CNT by transmission electron microscope, scanning electron microscope, infrared spectroscopy, UV-Vis and gas chromatography coupled mass spectroscopic analyses of Cf@CNT collectively revealed presence of native form of the Cf antibiotic molecule onto the CNT. The interaction between the Cf molecule and the CNT tubes are revealed from the decreased intensity in the Raman spectrum. The GCE/Cf@CNT showed excellent electrocatalytic response to hydrogen peroxide reduction reaction in pH 7 phosphate buffer solution. Amperometric i-t analysis for the detection of H2O2 showed a current linearity plot upto [H2O2] = 200 ?M at an applied potential - 0.1 V versus Ag/AgCl with a current sensitivity value 678 ?A mM(-1) cm(-2). No interferences were noticed with ascorbic acid, uric acid, cysteine and nitrite. The present study can be highly helpful to understand the interaction between the Cf and H2O2 in physiological systems and for the removal of Cf from the antibiotic polluted water samples especially in the aquaculture and agricultural systems. PMID:25924302

  13. Self-etching reconstruction of hierarchically mesoporous F-TiO2 hollow microspherical photocatalyst for concurrent membrane water purifications.

    PubMed

    Pan, Jia Hong; Zhang, Xiwang; Du, Alan Jianhong; Sun, Darren D; Leckie, James O

    2008-08-27

    We report a large-scale self-etching approach for the synthesis of monodispersed mesoporous F-TiO2 hollow microspheres. The self-etching derived from HF was elucidated by the morphology, chemical composition, and crystal size evolutions from solid to hollow microspheres with the increase in the concentration of H2SO4. The resulting TiO2 hollow microspheres exhibited ease for the concurrent membrane filtration and photocatalysis, providing high potential for engineering application in advanced water treatment, for not only increasing water production but also improving water quality. PMID:18680296

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

    PubMed

    Franke, R; Franke, C

    1999-12-01

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

  15. Combination of heterogeneous Fenton-like reaction and photocatalysis using Co-TiO?nanocatalyst for activation of KHSO? with visible light irradiation at ambient conditions.

    PubMed

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

    2014-12-01

    A novel coupled system using Co-TiO?was successfully designed which combined two different heterogeneous advanced oxidation processes, sulfate radical based Fenton-like reaction (SR-Fenton) and visible light photocatalysis (Vis-Photo), for degradation of organic contaminants. The synergistic effect of SR-Fenton and Vis-Photo was observed through comparative tests of 50mg/L Rhodamine B (RhB) degradation and TOC removal. The Rhodamine B degradation rate and TOC removal were 100% and 68.1% using the SR-Fenton/Vis-Photo combined process under ambient conditions, respectively. Moreover, based on XRD, XPS and UV-DRS characterization, it can be deduced that tricobalt tetroxide located on the surface of the catalyst is the SR-Fenton active site, and cobalt ion implanted in the TiO?lattice is the reason for the visible light photocatalytic activity of Co-TiO?. Finally, the effects of the calcination temperature and cobalt concentration on the synergistic performance were also investigated and a possible mechanism for the synergistic system was proposed. This coupled system exhibited excellent catalytic stability and reusability, and almost no dissolution of Co²? was found. PMID:25499492

  16. 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)

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

    2013-09-01

    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.

  17. Controllable fabrication of immobilized ternary CdS/Pt-TiO2 heteronanostructures toward high-performance visible-light driven photocatalysis.

    PubMed

    Gao, Huazhen; Wang, Honge; Jin, Youlai; Lv, Jun; Xu, Guangqing; Wang, Dongmei; Zhang, Xinyi; Chen, Zhong; Zheng, Zhixiang; Wu, Yucheng

    2015-07-21

    Immobilized TiO2 nanotube arrays (NTAs) co-modified with Pt and CdS nanoparticles were fabricated by using the combination of photoreduction and chemical bath deposition methods. XRD, SEM, TEM, XPS, UV-Vis and EDX methods were employed to characterize the microstructure and composition of samples, and the results showed that CdS and Pt NPs were uniformly deposited on the surface of TiO2 nanotubes. The CdS/Pt/TiO2 NTAs exhibited a much higher photocatalytic activity compared to pure TiO2 NTAs and binary CdS (or Pt)/TiO2 NTAs under visible light irradiation. A kinetic study showed that the rate constants of Pt/TiO2, CdS/TiO2 and CdS/Pt/TiO2 NTAs are 0.00736, 0.01717 and 0.02077 min(-1), respectively, revealing a remarkable kinetic enhancement in the ternary heteronanostructures due to the synergistic effect of the three components. Besides, the CdS/Pt/TiO2 NTAs exhibit high stability after being used 22 times. Thus we proposed that such ternary heteronanostructures show great promise as immobilized catalysts for high efficient visible-light-driven photocatalysis. PMID:26085466

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

    PubMed

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

    2014-01-01

    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

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

    SciTech Connect

    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

    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.

  20. Treatment of gasoline-contaminated waters by advanced oxidation processes.

    PubMed

    Tiburtius, Elaine Regina Lopes; Peralta-Zamora, Patricio; Emmel, Alexandre

    2005-11-11

    In this study, the efficiency of advanced oxidative processes (AOPs) was investigated toward the degradation of aqueous solutions containing benzene, toluene and xylenes (BTX) and gasoline-contaminated waters. The results indicated that BTX can be effectively oxidized by near UV-assisted photo-Fenton process. The treatment permits almost total degradation of BTX and removal of more than 80% of the phenolic intermediates at reaction times of about 30 min. Preliminary investigations using water contaminated by gasoline suggest a good potentiality of the process for the treatment of large volumes of aqueous samples containing these polluting species. Heterogeneous photocatalysis and H2O2/UV system show lower degradation efficiency, probably due to the heterogeneous character of the TiO2-mediated system and lost of photonic efficiency of the H2O2/UV system in the presence of highly colored intermediated. PMID:16051429

  1. Destruction of trace organics in otherwise ultra pure water

    SciTech Connect

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

    1995-12-01

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

  2. Destruction of Trace Organics in Otherwise Ultra Pure Water

    SciTech Connect

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

    1995-12-01

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

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

    PubMed

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

    2013-03-01

    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

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

    PubMed

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

    2014-04-15

    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

  5. A novel copper(II) complex constructed with mixed ligands of biphenyl-4,4'-dicarboxylic acid (H 2bpdc) and dipyrido[3,2-d:2',3'-f]quinoxaline (Dpq): Synthesis, structure, electrochemistry and electrocatalysis

    NASA Astrophysics Data System (ADS)

    Lin, HongYan; Wang, XiuLi; Hu, HaiLiang; Chen, BaoKuan; Liu, GuoCheng

    2009-03-01

    A novel metal-organic framework [Cu 2(bpdc) 2(Dpq) 2(H 2O)]·H 2O ( 1) has been obtained from hydrothermal reaction of copper chloride with the mixed ligands [biphenyl-4,4'-dicarboxylic acid (H 2bpdc) and dipyrido[3,2-d:2',3'-f]quinoxaline (Dpq)], and structurally characterized by elemental analysis, IR, TG and single-crystal X-ray diffraction analysis. The unique feature is that there simultaneously exist two kinds of one-dimensional (1-D) zigzag polymeric chains in complex 1. Moreover, the 1-D polymeric chains are ultimately packed into a three-dimensional (3-D) supramolecular framework through two different hydrogen bonding interactions. The adjacent different chains are linked by C-H⋯O hydrogen bonding interactions, and the same kind chains are further connected through C-H⋯? stacking interactions. Additionally, the complex 1 was used as solid bulk-modifier to fabricate renewable carbon paste electrode (Cu-CPE) by the direct mixing method. The electrochemical behavior and electrocatalysis of Cu-CPE have been studied in detail. The results indicate that Cu-CPE give one-electron quasi-reversible redox waves in potential range of 400 to -300 mV due to the metal copper ion Cu(II)/Cu(I). The Cu-CPE showed good electrocatalytic activity toward the reduction of the bromate, nitrite and hydrogen peroxide. The electrocatalytic reduction peak currents of KBrO 3, KNO 2 and H 2O 2 showed a linear dependence on their concentrations. All of the results revealed that the Cu-CPE had a good reproducibility, remarkable long-term stability and especially good surface renewability by simple mechanical polishing in the event of surface fouling, which is important for practical application.

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

    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.

  7. Polydopamine-Coated Porous Substrates as a Platform for Mineralized ?-FeOOH Nanorods with Photocatalysis under Sunlight.

    PubMed

    Zhang, Chao; Yang, Hao-Cheng; Wan, Ling-Shu; Liang, Hong-Qing; Li, Hanying; Xu, Zhi-Kang

    2015-06-01

    Immobilization of photo-Fenton catalysts on porous materials is crucial to the efficiency and stability for water purification. Here we report polydopamine (PDA)-coated porous substrates as a platform for in situ mineralizing ?-FeOOH nanorods with enhanced photocatalytic performance under sunlight. The PDA coating plays multiple roles as an adhesive interface, a medium inducing mineral generation, and an electron transfer layer. The mineralized ?-FeOOH nanorods perfectly wrap various porous substrates and are stable on the substrates that have a PDA coating. The immobilized ?-FeOOH nanorods have been shown to be efficient for degrading dyes in water via a photo-Fenton reaction. The degradation efficiency reaches approximately 100% in 60 min when the reaction was carried out with H2O2 under visible light, and it remains higher than 90% after five cycles. We demonstrate that the PDA coating promotes electron transfer to reduce the electron-hole recombination rate. As a result, the ?-FeOOH nanorods wrapped on the PDA-coated substrates show enhanced photocatalytic performance under direct sunlight in the presence of H2O2. Moreover, this versatile platform using porous materials as the substrate is useful in fabricating ?-FeOOH nanorods-based membrane reactor for wastewater treatment. PMID:25969860

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

    PubMed Central

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

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

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

    PubMed

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

    2012-04-15

    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

  11. Achieving enhanced visible-light-driven photocatalysis using type-II NaNbO3/CdS core/shell heterostructures.

    PubMed

    Kumar, Sandeep; Khanchandani, Sunita; Thirumal, Meganathan; Ganguli, Ashok K

    2014-08-13

    Expanding the light-harvesting range and suppressing the quick recombination of photogenerated charge carriers are of paramount significance in the field of photocatalysis. One possible approach to achieve wide absorption range is to synthesize type-II core/shell heterostructures. In addition, this system also shows great promise for fast separation of charge carriers and low charge recombination rate. Herein, following the surface functionalization method using 3-mercaptopropionic acid (MPA) as a surface functionalizing agent, we report on designing NaNbO3/CdS type-II core/shell heterostructures with an absorption range extending to visible range and explore the opportunity toward degradation of methylene blue (MB) dye as a model pollutant under visible light irradiation. Characterizations including X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), UV-vis diffuse reflectance spectrum (DRS), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), and Raman spectroscopy support the growth of CdS shell onto NaNbO3 nanorods. The resulting core/shell heterostructures unveiled high surface areas, enhanced light harvesting, and appreciably increased photocatalytic activity toward MB degradation compared to individual counterparts and the photocatalytic standard, Degussa P25, under visible light irradiation. The remarkably enhanced photocatalytic activity of core/shell heterostructures could be interpreted in terms of efficient charge separation owing to core/shell morphology and resulting type-II band alignment between NaNbO3 and CdS, which creates a step-like radial potential favoring the localization of one of the carriers in the core and the other in the shell. A plausible mechanism for the degradation of MB dye over NaNbO3/CdS core/shell heterostructures is also elucidated using active species scavenger studies. Our findings imply that hydroxyl radicals (OH(•)) play a crucial role in dictating the degradation of MB under visible light. This work highlights the importance of core/shell heterostructures in leading toward new paradigms for developing highly efficient and reusable photocatalysts for the destructive oxidation of recalcitrant organic pollutants. PMID:25025823

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

    NASA Astrophysics Data System (ADS)

    Obuya, Emilly Akinyi

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

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

    PubMed

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

    2010-02-01

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

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

    PubMed

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

    2014-07-01

    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

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

    SciTech Connect

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

    1999-05-11

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

  16. Water quality Water quantity

    E-print Network

    Boisvert, Jeff

    · Water quality · Water quantity · Remediation strategies MinE 422: Water Resources: Younger, Banwart and Hedin. 2002. Mine Water. Hydrology, Pollution, Remediation. Impacts of mining on water ­ Discharge of untreated waters #12;Impacts of mining on water · Impacts from the mining process

  17. Water quality Water quantity

    E-print Network

    Boisvert, Jeff

    01-1 · Water quality · Water quantity · Remediation strategies MinE 422: Water Resources: Younger, Banwart and Hedin. 2002. Mine Water. Hydrology, Pollution, Remediation. Impacts of mining on water ­ Discharge of untreated waters #12;01-2 Impacts of mining on water · Impacts from the mining process

  18. The photocatalytic disinfection of urban waste waters.

    PubMed

    Herrera Melián, J A; Doña Rodríguez, J M; Viera Suárez, A; Tello Rendón, E; Valdés do Campo, C; Arana, J; Pérez Peña, J

    2000-08-01

    In this paper we present the results of the photocatalytic disinfection of urban waste water. Two microbial groups, total coliforms and Streptococcus faecalis, have been used as indexes to test disinfection efficiencies. Different experimental parameters have been checked, such as the effect of TiO2, solar or UV-lamp light and pH. Disinfection of water samples has been achieved employing both UV-lamp and solar light in agreement with data shown by other authors. The higher disinfection rates obtained employing an UV-lamp may be explained by the stronger incident light intensity. Nevertheless no consistent differences have been found between TiO2-photocatalysis and direct solar or UV-lamp light irradiation at natural sample pH (7.8). At pH 5 the presence of TiO2 increases the relative inactivation rate compared with the absence of the catalyst. After the photocatalytic bacterial inactivation, the later bacterial reappearance was checked for total coliforms at natural pH and pH 5, with and without TiO2. Two h after the photocatalytic treatment, CFU increment was almost nill. But 24 and 48 h later an important bacterial CFU increment was observed. This CFU increment is slower after irradiation with TiO2 at pH 5 in non-air-purged samples. PMID:11057593

  19. Turbid water Clear water

    E-print Network

    Jaffe, Jules

    Turbid water Clear water pixel position cameraresponsecameraresponse pixel position ABSTRACT: A new underwater laser scanning system, providing microbathymetric information in coastal waters is described the backscatter component resulting in enhanced performance in turbid waters. The system is expected to provide

  20. Perovskite oxides: Oxygen electrocatalysis and bulk structure

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

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

    PubMed

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

    2014-10-01

    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

  2. Water, Water Everywhere

    ERIC Educational Resources Information Center

    Keeler, Rusty

    2009-01-01

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

  3. Water Resources Water Quality and Water Treatment

    E-print Network

    Sohoni, Milind

    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

  4. Water, Water Everywhere

    NSDL National Science Digital Library

    NASA

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

  5. Nanocomposite heterojunctions as sunlight-driven photocatalysts for hydrogen production from water splitting

    NASA Astrophysics Data System (ADS)

    Reza Gholipour, Mohammad; Dinh, Cao-Thang; Béland, François; Do, Trong-On

    2015-04-01

    Hydrogen production via photocatalytic water splitting using sunlight has enormous potential in solving the worldwide energy and environmental crisis. The key challenge in this process is to develop efficient photocatalysts which must satisfy several criteria such as high chemical and photochemical stability, effective charge separation and strong sunlight absorption. The combination of different semiconductors to create composite materials offers a promising way to achieve efficient photocatalysts because doing so can improve the charge separation, light absorption and stability of the photocatalysts. In this review article, we summarized the most recent studies on semiconductor composites for hydrogen production under visible light irradiation. After a general introduction about the photocatalysis phenomenon, typical heterojunctions of widely studied heterogeneous semiconductors, including titanium dioxide, cadmium sulfide and graphitic carbon nitride are discussed in detail.

  6. Photocatalyzed destruction of water contaminants

    Microsoft Academic Search

    David F. Ollis; Ezio Pelizzetti; Nick Serpone

    1991-01-01

    Heterogeneous photocatalysis is a process in which the illumination of an oxide semiconductor, usually the anatase form of titanium dioxide, produces photoexcited electrons (e⁻) and holes (h{sup +}). These can migrate to the oxide surface and participate in half-cell reactions that are part of a closed, catalytic cycle. In the aqueous phase, the illuminated surface is widely regarded as a

  7. Plasmon-enhanced water splitting on TiO2-passivated GaP photocatalysts.

    PubMed

    Qiu, Jing; Zeng, Guangtong; Pavaskar, Prathamesh; Li, Zhen; Cronin, Stephen B

    2014-02-21

    Integrating plasmon resonant nanostructures with photocatalytic semiconductors shows great promise for high efficiency photocatalytic water splitting. However, the electrochemical instability of most III-V semiconductors severely limits their applicability in photocatalysis. In this work, we passivate p-type GaP with a thin layer of n-type TiO2 using atomic layer deposition. The TiO2 passivation layer prevents corrosion of the GaP, as evidenced by atomic force microscopy and photoelectrochemical measurements. In addition, the TiO2 passivation layer provides an enhancement in photoconversion efficiency through the formation of a charge separating pn-region. Plasmonic Au nanoparticles deposited on top of the TiO2-passivated GaP further increases the photoconversion efficiency through local field enhancement. These two enhancement mechanisms are separated by systematically varying the thickness of the TiO2 layer. Because of the tradeoff between the quickly decaying plasmonic fields and the formation of the pn-charge separation region, an optimum performance is achieved for a TiO2 thickness of 0.5 nm. Finite difference time domain (FDTD) simulations of the electric field profiles in this photocatalytic heterostructure corroborate these results. The effects of plasmonic enhancement are distinguished from the natural catalytic properties of Au by evaluating similar photocatalytic TiO2/GaP structures with catalytic, non-plasmonic metals (i.e., Pt) instead of Au. This general approach of passivating narrower band gap semiconductors enables a wider range of materials to be considered for plasmon-enhanced photocatalysis for high efficiency water splitting. PMID:24401904

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    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.

  9. Water, Water Everywhere

    NSDL National Science Digital Library

    2012-06-26

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

  10. Water, Water Everywhere! Research the Water Cycle

    NSDL National Science Digital Library

    Regina Bale

    2012-07-17

    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.

  11. Water, water everywhere

    Microsoft Academic Search

    Pennisi

    1993-01-01

    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.

  12. 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)

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

    2014-04-01

    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

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

    PubMed

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

    2014-05-01

    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. PMID:24664127

  14. Drinking Water

    MedlinePLUS

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

  15. UNL WATER CENTER WATER CURRENT

    E-print Network

    Nebraska-Lincoln, University of

    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

  16. UNL WATER CENTER WATER CURRENT

    E-print Network

    Nebraska-Lincoln, University of

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

  17. UNL WATER CENTER WATER CURRENT

    E-print Network

    Nebraska-Lincoln, University of

    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

  18. UNL WATER CENTER WATER CURRENT

    E-print Network

    Nebraska-Lincoln, University of

    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

  19. Water, Water, Everywhere.

    ERIC Educational Resources Information Center

    Selinger, Ben

    1979-01-01

    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)

  20. Water, Water, Everywhere.

    ERIC Educational Resources Information Center

    Fahey, John A.

    2000-01-01

    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)

  1. Synthesis of the MoS2@CuO heterogeneous structure with improved photocatalysis performance and H2O adsorption analysis.

    PubMed

    Li, Honglin; Yu, Ke; Lei, Xiang; Guo, Bangjun; Li, Chao; Fu, Hao; Zhu, Ziqiang

    2015-05-27

    MoS2@CuO heterogeneous structure nanoflowers were synthesized through a two-step hydrothermal method for the first time. The valence band offset (VBO) and conduction band offset (CBO) of the MoS2@CuO heterojunction, and the bases for the design of the heterogeneous structure were determined by X-ray photoemission spectroscopy (XPS). For the increased specific surface area and the formation of staggered type-II band alignment of the composite structure, a significantly enhanced photocatalytic ability of the MoS2@CuO heterojunction was obtained by studying the photodegradation of methylene blue (MB). After irradiation for 100 min, the residual MB in solution was about 27.5% for pristine MoS2 nanoflowers while it was 4.3% for MoS2@CuO hetero-nanoflowers, respectively. The humidity sensing properties of the two nanostructures were also studied for comparison. The results showed that better response/recover times were obtained. In order to give a theoretical explanation for this phenomenon, we performed first-principles calculation to analyse the corresponding humidity sensing mechanisms of MoS2 and MoS2@CuO in detail. The calculated results showed that water molecules could bind stronger to the CuO surface compared to MoS2, which is in line with the experimental observations. PMID:25978695

  2. Water Works.

    ERIC Educational Resources Information Center

    Van De Walle, Carol

    1988-01-01

    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)

  3. 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.

  4. 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

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

    2014-01-01

    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

  5. Water, Water Everywhere!

    ERIC Educational Resources Information Center

    Sible, Kathleen P.

    2000-01-01

    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)

  6. UNL WATER CENTER WATER CURRENT

    E-print Network

    Nebraska-Lincoln, University of

    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

  7. 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

  8. UNL WATER CENTER WATER CURRENT

    E-print Network

    Nebraska-Lincoln, University of

    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

  9. Earth's Water

    NSDL National Science Digital Library

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

  10. Water Conditioner

    NASA Technical Reports Server (NTRS)

    1991-01-01

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

  11. 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.

  12. Water, Water Everywhere, But...

    ERIC Educational Resources Information Center

    Jacobson, Cliff

    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…

  13. Healthy Water

    MedlinePLUS

    ... most precious global resource. Clean and safe drinking water is critical to sustain human life and without it waterborne illness can be a serious problem. Water, which is necessary for recreational water activities like ...

  14. Water Properties

    NSDL National Science Digital Library

    2009-11-04

    This simple description of the chemical and physical properties of water was produced by the U.S. Geological Survey. It includes a brief quiz to assess prior knowledge, diagrams of water molecules, and important numerical data about water.

  15. UNL WATER CENTER WATER CURRENT

    E-print Network

    Nebraska-Lincoln, University of

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

  16. UNL WATER CENTER WATER CURRENT

    E-print Network

    Nebraska-Lincoln, University of

    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

  17. Water Treatment

    NSDL National Science Digital Library

    2013-12-18

    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.

  18. 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.

  19. Water, Water Everywhere

    NSDL National Science Digital Library

    Integrated Teaching and Learning Program,

    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.

  20. Water, Water Everywhere

    NSDL National Science Digital Library

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

  1. Porous SiC nanowire arrays as stable photocatalyst for water splitting under UV irradiation

    SciTech Connect

    Liu, Hailong [Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)] [Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); She, Guangwei, E-mail: shegw@mail.ipc.ac.cn [Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)] [Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Mu, Lixuan [Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)] [Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Shi, Wensheng, E-mail: shiws@mail.ipc.ac.cn [Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)] [Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Arrays of porous SiC nanowires prepared by a facile in situ carbonizing method. Black-Right-Pointing-Pointer Utilizing the SiC nanowire arrays as photocatalysis for water splitting. Black-Right-Pointing-Pointer Excellent photocatalytic performance under the UV irradiation. Black-Right-Pointing-Pointer Very high stability of the SiC nanowire photocatalyst. -- Abstract: In this study, we report the fabrication and photocatalytic properties of the oriented arrays of SiC nanowires on the Si substrate. The SiC nanowire arrays were prepared by carbonizing the Si nanowire arrays with the graphite powder at 1250 Degree-Sign C. The as-prepared SiC nanowires are highly porous, which endows them with a high surface-to-volume ratio. Considering the large surface areas and the high stability, the porous SiC nanowire arrays were used as photocatalyst for water splitting under UV irradiation. It was found that such porous SiC structure exhibited an enhanced and extremely stable photocatalytic performance.

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

    PubMed

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

    2012-06-30

    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

  3. Cobalt-phosphate-assisted photoelectrochemical water oxidation by arrays of molybdenum-doped zinc oxide nanorods.

    PubMed

    Lin, Yan-Gu; Hsu, Yu-Kuei; Chen, Ying-Chu; Lee, Bing-Wei; Hwang, Jih-Shang; Chen, Li-Chyong; Chen, Kuei-Hsien

    2014-09-01

    We report the first demonstration of cobalt phosphate (Co-Pi)-assisted molybdenum-doped zinc oxide nanorods (Zn(1-x)Mo(x)O NRs) as visible-light-sensitive photofunctional electrodes to fundamentally improve the performance of ZnO NRs for photoelectrochemical (PEC) water splitting. A maximum photoconversion efficiency as high as 1.05% was achieved, at a photocurrent density of 1.4?mA?cm(-2). More importantly, in addition to achieve the maximum incident photon to current conversion efficiency (IPCE) value of 86%, it could be noted that the IPCE of Zn(1-x)Mo(x)O photoanodes under monochromatic illumination (450?nm) is up to 12%. Our PEC performances are comparable to those of many oxide-based photoanodes in recent reports. The improvement in photoactivity of PEC water splitting may be attributed to the enhanced visible-light absorption, increased charge-carrier densities, and improved interfacial charge-transfer kinetics due to the combined effect of molybdenum incorporation and Co-Pi modification, contributing to photocatalysis. The new design of constructing highly photoactive Co-Pi-assisted Zn(1-x)Mo(x)O photoanodes enriches knowledge on doping and advances the development of high-efficiency photoelectrodes in the solar-hydrogen field. PMID:25044962

  4. Water Quality

    MedlinePLUS

    What is in that water that you just drank? Is it just hydrogen and oxygen atoms? Is it safe for drinking? All water is of a certain "quality" (and you can't tell by just looking), but what does "water quality" really mean? Water full of dirt and ...

  5. Water Ways

    ERIC Educational Resources Information Center

    Jahrling, Peter

    2007-01-01

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

  6. Ground Water

    NSDL National Science Digital Library

    This United States Geological Survey (USGS) general interest publication presents a description of ground water in the U.S. This includes what ground water is, how it occurs, aquifers and wells, ground water quality and what affects it, and the state of U.S. ground water resources.

  7. Disappearing Water

    NSDL National Science Digital Library

    WGBH Educational Foundation

    2005-01-01

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

  8. WATER QUALITY

    EPA Science Inventory

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

  9. Stacking Water

    NSDL National Science Digital Library

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

  10. Water Conservation

    NSDL National Science Digital Library

    2005-01-01

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

  11. 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.

  12. Water Phases

    NSDL National Science Digital Library

    Every day, we encounter water in its three phases: liquid water, solid ice, and water vapor, an invisible gas. Most other substances can exist in these three phases as well, but water is unique because it is the only substance that can exist in all three phases at Earth's ordinary temperature conditions. This slide show provides examples of water in each of its three phases.

  13. Electrocatalysis of the reduction of dioxygen by adsorbed cobalt 5,10,15,20-tetraarylporphyrins to which one, two, or three Ru(NH[sub 3])[sub 5][sup 2+] centers are coordinated

    SciTech Connect

    Steiger, B.; Chunnian Shi; Anson, F.C. (California Inst. of Technology, Pasadena (United States))

    1993-05-12

    The reactions of Ru(NH[sub 3])[sub 5]OH[sub 2][sup 2+] with the pyridine sites in (5-(4-pyridyl)-10,15,20-triphenylporphyrinato)cobalt(II), (5,10-bis(4-pyridyl)-15,20-diphenylporphyrinato)cobalt(II), (5,10-bis(4-pyridyl)-15,20-bis(4-(trifluoromethyl)phenyl)porphyrinato)cobalt(II), (5,15-bis(4-pyridyl)-10,20-diphenylporphyrinato)cobalt(II), and (5,10,15-tris(4-pyridyl)-20-phenylporphyrinato)cobalt(II) adsorbed on pyrolytic graphite electrodes produce the mono-, di-, and triruthenated complexes. The adsorbed complexes act as catalysts for the reduction of dioxygen. The mono- and diruthenated complexes catalyze the two-electron reduction of dioxygen to hydrogen peroxide, whereas the triruthenated complex catalyzes the four-electron reduction to water. The preparation and electrocatalytic behavior of the catalysts are described. A comparison of the catalysts has provided additional insight into the mechanisms by which they operate in catalyzing the electroreduction of dioxygen. 20 refs., 9 figs., 2 tabs.

  14. 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.

  15. Water tight.

    PubMed

    Postel, S

    1993-01-01

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

  16. Branding water.

    PubMed

    Dolnicar, Sara; Hurlimann, Anna; Grün, Bettina

    2014-06-15

    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

  17. Branding water

    PubMed Central

    Dolnicar, Sara; Hurlimann, Anna; Grün, Bettina

    2014-01-01

    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

  18. Water Safety

    MedlinePLUS

    ... best measure of protection. Back Continue Making Kids Water Wise It's important to teach your kids proper ... the pool is not in use. Back Continue Water Safety Outdoors First, teach kids never to swim ...

  19. Water Filtration

    NSDL National Science Digital Library

    2014-09-18

    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.

  20. Surface Water

    NSDL National Science Digital Library

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

  1. Drinking Water and Ground Water: Kids' Stuff

    MedlinePLUS

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

  2. Special Topics in Water Science (Water Pollution)

    MedlinePLUS

    ... Q&A Teachers Contact Back to previous page Water Basics Earth's Water Where is Earth's water? How much water is ... wet is your state? Glaciers and icecaps Watersheds Water Properties Water properties Adhesion and cohesion Capillary action ...

  3. EXTENSION WATER SUMMIT PRIORITY: WATER CONSERVATION

    E-print Network

    Kane, Andrew S.

    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

  4. Regional Water Management: Adapting to Uncertain Water

    E-print Network

    Nebraska-Lincoln, University of

    Regional Water Management: Adapting to Uncertain Water Supply and Demand Jim Schneider, Ph · Identify the basin goals and concerns · Assess the water supply and water demands · Develop · How Nebraska manages water · Dealing with uncertain water supplies: adaptive management #12;Regional

  5. Water Treatment

    NSDL National Science Digital Library

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

  6. 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.

  7. Water Markets and Water Quality

    Microsoft Academic Search

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

    1993-01-01

    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

  8. Ground Water Ground Sky Sky Water Vegetation Ground Vegetation Water

    E-print Network

    Chen, Tsuhan

    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

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

    NASA Astrophysics Data System (ADS)

    Sayama, K.; Arai, T.

    2008-02-01

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

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

    PubMed Central

    2012-01-01

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

  11. Water Animation

    NSDL National Science Digital Library

    John Kyrk

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

  12. Water Jetting

    NASA Technical Reports Server (NTRS)

    1985-01-01

    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.

  13. Source Water Protection

    MedlinePLUS

    ... Drinking Water Source Water Source Water Protection Source Water Protection The drinking water we receive from our ... communities, resource managers and the public. My Source Water Basic Information Frequent Questions Source Water Pocket Guide ( ...

  14. Water Harvesting

    NSDL National Science Digital Library

    Critchley, Will

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

  15. Water underground

    NASA Astrophysics Data System (ADS)

    de Graaf, Inge

    2015-04-01

    The world's largest assessable source of freshwater is hidden underground, but we do not know what is happening to it yet. In many places of the world groundwater is abstracted at unsustainable rates: more water is used than being recharged, leading to decreasing river discharges and declining groundwater levels. It is predicted that for many regions of the world unsustainable water use will increase, due to increasing human water use under changing climate. It would not be long before shortage causes widespread droughts and the first water war begins. Improving our knowledge about our hidden water is the first step to stop this. The world largest aquifers are mapped, but these maps do not mention how much water they contain or how fast water levels decline. If we can add a third dimension to the aquifer maps, so a thickness, and add geohydrological information we can estimate how much water is stored. Also data on groundwater age and how fast it is refilled is needed to predict the impact of human water use and climate change on the groundwater resource.

  16. Water Exploration

    NSDL National Science Digital Library

    Kathy Kelly Ellins

    2012-01-01

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

  17. Water Filters

    NASA Technical Reports Server (NTRS)

    1993-01-01

    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.

  18. Computerized Waters 

    E-print Network

    Wythe, Kathy

    2006-01-01

    tx H2O | pg. 9 Computerized Waters Story by Kathy Wythe Computerized Waters Model changes management of Texas surface waters In an office on the second floor of a Texas A&MUniversity building, on a desktop computeroperating with the popular... 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...

  19. Photocatalysis and promoted photocatalysis during photocrosslinking of multifunctional acrylates in composite membranes immobilizing titanium dioxide

    Microsoft Academic Search

    Ignazio Renato Bellobono; Roberto Morelli; Claudia Maria Chiodaroli

    1997-01-01

    The photocatalytic activities of semiconductor titanium dioxide (added to a standard titanium dioxide pigment) and five organometallic coordination compounds (containing cobalt(III) and vanadium(V) as central atoms) have been investigated during the photopolymerization and photocrosslinking of acrylic monomers, employed for the preparation of composite membranes by photografting onto a non-woven polyester support. By partly or wholly substituting the 30 wt.% titanium

  20. Water Pollution

    MedlinePLUS

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

  1. Mixing Water

    NSDL National Science Digital Library

    Francis Eberle

    2007-01-01

    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.

  2. Water Filter

    NSDL National Science Digital Library

    WGBH Boston

    2002-01-01

    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.

  3. Water Filters

    NASA Technical Reports Server (NTRS)

    1987-01-01

    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.

  4. Drinking Water

    EPA Science Inventory

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

  5. Microfluidic platforms and fundamental electrocatalysis studies for fuel cell applications

    Microsoft Academic Search

    Jamie Lee Cohen

    2007-01-01

    The fabrication and testing of a planar membraneless microchannel fuel cell, based on a silicon microchannel, is described in detail. Laminar flow of fuel and oxidant streams, one on top of the other, prevents fuel crossover while allowing ionic transport at the interface between the two solutions. By employing laminar flow, the useful functions of a membrane are retained, while

  6. Perovskite-type oxides - Oxygen electrocatalysis and bulk structure

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  7. Redox active iron nitrosyl units in proton reduction electrocatalysis.

    PubMed

    Hsieh, Chung-Hung; Ding, Shengda; Erdem, Özlen F; Crouthers, Danielle J; Liu, Tianbiao; McCrory, Charles C L; Lubitz, Wolfgang; Popescu, Codrina V; Reibenspies, Joseph H; Hall, Michael B; Darensbourg, Marcetta Y

    2014-01-01

    Base metal, molecular catalysts for the fundamental process of conversion of protons and electrons to dihydrogen, remain a substantial synthetic goal related to a sustainable energy future. Here we report a diiron complex with bridging thiolates in the butterfly shape of the 2Fe2S core of the [FeFe]-hydrogenase active site but with nitrosyl rather than carbonyl or cyanide ligands. This binuclear [(NO)Fe(N2S2)Fe(NO)2](+) complex maintains structural integrity in two redox levels; it consists of a (N2S2)Fe(NO) complex (N2S2=N,N'-bis(2-mercaptoethyl)-1,4-diazacycloheptane) that serves as redox active metallodithiolato bidentate ligand to a redox active dinitrosyl iron unit, Fe(NO)2. Experimental and theoretical methods demonstrate the accommodation of redox levels in both components of the complex, each involving electronically versatile nitrosyl ligands. An interplay of orbital mixing between the Fe(NO) and Fe(NO)2 sites and within the iron nitrosyl bonds in each moiety is revealed, accounting for the interactions that facilitate electron uptake, storage and proton reduction. PMID:24785411

  8. Characterizing nano-scale electrocatalysis during partial oxidation of methane

    PubMed Central

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

    2014-01-01

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

  9. Constant chemical potential approach for quantum chemical calculations in electrocatalysis

    PubMed Central

    Schneider, Wolfgang B

    2014-01-01

    Summary 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

  10. Electrocatalysis of fuel cell reactions: Investigation of alternate electrolytes

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    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.

  11. Electrocatalysis of fuel cell reactions: Investigation of alternate electrolytes

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

  12. Microfluidic platforms and fundamental electrocatalysis studies for fuel cell applications

    NASA Astrophysics Data System (ADS)

    Cohen, Jamie Lee

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

  13. Electrochemistry and electrocatalysis with heme proteins in chitosan biopolymer films

    Microsoft Academic Search

    He Huang; Naifei Hu; Yonghuai Zeng; Gu Zhou

    2002-01-01

    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

  14. Ground water. [Water pollution control

    Microsoft Academic Search

    Costle

    1980-01-01

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

  15. Water Purification

    NASA Technical Reports Server (NTRS)

    1994-01-01

    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.

  16. Sinking Water

    NSDL National Science Digital Library

    2012-08-01

    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.

  17. Water Filters

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Seeking to find a more effective method of filtering potable water that was highly contaminated, Mike Pedersen, founder of Western Water International, learned that NASA had conducted extensive research in methods of purifying water on board manned spacecraft. The key is Aquaspace Compound, a proprietary WWI formula that scientifically blends various types of glandular activated charcoal with other active and inert ingredients. Aquaspace systems remove some substances; chlorine, by atomic adsorption, other types of organic chemicals by mechanical filtration and still others by catalytic reaction. Aquaspace filters are finding wide acceptance in industrial, commercial, residential and recreational applications in the U.S. and abroad.

  18. Water Resources Policy & Economics

    E-print Network

    Buehrer, R. Michael

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

  19. Water Privatisation 

    E-print Network

    Zölls, Elisa

    2011-08-17

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

  20. Grabbing Water

    E-print Network

    Reis, Pedro Miguel

    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 ...

  1. 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.

  2. Water resources

    SciTech Connect

    NONE

    1995-10-01

    This section of the Energy Vision 2020 draft report discusses the environmental effects on the water resources of the region. Water quality concerns in the region include: (1) point and non-point sources of pollution, (2) toxic substances found in both sediments and wildlife of some reservoirs, and (3) occurrences of low dissolved oxygen levels downstream of certain dams. Each of these concerns are discussed with respect to the aquatic environments of the region.

  3. Water watch

    Microsoft Academic Search

    Gruber

    1993-01-01

    This issue of [open quotes]Water Watch[close quotes] focuses on summer streamflow. In addition, a summary of streamflow, soil moisture, and water supply conditions through the end of May is presented. In addition, short-term streamflow forecasts are given. Forecasts are based on the National Weather Service US Climate Analysis Center's 90-day outlook. Temperature and precipitation probability estimates given in the outlook

  4. Water Watch

    Microsoft Academic Search

    Gruber

    1993-01-01

    This issue of [open quotes]Water Watch,[close quotes] focusing on streamflow, is based on reports and data provided by the National Weather Service Office of hydrology and River Forecast Centers, US Department of Agriculture, the Bureau of Reclamation, Soil Conservation Service, California Department of Water Resources, and the US Geological Survey. Ninety-day outlooks are through August. For purposes of reporting, the

  5. Filtering Water

    NSDL National Science Digital Library

    Brieske, Joel A.

    2003-01-01

    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.

  6. Water availability, water quality water governance: the future ahead

    NASA Astrophysics Data System (ADS)

    Tundisi, J. G.; Matsumura-Tundisi, T.; Ciminelli, V. S.; Barbosa, F. A.

    2015-04-01

    The major challenge for achieving a sustainable future for water resources and water security is the integration of water availability, water quality and water governance. Water is unevenly distributed on Planet Earth and these disparities are cause of several economic, ecological and social differences in the societies of many countries and regions. As a consequence of human misuse, growth of urbanization and soil degradation, water quality is deteriorating continuously. Key components for the maintenance of water quantity and water quality are the vegetation cover of watersheds, reduction of the demand and new water governance that includes integrated management, predictive evaluation of impacts, and ecosystem services. Future research needs are discussed.

  7. Super-resolution mapping of reactive sites on titania-based nanoparticles with water-soluble fluorogenic probes.

    PubMed

    Tachikawa, Takashi; Yonezawa, Tomoyuki; Majima, Tetsuro

    2013-01-22

    Interfacial charge transfer at the heterogeneous surface of semiconductor nanoparticles is a fundamental process that is relevant to many important applications, such as photocatalysis, solar cells, and sensors. In this study, we developed new water-soluble fluorogenic probes for interfacial electron transfer reactions on semiconductor nanoparticles. The synthesized boron-dipyrromethene-based fluorescence dyes have one or two sulfonate groups, which confer solubility in aqueous media, and a dinitrophenyl group as a redox reaction site. These probes produce the corresponding fluorescent products via multiple interfacial electron transfer processes, allowing us to investigate the photoinduced redox reactions over individual pristine and Au-nanoparticle-deposited TiO(2) nanoparticles at the single-particle, single-molecule levels. The minimum probe concentration to detect single-product molecules on a single TiO(2) nanoparticle was found to be in the nanomolar range (<10 nM) in acidic solution. Furthermore, super-resolution mapping of the reaction sites revealed that visible-light-induced reduction reactions preferentially occurred on the TiO(2) surface within a distance of a few tens of nanometers around the deposited Au nanoparticles. This result was qualitatively interpreted on the basis of plasmon-induced electron and/or energy transfer mechanisms. Overall, this study provides a great deal of valuable information related to solar-energy-conversion processes that is impossible or difficult to obtain from ensemble-averaged experiments. PMID:23215155

  8. 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

  9. Reuse of Regenerated Waters Under Water Scarcity

    Microsoft Academic Search

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

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

  10. Water watch

    SciTech Connect

    Gruber, N.

    1993-06-01

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

  11. Water Conservation and Water Storage

    NASA Astrophysics Data System (ADS)

    Narayanan, M.

    2014-12-01

    Water storage can be a viable part of the solution to water conservation. This means that we should include reservoirs. Regardless, one should evaluate all aspects of water conservation principles. Recent drought in California indicates that there is an urgent need to re-visit the techniques used to maintain the water supply-chain mechanism in the entire state. We all recognize the fact that fish and wildlife depend on the streams, rivers and wetlands for survival. It is a well-known fact that there is an immediate need to provide solid protection to all these resources. Laws and regulations should help meet the needs of natural systems. Farmers may be forced to drilling wells deeper than ever. But, they will be eventually depleting groundwater reserves. Needless to say that birds, fish and wildlife cannot access these groundwater table. California is talking a lot about conservation. Unfortunately, the conservation efforts have not established a strong visible hold. The Environmental Protection Agency has a plan called E2PLAN (Narayanan, 2012). It is EPA's plan for achieving energy and environmental performance, leadership, accountability, and carbon neutrality. In June 2011, the EPA published a comprehensive, multi-year planning document called Strategic Sustainability Performance Plan. The author has previously reported these in detail at the 2012 AGU fall meeting. References: Ziegler, Jay (15 JUNE 2014). The Conversation: Water conservation efforts aren't taking hold, but there are encouraging signs. THE SACRAMENTO BEE. California. Narayanan, Mysore. (2012). The Importance of Water Conservation in the 21st Century. 72nd AGU International Conference. Eos Transactions: American Geophysical Union, Vol. 92, No. 56, Fall Meeting Supplement, 2012. H31I - 1255.http://www.sacbee.com/2014/06/15/6479862/jay-ziegler-water-conservation.html#storylink=cpy

  12. Water watch

    SciTech Connect

    Not Available

    1992-10-01

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

  13. Water Watch

    SciTech Connect

    Gruber, N.

    1993-08-01

    This issue of [open quotes]Water Watch,[close quotes] focusing on streamflow, is based on reports and data provided by the National Weather Service Office of hydrology and River Forecast Centers, US Department of Agriculture, the Bureau of Reclamation, Soil Conservation Service, California Department of Water Resources, and the US Geological Survey. Ninety-day outlooks are through August. For purposes of reporting, the US is divided into six regions. The data presented can be used to observe how weather conditions affected hydro generation in May.

  14. Marketing water 

    E-print Network

    Wythe, Kathy

    2008-01-01

    citizens how to design and care for a garden planted with plants, shrubs, and trees that thrive in the area and need less water. In 2005, SmartScape? expanded to West Texas. In Central Texas, Austin, known for its progressive approach to conserving...://www.takecareoftexas.org/) program in April 2007. In addition to water quality and quantity and air quality, it addresses energy conservation and waste reduction. Stories by Kathy Wythe tx H2O | pg. 19 EARTH#31;KIND promotes environmental stewardship EARTH-KIND, Texas...

  15. Water Spout

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    2013-01-01

    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.…

  16. Grabbing water

    E-print Network

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

    2012-07-16

    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.

  17. Blue Water

    USGS Multimedia Gallery

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

  18. Water Filtration

    ERIC Educational Resources Information Center

    Jacobsen, Erica K.

    2004-01-01

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

  19. Weightless Water

    NSDL National Science Digital Library

    2012-06-26

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

  20. Water watch

    Microsoft Academic Search

    Gruber

    1992-01-01

    This issue of [open quotes]Water Watch[close quotes] focuses on soil moisture and fall streamflow. A map depicts soil moisture conditions in the US through early October. The analysis is based on reports and data provided by the National Weather Service Office of Hydrology, the US Department of Agriculture, the Bureau of Reclamation, the Soil Conservation Service, the California Department of

  1. Water watch

    SciTech Connect

    Gruber, N.

    1993-02-01

    This issue of Water Watch focuses on soil moisture and winter streamflow development, particularly in the western U.S. Ninety-day outlooks are through March 1993. Hydropower generation statistics for the U.S. for December 1991 and '92 and December 10 year average are also provided.

  2. Water watch

    SciTech Connect

    Not Available

    1991-10-01

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

  3. Water watch

    Microsoft Academic Search

    Gruber

    1993-01-01

    This issue of Water Watch focuses on soil moisture and winter streamflow development, particularly in the western U.S. Ninety-day outlooks are through March 1993. Hydropower generation statistics for the U.S. for December 1991 and '92 and December 10 year average are also provided.

  4. Investigating Water 

    E-print Network

    Howard Jr., Ronald A.

    2002-01-02

    substances. It covers most of the earth?s surface, sometimes to a depth of more than a mile. It exists as a colorless gas in the atmosphere. It caps the poles with ice and occurs in the snows of winter. Liquid water fills brooks, streams, rivers, lakes, ponds...

  5. Troubling Waters

    NSDL National Science Digital Library

    Carolyn J. Strange (freelance writer; )

    2008-12-01

    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.

  6. Water Hyacinth

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  7. The Water Cycle

    NSDL National Science Digital Library

    Ms. Andrus

    2007-10-12

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

  8. Arkansas Water Resources Center

    E-print Network

    Soerens, Thomas

    -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

  9. ?eta-carotene protects sudan IV from photocatalytic degradation in a micellar model system: Insights into the antioxidant properties of the “golden” Staphylococcus aureus

    Microsoft Academic Search

    Cristina M. Coates; William Caldwell; Randall S. Alberte; Patricia D. Barreto; Jose C. Barreto

    2007-01-01

    Sterilization using titanium dioxide-mediated photocatalysis has been shown to be a powerful biocidal process due to the production\\u000a of reactive redox species (RRS). More specifically, these RRS generated from TiO2 photocatalysis are able to completely oxidize organic material, including microorganisms. Photocatalysis is a potentially\\u000a useful application for the production of u.v.-illuminated self-sterilizing surfaces such as in surgical suites or water

  10. Water watch

    SciTech Connect

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

    1992-12-01

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

  11. Water Striders

    NSDL National Science Digital Library

    Lawrence Hall of Science

    1981-01-01

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

  12. Water analysis

    SciTech Connect

    MacCarthy, P.; Klusman, R.W.; Rice, J.A.

    1987-06-15

    This is the twenty-second biennial review dealing with the inorganic and organic analytical chemistry of water. The format of this review is essentially the same as that of the previous review in this series which was published in Analytical Chemistry in 1985. The references used in preparing this review were compiled by a computer-search of Chemical Abstracts covering the period from the previous review (September 1984) through October 1986.

  13. Ground water provides drinking water, irrigation for

    E-print Network

    Saldin, Dilano

    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

  14. 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

  15. WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE

    E-print Network

    Nebraska-Lincoln, University of

    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

  16. Water Sustainability Program Challenges to Sustainable Water

    E-print Network

    Cushing, Jim. M.

    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

  17. Water Wise: A Water Use Handbook.

    ERIC Educational Resources Information Center

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

    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…

  18. Cleaner, Safer Water through Water Safety Plans

    E-print Network

    and a local university, the WSP process resulted in improvements at the drinking water treatment plantCS232615A Cleaner, Safer Water through Water Safety Plans National Center for Environmental Health (NCEH) Global Water, Sanitation, and Hygiene Team's Water Safety Plan Assistance 1.5 million deaths

  19. Campus Water Uses and Potential Water Efficiencies

    Microsoft Academic Search

    Calvin Kuo; Melany Hunt; John Onderdonk; Matthew Berbee

    2008-01-01

    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

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

    E-print Network

    Waliser, Duane E.

    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

  1. Principles of Water Quality

    SciTech Connect

    Waite, T.D.

    1984-01-01

    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.

  2. Be Water Wise.

    ERIC Educational Resources Information Center

    Birch, Sandra K.; Pettus, Alvin M.

    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…

  3. 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.

  4. Water Resources of Wisconsin

    NSDL National Science Digital Library

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

  5. Water Science for Schools

    NSDL National Science Digital Library

    Howard Perlman

    This U.S. Geological Survey (USGS) water resources site provides comprehensive coverage of water related issues, and includes several interactive quizzes and activities for children. Here you will find information on many aspects of water, along with pictures, data, maps, and an interactive center. Topics include: Earth's water, Water basics, Water use, Water Questions and Answers, Activity center, Picture Gallery, Glossary, and Related Water Links. A special topics section tackles current problems in water science, including acid rain and water quality. The site also focuses on water use issues and attempts to raise student awareness of water conservation.

  6. Water resources data, Arizona, water year 2004

    USGS Publications Warehouse

    Fisk, G.G.; Duet, N.R.; McGuire, E.H.; Angeroth, C.E.; Castillo, N.K.; Smith, C.F.

    2005-01-01

    The USGS Arizona Water Science Center water data report includes records on both surface water and ground water in the State for water year 2004. Specifically, it contains: (1) Discharge records for 206 streamflow-gaging stations and 21 crest-stage, partial-record streamflow stations; (2) stage and (or) content records for 8 lakes and reservoirs; (3) water-quality records for 20 streamflow-gaging stations; (4) ground-water levels and compaction values for 14 stations; and (5) water levels for 18 wells.

  7. Water Wonders

    NSDL National Science Digital Library

    2012-08-03

    Students will be introduced to different species of macroinvertebrates. They will hypothesize why each insect looks the way it does. Then students will make observations of macroinvertebrates in an aquarium in their classroom. For an optional extension, teachers can take students to a local stream or pond to conduct field observations. Materials needed include sand, water, aquatics plants and insects; estimated materials cost does not include aquarium. This is the 3rd of 3 sets of learning activities that are companion activities to the Elementary GLOBE children's book, Discoveries at Willow Creek. Includes a teacher implementation guide.

  8. Water watch

    SciTech Connect

    Not Available

    1991-06-01

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

  9. Visible-light photocatalysis in Cu2Se nanowires with exposed {111} facets and charge separation between (111) and (1[combining macron]1[combining macron]1[combining macron]) polar surfaces.

    PubMed

    Liu, Bin; Ning, Lichao; Zhao, Hua; Zhang, Congjie; Yang, Heqing; Liu, Shengzhong Frank

    2015-05-13

    The search for active narrow band gap semiconductor photocatalysts that directly split water or degrade organic pollutants under solar irradiation remains an open issue. We synthesized Cu2Se nanowires with exposed {111} facets using ethanol and glycerol as morphology controlling agents. The {111} facets were found to be the active facets for decomposing organic contaminants in the entire solar spectrum. Based on the polar structure of the Cu2Se {111} facets, a charge separation model between polar (111) and (1[combining macron]1[combining macron]1[combining macron]) surfaces is proposed. The internal electric field between polar (111) and (1[combining macron]1[combining macron]1[combining macron]) surfaces created by spontaneous polarization drives charge separation. The reduction and oxidation reactions occur on the positive (111) and negative (1[combining macron]1[combining macron]1[combining macron]) polar surfaces, respectively. This suggests the surface-engineering of narrow band gap semiconductors as a strategy to fabricate photocatalysts with high reactivity in the entire solar spectrum. The charge separation model can deepen the understanding of charge transfer in other semiconductor nanocrystals with high photocatalytic activities and offer guidance to design more effective photocatalysts as well as new types of solar cells, photoelectrodes and photoelectric devices. PMID:25920433

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    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.

  11. Water resources data, Alaska, water year 2005

    USGS Publications Warehouse

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

    2006-01-01

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

  12. Water Safety Quiz

    MedlinePLUS

    ... Disaster or Emergency › Types of Emergency › Water Safety Water Safety Quiz Trivia quiz loading... Please enable javascript. Stay Safe around Water Download water safety tips in English or Spanish ...

  13. Learn about Water

    MedlinePLUS

    ... Facebook Twitter Google+ Pinterest Contact Us Learn about Water When the water in our rivers, lakes, and ... we swim and fish. See all water resources . Water Bodies Oceans, Coasts, Estuaries and Beaches Rivers and ...

  14. Water Science School

    MedlinePLUS

    The USGS Water Science School The USGS Water Science School Welcome to the U.S. Geological Survey's ( USGS ) Water Science School. We offer information on many aspects of water, along with pictures, ...

  15. Water: Consumer Information

    MedlinePLUS

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

  16. Private Ground Water Wells

    MedlinePLUS

    ... Water Healthy Water Home Share Compartir Private Ground Water Wells Many people in the United States receive ... answers to frequently asked questions about wells . Ground Water and Wells When rain falls, much of it ...

  17. Build a Kit: Water

    MedlinePLUS

    ... your family’s needs during an emergency. How Much Water Do I Need? You should store at least ... of water per person. How Should I Store Water? It is recommended you purchase commercially bottled water, ...

  18. Lead and tap water

    MedlinePLUS

    Water contaminated with lead ... The Environmental Protection Agency (EPA) monitors drinking water and requires water suppliers to produce annual water quality reports. These reports, which include information about lead amounts, are available to consumers. For ...

  19. Important Water Quality Factors

    NSDL National Science Digital Library

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

  20. Land and water snails

    NSDL National Science Digital Library

    Olivia Worland (Purdue University; Biological Sciences)

    2008-06-03

    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.

  1. Sodium in Drinking Water

    MedlinePLUS

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

  2. Autoionization of water

    NSDL National Science Digital Library

    Craig Merlic

    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.

  3. Drinking Water Standards 

    E-print Network

    Dozier, Monty; McFarland, Mark L.

    2006-04-26

    This publication explains the federal safety standards for drinking water provided by public water supply systems. It discusses the legal requirements for public water supplies, the maximum level allowed for contaminants in the water...

  4. Reduction of Water Consumption

    E-print Network

    Adler, J.

    REDUCTION OF WATER CONSUMPTION John Adler The Munters Corporation Ft. Myers, Florida 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...

  5. Everyone into the Water!

    ERIC Educational Resources Information Center

    Hennessey, Christina L.

    2007-01-01

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

  6. Testing the Waters.

    ERIC Educational Resources Information Center

    Finks, Mason

    1993-01-01

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

  7. Contested water rights

    Microsoft Academic Search

    Erik Ansink; Hans-Peter Weikard

    2009-01-01

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

  8. Waters of the Earth

    NSDL National Science Digital Library

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

  9. Water Pollution Control Legislation

    E-print Network

    Pasternack, Gregory B.

    ) administer many of the Clean Water Act's provisions. This law addresses water pollution and water quality, including pollution from irrigated agriculture. FEDERAL LAWS Clean Water Act -- 1972 and 1987 The Federal Water Pollution Control Act Amendments of 1972 and 1987, known as the Clean Water Act, are the principal

  10. Valuing Water Supply Reliability

    Microsoft Academic Search

    Ronald C. Griffin; James W. Mjelde

    2000-01-01

    Instead of creating water supply systems that fully insulate mankind from climate-imposed water deficiencies, it is possible that for municipal water systems a nonzero probability of water supply shortfall is efficient. Perfect water supply reliability, meaning no chance of future shortfall, is not optimal when water development costs are high. Designing an efficient strategy requires an assessment of consumer preferences

  11. Household Water Quality Home Water Quality Problems

    E-print Network

    Liskiewicz, Maciej

    , appearance or staining. Waterrelated problems will be found primarily in homes serviced by a private waterHousehold 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

  12. Water 3: Accounting For Our Water Needs

    NSDL National Science Digital Library

    2012-12-19

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

  13. WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE

    E-print Network

    Nebraska-Lincoln, University of

    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

  14. WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE

    E-print Network

    Nebraska-Lincoln, University of

    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

  15. WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE

    E-print Network

    Nebraska-Lincoln, University of

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

  16. WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE

    E-print Network

    Nebraska-Lincoln, University of

    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

  17. WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE

    E-print Network

    Nebraska-Lincoln, University of

    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

  18. WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE

    E-print Network

    Nebraska-Lincoln, University of

    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

  19. WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE

    E-print Network

    Nebraska-Lincoln, University of

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

  20. WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE

    E-print Network

    Nebraska-Lincoln, University of

    of water to all major social issues is finally driven home. The energy crisis is a case in point. Water and energy are inextricably bound. Energy is consumed and sometimes produced by every form of water resources for reductions in energy consumption through prudent water development and management. Technological, political

  1. Water Sensors

    NASA Technical Reports Server (NTRS)

    1992-01-01

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

  2. Water Resources Data, Arizona, Water Year 2003

    USGS Publications Warehouse

    Fisk, G.G.; Duet, N.R.; Evans, D.W.; Angeroth, C.E.; Castillo, N.K.; Longsworth, S.A.

    2004-01-01

    The Arizona District water data report includes records on both surface water and ground water in the State for water year 2003. Specifically, it contains: (1) discharge records for 203 streamflow-gaging stations, for 29 crest-stage, partial-record streamflow stations, and 50 miscellaneous sites; (2) stage and (or) content only records for 9 lakes and reservoirs; (3) water-quality records for 29 streamflow-gaging stations; (4) ground-water levels and compaction values for 14 stations; and (5) water levels for 19 wells.

  3. Water resources data, Indiana, water year 1992

    USGS Publications Warehouse

    Stewart, James A.; Keeton, Charles R.; Benedict, Brian L.; Hammil, Lowell E.

    1993-01-01

    Water resources data for the 1992 water year for Indiana consist of records of discharge, stage, and water quality of streams and wells; reservoir stage and contents; and water levels in lakes and wells. This report contains records of discharge for 175 stream-gaging stations, stage for 7 stream stations, 1 sediment station, stage and contents for 1 reservoir, water quality for 3 streams, and water levels for 80 lakes and 94 observation wells. These data represent that part of the National Water Data System operated by the U.S. Geological Survey in Indiana in cooperation with State and Federal agencies.

  4. Water resources data, Indiana, water year 1993

    USGS Publications Warehouse

    Stewart, James A.; Keeton, Charles R.; Benedict, Brian L.; Hammil, Lowell E.

    1994-01-01

    Water resources data for the 1993 water year for Indiana consist of records of discharge, stage, and water quality of streams and wells; reservoir stage and contents; and water levels in lakes and wells. This report contains records of discharge for 175 stream-gaging station, stage for 5 stream station, 1 sediment station, stage and contents for 1 reservoir, water quality for 3 streams, and water levels for 80 lakes and 94 observation wells. These data represent that part of the National Water Data System operated by the U.S. Geological Survey in Indiana in cooperation with State and Federal agencies.

  5. THE WATER CYCLE/ CLOUDS

    NSDL National Science Digital Library

    Ms.Brown

    2009-04-06

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

  6. 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.

  7. 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...

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

    ERIC Educational Resources Information Center

    Glasser, L.

    2004-01-01

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

  9. Cooling Water System Optimization

    E-print Network

    Aegerter, R.

    2005-01-01

    distribution header on the top deck. Water flows from the distribution header through distribution valves to splash boxes that distribute the water to their respective hot water basins. Water then flows through the distribution nozzles and strikes a... splash plate located below each distribution nozzle. The splash plates act like spray nozzles to break up the water into droplets and to evenly distribute the water across the fill. As water falls through the fill, it contacts the air that is being...

  10. Water Resources Data, Indiana, Water Year 2003

    USGS Publications Warehouse

    Morlock, Scott E.; Nguyen, Hieu T.; Majors, Deborah K.

    2004-01-01

    Water resources data for the 2003 water year for Indiana consists of records of discharge, stage, and water quality of streams and wells; reservoir stage and contents; and water levels in lakes and wells. This report contains records of discharge for 148 stream-gaging stations, stage for 16 stream stations, stage and contents for 1 reservoir, water quality for 5 streams, water temperature at 17 sites, sediment analysis for 2 streams, water levels for 8 lakes and 88 observation wells. Also included are records of miscellaneous discharge measurements, miscellaneous levels and miscellaneous water-quality, not part of the systematic data-collection program. Data contained in this report represent that part of the National Water Information System operated by the U.S. Geological Survey in Indiana in cooperation with State and Federal agencies.

  11. Water resources data, Indiana, water year 2001

    USGS Publications Warehouse

    Stewart, James A.; Keeton, Charles R.; Hammil, Lowell E.; Nguyen, Hieu T.; Majors, Deborah K.

    2002-01-01

    Water resources data for the 2001 water year for Indiana consists of records of discharge, stage, and water quality of streams and wells; reservoir stage and contents; and water levels in lakes and wells. This report contains records of discharge for 163 stream-gaging stations, stage for 8 stream stations, stage and contents for 1 reservoir, water quality for 1 stream, water temperature at 11 sites, sediment analysis for 1 stream, water levels for 78 lakes and 88 observation wells. Also included are records of miscellaneous discharge measurements, miscellaneous levels and miscellaneous water-quality, not part of the systematic data-collection program. Data contained in this report represent that part of the National Water Data System operated by the U.S. Geological Survey in Indiana in cooperation with State and Federal agencies.

  12. Mass Production and High Photocatalytic Activity of ZnS Nanoporous Nanoparticles

    Microsoft Academic Search

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

    2005-01-01

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

  13. Water flow controller device

    SciTech Connect

    Fender, W.

    1980-07-01

    A description is given of a water flow controller device of the type used for connecting a solar collecting device to conventional facility plumbing and a water reservoir, which comprises: (A) a cold water source connector; (B) a hot water feed connector; (C) a collector supply connector; (D) a collector return connector; (E) a cold water inlet connector; (F) a bifurcated hot water outlet connector having a collector return channel and a hot water feed channel; (G) cold water line means connecting said cold water source connector to said cold water inlet connector; (H) collector supply line means connecting said collector; supply connector to said cold water lines means; (I) hot water line means connecting said hot water feed channel of said bifurcated hot water outlet connector to said hot water feed connector; (J) collector line means connecting said collector return channel of said bifurcated hot water outlet connector to said collector return connector; (K) means for circulating water connected within said collector supply line means; (L) means for controlling said circulating means electrically connected to said circulating means; and (M) whereby said cold water source connector may be connected to a cold water source line of said facility plumbing; said hot water feed connector may be connected to a hot water feed line of said facility plumbing; said collector supply connector may be connected to a supply of said solar collecting devise; said collector return connector may be connected to a return line from said solar collecting device; said cold water inlet connector may be connected to a cold water inlet of said water reservior; and said bifurcated hot water connector may be connected to a hot water outlet of said water reservoir.

  14. Water Remediation Lab

    NSDL National Science Digital Library

    2014-09-18

    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.

  15. Water Basins Civil Engineering

    E-print Network

    Provancher, William

    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

  16. Primer on Water Quality

    MedlinePLUS

    ... fs-027-01.pdf--665KB A Primer on Water Quality What is in the water? Is it safe for drinking? Can fish and ... affect water quality. What do we mean by "water quality"? Water quality can be thought of as ...

  17. Water Governance and Legislation

    NSDL National Science Digital Library

    2003-07-31

    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.

  18. Grains, Water Introduction

    E-print Network

    Wirosoetisno, Djoko

    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

  19. Water Resources Milind Sohoni

    E-print Network

    Sohoni, Milind

    TD 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 kilos of sugar. Though the source of water in all the three cases is usually different. Agriculture

  20. Water Regulation I. Osmoregulation

    E-print Network

    Dever, Jennifer A.

    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

  1. Water Regulation I. Osmoregulation

    E-print Network

    Dever, Jennifer A.

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

  2. Water Regulation I. Osmoregulation

    E-print Network

    Dever, Jennifer A.

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

  3. Water Regulation I. Osmoregulation

    E-print Network

    Dever, Jennifer A.

    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

  4. Cloud Liquid Water Measurements

    E-print Network

    Delene, David J.

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

  5. Arkansas Water Resources Center

    E-print Network

    Soerens, Thomas

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

  6. Human Water Cycle

    NSDL National Science Digital Library

    2014-09-18

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

  7. Plant Water Relations

    NSDL National Science Digital Library

    Jim Bidlack

    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.

  8. Save Our Water Resources.

    ERIC Educational Resources Information Center

    Bromley, Albert W.

    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…

  9. Water Quality: An Introduction

    ERIC Educational Resources Information Center

    Merritt, LaVere B.

    1977-01-01

    An overview of the various aspects of water quality, including a rationale for multidisciplinary cooperation in water quality management, a list of beneficial water uses, a discussion of the major types of water pollutants, and an explanation of the use of aquatic biota in testing for water quality. (CS)

  10. Arkansas Water Resources Center

    E-print Network

    Soerens, Thomas

    water contaminants be- cause they can enter the ground water when the limestone is dissolved by carbonic at concentration levels which might lead to contamination of ground water to undesirably high levels. AnalysesArkansas Water Resources Center TRACE METAL AND MAJOR ELEMENTS IN WATER- SOLUBLE ROCKS OF NORTHWEST

  11. Arkansas Water Resources Center

    E-print Network

    Soerens, Thomas

    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

  12. Acid in water

    NSDL National Science Digital Library

    Laszlo Ilyes (None; )

    2007-05-16

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

  13. Water resources data, Indiana, water year 2000

    USGS Publications Warehouse

    Stewart, James A.; Keeton, Charles R.; Hammil, Lowell E.; Nguyen, Hieu T.; Majors, Deborah K.

    2001-01-01

    Water resource data for the 2000 water year for Indiana consists of records of discharge, stage, and water quality of streams and wells; reservoir stage and contents; and water levels in lakes and wells. This report contains records of discharge for 166 stream-gaging stations, stage for 7 stream stations, stage and contents for 1 reservoir, water quality for 2 streams, sediment analysis for 1 stream, water levels for 79 lakes and 89 observation wells. Also included are records of miscellaneous discharge measurements, miscellaneous levels and miscellaneous water-quality, not part of the systematic data-collection program. Data contained in this report represent that part of the the National Water Data System operated by the U.S. Geological Survey in Indiana in cooperation with State and Federal agencies.

  14. Global monthly water stress: 1. Water balance and water availability

    NASA Astrophysics Data System (ADS)

    van Beek, L. P. H.; Wada, Yoshihide; Bierkens, Marc F. P.

    2011-07-01

    Surface fresh water (i.e., blue water) is a vital and indispensable resource for human water use in the agricultural, industrial, and domestic sectors. In this paper, global water availability is calculated by forcing the global hydrological model PCR-GLOBWB with daily global meteorological fields for the period 1958-2001. To represent blue water availability, a prognostic reservoir operation scheme was included in order to produce monthly time series of global river discharge modulated by reservoir operations. To specify green water availability for irrigated areas, actual transpiration from the model was used. Thus, the computed water availability reflects the climatic variability over 1958-2001 and is contrasted against the monthly water demand using the year 2000 as a benchmark in the companion paper. As the water that is withdrawn to meet demand directly interferes with blue water availability along the drainage network, this paper evaluates model performance for three regimes reflecting different degrees of human interference: natural discharge, discharge regulated by reservoirs, and modified discharge. In the case of modified discharge, the net blue water demand for the year 2000 is subtracted directly from the regulated discharge, taking water demand equal to consumptive water use. Results show that model simulations of monthly river discharge compare well with observations from most of the large rivers. Exceptions are basins subject to large extractions for irrigation purposes, where simulated discharge exceeds the observations even when water demand is taken into account. Including the prognostic reservoir operation scheme results in mixed performance, with a poorer approximation of peak flows but with a marginally better simulation of low flows and persistence. A comparison of simulated actual evapotranspiration with that from the ERA-40 reanalysis as a proxy for observed rates shows similar patterns over nonirrigated areas but substantial deviations over major irrigated areas. As expected, assimilated actual evapotranspiration over these areas includes water from alternative sources, whereas the simulations with PCR-GLOBWB are limited by soil moisture, i.e., green water availability. On the basis of this evidence we conclude that the simulation provides adequate fields of water availability to assess water stress at the monthly scale, for which a separate validation is provided in the companion paper.

  15. 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...

  16. WATER RESOURCES NEBRASKA WATER RESOURCES RESEARCH INSTITUTE

    E-print Network

    Nebraska-Lincoln, University of

    ~ 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-economic impacts of energy use reductions? (9) How can the environmental impact of water-power develop- ment

  17. WATER RESOURCES ,'JEBRASKA WATER RESOURCES RESEARCH INSTITUTE

    E-print Network

    Nebraska-Lincoln, University of

    The Nebraska Institute is sponsoring a conference entitled liThe Role of Water in the Energy Crisis. 1I in which the water re- sources community can help solve or alleviate national and regional energy problems. Topics to be discussed will include various aspects of energy-water relationships (economic

  18. Water quality models for waste water management

    Microsoft Academic Search

    Paul G. Whitehead

    A methodology is proposed for evaluating the impact of effluent on the aquatic environment and for the development of management strategies for the planning and control of waste water systems. The particular approach considers the dynamic behaviour of the river system and relates time varying upstream influents to downstream water quality using simple, low order but robust models of water

  19. 1999 WATER RESOURCES SEMINARS "Spotlighting Water Research"

    E-print Network

    Nebraska-Lincoln, University of

    , Associate Professor/Research Hydrogeologist April 21: "Water Quality at Confined Animal Waste Lagoons1999 WATER RESOURCES SEMINARS "Spotlighting Water Research" Wednesdays/3:00 to 3:50 p.m./116 L. W. Chase Hall/UNL East Campus January 13: KREMER LECTURE: "Locally Directed Resources Management Needs

  20. National Drinking Water Clearinghouse

    MedlinePLUS

    Drinking Water Read On Tap Latest Issue The National Drinking Water Clearinghouse (NDWC) is a public service organization dedicated ... developing, and providing timely information relevant to drinking water issues. We provide free and low-cost publications, ...

  1. Tsunamis: Water Quality

    MedlinePLUS

    ... Landslides Tornadoes Tsunamis Volcanoes Wildfires Winter Weather Tsunamis: Water Quality Language: English Español (Spanish) Recommend on Facebook ... about testing should be directed to local authorities. Water for Drinking, Cooking, and Personal Hygiene Safe water ...

  2. Water safety and drowning

    MedlinePLUS

    ... among people of all ages. Learning and practicing water safety is important to prevent drowning accidents. ... Water safety tips for all ages include: Learn CPR. Never swim alone. Never dive into water unless ...

  3. Lawn Water Management

    E-print Network

    McAfee, James

    2006-06-26

    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...

  4. water transport land runoff

    E-print Network

    Torgersen, Christian

    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

  5. 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,...

  6. Sinking and Floating Water

    NSDL National Science Digital Library

    nancy thill

    This activity is a classroom lab where students learn that cold water is denser and hot water is less dense than room temperature water. Students perform an experiment and relate to their background knowledge to make conjectures.

  7. Lawn Water Management 

    E-print Network

    McAfee, James

    2006-06-26

    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...

  8. 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...

  9. Ground Water Remediation Technologies

    EPA Science Inventory

    The USEPA's Ground Water and Ecosystems Restoration Division (GWERD) conducts research and provides technical assistance to support the development of strategies and technologies to protect and restore ground water, surface water, and ecosystems impacted by man-made and natural...

  10. Local Drinking Water Information

    MedlinePLUS

    ... a short report (consumer confidence report, or drinking water quality report) from your water supplier that tells where ... what's in it: see if your annual drinking water quality report is posted on-line , read some frequent ...

  11. The Science of Water

    NSDL National Science Digital Library

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

    2010-01-01

    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.

  12. Treatment of Well Water

    MedlinePLUS

    ... water softener is a device that reduces the hardness of the water. A water softener typically uses sodium or potassium ions to replace calcium and magnesium ions, the ions that create "hardness." Distillation Systems Distillation is a process in which ...

  13. Industrial Water Use

    NSDL National Science Digital Library

    2002-10-10

    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.

  14. Technology in water conservation

    E-print Network

    Finch, Dr. Calvin

    2013-01-01

    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...

  15. 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.

  16. Walk On Water Bugs

    NSDL National Science Digital Library

    2014-01-28

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

  17. 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.

  18. Water-heating dehumidifier

    DOEpatents

    Tomlinson, John J. (Knoxville, TN)

    2006-04-18

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

  19. Ferroelectric mobile water.

    PubMed

    Nakamura, Yoshimichi; Ohno, Takahisa

    2011-01-21

    In molecular dynamics simulations single-domain ferroelectric water is produced under ordinary ambient conditions utilizing carbon nanotubes open to a water reservoir. This ferroelectric water diffuses while keeping its proton-ordered network intact. The mobile/immobile water transitions and the step-wise changes in net polarization of water are observed to occur spontaneously. The immobile water becomes mobile by transforming into the single-domain ferroelectric water. Our general notion of relating a more highly ordered structure with a lower temperature has so far restricted researchers' attention to very low temperatures when experimenting on proton-ordered phases of water. The present study improves our general understanding of water, considering that the term 'ferroelectric water' has so far practically stood for 'ferroelectric ice,' and that single-domain ferroelectric water has not been reported even for the ice nanotubes. PMID:21072393

  20. Sustainability and Water

    NASA Astrophysics Data System (ADS)

    Sharma, Virender A.

    2009-07-01

    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.

  1. Photobiocatalysis: The Power of Combining Photocatalysis and Enzymes.

    PubMed

    Maciá-Agulló, Juan Antonio; Corma, Avelino; Garcia, Hermenegildo

    2015-07-27

    Photobiocatalysts are constituted by a semiconductor with or without a light harvester that activates an enzyme. A logical source of inspiration for the development of photobiocatalysts has been natural photosynthetic centers. In photobiocatalysis, the coupling of the semiconductor and the enzyme frequently requires a natural cofactor and a relay transferring charge carriers from the semiconductor. The most widely studied photobiocatalysts so far make use of conduction band electrons of excited semiconductors to promote enzymatic reductions mediated by NAD(+) /NADH and an electron relay. The present review presents the state of the art in the field and has been organized based on the semiconductor and the reaction type including oxidations, hydrogen generation, and CO2 reduction. The possibility of direct enzyme activation by the semiconductor and the influence of the nature of mediator are also discussed as well as the use of mimics of the enzyme active center in combination with the semiconductor. The final section summarizes the state of the art of photobiocatalysis and comments on our view on future developments of the field. PMID:26014675

  2. Photocatalysis for renewable energy production using PhotoFuelCells.

    PubMed

    Michal, Robert; Sfaelou, Stavroula; Lianos, Panagiotis

    2014-01-01

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

  3. Electronic Supplementary Information (26 Pages) Supramolecular Photocatalysis by Confinement

    E-print Network

    Jayaraman, Sivaguru

    . Comparison of photoproduct selectivity upon photoirradiation with sunlight and with medium pressure mercury lamp. 13. Optimized structure and volume of photodimers 2-5 14. Geometric parameters for photodimers 2

  4. Photocatalysis and Photoelectrochemical Properties of Tungsten Trioxide Nanostructured Films

    PubMed Central

    Lai, Chin Wei

    2014-01-01

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

  5. Removal of emergent contaminants: integration of ozone and photocatalysis.

    PubMed

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

    2012-06-15

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

  6. Applications of TiO 2 Photocatalysis for Air Purification

    Microsoft Academic Search

    Anne Beeldens; Luigi Cassar; Yoshihiko Murata

    \\u000a A system consisting of TiO2 and cement has recently been studied within the framework of a strategy for alleviating environmental pollution through the\\u000a use of construction materials containing photocatalysts. This technology for the photocatalytic degradation of organic pollutants\\u000a is aimed at maintaining the aesthetic characteristics of concrete structures, particularly those based on white cement. The\\u000a main reason for the discoloration

  7. Integration of Solar Photocatalysis and Membrane Bioreactor for Pesticides Degradation

    Microsoft Academic Search

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

    2010-01-01

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

  8. Recovery of silver metal from low concentrated wastewater by photocatalysis

    NASA Astrophysics Data System (ADS)

    Ding, Mali; Han, Jie; Qiu, Wei; Zhang, Weijun; Gao, Wei

    2015-03-01

    This work studies the photocatalytic activity of zinc oxide (ZnO) nanopowder to recover silver (Ag) metal from low Ag+ concentrated solution under artificial ultraviolet (UV) light. Benchmark titanium dioxide (P25 TiO2) was used for comparison purpose. Experimental results indicated that ZnO exhibited superior performance for Ag recovery compared to TiO2. Under optimal catalyst loading, the achieved Ag removal efficiencies were 100% and 99.94% at 0.2 g/L ZnO (1 h) and 2 g/L TiO2 (2 h), respectively. An induction period at low concentration of TiO2 (0.1 g/L) was observed and a mechanism was proposed. The photodissolution of ZnO was assessed and proved to be negligible. Recovered pure Ag metal was characterized by X-ray diffractometry (XRD) and scanning electron microscopy (SEM), showing a promising effective Ag recovery technology using ZnO photocatalyst.

  9. Cerium doped nanotitania—extended spectral response for enhanced photocatalysis

    NASA Astrophysics Data System (ADS)

    Priyanka, K. P.; Anu Tresa, S.; Jaseentha, O. P.; Varghese, Thomas

    2014-03-01

    Titania nanoparticles were synthesized using the sol-gel method. Nano-sized Ce particles were doped into nanotitania using the metal sol method. As-synthesized TiO2 and Ce doped TiO2 nanoparticles were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible spectroscopy and photoluminescence (PL) spectroscopy. Photocatalytic degradation of methylene blue by undoped and ceria-doped titania was investigated under visible light. The dye degradation capabilities of nano-sized Ce-TiO2 catalysts were found to be superior to undoped TiO2 nanoparticles. The higher photoactivity of TiO2 can be ascribed to the effect of Ce dopants on band gap narrowing, and acting as electron traps on the Ce-TiO2 surface. Dye degradation studies show that nanotitania doped with Ce is suitable for higher photocatalytic activity under visible light.

  10. Semiconductor nanowire array: potential substrates for photocatalysis and photovoltaics

    E-print Network

    Yang, Peidong

    cluster as solvent at high temperature. Based on Si­Au binary phase diagram, Si (from the decomposition. A well-accepted mechanism of nanowire growth via gas phase reaction is the so-called Vapor­ Liquid alloy­solid interface. This process is illustrated in figure 1 for the growth of Si nanowire with Au

  11. Photocatalysis of fenoxycarb over silver-modified zeolites.

    PubMed

    Ahern, John; Kanan, Sofian; Sara, Ziad; Job, Thomas; Alnaizy, Raafat; Abu Farha, Nedal; Patterson, Howard

    2015-03-01

    Two samples of silver doped into zeolite Y were prepared and characterized. ICP and SEM-EDS analysis indicate that the AgY1 sample contains twice the amount of silver compared to the AgY2 sample. Solid state luminescence spectroscopy shows variations in the emission modes of the site-selective luminescence where various luminophores might be excited upon selecting the proper excitation energy. The selected material effectively decomposed the pesticide fenoxycarb in aqueous solution. The photodecomposition of fenoxycarb reached 80 % upon irradiation for 60 min in the presence of the AgY1 catalyst. 2-(4-Phenoxy-phenoxy)ethyl] carbamic acid (1) and 1-amine-2-(phenoxy-4-ol) ethane (2) were identified as products for both uncatalyzed solution and the catalyzed fenoxycarb with AgY2 catalyst. Whereas, compound (2) was the only product identified in the catalyzed reaction with AgY1. PMID:24562452

  12. Kinetic study of acetaminophen degradation by visible light photocatalysis.

    PubMed

    Gotostos, Mary Jane N; Su, Chia-Chi; De Luna, Mark Daniel G; Lu, Ming-Chun

    2014-01-01

    In this work, a novel photocatalyst K3[Fe(CN)6]/TiO2 synthesized via a simple sol-gel method was utilized to degrade acetaminophen (ACT) under visible light with the use of blue and green LED lights. Parameters (medium pH, initial concentration of reactant, catalyst concentration, temperature, and number of blue LED lights) affecting photocatalytic degradation of ACT were also investigated. The experimental result showed that compared to commercially available Degussa P-25 (DP-25) photocatalyst, K3[Fe(CN)6]/TiO2 gave higher degradation efficiency and rate constant (kapp) of ACT. The degradation efficiency or kapp decreased with increasing initial ACT concentration and temperature, but increased with increased number of blue LED lamps. Additionally, kapp increased as initial pH was increased from 5.6 to 6.9, but decreased at a high alkaline condition (pH 8.3). Furthermore, the degradation efficiency and kapp of ACT increased as K3[Fe(CN)6]/TiO2 loading was increased to 1 g L(-1) but decreased and eventually leveled off at photocatalyst loading above this value. Photocatalytic degradation of ACT in K3[Fe(CN)6]/TiO2 catalyst system follows a pseudo-first-order kinetics. The Langmuir-Hinshelwood equation was also satisfactorily used to model the degradation of ACT in K3[Fe(CN)6]/TiO2 catalyst system indicated by a satisfactory linear correlation between 1/kapp and Co, with kini = 6.54 × 10(-4) mM/min and KACT = 17.27 mM(-1). PMID:24766590

  13. Solar light induced degradation of reactive dye using photocatalysis.

    PubMed

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

    2004-01-01

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

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

    PubMed

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

    2013-01-01

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

  15. Green Photocatalysis for Degradation of Organic Contaminants: A Review

    EPA Science Inventory

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

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

    Microsoft Academic Search

    L. Glasser

    2004-01-01

    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.

  17. Muddy Waters . . . page 4

    E-print Network

    Pringle, James "Jamie"

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

  18. Water Resources Milind Sohoni

    E-print Network

    Sohoni, Milind

    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

  19. Water Resources Milind Sohoni

    E-print Network

    Sohoni, Milind

    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

  20. Water Resources Milind Sohoni

    E-print Network

    Sohoni, Milind

    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

  1. Water Resources Milind Sohoni

    E-print Network

    Sohoni, Milind

    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

  2. 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

  3. The Amazing Water Trick

    NSDL National Science Digital Library

    2012-06-26

    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.

  4. Old Water Pump

    USGS Multimedia Gallery

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

  5. Irrigation Water Quality 

    E-print Network

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

    2002-04-11

    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...

  6. Lifting China's water spell.

    PubMed

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

    2014-10-01

    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 tones 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

  7. Improve plant water quality

    Microsoft Academic Search

    1983-01-01

    Producing high quality water for various inplant usages reliably and cost efficiently is of prime concern. DuPont's Beaumont Works is no exception. The production of ammonia, aniline, acrylonitrile, methanol, tetraethyl lead, and various proprietary products requires high quality water for boiler water makeup, cooling tower makeup, and various process systems. In addition, potable water is produced. For the past nine

  8. Arkansas Water Resources Center

    E-print Network

    Soerens, Thomas

    evolution of arsenic in ground water: tracking sources and sinks in the alluvial aquifer of southeastern Arkansas, USA Basic Information Title: Flow and hydrochemical evolution of arsenic in ground water: ground water, geochemical evolution, arsenic, sediment/water interaction, alluvial aquifer, geochemical

  9. Global Water Distribution

    NSDL National Science Digital Library

    2005-12-17

    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.

  10. Cooling water system design

    Microsoft Academic Search

    Jin-Kuk Kim; Robin Smith

    2001-01-01

    Research on cooling systems to date has focussed on the individual components of cooling systems, not the system as a whole. Cooling water systems should be designed and operated with consideration of all the cooling system components because of the interactions between cooling water networks and the cooling tower performance. In re-circulating cooling water systems, cooling water from the cooling

  11. Arkansas Water Resources Center

    E-print Network

    Soerens, Thomas

    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

  12. Arkansas Water Resources Center

    E-print Network

    Soerens, Thomas

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

  13. Can Water Mean Health?

    ERIC Educational Resources Information Center

    Black, Maggie, Ed.

    1983-01-01

    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…

  14. Ultraviolet water purifier

    Microsoft Academic Search

    D. N. Lambert; R. H. Bennett

    2009-01-01

    An ultraviolet water purifier has a number of ultraviolet lamps mounted in a cover which extends over the purifier and above the water. A parabolic reflector directs the rays of the lamps toward the body of water. The purifier is provided with a water inlet and a baffle adjacent to it having an opening at its base to compel the

  15. Reflections on Water (and \\

    Microsoft Academic Search

    Barbara C. Malt

    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

  16. Potable water supply

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

    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.

  17. Domestic wash water reclamation

    NASA Technical Reports Server (NTRS)

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

    1974-01-01

    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.

  18. Energy---Water Interdependence

    Microsoft Academic Search

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

    2010-01-01

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

  19. Arkansas Water Resources Center

    E-print Network

    Soerens, Thomas

    that ground water contamination by pesticides is a widespread problem in the U. S. In response the EPAArkansas Water Resources Center Publication No. MSC-224 PESTICIDE GROUND WATER MONITORING PROJECT~~PLETION REPORT ARKANSAS STATE PLANT BOARD PESTICIDE GROUND WATER MONITORING PROJECT FOR MOST VULNERABLE AREAS

  20. Arkansas Water Resources Center

    E-print Network

    Soerens, Thomas

    with Modified DRASTIC Parameters to Predict Ground Water Contamination Introduction 16 Objectives 17 MethodologyArkansas Water Resources Center VULNERABILITY AND USE OF GROUND AND SURFACE WATERS IN THE SOUTHERN displacementexperimentalcondition ,.. 10 Project A2: Use of Fuzzy Logic with Modified DRASTIC Parameters to Predict Ground Water

  1. Arkansas Water Resources Center

    E-print Network

    Soerens, Thomas

    potential sources of contaminants, especially nitrate. A suJrvey of ground water nitrate conc4entrationsArkansas Water Resources Center NITRATE CONCENTRATIONS OF GROUND WATER BENTON COUNTY, ARKANSAS, Arkansas 72701 #12;ABSTRACT Because 'ground water in fractured c;3.rbonate aquifers is particularly

  2. Arkansas Water Resources Center

    E-print Network

    Soerens, Thomas

    ground water contamination, 3) use of vegetative filter strips of varying widths to reduce herbicides loads (TMDLs) 3. declining ground water levels, especially in eastern Arkansas and associated salt waterArkansas Water Resources Center Publication No. MSC-102.1998 ANNUAL PROGRAM REPORT for the Period

  3. Arkansas Water Resources Center

    E-print Network

    Soerens, Thomas

    caused concern regarding nitrate contamination of the ground water. In the study area of Pike and Howard application. If the lagoons are improperly constructed and leak, they can contaminate ground waterArkansas Water Resources Center RECONNAISSANCE SURVEY OF NITRATE CONCENTRATIONS IN GROUND WATER

  4. Waves and Water Beetles

    ERIC Educational Resources Information Center

    Tucker, Vance A.

    1971-01-01

    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)

  5. Purge water management system

    Microsoft Academic Search

    J. E. Cardoso-Neto; D. W. Williams

    1995-01-01

    A purge water management system is described for effectively eliminating the production of purge water when obtaining a groundwater sample from a monitoring well. In its preferred embodiment, the purge water management system comprises an expandable container, a transportation system, and a return system. The purge water management system is connected to a wellhead sampling configuration, typically permanently installed at

  6. Purge water management system

    Microsoft Academic Search

    J. E. Cardoso-Neto; D. W. Williams

    1996-01-01

    A purge water management system is described for effectively eliminating the production of purge water when obtaining a groundwater sample from a monitoring well. In its preferred embodiment, the purge water management system comprises an expandable container, a transportation system, and a return system. The purge water management system is connected to a wellhead sampling configuration, typically permanently installed at

  7. Purge water management system

    Microsoft Academic Search

    Joao E. Cardoso-Neto; Daniel W. Williams

    1996-01-01

    A purge water management system for effectively eliminating the production of purge water when obtaining a groundwater sample from a monitoring well. In its preferred embodiment, the purge water management system comprises an expandable container, a transportation system, and a return system. The purge water management system is connected to a wellhead sampling configuration, typically permanently installed at the well

  8. Pricing China's irrigation water

    Microsoft Academic Search

    Michael Webber; Jon Barnett; Brian Finlayson; Mark Wang

    2008-01-01

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

  9. Potable water taste enhancement

    NASA Technical Reports Server (NTRS)

    1974-01-01

    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.

  10. 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.

  11. Water Cycle Animation

    NSDL National Science Digital Library

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

  12. Water Scarcity and Energy: Water and Power Efficiency of

    E-print Network

    Scott, Christopher

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

  13. The African Water Page

    NSDL National Science Digital Library

    Abrams, Leonard John.

    1995-01-01

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

  14. Irrigation Water Use

    NSDL National Science Digital Library

    2003-05-28

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

  15. The Water Filtration Process

    NSDL National Science Digital Library

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

  16. Water Resources of Utah

    NSDL National Science Digital Library

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

  17. The Water Sourcebooks

    NSDL National Science Digital Library

    2007-12-12

    The Water Sourcebooks contain 324 activities for grades K-12 divided into four sections: K-2, 3-5, 5-8, and 9-12. Each section is divided into five chapters: Introduction to Water, Drinking Water and Wastewater Treatment, Surface Water Resources, Ground Water Resources, and Wetlands and Coastal Waters. This environmental education program explains the water management cycle using a balanced approach, showing how it affects all aspects of the environment. All activities contain hands-on investigations, fact sheets, reference materials, and a glossary of terms. Activities are organized by objectives, materials needed, background information, advance preparation, procedures, and resources.

  18. Water Info For Kids

    NSDL National Science Digital Library

    The City of Phoenix Web offers the Water Info For Kids page as part of its larger governmental Web site. Six topics are covered including What is water?, What is the Hydrologic (Water) Cycle?, Where does our water come from?, Who uses water?, How can we take care of water?, and Phoenix water and wastewater facts. Each page contains non-technical text and colorful graphics making it especially good for younger students. And, although a "next" link would make the pages flow better from one to the next, the site does a good job of presenting the material in a fun and challenging way.

  19. Colorado Water Knowledge

    NSDL National Science Digital Library

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

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

    PubMed

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

    2012-04-15

    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