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Sample records for grade phosphoric acid

  1. Preparation of high purification and food grade phosphoric acid from technical grade phosphoric acid by liquid-liquid detraction method

    International Nuclear Information System (INIS)

    Alimoradi, M.; Borji, F.; Kishani, A.

    2002-01-01

    Pay attention to increasing consumption of high purification and food grade phosphoric acid in various industries and food industries and on in on hand and lack of preparation between production and distribution of this products its purification is so vital. In this article of liquid-liquid extraction method with normal hexane-mixture of ammonia and acetone-diisopropyl alcohol and normal butanol solvents and these determination of distribution coefficient each one with ph-me try titration we can evaluate effectiveness and sufficiency each one. Because of proper coefficient distribution and its local production of normal butanol solvent and low price is the best solvent. To phosphoric acid modifying coefficient distribution for extraction of phosphoric acid we can add a little value sulfuric acid to the mixture and to remove flouride impurity we add a little Na 2 O. After extraction stage extracted phosphoric acid in the normal strips by evaluating with distilled water and then by passing the carbon active bed and following passes of cationic resine column and concentrated with vacuum distillation. Conclusion of this article is produce of phosphoric acid 85% w/w and food grade from impure phosphoric acid 52% w/w with technical grade

  2. Counter current extraction of phosphoric acid: Food grade acid production

    International Nuclear Information System (INIS)

    Shlewit, H.; AlIbrahim, M.

    2009-01-01

    Extraction, scrubbing and stripping of phosphoric acid from the Syrian wet-phosphoric acid was carried out using Micro-pilot plant of mixer settler type of 8 l/h capacity. Tributyl phosphate (TBP)/di-isopropyl ether (DIPE) in kerosene was used as extractant. Extraction and stripping equilibrium curves were evaluated. The number of extraction and stripping stages to achieve the convenient and feasible yield was determined. Detailed flow sheet was suggested for the proposed continuous process. Data obtained include useful information for the design of phosphoric acid extraction plant. The produced phosphoric acid was characterized using different analytical techniques. (author)

  3. Electrodialysis of Phosphates in Industrial-Grade Phosphoric Acid

    OpenAIRE

    Machorro, J. J.; Olvera, J. C.; Larios, A.; Hernández-Hernández, H. M.; Alcantara-Garduño, M. E.; Orozco, G.

    2013-01-01

    The objective of this research was to study the purification of industrial-grade phosphoric acid (P2O5) by conventional electrodialysis. The experiments were conducted using a three-compartment cell with anion and cation membranes, and industrial acid solution was introduced into the central compartment. The elemental analysis of the diluted solution indicated that the composition of magnesium, phosphates, and sodium was reduced in the central compartment. The ratios of the concentration of t...

  4. Titrimetric determination of uranium in low-grade ores by the ferrous ion-phosphoric acid reduction method

    International Nuclear Information System (INIS)

    Hitchen, A.; Zechanowitsch, G.

    1980-01-01

    The modification and extension of the U.S.A.E.C. ferrous ion-phosphoric acid reduction method for the determination of uranium in high-grade or relatively pure material to a method for the determination of uranium with a high accuracy and precision, in ores containing 0.004 to 7% U is described. It is simple, rapid and requires no prior separations from elements that, in other methods, frequently interfere. For sample materials having very high concentrations of interfering elements, a prior concentration step using extraction with tri-n-octylphosphine oxide is described, but it is shown that, for most low-grade ores, this step is unnecessary. (author)

  5. Uranium extraction from phosphoric acid

    International Nuclear Information System (INIS)

    Araujo Figueiredo, C. de

    1984-01-01

    The recovery of uranium from phosphoric liquor by two extraction process is studied. First, uranium is reduced to tetravalent condition and is extracted by dioctypyrophosphoric acid. The re-extraction is made by concentrated phosphoric acid with an oxidizing agent. The re-extract is submitted to the second process and uranium is extracted by di-ethylhexilphosphoric acid and trioctylphosphine oxide. (M.A.C.) [pt

  6. Uranium extraction from phosphoric acid

    International Nuclear Information System (INIS)

    Lounis, A.

    1983-05-01

    A study has been carried out for the extraction of uranium from phosphoric acid produced in Algeria. First of all, the Algerian phosphoric acid produced in Algeria by SONATRACH has been characterised. This study helped us to synthesize a phosphoric acid that enabled us to pass from laboratory tests to pilot scale tests. We have then examined extraction and stripping parameters: diluent, DZEPHA/TOPO ratio and oxidising agent. The laboratory experiments enabled us to set the optimum condition for the choice of diluent, extractant concentration, ratio of the synergic mixture, oxidant concentration, redox potential. The equilibrium isotherms lead to the determination of the number of theoretical stages for the uranium extraction and stripping of uranium, then the extraction from phosphoric acid has been verified on a pilot scale (using a mixer-settler)

  7. Recovering uranium from phosphoric acid

    International Nuclear Information System (INIS)

    Abodishish, H.A.; Ritchey, R.W.

    1982-01-01

    Precipitation of Fe 3 HN 4 H 8 (PO 4 ) 6 is prevented in the second cycle extractor, in a two cycle uranium recovery process, by washing ammonia laden organic solvent stream, from the second cycle stripper, with first cycle raffinate iron stream containing phosphoric acid, prior to passing the solvent stream into the second cycle extractor. (author)

  8. 21 CFR 182.1073 - Phosphoric acid.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Phosphoric acid. 182.1073 Section 182.1073 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN....1073 Phosphoric acid. (a) Product. Phosphoric acid. (b) Conditions of use. This substance is generally...

  9. 21 CFR 582.1073 - Phosphoric acid.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Phosphoric acid. 582.1073 Section 582.1073 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1073 Phosphoric acid. (a) Product. Phosphoric acid. (b) Conditions of use. This substance is...

  10. Uranium extraction in phosphoric acid

    International Nuclear Information System (INIS)

    Araujo Figueiredo, C. de

    1984-01-01

    Uranium is recovered from the phosphoric liquor produced from the concentrate obtained from phosphorus-uraniferous mineral from Itataia mines (CE, Brazil). The proposed process consists of two extraction cycles. In the first one, uranium is reduced to its tetravalent state and then extracted by dioctylpyrophosphoric acid, diluted in Kerosene. Re-extraction is carried out with concentrated phosphoric acid containing an oxidising agent to convert uranium to its hexavalent state. This extract (from the first cycle) is submitted to the second cycle where uranium is extracted with DEPA-TOPO (di-2-hexylphosphoric acid/tri-n-octyl phosphine oxide) in Kerosene. The extract is then washed and uranium is backextracted and precipitated as commercial concentrate. The organic phase is recovered. Results from discontinuous tests were satisfactory, enabling to establish operational conditions for the performance of a continuous test in a micro-pilot plant. (Author) [pt

  11. Application of strong phosphoric acid to radiochemistry

    International Nuclear Information System (INIS)

    Terada, Kikuo

    1977-01-01

    Not only inorganic and organic compounds but also natural substrances, such as accumulations in soil, are completely decomposed and distilled by heating with strong phosphoric acid for 30 to 50 minutes. As applications of strong phosphoric acid to radiochemistry, determination of uranium and boron by use of solubilization effect of this substance, titration of uranyl ion by use of sulfuric iron (II) contained in this substance, application to tracer experiment, and determination of radioactive ruthenium in environmental samples are reviewed. Strong phosphoric acid is also applied to activation analysis, for example, determination of N in pyrographite with iodate potassium-strong phosphoric acid method, separation of Os and Ru with sulfuric cerium (IV) - strong phosphoric acid method or potassium dechromate-strong phosphoric acid method, analysis of Se, As and Sb rocks and accumulations with ammonium bromide, sodium chloride and sodium bromide-strong phosphoric acid method. (Kanao, N.)

  12. Uranium extraction from phosphoric acid

    International Nuclear Information System (INIS)

    Ginisty, C.; Bathellier, A.

    1983-11-01

    The process developed is an improvement of the process using the synergetic mixture HD2 EHP/TOPO for uranium VI extraction. Better performances are obtained by introduction of oxygen in alkyl radicals of organophosphorus extractants by etheroxide functions. For industrial use the synergetic mixture di-n-hexyl octoxy methyl phosphine/hydrogeno-bis-di-1,3 butoxy-2-propyl phosphate is selected. Extraction coefficient is 3 times better than with the HD2 EHP/TOPO system. The complete process in one cycle was tested in a pilot plant with a flow rate of 60 l/h in phosphoric acid [fr

  13. Pretreatment of industrial phosphoric acid by Algerian filter-aids

    International Nuclear Information System (INIS)

    Mellah, A.; Setti, Louisa; Chegrouche, Salah

    1993-01-01

    The present work involves the filtration of industrial phosphoric acid by different filter-aids such as kieselguhr, celite and bleaching clay. The retention of substances contained in wet phosphoric acid was determined using the three filter-aids. Thus, the phosphoric acid, obtained by filtration on kieselguhr has the same specifications as technical phosphoric acid produced by Rhone-Poulenc (France) as standard

  14. Method of purifying phosphoric acid after solvent extraction

    International Nuclear Information System (INIS)

    Kouloheris, A.P.; Lefever, J.A.

    1979-01-01

    A method of purifying phosphoric acid after solvent extraction is described. The phosphoric acid is contacted with a sorbent which sorbs or takes up the residual amount of organic carrier and the phosphoric acid separated from the organic carrier-laden sorbent. The method is especially suitable for removing residual organic carrier from phosphoric acid after solvent extraction uranium recovery. (author)

  15. 46 CFR 151.50-23 - Phosphoric acid.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Phosphoric acid. 151.50-23 Section 151.50-23 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-23 Phosphoric acid. (a) The term phosphoric acid as used in this subpart shall include, in addition to phosphoric acid, aqueous solutions of...

  16. Radionuclide concentrations in raw and purified phosphoric acids from Brazil and their processing wastes: implications for radiation exposures.

    Science.gov (United States)

    da Conceição, Fabiano Tomazini; Antunes, Maria Lúcia Pereira; Durrant, Steven F

    2012-02-01

    Radionuclides from the U and Th natural series are present in alkaline rocks, which are used as feedstock in Brazil for the production of raw phosphoric acid, which can be considered as a NORM (naturally occurring radioactive material). As a result of the purification of raw phosphoric acid to food-grade phosphoric acid, two by-products are generated, i.e., solid and liquid wastes. Taking this into account, the main aim of this study was to evaluate the fluxes of natural radionuclide in the production of food-grade phosphoric acids in Brazil, to determine the radiological impact caused by ingestion of food-grade phosphoric acid, and to evaluate the solid waste environmental hazards caused by its application in crop soils. Radiological characterization of raw phosphoric acid, food-grade phosphoric acid, solid waste, and liquid waste was performed by alpha and gamma spectrometry. The (238)U, (234)U, (226)Ra, and (232)Th activity concentrations varied depending on the source of raw phosphoric acid. Decreasing radionuclides activity concentrations in raw phosphoric acids used by the producer of the purified phosphoric acid were observed as follows: Tapira (raw phosphoric acid D) > Catalão (raw phosphoric acids B and C) > Cajati (raw phosphoric acid A). The industrial purification process produces a reduction in radionuclide activity concentrations in food-grade phosphoric acid in relation to raw phosphoric acid produced in plant D and single raw phosphoric acid used in recent years. The most common use of food-grade phosphoric acid is in cola soft drinks, with an average consumption in Brazil of 72 l per person per year. Each liter of cola soft drink contains 0.5 ml of food-grade phosphoric acid, which gives an annual average intake of 36 ml of food-grade phosphoric acid per person. Under these conditions, radionuclide intake through consumption of food-grade phosphoric acid per year per person via cola soft drinks is not hazardous to human health in Brazil

  17. Electrolyte Additives for Phosphoric Acid Fuel Cells

    DEFF Research Database (Denmark)

    Gang, Xiao; Hjuler, H.A.; Olsen, C.A.

    1993-01-01

    , as a fuel-cell performance with the modified electrolytes. Specific conductivity measurements of some of the modified phosphoric acid electrolytes are reported. At a given temperature, the conductivity of the C4F9SO3K-modified electrolyte decreases with an increasing amount of the additive; the conductivity...... of the remains at the same value as the conductivity of the pure phosphoric acid. At a given composition, the conductivity of any modified electrolyte increases with temperature. We conclude that the improved cell performance for modified electrolytes is not due to any increase in conductivity.......Electrochemical characteristics of a series of modified phosphoric acid electrolytes containing fluorinated car on compounds and silicone fluids as additives are presented. When used in phosphoric acid fuel cells, the modified electrolytes improve the performance due to the enhanced oxygen...

  18. The recovery of uranium from phosphoric acid

    International Nuclear Information System (INIS)

    1989-11-01

    Phosphoric acid is an important alternative source of uranium: the world's reserves of phosphoric rock are estimated to be about 18,000 million tonnes and there are approximately 400 wet-process phosphoric acid plants in operation from which some 13,000 metric tonnes of U 3 O 8 could in principle be recovered each year. The recovery of uranium from wet-process phosphoric acid is a proven technology that is being used commercially, albeit on a limited scale because currently prevailing market conditions make it marginally economic. Nevertheless, many developing countries are interested in the recovery of uranium from phosphoric acid for use in their own nuclear power programmes. Several important reasons, such as assurance of supply, savings in foreign currency, acquisition of technology and generation of employment, may render this operation attractive in spite of the marginal economics. In view of the interest shown by several Member States, the International Atomic Energy Agency convened an Advisory Group Meeting on the Recovery of Uranium from Phosphoric Acid from 16 to 19 March 1987 with the main objectives of reviewing the current status of the technology and to suggest guidelines for the application of existing processes in developing countries. This document includes a Summary and Recommendations, followed by two review papers which discuss the current status of the technology and industrial practice of uranium recovery from phosphoric acid. Other papers discuss operating experience and current research and development work. Two Panel Discussions are also included, one on capital and operating costs and the other on guidelines for the preparation of feasibility studies. Refs, Figs and tabs

  19. Recuperation of uranium from phosphoric acid

    International Nuclear Information System (INIS)

    Cordero, G.; Jodra, L.G.; Otero, J.L.; Josa, J.M.

    1977-01-01

    The Spanish capacity for phosphoric acid production is 500.000 t P 2 O 5 /yr. This acid has an average concentration of 365 g U 3 O 8 / t P 2 O 5 . Therefore about 180 t U 3 O 8 /yr are dissolved. In 1969, the Junta de Energia Nuclear (JEN) developed, in bench scale, a solvent extraction process to recover the uranium from the phosphoric acid. The solvent used was a synergistic mixture of D2EHPA and TOPO. The results were very promising with good recovery and very high quality for the uranium concentrate. Later, the J.E.N. continued the studies in a pilot plant scale. For this purpose, was built an experimental facility in Huelva; it can treat about 7 cu. m/day of brown acid. Fosforico Espanol, S.A. (FESA) collaborated in the studies and agreed to setting up these installations in their factory. They also provided fresh phosphoric acid for the tests. In this pilot plant we studied the following stages: a) Clarification and conditioning of the phosphoric acid; b) Uranium extraction followed by stripping in a reducing medium; c) Purification by extraction and washing; d) Obtention of the concentrate by stripping with ammonia and CO 2 gas, followed by crystallization of the ammonium uranyl tricarbonate (AUT); and e) Calcination of the concentrate to decompose the AUT to uranium oxides. The results confirmed the laboratory test data. Recuperation levels were between 85 and 90%. The AUT calcined at 550 0 C. gave a product with 96-98% U 3 O 8 . In view of the pilot plant results we have prepared a black book for an industrial plant to treat about 3700 cu. m/day of phosphoric acid. At the present time the financial aspects of this installation are being studied [es

  20. Phosphoric Acid-Mediated Depolymerization and Decrystallization ...

    African Journals Online (AJOL)

    Methods: α- cellulose (AC-CC) obtained from corn cob by a delignification process, was depolymerized with 85% phosphoric acid to yield LCC-CC product, whose physical properties were compared with those of AC-CC. Results: The yield of AC-CC and LCC-CC were 14 and 11 %, respectively. The physical properties ...

  1. 40 CFR 721.6097 - Phosphoric acid derivative (generic name).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Phosphoric acid derivative (generic... Specific Chemical Substances § 721.6097 Phosphoric acid derivative (generic name). (a) Chemical substance... phosphoric acid derivative (PMN P-95-284) is subject to reporting under this section for the significant new...

  2. Uranium recovery process in phosphoric acid solutions

    International Nuclear Information System (INIS)

    Ginisty, Claude; Marteau, Michel; Mauborgne, Bernard.

    1982-01-01

    The description is given of a process for recovering uranium in a phosphoric acid solution by means of an organic solvent composed of a neutral phosphine oxide and an acid organophosphorated compound to the formulation R'R'' HPO 4 where R' and R'' which are identical or different, represent a linear or branched alkoxyalkyl radical comprising at least one -CH 2 -O-CH 2 - grouping or an aryloxyalkyl radical [fr

  3. Process for recovering a uranium containing concentrate and purified phosphoric acid from a wet process phosphoric acid containing uranium

    International Nuclear Information System (INIS)

    Weterings, C.A.M.; Janssen, J.A.

    1985-01-01

    A process is claimed for recovering from a wet process phosphoric acid which contains uranium, a uranium containing concentrate and a purified phosphoric acid. The wet process phosphoric acid is treated with a precipitant in the presence of a reducing agent and an aliphatic ketone

  4. Process for recovering a uranium containing concentrate and purified phosphoric acid from a wet process phosphoric acid containing uranium

    Energy Technology Data Exchange (ETDEWEB)

    Weterings, C.A.M.; Janssen, J.A.

    1985-04-30

    A process is claimed for recovering from a wet process phosphoric acid which contains uranium, a uranium containing concentrate and a purified phosphoric acid. The wet process phosphoric acid is treated with a precipitant in the presence of a reducing agent and an aliphatic ketone.

  5. Initiation in the study of uranium recovery from the phosphoric acid

    International Nuclear Information System (INIS)

    Anchondo Adalid, J.M.

    1974-01-01

    The loss of considerable amounts of uranium in the Mexican phosphoric acid industry makes it important to study economic methods of recovery; the studies can serve as a basis for the construction and operation of a pilot plant as a normal preliminary to larger-scale projects. Routine experimental techniques for solvent extraction were employed. Extraction efficiencies of the order of 90-95% were obtained using 0.09-0.18M solutions of a mixture of phosphoric octyl esters applied to 4 and 6M solutions of phosphoric acid (reagent grade) containing uranium in concentrations of 0.05-0.50g of U 3 O 8 per litre of acid. The conclusion was reached that phosphoric octyl esters can be used for recovering uranium in satisfactory quantities from phosphoric acid solutions by means of solvent extraction, and that the uranium can be separated from the solvent by the established procedures. (author)

  6. Uranium recovery from wet-process phosphoric acid

    International Nuclear Information System (INIS)

    McCullough, J.F.; Phillips, J.F. Jr.; Tate, L.R.

    1979-01-01

    A method of recovering uranium from wet-process phosphoric acid is claimed where the acid is treated with a mixture of an ammonium salt or ammonia, a reducing agent, and then a miscible solvent. Solids are separated from the phosphoric acid liquid phase. The solid consists of a mixture of metal phosphates and uranium. It is washed free of adhering phosphoric acid with fresh miscible solvent. The solid is dried and dissolved in acid whereupon uranium is recovered from the solution. Miscible solvent and water are distilled away from the phosphoric acid. The distillate is rectified and water discarded. All miscible solvent is recovered for recycle. 5 claims

  7. Uranium recovery from wet process phosphoric acid

    International Nuclear Information System (INIS)

    Carrington, O.F.; Pyrih, R.Z.; Rickard, R.S.

    1981-01-01

    Improvement in the process for recovering uranium from wetprocess phosphoric acid solution derived from the acidulation of uraniferous phosphate ores by the use of two ion exchange liquidliquid solvent extraction circuits in which in the first circuit (A) the uranium is reduced to the uranous form; (B) the uranous uranium is recovered by liquid-liquid solvent extraction using a mixture of mono- and di-(Alkyl-phenyl) esters of orthophosphoric acid as the ion exchange agent; and (C) the uranium oxidatively stripped from the agent with phosphoric acid containing an oxidizing agent to convert uranous to uranyl ions, and in the second circuit (D) recovering the uranyl uranium from the strip solution by liquid-liquid solvent extraction using di(2ethylhexyl)phosphoric acid in the presence of trioctylphosphine oxide as a synergist; (E) scrubbing the uranium loaded agent with water; (F) stripping the loaded agent with ammonium carbonate, and (G) calcining the formed ammonium uranyl carbonate to uranium oxide, the improvement comprising: (1) removing the organics from the raffinate of step (B) before recycling the raffinate to the wet-process plant, and returning the recovered organics to the circuit to substantially maintain the required balance between the mono and disubstituted esters; (2) using hydogren peroxide as the oxidizing agent in step (C); (3) using an alkali metal carbonate as the stripping agent in step (F) following by acidification of the strip solution with sulfuric acid; (4) using some of the acidified strip solution as the scrubbing agent in step (E) to remove phosphorus and other impurities; and (5) regenerating the alkali metal loaded agent from step (F) before recycling it to the second circuit

  8. Separation of rare earths from solutions of phosphoric acid

    International Nuclear Information System (INIS)

    Jones, E.A.

    1977-01-01

    Rare earths are separated from 6M phosphoric acid by adsorption onto cation resin BIORAD AG50W-X8. The phosphoric acid is then washed from the column, and the rare earths are eluted with 4M hydrochloric acid

  9. Acid distribution in phosphoric acid fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Okae, I.; Seya, A.; Umemoto, M. [Fuji Electric Co., Ltd., Chiba (Japan)

    1996-12-31

    Electrolyte acid distribution among each component of a cell is determined by capillary force when the cell is not in operation, but the distribution under the current load conditions had not been clear so far. Since the loss of electrolyte acid during operation is inevitable, it is necessary to store enough amount of acid in every cell. But it must be under the level of which the acid disturbs the diffusion of reactive gases. Accordingly to know the actual acid distribution during operation in a cell is very important. In this report, we carried out experiments to clarify the distribution using small single cells.

  10. Uranium recovery from wet-process phosphoric acid with octylphenyl acid phosphate. Progress report

    International Nuclear Information System (INIS)

    Arnold, W.D.; McKamey, D.R.; Baes, C.F.

    1980-01-01

    Studies were continued of a process for recovering uranium from wet-process phosphoric acid with octylphenyl acid phosphate (OPAP), a mixture of mono- and dioctylphenyl phosphoric acids. The mixture contained at least nine impurities, the principal one being octyl phenol, and also material that readily hydrolyzed to octyl phenol and orthophosphoric acid. The combination of mono- and dioctylphenyl phosphoric acids was the principal uranium extractant, but some of the impurities also extracted uranium. Hydrolysis of the extractant had little effect on uranium extraction, as did the presence of moderate concentrations of octyl phenol and trioctylphenyl phosphate. Diluent choice among refined kerosenes, naphthenic mixtures, and paraffinic hydrocarbons also had little effect on uranium extraction, but extraction was much lower when an aromatic diluent was used. Purified OPAP fractions were sparingly soluble in aliphatic hydrocarbon diluents. The solubility was increased by the presence of impurities such as octyl phenol, and by the addition of water or an acidic solution to the extractant-diluent mixture. In continuous stability tests, extractant loss by distribution to the aqueous phase was much less to wet-process phosphoric acid than to reagent grade acid. Uranium recovery from wet-process acid decreased steadily because of the combined effects of extractant poisoning and precipitation of the extractant as a complex with ferric iron. Unaccountable losses of organic phase volume occurred in the continuous tests. While attempts to recover the lost organic phase were unsuccessful, the test results indicate it was not lost by entrainment or dissolution in the phosphoric acid solutions. 21 figures, 8 tables

  11. World wide IFC phosphoric acid fuel cell implementation

    Energy Technology Data Exchange (ETDEWEB)

    King, J.M. Jr

    1996-04-01

    International Fuel Cells, a subsidary of United technologies Corporation, is engaged in research and development of all types of fuel cell technologies and currently manufactures alkaline fuel cell power plants for the U.S. manned space flight program and natural gas fueled stationary power plants using phosphoric acid fuel cells. This paper describes the phosphoric acid fuel cell power plants.

  12. Phosphor investigation in the production of Syrian phosphoric acid using Nuclear Magnetic Resonance

    International Nuclear Information System (INIS)

    Al-Hassanieh, O.; Al-Hameish, M.

    2009-06-01

    Nuclear magnetic resonance spectroscopy (NMR) was applied in this work to the industrial process of extraction of uranium from phosphoric acid and to the process of the purification of the phosphoric acid for food proposes. The structural changes of used extraction materials and the organic content of the final product was studied. 13 C , 1 H and 32 P-spectra of all material during the process were recorded. The spectra of the three used extraction materials Bis(2-ethylhexyl Phosphoric Acid)) DEHPA, TriOctyl Phosphine Oxide (TOPO) (C 8 H 1 7) 3 P=O and TriButyl Phosphate (TBP) (C 4 H 9 O) 3 P=O show a partial degradation during the process. The final product ( Phosphoric acid for Food proposes) doesn't contain any organic solvents or extraction material. (author)

  13. Process for winning uranium from wet process phosphoric acid

    International Nuclear Information System (INIS)

    1980-01-01

    A process is described for winning uranium from wet process phosphoric acid by means of liquid-liquid extraction with organic phosphoric acid esters. The process is optimised by keeping the sulphate percentage in the phosphoric acid below 2% by weight, and preferably below 0.6% by weight, as compared to P 2 O 5 in the phosphoric acid. This is achieved by adding an excess of Ba and/or Ca carbonate or sulfide solution and filtering off the formed calcium and/or barium sulphate precipitates. Solid KClO 3 is then added to the filtrate to oxidise U 4+ to U 6+ . The normal extraction procedure using organic phosphoric esters as extraction liquid, can then be applied. (Th.P.)

  14. New applications for phosphoric acid fuel cells

    Science.gov (United States)

    Stickles, R. P.; Breuer, C. T.

    1983-11-01

    New applications for phosphoric acid fuel cells were identified and evaluated. Candidates considered included all possibilities except grid connected electric utility applications, on site total energy systems, industrial cogeneration, opportunistic use of waste hydrogen, space and military applications, and applications smaller than 10 kW. Applications identified were screened, with the most promising subjected to technical and economic evaluation using a fuel cell and conventional power system data base developed in the study. The most promising applications appear to be the underground mine locomotive and the railroad locomotive. Also interesting are power for robotic submersibles and Arctic villages. The mine locomotive is particularly attractive since it is expected that the fuel cell could command a very high price and still be competitive with the conventionally used battery system. The railroad locomotive's attractiveness results from the (smaller) premium price which the fuel cell could command over the conventional diesel electric system based on its superior fuel efficiency, and on the large size of this market and the accompanying opportunities for manufacturing economy.

  15. Probing phosphoric acid redistribution and anion migration in polybenzimidazole membranes

    DEFF Research Database (Denmark)

    Becker, Hans; Cleemann, Lars Nilausen; Aili, David

    2017-01-01

    Micro platinum electrodes embedded in a laminated phosphoric acid doped polybenzimidazole membrane are employed to monitor the acid migration during hydrogen pump mode operation. Upon application of a constant current, an immediate ohmic resistance decrease of the membrane near the anode is obser......Micro platinum electrodes embedded in a laminated phosphoric acid doped polybenzimidazole membrane are employed to monitor the acid migration during hydrogen pump mode operation. Upon application of a constant current, an immediate ohmic resistance decrease of the membrane near the anode...... mechanism e.g. for determination of the anionic transference number. The finding provides a technique to monitor the acid redistribution within the membrane as a basis for an engineering solution to address the long-term durability of fuel cells built around phosphoric acid doped polymer membranes....

  16. Process for recovery of uranium from wet process phosphoric acid

    International Nuclear Information System (INIS)

    Wiewiorowski, T.K.; Thornsberry, W.L. Jr.

    1978-01-01

    Process is claimed for the recovery of uranium from wet process phosphoric acid solution in which an organic extractant, containing uranium values and dissolved iron impurities and comprising a dialkylphosphoric acid and a trialkylphosphine oxide dissolved in a water immiscible organic solvent, is contacted with a substantially iron-free dilute aqueous phosphoric acid to remove said iron impurities. The removed impurities are bled from the system by feeding the resulting iron-loaded phosphoric acid to a secondary countercurrent uranium extraction operation from which they leave as part of the uranium-depleted acid raffinate. Also, process for recovering uranium in which the extractant, after it has been stripped of uranium values by aqueous ammonium carbonate, is contacted with a dilute aqueous acid selected from the group consisting of H 2 SO 4 , HCl, HNO 3 and iron-free H 3 PO 4 to improve the extraction efficiency of the organic extractant

  17. Uranium extraction process from phosphoric acid by alkyl pyrophosphoric acid

    International Nuclear Information System (INIS)

    Floreancig, A.

    1984-01-01

    In this process the phosphoric acid is contacted, under stirring with the organic phase containing the extracting agent to form an emulsion. The extraction unit comprises n stages in cascade, in each stage an emulsion is produced in a first step by an intense shearing action on the two phases during a time T 1 corresponding to a shear coefficient of at least 5000 s -1 aiming at the multiplication of contact surface between the two phases, in a second step the emulsion is rapidly broken in a time T 2 , the total time required by the 2 steps is no more than 20 minutes [fr

  18. Purification of the phosphoric acid from Itataia, state of Ceara, BR: removal of thorium and other chemicals species

    International Nuclear Information System (INIS)

    Fukuma, Henrique Takuji

    2004-02-01

    operational conditions, showed that the process of extraction removed the thorium and others impurities contained in the phosphoric acid. The promoted purification can convert the phosphoric acid to technical grade, aggregating commercial values. Additionally, the proposed solvent extraction process will supply phosphoric acid with adequate specification to be used in the uranium solvent extraction unit as a tool to reduce the contaminant levels. This reduction will allow the final uranium concentrate to attending the specifications of chemical impurities imposed by nuclear fuel cycle. Consequently, the phosphoric acid purification might supply such needs avoiding the acquisition of this product from other manufacturers, but which would increase the transport costs. (author)

  19. Cadmium elemination from phosphoric acid by ionic flotation

    International Nuclear Information System (INIS)

    Brikci-Nigassa, Mounir; Hamouche, Hafida

    1995-11-01

    The ion flotation process for the recovery of cadmium from wet phosphoric acid (30%P2O5) has been studied. This technique combines a chemical recation between the collector and the cadmium to form a precipitate (sublate) which is carried to the surface of the solution by air bubbles. the resulting foam containing the cadmium may then separated from solution. The influence of parameters such as collector and cadmium concentration as well as iron content have been investigated for the case a synthetic acid (30% P2O5). The result have been applied to the industrial phosphoric acid produced from Djebel Onk's phosphates (Algeria)

  20. Method for recovery of uranium from phosphoric acid

    International Nuclear Information System (INIS)

    Duarte Neto, J.

    1984-01-01

    The results of a method for recuperation of uranium from phosphoric acid by humid way are presented. The extracting mixture used was di-ethylhexylphosphoric acid (D 2 EHPA) and trioctylphosphine oxide (TOPO). An installation in micro-pilot scale was made to get and visualize data for continuous process. (M.A.C.) [pt

  1. Phosphors

    International Nuclear Information System (INIS)

    1975-01-01

    This invention relates to phosphors that can be used in fluorescent lamps and display devices. The phosphor is comprised of a halophosphate of calcium and/or strontium of apatite crystal structure activated with trivalent cerium and trivalent terbium. The phosphor can further include manganese. Preferably, the phosphor includes up to 10% by weight of one or more of the alkali metals lithium, sodium and potassium in the form of a compound or compounds thereof. The emissions appear as a number of fairly narrow discrete bands. The temperature of preparation is 1000degC (as opposed to the usual 1450degC), therefore reducing costs (less energy is needed, more crucibles are readily obtainable and there is no need for special conditions to enable crucibles to overcome thermal shock)

  2. Phosphoric acid fuel cell R and D activities at KACST

    International Nuclear Information System (INIS)

    Ghouse, M.; Aba-Oud, H.; Ba-Junaid, M.; Al-Garni, M.; Quadri, M.I.

    1993-01-01

    The PAFC (Phosphoric Acid Fuel Cell) activities are directed towards the development of components of single cell and experimental stacks at KACST. The main aim of the present task is to design and construct a 1 kW PAFC Stack and demonstrate it by integrating with an electrolyser using a DC current generated by a photovoltaic power source. This paper describes the preparation of porous teflon bonded gas diffusion carbon electrodes and their evaluation as single phosphoric acid fuel cells using hydrogen as a fuel and oxygen/air as an oxidant. 6 figs., 2 tabs., 15 refs

  3. Purification of di-nonyl phenyl phosphoric acid (DNPPA) for synergistic extraction of uranium from strong phosphoric acid

    International Nuclear Information System (INIS)

    Singh, D.K.; Vijayalakshmi, R.; Singh, H.; Sharma, J.N.; Ruhela, R.

    2009-01-01

    Di-nonyl phenyl phosphoric acid (DNPPA) obtained from various synthesis methods is always associated with impurities such as mono-nonyl phenyl phosphoric acid and nonyl phenol which need to be separated for its effective use in the extraction of uranium from strong phosphoric acid. Two methods of purification namely liquid-solid separation method using neodymium salt and liquid-liquid separation method using methylene glycol have been described. In the liquid solid separation method the purity of DNPPA obtained was about 95% with less than 1.0% monoester, however it heavily suffers in the recovery aspect which is of the order of 50-60%. The methylene glycol treatment method, results in high purity and recovery of the product. Purity obtained was about 95.0% diester and less than 0.5% monoester and recovery was more than 90%. Analysis of DNPPA was done by potentiometric titration method using autotitrator. (author)

  4. Solid-state actinide acid phosphites from phosphorous acid melts

    International Nuclear Information System (INIS)

    Oh, George N.; Burns, Peter C.

    2014-01-01

    The reaction of UO 3 and H 3 PO 3 at 100 °C and subsequent reaction with dimethylformamide (DMF) produces crystals of the compound (NH 2 (CH 3 ) 2 )[UO 2 (HPO 2 OH)(HPO 3 )]. This compound crystallizes in space group P2 1 /n and consists of layers of uranyl pentagonal bipyramids that share equatorial vertices with phosphite units, separated by dimethylammonium. In contrast, the reaction of phosphorous acid and actinide oxides at 210 °C produces a viscous syrup. Subsequent dilution in solvents and use of standard solution-state methods results in the crystallization of two polymorphs of the actinide acid phosphites An(HPO 2 OH) 4 (An=U, Th) and of the mixed acid phosphite–phosphite U(HPO 3 )(HPO 2 OH) 2 (H 2 O)·2(H 2 O). α- and β-An(HPO 2 OH) 4 crystallize in space groups C2/c and P2 1 /n, respectively, and comprise a three-dimensional network of An 4+ cations in square antiprismatic coordination corner-sharing with protonated phosphite units, whereas U(HPO 3 )(HPO 2 OH) 2 (H 2 O) 2 ·(H 2 O) crystallizes in a layered structure in space group Pbca that is composed of An 4+ cations in square antiprismatic coordination corner-sharing with protonated phosphites and water ligands. We discuss our findings in using solid inorganic reagents to produce a solution-workable precursor from which solid-state compounds can be crystallized. - Graphical abstract: Reaction of UO 3 and H 3 PO 3 at 100 °C and subsequent reaction with DMF produces crystals of (NH 2 (CH 3 ) 2 )[UO 2 (HPO 2 OH)(HPO 3 )] with a layered structure. Reaction of phosphorous acid and actinide oxides at 210 °C produces a viscous syrup and further solution-state reactions result in the crystallization of the actinide acid phosphites An(HPO 2 OH) 4 (An=U, Th), with a three-dimensional network structure, and the mixed acid phosphite–phosphite U(HPO 3 )(HPO 2 OH) 2 (H 2 O) 2 ·(H 2 O) with a layered structure. - Highlights: • U(VI), U(IV) and Th(IV) phosphites were synthesized by solution

  5. The Electrochemical Behavior of Phosphoric-Acid-Doped Poly(perfluorosulfonic Acid) Membranes

    DEFF Research Database (Denmark)

    Aili, David; Savinell, Robert F; Jensen, Jens Oluf

    2014-01-01

    Highly conductive phosphoric-acid-doped poly(perfluorosulfonic acid) membranes have long been known to malfunction in fuel cells. This is investigated and found to be due to failure of the anode, in which a limiting current is observed in the very low current-density range. It is proposed...... that the strongly acidic sulfonic acid groups protonate the phosphoric acid under anhydrous conditions, forming excess proton defects that are involved in proton conduction by means of the vehicle mechanism. The slow back-diffusion of phosphoric acid molecules as proton carriers thus limits the long...

  6. Fluoride removal performance of phosphoric acid treated lime ...

    African Journals Online (AJOL)

    Fluoride in drinking water above permissible levels is responsible for dental and skeletal fluorosis. In this study, removal of fluoride ions from water using phosphoric acid treated lime was investigated in continuous and point-of-use system operations. In the continuous column operations, fluoride removal performance was ...

  7. Fluoride removal performance of phosphoric acid treated lime ...

    African Journals Online (AJOL)

    2010-11-25

    Nov 25, 2010 ... Fluoride in drinking water above permissible levels is responsible for dental and skeletal fluorosis. In this study, removal of fluoride ions from water using phosphoric acid treated lime was investigated in continuous and point-of-use system opera- tions. In the continuous column operations, fluoride removal ...

  8. Natural Radiation in byproducts of the production of phosphoric acid

    International Nuclear Information System (INIS)

    Silveira, Marcilei A. Guazzelli da; Cardoso, L.L.; Medina, N.H.

    2014-01-01

    Natural radiation is the largest source of radiation exposure to which man is subject. It is formed basically by cosmic radiation and the radionuclides present in the Earth crust, as 40 K and the elements of the decay series of 232 Th and 238 U. Phosphate ores, which constitutes the raw material for the production of phosphoric acid, have a high rate of natural radiation from the decay series of 232 Th and 238 U. Phosphogypsum, which is naturally radioactivity, is a by-product of the production of phosphoric acid by the wet method. For each ton of phosphoric acid it is produced about 4.5 tons of phosphogypsum. This work presents the analysis of samples collected in all stages of the manufacturing process of phosphoric acid, which generates the phosphogypsum. Gamma-ray spectrometry was used to measure the concentration of the elements of the decay series of 232 Th and 238 U. All analyzed samples showed a high concentration of radionuclides, promoting the need for further steps in the process in order to reduce the presence of such radionuclides in the phosphogypsum. The results indicate the radionuclide 238 U has higher contribution in some samples of the intermediate stages of the process. All samples exceeded the international average range of human exposure to terrestrial gamma radiation, which is 0.3 to 1.0 mSv/year. (author)

  9. Process for recovering yttrium and lanthanides from wet-process phosphoric acid

    Energy Technology Data Exchange (ETDEWEB)

    Janssen, J.A.; Weterings, C.A.

    1983-06-28

    Process for recovering yttrium and lanthanides from wet-process phosphoric acid by adding a flocculant to the phosphoric acid, separating out the resultant precipitate and then recovering yttrium and lanthanides from the precipitate. Uranium is recovered from the remaining phosphoric acid.

  10. Solid-state actinide acid phosphites from phosphorous acid melts

    Energy Technology Data Exchange (ETDEWEB)

    Oh, George N. [Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, 156 Fitzpatrick Hall, Notre Dame, IN 46556 (United States); Burns, Peter C., E-mail: pburns@nd.edu [Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, 156 Fitzpatrick Hall, Notre Dame, IN 46556 (United States); Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556 (United States)

    2014-07-01

    The reaction of UO{sub 3} and H{sub 3}PO{sub 3} at 100 °C and subsequent reaction with dimethylformamide (DMF) produces crystals of the compound (NH{sub 2}(CH{sub 3}){sub 2})[UO{sub 2}(HPO{sub 2}OH)(HPO{sub 3})]. This compound crystallizes in space group P2{sub 1}/n and consists of layers of uranyl pentagonal bipyramids that share equatorial vertices with phosphite units, separated by dimethylammonium. In contrast, the reaction of phosphorous acid and actinide oxides at 210 °C produces a viscous syrup. Subsequent dilution in solvents and use of standard solution-state methods results in the crystallization of two polymorphs of the actinide acid phosphites An(HPO{sub 2}OH){sub 4} (An=U, Th) and of the mixed acid phosphite–phosphite U(HPO{sub 3})(HPO{sub 2}OH){sub 2}(H{sub 2}O)·2(H{sub 2}O). α- and β-An(HPO{sub 2}OH){sub 4} crystallize in space groups C2/c and P2{sub 1}/n, respectively, and comprise a three-dimensional network of An{sup 4+} cations in square antiprismatic coordination corner-sharing with protonated phosphite units, whereas U(HPO{sub 3})(HPO{sub 2}OH){sub 2}(H{sub 2}O){sub 2}·(H{sub 2}O) crystallizes in a layered structure in space group Pbca that is composed of An{sup 4+} cations in square antiprismatic coordination corner-sharing with protonated phosphites and water ligands. We discuss our findings in using solid inorganic reagents to produce a solution-workable precursor from which solid-state compounds can be crystallized. - Graphical abstract: Reaction of UO{sub 3} and H{sub 3}PO{sub 3} at 100 °C and subsequent reaction with DMF produces crystals of (NH{sub 2}(CH{sub 3}){sub 2})[UO{sub 2}(HPO{sub 2}OH)(HPO{sub 3})] with a layered structure. Reaction of phosphorous acid and actinide oxides at 210 °C produces a viscous syrup and further solution-state reactions result in the crystallization of the actinide acid phosphites An(HPO{sub 2}OH){sub 4} (An=U, Th), with a three-dimensional network structure, and the mixed acid phosphite

  11. Investigation of the synergic effect of some neutral organophosphoric compounds on the extraction of uranium from phosphoric acid solutions by D1-(2-Ethyl Hexyl) phosphoric acid

    International Nuclear Information System (INIS)

    Stas, J.; Khorfan, S.; Koudsi, Y.

    1998-05-01

    The extraction of uranium (VI) from pure phosphoric acid media by D2EHPA/Kerosene has been studied. The mechanism of the extraction was found as follows: The logarithm of the equilibrium constant of the extraction (LogKex) was found (3.06), (3.32), (3.24), (3.3) for the following phosphoric acid concentrations respectively (1), (2), (3), (4) Mol/1, and the enthalpy change DELTA H was found (-100.68 kj/mol). (-76 kj/mol) for (1), (2) mol/1 phosphoric acid concentrations. The synergic effect of TOPO, TBP, and TBPI with DEHPA have been studied during the extraction of uranium from pure phosphoric acid and Syrian commercial phosphoric acid. The synergic effect increases as follows: TBP< TBPI<< TOPO (In pure phosphoric acid), TBPI approx TBP<< TOPO (In Syrian commercial phosphoric acid). The difficulty of extracting uranium (VI) from Syrian commercial phosphoric acid in comparison with pure phosphoric acid is due to the presence of several impurities capable of complexing uranium, and a small amounts of solid and organic matters, all these are factors which reduce the distribution coefficient of uranium. (Author)

  12. Solid-state actinide acid phosphites from phosphorous acid melts

    Energy Technology Data Exchange (ETDEWEB)

    Oh, George N.; Burns, Peter C.

    2014-07-01

    The reaction of UO3 and H3PO3 at 100 °C and subsequent reaction with dimethylformamide (DMF) produces crystals of the compound (NH2(CH3)2)[UO2(HPO2OH)(HPO3)]. This compound crystallizes in space group P21/n and consists of layers of uranyl pentagonal bipyramids that share equatorial vertices with phosphite units, separated by dimethylammonium. In contrast, the reaction of phosphorous acid and actinide oxides at 210 °C produces a viscous syrup. Subsequent dilution in solvents and use of standard solution-state methods results in the crystallization of two polymorphs of the actinide acid phosphites An(HPO2OH)4 (An=U, Th) and of the mixed acid phosphite–phosphite U(HPO3)(HPO2OH)2(H2O)·2(H2O). α- and β-An(HPO2OH)4 crystallize in space groups C2/c and P21/n, respectively, and comprise a three-dimensional network of An4+ cations in square antiprismatic coordination corner-sharing with protonated phosphite units, whereas U(HPO3)(HPO2OH)2(H2O)2·(H2O) crystallizes in a layered structure in space group Pbca that is composed of An4+ cations in square antiprismatic coordination corner-sharing with protonated phosphites and water ligands. We discuss our findings in using solid inorganic reagents to produce a solution-workable precursor from which solid-state compounds can be crystallized.

  13. Kinetic study of ion exchange in phosphoric acid chelating resin

    International Nuclear Information System (INIS)

    Brikci-Nigassa, Mounir; Hamouche, Hafida

    1995-11-01

    Uranium may be recovered as a by product of wet phosphoric acid using a method based on specific ion exchange resins. These resins called chelates contain amino-phosphonic functional groups. The resin studied in this work is a purolite S-940; uranium may be loaded on this resin from 30% P2O5 phosphoric acid in its reduced state. The influence of different parameters on the successive steps of the process have been studied in batch experiments: uranium reduction, loading and oxydation. Uranium may be eluted with ammonium carbonate and the resin regeneration may be done with hydrochloric acid.Ferric ions reduce the effective resin capacity considerably and inert fixation conditions are proposed to enhance uranium loading

  14. Corrosion rate of construction materials in hot phosphoric acid with the contribution of anodic polarization

    DEFF Research Database (Denmark)

    Kouril, M.; Christensen, Erik; Eriksen, S.

    2011-01-01

    ). Several grades of stainless steels were tested as well as tantalum, niobium, titanium, nickel alloys and silicon carbide. The corrosion rate was evaluated by means of mass loss at free corrosion potential as well as under various levels of polarization. The only corrosion resistant material in 85...... to tantalum, titanium is free of any corrosion resistance in hot phosphoric acid. Its corrosion rate ranges from tens of millimetres to metres per year depending on temperature of the acid. Alloy bonded tantalum coating was recognized as an effective corrosion protection for both titanium and stainless steel...

  15. EXERGETIC OPTIMIZATION OF PHOSPHORIC ACID FACTORY POWER PLANT

    OpenAIRE

    Tahar, Khir

    2017-01-01

    AnEnergetic and Exergetic Analysis is conducted on a Steam Turbine Power Plant ofan existing Phosphoric Acid Factory. The heat recovery systems used indifferent parts of the plant are also considered in the analysis. Mass, thermaland exergy balances are established on the main components of the factory. Anumerical code is established using EES software to perform the calculationsrequired for the thermal and exergy plant analysis. The effects of the keyoperating parameters such as steam pressu...

  16. Synthesis and complex forming property of phosphor acid derivatives

    International Nuclear Information System (INIS)

    Babaev, B.N.

    2004-01-01

    Full text:With the aim to get new effective and selective extra gents of noble and non-ferrous metals from acid solution and industrial sewage, research of the dependence of 'structure effectiveness' the various phosphor acid derivatives with logical changeable structure (thio phosphor acids, derivatives of dialkoxythiophosphor, O-alkyl-methylphosphon, alkylphenylphosphon, diphenylphosphine acids also 4 methyl-1,3,2 dioxaphosphorinane) which contain different functional groups, the remains of heterocyclic amines and alkaloids, new derivatives of some analytical reagents were synthesized. The structure of synthesized compounds is approved by the results of IR-, PMR-, mass-spectrum analyze. Researching mass-spectrum decay of synthesized phosphor acid derivatives we defined that differing from O-dihexyl-S-propargyl-benzylthio phosphat, mass spectrum decay of O-dialkyl-S-(piperdynobutin-2-il)thio phosphat is characterized by the appearing [M-H] + ions and during the decay ions with high intensiveness are formed. Fragmentation of M + O-alkyl-O-(aminoalkyl)phenylphosphonate proceeds in various directions and characterized with the great number of phosphor containing ions, the possession of the second phenyl radical in the molecule of diphenylphosphon acid derivatives changes the fragmentation of molecular ion of diphenylphosphon acid derivatives. The process of extraction of noble (Au, Ag, Pt, Pd, Os) metals from hydrochloric-sulphur-nitrogen acid medium was analyzed by radioactive indicator's method. It was noticed that structure, strength, conformation of compounds, the temperature, of acid medium (0,1-10 M) and the nature of acids (HCL, H 2 SO 4 , HNO 3 ) could have strong influence to the effectiveness of metal extraction. During the research of metals extraction from pure solutions we can see the followings: 1) There are such substances, which can be used as effective group reagent towards the Au, Ag and Pd. 2) Derivatives with acetylene extract ions of gold from

  17. The recovery of uranium from wet process phosphoric acid

    International Nuclear Information System (INIS)

    Francois, A.; Sialino, A.

    1981-01-01

    A process for the recovery of uranium from a wet-process phosphoric acid is claimed. The preliminary oxidized acid is treated first with an organic solvent consisting of a dialkylphosphoric acid and a trialkylphosphine oxide, dissolved in an inert and unreactive organic solvent in order to obtain uranium-free phosphoric acid and an organic extract consisting of the solvent containing the major portion of uranium. The uranium is separated from the extract as ammonium uranyl tricarbonate by reacting with ammonium hydroxide and ammonium carbonate and the uranium-free solvent is recycled to the extraction step. The extract is treated in a re-extraction apparatus having at least two stages: the extract is introduced at the head of the first stage and ammonia or ammonium hydroxide solution at the bottom. The pH of the first stage is maintained in the range 8.0 to 8.5. An ammonium carbonate aqueous solution is introduced at the bottom of the last stage. The amount of ammonium carbonate used is equal to 50 to 80 percent by weight of the theoretical molar quantity which is necessary to neutralize the dialkylphosphoric acid contained in the solvent and convert the uranium in ammonium uranyl tricarbonate. The ammoniated solvent obtained after the re-extraction step is regenerated by treatment with an acid before recycling it to the extraction step

  18. Process for recovering uranium from wet process phosphoric acid (III)

    International Nuclear Information System (INIS)

    Pyrih, R.Z.; Rickard, R.S.; Carrington, O.F.

    1983-01-01

    Uranium is conventionally recovered from wet-process phosphoric acid by two liquid ion exchange steps using a mixture of mono- and disubstituted phenyl esters of orthophosphoric acid (OPPA). Efficiency of the process drops as the mono-OPPA is lost preferentially to the aqueous phase. This invention provides a process for the removal of the uranium process organics (OPPA and organic solvents) from the raffinate of the first liquid ion exchange step and their return to the circuit. The process organics are removed by a combination flotation and absorption step, which results in the recovery of the organics on beads of a hydrophobic styrene polymer

  19. Process for extracting uranium from phosphoric acid solutions

    International Nuclear Information System (INIS)

    1977-01-01

    The description is given of a method for extracting uranium from phosphoric acid solutions whereby the previously oxided acid is treated with an organic solvent constituted by a mixture of dialkylphosphoric acid and trialkylphosphine oxide in solution in a non-reactive inert solvent so as to obtain de-uraniated phosphoric acid and an organic extract constituted by the solvent containing most of the uranium. The uranium is then separated from the extract as uranyl ammonium tricarbonate by reaction with ammonia and ammonium carbonate and the extract de-uraniated at the extraction stage is recycled. The extract is treated in a re-extraction apparatus comprising not less than two stages. The extract to be treated is injected at the top of the first stage. At the bottom of the first stage, ammonia is introduced counter current as gas or as an aqueous solution whilst controlling the pH of the first stage so as to keep it to 8.0 or 8.5 and at the bottom of the last stage an ammonium carbonate aqueous solution is injected in a quantity representing 50 to 80% of the stoichiometric quantity required to neutralize the dialkylphosphoric acid contained in the solvent and transform the uranium into uranyl ammonium tricarbonate [fr

  20. Ionic flotation of uranium contained in industrial phosphoric acid

    International Nuclear Information System (INIS)

    Jdid; Blazy; Bessiere

    1983-01-01

    A new process for uranium recovery from industrial phosphoric acid at 30% of P 2 O 5 is applied by the ionic flotation process. Research is carried out on determination of the nature of ionic species of U in H 3 PO 4 5.5 M and the behavior of reagents from CECA Co. in very acid media. Reagents able to form complexes directly with uranium and stable in phosphoric acid selected are: potassium ethylene diamine tetra (methylene phosphonate) (INIPOL AD32) and sodium dialkyldiphosphonate (34S). Uranium IV, obtained by reduction of uranium VI with iron powder, is precipitated by these reagents. Flotation of the precipitate obtained with INIPOL AD 32 is realized by addition of hexylamino bis (methylene phosphonic acid). A recovery of 80 wt% is obtained. Flotation of the coprecipitate 34S-U(IV) is obtained without any other additions because 34S is a surfactant. Metal recovery is better than 90% and the coprecipitate contains more than 10% U. The process is fast precipitation 10 minutes and flotation 5 minutes and is efficient even at 60 0 C [fr

  1. Nitric-phosphoric acid oxidation of organic waste materials

    International Nuclear Information System (INIS)

    Pierce, R.A.; Smith, J.R.

    1995-01-01

    A wet chemical oxidation technology has been developed to address issues facing defense-related facilities, private industry, and small-volume generators such as university and medical laboratories. Initially tested to destroy and decontaminate a heterogenous mixture of radioactive-contaminated solid waste, the technology can also remediate other hazardous waste forms. The process, unique to Savannah River, offers a valuable alternative to incineration and other high-temperature or high-pressure oxidation processes. The process uses nitric acid in phosphoric acid; phosphoric acid allows nitric acid to be retained in solution well above its normal boiling point. The reaction converts organics to carbon dioxide and water, and generates NO x vapors which can be recycled using air and water. Oxidation is complete in one to three hours. In previous studies, many organic compounds were completely oxidized, within experimental error, at atmospheric pressure below 180 degrees C; more stable compounds were decomposed at 200 degrees C and 170 kPa. Recent studies have evaluated processing parameters and potential throughputs for three primary compounds: EDTA, polyethylene, and cellulose. The study of polyvinylchloride oxidation is incomplete at this time

  2. Absorption characteristics of Kupravas deposit clays modified by phosphoric acid

    International Nuclear Information System (INIS)

    Ruplis, A.; Mezinskis, G.; Chaghuri, M.

    1998-01-01

    Literature data suggested that clays may be used as sorbents for waste water treatment. The surface and sorption properties of minerals changes due to the influence of acid rains. The process of recession of clay properties has been modeled in laboratory by treatment of clays with mineral acids at higher temperature that in natural conditions. The present paper is devoted to the study of influence of phosphoric acid on the sorption properties of Kupravas deposit clays. Natural clay samples and samples treated with phosphoric acid were characterized by means of x-ray diffraction an differential thermal analysis (DTA) methods These methods were used also to identify the sample of Lebanese clays. X-ray diffraction analysis data show that the samples of clays from the deposit of Kuprava contain illite and kaolinite while sample of Lebanese clay contains quartz, calcite, and montmorillonite. DTA results show characteristic features of Kuprava clays described in reference with DTA of Lebanese clay clearly demonstrate the presence of large quantity of calcite

  3. The optimisation study of tbp synthesis process by phosphoric acid

    International Nuclear Information System (INIS)

    Amedjkouh, A.; Attou, M.; Azzouz, A.; Zaoui, B.

    1995-07-01

    The present work deals with the optimisation study of TBP synthesis process by phosphoric acid. This way of synthesis is more advantageous than POCL3 or P2O5 as phosphatant agents. these latters are toxic and dangerous for the environnement. The optimisation study is based on a series of 16 experiences taking into account the range of variation of the following parameters : temperature, pressure, reagents mole ratio, promoter content. the yield calculation is based on the randomisation of an equation including all parameters. the resolution of this equation gave a 30% TBP molar ratio. this value is in agreement with that of experimental data

  4. Alternative processes for uranium recovery from phosphoric acid

    International Nuclear Information System (INIS)

    Duarte Neto, J.; Santos Benedetto, J. dos; Aquino, J.A. de.

    1987-01-01

    Two processes of solvent extraction using D 2 EHPATOPO synergistic mixture, in order to recover uranium from phosphoric acid proceeding from physical and chemical treatments of the phosphorus-uraniferous ore of Itataia-CE, Brazil, are studied. The steps of each process were studied in laboratory and pilot scales. The flow charts for both processes with detailed description of each step, the operational conditions, the mass balances, the results obtained and the description of pilot units, are presented. (M.C.K.) [pt

  5. A process for uranium recovery in phosphoric acid

    International Nuclear Information System (INIS)

    Duarte Neto, J.

    1984-01-01

    Results are presented about studies carried out envisaging the development of a process for uranium recovery from phosphoric acid, produced from the concentrate obtained from phosphorus-uraniferous mineral from Itataia mines (CE, Brazil). This process uses a mixture of DEPA-TOPO as extractant and the extraction cycle involves the following stages: acid pre-treatment; adjustment of the oxidation potential so to ensure that all uranium is hexavalent; extraction of uranium from the acid; screening of the solvent to remove undesirable impurities; uranium re-extraction and precipitation; solvent recovery. A micro-pilot plant for continuous processing was built up. Data collected showed that uranium can be recovered with an yield greater than 99%, thus proving the feasibility of the process and encouraging the construction of a bigger scale plant. (Author) [pt

  6. Complexity in Acid?Base Titrations: Multimer Formation Between Phosphoric Acids and Imines

    OpenAIRE

    Malm, Christian; Kim, Heejae; Wagner, Manfred; Hunger, Johannes

    2017-01-01

    Abstract Solutions of Br?nsted acids with bases in aprotic solvents are not only common model systems to study the fundamentals of proton transfer pathways but are also highly relevant to Br?nsted acid catalysis. Despite their importance the light nature of the proton makes characterization of acid?base aggregates challenging. Here, we track such acid?base interactions over a broad range of relative compositions between diphenyl phosphoric acid and the base quinaldine in dichloromethane, by u...

  7. Radiotracer investigation of phosphoric acid and phosphatic fertilizers production process

    International Nuclear Information System (INIS)

    Ben Abdelouahed, H.; Reguigui, N.

    2011-01-01

    In the phosphoric acid production process, the time a particle spends inside the chemical reactor (residence time) is of paramount importance to process engineers. Residence time distribution (RTD) gives information on the efficiency of the chemical reactor, on the efficiency of the process, and also the availabilities of the reactive volume for the reaction (active volume vs. dead volume). Traditionally, chemical engineers used chemical tracer to determine the RTD. However, first disadvantage is that the chemical tracer could not allow an online diagnosis: the samples containing chemical tracer have to go to a lab for analysis, second disadvantage is that the chemical tracer is less sensitive than radioactive ones because of its adsorption onto strata or its retention in rocks. Consequently, chemical tracer results are not always precise and cannot convincingly explain the multiple flow-path model. Radioactive tracers are the only tracers capable of measuring the active RTD with high degree of precision and give information on the internal recirculation rate. In this work, we will describe the application of radiotracer method for RTD measurement in the phosphoric acid production process and give results and discussion of each case encountered. (author)

  8. Enamel structural changes induced by hydrochloric and phosphoric acid treatment.

    Science.gov (United States)

    Bertacci, Angelica; Lucchese, Alessandra; Taddei, Paola; Gherlone, Enrico F; Chersoni, Stefano

    2014-12-30

    The aim of this study was to evaluate enamel acid-induced structural changes after 2 different treatments, by means of Raman and infrared (IR) spectroscopy analyses, and to correlate these findings with permeability measured as fluid discharge from outer enamel. Two different treatments were investigated: 10 enamel slices were etched with 15% hydrochloric acid (HCl) for 120 seconds and 10 slices with 37% phosphoric acid gel (H3PO4) for 30 seconds, rinsed for 30 seconds and then air-dried for 20 seconds. Powders of enamel treated as previously described were produced. Replicas of enamel subjected to the same treatments were obtained to evaluate the presence of fluid droplets on enamel surface. Raman and IR spectroscopy showed that the treatment with both hydrochloric and phosphoric acids induced a decrease in the carbonate content of the enamel apatite. At the same time, both acids induced the formation of HPO42- ions. After H3PO4 treatment, the bands due to the organic component of enamel decreased in intensity, while they increased after HCl treatment. Replicas of H3PO4 treated enamel showed a strongly reduced permeability. Replicas of HCl 15% treated samples showed a maintained permeability. A decrease of the enamel organic component, as resulted after H3PO4 treatment, involves a decrease in enamel permeability, while the increase of the organic matter (achieved by HCl treatment) still maintains enamel permeability.The results suggested a correlation between organic matter and enamel permeability. Permeability was affected by etching technique and could be involved in marginal seal, gap and discoloration at the enamel interface, still causes of restoration failure.

  9. Online Automatic Titration of Chromic Acid in Chromium Plating Solutions and Phosphoric and Sulfuric Acids in Electropolishing Solutions

    National Research Council Canada - National Science Library

    Sopok, Samuel

    1991-01-01

    .... The analytical chemistry literature lacks an adequate online automatic titration method for the monitoring of chromic acid in chromium plating solutions and the monitoring of phosphoric and sulfuric...

  10. Process for the winning of a concentrate containing uranium and purified phosphoric acid, as well as the concentrate containing uranium and purified phosphoric acid obtained by this process

    International Nuclear Information System (INIS)

    1980-01-01

    The uranium containing concentrate and purified phosphoric acid are obtained by treating wet phosphoric acid with an inorganic fluorine compound (ammonium fluoride) and an aliphatic ketone (acetone) in the presence of a reducing agent (finely divided iron). The ketone is added first and the formed uranium precipitate is separated from the solution. If the fluorine compound is added first, the yield is lowered by a factor of 2. (Th.P.)

  11. Study of the mechanism and kinetics of the reduction of uranyl ions in phosphoric acid solutions

    International Nuclear Information System (INIS)

    El Kacemi, K.; Tyburce, B.; Belcadi, S.

    1982-01-01

    The electrochemical reduction of uranyl ions in 0.1 to 9 M phosphoric acid has been investigated by polarography, cyclic voltammetry, chronopotentiometry and potentiostatic coulometry. In concentrated phosphoric acid solutions (H 3 PO 4 3 PO 4 concentrations. So, when the concentration of U(VI) increases and/or that of H 3 PO 4 reduces, the system becomes reversible. (author)

  12. Influence of concentration in phosphoric acid treatment of titanium oxide and their powder properties

    Directory of Open Access Journals (Sweden)

    Hiroaki Onoda

    2015-03-01

    Full Text Available Titanium oxide that has the photocatalytic activity is used as a white pigment for cosmetics. A certain degree of sebum on the skin is decomposed by the ultraviolet radiation in sunlight. In this work, titanium oxide was shaken with various concentrations of phosphoric acid to synthesize a novel white pigment for cosmetics. Their chemical composition, powder properties, photocatalytic activity, color phase, and smoothness were studied. The obtained materials indicated XRD peaks of titanium oxide; however, these peak intensities became weak by phosphoric acid treatment. The photocatalytic activity of the obtained powders became weak by phosphoric acid treatment to protect the sebum on the skin. The high concentration of phosphoric acid was suitable to obtain a novel white pigment in the phosphoric acid treatment of titanium oxide.

  13. Application of a precipitation method for uranium recovery from Abu-Zaabal phosphoric acid plant, egypt

    International Nuclear Information System (INIS)

    El-Hazek, N.M.T.; Hussein, E.M.

    1997-01-01

    Current industrial recovery of uranium from 30% phosphoric acid-produced by the dihydrate process-is based on solvent extraction method. Uranium recovery from concentrated phosphoric acid (45-52% P 2 O 5 ) produced by evaporation of the 30% acid or directly produced by the hemihydrate process, by solvent extraction is difficult to apply in practice. In addition to possible contamination of the acid by the organic solvents and/or their deterioration. This paper investigates the possibility of applying a precipitation method (Weterings and Janssen, 1985) for uranium recovery from both low (28% P 2 O 2 ) and high (48% P 2 O 5 ) concentration phosphoric acids produced by abu-Zaabal phosphoric acid plant (abu-Zaabal fertilizers and chemicals Co., Egypt). The 28% acid produced by H 2 SO 4 dihydrate method and the 48% acid produced by evaporation of the 28% acid

  14. Phosphorous gettering in acidic textured multicrystalline solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Montesdeoca-Santana, A. [Departamento de Fisica Basica, Universidad de La Laguna (ULL), Avenida Astrofisico Francisco Sanchez 2, 38206 La Laguna, S/C de Tenerife (Spain); Fraunhofer Institut fuer Solare Energiesysteme ISE, Laboratory and Servicecenter Gelsenkirchen, Auf der Reihe 2, 45884 Gelsenkirchen (Germany); Jimenez-Rodriguez, E.; Diaz-Herrera, B.; Hernandez-Rodriguez, C. [Departamento de Fisica Basica, Universidad de La Laguna (ULL), Avenida Astrofisico Francisco Sanchez 2, 38206 La Laguna, S/C de Tenerife (Spain); Gonzalez-Diaz, B. [Departamento de Fisica Basica, Universidad de La Laguna (ULL), Avenida Astrofisico Francisco Sanchez 2, 38206 La Laguna, S/C de Tenerife (Spain); Departamento de Energia Fotovoltaica, Instituto Tecnologico y de Energias Renovables. Poligono Industrial de Granadilla s/n, 38600 San Isidro-Granadilla de Abona, S/C de Tenerife (Spain); Rinio, M.; Borchert, D. [Fraunhofer Institut fuer Solare Energiesysteme ISE, Laboratory and Servicecenter Gelsenkirchen, Auf der Reihe 2, 45884 Gelsenkirchen (Germany); Guerrero-Lemus, R. [Departamento de Fisica Basica, Universidad de La Laguna (ULL), Avenida Astrofisico Francisco Sanchez 2, 38206 La Laguna, S/C de Tenerife (Spain); Fundacion de Estudios de Economia Aplicada, Catedra Focus-Abengoa, Jorge Juan 46, 28001 Madrid (Spain)

    2011-03-15

    The influence of phosphorus gettering is studied in this work applied to an acidic textured multicrystalline silicon substrate. The texturization was achieved with an HF/HNO{sub 3} solution leading to nanostructures on the silicon surface. It has been demonstrated in previous works that this textured surface decreases the reflectance on the solar cell and increases the surface area improving the photon collection and enhancing the short circuit current. The present study investigates the effect on the minority carrier lifetime of the phosphorous diffusion when it is carried out on this textured surface. The lifetime is measured by means microwave photoconductance decay and quasi steady state phototoconductance devices. The diffused textured wafers are used to fabricate solar cells and their electrical parameters are analyzed. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Organometallic catalysts for primary phosphoric acid fuel cells

    Science.gov (United States)

    Walsh, Fraser

    1987-01-01

    A continuing effort by the U.S. Department of Energy to improve the competitiveness of the phosphoric acid fuel cell by improving cell performance and/or reducing cell cost is discussed. Cathode improvement, both in performance and cost, available through the use of a class of organometallic cathode catalysts, the tetraazaannulenes (TAAs), was investigated. A new mixed catalyst was identified which provides improved cathode performance without the need for the use of a noble metal. This mixed catalyst was tested under load for 1000 hr. in full cell at 160 to 200 C in phosphoric acid H3PO4, and was shown to provide stable performance. The mixed catalyst contains an organometallic to catalyze electroreduction of oxygen to hydrogen peroxide and a metal to catalyze further electroreduction of the hydrogen peroxide to water. Cathodes containing an exemplar mixed catalyst (e.g., Co bisphenyl TAA/Mn) operate at approximately 650 mV vs DHE in 160 C, 85% H3PO4 with oxygen as reactant. In developing this mixed catalyst, a broad spectrum of TAAs were prepared, tested in half-cell and in a rotating ring-disk electrode system. TAAs found to facilitate the production of hydrogen peroxide in electroreduction were shown to be preferred TAAs for use in the mixed catalyst. Manganese (Mn) was identified as a preferred metal because it is capable of catalyzing hydrogen peroxide electroreduction, is lower in cost and is of less strategic importance than platinum, the cathode catalyst normally used in the fuel cell.

  16. Procedure for recovery from an uranium containing concentrate and phosphoric acid, as well as an uranium containing concentrate and phosphoric acid obtained by this procedure

    International Nuclear Information System (INIS)

    1980-01-01

    The phosphate ore is dissolved in sulphuric acid and the formed calcium sulphate is separated from the solution. The uranium is then precipitated by adding ammonium fluoride solution to the remaining phosphoric acid solution. When the phosphate ore is dissolved in sulphuric acid, fluorine gas is liberated and this is then used to produce the ammonium fluoride solution. (Th.P.)

  17. Phosphoric acid as a matrix additive for MALDI MS analysis of phosphopeptides and phosphoproteins

    DEFF Research Database (Denmark)

    Kjellström, Sven; Jensen, Ole Nørregaard

    2004-01-01

    ,5-dihydroxybenzoic acid (2,5-DHB) matrix. Phosphoric acid in combination with 2,5-DHB matrix significantly enhanced phosphopeptide ion signals in MALDI mass spectra of crude peptide mixtures derived from the phosphorylated proteins alpha-casein and beta-casein. The beneficial effects of adding up to 1% phosphoric...... acid to 2,5-DHB were also observed in LC-MALDI-MS analysis of tryptic phosphopeptides of B. subtilis PrkC phosphoprotein. Finally, the mass resolution of MALDI mass spectra of intact proteins was significantly improved by using phosphoric acid in 2,5-DHB matrix....

  18. Purification of wet process phosphoric acid by solvent extraction with long-chain aliphatic amines

    International Nuclear Information System (INIS)

    Stenstroem, S.

    1986-09-01

    Purification of phosphoric acid by solvent extraction with long-chain aliphatic amines is investigated. Extraction of cadmium is extensively examined regarding the importance of the aqueous phase, the diluent and the amine. The solubility of tri-n-octyl-amine is determined in water and phosphoric acid solutions. Properties of valuable constituent such as uranium and yttrium are screened. Modelling of the system is performed by adapting Bromley's model for electrolytes to the different dissociation/association equilibria in the aqueous phase. In the organic phase simple expressions are used for the non-ideal behaviour. Amine-acid equilibria are investigated for all acids present in industrial phosphoric acid. New extraction constants are calculated for phosphoric and hydro- fluosilic acid. Calculations are compared with experiments both from binary and multicomponent acid mixtures

  19. Spectrophotometric Analysis of Phosphoric Acid Leakage in High-Temperature Phosphoric Acid-Doped Polybenzimidazole Membrane Fuel Cell Application

    Directory of Open Access Journals (Sweden)

    Seungyoon Han

    2016-01-01

    Full Text Available High-temperature proton exchange membrane fuel cells (HT-PEMFCs utilize a phosphoric acid- (PA- doped polybenzimidazole (PBI membrane as a polymer electrolyte. The PA concentration in the membrane can affect fuel cell performance, as a significant amount of PA can leak from the membrane electrode assembly (MEA by dissolution in discharged water, which is a byproduct of cell operation. Spectrophotometric analysis of PA leakage in PA-doped polybenzimidazole membrane fuel cells is described here. This spectrophotometric analysis is based on measurement of absorption of an ion pair formed by phosphomolybdic anions and the cationoid color reagent. Different color reagents were tested based on PA detection sensitivity, stability of the formed color, and accuracy with respect to the amount of PA measured. This method allows for nondestructive analysis and monitoring of PA leakage during HT-PEMFCs operation.

  20. Determination of anions in pure and commercial phosphoric acid by ion chromatography and manual of 792 basic IC

    International Nuclear Information System (INIS)

    Al-Kabani, F.; Abdulbaki, M. K.

    2007-01-01

    A method for determination of anions in pure and concentrated phosphoric and samples (85%) and commercial phosphoric acid ion chromatography was developed, in order to control the specification of phosphoric acid produced in the pilot plant for phosphoric acid purification. The accuracy of the method was studied and the standard deviation was found to be between 0.09 and 0.10. Operation instructions of 792 Basic IC was described. (author)

  1. Phosphoric acid doped AB-PBI membranes and its applications in high temperature PEMFC

    DEFF Research Database (Denmark)

    He, Ronghuan; Qingfeng, Li; Bjerrum, Niels

    2005-01-01

    Poly(2,5-benzimidazole) (ab-PBI) was prepared from 3,4-diaminobenzoic acid via a polymerisation reaction. The obtained polymer exhibits excellent thermal stability in a temperature range ….. The membrane of ab-PBI when doped with phosphoric acid at room temperaturepresents high proton conductivit......C with phosphoric acid doped ab-PBI as the electrolyte under atmospheric pressure at 200°C without humidification....

  2. Liquid-Liquid Extraction of Uranium from Phosphoric acid by HDEHP- CYANEX 921 mixture

    International Nuclear Information System (INIS)

    El-Reefy, S.A.; Awwad, N.S.; Aly, H.F.

    1998-01-01

    The extraction of uranyl ions from different phosphoric acid media by CYANEX-921 (a commercial trioctyl trioctyl phosphine oxide) mixed with di-2-ethylhexyl phosphoric acid diluted with odorless kerosene was studied. The factors affecting the extraction at equilibrium such as, phosphoric acid concentration, CYANEX-921 concentration, HDEHP concentration, and temperature were investigated. It was found that, the extraction of uranium by the organic phase increasing. CYANEX or HDEHP concentrations. It was also found that the distribution ratio slightly increases by increasing the extraction temperature from 15 to 25 degree C, this is followed by gradual decrease in the extraction at higher temperature

  3. Complexity in Acid-Base Titrations: Multimer Formation Between Phosphoric Acids and Imines.

    Science.gov (United States)

    Malm, Christian; Kim, Heejae; Wagner, Manfred; Hunger, Johannes

    2017-08-10

    Solutions of Brønsted acids with bases in aprotic solvents are not only common model systems to study the fundamentals of proton transfer pathways but are also highly relevant to Brønsted acid catalysis. Despite their importance the light nature of the proton makes characterization of acid-base aggregates challenging. Here, we track such acid-base interactions over a broad range of relative compositions between diphenyl phosphoric acid and the base quinaldine in dichloromethane, by using a combination of dielectric relaxation and NMR spectroscopy. In contrast to what one would expect for an acid-base titration, we find strong deviations from quantitative proton transfer from the acid to the base. Even for an excess of the base, multimers consisting of one base and at least two acid molecules are formed, in addition to the occurrence of proton transfer from the acid to the base and simultaneous formation of ion pairs. For equimolar mixtures such multimers constitute about one third of all intermolecular aggregates. Quantitative analysis of our results shows that the acid-base association constant is only around six times larger than that for the acid binding to an acid-base dimer, that is, to an already protonated base. Our findings have implications for the interpretation of previous studies of reactive intermediates in organocatalysis and provide a rationale for previously observed nonlinear effects in phosphoric acid catalysis. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  4. Molten Carbonate and Phosphoric Acid Stationary Fuel Cells: Overview and Gap Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Remick, R.; Wheeler, D.

    2010-09-01

    This report describes the technical and cost gap analysis performed to identify pathways for reducing the costs of molten carbonate fuel cell (MCFC) and phosphoric acid fuel cell (PAFC) stationary fuel cell power plants.

  5. [3,3]Paracyclophanes as planar chiral scaffolds for the synthesis of new phosphoric acids.

    Science.gov (United States)

    Stemper, Jérémy; Isaac, Kevin; Duret, Véronique; Retailleau, Pascal; Voituriez, Arnaud; Betzer, Jean-François; Marinetti, Angela

    2013-07-11

    Cyclic phosphoric acids displaying planar chiral paracyclophane structures, which include a 1,1'-ferrocenediyl unit, have been designed as a new class of chiral organocatalysts. Their synthesis, optical resolution, structural characterization and preliminary catalytic tests are reported.

  6. A new planetary structure fabrication process using phosphoric acid

    Science.gov (United States)

    Buchner, Christoph; Pawelke, Roland H.; Schlauf, Thomas; Reissner, Alexander; Makaya, Advenit

    2018-02-01

    Minimising the launch mass is an important aspect of exploration mission planning. In-situ resource utilisation (ISRU) can improve this by reducing the amount of terrestrial materials needed for planetary exploration activities. We report on a recently concluded investigation into the requirements and available technologies for creating hardware on extra-terrestrial bodies, using the limited resources available on site. A trade-off of ISRU technologies for hardware manufacturing was conducted. A new additive manufacturing process suitable for fabricating structures on the Moon or Mars was developed. The process uses planetary regolith as the base material and concentrated phosphoric acid as the liquid binder. Mixing the reagents creates a sticky construction paste that slowly solidifies into a hard, rock-like material. Prior to solidification, the paste is extruded in layers, creating the desired structures in a 3D printing process. We used Martian regolith simulant JSC-Mars-1A, but the process is not selective towards regolith composition. Samples were exposed to thermal cycles and were mechanically characterised. Reduced-scale demonstrator structures were printed to demonstrate structure fabrication using the developed process.

  7. Determination of formal potential of Amsup((4))/Amsup((3)) pair in phosphoric-acid solutions

    International Nuclear Information System (INIS)

    Mikhajlov, V.M.; Myasoedov, B.F.

    1977-01-01

    Values of formal potentials of the system Amsup((4))/Amsup((3)) in 12 and 15 M phosphoric acid at 20+-2 deg C are determined by potentiometric method. The effect is studied of metallic platinum on the process of self-reduction of tetravalent americium, and the optimum conditions are found for potentiostatic oxidation of Amsup((3)) to Amsup((4)) in 12 M phosphoric acid

  8. Oxidation-extraction of uranium from wet-process phosphoric acid

    International Nuclear Information System (INIS)

    Lawes, B.C.

    1985-01-01

    The invention involves an improvement to the reductive stripping process for recovering uranium values from wet-process phosphoric acid solution, where uranium in the solution is oxidized to uranium (VI) oxidation state and then extracted from the solution by contact with a water immiscible organic solvent, by adding sufficient oxidant, hydrogen peroxide, to obtain greater than 90 percent conversion of the uranium to the uranium (VI) oxidation state to the phosphoric acid solution and simultaneously extracting the uranium (VI)

  9. The use of ion chromatography for the determination of impurities in crude phosphoric acid

    International Nuclear Information System (INIS)

    Pires, M.A.F.; Atalla, L.T.; Abrao, A.

    1988-07-01

    The determination of fluoride, nitrate, sulphate and phosphate ions in crude phosphoric acid by means of ion chromatography is described. A previous separation of interferent cations was made by using a cationic resin or EDTA complexation. The last alternative allowed more reproductible results. The technique described is very quick and is being applied for the simultaneous determination of impurities in phosphoric acid and its own phosphospate concentration. The method is quick and has good reprodutibility. (author) [pt

  10. Recent studies of uranium recovery from wet-process phosphoric acid with octylphenyl acid phosphate

    International Nuclear Information System (INIS)

    Arnold, W.D.

    1978-01-01

    Commercial OPAP is a complex mixture that contains at least 11 components. Octyl phenol is the principal impurity. Commercial OPAP contains readily-hydrolyzable material. The concentrations of octyl phenol and an unidentified impurity increase in the hydrolyzed product. Uranium extraction power is decreased slightly by hydrolysis of the reagent. Four major problems were encountered in continuous stability tests: (1) Microemulsion or micelle formation--loss of organic phase into phosphoric acid. We do not have a solution to this problem at this time. It could involve alteration of the organic, e.g., adding a modifier, changing the reagent structure, or changing the diluent. (2) Reagent poisoning--reduction of uranium extraction and interference with organic titrations by material extracted from the acid. Additional work is needed to identify the poisoning material or materials. It can then be removed if it originates in the phosphate rock, or avoided if it originates in chemicals added during processing. (3) Crystallization with iron--loss of both major components of the reagent as a complex with ferric iron. We believe this problem can be controlled by controlling the ferric iron concentration in the phosphoric acid. (4) MOPPA distribution loss--a selective loss to the aqueous phase. We believe this can be minimized by controlling the iron concentration of the phosphoric acid. The iron concentration will need to be kept low enough to avoid reagent crystallization and high enough to avoid MOPPA distribution loss. 15 figs

  11. Recovery of uranium in the production of concentrated phosphoric acid by a hemihydrate process

    International Nuclear Information System (INIS)

    Nakajima, S.; Miyamoto, M.

    1983-01-01

    Nissan Chemical Industries as manufacturers of phosphoric acid have studied the recovery of uranium, based on a concentrated phosphoric acid production process. The process consists of two stages, a hemihydrate stage with a formation of hemihydrate and a filtration section, followed by a dihydrate stage with hydration and a filtration section. In the hemihydrate stage, phosphate is treated with a mixture of phosphoric acid and sulphuric acid to produce phosphoric acid and hydrous calcium sulphate; the product is recovered in the filtration section and its concentration is 40-50% P 2 O 3 . In the dihydrate stage, the hemihydrate is transformed by re-dissolution and hydration, producing hydrous calcium sulphate, i.e. gypsum. This process therefore comprises two parts, each with different acid concentrations. As the extraction of uranium is easier in the case of a low concentration of phosphoric acid, the process consists of the recovery of uranium starting from the filtrate of the hydration section. The tests have shown that the yield of recovery of uranium was of the order of 80% disregarding the handling losses and no disadvantageous effect has been found in the combination of the process of uranium extraction with the process of concentrated phosphoric acid production. Compared with the classical process where uranium is recovered from acid with 30% P 2 O 5 , the process of producing high-concentration phosphoric acid such as the Nissan process, in which the uranium recovery is effected from acid with 15% P 2 O 5 from the hydration section, presents many advantages [fr

  12. Application of a precipitation method for uranium recovery from abu-zaabal phosphoric acid plant, Egypt

    International Nuclear Information System (INIS)

    El-hazek, N.M.T.; Hussein, E.M.

    1995-01-01

    Current industrial recovery of uranium from 30% phosphoric acid-produced by the dihydrate process-is based on solvent extraction method. Uranium recovery from concentrated phosphoric acid (45-52% p o5 ) produced by evaporation of the 30% acid or directly produced by the hemihydrate process, by solvent extraction is difficult to apply in practice. In addition to possible contamination of the acid by the organic solvents and/or their deterioration. This paper investigates the possibility of applying a precipitation method (Weterings and Janssen, 1985) for uranium recovery from both low (28% P 2 O 5 ) and high (48% P 2 O 5 ) concentration phosphoric acids produced by abu-zaabal phosphoric acid plant (Abuzaabal fertilizers and chemicals Co., Egypt). The 28% acid produced by H 2 SO 4 dihydrate method and the 48% acid produced by evaporation of the 28% acid The applied precipitation method depends on using NH 4 F as a uranium precipitant from both low and high concentration phosphoric acids in presence of acetone as a dispersing agent. All the relevant factors have been studied

  13. Doping phosphoric acid in polybenzimidazole membranes for high temperature proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    He, Ronghuan; Li, Qingfeng; Jensen, Jens Oluf

    2007-01-01

    Polybenzimidazole (PBI) membranes were doped in phosphoric acid solutions of different concentrations at room temperature. The doping chemistry was studied using the Scatchard method. The energy distribution of the acid complexation in polymer membranes is heterogeneous, that is, there are two...... different types of sites in PBI for the acid doping. The protonation constants of PBI by phosphoric acid are found to be 12.7 L mol(-1) (K-1) for acid complexing sites with higher affinity, and 0.19 L mol(-1) (K-2) for the sites with lower affinity. The dissociation constants for the complexing acid onto...... these two types of PBI sites are found to be 5.4 X 10(-4) and 3.6 X 10(-2), respectively, that is, about 10 times smaller than that of aqueous phosphoric acid in the first case but 5 times higher in the second. The proton conducting mechanism is also discussed....

  14. External radiation assessment in a wet phosphoric acid production plant

    Energy Technology Data Exchange (ETDEWEB)

    Bolivar, J.P.; Perez-Moreno, J.P. [Dept. Fisica Aplicada, Facultad de Ciencias Experimentales, Universidad de Huelva, 21012 Huelva (Spain); Mas, J.L. [Dept. Fisica Aplicada I, Escuela Universitaria Politecnica, Universidad de Sevilla, 41012 Sevilla (Spain)], E-mail: ppmasb@us.es; Martin, J.E.; San Miguel, E.G. [Dept. Fisica Aplicada, Facultad de Ciencias Experimentales, Universidad de Huelva, 21012 Huelva (Spain); Garcia-Tenorio, R. [Dept. Fisica Aplicada II, Escuela Tecnica Superior de Arquitectura, Universidad de Sevilla, 41012 Sevilla (Spain)

    2009-10-15

    The factories dedicated to the production of phosphoric acid by the so-called wet acid method are usually considered typical NORM industries, because the phosphate rock used as raw material usually contains high concentrations of {sup 238}U-series radionuclides. The magnitude and behaviour of the radionuclides involved in the production process revealed the need to determine its dosimetric impact on workers. This work aims to partially compensate this lack of knowledge through the determination of external effective dose rates at different zones in the process at a typical plant located in the southwest of Spain. To this end, two dosimetric sampling campaigns have been carried out at this phosphoric acid production plant. The first sampling was carried out when phosphate rocks originating in Morocco were processed, and the second one when phosphate rock processed came from the Kola Peninsula (Russia Federation). This differentiation was necessary because the activity concentrations are almost one order of magnitude higher in Moroccan phosphate rock than in Kola phosphate rock. The results obtained have reflected external dose rate enhancements as high as 1.4 {mu}Sv h{sup -1} (i.e., up to thirty times the external exposition due to radionuclides in unperturbed soils) at several points in the facility, particularly where the digested rock (pulp) is filtered. However, the most problematic points are characterised by a small occupation factor. That means that the increment in the annual effective external gamma dose received by the most-exposed worker is clearly below 1 mSv (European Commission limit for the general population) under normal production. Nevertheless, special care in the design and schedule of cleaning and maintaining work in the areas with high doses should be taken in order to avoid any possibility of exceeding the previously mentioned general population limit. In addition, the results of the dosimetric campaign showed no clear correlation between {sup

  15. Physicochemical properties of phosphoric acid doped polybenzimidazole membranes for fuel cells

    DEFF Research Database (Denmark)

    He, Ronghuan; Li, Qingfeng; Bach, Anders

    2006-01-01

    Polybenzimidazole (PBI) membranes have been prepared with different molecular weights. The water and acid swelling, mechanical strength,gas permeability and proton conductivity were studied for the pristine and acid doped PBI membranes. When doped with 5 mol of phosphoric acid per mole repeat unit...

  16. Limiting Current of Oxygen Reduction on Gas-Diffusion Electrodes for Phosphoric Acid Fuel Cells

    DEFF Research Database (Denmark)

    Li, Qingfeng; Gang, Xiao; Hjuler, Hans Aage

    1994-01-01

    on polytetrafluorine-ethyl bonded gas-diffusion electordes in phosphoric acid with and without fluorinated additives. This provides an alternative to estimate the film thickness by combining it with the acid-adsorption measurements and the porosity analysis of the catalyst layer. It was noticed that the limiting...... expression for the limiting current density. The acid-film thickness estimated this way was found to be of 0.1 mum order of magnitude for the two types of electrodes used in phosphoric acid with and without fluorinated additives at 150-degrees-C....

  17. Studies on extraction of beryllium by di-(2-ethylhexyl)-phosphoric acid from hydrochloric acid solutions

    International Nuclear Information System (INIS)

    El-Yamani, I.S.; Farah, M.Y.; Adb El-Messieh, E.N.

    1978-01-01

    The distribution of Be between aqueous HCl solutions and organic phases of di-(2-ethyl hexyl)-phosphoric acid has been described. Equal volumes of both the tracer-labelled aqueous phase and the organic phase were mixed together in separatory funnels then shaken mechanically at room temperature. After centrifugation, aliquots of both phases were counted in the γ-scintillation counter. In all experiments, duplicates were made and average values recorded. The dependence of extraction on aqueous acidity, metal and extractant concentration as also on the diluent type, was thoroughly examined. The possible mechanism of extraction has been discussed in the light of results obtained. (T.G.)

  18. Comparison of different phosphorous adsorption models in acid ...

    African Journals Online (AJOL)

    This study was designed to compare the phosphorous fixation capacity of three soils series named Tyele, Minkonmingon and Mekoto in the south region of Cameroon and to determine the soil properties that are the main predictors of the P activity of those soils. Five adsorption equations viz. Linear, Langmuir, Van Huay, ...

  19. Glass microporous fiber/nanoporous polytetrafluoroethene composite membranes for high efficient phosphoric acid fuel cell

    International Nuclear Information System (INIS)

    Lu, Chia-Lien; Lee, Wei-Jia; Tseng, Fan-Gang; Chang, Cheng-Ping

    2014-01-01

    This paper reports a high efficient phosphoric acid fuel cell by employing a micro/nano composite proton exchange membrane incorporating glass microfiber (GMF) sealed by polytetrafluoroethylene (PTFE) nano-porous film. This multilayer membrane not only possesses both thermal and chemical stability at phosphoric acid fuel cell working temperature at 150∼220°C but also is cost effective. As a result, the inclusion of the high porosity and proton conductivity from glass microfiber and the prevention of phosphoric acid leakage from PTEF nano film can be achieved at the same time.The composite membrane maximum proton conductivity achieves 0.71 S/cm at 150 °C from AC impedance analysis, much higher than common phosphoric acid porous membranes For single cell test, The GMF fuel cell provides a 63.6mW/cm2 power density at 200mA/cm2 current density while GMF plus methanol treated PTFE (GMF+mPTFE) provides 59.2mW/cm2 power density at 160mA/cm2 current density for hydrogen and oxygen supply at 150 °C. When we change the electrodes that are more suited for phosphoric acid fuel cell, the GMF+mPTFE single cell gets higher performance which achieve 296mW/cm2 power density at 900mA/cm2 current density for hydrogen and oxygen supply at 150 °C

  20. Preparation and cytocompatibility evaluation for hydrosoluble phosphorous acid-derivatized cellulose as tissue engineering scaffold material.

    Science.gov (United States)

    Petreus, Tudor; Stoica, Bogdan Alexandru; Petreus, Oana; Goriuc, Ancuta; Cotrutz, Carmen-Elena; Antoniac, Iulian-Vasile; Barbu-Tudoran, Lucian

    2014-04-01

    Chemical modification of cellulose by phosphorylation enhances its bioactivity and provides new derivatives and materials with specific end uses. In the present study, cellulose derivatized with phosphorous acid was obtained using the reaction of microcrystalline cellulose with phosphorous acid-urea mixture, in molten state, in comparison with others methods that used different solvents and catalysts. Completely water soluble films with a substitution degree close to one were obtained and characterized by analytical and spectral analysis (FT-IR, (31)P NMR), contact angle, metallographic microscopy and atomic force microscopy (AFM). 31P NMR spectra of derivatized cellulose showed a signal at 2.58 ppm (assigned to P-O-C6) while the doublets at 4.99-5.29 and at 7.38 ppm were assigned to P-O-C2 and P-O-C3, respectively; thus, the formation of monosubstituted phosphorous acid esters of cellulose is advocated. Contact angle measurements showed that the work of adhesion is more important in water than in ethylene glycol, for the phosphorous acid derivatized cellulose. The cytocompatibility of this hydrosoluble derivatized cellulose was tested by direct contact and also by indirect assays on normal human dermal fibroblasts and on osteoblast-like cells (human osteosarcoma). Cell growth on phosphorylated cellulose pellicle and the results from viability assays had shown a good cytocompatibility and lack of toxicity. Phosphorous acid derivatized cellulose would offer a promising biomaterial, useful as scaffolds for new biopolymer composites, and subject for further development as an ionic crosslinker.

  1. Phosphoric acid purification through different raw and activated clay materials (Southern Tunisia)

    Science.gov (United States)

    Trabelsi, Wafa; Tlili, Ali

    2017-05-01

    This study concerns the purification of Tunisian phosphoric acid produced by the Tunisian Chemical Group (TCG), using raw and activated clays materials from Southern Tunisia. The Gafsa basin clays samples (Jebel Hamadi (JHM); Jebel Stah (JS) and the El Hamma sample (Jebel Aïdoudi (JAD)) were activated with 3 M, HCl solution. Phosphoric acid purification was performed on raw and activated clays. Mineralogical characterisation was carried out using the X-ray powder diffraction method and infrared absorption spectroscopy. Textural changes between raw and activated clays were identified using SEM observations and specific surface analysis. Jebel Hamadi clays were almost dominated by smectite associated with kaolinite and illite traces, while Jebel Stah and Jebel Aïdoudi clays were composed of the association of smectite, illite and kaolinite. It is worth noting that the position of the smectite (001) reflection increased after the acidic activation in all studied samples, indicating the relaxation of the smectite structure along the c-axis. This was corroborated by the increasing specific surface area of the clay particles with the activation process. The specific surface area was close to 50 m2/g and 200 m2/g, for raw and activated materials, respectively. The maximum phosphoric acid purification was obtained by using activated clays with 3 N HCl for 4 h. This performance correlated with the maximum of the external specific surface area which generated strong acid sites. Furthermore, the best results of phosphoric acids purification from TCG were obtained at a specific consumption equivalent to 30 Kg of clay/ton of P2O5. These results showed that the best phosphoric acid purification was yielded by Jebel Aïdoudi clay. In all cases, the highest organic carbon reduction rates in the phosphoric acid after filtration were obtained at 90°C.

  2. Planar chiral phosphoric acids with biphenylene-tethered paracyclophane scaffolds: synthesis, characterization, and catalytic screening.

    Science.gov (United States)

    Isaac, Kévin; Stemper, Jérémy; Servajean, Vincent; Retailleau, Pascal; Pastor, Julien; Frison, Gilles; Kaupmees, Karl; Leito, Ivo; Betzer, Jean-François; Marinetti, Angela

    2014-10-17

    Phosphoric acids with planar chiral paracyclophane scaffolds have been prepared in optically pure form starting from 1,8-dibromobiphenylene, by means of a chiral phosphorodiamidate as the phosphorylating agent. Structural characterization and configurational assignment have been performed by X-ray diffraction studies. The acids promote the organocatalytic enantioselective H-transfer reduction of α-arylquinolines with up to 90% enantiomeric excess.

  3. Dissociation constants of phosphoric acid in dimethylformamide-water mixtures at 298.15 K

    Science.gov (United States)

    Safonova, L. P.; Fadeeva, Yu. A.; Pryakhin, A. A.

    2009-10-01

    The dissociation constants of phosphoric acid (p K 1 and p K 2) in water-dimethylformamide (DMFA) mixtures (0-0.65 mole fractions of DMFA) were determined at 298.15 K by potentiometric titration. The extrapolation of these data to pure DMFA and the comparative calculation method were used to estimate the dissociation constants of the acid in DMFA.

  4. Rare earth elements recycling from waste phosphor by dual hydrochloric acid dissolution.

    Science.gov (United States)

    Liu, Hu; Zhang, Shengen; Pan, Dean; Tian, Jianjun; Yang, Min; Wu, Maolin; Volinsky, Alex A

    2014-05-15

    This paper is a comparative study of recycling rare earth elements from waste phosphor, which focuses on the leaching rate and the technical principle. The traditional and dual dissolution by hydrochloric acid (DHA) methods were compared. The method of dual dissolution by hydrochloric acid has been developed. The Red rare earth phosphor (Y0.95Eu0.05)2O3 in waste phosphor is dissolved during the first step of acid leaching, while the Green phosphor (Ce0.67Tb0.33MgAl11O19) and the Blue phosphor (Ba0.9Eu0.1MgAl10O17) mixed with caustic soda are obtained by alkali sintering. The excess caustic soda and NaAlO2 are removed by washing. The insoluble matter is leached by the hydrochloric acid, followed by solvent extraction and precipitation (the DHA method). In comparison, the total leaching rate of the rare earth elements was 94.6% by DHA, which is much higher than 42.08% achieved by the traditional method. The leaching rate of Y, Eu, Ce and Tb reached 94.6%, 99.05%, 71.45%, and 76.22%, respectively. DHA can decrease the consumption of chemicals and energy. The suggested DHA method is feasible for industrial applications. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Uranium recovery from the concentrated phosphoric acid prepared by the hemi-hydrate process

    International Nuclear Information System (INIS)

    Fouad, E.A.; Mahdy, M.A.; Bakr, M.Y.; Zatout, A.A.

    1995-01-01

    It has been proved that the uranium dissolution from El-sebaiya phosphate ore was possible by using 10 Kg of K Cl O 4 / ton rock during the preparation of high strength phosphoric acid using the hemi hydrate process. In the present work, effective extraction of uranium (about 90%) from the high strength phosphoric acid using a new synergistic solvent mixture of 0.75 M D 2 EHPA/0.1 M TOHPO had been a success. Stripping of uranium from the organic phase was possible by 10 M phosphoric acid while the direct precipitation of uranium concentrate from the later was feasible by using N H 4 F in presence of acetone. 8 figs

  6. Self-Supported BINOL-Derived Phosphoric Acid Based on a Chiral Carbazolic Porous Framework.

    Science.gov (United States)

    Zhang, Xiang; Kormos, Attila; Zhang, Jian

    2017-11-17

    The facile synthesis of a porous heterogeneous BINOL-derived chiral phosphoric acid BiCz-POF-1 using the mild, FeCl 3 -promoted oxidative polymerization is reported. For the first time, carbazole is introduced at the 3,3'-positions of the chiral BINOL-derived phosphoric acid to (1) offer steric hindrance for achieving a high enantioselectivity and (2) serve as a cross-linker for the construction of the porous solid catalyst. BiCz-POF-1 exhibits remarkable catalytic activity and enantioselectivity toward transfer hydrogenation of 1,4-benzoxazine, 1,4-benzoxazinone, and 2-phenylquinolone. Combined with its facile synthesis and excellent recyclability, BiCz-POF-1 represents a new class of heterogeneous chiral phosphoric acid that has wide potential utility in enantioselective organocatalysis.

  7. Morphology of the dentin on primary molars after the application of phosphoric acid under different conditions

    Directory of Open Access Journals (Sweden)

    Renata Antonini Pimenta

    2010-09-01

    Full Text Available The aim of this study was to evaluate changes in the superficial dentin pattern of primary teeth after applying different phosphoric acid concentrations and conditioning times. Twenty-four dentin surfaces were divided in 4 groups with 10 teeth each: GI -no treatment; GII to GIV -phosphoric acid at 37%, 32%, and 10% respectively. The samples were divided into two halves: one treated for 7 seconds (T1 and the other one for 15 seconds (T2. They were submitted to scanning electronic microscopy (SEM. A reticule was superimposed upon the images to randomly select dentinal tubules measured in µm². The conditioning times did not cause significant differences in the mean diameter values of the dentin tubules within each test group: GII (T1= 4.86; T2= 4.70; GIII (T1 = 3.83; T2= 3.08; GIV (T1= 5.04; T2= 5.23. Comparing different groups, there were no differences in T1. The same results were observed in T2, except for GIV which presented higher mean diameter values than GIII. The extent of acid conditioning did not influence tubule opening within groups. When different types of acids where compared, only the 10% phosphoric acid showed upper tubule opening than 32% phosphoric acid. The dentin pattern varied according to the type of acid used for conditioning.

  8. Process engineering challenges of uranium extraction from phosphoric acid on industrial scale

    International Nuclear Information System (INIS)

    Mouriya, Govind; Singh, Dhirendra; Nath, A.K.; Majumdar, D.

    2014-01-01

    Heavy Water Board (HWB) is a constituent unit of the Department of Atomic Energy. One of the diversified activities undertaken by HWB is pursuing exploitation of non-conventional resources for recovery of uranium from wet phosphoric acid being the most prominent one. Amongst the feasible processes for recovery of uranium from phosphoric acid is solvent extraction. Use of in-house solvent produced by HWB, is another key driver. To garner necessary information for developing the industrial scale facilities, the process has been studied in the laboratory scale, mini scale, bench scale at Heavy Water Plant, Talcher. The process was subsequently scaled up to an industrial prototype scale unit and was set up as a Technology Demonstration Plant coupled with a commercial phosphoric acid plant. The plant has successfully processed more than 2 lakh m 3 of wet phosphoric acid and all the parameters including the product, Yellow Cake have been qualified. No adverse effect has been observed in the fertilizer produced. The main characteristics of the process and subsequent process innovations are discussed in this paper. These innovations have been carried out to overcome hurdles faced during commissioning and subsequent operations of the Plant. The innovations include improved pretreatment of the wet phosphoric acid for feeding to the extraction cycle, improved control of the first cycle chemical environment, reducing the strength of the phosphoric acid used for stripping, reducing the number of equipment and machineries, alteration in solvent composition used in the first and second cycle in the solvent extraction units of the plant. (author)

  9. Porous structure and surface chemistry of phosphoric acid activated carbon from corncob

    International Nuclear Information System (INIS)

    Sych, N.V.; Trofymenko, S.I.; Poddubnaya, O.I.; Tsyba, M.M.; Sapsay, V.I.; Klymchuk, D.O.; Puziy, A.M.

    2012-01-01

    Highlights: ► Phosphoric acid activation results in formation of carbons with acidic surface groups. ► Maximum amount of surface groups is introduced at impregnation ratio 1.25. ► Phosphoric acid activated carbons show high capacity to copper. ► Phosphoric acid activated carbons are predominantly microporous. ► Maximum surface area and pore volume achieved at impregnation ratio 1.0. - Abstract: Active carbons have been prepared from corncob using chemical activation with phosphoric acid at 400 °C using varied ratio of impregnation (RI). Porous structure of carbons was characterized by nitrogen adsorption and scanning electron microscopy. Surface chemistry was studied by IR and potentiometric titration method. It has been shown that porosity development was peaked at RI = 1.0 (S BET = 2081 m 2 /g, V tot = 1.1 cm 3 /g), while maximum amount of acid surface groups was observed at RI = 1.25. Acid surface groups of phosphoric acid activated carbons from corncob includes phosphate and strongly acidic carboxylic (pK = 2.0–2.6), weakly acidic carboxylic (pK = 4.7–5.0), enol/lactone (pK = 6.7–7.4; 8.8–9.4) and phenol (pK = 10.1–10.7). Corncob derived carbons showed high adsorption capacity to copper, especially at low pH. Maximum adsorption of methylene blue and iodine was observed for carbon with most developed porosity (RI = 1.0).

  10. Porous structure and surface chemistry of phosphoric acid activated carbon from corncob

    Energy Technology Data Exchange (ETDEWEB)

    Sych, N.V.; Trofymenko, S.I.; Poddubnaya, O.I.; Tsyba, M.M. [Institute for Sorption and Endoecology Problems, National Academy of Sciences of Ukraine, 13 General Naumov St., 03164 Kyiv (Ukraine); Sapsay, V.I.; Klymchuk, D.O. [M.G. Kholodny Institute of Botany, National Academy of Sciences of Ukraine, 2 Tereshchenkivska St., 01601 Kyiv (Ukraine); Puziy, A.M., E-mail: alexander.puziy@ispe.kiev.ua [Institute for Sorption and Endoecology Problems, National Academy of Sciences of Ukraine, 13 General Naumov St., 03164 Kyiv (Ukraine)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Phosphoric acid activation results in formation of carbons with acidic surface groups. Black-Right-Pointing-Pointer Maximum amount of surface groups is introduced at impregnation ratio 1.25. Black-Right-Pointing-Pointer Phosphoric acid activated carbons show high capacity to copper. Black-Right-Pointing-Pointer Phosphoric acid activated carbons are predominantly microporous. Black-Right-Pointing-Pointer Maximum surface area and pore volume achieved at impregnation ratio 1.0. - Abstract: Active carbons have been prepared from corncob using chemical activation with phosphoric acid at 400 Degree-Sign C using varied ratio of impregnation (RI). Porous structure of carbons was characterized by nitrogen adsorption and scanning electron microscopy. Surface chemistry was studied by IR and potentiometric titration method. It has been shown that porosity development was peaked at RI = 1.0 (S{sub BET} = 2081 m{sup 2}/g, V{sub tot} = 1.1 cm{sup 3}/g), while maximum amount of acid surface groups was observed at RI = 1.25. Acid surface groups of phosphoric acid activated carbons from corncob includes phosphate and strongly acidic carboxylic (pK = 2.0-2.6), weakly acidic carboxylic (pK = 4.7-5.0), enol/lactone (pK = 6.7-7.4; 8.8-9.4) and phenol (pK = 10.1-10.7). Corncob derived carbons showed high adsorption capacity to copper, especially at low pH. Maximum adsorption of methylene blue and iodine was observed for carbon with most developed porosity (RI = 1.0).

  11. Brewer’s Spent Grain Valorization Using Phosphoric Acid Pretreatment for Second Generation Bioethanol Production

    DEFF Research Database (Denmark)

    Romero, I.; Ruiz, E.; Cara, C.

    Brewer’s spent grain constitutes a byproduct of beer making process yearly generated in big amounts and lacking of economic feasible applications. This lignocellulosic residue was characterized and pretreated by dilute phosphoric acid according to a rotatable central composite design to evaluate...... the effect of phosphoric acid concentration (2-6% w/v) and pretreatment temperature (140-180ºC). The influence of these factors on the hemicellulosic sugar solubilisation and the subsequent enzymatic hydrolysis was evaluated. Optimal pretreatment conditions were determined by maximizing both...... hemicellulosic sugar recovery in liquids and enzymatic hydrolysis yield....

  12. Why do proton conducting polybenzimidazole phosphoric acid membranes perform well in high-temperature PEM fuel cells?

    Science.gov (United States)

    Melchior, Jan-Patrick; Majer, Günter; Kreuer, Klaus-Dieter

    2016-12-21

    Transport properties and hydration behavior of phosphoric acid/(benz)imidazole mixtures are investigated by diverse NMR techniques, thermogravimetric analysis (TGA) and conductivity measurements. The monomeric systems can serve as models for phosphoric acid/poly-benzimidazole membranes which are known for their exceptional performance in high temperature PEM fuel cells. 1 H- and 31 P-NMR data show benzimidazole acting as a strong Brønsted base with respect to neat phosphoric acid. Since benzimidazole's nitrogens are fully protonated with a low rate for proton exchange with phosphate species, proton diffusion and conduction processes must take place within the hydrogen bond network of phosphoric acid only. The proton exchange dynamics between phosphate and benzimidazole species pass through the intermediate exchange regime (with respect to NMR line separations) with exchange times being close to typical diffusion times chosen in PFG-NMR diffusion measurements (ms regime). The resulting effects, as described by the Kärger equation, are included into the evaluation of PFG-NMR data for obtaining precise proton diffusion coefficients. The highly reduced proton diffusion coefficient within the phosphoric acid part of the model systems compared to neat phosphoric acid is suggested to be the immediate consequence of proton subtraction from phosphoric acid. This reduces hydrogen bond network frustration (imbalance of the number of proton donors and acceptors) and therefore also the rate of structural proton diffusion, phosphoric acid's acidity and hygroscopicity. Reduced water uptake, shown by TGA, goes along with reduced electroosmotic water drag which is suggested to be the reason for PBI-phosphoric acid membranes performing better in fuel cells than other phosphoric-acid-containing electrolytes with higher protonic conductivity.

  13. Phosphoric acid doped polysulfone membranes with aminopyridine pendant groups and imidazole cross-links

    DEFF Research Database (Denmark)

    Hink, Steffen; Elsøe, Katrine; Cleemann, Lars Nilausen

    2015-01-01

    Udel polysulfone based membranes with 4-aminopyridine pendant groups and cross-linking imidazole units are synthesized in a simple two step reaction. The ratio of 4-aminopyridine and imidazole is varied and the materials are extensively characterized. The average phosphoric acid uptake (in 85 wt%...

  14. Phosphoric acid doped imidazolium polysulfone membranes for high temperature proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    Yang, Jingshuai; Li, Qingfeng; Jensen, Jens Oluf

    2012-01-01

    A novel acid–base polymer membrane is prepared by doping of imidazolium polysulfone with phosphoric acid for high temperature proton exchange membrane fuel cells. Polysulfone is first chloromethylated, followed by functionalization of the chloromethylated polysulfone with alkyl imidazoles i.e. me...

  15. Determination of elemental impurities in phosphoric acid by INAA employing a novel method of phosphate precipitation

    Czech Academy of Sciences Publication Activity Database

    Kameník, Jan; Amsil, H.; Kučera, Jan

    2015-01-01

    Roč. 304, APR (2015), s. 157-162 ISSN 0236-5731 R&D Projects: GA ČR(CZ) GBP108/12/G108; GA MŠk LM2011019 Institutional support: RVO:61389005 Keywords : instrumental neutron activation analysis * phosphoric acid * elemental impurities * isothermal distillation Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 0.983, year: 2015

  16. Determination of elemental impurities in phosphoric acid by INAA employing a novel method of phosphate precipitation

    Czech Academy of Sciences Publication Activity Database

    Kameník, Jan; Amsil, H.; Kučera, Jan

    2014-01-01

    Roč. 2014, AUG (2014), s. 3455 ISSN 1588-2780 R&D Projects: GA ČR(CZ) GBP108/12/G108; GA MŠk(XE) LM2011019 Institutional support: RVO:61389005 Keywords : instrumental neutron activation analysis * phosphoric acid * elemental impurities * isothermal distillation Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders

  17. Influence of pH-control in phosphoric acid treatment of zinc oxide

    Energy Technology Data Exchange (ETDEWEB)

    Onoda, H., E-mail: onoda@kpu.ac.jp [Department of Informatics and Environmental Sciences, Kyoto Prefectural University (Japan); Chemel, M. [Ecole de Biologie Industrielle, CERGY Cedex (France)

    2017-04-15

    Zinc oxide is often used as a white pigment for cosmetics; however, it shows photocatalytic activity that causes decomposition of sebum on the skin when exposed to the ultraviolet radiation in sunlight. In this work, zinc oxide was reacted with phosphoric acid at various pH values to synthesize a novel white pigment for cosmetics. The chemical composition, powder properties, photocatalytic activities, colors, and smoothness of these pigments were studied. The obtained materials exhibited X-ray diffraction peaks relating to zinc oxide and phosphate after phosphoric acid treatment. The ratio of zinc phosphate to zinc oxide was estimated from inductively coupled plasma - atomic emission spectroscopy results. Samples treated at pH 4-7 yielded small particles with sub-micrometer sizes. The photocatalytic activity of zinc oxide became lower after phosphoric acid treatment. Samples treated at pH 4-7 showed the same reflectance as zinc oxide in both the ultraviolet and visible ranges. Adjustment of the pH was found to be important in the phosphoric acid treatment of zinc oxide. (author)

  18. Activated carbon from peach stones using phosphoric acid activation at medium temperatures.

    Science.gov (United States)

    Kim, Dong-Su

    2004-01-01

    In the present study, the activation features of phosphoric acid have been investigated using waste peach stones as the raw material in the production of granular activated carbon. Thermogravimetry/differential thermal analysis was conducted to characterize the thermal behavior of peach stone and titration method was used to evaluate the adsorption capacity of the produced activated carbon. It was observed that the iodine value of the activated carbon increased with activation temperature. However, temperatures higher than 500 degrees C caused a thermal destruction, which resulted in the decrease of the adsorption capacity. Activation longer than 1.5 h at 500 degrees C resulted in thermal degradation of the porous structure of the activated carbon. The adsorption capacity was enhanced with increasing of amounts of phosphoric acid, however, excessive phosphoric acid caused a decrease in the iodine value. In addition, it was found that the carbon yields generally decreased with activation temperature and activation time. Scanning electron microscopy analysis was conducted to observe the changes in the poros structure of the activated carbon produced in different temperatures. Activation of carbon by phosphoric acid was found to be superior to that by CaCl2 and gas activation. The activated carbon produced from peach stone was applied as an adsorbent in the treatment of synthesized wastewater containing cadmium ion and its adsorption capacity was found to be as good as that of the commercial one.

  19. Measurement of the oxidation-extraction of uranium from wet-process phosphoric acid

    International Nuclear Information System (INIS)

    Lawes, B.C.

    1985-01-01

    The present invention relates to processes for the recovery of uranium from wet-process phosphoric acid and more particularly to the oxidation-extraction steps in the DEPA-TOPO process for such recovery. A more efficient use of oxidant is obtained by monitoring the redox potential during the extraction step

  20. A contribution to the study of mass transfer: uranium extraction from phosphoric acid

    International Nuclear Information System (INIS)

    Maher, A.

    1985-12-01

    Liquid-liquid extraction of uranium (VI) contained in phosphoric acid is examined. Synergism and thermodynamical equilibria are studied. Influence of drop size, extractant concentration and temperature on reaction kinetics are determined. The experimental study concerns extraction by HDEHP, TOPO and the mixture of both. Reaction mechanisms are interpreted [fr

  1. Effect of phosphoric acid as a catalyst on the hydrothermal pretreatment and acidogenic fermentation of food waste.

    Science.gov (United States)

    Shen, Dongsheng; Wang, Kun; Yin, Jun; Chen, Ting; Yu, Xiaoqin

    2016-05-01

    The hydrothermal method was applied to food waste (FW) pretreatment with phosphoric acid as a catalyst. The content of soluble substances such as protein and carbohydrate in the FW increased after the hydrothermal pretreatment with phosphoric acid addition (⩽5%). The SCOD approached approximately 29.0g/L in 5% phosphoric acid group, which is almost 65% more than the original FW. The hydrothermal condition was 160°C for 10min, which means that at least 40% of energy and 60% of reaction time were saved to achieve the expected pretreatment effect. Subsequent fermentation tests showed that the optimal dosage of phosphoric acid was 3% with a VFA yield of 0.763g/gVSremoval, but the increase in salinity caused by phosphoric acid could adversely affect the acidogenesis. With an increase in the quantity of phosphoric acid, among the VFAs, the percentage of propionic acid decreased and that of butyric acid increased. The PCR-DGGE analysis indicated that the microbial diversity could decrease with excessive phosphoric acid, which resulted in a low VFA yield. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Proton conductance at elevated temperature:Formulation and investigation of poly(4-styrenesulfonic acid / 4-aminobenzylamine / phosphoric acid membranes

    Directory of Open Access Journals (Sweden)

    Jalal eJalili

    2014-07-01

    Full Text Available 4-aminobenzylamine and phosphoric acid were blended in various proportions with poly (4-styrenesulfonic acid to form a new group of membranes exhibiting proton conductance under water-free conditions. The 4-aminobenzylamine molecule, possessing an aniline-like and benzylamine-like functional group, can interact both with the phosphoric acid and the poly(4-styrenesulfonic acid via nucleophilic interaction, thereby allowing proton jumping in the structure. Physico-chemical and thermal characteristics of the prepared solid membranes were investigated by IR spectroscopy and thermo-gravimetric analysis, respectively. Electrochemical impedance spectroscopy was employed to investigate their proton-conductance properties. Transparent composite membranes were prepared. However, the membranes are opaque for relatively high content of phosphoric acid. These membranes are thermally stable up to 300°C. The proton conductivity increases with temperature and also with content of phosphoric acid. Values as high as 1.8×10–3 S cm–1 were measured at 190°C in fully anhydrous condition.

  3. Development of an improved two-cycle process for recovering uranium from wet-process phosphoric acid

    International Nuclear Information System (INIS)

    Chen, H.M.; Chen, H.J.; Tsai, Y.M.; Lee, T.W.; Ting, G.

    1987-01-01

    An improved two-cycle separation process for the recovery of uranium from wet-process phosphoric acid by extraction with bis(2-ethylhexyl)phosphoric acid (D2EHPA) plus dibutyl butylphosphonate (DBBP) in kerosene has been developed and demonstrated successfully in bench-scale, continuous mixer-settler tests. The sulfuric acid and water scrubbing steps for the recycled extraction in the second cycle solve the problems of the contamination and dilution of the phosphoric acid by the ammonium ion and water and also avoid the formation of undesirable phosphatic precipitates during the subsequent extraction of uranium by recycled organic extractant

  4. The use of Syrian bentonite to remove organics and other ions from commercial Syrian phosphoric acid

    International Nuclear Information System (INIS)

    Khorfan, S.; Abdulbaki, M.; Zein, A.

    2005-03-01

    Using of activated carbon to remove organic matter from phosphoric acid in uranium and P 2 O 5 extraction units has high cost. A new study was conducted to establish a new material instead of activated carbon. Experiments were carried out on removing organic matter by adsorption on Syrian bentonite. The experiments of the removal of humic acid by Syrian bentonite gave good results and showed that the chemical and thermal activation of bentonite increased the adsorption efficiency. (Authors)

  5. Chiral Phosphoric Acid Catalyzed Diastereo- and Enantioselective Mannich-Type Reaction between Enamides and Thiazolones.

    Science.gov (United States)

    Kikuchi, Jun; Momiyama, Norie; Terada, Masahiro

    2016-06-03

    An enantioselective Mannich-type reaction between enamides, serving as aliphatic imine equivalents, and thiazolones or an azlactone, serving as α-amino acid derived pronucleophiles, was investigated using a chiral phosphoric acid catalyst. By using thiazolones, Mannich adducts with a tetrasubstituted chiral carbon center at the α-position and an aliphatic substituent at the β-position were efficiently obtained with high diastereo- and enantioselectivities.

  6. Phosphoric acid addition effect on the microstructure and magnetic properties of iron-based soft magnetic composites

    Science.gov (United States)

    Hsiang, Hsing-I.; Fan, Liang-Fang; Hung, Jia-Jing

    2018-02-01

    The phosphoric acid addition effect on phosphate insulation coating microstructure was investigated in this study. The relationships between the phosphate insulation coating microstructure and temperature resistance, corrosion resistance and magnetic properties of iron-based soft magnetic composites (SMCs) were studied by using SEM, TEM/EDS and FTIR. It was observed that an iron phosphate/carbonyl iron core/shell structure is formed with carbonyl iron powder after phosphatizing treatment. The iron phosphate phase was identified as amorphous and its thickness increased from 30 nm to 60 nm as the phosphoric acid concentration was increased from 1 wt% to 2 wt%. When the phosphoric acid concentration was further increased to 5 wt%, the excess iron phosphate precipitates between the soft magnetic composite particles. The temperature and corrosion resistance and resistivity of the iron-based SMCs can be effectively improved using carbonyl iron powders after phosphatizing. The initial permeability of the iron-based SMCs decreased with increasing phosphoric acid concentration due to thicker insulation layer formation. However, the imaginary permeability below the domain wall displacement resonance frequency decreased with increasing phosphoric acid concentration. The DC-bias superposition characteristic can also be improved by increasing the phosphoric acid concentration. Iron-based SMCs with superior temperature and corrosion resistance, initial permeability, magnetic loss and DC-bias superposition characteristics can be obtained by controlling the phosphoric acid concentration during phosphatizing to adjust the iron phosphate precipitate thickness on the iron powder surface.

  7. Developing a rapid method for the determination of uranium in pure phosphoric acid and D2 EHPA

    International Nuclear Information System (INIS)

    Koudsi, Y.; Stas, J.; Al-Merey, R.; shaddoud, G.

    1996-02-01

    Arsenazo (III) used in titrate uranium spectrophotometrically in phosphoric acid after its extraction into organic phase. In this work we used arsenazo(III) to complex uranyl ion in pure phosphoric acid and in the aqueous phase. The spectrum of the complex shows that λ max is at 650 nm. The linearity of the method is corelated with acid molarity, it is (1 -4, 10 - 30, 10 - 40) ppm uranium for (0.2, 1, 2) M of phosphoric acid respectively. Uranium in D 2 EHPA stripped by phosphoric acid and then determined by this method. Also it has been applied to determine uranium in pure perchloric acid. The method is direct, rapid, very cheap and relatively accurate. (author)

  8. Kinetic studies on uranium stripping in D2EHPA+TBP/phosphoric acid system

    International Nuclear Information System (INIS)

    Yadav, K.K.; Singh, D.K.; Kotekar, M.K.; Anitha, M.; Vijayalakshmi, R.; Singh, H.

    2010-01-01

    Full text: A novel process based on synergistic mixture of 1.5 M D2EHPA (di 2 ethyl hexyl phosphoric acid) + 0.2 M TBP (tri-n-butyl phosphate) to recover uranium from wet process phosphoric acid (WPA) has been developed. Though the equilibrium study for the above process has been investigated in detail its kinetic behavior has not been reported so far. The work presented in the paper is an attempt to study the kinetics of U(VI) stripping from extractant phase to aqueous phase in a constant interfacial area cell (Lewis cell). Kinetic study of the solvent extraction process helps in designing of equipment and optimizing process condition for the better utilization of solvent inventory. Mass transfer kinetics of stripping of U(VI) from loaded 1.5M D2EHPA+ 0.2M TBP with phosphoric acid (AR) has been studied over a wide range of experimental conditions such as stirring speed, interfacial contact area, phosphoric acid concentration, uranium concentration, extractant concentration in organic phase and temperature. Investigation on effect of stirring speed (100-500 rpm) on stripping of U(VI) showed that the rate constant (k) values increases linearly with increase in stirring speeds from 100 to 300 rpm (0.03 to 0.075 cm/min), while the k values were almost constant (0.0819 cm/min) in 300 to 400 rpm range, beyond 450 rpm the k values again increased due to increased turbulence at the interface. The rate constant value (∼0.0814 cm/min) was found to be independent of interfacial contact area (24.6 to 67.02 cm 2 ) available for mass transfer. The rate constants were found to increase with increase in phosphoric acid concentration (6-10M) and temperature (30-60 deg C), the values being in the range of 0.01 to 0.082 cm/min. The slopes of ln-ln plot showed that the stripping of U(VI) has a second order dependence on phosphoric acid concentration (slope∼2) at temperatures ranging from 30 to 60 deg C. The activation energy value for uranium stripping was found to be in the

  9. Carbon-13 kinetic isotope effects in the decarbonylation of lactic acid of natural isotopic composition in phosphoric acid medium

    International Nuclear Information System (INIS)

    Zielinski, M.; Czarnota, G.; Papiernik-Zielinska, H.; Kasprzyk, G.; Gumolka, L.; Staedter, W.

    1993-01-01

    The 13 C kinetic isotope effect fractionation in the decarbonylation of lactic acid (LA) of natural isotopic composition by concentrated phosphoric acids (PA) and by 85% H 3 PO 4 has been studied in the temperature interval of 60-150 deg C. The values of the 13 C (1) isotope effects in the decarbonylation of lactic acid in 100% H 3 PO 4 , in pyrophosphoric acid and in more concentrated phosphoric acids are intermediate between the values calculated assuming that the C (1)- OH bond is broken in the rate-controlling step of dehydration and those calculated for rupture of the carbon-carbon bond in the transition state. In the temperature interval of 90-130 deg C the experimental 13 C fractionation factors determined in concentrated PA approach quite closely the 13 C fractionation corresponding to C (2)- C (1) bond scission. The 13 C (1) kinetic isotope effects in the decarbonylation of LA in 85% orthophosphoric acid in the temperature range of 110-150 deg C coincide with the 13 C isotope effects calculated assuming that the frequency corresponding to the C (1) -OH vibration is lost in the transition state of decarbonylation. A change of the mechanism of decarbonylation of LA in going from concentrated PA medium to 85% H 3 PO 4 has been suggested. A possible secondary 18 O and a primary 18 O kinetic isotope effect in decarbonylation of lactic acid in phosphoric acids media have been discussed, too. (author) 21 refs.; 3 tabs

  10. Electrolyte for phosphoric acid fuel cell. Rinsangata nenryo denchi no denkaieki

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Y.; Uede, M.; Yamaken, H. (Yamaha Motor Co. Ltd., Shizuoka (Japan))

    1991-02-14

    When the phosphoric fuel cell is used in cold districts, the electrolyte used in the cell solidifies and freezes because its freezing point is high, and the cell can not be used any more. The object of this invention is to provide a fuel cell which does not freeze even the cell is shutdown in low temperature environment by adding non-conjugating inorganic salt to strong phosphoric acid to lower the freezing point. The phosphoric acid used in accordance with this invention is desirable generally to be of 80 to 105% if calculated in terms of orthophosphoric acid to maintain the cell performance. As the negative ions constituting the non-conjugating inorganic salt, sulphate ion, carbonate ion, silicate ion, and boric acid ion are desirable. In concrete, ZnSO{sub 4}, NiSO{sub 4}, Na{sub 2}SO{sub 4}, BeSO{sub 4}, CdSO{sub 4}, CoSO{sub 4}, FeSO{sub 4}, K{sub 2}CO{sub 3}, Na{sub 2}CO{sub 3}, CaCO{sub 3}, MgCO{sub 3}, K{sub 2}SiO{sub 3}, Na{sub 2}B{sub 4}O{sub 7}, etc. can be quoted. Excessive addition of inorganic salt results rather in the precipitation of the added inorganic salt to cause freezing, and addition of 20wt% or less is desirable. 1 fig.

  11. Inorganic-Organic hybrid materials for uranium extraction from phosphoric acid

    International Nuclear Information System (INIS)

    El-Mourabit, Sabah

    2013-01-01

    Phosphate rocks are industrially processed in large quantities to produce phosphoric acid and fertilisers. These rocks contain significant concentration of uranium (50 to 300 ppm) which could be interesting for nuclear industry. This work deals with the valorisation of uranium as a by-product from fertiliser industry. The aim of this study is to develop a hybrid material, constituted of an inorganic solid support grafted with an extractant (complexing molecule), which can extract selectively uranium from phosphoric acid medium. The first step of our approach was to identify an inorganic support which is stable under these particular conditions (strong acidity and complexing medium). The chemical and mechanical stability of different meso-porous materials, such as silica, glass and carbon was studied. In a second phase, we focused on the identification and the optimisation of complexing molecules, specific of uranium in phosphoric acid. These ligands were then grafted on the most stable solids. Finally, the efficiency of these hybrid systems was evaluated through different tests of extraction, selectivity and de-extraction. (author) [fr

  12. Revised Theoretical Model on Enantiocontrol in Phosphoric Acid Catalyzed H-Transfer Hydrogenation of Quinoline.

    Science.gov (United States)

    Pastor, Julien; Rezabal, Elixabete; Voituriez, Arnaud; Betzer, Jean-François; Marinetti, Angela; Frison, Gilles

    2018-03-02

    The enantioselective H-transfer hydrogenation of quinoline by Hantzsch ester is a relevant example of Brønsted acid catalyzed cascade reactions, with phosphoric acid being a privileged catalyst. The generally accepted mechanism points out the hydride transfer step as the rate- and stereodetermining step, however computations based on these models do not totally fit with experimental observations. We hereby present a computational study that enlightens the stereochemical outcome and quantitatively reproduces the experimental enantiomeric excesses in a series of H-transfer hydrogenations. Our calculations suggest that the high stereocontrol usually attained with BINOL-derived phosphoric acids results mostly from the steric constraints generated by an aryl substituent of the catalyst, which hinders the access of the Hantzsch ester to the catalytic site and enforces approach through a specific way. It relies on a new model involving the preferential assembly of one of the stereomeric complexes formed by the chiral phosphoric acid and the two reaction partners. The stereodetermining step thus occurs prior to the H-transfer step.

  13. Solid phase extraction of uranium from phosphoric acid. Kinetic and thermodynamic study

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Magied, Ahmed Fawzy [Nuclear Materials Authority, Cairo (Egypt); Stockholm Univ. (Sweden). Dept. of Organic Chemistry

    2017-07-01

    There is a high interest to develop suitable solid phase extractants for uranium separation from aqueous solutions in order to reduce cost and enhance the efficiency. This paper describes solid phase extraction of uranium(VI) from aqueous phosphoric acid solution using MCM-41 based D2HEPA-TOPO organophosphorous extractants. The mixture of D2HEPA (di-2-ethyl-hexylphosphoric acid) and TOPO (tri-n-octylphosphine oxide) was impregnated into the pores of MCM-41 and the synthesized sorbent was fully characterized. The influences of different factors such as synergistic mixture ratio, phosphoric acid concentration, mixing time and temperature were investigated. The results showed that 90% of uranium(VI) extraction can be achieved within 5 min, using D2HEPA-TOPO rate at MCM-41 (mass ratio 2:1 w/w) from 1 M phosphoric acid containing 64 ppm of uranium at room temperature. High adsorption capacity of uranium(VI) have been achieved at the mentioned conditions. The rate constant for the chemical adsorption of uranium(VI) was 0.988 g mg{sup -1} min{sup -1} calculated by the pseudo-second order rate equation. The obtained thermodynamics parameters showed that uranium(VI) adsorption from H{sub 3}PO{sub 4} is an exothermic and spontaneous process.

  14. Analytical applications of condensed phosphoric acid-I Determination of ferrous and total iron in iron ores after decomposition with condensed phosphoric acid.

    Science.gov (United States)

    Mizoguchi, T; Ishii, H

    1978-06-01

    A simple method is described for the determination of ferrous and total iron in iron ores. Iron ores are dissolved by condensed phosphoric acid (CPA) very rapidly without any tedious and time-consuming manipulations such as elimination of silica and filtration. Under the proposed conditions (amount of sample 100 mg, amount of CPA added 10 g, heating temperature 290 degrees , heating time 30 min), magnetite, limonite and hematite are completely dissolved. The iron content can be determined in the presence of condensed phosphoric acid by titration with dichromate solution, if a slight modification is made. The total iron in iron ores, determined by the present method, is in agreement with that found by the JIS method. The ferrous iron in iron ores can be determined by dissolving the samples with CPA in a nitrogen atmosphere and titrating with dichromate solution. Chelatometric titration of iron after solvent extraction with MIBK from solutions prepared by use of CPA is found to be accurate for samples such as pyrite cinder. The ability of CPA to dissolve various materials has been investigated.

  15. Effect of structure on extraction ability of phosphoric acid amides

    International Nuclear Information System (INIS)

    Laskorin, B.N.; Buchikhin, E.P.; Yakshin, V.V.

    1976-01-01

    Effective constants of uranium (6) extraction with amides and esteroamides based on the acids of phosphorus of various structures have been determined. The component analysis of the complexes obtained points to the formation of a compound with the metal/ligand ratio = 2. The introduction of alkyl amine substituents in the molecule of the neutral esters of organophosphoric acids is shown to lead to a substantial increase in their extraction capacity [ru

  16. Potentiality of uranium adsorption from wet phosphoric acid using amine-impregnated cellulose

    Directory of Open Access Journals (Sweden)

    Ahmed H. Orabi

    2016-04-01

    In the present work, two working solutions were used. The first solution was a synthesized phosphoric acid (35% P2O5 and 100 ppm U used for optimizing the loading process of uranium. The second one was used as a case study for adsorption of uranium from a real phosphoric acid (WPPA prepared from El-Sebaiya phosphate ore (P2O5 35%, 100 ppm U. The obtained equilibrium data were found to be satisfactory fitted with Langmuir isotherm. A maximum-metal uptake of 56.5 mgU/g AIC was observed at the obtained optimum conditions. Also, elution process of uranium has been achieved at 1 M of 30 ml Na2CO3 solution/g AIC after 15 min contact time. From the latter, a marketable product of sodium di-uranate was prepared.

  17. Properties of the Surface Layer of Thin Films of Polyaniline Doped With Phosphoric Acid

    Directory of Open Access Journals (Sweden)

    Almedina Modrić-Šahbazović

    2016-08-01

    Full Text Available This study deals with estimation of the surface free energy of thin films of polyaniline doped with phosphoric acid, by measuring contact angles. Synthesis of polyaniline (PANI with phosphoric acid (PA was performed at room temperature of 20°C, and at 0°C. Thin films were obtained by means of a spin coater, applying the synthetized mixture on a glass substrate. By measuring the contact angle, first between ethylene glycol and a film and then between distilled water and a film, we thus calculated the polar, dispersion and total surface free energy. It was proved and demonstrated that the surface free energy depends on the temperature at which the solution (from which the thin films are obtained later was synthesized.

  18. Ionic flotation of uranium and of cadmium in concentrated phosphoric acid media

    International Nuclear Information System (INIS)

    Jdid, E.; Bessiere, J.; Blazy, P.

    1984-01-01

    The ionic flotation technique has been applied to concentrated phosphoric acid media (with 30% P 2 O 5 or H 3 PO 4 5.5 M) as a new process for the recovery of uranium and the elimination of cadmium. The results obtained seem to indicate that in these hyperacid media the anionic collectors are better suited than the cationic collectors and that they then permit the flotation of the uranium and cadmium ions with a very rapid kinetics and the achievement of efficiencies of over 90%. In the case of uranium, the collector used remains efficient up to a temperature of 60 0 C with a satisfactory selectivity in the face of others cations present in the commercial phosphoric acid, and which have a penalizing effect on the uraniferous concentrates, and the floated uranium concentrate assays approximately 10% U on a dry basis [fr

  19. Structural and morphological changes in supramolecular-structured polymer electrolyte membrane fuel cell on addition of phosphoric acid

    Science.gov (United States)

    Hendrana, S.; Pryliana, R. F.; Natanael, C. L.; Rahayu, I.

    2018-03-01

    Phosphoric acid is one agents used in membrane fuel cell to modify ionic conductivity. Therefore, its distribution in membrane is a key parameter to gain expected conductivity. Efforts have been made to distribute phosphoric acid in a supramolecular-structured membrane prepared with a matrix. To achieve even distribution across bulk of the membrane, the inclusion of the polyacid is carried out under pressurized chamber. Image of scanning electron microscopy (SEM) shows better phosphoric acid distribution for one prepared in pressurized state. It also leads in better performing in ionic conductivity. Moreover, data from differential scanning calorimetry (DSC) indicate that the addition of phosphoric acid is prominent in the change of membrane structure, while morphological changes are captured in SEM images.

  20. Method for the recovery of uranium from phosphoric acid, originating from the wet-process of uraniferous phosphate ores

    International Nuclear Information System (INIS)

    Pyrih, R.Z.; Rickard, R.S.; Carrington, O.F.

    1978-01-01

    Improvement in the process for recoverying uranium from wet-process phosphoric acid solution derived from the acidulation of uraniferous phosphate ores by the use of two ion exchange circuits is described. (Auth.)

  1. Evaluation of two processes for the production of phosphoric acid in pilot scale

    International Nuclear Information System (INIS)

    Santos Benedetto, J. dos.

    1984-01-01

    Two processes for the production of phosphoric acid, based on dihydrate route and hemihydrate route, have been evaluated. The processes were tested in a pilot plant using the concentrate obtained from phosphorus-uraniferous mineral from Itataia mines (CE, Brazil). Results were evaluated from the data obtained from phosphorus and uranium solubilizations. Also presented, although in a summarised way, are the description of the construction of the pilot plants and the analytical methods for the follow-up of processes. (Author) [pt

  2. Separation of transuranium elements from high-level waste by extraction with diisodecyl phosphoric acid

    International Nuclear Information System (INIS)

    Morita, Y.; Kubota, M.; Tani, S.

    1991-01-01

    Separation of transuranic elements (TRU) by extraction with diisodecyl phosphoric acid (DIDPA) has been studied to develop a partitioning process for high-level waste (HLW). In the present study, experiments of counter-current continuous extraction and back-extraction using a miniature mixer-settler were carried out to find the optimum process condition for the separation of Np initially in the pentavalent state and to examine the extraction behaviors of fission and corrosion products. (J.P.N.)

  3. Gel Electrolytes of Covalent Network Polybenzimidazole and Phosphoric Acid by Direct Casting

    DEFF Research Database (Denmark)

    Kirkebæk, Andreas; Aili, David; Henkensmeier, Dirk

    2017-01-01

    Polybenzimidazole membranes imbibed with phosphoric acid can support high proton conductivity at 120–200 °C, and have therefore emerged as the state-of-the-art electrolytes for fuel cells operating in this temperature range. This work presents a novel and operationally simple methodology...... at up to 230 °C, yielding free-standing membranes of networked polybenzimidazole with high proton conductivity at up to 180 °C and encouraging fuel cell performance...

  4. Purification of wet process phosphoric acid by decreasing iron and uranium using white silica sand

    Energy Technology Data Exchange (ETDEWEB)

    El-Bayaa, A.A., E-mail: amina.elbayaa@yahoo.com [Chemistry Department, Faculty of Science, Al-Azhar University (Girls), Nasr City, Cairo (Egypt); Badawy, N.A.; Gamal, A.M.; Zidan, I.H.; Mowafy, A.R. [Chemistry Department, Faculty of Science, Al-Azhar University (Girls), Nasr City, Cairo (Egypt)

    2011-06-15

    Natural white silica sand as an adsorbent has been developed to reduce the concentration of iron and uranium ions as inorganic impurities in crude Egyptian phosphoric acid. Several parameters such as adsorbate concentration, adsorbent dose, volume to weight ratio and temperature, were investigated. Equilibrium isotherm studies were used to evaluate the maximum sorption capacity of adsorbent. Thermodynamic parameters showed the exothermic nature of the process and the negative entropy reflects the affinity of the adsorbent material towards each metal ion.

  5. Effect of acetic acid on wet patterning of copper/molybdenum thin films in phosphoric acid solution

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Bo.-Hyun; Lee, Sang-Hyuk; Park, In-Sun [Department of Materials Engineering, Korea Aerospace University, Hwajeon, Goyang, Gyonggi-do 412-791 (Korea, Republic of); Seo, Jong Hyun, E-mail: jhseo@kau.ac.kr [Department of Materials Engineering, Korea Aerospace University, Hwajeon, Goyang, Gyonggi-do 412-791 (Korea, Republic of); Choe, HeeHwan; Jeon, Jae-Hong [School of Electronics, Telecommunications and Computer Engineering, Korea Aerospace University, Hwajeon, Goyang, Gyonggi-do 412-791 (Korea, Republic of); Hong, Munpyo [Display and Semiconductor Physics, Korea University (Korea, Republic of); Lee, Yong Uk [PETEC (The Printable Electronics Technology Centre) (United Kingdom); Winkler, Joerg [PLANSEE Metal GmbH, Metallwerk-Plansee-Str. 71A-6600, Reutte (Austria)

    2011-08-01

    Copper metallization is a key issue for high performance thin film transistor (TFT) technology. A phosphoric acid based copper etchant is a potentially attractive alternative to the conventional hydrogen peroxide based etchant due to its longer-life expectancy time and higher stability in use. In this paper, it is shown that amount of the acetic acid in the phosphoric based copper etchant plays an important role in controlling the galvanic reaction between the copper and the molybdenum. As the concentration of acetic acid in the phosphoric mixture solution increased from 0 M to 0.4 M, the measured galvanic current density dropped from 32 mA/cm{sup 2} to 26 mA/cm{sup 2}, indicating that the acetic acid induces the lower galvanic reaction between the copper and the molybdenum in the solution. From the XPS analysis, with the addition of the acetic acid, the thickness of the protective MoO{sub 2} passive film covering the molybdenum surface grew and the dissolution rate of the molybdenum thin film decreased. However, the dissolution rate of the copper thin film increased as the concentration of acetic acid in the mixture solution increased.

  6. Effect of acetic acid on wet patterning of copper/molybdenum thin films in phosphoric acid solution

    International Nuclear Information System (INIS)

    Seo, Bo.-Hyun; Lee, Sang-Hyuk; Park, In-Sun; Seo, Jong Hyun; Choe, HeeHwan; Jeon, Jae-Hong; Hong, Munpyo; Lee, Yong Uk; Winkler, Joerg

    2011-01-01

    Copper metallization is a key issue for high performance thin film transistor (TFT) technology. A phosphoric acid based copper etchant is a potentially attractive alternative to the conventional hydrogen peroxide based etchant due to its longer-life expectancy time and higher stability in use. In this paper, it is shown that amount of the acetic acid in the phosphoric based copper etchant plays an important role in controlling the galvanic reaction between the copper and the molybdenum. As the concentration of acetic acid in the phosphoric mixture solution increased from 0 M to 0.4 M, the measured galvanic current density dropped from 32 mA/cm 2 to 26 mA/cm 2 , indicating that the acetic acid induces the lower galvanic reaction between the copper and the molybdenum in the solution. From the XPS analysis, with the addition of the acetic acid, the thickness of the protective MoO 2 passive film covering the molybdenum surface grew and the dissolution rate of the molybdenum thin film decreased. However, the dissolution rate of the copper thin film increased as the concentration of acetic acid in the mixture solution increased.

  7. Effect of phosphoric acid etching on the shear bond strength of two self-etch adhesives

    Directory of Open Access Journals (Sweden)

    Camila SABATINI

    2013-01-01

    Full Text Available Objective To evaluate the effect of optional phosphoric acid etching on the shear bond strength (SBS of two self-etch adhesives to enamel and dentin. Material and Methods Ninety-six bovine mandibular incisors were ground flat to obtain enamel and dentin substrates. A two-step self-etch adhesive (FL-Bond II and a one-step self-etch adhesive (BeautiBond were applied with and without a preliminary acid etching to both the enamel and dentin. The specimens were equally and randomly assigned to 4 groups per substrate (n=12 as follows: FL-Bond II etched; FL-Bond II un-etched; BeautiBond etched; BeautiBond un-etched. Composite cylinders (Filtek Z100 were bonded onto the treated tooth structure. The shear bond strength was evaluated after 24 hours of storage (37°C, 100% humidity with a testing machine (Ultra-tester at a speed of 1 mm/min. The data was analyzed using a two-way ANOVA and post-hoc Tukey's test with a significance level of p<0.05. A field emission scanning electron microscope was used for the failure mode analysis. Results Both adhesives evidenced a significant decrease in the dentin SBS with the use of an optional phosphoric acid-etching step (p<0.05. Preliminary phosphoric acid etching yielded significantly higher enamel SBS for FL-Bond II (p<0.05 only, but not for BeautiBond. FL-Bond II applied to un-etched dentin demonstrated the highest mean bond strength (37.7±3.2 MPa and BeautiBond applied to etched dentin showed the lowest mean bond strength (18.3±6.7 MPa among all tested groups (p<0.05. Conclusion The use of a preliminary acid-etching step with 37.5% phosphoric acid had a significant adverse effect on the dentin bond strength of the self-etch adhesives evaluated while providing improvement on the enamel bond strength only for FL-Bond II. This suggests that the potential benefit that may be derived from an additional etching step with phosphoric acid does not justify the risk of adversely affecting the bond strength to dentin.

  8. Complexity in Acid–Base Titrations: Multimer Formation Between Phosphoric Acids and Imines

    Science.gov (United States)

    Malm, Christian; Kim, Heejae; Wagner, Manfred

    2017-01-01

    Abstract Solutions of Brønsted acids with bases in aprotic solvents are not only common model systems to study the fundamentals of proton transfer pathways but are also highly relevant to Brønsted acid catalysis. Despite their importance the light nature of the proton makes characterization of acid–base aggregates challenging. Here, we track such acid–base interactions over a broad range of relative compositions between diphenyl phosphoric acid and the base quinaldine in dichloromethane, by using a combination of dielectric relaxation and NMR spectroscopy. In contrast to what one would expect for an acid–base titration, we find strong deviations from quantitative proton transfer from the acid to the base. Even for an excess of the base, multimers consisting of one base and at least two acid molecules are formed, in addition to the occurrence of proton transfer from the acid to the base and simultaneous formation of ion pairs. For equimolar mixtures such multimers constitute about one third of all intermolecular aggregates. Quantitative analysis of our results shows that the acid‐base association constant is only around six times larger than that for the acid binding to an acid‐base dimer, that is, to an already protonated base. Our findings have implications for the interpretation of previous studies of reactive intermediates in organocatalysis and provide a rationale for previously observed nonlinear effects in phosphoric acid catalysis. PMID:28597513

  9. Nitric-phosphoric acid oxidation of solid and liquid organic materials

    International Nuclear Information System (INIS)

    Pierce, R.A.; Smith, J.R.; Poprik, D.C.

    1995-01-01

    Nitric-phosphoric acid oxidation has been developed specifically to address issues that face the Savannah River Site, other defense-related facilities, private industry, and small-volume generators such as university and medical laboratories. Initially tested to destroy and decontaminate SRS solid, Pu-contaminated job-control waste, the technology has also exhibited potential for remediating hazardous and mixed-hazardous waste forms. The process is unique to Savannah River and offers a valuable alternative to other oxidation processes that require extreme temperatures and/or elevated pressures. To address the broad categories of waste, many different organic compounds which represent a cross-section of the waste that must be treated have been successfully oxidized. Materials that have been quantitatively oxidized at atmospheric pressure below 180 degrees C include neoprene, cellulose, EDTA, tributylphosphate, and nitromethane. More stable compounds such as benzoic acid, polyethylene, oils, and resins have been completely decomposed below 200 degrees C and 10 psig. The process uses dilute nitric acid in a concentrated phosphoric acid media as the main oxidant for the organic compounds. Phosphoric acid allow nitric acid to be retained in solution well above its normal boiling point. The reaction forms NOx vapors which can be reoxidized and recycled using air and water. The addition of 0.001M Pd(II) reduces CO generation to near 1% of the released carbon gases. The advantages of this process are that it is straightforward, uses relatively inexpensive reagents, operates at relatively low temperature and pressure, and produces final solutions which are compatible with stainless steel equipment. For organic wastes, all carbon, hydrogen, and nitrogen are converted to gaseous products. If interfaced with an acid recovery system which converts NOx back to nitric acid, the net oxidizer would be oxygen from air

  10. Actinium extraction with di(2-ethylhexyl)phosphoric acid

    International Nuclear Information System (INIS)

    Karalova, Z.K.; Rodionova, L.M.; Pyzhova, Z.I.; Myasoedov, B.F.

    1978-01-01

    The extraction of actinium with hdehp from HNO 3 and HClO 4 solutions has been studied in a wide range of acid concentrations. Radioactive Ac 228 has been used as a tracer. Benzene and n-octane have been used as solvents. It has been established that Ac is extracted quantitatively with 0.5 mhdehp in n-octane at HNO 3 concentration -2 M and HClO 4 ( -2 M. Actinium extraction from 8.5 M HClO 4 is 94.7%. The mechanism of actinium extraction has been considered. The composition of the extracted compounds was established, the extraction constant was determined. The most probable form of actinium existance in an organic phase upon extraction from weakly acid solutions is a Asub(c)Xsub(3)x2HX complex and from strongly acid solutions - a solvated complex acid of the HAc(ClO 4 ) 4 x2HX type (where HX - is hdehp)

  11. Extractants for uranium recovery from wet phosphoric acid

    International Nuclear Information System (INIS)

    Musikas, C.; Benjelloun, N.; Lours, S.

    1981-08-01

    It must be pointed out that despite their lower affinity for uranyl, the dialkyldithiophosphates show higher extraction coefficients than dialkylphosphates. In addition, it is possible to back extract uranium with oxalate solutions at pH levels where the solvents remain in their acidic form. This last possibility seems to be correlated with the presence of a H 2 PO 4 - ion in the U(VI) organic complexes

  12. Electrochemistry of Phosphorous and Hypophosphorous Acid on a Pt electrode

    International Nuclear Information System (INIS)

    Prokop, M.; Bystron, T.; Bouzek, K.

    2015-01-01

    Highlights: • H 3 PO 3 and H 3 PO 2 oxidation on Pt electrode proceed at high overpotential. • H 3 PO 2 oxidation proceeds via H 3 PO 3 as intermediate. • H 3 PO 3 and H 3 PO 2 adsorb on Pt electrode, adsorption isotherms determined. • Adsorption is more pronounced at elevated temperature. • Tautomeric equilibria plays an important role in the acids behaviour. - Abstract: H 3 PO 4 is commonly used as a proton-conducting phase in high temperature proton exchange membrane fuel cell membranes. However, its reduction with hydrogen at elevated temperatures yields compounds like H 3 PO 3 and phosphorus. The aim of this work was to describe the basic electrochemical behaviour of H 3 PO 3 and H 3 PO 2 on a Pt electrode in diluted aqueous H 2 SO 4 solutions. The results show that adsorption of both phosphorus acids studied becomes important at an oxoacid bulk concentration around and below 10 mol dm −3 . Adsorption isotherms at 25 and 70 °C were determined for both acids. Unusually, the extent of adsorption increases with rising temperature. H 3 PO 3 is anodically oxidised on a bare Pt as well as on a PtO surface. H 3 PO 2 oxidation proceeds mainly on a PtO surface, with the intermediate product being H 3 PO 3 . High overvoltage around 1 V is characteristic of all anodic oxidation reactions occurring in the temperature range studied

  13. Optimization of Butylphosphate synthesis from O-Phosphoric Acid

    International Nuclear Information System (INIS)

    Amedjkouh, A.; Attou, M.; Azzouz, A.; Zaoui, B.

    1995-07-01

    This work was carried out in order to confirm results of previous work and to enhance the yield of TBP synthesis. This, many reactions have been realised under differents experimental condition (temperature, acid/ alcool molar ratio, pressure and the quantity of promoter agent 'POCL3'). the TBP yield variations as function the experimental parameters, has been expressed, using the 2n factorial plan mathematical model. The experimental results were compared to those given by the theoritical model, and the optimal conditions were then drawn out

  14. Porous structure and surface chemistry of phosphoric acid activated carbon from corncob

    Science.gov (United States)

    Sych, N. V.; Trofymenko, S. I.; Poddubnaya, O. I.; Tsyba, M. M.; Sapsay, V. I.; Klymchuk, D. O.; Puziy, A. M.

    2012-11-01

    Active carbons have been prepared from corncob using chemical activation with phosphoric acid at 400 °C using varied ratio of impregnation (RI). Porous structure of carbons was characterized by nitrogen adsorption and scanning electron microscopy. Surface chemistry was studied by IR and potentiometric titration method. It has been shown that porosity development was peaked at RI = 1.0 (SBET = 2081 m2/g, Vtot = 1.1 cm3/g), while maximum amount of acid surface groups was observed at RI = 1.25. Acid surface groups of phosphoric acid activated carbons from corncob includes phosphate and strongly acidic carboxylic (pK = 2.0-2.6), weakly acidic carboxylic (pK = 4.7-5.0), enol/lactone (pK = 6.7-7.4; 8.8-9.4) and phenol (pK = 10.1-10.7). Corncob derived carbons showed high adsorption capacity to copper, especially at low pH. Maximum adsorption of methylene blue and iodine was observed for carbon with most developed porosity (RI = 1.0).

  15. 37% Phosphoric Acid Induced Stronger Matrix Metalloproteinase-8 Expression of the Dental Pulp than 19% Ethylene Diamine Tetraacetic Acid

    Directory of Open Access Journals (Sweden)

    Nadie Fatimatuzzahro

    2014-11-01

    Full Text Available Etching agents such as ethylene diamine tetraacetic acid (EDTA and phosphoric acid which are widely used in adhesive restoration system aimed to increase for retention of restorative materials, may act a chemical irritant that induce inflammation of dental pulp. Inflammation is a body response against irritant and infectious agents. Matrix metalloproteinase-8, the major collagenolytic enzyme, degrades collagen type 1. This enzyme is expressed in low level in normal condition, however, the expression will increase during inflammation. The purpose of the present research was to study the effect of 19% EDTA and 37% phosphoric acid application as an etching agents on the MMP-8 expression of dental pulp. Forty-five male Sprague Dawley rats were divided into 3 groups. Cavity preparation was made on the occlusal surface of maxillary first molar using a round diamond bur. 19% EDTA, 37% phosphoric acid, and distilled water were applied on the surface of the cavity of the teeth in group I, II, and III subsequently. The cavity then filed by glass ionomer cements. The rats were sacrified at 1, 3, 5, 7, and 14 days after the treatment (n=3 for each day. The specimens were then processed histologically. Immunohistochemical (IHC analysis was performed using rabbit anti rat MMP-8 polyclonal antibody to examine MMP-8 expression and HE (Hematoxylen Eosin staining to observe the number of macrophages. The results showed 37% phosphoric acid application induced stronger expression of MMP-8 and higher number of macrophages than 19% EDTA. The strongest expression of MMP-8 seems on 5 days after the treatment where the highest number of macrophages were also found.

  16. Use of a pulsed column with discs and crowns for uranium extraction from phosphoric acid

    International Nuclear Information System (INIS)

    1982-04-01

    The physico-chemistry of the system phosphoric acid-uranium-dioctylpyrophosphoric acid is studied for the determination of analytical methods and extraction parameters (oxidation state of uranium and iron, phosphorus concentration, extractant concentration). Extraction is then realized on a pilot scale with a liquid-liquid extraction column 4m high and of 50 mm in diameter with a column packing made of discs and crowns. Column efficiency is evaluated by studying uranium transfer as a function of operating conditions. The results obtained are extrapolated to an industrial scale and a comparative economic evaluation is made between a pulsed column and a mixer-settler [fr

  17. The extraction of uranium from wet process phosphoric acid using a liquid surfactant membrane system

    International Nuclear Information System (INIS)

    Dickens, N.; Davies, G.A.

    1984-01-01

    A liquid membrane extraction process is examined for the extraction of uranium from wet process phosphoric acid. Uranium is present in the acid in concentrations up to 100 ppm which in principle makes it ideal for treatment with a membrane process. The membrane system studied is based on extraction using DEHPA-TOPO reagents which are contained within the organic phase of a water in oil emulsion. Formulations of the emulsion membrane system have been studied, the limitations of acid temperature, P 2 O 5 concentration and solid dispersed impurities in the acid have been studied in laboratory batch experiments and in a continuous pilot plant unit capable of treating 5l of concentrated acid per minute. Data from the pilot plant work has been used to develop a flowsheet for a commercial unit based on this process. (author)

  18. Extraction of indium from sulfuric acid solutions by mixture of di-(2-ethylhexyl)phosphoric and caprylic acids

    International Nuclear Information System (INIS)

    Flejtlikh, I.Yu.; Pashkov, G.L.; Nikiforova, L.K.; Grigor'eva, N.A.; Pavlenko, N.I.; Kolesnichenko, G.V.; Stoyanov, E.S.; Makarov, I.V.; Khol'kin, A.I.

    2001-01-01

    Data on indium extraction from sulfuric acid solutions by mixtures of di-(2-ethylhexyl)phosphoric acid (HR) and caprylic acid (HA) are presented. By the methods of IR spectroscopy state of HR in HA is investigated. It is shown that imperfection in this system is described by the processes of partial HR dimerization in organic phase. During indium extraction there is strong antagonistic effect caused by interaction HR and HA because of formation of intermolecular hydrogen bonds. In the case of low indium concentration and big excess of extractant formation of In(HR 2 ) 3 takes place in organic phase as is in the case of application of inert diluents [ru

  19. The Comparison of Hydrochloric Acid and Phosphoric Acid Treatments in the Preparation of Montmorillonite Catalysts for RNA Synthesis

    Science.gov (United States)

    Aldersley, Michael Frank; Joshi, Prakash C.; Huang, Yixing

    2017-09-01

    The treatment of clay minerals with a preliminary acid wash and titration to pH 7 has proven to generate catalysts for the most interesting of oligomerization reactions in which activated RNA-nucleotides generate oligomers up to 40-mers. Significantly, not all clay minerals become catalytic following this treatment and none are catalytic in the absence of such treatment. The washing procedure has been modified and explored further using phosphoric acid and the outcomes are compared to those obtained when clay samples are prepared following a hydrochloric acid wash.

  20. The Comparison of Hydrochloric Acid and Phosphoric Acid Treatments in the Preparation of Montmorillonite Catalysts for RNA Synthesis.

    Science.gov (United States)

    Aldersley, Michael Frank; Joshi, Prakash C; Huang, Yixing

    2017-09-01

    The treatment of clay minerals with a preliminary acid wash and titration to pH 7 has proven to generate catalysts for the most interesting of oligomerization reactions in which activated RNA-nucleotides generate oligomers up to 40-mers. Significantly, not all clay minerals become catalytic following this treatment and none are catalytic in the absence of such treatment. The washing procedure has been modified and explored further using phosphoric acid and the outcomes are compared to those obtained when clay samples are prepared following a hydrochloric acid wash.

  1. Proton conductivity of phosphoric acid doped polybenzimidazole and its composites with inorganic proton conductors

    DEFF Research Database (Denmark)

    He, Ronghuan; Qingfeng, Li; Gang, Xiao

    2003-01-01

    Phosphoric acid doped polybenzimidazole (PBI) and PBI composite membranes have been prepared in the present work. The PBI composites contain inorganic proton conductors including zirconium phosphate (ZrP), (Zr(HPO4)2·nH2O), phosphotungstic acid (PWA), (H3PW12O40·nH2O) and silicotungstic acid (Si......WA), (H4SiW12O40·nH2O). The conductivity of phosphoric acid doped PBI and PBI composite membranes was found to be dependent on the acid doping level, relative humidity (RH) and temperature. A conductivity of 6.8×10−2 S cm−1 was observed for PBI membranes with a H3PO4 doping level of 5.6 (mole number of H3......PO4 per repeat unit of PBI) at 200 ◦C and 5% RH. A higher conductivity of 9.6×10−2 S cm−1 was obtained by composite of 15 wt.% of ZrP in a PBI membrane under the same conditions. Homogeneous membranes with good mechanical strength were prepared by introducing PWA (20–30 wt.%) and SiWA (20–30 wt...

  2. Proton conductivity of phosphoric acid doped polybenzimidazole and its composites with inorganic protontic conductors

    DEFF Research Database (Denmark)

    Li, Qingfeng

    2003-01-01

    Polymer electrolytes have received considerable attention, especially for polymer electrolyte membrane fuel cells (PEMFCs) operating at temperatures above 100°C. phosphoric acid doped polybenzimidazole (PBI) and PBI composite membranes have been prepared in the present work. The PBI composites...... contain inorganic protonic conductors including zirconium phosphate (ZrP), (Zr(HPO4)2. nH2O); phosphotungstic acid (PWA), (H3PW12O40. nH2O); and silicotungstic acid (SiWA), (H4SiW12O40 . nH2O). The conductivity of phosphoric acid doped PBI and PBI composite membranes was found to be dependent on the acid...... doping level, relative humidity (RH) and temperature. A conductivity of 6.8 × 10-2 S cm-1 was observed for PBI membranes with a H3PO4 doping level of 5.6 (mole number of H3PO4 per repeat unit of PBI) at 200°C and 5% RH. A higher conductivity of 9.6 × 10-2 S cm-1 was obtained by blending 15 wt.% of Zr...

  3. Production of activated carbon from peanut hill using phosphoric acid and microwave activation

    Directory of Open Access Journals (Sweden)

    Weerawat Clowutimon

    2015-06-01

    Full Text Available The optimum conditions for preparing activated carbon from peanut hulls by phosphoric acid and microwave activation were studied. Factors investigated in this study were temperature of carbonization at 300, 350, 400 and 450๐ C, and time of carbonization at 30, 60 and 90 minutes. The optimum yield was observed that carbonization temperature of 400๐ C and time at 60 minutes, respectively. The yield of charcoal was 39% and the f ix carbon was 69%. Then the charcoal was activated by phosphoric acid and microwave irradiation, respectively. The effect of the weight per volume ratios of charcoal to activating acid (1:1, 1:2 and 2:1(W/V, microwave power at (activated 300, 500 and 700 watts, and activated time (30, 60 and 90 seconds were studied. The results showed that the optimum conditions for activating peanut charcoal were 1:2 (W/V charcoal per activating acid, microwave power 700 watts for 90 seconds. The results yielding maximum surface area by BET method was 303.1 m2 /g and pore volume was 0.140 cm3 /g. An efficiency of maximum iodine adsorption was 418 mg iodine/g activated carbon. Comparing the adsorption efficiency of non- irradiated and irradiated activated carbon, the efficiency of irradiated activated carbon improved up to 31%, due to its larger surface area and pore volume.

  4. Unexpected 226Ra build-up in wet-process phosphoric-acid plants

    International Nuclear Information System (INIS)

    Lardinoye, M.H.; Weterings, K.; Berg, W.B. van de

    1982-01-01

    During an investigation of the distribution of radium and uranium over the different process streams in phosphoric-acid production and in the nitrophosphate route, a higher than average radiation level was detected in the vicinity of some piping and vessels near the gypsum filters. This higher radiation level is caused by radium which is present in very low concentrations in the phosphates used for fertilizer production. Detectable radiation levels around vessels and piping in other phosphoric-acid works have since been determined. In all factories the filter part and especially the washing-acid section showed the highest radiation level. In the piping of the gypsum filter, through which the washing acid is discharged, a scaling of barium sulphate and calcium sulphate with a higher radium concentration is formed. The radium ions appeared to be incorporated in the barium sulphate lattice, hence the solubility of the radium precipitate is very low. The danger of internal contamination in cleaning operations by radioactive intake or inhalation of radon is very small in the cases described. The risk of external radiation can be prevented by periodically cleaning the equipment in which the radioactive scaling is formed. (author)

  5. Unexpected /sup 226/Ra build-up in wet-process phosphoric-acid plants

    Energy Technology Data Exchange (ETDEWEB)

    Lardinoye, M.H.; Weterings, K. (Stamicarbon B.V., Geleen (Netherlands)); van de Berg, W.B. (Unie van Kunstmestfabrieken, Utrecht (Netherlands))

    1982-04-01

    During an investigation of the distribution of radium and uranium over the different process streams in phosphoric-acid production and in the nitrophosphate route, a higher than average radiation level was detected in the vicinity of some piping and vessels near the gypsum filters. This higher radiation level is caused by radium which is present in very low concentrations in the phosphates used for fertilizer production. Detectable radiation levels around vessels and piping in other phosphoric-acid works have since been determined. In all factories the filter part and especially the washing-acid section showed the highest radiation level. In the piping of the gypsum filter, through which the washing acid is discharged, a scaling of barium sulphate and calcium sulphate with a higher radium concentration is formed. The radium ions appeared to be incorporated in the barium sulphate lattice, hence the solubility of the radium precipitate is very low. The danger of internal contamination in cleaning operations by radioactive intake or inhalation of radon is very small in the cases described. The risk of external radiation can be prevented by periodically cleaning the equipment in which the radioactive scaling is formed.

  6. Unexpected 226Ra build-up in wet-process phosphoric-acid plants.

    Science.gov (United States)

    Lardinoye, M H; Weterings, K; van de Berg, W B

    1982-04-01

    During an investigation of the distribution of radium and uranium over the different process streams in phosphoric-acid production and in the nitrophosphate route, a higher than average radiation level was detected in the vicinity of some piping and vessels near the gypsum filtres. This higher radiation level is caused by radium, which, as a decay product in the 238U series, is present in very low concentrations (1-50 pCi 226R/g) in the phosphates used for fertilizer production. Specific research later on established that there were detectable radiation levels around vessels and piping in other phosphoric-acid works as well. It turned out that in all factories the filter part, and especially the washing-acid section showed the highest radiation-level. In the piping of the gypsum filter, through which the washing acid is discharged, a scaling of bariumsulphate and calciumsulphate with a higher radiumconcentration (+/- 0.1 Ci/g) is formed. The radium ions appeared to be incorporated in the bariumsulphate lattice, hence the solubility of the radium precipitate is very low. The danger of internal pollution, for example in cleaning operations by radio-active intake or inhallation of radon is very small in the cases described. The risk of external radiation can be prevented by periodically cleaning (every 1-3 yr) the equipment in which the radio-active scaling is formed.

  7. Unexpected /sup 226/Ra build-up in wet-process phosphoric-acid plants

    Energy Technology Data Exchange (ETDEWEB)

    Lardinoye, M.H.; Weterings, K.; van de Berg, W.B.

    1982-04-01

    During an investigation of the distribution of radium and uranium over the different process streams in phosphoric-acid production and in the nitrophosphate route, a higher than average radiation level was detected in the vicinity of some piping and vessels near the gypsum filtres. This higher radiation level is caused by radium, which, as a decay product in the /sup 238/U series, is present in very low concentrations (1-50 pCi 226R/g) in the phosphates used for fertilizer production. Specific research later on established that there were detectable radiation levels around vessels and piping in other phosphoric-acid works as well. It turned out that in all factories the filter part, and especially the washing-acid section showed the highest radiation-level. In the piping of the gypsum filter, through which the washing acid is discharged, a scaling of bariumsulfate and calciumsulfate with a higher radium concentration (+/- 0.1 Ci/g) is formed. The radium ions appeared to be incorporated in the bariumsulphate lattice, hence the solubility of the radium precipitate is very low. The danger of internal pollution, for example in cleaning operations by radioactive intake or inhalation of radon is very small in the cases described. The risk of external radiation can be prevented by periodically cleaning (every 1-3 yr) the equipment in which the radioactive scaling is formed.

  8. Improvement of Haramay Fiber by Pre-treatment of Retting Process withPhosphoric Acid

    International Nuclear Information System (INIS)

    Kuntari-Sasas; Neni-Rustini Eriawati

    2000-01-01

    Haramay as bast fiber contains of cellulose fiber as the main part, mixedwith hemi cellulose, pectin, and lignin as binding material for cellulosefiber to keep it together in the bundle form. For textile material, this bastfiber has to be freed from its binding material, called as retting process,before subjecting to scouring, dyeing and finishing process in textileindustry. In the retting process the dissolve of binding material can be doneeither by using enzyme in bio technology or extraction with strong alkalinecondition in common technology. Using sodium hydroxide for dissolving thebinding material can be carried out easily with good dissolving ability, butcan render the strength retention of the cellulose fiber. Pre-treatment ofthe bast fiber with phosphoric acid (H 3 PO 4 ), is expected to hydrolyze someof the binding materials that can not be dissolved in alkaline condition,including natural pigment that colored the fiber with creamy white. In thisstudy, the pre-treatment process before retting with phosphoric acid wascarried out in various condition, such as concentration of phosphoric acid (5ml/l- 25 ml/l), time and temperature of pre-treatment (1-3 hours at 50 o C or12-24 hours at room temperature), followed by neutralization in dilutealkaline. The retting process was carried out by means of scouring in variousconcentration of sodium hydroxide (NaOH 38 o Be, 10 ml/l-30 m/l), and then wascontinued with bleaching process in hydrogen peroxide solution. Aftercarrying out those experiment, the bast fiber that called haramay wassubjected to testing for weight reduction, strength retention and degree ofwhiteness. From the testing results it is concluded that pre-treatment withphosphoric acid can increase the weight reduction, strength retention ortenacity and degree of whiteness of haramay fiber compared to the oneswithout pre-treatment with phosphoric acid. The best result was obtained bypre-treatment with 5 ml/l H 3 PO 4 at 50 o C for 2 hours, continued by

  9. Status of commercial phosphoric acid fuel cell power plant system development

    Science.gov (United States)

    Warshay, M.

    1987-01-01

    A technology development and commercial feasibility evaluation is presented for phosphoric acid fuel cells (PAFCs) applicable to electric utility operations. The correction of identified design deficiencies in the control card and water treatment subsystems is projected to be able to substantially increase average powerplant availability from the 63 percent achieved in recent field tests of a PAFC system. Current development work is proceeding under NASA research contracts at the output levels of a multimegawatt facility for electric utility use, a multikilowatt on-site integrated energy generation facility, and advanced electrocatalysts applicable to PAFCs.

  10. Performance Degradation Tests of Phosphoric Acid Doped PBI Membrane Based High Temperature PEM Fuel Cells

    DEFF Research Database (Denmark)

    Zhou, Fan; Araya, Samuel Simon; Grigoras, Ionela

    2014-01-01

    Degradation tests of two phosphoric acid (PA) doped PBI membrane based HT-PEM fuel cells were reported in this paper to investigate the effects of start/stop and the presence of methanol in the fuel to the performance degradation. Continuous tests with H2 and simulated reformate which was composed...... to the redistribution of PA between the membrane and electrodes. EIS measurement of first fuel cell during the start/stop test showed that the mass transfer resistance and ohmic resistance increased which can be attributed to the corrosion of carbon support in the catalyst layer and degradation of the PBI membrane...

  11. Passivation behaviour of Alloy 31 (UNS N08031) in polluted phosphoric acid at different temperatures

    OpenAIRE

    ESCRIVÁ CERDÁN, CLARA; Blasco Tamarit, María Encarnación; García García, Dionisio Miguel; García Antón, José; Guenbour, A.

    2012-01-01

    The influence of temperature (20–80 °C) and chloride concentration (0.06–0.42 wt.% KCl) on the electrochemical behaviour of the UNS N08031 was studied in 40 wt.% polluted phosphoric acid solution. Passivation behaviour was investigated by using potentiostatic tests at different potentials. From the linear regions of the log i vs. log t transients, the parameter n was obtained. The results showed that the applied potential hardly affects on the passivation rate n. However, n values decreas...

  12. Influence of pH-control in phosphoric acid treatment of titanium oxide and their powder properties

    International Nuclear Information System (INIS)

    Onoda, Hiroaki; Matsukura, Aki

    2015-01-01

    Highlights: • The photocatalytic activity was suppressed by phosphoric acid treatment. • The obtained pigment had small particles with sub-micrometer size. • By phosphoric acid treatment, the smoothness of samples improved. - Abstract: Titanium oxide that has the photocatalytic activity is used as a white pigment for cosmetics. A certain degree of sebum on the skin is decomposed by the ultraviolet radiation in sunlight. In this work, titanium oxide was shaken with phosphoric acid at various pH to synthesize a novel white pigment for cosmetics. Their chemical composition, powder properties, photocatalytic activity, color phase, and smoothness were studied. The obtained materials indicated XRD peaks of titanium oxide, however, these peak intensity became weak by phosphoric acid treatment. These samples without heating and heated at 100 °C included the small particles with sub-micrometer size. The photocatalytic activity of the obtained powders became weak by phosphoric acid treatment at pH 4 and 5 to protect the sebum on the skin

  13. Influence of pH-control in phosphoric acid treatment of titanium oxide and their powder properties

    Energy Technology Data Exchange (ETDEWEB)

    Onoda, Hiroaki, E-mail: onoda@kpu.ac.jp; Matsukura, Aki

    2015-06-15

    Highlights: • The photocatalytic activity was suppressed by phosphoric acid treatment. • The obtained pigment had small particles with sub-micrometer size. • By phosphoric acid treatment, the smoothness of samples improved. - Abstract: Titanium oxide that has the photocatalytic activity is used as a white pigment for cosmetics. A certain degree of sebum on the skin is decomposed by the ultraviolet radiation in sunlight. In this work, titanium oxide was shaken with phosphoric acid at various pH to synthesize a novel white pigment for cosmetics. Their chemical composition, powder properties, photocatalytic activity, color phase, and smoothness were studied. The obtained materials indicated XRD peaks of titanium oxide, however, these peak intensity became weak by phosphoric acid treatment. These samples without heating and heated at 100 °C included the small particles with sub-micrometer size. The photocatalytic activity of the obtained powders became weak by phosphoric acid treatment at pH 4 and 5 to protect the sebum on the skin.

  14. Methyl phosphate formation as a major degradation mode of direct methanol fuel cells with phosphoric acid based electrolytes

    DEFF Research Database (Denmark)

    Aili, David; Vassiliev, Anton; Jensen, Jens Oluf

    2015-01-01

    Phosphoric acid and phosphoric acid doped polymer membranes are widely used as electrolytes in hydrogen based fuel cells operating at elevated temperatures. Such electrolytes have been explored for direct oxidation of methanol to further increase the versatility of the systems, however......, with demonstrated lifetimes of only a few days to weeks. In this work the methyl phosphate formation from the acid and methanol is identified and proposed to be a major mechanism for the cell degradation. Proton conductivity and fuel cell durability tests validate the mechanism at high methanol contents....

  15. Separation of uranium and other metals from commercial phosphoric acid by ion-exchange and voltammetric determination of uranium

    International Nuclear Information System (INIS)

    Ferreira, J.B.C.; Carvalho, F.M.S. de; Abrao, A.

    1985-11-01

    The separation of metals from crude commercial phosphoric acid is achieved by simple dilution and percolation through a strong cationic ion exchanger. Uranium, calcium, magnesium, manganese, iron and aluminum are quantitatively fixed by the exchanger and can be detected or analysed after their complete elution with 6 M HCI. Titanium and zirconium are only partially retained. Specially for its separation and determination uranium is retained selectively by the resin from the phosphoric acid-EDTA solution, the column is washed with water and then eluted with hydrochloric acid. Uranium is analyzed by voltametry with the hanging drop mercury electrode. (Author) [pt

  16. Effect of phosphoric acid etching on the shear bond strength of two self-etch adhesives

    Science.gov (United States)

    SABATINI, Camila

    2013-01-01

    Objective: To evaluate the effect of optional phosphoric acid etching on the shear bond strength (SBS) of two self-etch adhesives to enamel and dentin. Material and Methods: Ninety-six bovine mandibular incisors were ground flat to obtain enamel and dentin substrates. A two-step self-etch adhesive (FL-Bond II) and a one-step self-etch adhesive (BeautiBond) were applied with and without a preliminary acid etching to both the enamel and dentin. The specimens were equally and randomly assigned to 4 groups per substrate (n=12) as follows: FL-Bond II etched; FL-Bond II un-etched; BeautiBond etched; BeautiBond un-etched. Composite cylinders (Filtek Z100) were bonded onto the treated tooth structure. The shear bond strength was evaluated after 24 hours of storage (37ºC, 100% humidity) with a testing machine (Ultra-tester) at a speed of 1 mm/min. The data was analyzed using a two-way ANOVA and post-hoc Tukey's test with a significance level of pself-etch adhesives evaluated while providing improvement on the enamel bond strength only for FL-Bond II. This suggests that the potential benefit that may be derived from an additional etching step with phosphoric acid does not justify the risk of adversely affecting the bond strength to dentin. PMID:23559113

  17. Extraction equilibrium of indium(III) from nitric acid solutions by di(2-ethylhexyl)phosphoric acid dissolved in kerosene.

    Science.gov (United States)

    Tsai, Hung-Sheng; Tsai, Teh-Hua

    2012-01-04

    The extraction equilibrium of indium(III) from a nitric acid solution using di(2-ethylhexyl) phosphoric acid (D2EHPA) as an acidic extractant of organophosphorus compounds dissolved in kerosene was studied. By graphical and numerical analysis, the compositions of indium-D2EHPA complexes in organic phase and stoichiometry of the extraction reaction were examined. Nitric acid solutions with various indium concentrations at 25 °C were used to obtain the equilibrium constant of InR₃ in the organic phase. The experimental results showed that the extraction distribution ratios of indium(III) between the organic phase and the aqueous solution increased when either the pH value of the aqueous solution and/or the concentration of the organic phase extractant increased. Finally, the recovery efficiency of indium(III) in nitric acid was measured.

  18. (Liquid + liquid) equilibria in ternary aqueous mixtures of phosphoric acid with organic solvents at T = 298.2 K

    Energy Technology Data Exchange (ETDEWEB)

    Ghanadzadeh, H., E-mail: hggilani@guilan.ac.i [Department of Chemistry, Faculty of Science, University of Guilan, Rasht (Iran, Islamic Republic of); Department of Chemical Engineering, University of Guilan, Rasht (Iran, Islamic Republic of); Ghanadzadeh, A., E-mail: aggilani@guilan.ac.i [Department of Chemistry, Faculty of Science, University of Guilan, Rasht (Iran, Islamic Republic of); Aghajani, Z.; Abbasnejad, S.; Shekarsaraee, S. [Department of Chemistry, Faculty of Science, University of Guilan, Rasht (Iran, Islamic Republic of)

    2010-06-15

    (Liquid + liquid) equilibrium (LLE) data for the ternary mixtures of left bracewater (1) + phosphoric acid (2) + organic solvents (3)right brace were determined at T = 298.2 K and atmospheric pressure. The organic solvents were cyclohexane, 2-methyl-2-butanol (tert-amyl alcohol), and isobutyl acetate. All the investigated systems exhibit Type-1 behaviour of LLE. The immiscibility region was found to be larger for the (water + phosphoric acid + cyclohexane) ternary system. The experimental LLE results were correlated with the NRTL model, and the binary interaction parameters were obtained. The reliability of the experimental tie-line results was tested through the Othmer-Tobias and Bachman correlation equations. Distribution coefficients and separation factors were evaluated over the immiscibility regions and a comparison of the extracting capabilities of the solvents was made with respect to these factors. The experimental results indicate the superiority of cyclohexane as the preferred solvent for the extraction of phosphoric acid from its aqueous solutions.

  19. (Liquid + liquid) equilibria in ternary aqueous mixtures of phosphoric acid with organic solvents at T = 298.2 K

    International Nuclear Information System (INIS)

    Ghanadzadeh, H.; Ghanadzadeh, A.; Aghajani, Z.; Abbasnejad, S.; Shekarsaraee, S.

    2010-01-01

    (Liquid + liquid) equilibrium (LLE) data for the ternary mixtures of {water (1) + phosphoric acid (2) + organic solvents (3)} were determined at T = 298.2 K and atmospheric pressure. The organic solvents were cyclohexane, 2-methyl-2-butanol (tert-amyl alcohol), and isobutyl acetate. All the investigated systems exhibit Type-1 behaviour of LLE. The immiscibility region was found to be larger for the (water + phosphoric acid + cyclohexane) ternary system. The experimental LLE results were correlated with the NRTL model, and the binary interaction parameters were obtained. The reliability of the experimental tie-line results was tested through the Othmer-Tobias and Bachman correlation equations. Distribution coefficients and separation factors were evaluated over the immiscibility regions and a comparison of the extracting capabilities of the solvents was made with respect to these factors. The experimental results indicate the superiority of cyclohexane as the preferred solvent for the extraction of phosphoric acid from its aqueous solutions.

  20. Catalyst evaluation for oxygen reduction reaction in concentrated phosphoric acid at elevated temperatures

    Science.gov (United States)

    Hu, Yang; Jiang, Yiliang; Jensen, Jens Oluf; Cleemann, Lars N.; Li, Qingfeng

    2018-01-01

    Phosphoric acid is the common electrolyte for high-temperature polymer electrolyte fuel cells (HT-PEMFCs) that have advantages such as enhanced CO tolerance and simplified heat and water management. The currently used rotating disk electrode technique is limited to tests in dilute solutions at low temperatures and hence is not suitable for catalyst evaluation for HT-PEMFCs. In this study, we have designed and constructed a half-cell setup to measure the intrinsic activities of catalysts towards the oxygen reduction reaction (ORR) in conditions close to HT-PEMFC cathodes. By optimization of the hydrophobic characteristics of electrodes and the catalyst layer thickness, ORR activities of typical Pt/C catalysts are successfully measured in concentrated phosphoric acid at temperatures above 100 °C. In terms of mass-specific activities, the catalyst exhibits about two times higher activity in the half-cell electrode than that observed in fuel cells, indicating the feasibility of the technique as well as the potential for further improvement of fuel cell electrode performance.

  1. Optimizing the saccharification of sugar cane bagasse using dilute phosphoric acid followed by fungal cellulases.

    Science.gov (United States)

    Geddes, C C; Peterson, J J; Roslander, C; Zacchi, G; Mullinnix, M T; Shanmugam, K T; Ingram, L O

    2010-03-01

    A low level of phosphoric acid (1% w/w on dry bagasse basis, 160 degrees C and above, 10 min) was shown to effectively hydrolyze the hemicellulose in sugar cane bagasse into monomers with minimal side reactions and to serve as an effective pre-treatment for the enzymatic hydrolysis of cellulose. Up to 45% of the remaining water-insoluble solids (WIS) was digested to sugar monomers by a low concentration of Biocellulase W (0.5 filter paper unit/gWIS) supplemented with beta-glucosidase, although much higher levels of cellulase (100-fold) were required for complete hydrolysis. After neutralization and nutrient addition, phosphoric acid syrups of hemicellulose sugars were fermented by ethanologenic Escherichia coli LY160 without further purification. Fermentation of these syrups was preceded by a lag that increased with increased pre-treatment temperature. Further improvements in organisms and optimization of steam treatments may allow the co-fermentation of sugars derived from hemicellulose and cellulose, eliminating need for liquid-solid separation, sugar purification, and separate fermentations. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

  2. Microabrasion using 18% hydrochloric acid and 37% phosphoric acid in various degrees of fluorosis - an in vivo comparision.

    Science.gov (United States)

    Sinha, Soumya; Vorse, Kiran Kumar; Noorani, Hina; Kumaraswamy, Shivprakash Pujari; Varma, Siddhartha; Surappaneni, Haragopal

    2013-01-01

    The aim of this study was to assess the efficacy of 18% hydrochloric acid and 37% phosphoric acid by an in vivo comparison. Sixty fluorotic permanent maxillary central incisors from 30 patients were divided into 3 categories. The teeth received 5 seconds (mild fluorosis), 20 seconds (moderate fluorosis) and 30 seconds (severe fluorosis) application of 18% hydrochloric acid on 11 and 37% phosphoric acid on 21. Standardized intraoral photographies were taken immediately before, after, and one month after treatment. Vinyl polysiloxane impression of the patient were made before and after the treatment. A scanning electron microscopic (SEM) evaluation was carried out on the models to judge the surface alterations. Wilcoxon and Mann-Whitney tests were used to verify the hypothesis. A statistically significant result was obtained in the reduction of white spot opacities, intensity of stains and the total area occupied by the stains in mild and moderate fluorosis teeth. Results of severe fluorosis had an unpredictable outcome. An SEM evaluation revealed good improvement in the surface texture of mild and moderate fluorosis teeth. Teeth with severe fluorosis showed only a slight improvement. A microabrasion procedure is effective for treating mild and moderate fluorosis cases.

  3. Study of corrosion-erosion behaviour of stainless alloys in industrial phosphoric acid medium

    International Nuclear Information System (INIS)

    Guenbour, Abdellah; Hajji, Mohamed-Adil; Jallouli, El Miloudi; Bachir, Ali Ben

    2006-01-01

    The corrosion and corrosion-abrasion resistance of some stainless steels in industrial phosphoric acid 30% P 2 O 5 has been studied using electrochemical techniques. The corrosion rate of materials increases with the increase of temperature. Alloys which contain chromium, molybdenum and nitrogen in sufficient quantities present the best behaviour. In the abrasion-corrosion conditions, the experimental device set up allowed to follow continually samples electrochemical behaviour. Under dynamic conditions and without solid particles, the increase of acid projection speed has no effect on the alloys corrosion behaviour. The adding of abrasive leads to a general increase of corrosion rate and to a decrease of material resistance. Under these conditions, materials attack is controlled by synergistic effect between the abrasion and the impurities. The cast 30% Cr shows good resistance according to his high chromium content

  4. Purification of Industrial Phosphoric Acid using Silica Produced from Rice Husk (Part 1)

    International Nuclear Information System (INIS)

    Gad, H.M.H.; Awwad, N.S.; El-Khalafawy, A.; Daifullah, A.A.M.; El-Reefy, S.A.; Aly, H.F.

    2008-01-01

    In this work, silica was extracted from rice husk (RH) by different techniques and used for removal of some heavy metals from industrial phosphoric acid. The data obtained, showed that removal of Cu(II), Cd(II) and Pb(II) is efficient when the silica used is obtained by acidic treatment, while the removal of Fe(III) and Zn(II) is efficient when the silica used was obtained by alkaline treatment of RH. On the other hand, if silica used is obtained from rice husk ash (RHA) it was found more efficient for the removal of Mn. In all cases, the concentration of silica has been characterized by UV-Spectrophotometry. FTIR, SEM and EDX were used for predication of sorption mechanism

  5. Ion flotation of uranium contained in industrial phosphoric acid with collector recycling

    International Nuclear Information System (INIS)

    Jdid, E.; Blazy, P.; Bessiere, J.

    1985-01-01

    Uranium has been recovered from wet-process phosphoric acid (30% P 2 O 5 ) by ion flotation with an anionic organophosphorous collector. Recoveries greater than 90% were obtained even at temperatures of about 60 C, the uranium concentrate, which was collected in the froth as a precipitate, containing 7 to 10% U. Collector consumption without recycling of the surface-active reagent was about 12 kg/kg U. Much of the reagent, however, can be recovered for recycling by attack with sodium hydroxide on the floated phase after filtration. This enables a precipitate containing about 30% U to be produced and decreases collector consumption to about 3 kg/kg U. The results were obtained in laboratory-scale experiments on industrial wet-process acid. (author)

  6. Study of the behavior to corrosion of samples of nuclear grade aluminium sheathed in nickel-phosphorous alloys obtained autocatalytically

    International Nuclear Information System (INIS)

    Castro, Maria Eugenia; Barbero, Jose Alfredo; Bubach, Ernesto

    2006-01-01

    One of the ways to protect an industrially important metallic material against corrosion is by covering the piece with an approximately 1 μm layer of a material whose resistance to corrosion is greater than the element being protected. The mechanism by which the anticorrosive protection is obtained is with the formation of a pore free physical barrier without defects that impedes the arrival of the agents responsible for the electrochemical attack. Other sacrifice anodes such as aluminum or zinc have protective forms based on their dissolution as a consequence of their less electrochemically noble behavior to preserve the material. This work studies the resistance to the corrosion of metallic coatings on nuclear grade aluminum substrates. The focus is on coating nickel-phosphorous (ni-P) alloys obtained autocatalytically from aluminum 6061. A comparative study is carried out of a series of electroless nickel coatings containing different amounts of the latter element, but without surpassing the threshold of 12%. The work includes the study of another nickel coating, Vitrovac 0080 (without phosphorous content) in order to compare structures and anticorrosive properties. These materials are also compared with the Al6061 substrate without any kind of coating. The study is carried out with surface characterization of each one of the samples with or without coating using a series of complementary techniques, such as chemical and electrochemical techniques (linear-sweep voltammetry, cyclic voltammetry, determination of the polarization resistance) and physical techniques (SEM microscopy, determination of micro-hardness). The correlation of variables is carried out later as a function of the phosphorous content of the test samples. The structures obtained from the coatings are amorphous. They have no pores or faults and have high hardness values. The electrochemical study proves that the anticorrosive protection capacity of the Ni-P alloy increases along with the

  7. 230Th, 232Th and 238U determinations in phosphoric acid fertilizer and process products by ICP-MS

    International Nuclear Information System (INIS)

    Nascimento, Marcos R.L. do; Guerreiro, Luisa M.R.; Bonifacio, Rodrigo L.; Taddei, Maria H.T.

    2015-01-01

    Through processing of Santa Quiteria-CE mine phosphate rock, Brazil has established a project for production of phosphoric acid fertilizer and uranium as a by-product. Under leaching conditions of phosphate rock with sulfuric acid, which is the common route for preparing phosphoric acid fertilizer, a large part of uranium, thorium and their decay products naturally present in the rock are solubilized. In order to assess the contamination potential in phosphoric acid and others process products, this paper describes a previous precipitation and direct methods for routine analysis of thorium and uranium isotopes by ICP-MS. In all samples, 230 Th, 232 Th and 238 U were directly determined after dilution, except 230 Th in phosphoric acid loaded with uranium sample, which to overcome equipment contamination effect, was determined after its separation by oxalate precipitation using lanthanum as a carrier. The results obtained by the proposed method by ICP-MS, were in good agreement when compared to alpha spectrometry for 230 Th, and ICP-OES and spectrophotometry with arsenazo III for elementary uranium and thorium determinations. (author)

  8. The Process of Acetonitrile Synthesis over γ-Al2O3 Promoted by Phosphoric Acid Catalysts

    OpenAIRE

    Galanov, Sergey I.; Sidorova, Olga I.; Gavrilenko, Mikhail A.

    2014-01-01

    The influence of principal parameters (reaction temperature, ratio of acetic acid and ammonia, composition of reactionary mixture and promotion of catalysts) on the selectivity and yield of the desired product was studied in the reaction of catalytic acetonitrile synthesis by ammonolysis of acetic acid. The processing of [gamma]-Al[2]O[3] by phosphoric acid increases amount of the centers, on which carries out reaction of acetamide dehydration. The kinetic model of a limiting stage of reactio...

  9. Efficacy of sodium hypochlorite, ethylenediaminetetraacetic acid, citric acid and phosphoric acid in calcium hydroxide removal from the root canal: a microscopic cleanliness evaluation.

    Science.gov (United States)

    da Silva, Juliana Melo; Silveira, Amanda; Santos, Elizandra; Prado, Laiìs; Pessoa, Oscar F

    2011-12-01

    Rooted molars were subjected to standardized canal instrumentation to a master apical file (MAF). The samples were dressed with Ca(OH)(2), and after 7 days, teeth were reopened and Ca(OH)(2) medication was removed by 1 of 4 different experimental procedures: 2.5% sodium hypochlorite (NaOCl) (n = 10); 17% EDTA-T (n = 10); 10% citric acid (n = 10); or 37% phosphoric acid (n = 10). This was followed by reinstrumentation with MAF plus 15 mL saline solution. The roots were prepared for scanning electron microscopic analysis of the cervical, middle, and apical thirds. Statistical analysis was performed with the Kruskal-Wallis test. EDTA-T and phosphoric acid gave the best results in the apical third, with significant statistical differences compared with other groups. NaOCl gave the worst results. Irrigation with 17% EDTA-T and 37% phosphoric acid is more effective than sodium hypochlorite and citric acid in the removal of calcium hydroxide from the apical third. Copyright © 2011 Mosby, Inc. All rights reserved.

  10. Towards a desalination initiative using cogeneration with an advanced reactor type and uranium recovered from Moroccan phosphoric acid production

    International Nuclear Information System (INIS)

    Lung, M.; Kossir, A.; Msatef, D.

    2005-01-01

    Morocco is known to be among the first few countries to produce phosphate and phosphoric acid. Moroccan phosphate contains substantial amounts of uranium. This uranium can be recovered from the phosphate ore as a by-product during the production of phosphoric acid. Uranium extraction processes linked with phosphoric acid fabrication have been used industrially in some countries. This is done mainly by solvent extraction. Although, the present price of uranium is low in the international market, such uranium recovery could be considered as a side product of phosphoric acid production. The price of uranium has a very small impact on the cost of nuclear energy obtained from it. This paper focuses on the extraction of uranium salt from phosphate rock. If uranium is recovered in Morocco in the proposed manner, it could serve as feed for a number of nuclear power plants. The natural uranium product would have to be either enriched or blended as mixed-oxide fuel to manufacture adequate nuclear fuel. Part of this fuel would feed a desalination initiative using a high temperature reactor of the new generation, chosen for its intrinsic safety, sturdiness, ease of maintenance, thermodynamic characteristics and long fuel life between reloads, that is, good economy. An international cooperation based on commercial contract schemes would concern: the general project and uranium extraction; uranium enrichment and fuel fabrication services; the nuclear power plant; and the desalination plant. This paper presents the overall feasibility of the general project with some quantitative preliminary figures and cost estimates. (author)

  11. Temperature dependence and P/Ti ratio in phosphoric acid treatment of titanium dioxide and powder properties.

    Science.gov (United States)

    Onoda, H; Matsukura, A

    2015-02-01

    Titanium dioxide has photocatalytic activity and is used as a white pigment for cosmetics. A certain degree of sebum on the skin is decomposed by the ultraviolet radiation in sunlight. In this work, titanium dioxide was shaken with phosphoric acid to synthesize a white pigment for cosmetics. Titanium dioxide was treated with 0.1 mol/L of phosphoric acid at various P/Ti molar ratios, and then shaken in hot water for 1 h. The chemical composition, powder properties, photocatalytic activity, colour phase, and smoothness of the obtained powder were studied. The obtained materials indicated XRD peaks of titanium dioxide, however the peaks diminished subsequent to phosphoric acid treatment. The samples included small particles with sub-micrometer size. The photocatalytic activity of the obtained powders decreased, decomposing less sebum on the skin. Samples prepared at high P/Ti ratio with high shaking temperature indicated low whiteness in in L*a*b* colour space. The shaking and heating temperature and P/Ti ratio had influence on the smoothness of the obtained materials. Phosphoric acid treatment of titanium dioxide is an effective method to inhibit photocatalytic activity for a white pigment. © 2014 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

  12. Palladium-Catalyzed Enantioselective C-H Activation of Aliphatic Amines Using Chiral Anionic BINOL-Phosphoric Acid Ligands.

    Science.gov (United States)

    Smalley, Adam P; Cuthbertson, James D; Gaunt, Matthew J

    2017-02-01

    The design of an enantioselective Pd(II)-catalyzed C-H amination reaction is described. The use of a chiral BINOL phosphoric acid ligand enables the conversion of readily available amines into synthetically valuable aziridines in high enantiomeric ratios. The aziridines can be derivatized to afford a range of chiral amine building blocks incorporating motifs readily encountered in pharmaceutically relevant molecules.

  13. Study of a Triazole Derivative as Corrosion Inhibitor for Mild Steel in Phosphoric Acid Solution

    Directory of Open Access Journals (Sweden)

    Lin Wang

    2012-01-01

    Full Text Available The corrosion inhibition by a triazole derivative (PAMT on mild steel in phosphoric acid (H3PO4 solution has been investigated by weight loss and polarization methods. The experimental results reveal that the compound has a significant inhibiting effect on the corrosion of steel in H3PO4 solution. It also shows good corrosion inhibition at higher concentration of H3PO4. Potentiodynamic polarization studies have shown that the compound acts as a mixed-type inhibitor retarding the anodic and cathodic corrosion reactions with predominant effect on the cathodic reaction. The values of inhibition efficiency obtained from weight loss and polarization measurements are in good agreement. The adsorption of this compound is found to obey the Langmuir adsorption isotherm. Some kinetic and thermodynamic parameters such as apparent activation energy, frequency factor, and adsorption free energy have been calculated and discussed.

  14. Effect of Phosphoric Acid Concentration on the Optical Properties of Partially Phosphorylated PVA Complexes

    Directory of Open Access Journals (Sweden)

    Asmalina Mohamed Saat

    2014-01-01

    Full Text Available Partially phosphorylated polyvinyl alcohol (PPVA films were prepared at five mole ratios of phosphoric acid (PA using solution casting technique. The optical properties of the PPVA films were examined using UV-visible (UV and photoluminescence (PL spectroscopy. The UV absorption spectra reveal that the absorption peaks are blue-shifted with an increase in PA concentration added to the pure PVA. The PL spectra show the presence of peaks which are characteristic of isotactic (389–398, 460–462 nm, syndiotactic (418–420 nm, and atactic (440–446 nm configurations of the PPVA. The results also show the peak of O–P–O bonding at a wavelength range of 481–489 nm.

  15. Synthesis of the mono- and di(4-(1,1,3,3-tetramethylbutyl)) phosphoric acids

    International Nuclear Information System (INIS)

    Elias, H.; Zaoui, A.; Attou, M.; Hadj Bachir, D.; Bouzidi, N.; Didi, M.

    1995-09-01

    This work is related to the synthesis of organophosphorus extracting agents used in purification of heavy metals such as uranium. The mono- and di (4-(1,1,3,3- tetramethylbutyl)) phenyl phosphoric acids, respectively MOPPA and DOPPA, are synthesizd by reaction of phosphorus pentoxid with 4(1,1,3,3-tetramethylbuthyl)) phenol. the separation of MOPPA from DOPPA is realised by liquid-liquid extraction. The Characterization, carried out by infrared uv-visible spectrophotometries, ph-metry and mass spectrometry, has confirmed the identity of the synthesized products. This study also showed that the products proportions are comporable to those of the homologous products obtained with 2-ethylbexanol in the same synthesis conditions

  16. Trial operation of a phosphoric acid fuel cell (PC25) for CHP applications in Europe

    Energy Technology Data Exchange (ETDEWEB)

    Uhrig, M.; Droste, W.; Wolf, D. [Ruhrgas AG, Dorsten (Germany)

    1996-12-31

    In Europe, ten 200 kW phosphoric acid fuel cells (PAFCs) produced by ONSI (PC25) are currently in operation. Their operators collaborate closely in the European Fuel Cell Users Group (EFCUG). The experience gained from trial operation by the four German operators - HEAG, HGW/HEW, Thyssengas and Ruhrgas - coincides with that of the other European operators. This experience can generally be regarded as favourable. With a view to using fuel cells in combined heat and power generation (CHP), the project described in this report, which was carried out in cooperation with the municipal utility of Bochum and Gasunie of the Netherlands, aimed at gaining experience with the PC 25 in field operation under the specific operating conditions prevailing in Europe. The work packages included heat-controlled operation, examination of plant behavior with varying gas properties and measurement of emissions under dynamic load conditions. The project received EU funding under the JOULE programme.

  17. Assessment and comparison of 100-MW coal gasification phosphoric acid fuel cell power plants

    Science.gov (United States)

    Lu, Cheng-Yi

    1988-01-01

    One of the advantages of fuel cell (FC) power plants is fuel versatility. With changes only in the fuel processor, the power plant will be able to accept a variety of fuels. This study was performed to design process diagrams, evaluate performance, and to estimate cost of 100 MW coal gasifier (CG)/phosphoric acid fuel cell (PAFC) power plant systems utilizing coal, which is the largest single potential source of alternate hydrocarbon liquids and gases in the United States, as the fuel. Results of this study will identify the most promising integrated CG/PAFC design and its near-optimal operating conditions. The comparison is based on the performance and cost of electricity which is calculated under consistent financial assumptions.

  18. 3,3'-Diaryl-BINOL phosphoric acids as enantioselective extractants of benzylic primary amines.

    Science.gov (United States)

    Verkuijl, Bastiaan J V; de Vries, Johannes G; Feringa, Ben L

    2011-01-01

    We report that 3,3'-diaryl-BINOL phosphoric acids are effective enantioselective extractants in chiral separation methods based on reactive liquid-liquid extraction. These new extractants are capable of separating racemic benzylic primary amine substrates. The effect of the nature of the substituents at the 3,3'-positions of the host were examined as well as the structure of the substrate, together with important parameters such as the organic solvent, the pH of the aqueous phase, and the host stoichiometry. Titration of the substrate with the host was monitored by FTIR, NMR, UV-Vis, and CD spectroscopy, which provided insight into the structure of the host-guest complex involved in extraction. Copyright © 2010 Wiley-Liss, Inc.

  19. Analysis and evaluation of the possibility of introducing phosphoric acid fuel cells

    Science.gov (United States)

    1991-03-01

    Each step in the manufacture of fuel cells is reviewed. The possibility of cost reduction in the process is investigated. Additionally, the feasibility of providing financial assistance for fuel cell buyers is investigated. Also, the present status and the future outlook of fuel cell development are discussed. In Japan, phosphoric acid fuel cells are beginning demonstration testing. A 200 kW test plant, for commercial and remote island use, has finished its demonstration test favorably. The test run of an 11 mW plant, for the production of electric power, is being conducted by a private company. The manufacture of each of the fuel cell's subsystems is semi-automated at this time. The costs are estimated to be reduced to 60 - 80 percent of the present costs in a 10 mW/year plant and TO 50 - 60 percent of the present costs in a 100 mW/year plant.

  20. A contribution to the study of thorium and neptunium (IV) complexes in acidic phosphoric media

    International Nuclear Information System (INIS)

    Ghafar, M.

    1995-01-01

    The thorium and neptunium (IV) phosphate complexes formation in acidic media has been investigated, essentially at the indicator's level with 227 Th, 234 Th, 235 Np and 239 Np. Solvent extraction, a commonly used method for determining stability constants in solutions, was used with HDEHP in toluene. In order to get a better understanding of inorganic transparent gels formation in phosphoric aqueous solutions, the effect of the thorium concentration is also studied. Specific experimental conditions have been chosen in order to avoid the formation of chelate and hydrolysis in the aqueous solution. The equilibrium constants and stability constants are calculated, and the results are compared with literature. The results show that increasing the thorium concentration does not lead to polymer forms. refs., 42 figs., 19 tabs

  1. Fructo-oligosaccharide production from inulin through partial citric or phosphoric acid hydrolyses.

    Science.gov (United States)

    Fontana, José Domingos; Grzybowski, Adelia; Tiboni, Marcela; Passos, Maurício

    2011-11-01

    Purified inulin from Dahlia tubers was partially hydrolyzed to form fructo-oligosaccharides by using citric or phosphoric acids (pH, 2.0-2.5) as mild acid catalysts. The ideal kinetic conditions to ensure a high yield of fructo-oligosaccharides relative to free fructose were a temperature range of 85°C-95°C, a hydrolysis time of 15-25 minutes, and a catalyst pH of 2.5. At the higher temperature and the longest hydrolysis time, an inversion of the product ratio occurred. Under these conditions, co-generation of hydroxymethylfurfural occurred, and it was eliminated by activated charcoal. Unlike in classic hydrolysis with hydrochloric or sulfuric acid, deionization of the actual hydrolysates was not necessary because the catalyst neutralization with common bases results in the formation of co-nutrients with alternative uses as foods or fermentation substrates. These whole hydrolysates can be advantageously added as nutraceuticals to carbonated beverages and acidic foods, such as soft drinks and yogurts.

  2. Physicochemical properties of phosphoric acid doped polybenzimidazole membranes for fuel cells

    DEFF Research Database (Denmark)

    He, Ronghuan; Li, Qingfeng; Bach, Anders

    2006-01-01

    Polybenzimidazole (PBI) membranes have been prepared with different molecular weights. The water and acid swelling, mechanical strength,gas permeability and proton conductivity were studied for the pristine and acid doped PBI membranes. When doped with 5 mol of phosphoric acid per mole repeat unit...... of the polymer, a level necessary to obtain high enough proton conductivity for fuel cell uses, the polymer membrane exhibits a volume swelling by 118%, resulting in separation of the polymer backbones. The separation in turn reduces the mechanical strength of the membrane especially at high temperatures....... Another consequence is the increased H2 and O2 permeability through the membrane. In the temperature range from 120 to 180 ◦C, the hydrogen permeability was found to be 1.6–4.3×10−17 and 1.2–4.0×10−15 mol cm cm−2 s−1 Pa−1 for pristine and acid doped PBI membranes, respectively, while for oxygen it was 5...

  3. Microleakage of Sealants after Phosphoric Acid, Er: YAG Laser and Air Abrasion Enamel Conditioning: Systematic Review and Meta-Analysis.

    Science.gov (United States)

    Fumes, Ana Caroline; Longo, Daniele Lucca; De Rossi, Andiara; Fidalgo, Tatiana Kelly da Silva; de Paula E Silva, Francisco Wanderley Garcia; Borsatto, Maria Cristina; Küchler, Erika Calvano

    The aim of this systematic review and meta-analysis is to answer the focused question: Does the application of phosphoric acid, Er:YAG laser and air abrasion enamel conditioning methods previous to the oclusal sealant application in human permanent molars influence the microleakage? A literature research was carried out in the Pubmed Medline, Web of Science, Scopus and Cochrane databases using with the MeSH terms and keyword search strategy. A supplemental hand search of the references of retrieved articles was also performed. Inclusion criteria comprised ex vivo studies (extracted teeth) with permanent human teeth that used chemical (phosphoric acid) or mechanical (Er:YAG laser and air abrasion) conditioning methods previous the sealant application. The studies should evaluate microleakage as an outcome. Meta-analysis pooled plot were obtained comparing the microleakage after pre-treatment with phosphoric acid, Er:YAG and air abrasion enamel conditioning for sealant application using RevMan software. The search resulted in 164 articles, 55 records were excluded because they were duplicated. The analysis of titles and abstracts resulted in the exclusion of 105 studies. Four studies were included in the systematic review and the meta-analysis. According to the risk of bias evaluation, the four studies were considered low risk of bias. The meta-analysis showed that phosphoric acid had lower microleakage than Er:YAG laser (p air abrasion (p laser and air abrasion (p > 0.05). The evidence supports that the pretreatment with phosphoric acid leads lower microleakage in oclusal sealants than Er:YAG laser and air abrasion.

  4. Surface modification of Y3Al5O12:Ce3+ phosphor by hydrofluoric acid wet etching

    International Nuclear Information System (INIS)

    He, Zhijiang; Cheng, Weihai; Li, Zebin; Liu, Ying; Ou, Qiongrong; Liang, Rongqing

    2013-01-01

    The surface of Y 3 Al 5 O 12 :Ce 3+ phosphor prepared by solid-state reaction was modified by hydrofluoric acid wet etching. The SEM pictures show that the edge-angles-rich surface of the phosphor particles becomes smooth and the XRD spectra show that the surface crystallinity is improved after modification for more than 3 h. Consequently, the photoluminescence emission from phosphor particles with smooth surface presents a higher quantum yield (increased by 5.5%) than that without modification, and a lower backscattering light by the smoothed phosphor particles is also found, which suggests better surface characteristics of light absorption, transparency and crystallinity. -- Highlights: ► HF wet etching way is introduced to modify the YAG phosphor surface for the first time. ► The surface with riched edge angles has become smooth. ► The photoluminescence emission intensity is increased by 5.5%. ► The backscattering light intensity is obviously decreased. ► The wet etching method with HF is appropriate for mass process

  5. The solvent extraction of terbium and europium by di-(2-ethylhexyl)-phosphoric acid and various organophosphorous compounds

    International Nuclear Information System (INIS)

    Kandil, A.T.; Farah, K.

    1980-01-01

    The extraction of Tb 3+ and Eu 3+ by di-(2-ethylhexyl)-phosphoric acid, HDEHP in seven different solvents from an aqueous phase of 0.1 M ionic strength is studied as a function of the pH and the acid concentration. Antagonistic effects are observed when the extraction was studied by mixtures of HDEHP and tributylphosphate, TBP, or trioctylphosphine oxide (TOPO). (author)

  6. Oxygen Reduction on Gas-Diffusion Electrodes for Phosphoric Acid Fuel Cells by a Potential Decay Method

    DEFF Research Database (Denmark)

    Li, Qingfeng; Gang, Xiao; Hjuler, Hans Aage

    1995-01-01

    The reduction of gaseous oxygen on carbon supported platinum electrodes has been studied at 150 degrees C with polarization and potential decay measurements. The electrolyte was either 100 weight percent phosphoric acid or that acid with a fluorinated additive, potassium perfluorohexanesulfonate (C...... and the dependence of the double-layer capacitance on the overpotential depended on the electrode manufacture and the kind of electrolyte (whether containing the fluorinated additive or not)....

  7. In-situ polymerized polyaniline films. Preparation in solutions of hydrochloric, sulfuric, or phosphoric acid

    International Nuclear Information System (INIS)

    Sedenkova, Ivana; Trchova, Miroslava; Blinova, Natalia V.; Stejskal, Jaroslav

    2006-01-01

    Polyaniline (PANI) was prepared by the oxidative polymerization of aniline hydrochloride and aniline sulfate with ammonium peroxydisulfate in acidic aqueous medium. Aniline was similarly oxidized in solution of phosphoric acid. Thin PANI films are produced at the interfaces with the reaction mixture. The progress of polymerization and the PANI-film formation were monitored in situ by Fourier transform infrared spectroscopy after depositing a droplet of the reaction mixture on a ZnSe crystal. The influences of chloride, sulfate, and phosphate counter-ions on the initiation and progress of aniline polymerization have been analysed. The spectra of the completed PANI films protonated with various acids have been compared with the spectra of the corresponding PANI bases obtained after deprotonating the films with ammonium hydroxide. The peaks in the region 3400-2800 cm -1 , so-called H-peaks, have been analyzed in detail. The influence of chloride, sulfate, and phosphate counter-ions on the shape and position of some of the peaks has been noted

  8. Phosphoric acid distribution in the membrane electrode assembly of high temperature proton exchange membrane fuel cells

    International Nuclear Information System (INIS)

    Kwon, Kyungjung; Park, Jung Ock; Yoo, Duck Young; Yi, Jung S.

    2009-01-01

    The ionomer content in electrode is one of the most important parameters for the high performance of fuel cells. The high temperature PEMFC based on phosphoric acid (PA)-doped polymer membrane with unhumidified reactant gases has a difficulty in controlling the liquid state PA ionomer content in electrode. To evaluate the PA content in electrode, the three techniques of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and acid-base titration (ABT) are carried out in situ or ex situ. The properties of membrane electrode assembly (MEA) such as electrochemical surface area (ESA), ohmic resistance, charge transfer resistance, double layer capacitance and the amount of PA in MEA components (anode, cathode and membrane) are extracted by each technique. Ex situ CV with the usage of dry gases has a limitation in assessing the reliable ESA of unhumidified PEMFC. While in situ EIS presents some informative values of resistance and capacitance for understanding the PA distribution in MEA, its sensitivity to the PA content in MEA components needs to be higher for detecting a subtle change in PA distribution. Ex situ ABT supplies a clear PA distribution in MEA at room temperature but does not seem to reflect the operating state well at high temperatures. However, it can be used as a detection tool for the loss of the initial acid content in membrane during a long-term MEA durability study.

  9. Physicochemical properties of carbons prepared from pecan shell by phosphoric acid activation.

    Science.gov (United States)

    Guo, Yanping; Rockstraw, David A

    2007-05-01

    Activated carbons were prepared from pecan shell by phosphoric acid activation. The pore structure and acidic surface groups of these carbons were characterized by nitrogen adsorption, Boehm titration and transmittance Fourier infrared spectroscopy (FTIR) techniques. The characterization results demonstrated that the development of pore structure was apparent at temperatures 250 degrees C, and reached 1130m(2)/g and 0.34cm(3)/g, respectively, at 500 degrees C. Impregnation ratio and soaking time at activation temperature also affected the pore development and pore size distribution of final carbon products. At an impregnation ratio of 1.5, activated carbon with BET surface area and micropore volume as high as 861m(2)/g and 0.289cm(3)/g was obtained at 400 degrees C. Microporous activated carbons were obtained in this study. Low impregnation ratio (less than 1.5) and activation temperature (less than 300 degrees C) are favorable to the formation of acidic surface functional groups, which consist of temperature-sensitive (unstable at high temperature) and temperature-insensitive (stable at high temperature) two parts. The disappearance of temperature-sensitive groups was significant at temperature 300 degrees C; while the temperature-insensitive groups are stable even at 500 degrees C. FTIR results showed that the temperature-insensitive part was mostly phosphorus-containing groups as well as some carbonyl-containing groups, while carbonyl-containing groups were the main contributor of temperature-sensitive part.

  10. Search for a developed method for the determination of Fe2 and Fe3 in Syrian Phosphoric acid

    International Nuclear Information System (INIS)

    Elian, Nuzhat; Kalak, Issam

    1988-08-01

    Phosphoric acid is the most important precursor for uranium production in Syria. Uranium extraction from phosphoric acid depends on the chemical composition of the acid, and most important is the relation between the proportions of iron I I/iron I II, and uranium I V/uranium V I, this proportion plays a very important role in different steps of the extraction. For this purposes two methods for determination of Iron I I and Iron I II in Syrian wet phosphoric acid spectrophotometrically were studied. The first one used 1.10 phenanthroline as complex agent. Iron I I formed red complex with 1.10 phenonstholine in the range of pH between 4 and 6, for determination of total iron. Iron I II was reduced to Iron I I with hydroxylamine hydrochloride. The second method used sulfosalycilic acid, Iron I II formed a yellow complex with sulfosalycilic acid. Total iron was determined in ammonium medium, but Iron I II was determined in pH=1.5. The sensibility of the tow methods and stability of their complex have been studied in normal laboratory conditions. 45 refs., 4 figs. (author)

  11. Direct uranium extraction from dihydrate and hemi-dihydrate wet process phosphoric acids by liquid emulsion membrane

    International Nuclear Information System (INIS)

    El-Hazek, N.T.; El Sayed, M.S.

    2003-01-01

    A new liquid emulsion membrane (LEM) process for uranium extraction from either dihydrate 28-30% P 2 O 5 (DH) or hemi-dihydrate 42-45% P 2 O 5 (HDH) wet process phosphoric acid is proposed. In this process, the organic component of the LEM is composed of a synergistic mixture of 0.1M di-2-ethyl hexyl phosphoric acid (DEHPA) and 0.025M trioctyl phosphine oxide (TOPO) with 4% Span 80. The internal or the strip acid phase is composed of 0.5M citric acid. The prepared LEM was proved to be stable in 42-45% P 2 O 5 acid concentration range and can, therefore, be applied to the phosphoric acid produced by the hemi-dihydrate process. After breakdown of the loaded emulsion, the uranyl citrate in the internal strip phase is separated by adding methanol followed by its calcination to the orange oxide. Most of the reagents used are recycled. The proposed process is characterized by simplicity, practically closed operation cycle in addition to lower capital and operating costs. (author)

  12. Extraction behavior of U(IV) from nitric acid medium using di-isodecyl phosphoric acid dissolved in dodecane

    International Nuclear Information System (INIS)

    Sujoy Biswas; Hareendran, K.N.; Roy, S.B.; Singh, D.K.; Sharma, J.N.

    2010-01-01

    Solvent extraction of U(VI) with di-isodecyl phosphoric acid (DIDPA)/dodecane from nitric acid medium has been investigated for a wide range of experimental conditions. Effect of various parameters including nitric acid concentration, DIDPA concentration, temperature, stripping agents, and other impurities like rear earths, transition metal ion, boron, aluminum ion on U(VI) extraction has been studied. The species extracted in the organic phase is found to be UO 2 (NO 3 )(HA 2 ) · H 2 A 2 at lower acidity ( 3 ). Increase in temperature lead to the decrease in extraction with the enthalpy change by ΔH = -16.27 kJ/mol. Enhancement in extraction of U(VI) from nitric acid medium was observed with the mixture of DIDPA and tri butyl phosphate (TBP). The stripping of U(VI) from organic phase (DIDPA-U(VI)/dodecane) with various reagents followed the order: 4 M H 2 SO 4 > 5% (NH 4 ) 2 CO 3 > 8 M HCl > 8 M HNO 3 > Water. High separation factors between U(VI) and impurities suggested that the use of DIDPA for purification of uranium from multi elements bearing solution. (author)

  13. Determination of sulfate in the wet-process of phosphoric acid by reverse flow injection

    Directory of Open Access Journals (Sweden)

    Wenhui Shi

    2014-01-01

    Full Text Available An improved method based on reverse flow injection is proposed for determining sulfate concentration in the wet-process of phosphoric acid (WPA. The effect of reagent composition, flow rate, temperature, acid concentration, length of the reaction coil, and linear response range on the flow system is discussed in detail. Optimal conditions are established for determining sulfate in the WPA samples. Baseline drift is avoided by a periodic washing step with EDTA in an alkaline medium. A linear response is observed within a range of 20 - 360 mg L-1, given by the equation A = 0.0020C (mg L-1 + 0.0300, R² = 0.9991. The detection limit of the proposed method for sulfate analysis is 3 mg L-1, and the relative standard deviation (n = 12 of sulfate absorbance peak is less than 1.60%. This method has a rate of up to 29 samples per hour, and the results compare well with those obtained with gravimetric method.

  14. Thermal properties of phosphoric acid-doped polybenzimidazole membranes in water and methanol-water mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Nores-Pondal, Federico J.; Corti, Horacio R. [Grupo de Pilas de Combustible, Departamento de Fisica de la Materia Condensada, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica (CNEA), Av. General Paz 1499, B1650KNA San Martin, Buenos Aires (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (Argentina); Buera, M. Pilar [Consejo Nacional de Investigaciones Cientificas y Tecnicas (Argentina); Departamento de Industrias, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Av. Cantilo s/n, Ciudad Universitaria (1428) Buenos Aires (Argentina)

    2010-10-01

    The thermal properties of phosphoric acid-doped poly[2-2'-(m-phenylene)-5-5' bi-benzimidazole] (PBI) and poly[2,5-benzimidazole] (ABPBI) membranes, ionomeric materials with promising properties to be used as electrolytes in direct methanol and in high temperature polymer electrolyte membrane (PEM) fuel cells, were studied by means of differential scanning calorimetry (DSC) technique in the temperature range from -145 C to 200 C. The DSC scans of samples equilibrated in water at different relative humidities (RH) and in liquid water-methanol mixtures were analyzed in relation to glass transition, water crystallization/melting and solvent desorption in different temperature regions. The thermal relaxation observed in the very low temperature region could be ascribed to the glass transition of the H{sub 3}PO{sub 4}-H{sub 2}O mixture confined in the polymeric matrix. After cooling the samples up to -145 C, frozen water was detected in PBI and ABPBI at different RH, although at 100% RH less amount of water had crystallized than that observed in Nafion membranes under the same conditions. Even more important is the fact that the freezing degree of water is much lower in ABPBI membranes equilibrated in liquid water-methanol mixtures than that observed for PBI and, in a previous study, for Nafion. Thus, apart from other well known properties, acid-doped ABPBI emerges as an excellent ionomer for applications in direct methanol fuel cells working in cold environments. (author)

  15. Treatment alternatives of liquid radioactive waste containing uranium in phosphoric acid

    International Nuclear Information System (INIS)

    Bustamante Escobedo, Mauricio

    2003-01-01

    The UGDR, receives annually 100 [l] of liquid radioactive waste containing, highly acid (pH=0) uranium in phosphoric acid from the Laboratory of Chemical Analysis. This waste must be chemically and radiologically decontaminated before it can be discharged in accordance with local environmental standards. Chemical precipitation and evaporation test were carried out to define the operating conditions for the radiological decontamination of this radioactive waste and to obtain a solid waste that can be conditioned in a cement matrix. The evaporation process generates excellent rates of volume reduction, over 80%, but generates a pulp that is hard handle when submitted to a drying process. Chemical precipitation generates good results for decontaminating these solutions and reducing volume (above 50%) to obtain a uranium free effluent. The treatment with calcium carbonate generated an effluent with a low concentration of polluting agents. A preliminary test was carried out condition these solids in a cement matrix, using ratios of 0.45 waste/cement and 2 of water/cement. The mix prepared with waste from the sodium hydroxide treatment had low mechanical resistance resulting from the saline incrustations. The waste from the calcium carbonate treatment was very porous due to the water evaporation from the highly exothermic reaction between the waste and the cement. The mix of the calcium carbonate generated waste and the cement matrix needs to be optimized, since it generates favorable conditions for adhering with the cement matrix (au)

  16. A Novel Method for Fabricating Double Layers Porous Anodic Alumina in Phosphoric/Oxalic Acid Solution and Oxalic Acid Solution

    Directory of Open Access Journals (Sweden)

    Yanfang Xu

    2016-01-01

    Full Text Available A novel method for fabricating ordered double layers porous anodic alumina (DL-PAA with controllable nanopore size was presented. Highly ordered large pore layer with interpore distance of 480 nm was fabricated in phosphoric acid solution with oxalic acid addition at the potential of 195 V and the small pore layer was fabricated in oxalic acid solution at the potential from 60 to 100 V. Experimental results show that the thickness of large pore layer is linearly correlative with anodizing time, and pore diameter is linearly correlative with pore widening time. When the anodizing potential in oxalic acid solution was adjusted from 60 to 100 V, the small pore layers with continuously tunable interpore distance from 142 to 241 nm and pore density from 1.94×109 to 4.89×109 cm−2 were obtained. And the interpore distance and the pore density of small pore layers are closely correlative with the anodizing potential. The fabricated DL-PAA templates can be widely utilized for fabrication of ordered nanomaterials, such as superhydrophobic or gecko-inspired adhesive materials and metal or semiconductor nanowires.

  17. Immobilization of Zn, Cu, and Pb in contaminated soils using phosphate rock and phosphoric acid

    Energy Technology Data Exchange (ETDEWEB)

    Cao Xinde [School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)] [Soil and Water Science Department, University of Florida, Gainesville, FL 32611 (United States); Wahbi, Ammar [Soil Science Department, Faculty of Agriculture, University of Aleppo, Aleppo (Syrian Arab Republic); Ma, Lena, E-mail: lqma@ufl.edu [Soil and Water Science Department, University of Florida, Gainesville, FL 32611 (United States); Li Bing; Yang Yongliang [National Research Center for Geoanalysis, Beijing 100037 (China)

    2009-05-30

    Considerable research has been done on P-induced Pb immobilization in Pb-contaminated soils. However, application of P to soils contaminated with multiple heavy metals is limited. The present study examined effectiveness of phosphoric acid (PA) and/or phosphate rock (PR) in immobilizing Pb, Cu, and Zn in two contaminated soils. The effectiveness was evaluated using water extraction, plant uptake, and a simple bioaccessibility extraction test (SBET) mimicking metal uptake in the acidic environment of human stomach. The possible mechanisms for metal immobilization were elucidated using X-ray diffraction, scanning electron microscopy, and chemical speciation program Visual MINTEQ. Compared to the control, all P amendments significantly reduced Pb water solubility, phytoavailability, and bioaccessibility by 72-100%, 15-86%, and 28-92%, respectively. The Pb immobilization was probably attributed to the formation of insoluble Pb phosphate minerals. Phosphorus significantly reduced Cu and Zn water solubility by 31-80% and 40-69%, respectively, presumably due to their sorption on minerals (e.g., calcite and phosphate phases) following CaO addition. However, P had little effect on the Cu and Zn phytoavailability; while the acid extractability of Cu and Zn induced by SBET (pH 2) were even elevated by up to 48% and 40%, respectively, in the H{sub 3}PO{sub 4} treatments (PA and PR + PA). Our results indicate that phosphate was effective in reducing Pb availability in terms of water solubility, bioaccessibility, and phytoavailability. Caution should be exercised when H{sub 3}PO{sub 4} was amended to the soil co-contaminated with Cu and Zn since the acidic condition of SBET increased Cu and Zn bioaccessibility though their water solubility was reduced.

  18. Studies on the solvent extraction behaviour of Pu(IV) from nitric acid, nitric-perchloric acid and hydrochloric acids, by di,2-ethylhexyl phosphoric acid (HDEHP)

    International Nuclear Information System (INIS)

    Phal, D.G.; Kannan, S.K.; Ramakrishna, V.V.

    1994-01-01

    Extraction of plutonium (IV) from aqueous nitric acid, nitric-perchloric acid and hydrochloric acids by di,2-ethylhexyl phosphoric acid, the dimeric form of which is represented as H 2 Y 2 , in different diluents (dodecane, toluene and chloroform) was investigated. The composition of the extracted Pu(IV) species were found to be Pu(NO 3 ) 2 (HY) 2 , Pu(NO 3 )(ClO 4 )(HY 2 ) 2 , PuClY(HY 2 ) 2 and PuCl 2 (HY 2 ) 2 from nitric, nitric-perchloric and hydrochloric acids respectively, the last one being pre-dominant at high aqueous acidities (i.e. 5M HCl). Synergic enhancement in the extraction of Pu(IV) from different aqueous media, by the addition of thenoyltrifluoroacetone (HTTA) to HDEHP was also investigated and was attributed to the formation and extraction of the species PuX(TTA)(HY 2 ) 2 , and Pu(TTA) 2 (HY 2 ) 2 where X=Cl - or NO 3 - . The addition of the neutral extractant TOPO to H 2 Y 2 also resulted in synergism. The possible equilibria in these systems were inferred and the corresponding equilibrium constants determined. (author). 24 refs., 10 figs., 10 tabs

  19. Passivation behaviour of stainless steel (UNS N-08028) in industrial or simplified phosphoric acid solutions at different temperatures

    International Nuclear Information System (INIS)

    Ben Salah, M.; Sabot, R.; Refait, Ph.; Liascukiene, I.; Méthivier, C.; Landoulsi, J.; Dhouibi, L.

    2015-01-01

    Highlights: • Industrial phosphoric acid is less aggressive than simulated industrial acid. • Polyphosphate film in Industrial acid is reinforced by calcium and sulfate. • Passive film thickness is obtained by the power law model from EIS measurements. • Passive film of Sanicro28 becomes more resistive towards corrosion with exposure time in industrial acid. • XPS measurements coupled to Raman spectroscopy reveal the corrosion products formed in simulated acid. - Abstract: The corrosion behaviour of Sanicro28, in industrial phosphoric acid and simplified solution of pure H 3 PO 4 containing sulphates and chlorides, is investigated during 48 h between 20 and 80 °C. Results show higher corrosion resistance in the industrial medium. Film thickness evaluated by EIS remains constant in industrial acid due to polyphosphate that promotes crystallisation of the Cr 2 O 3 inner layer. Conversely, the passive film is partially destroyed at 80 °C in simplified acid. XPS and Raman analysis show that phosphate and molybdenum are both present in the passive film and in corrosion products. The role of Ca present in the industrial acid is discussed.

  20. Stabilisation of heavy metal containing dusts by reaction with phosphoric acid: study of the reactivity of fly ash

    International Nuclear Information System (INIS)

    Bournonville, Blandine; Nzihou, Ange; Sharrock, Patrick; Depelsenaire, Guy

    2004-01-01

    Water-washed fly ash was reacted with phosphoric acid in order to transform available heavy metals into insoluble metal phosphate compounds. The temperature, pH and concentration of free phosphate were monitored during the first 80 min of reaction. Phosphoric acid reacted rapidly with second order kinetics and an apparent rate constant of 0.015 l/(mol s m 2 ). Analysis of the evolution of the concentrations of other major elements of fly ash shows that the reaction follows a dissolution-precipitation type mechanism. The solubility of trace heavy metals tends to increase at low pH values. Various heat and mass transfer coefficients are derived and help understand the phosphate stabilisation procedure and design industrial reactors for this purpose. Calcium phosphates are formed which can trap heavy metals in a stable apatite mineral structure

  1. Performance Degradation Tests of Phosphoric Acid Doped Polybenzimidazole Membrane Based High Temperature Polymer Electrolyte Membrane Fuel Cells

    DEFF Research Database (Denmark)

    Zhou, Fan; Araya, Samuel Simon; Grigoras, Ionela

    2015-01-01

    Degradation tests of two phosphoric acid (PA) doped PBI membrane based HT-PEM fuel cells were reported in this paper to investigate the effects of start/stop and the presence of methanol in the fuel to the performance degradation of the HT-PEM fuel cell. Continuous tests with pure dry H2 and meth......Degradation tests of two phosphoric acid (PA) doped PBI membrane based HT-PEM fuel cells were reported in this paper to investigate the effects of start/stop and the presence of methanol in the fuel to the performance degradation of the HT-PEM fuel cell. Continuous tests with pure dry H2...... to the corrosion of carbon support in the catalyst layer and degradation of the PBI membrane. During the continuous test with methanol containing H2 as the fuel the reaction kinetic resistance and mass transfer resistance of both single cells increased, which may be caused by the adsorption of methanol...

  2. Organic-inorganic interaction between hydroxyapatite and gelatin with the aging of gelatin in aqueous phosphoric acid solution.

    Science.gov (United States)

    Chang, Myung Chul

    2008-11-01

    Hydroxyapatite (HAp)/gelatin (GEL) nanocomposite was prepared by the solution-precipitation process using Ca(OH)(2) in water and aqueous solution of H(3)PO(4) in GEL. Before the co precipitation process the GEL powders were dissolved in the aqueous phosphoric acid solution for the phosphorylation of GEL molecules. The chemical variation of the phosphorylated GEL macromolecules was investigated by using attenuated total reflection (ATR) measurement. The crystal growth of HAp became bigger with the long-time aging of the GEL molecules in the phosphoric acid solution, and it resulted from the reduction of length scale of the GEL molecules. The degree of the organic-inorganic interaction was decreased because of the degradation of the GEL macromolecules.

  3. Multistage dilute acid leaching of a medium grade iron ore to super-concentrate

    Directory of Open Access Journals (Sweden)

    Adeleke A.A.

    2014-01-01

    Full Text Available The phosphorous laden Koton Karfe iron ore is a medium grade iron ore deposit in Nigeria that can be upgraded as a super-concentrate for use at the Aladja Steel Midrex plant. The 75 μm size sample fraction of the ore was preconcentrated with shaking table and leached in the oven at atmospheric pressure with dilute hydrochloric acid in single and multistage leaching sequences of H2O-HCl-H2O and HCl-H2O-H2O. The as-received, as-tabled and asleached samples were then subjected to X-ray fluorescence and microscopic analyses. The results obtained showed that the H2O-HCl-H2O route produced a higher grade concentrate that assayed 68.54% Fe indicating about 58% upgrade in iron content; while the phosphorus and sulphur contents were reduced by about 77 and 99.6% respectively. In addition, the silicon, manganese, and titanium contents were drastically reduced, while potassium was completely eliminated. The upgrade of iron content in the ore to 68.54% and the drastic reduction in phosphorous and sulphur contents has thus rendered the Koton Karfe iron ore suitable for use as a super concentrate for the Aladja steel plant direct reduction iron making process.

  4. Microhardness, Structure, and Morphology of Primary Enamel after Phosphoric Acid, Self-Etching Adhesive, and Er:YAG Laser Etching

    Directory of Open Access Journals (Sweden)

    María del Carmen Zoila Alcantara-Galeana

    2017-01-01

    Full Text Available Background. Phosphoric acid is the traditional etching agent; self-etching adhesives and Er:YAG laser are alternative methods. Knowledge of deciduous enamel etching is required. Aim. To evaluate primary enamel microhardness, structure, and morphology after phosphoric acid, self-etching, and Er:YAG laser etching. Design. Seventy primary incisors were assigned to five groups (n=14: I (control, II (35% phosphoric acid, III (self-etching adhesive, IV (Er:YAG laser at 15 J/cm2, and V (Er:YAG laser at 19.1 J/cm2. Microhardness was evaluated by Vickers indentation. Chemical composition was analyzed by energy dispersive X-ray spectroscopy and morphological changes by scanning electron microscopy. One-way ANOVA, Kruskal–Wallis, Mann–Whitney U, and Pearson bivariate correlation were employed (α=0.05. Results. Vickers microhardness showed differences and no correlation with Ca/P ratio. Group II showed differences in carbon, oxygen, and phosphorus atomic percent and group V in Ca/P ratio. Morphological changes included exposed prisms, fractures, craters, and fusion. Conclusions. Enamel treated with phosphoric acid showed different chemical characterization among groups. Self-etching and Er:YAG laser irradiation at 19.1 J/cm2 showed similar microhardness and chemical characterization. Er:YAG laser irradiation at 15 J/cm2 maintained microhardness as untreated enamel. Er:YAG laser irradiation at 19.1 J/cm2 enhanced mineral content. Morphological retentive changes were specific to each type of etching protocol.

  5. Temperature Effect on the Austenitic Stainless Steel UNS N08031 Used in the Wet Method Phosphoric Acid Production

    OpenAIRE

    ESCRIVÁ CERDÁN, CLARA; Blasco Tamarit, María Encarnación; García García, Dionisio Miguel; García Antón, José; Guenbour, Abdellah

    2013-01-01

    The influence of temperature (between 20 and 80 degrees C) on the electrochemical behaviour of UNS N08031 (Alloy 31) was evaluated in a contaminated phosphoric acid solution, which simulates the typical concentrations used in the industrial wet process (40 wt.% H3PO4, 2 wt.% H2SO4 and 0.42 wt.% KCl). Alloy 31 electrochemical behaviour was studied by means of polarisation curves and electrochemical impedance spectroscopy. Results demonstrated that temperature decreases the corrosion resistance...

  6. Laser enhanced reductions of uranium(VI) ion in aqueous phosphoric acid solutions

    International Nuclear Information System (INIS)

    Park, Y.Y.; Harada, M.; Tomiyasu, H.; Ikeda, Y.; Takashima, Y.

    1991-01-01

    Photochemical reactions of U(VI) ions with inorganic anions (I - , Br - , Cl - , NCS - ) and organic compounds (1-hexene, cyclohexene, pyridine) in phosphoric acid were studied for the purpose of finding an efficient method of adjusting the oxidation states of uranium ions in nuclear fuel reprocessing. The formation of U(IV) was observed in the photoreactions with I - , Br - and NCS - , but not with Cl - . The yield of U(VI) increased in the order, Br - - - . This order was the same as the quenching rate constants of the excited U(VI) ions with these anions, and the reverse of their standard redox potentials. The rates of the formation of U(IV) in the presence of Br - were measured spectrophotometrically. It was found that the rate equation was first order in both [U(VI)] and [Br - ]. The results were reasonably interpreted by a series of reaction processes involving U(V) and Br radical. With organic molecules, 1-hexene, cyclohexene, and pyridine, the formation of U(IV) were observed. The yield of U(IV) increased in the order pyridine < 1-hexene < cyclohexene. This order is the reverse of their vertical ionization potentials, suggesting an electron transfer mechanism between these organic molecules and excited U(VI). (author)

  7. Effect of aluminum anodizing in phosphoric acid electrolyte on adhesion strength and thermal performance

    Science.gov (United States)

    Lee, Sulki; Kim, Donghyun; Kim, Yonghwan; Jung, Uoochang; Chung, Wonsub

    2016-01-01

    This study examined the adhesive bond strength and thermal performance of the anodized aluminum 6061 in phosphoric acid electrolyte to improve the adhesive bond strength and thermal performance for use in metal core printed circuit boards (MCPCB). The electrolyte temperature and applied voltage were altered to generate varied pore structures. The thickness, porosity and pore diameter of the anodized layer were measured. The pore morphologies were affected most by temperature, which was the driving force for ion transportation. The mechanism of adhesive bond was penetration of the epoxy into the pores. The optimal anodization conditions for maximum adhesive bond strength, 27 MPa, were 293 K and 100V. The maximum thermal conductivity of the epoxy-treated anodized layer was 1.6 W/m·K at 273 K. Compared with the epoxy-treated Al layer used for conventional MCPCBs, the epoxy-treated anodized layer showed advanced thermal performance due to a low difference of thermal resistance and high heat dissipation.

  8. Development of ternary alloy cathode catalysts for phosphoric acid fuel cells: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Jalan, V.; Kosek, J.; Giner, J.; Taylor, E. J.; Anderson, E.; Bianchi, V.; Brooks, C.; Cahill, K.; Cropley, C.; Desai, M.; Frost, D.; Morriseau, B.; Paul, B.; Poirier, J.; Rousseau, M.; Swette, L.; Waterhouse, R.

    1988-11-01

    The overall objective of the program was the identification development and incorporation of high activity platinum ternary alloys on corrosion resistant supports, for use in advanced phosphoric acid fuel cells. Two high activity ternary alloys, Pr-Cr-Ce and Pt-Ni-Co, both supported on Vulcan XC-72, were identified during the course of the program. The Pr-Ni-Co system was selected for optimization, including preparation and evaluation on corrosion resistant supports such as 2700/degree/C heat-treated Vulcan XC-72 and 2700/degree/ heat-treated Black Pearls 2000. A series of tests identified optimum metal ratios, heat-treatment temperatures and heat-treatment atmospheres for the Pr-Ni-Co system. During characterization testing, it was discovered that approximately 50% of the nickel and cobalt present in the starting material could be removed, subsequent to alloy formation, without degrading performance. Extremely stable full cell performance was observed for the Pt-Ni-Co system during a 10,000 hour atmosphere pressure life test. Several theories are proposed to explain the enhancement in activity due to alloy formation. Recommendations are made for future research in this area. 62 refs., 23 figs., 27 tabs.

  9. Removal of chromium(VI) from wastewater using phosphoric acid treated activated carbon

    Science.gov (United States)

    Suganthi, N.

    2013-06-01

    Activated carbon prepared by phosphoric acid treatment of tamarind nuts (seeds) was investigated for the removal of Cr(VI) from aqueous solutions. The characteristics of phosphorylated tamarind nut carbon (PTNC) were evaluated for porosity and surface area. The effect of contact time, pH, adsorbent dose and particle size variation were studied to evaluate the potential applicability of carbon for treating Cr(VI) containing wastewater. The adsorbent data were modeled by Langmiur and Freundlich classical adsorption isotherms. The kinetic studies showed that Cr(VI) adsorption on PTNC was in compliance with the pseudo-second-order kinetic model. Desorption studies indicated that ion-exchange mechanism was operating. The continuous adsorption was studied in glass columns of 2.5 cm diameter using electroplating wastewater to ascertain the practical applicability of PTNC in large scale. The mechanism of adsorption was found to be ion-exchange process and was supported by FTIR spectroscopy. The surface modification after adsorption was confirmed by SEM studies.

  10. Investigation Regarding the Operation of Absorption Refrigerator using Waste Heat of Phosphoric acid Fuel Cell

    Science.gov (United States)

    Kimijima, Shinji; Waragai, Shisei; Uekusa, Tsuneo; Kawai, Sunao

    Fuel cells are emerging as a major power generation system that is suitable for distributed power generation from a view point of high efficiency and low pollutant emission, In order to develop high efficiency system, it is indispensable to take into consideration effective use of waste heat recovered from power generation unit. And the system design that is based on the characteristics of individual component and all of the system is significant. In this report, characteristics of phosphoric acid fuel cell (PAFC) cogeneration system, especially waste heat recovery from PAFC cell stack and exhaust gas is discussed, and operation of absorption refrigerator using waste heat of PAFC are investigated. PAFC cogeneration test facility is constructed, power generation and waste heat recovery experiment is carried out, and system performance is evaluated, As a result, beneficial knowledge are obtained as follows: It is clarified that the cell stack waste heat is dominant for the exhaust gas heat recovery characteristics, and the cooling performance of absorption refrigerator in partial load operation of PAFC. And, the effect of cooling water temperature on the performance of waste heat recovery and absorption refrigerator is obtained.

  11. Erection of a Stainless-Steel Tank for Storing a Phosphoric Acid

    Directory of Open Access Journals (Sweden)

    Vojvodič Tuma, J.

    2007-01-01

    Full Text Available A storage tank for 93 % phosphoric acid was built in Luka Koper from 7 mm thick ground hot-rolled plates of 316L stainless steel. The capacity of the storage tank is of the 750 m3, diameter of 11 m and the height of 8,2 m. The shell plates were welded manually using the shielded metal-arc and gas-metal-arc processes. Before the erection, welding procedure tests according to EN 288-3 were carried out. During the construction several non-destructive examination methods were used, such as radiographic testing and visual and liquid penetrant examination. After the entire tank and roof structure were completed, a hydrostatic leak test was carried out. The surfaces of all the welds on the internal surface of the vessel were ground and the roughness was checked on site. The surfaces of the base material and the ground welds were passivated and tested for resistance to corrosion with electrochemical measurements.

  12. Study of oxidation-reduction reactions of plutonium and neptunium in sulphuric-phosphoric acid media

    International Nuclear Information System (INIS)

    Moiseev, I.V.; Kuperman, A.Ya.; Borodina, N.N.; Galkina, V.N.; Vinokurov, V.A.

    1976-01-01

    Potentiostatic, coulometric, potentiometric, and amperometric methods have been used for determining the rate constants of disproportionation (ksub(d)) of plutonium(5) and neptunium (5) and normal real redox potentials (Esub(0)sup(p)) of the following ion pairs in sulphur-phosphoric-acid media: PuOsub(2)sup(2)sup(+) (PuO 2 + , Pu 4+ /Pu 3+ , NpO 2 2+ /NpO 2 + , NpO 2 2+ /Np 4+ , NpO 2 + /Np 4+ , and Fe 3+ /Fe 2+ . The regularities have been shown of changing ksub(d) and Esub(o)sup(p) as a function of H 2 SO 4 and H 3 PO 4 concentration. It has been established that for plutonium and neptunium a linear correlation is observed between lg ksub(d) and Esub(o)sup(p) of the ion pairs NpO 2 2+ /NpO 2 + , NpO 2 2 /Np 4+ , NpO 2 + /Np 4+ and PuO 2 2+ /PuO 2 + in a wide range of their values. The correlation coefficient is close to unity in all cases (no less than 0.96). The results of investigations have made it possible to recommend optimum compositions of background electrolytes for performing continuous amperostatic coulometric titration of Pusup((6)) and Npsup((6)) up to four valent state by electrogenerated ions of iron (2)

  13. Conversion of spent solid phosphoric Acid catalyst to environmentally friendly fertilizer.

    Science.gov (United States)

    Merwe, Werner van der

    2010-03-01

    Solid phosphoric acid (SPA) catalysts are widely used in the petroleum industry. Despite a high phosphorus content the spent catalyst is generally not reused. Moreover, due to the limited life spans that are achieved industrially, large quantities of spent catalyst requires disposal, often by landfill. SPA can be readily converted to fertilizer, but the presence of carbonaceous deposits on the catalyst presents a potential environmental hazard. This work demonstrates that these deposits are mostly polyaromatic (amorphous carbon) with smaller amounts of oxygenates and aliphatics. Neither the chemical makeup nor the physical structure of the catalyst or the presence of coke precludes it from use as fertilizer. Subsequently, the spent catalyst was milled, neutralized with lime and ammonium hydroxide, and then calcined to yield a phosphate-rich fertilizer. Toxicity characteristic leaching tests of the spent catalyst fertilizer showed low levels of metals and organics, establishing that no harmful compounds are likely to be absorbed into plant life or groundwater. A plant growth study of the spent catalyst fertilizer indicated that it is approximately as effective as superphosphate fertilizer when used in alkaline soil. The spent catalyst fertilizer is environmentally benign and economically efficient.

  14. Preparation and Characterization of Various Activated Carbons Derived From Mixed Precursors Using Phosphoric Acid

    International Nuclear Information System (INIS)

    Daifullah, A.A.M.; Sharaf El-Deen, S.E.A.; Elkhalafawy, A.; Shehata, F.A.; Mahmoud, W.H.

    2008-01-01

    Rice straw (RS) and rice husk (RH), a low-cost agricultural by-products, have been used as a mixed precursor (i.e., RS mixed with RH in 1:1; 1:3 and 3:1 ratios) for the production of novel carbons using phosphoric acid as chemical activation. The raw materials were impregnated with 50% and 70% H 3 PO 4 followed by activation at 500 degree C. The latter proved to be the most effective in producing active carbon with good adsorptive capacity. The resulting carbons were characterized by elemental analysis, infrared spectroscopy, density, SEM and S BET . In general, the resulting carbons showed reasonable surface areas with mainly micropore structure. The adsorption capacity was demonstrated by the isotherms of methylene blue (MB), phenol and iodine from aqueous solution. The adsorption data was found to conform with the Langmuir equation with the concentration range studied, and the monolayer coverage was determined for each of the samples. It was found that surface area is mainly attributed to micropore volume so that phenol adsorption and iodine number correspond well with surface area determined by nitrogen adsorption

  15. Recovery of uranium from wet process phosphoric acid by solvent extraction

    International Nuclear Information System (INIS)

    Hurst, F.J.

    1976-01-01

    The OPPA process offers three potential advantages over the DEPA-TOPO process. The OPPA extractant is much less expensive and has a higher extraction power for uranium than the DEPA-TOPO solvent. In addition it extracts U(IV), the prevailing oxidation state of uranium in wet-process phosphoric acid and this eliminates the liquor oxidation step required in the DEPA-TOPO process. However, the DEPA-TOPO solvent is known to be extremely stable and this process has been successfully demonstrated on a pilot-plant scale at phosphate plants. It is understood that several companies are planning to commercialize this process in the near future. On the other hand, the potentially more attractive OPPA process has not been proven in a pilot plant operation and some questions about the solubility and stability of the OPPA need to be answered. Because of the wide spread interest in this process, a program was started in cooperation with Mobil and Allied Chemical companies to study this extractant, to identify and isolate the material that solubilizes the mono- and diacids, and to determine the optimum concentration and ratios for uranium extraction. In addition, a long-term cyclic test is planned to better define solubility losses and stability of the extractant. Consideration will also be given to improving the recovery of uranium lost to the gypsum during calcination. 12 figures

  16. Solvent Extraction of Rare Earths by Di-2 Ethylhexyl Phosphoric Acid

    International Nuclear Information System (INIS)

    Srinuttrakul, Wannee; Kranlert, Kannika; Kraikaew, Jarunee; Pongpansook, Surasak; Chayavadhanangkur, Chavalek; Kranlert, Kannika

    2004-10-01

    Solvent extraction has been widely applied for individual rare earth separation because the separation time is rapid and a large quantity of products is obtained. In this work, this technique was utilized to extract mixed rare earths, obtained from monazite digestion process. Di-2-ethylhexyl phosphoric acid (D2EHPA) was used as an extractant. The factors affected the extraction including HNO 3 concentration in mixed rare earth nitrate solution and the amount of D2EHPA were studied. The appropriate concentrations of HNO 3 and D2EHPA were found to be 0.01 and 1.5 M, respectively. From the result of equilibrium curve study, it was observed that heavy rare earths were extracted more efficient than light rare earths. A 6-stage continuous countercurrent solvent extraction was simulated for rare earth extraction. The optimum ratio of solvent to feed solution (S/F) was 2. Because of the high cost of D2EHPA, 1.0 M of D2EHPA was suitable for the rare earth extraction by the continuous countercurrent solvent extraction

  17. Computational Characterization of the Origin of Selectivity in Cycloaddition Reactions Catalyzed by Phosphoric Acid Derivatives.

    Science.gov (United States)

    Liu, Chunhui; Besora, Maria; Maseras, Feliu

    2016-02-04

    The mechanism of the organocatalyzed [4+2] cycloaddition of ο-hydroxybenzaldimines to 2,3-dihydro-2 H-furan (DHF) to form furanobenzopyrans has been investigated by using computational methods. Experiments have shown that this reaction produces different products (trans-fused or cis-fused) if different phosphoric acid derivatives are applied. Our study shows the reaction proceeds through a mechanism in which the imine re-arranges into an amine, which subsequently reacts with DHF with mediation from the catalyst. The rate-limiting step in this process is the formation of two new bonds, which is also the key step in determining the reaction selectivity. The selectivity is controlled by a balance of noncovalent interactions between the catalyst and the substrates. The discriminating factor between the two catalysts is the presence of a triflyl substituent on one of catalysts, which constraints the relative orientations of the substrates. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Wet process of phosphoric acid purification by solvent extraction using tri-n-butyl phosphate and cyclohexanol mixtures

    Directory of Open Access Journals (Sweden)

    Li Xing

    2017-01-01

    Full Text Available Solvent extraction is an efficient, economical and widely-used technology for the purification of wet process phosphoric acid (WPA. This present work focused on the development of a solvent extraction system, TC, representing tri-n-butyl phosphate (TBP and cyclohexanol mixtures. The equilibrium phase diagram of the system H3PO4−H2O−TC at 298.2 K and atmospheric pressure was obtained. The effects of extraction time, phosphoric acid concentration, extractant concentration, temperature and phase volume ratio on extraction efficiency were studied. The extracted complexes were estimated to be 1.8H3PO4 2TC. The extraction process of H3PO4 was exothermic and the enthalpy change, ΔH, was obtained. The solvent mixtures had a high efficiency for phosphoric acid purification via multi-stage counter-current extraction from the industrial WPA in a reciprocating plate extraction column with an H3PO4 extraction yield of 85.08 % at 313.2 K. The stability, extraction efficiency and recycling capability of TC for H3PO4 extraction were also estimated.

  19. Extraction of cellulose nano-crystals from old corrugated container fiber using phosphoric acid and enzymatic hydrolysis followed by sonication.

    Science.gov (United States)

    Tang, Yanjun; Shen, Xiaochuang; Zhang, Junhua; Guo, Daliang; Kong, Fangong; Zhang, Nan

    2015-07-10

    Due to its amazing physicochemical properties and high environmental compatibility, cellulose nano-crystals (CNC) hold great promise for serving as a strategic platform for sustainable development. Now, there has been growing interest in the development of processes using waste or residual biomass as CNC source for addressing economic and environmental concerns. In the present work, a combined process involving phosphoric acid hydrolysis, enzymatic hydrolysis and sonication was proposed aiming to efficiently exact CNC from low-cost old corrugated container (OCC) pulp fiber. The effect of enzymatic hydrolysis on the yield and microstructure of resulting CNC was highlighted. Results showed that the enzymatic hydrolysis was effective in enhancing CNC yield after phosphoric acid hydrolysis. CNC was obtained with a yield of 23.98 wt% via the combined process with phosphoric acid concentration of 60 wt%, cellulase dosage of 2 mL (84 EGU) per 2g fiber and sonication intensity of 200 W. Moreover, the presence of enzymatic hydrolysis imparted the obtained CNC with improved dispersion, increased crystallinity and thermal stability. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Dentin matrix components extracted with phosphoric acid enhance cell proliferation and mineralization.

    Science.gov (United States)

    Salehi, Satin; Cooper, Paul; Smith, Anthony; Ferracane, Jack

    2016-03-01

    Acids, such as those used in adhesive dentistry, have been shown to solubilize bioactive molecules from dentin. These dentin matrix components (DMC) may promote cell proliferation and differentiation, and ultimately contribute to dentin regeneration. The objective of this study was to evaluate the potential for varying concentrations of DMC extracted from human dentin by phosphoric acid of a range of pHs to stimulate proliferation and mineralization of two different cultured pulp cell populations. DMC were solubilized from powdered human dentin (7 days - 4°C) by phosphoric acid of pH 1, 3, and 5 and also, EDTA. Extracts were dialyzed for 7 days against distilled water and lyophilized. Undifferentiated mouse dental pulp cells (OD-21) and cells of the odontoblast-like cell line (MDPC-23) were seeded in six-well plates (1×10(5)) and cultured for 24h in DMEM (Dulbecco's modified Eagle's medium) containing 10% (v/v) FBS (fetal bovine serum). The cells were washed with serum-free medium and then treated with different concentrations of DMC (0.01, 0.1, 1.0 and 10.0μg/ml) daily in serum free medium for 7 days. After 3, 5 (MDPC-23 only), and 7 days of treatment, cell proliferation was measured using 10vol% Alamar blue solution, which was added to each well for 1h. Cell numbers were first measured by cell counting (Trypan blue; n=5) and Alamar blue fluorescence to validate the assay, which was then used for the subsequent assessments of proliferation. Mineralization was assessed by Alizarin Red S assay after 12 days exposure to DMC (n=5). Controls were media-only (DMEM) and dexamethasone (DEX; positive control). Results were analysed by ANOVA/Tukey's (p≤0.05). There was a linear correlation between cell counts and Alamar blue fluorescence (R(2)>0.96 for both cell types) , verifying the validity of the Alamar blue assay for these cell types. In general, there was a dose-dependent trend for enhanced cell proliferation with higher concentration of DMC for both cell lines

  1. Comparison of enamel bond fatigue durability between universal adhesives and two-step self-etch adhesives: Effect of phosphoric acid pre-etching.

    Science.gov (United States)

    Suda, Shunichi; Tsujimoto, Akimasa; Barkmeier, Wayne W; Nojiri, Kie; Nagura, Yuko; Takamizawa, Toshiki; Latta, Mark A; Miyazaki, Masashi

    2017-11-23

    The effect of phosphoric acid pre-etching on enamel bond fatigue durability of universal adhesives and two-step self-etch adhesives was investigated. Four universal adhesives and three two-step self-etch adhesives were used. The initial shear bond strengths and shear fatigue strengths to enamel with and without phosphoric acid pre-etching using the adhesives were determined. SEM observations were also conducted. Phosphoric acid pre-etching of enamel was found to increase the bond fatigue durability of universal adhesives, but its effect on two-step self-etch adhesives was material-dependent. In addition, some universal adhesives with phosphoric acid preetching showed similar bond fatigue durability to the two-step self-etch adhesives, although the bond fatigue durability of universal adhesives in self-etch mode was lower than that of the two-step self-etch adhesives. Phosphoric acid pre-etching enhances enamel bond fatigue durability of universal adhesives, but the effect of phosphoric acid pre-etching on the bond fatigue durability of two-step self-etch adhesives was material-dependent.

  2. Study of the properties of dialkyl thiophosphoric acids. Application to the extraction of U, in phosphoric and nitric solutions

    International Nuclear Information System (INIS)

    Benjelloun, N.

    1983-09-01

    A study is made of complex formation and liquid-liquid extraction of uranium (VI) by dialkyl-thiophosphoric acids of formula (RO) 2 POSH and by the synergic mixtures: dialkylthiophosphoric acids-phosphine oxides. The aqueous phases studied consist of concentrated phosphoric acid solutions and nitric acid solutions. Several methods, including distribution coefficient measurements, U.V., visible and infrared absorption spectrophotometries and magnetic resonance, were used to study the extraction mechanisms and the structures of species formed in the organic phase. The influence of different parameters (partition of extraction agent, dimerisation, acid ligand-phosphine oxide association, extraction of inorganic acids...) on the uranium (VI) distribution coefficients enabled the constants of complex formation in the aqueous phase and extraction in the organic phase to be determined. These various properties were compared with those of dialkyl phosphoric and dithiophosphoric acids. The mechanisms established prove that sulfur donors ligands form stable complexes with UO 2 2+ ions although U(VI) is considered as a ''hard class a'' acceptor according to Ahrland's classification [fr

  3. Effect of Phosphoric Acid Concentration on the Characteristics of Sugarcane Bagasse Activated Carbon

    Science.gov (United States)

    Adib, M. R. M.; Suraya, W. M. S. W.; Rafidah, H.; Amirza, A. R. M.; Attahirah, M. H. M. N.; Hani, M. S. N. Q.; Adnan, M. S.

    2016-07-01

    Impregnation method is one of the crucial steps involved in producing activated carbon using chemical activation process. Chemicals employed in this step is effective at decomposing the structure of material and forming micropores that helps in adsorption of contaminants. This paper explains thorough procedures that have been involved in producing sugarcane bagasse activated carbon (SBAC) by using 5%, 10%, 20%, 30% phosphoric acid (H3PO4) during the impregnation step. Concentration of H3PO4 used in the process of producing SBAC was optimized through several tests including bulk density, ash content, iodine adsorption and pore size diameter and the charactesristic of optimum SBAC produced has been compared with commercial activated carbon (CAC). Batch study has been carried out by using the SBAC produced from optimum condition to investigate the performance of SBAC in removal of turbidity and chemical oxygen demand (COD) from textile wastewater. From characteristic study, SBAC with 30% H3PO4 has shown the optimum value of bulk density, ash content, iodine adsorption and pore size diameter of 0.3023 g cm-3, 4.35%, 974.96 mg/g and 0.21-0.41 µm, respectively. These values are comparable to the characteristics of CAC. Experimental result from the batch study has been concluded that the SBAC has a promising potential in removing turbidity and COD of 75.5% and 66.3%, respectively which was a slightly lower than CAC which were able to remove 82.8% of turbidity and 70% of COD. As a conclusion, the SBAC is comparable with CAC in terms of their characteristics and the capability of removing contaminants from textile wastewater. Therefore, it has a commercial value to be used as an alternative of low-cost material in producing CAC.

  4. 1000kW phosphoric acid fuel cell power plant. Outline of the plant

    Energy Technology Data Exchange (ETDEWEB)

    Shinobe, Kenji; Suzuki, Kazuo; Kaneko, Hideo

    1988-02-10

    The outline of the 1000KW phosphoric acid fuel cell power plant, developed as part of the Moonlight plan, was described. The plant was composed of 4 stacks of 260KW DC output. They were devided into two train with 680V and 765A. The generation efficiency of the plant was 40% and more. Steam reforming of natural gas was used. As the fuel, fuel cell exhaust gas was used in composition with the natural gas. The DC-AC inverter had an efficiency of 96%. The capacity of hot water generator and demineralized water plant for cell cooling were 2t/h and 1.6t/h, respectively, and air-system was incorporated. In September of 1987, the plant has succeeded in 1000KW power generation, and put in operation now. Under the 100% loaded condition, each cell had a voltage of 0.7V with little variation, and the current was 200mA/cm/sup 2/. No problems were found in cooling conditions and in the control of interpole differential pressure. The reformer has been operated for 1200h scince its commisioning, and had experiences of 100 times on start up-shut down operations, the reformer also indicated good performances in the gas compositions. The starting time of 8h and the load follow-up rate 10%/min remain as the subjects for shortening. DC-AC conversion was good. The concentration of NOx and the noise level satisfied the target values. (12 figs, 1 tab)

  5. Characterization of phosphogypsum wastes associated with phosphoric acid and fertilizers production.

    Science.gov (United States)

    El Afifi, E M; Hilal, M A; Attallah, M F; El-Reefy, S A

    2009-05-01

    The present work is directed to characterize the phosphogypsum (PG) wastes associated with phosphoric acid produced by the wet process in industrial facility for the production of fertilizers and chemicals in Egypt. The PG waste samples were characterized in terms of spectroscopic analysis (X-ray diffraction, X-ray fluorescence, IR spectra) and radiometric analysis (gamma- and alpha-measurements). The gamma-ray measurements showed that the average activity concentrations are 140+/-12.6, 459+/-36.7, 323+/-28.4, 8.3+/-0.76 and 64.3+/-4.1 Bq/kg for U-238, Ra-226, Pb-210, Th-232 and K-40, respectively. The alpha-particle measurements of uranium isotopes showed that the average activity concentrations of U-238, U-235 and U-234 were 153+/-9.8, 7+/-0.38, 152+/-10.4 Bq/kg, respectively. The average radiochemical recovery (%) of the destructive alpha-particle measurements is approximately 70% with a resolution (FWHM) of approximately 30 keV. Activity ratios of U-238/Ra-226 and U-238/Pb-210 were less than unity (i.e., index (Ra-Eq>370 Bq/kg), total absorbed gamma dose rate (D(gamma r)>5 nGy/h) and radon emanation fraction (Rn-EF>20%). Uncertainty of the sample counting was 95% confidence level of sigma. The results indicated the necessity to find suitable routes to decrease and/or redistribute the radionuclide of environmental interest (i.e., Ra-226) in PG wastes, consequently to reduce its radiation impacts in the surrounding environment.

  6. Lead immobilization using phosphoric acid in a smelter-contaminated urban soil.

    Science.gov (United States)

    Yang, J; Mosby, D E; Casteel, S W; Blanchar, R W

    2001-09-01

    Transformation of soil lead (Pb) to pyromorphite, a lead phosphate, may be a cost-effective remedial strategy for immobilizing soil Pb and reducing Pb bioavailability. Soil treatment using phosphoric acid (H3PO4) was assessed for its efficacy to reduce Pb solubility and bioaccessibility. Soil containing 4,360 mg of Pb kg(-1), collected from a smelter-contaminated site in Joplin, MO, was reacted with 1,250, 2,500, 5,000, and 10,000 mg of P kg(-1) as H3PO4. The reaction was followed by measurements of Pb bioaccessibility, solubility products, and microprobe analyses. Soluble Pb concentration in the soil decreased with increasing H3PO4 addition. Adding 10,000 mg of P kg(-1) reduced bioaccessible Pb by 60%. The logarithm of bioaccessible Pb decreased as a linear function of increasing H3PO4 addition with an R2 of 0.989. A higher soil/solution ratio was required to extract bioaccessible Pb after the treatment. Microprobe analyses showed that the Pb particles contained P and Cl after the reaction, and the spectra generated by the wavelength-dispersive spectrometer were similar to those of synthetic chloropyromorphite. Lead solubility in the P-treated soil was less than predicted for hydroxypyromorphite [Pbs(PO4)3-OH] and greater than predicted for chloropyromorphite [Pbs(PO4)3Cl]. The P treatment caused approximately 23% redistribution of soil Pb from the clay and silt size fractions to the sand fraction. Soil treatment with H3PO4 resulted in the formation of a compound similar to chloropyromorphite and reduced bioaccessibility of soil Pb, which may have a potential as an in situ technique for Pb-contaminated soil remediation.

  7. Enhancing phosphorus uptake and yield of wheat with phosphoric acid application in calcareous soil.

    Science.gov (United States)

    Hashmi, Zafar Ul Haq; Khan, Muhammad Jamal; Akhtar, Muhammad; Sarwar, Tahir; Khan, Mohammad Jamal

    2017-04-01

    Low phosphorus (P) availability to wheat from commercial fertilizers is one of the reasons for lower grain yield and hence justifies search for more efficient P source under alkaline calcareous soils. Phosphoric acid (PA) and diammonium phosphate (DAP), applied through conventional and modified methods, were assessed for P supply and wheat yield in a calcareous soil. Under laboratory conditions, pre-incubated soil with 70 mg P kg -1 soil as PA and DAP was assessed for solution P (C p ) for 4 weeks. Phosphorus sorption data were fitted using the Freundlich model for describing analyzed sorption in soil incubated with or without DAP and PA. The fitted model equations exhibited comparatively higher effluxes of P from the solution system in control treatment. Compared to DAP, lower quantities (19.6%) of P for PA-treated soil were required for producing optimum P concentration in soil solution, i.e. 0.2 mg P L -1 . The greenhouse study involved 32 P tracer technique to quantify the proportion of applied P derived by wheat from fertilizer or soil. The results showed that P derived from fertilizer was highest (47.5%) in PA placement, while the lowest (31.5%) was in DAP broadcast treatment. The field study also showed similar trends to that of the greenhouse study. The PA placement treatment resulted in highest (23.4%) phosphorus use efficiency, whereas the lowest one (17.1%) was recorded for DAP broadcast treatment. PA proved to be a better P source than DAP for improving P content and achieving higher yield and recovery of applied P by wheat grown in alkaline calcareous soils. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  8. The durability of phosphoric acid promoted bioglass-dentin interaction layer.

    Science.gov (United States)

    Bakry, A S; Takahashi, H; Otsuki, M; Tagami, J

    2013-04-01

    Phosphoric acid-Bioglass 45S5 paste can create an interaction layer formed of calcium-phosphate crystals on the dentin surface. In this study, the efficiency of decreasing the dentin permeability exerted by the interaction layer formed between bioglass and dentin was compared to a resin-containing oxalate desensitizing agent (MS Coat One) and a resin-free oxalate desensitizing agent (Super Seal). Dentin permeability was measured before/after a brushing abrasion challenge, followed by examining the top and the fractured dentin surfaces with a field emission scanning electron microscope. Moreover, the chemical nature of the compounds formed on top of the dentin surface was examined using the field emission scanning electron microscope (FE-SEM) equipped with an energy-dispersive X-ray spectroscope (EDS), and the crystalline structures of the dentinal surfaces were examined by X-ray diffraction (XRD). The results showed that application of 45S5 bioglass paste to dentin was able to occlude patent dentinal tubule orifices with a layer of calcium-phosphate crystals, while the oxalate containing agents were able to form small crystals which were found in dentinal tubule orifices and scattered along the superficial parts of the dentinal tubule lumen. The brushing-abrasion challenge significantly increased the permeability of dentin treated by Super Seal and MS Coat One, while these challenges had no significant effect on the dentin permeability of specimens treated with 45S5 bioglass paste. The new technique provided better durability than two products available on the market. Moreover, our previous research showed the biocompatibility of using this technique on dental pulp cells, suggesting that this technique can aid in treating dentin hypersensitivity cases. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  9. Spectrophotometric and potentiometric studies of oxidation of Mo(III) by Mo(VI) in phosphoric acid medium

    International Nuclear Information System (INIS)

    Kumar, Arvind; Verma, G.S.P.

    1975-01-01

    Oxidation of Mo(III) (green) by Mo(VI) in an inert atmosphere and in orthophosphoric acid medium at various acid concentrations is reported. Potentiometric and spectrophotometric data suggest that oxidation of Mo(III) proceeds to Mo(V) through a binuclear species Mo(III) Mo(IV) absorbing at 400 nm. The formation of this species is facilitated at high acid concentrations. It is further found that quantitative conversion of Mo(III) into Mo(V) takes place at fairly high acid concentrations. In high phosphoric acid concentrations, solution of Mo(III) has been found to be oxidized to Mo(VI) by air and hence this can be used as a good oxygen absorber. (author)

  10. Systematically controlled pore system of ordered mesoporous carbons using phosphoric acid as the in situ generated catalysts for carbonization and activation

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Xing; Lee, Chang Hyun; Kim, Jin Hoe; You, Dae Jong; Shon, Jeong Kuk; Kim, Ji Man [Dept. of Chemistry, Sungkyunkwan University, Suwon (Korea, Republic of); Pak, Chan Ho [Fuel Cell Group, Corporate R and D Center, Samsung SDI Co. Ltd., Yongin (Korea, Republic of)

    2015-08-15

    We report on a facile synthesis of the ordered mesoporous carbon (OMC) materials with systematically controlled microporosity and mesoporosity simultaneously through the nano-replication route using phosphoric acid as the acid catalyst and activation agent. The use of phosphoric acid affects the pore structures of OMC materials, such as the formation of numerous micropores by activation of the carbon framework and the enlargement of mesopores by spontaneous phase separation during the carbonization. The mesopore sizes, surface areas, total pore volumes, and micropore volumes of the OMC materials are highly dependent on the phosphoric acid content and can be systematically controlled in the range 3.7–7.5 nm, 1027–2782 m{sup 2} g{sup -1}, 1.12–3.53 cm{sup 3} g{sup -1} and 0.34–0.95 cm{sup 3} g{sup -1}, respectively. OMC materials with systematically controlled pore structures were successfully synthesized using phosphoric acid as the carbonization catalyst and mesoporous silica materials with cubic Ia3d and 2-D hexagonal mesostructures as the templates. The phosphoric acid in the synthesis of ordered mesoporous carbon materials acts as the chemical activating agent for micropore generation of the carbon framework and pore-expanding agent for controlling of mesopore size, in addition to functioning as the acid catalyst. The present synthesis pathway is very useful for preparing OMC materials with tunable mesopore sizes and well-developed microporosities at the same time.

  11. Studies on the interference of hydrofluoric acid and phosphoric acid in the determination of uranium using Ti(III) reduction method-biamperometry end point

    International Nuclear Information System (INIS)

    Shiny, T.S.; Rajalakshmi, A.; Phal, D.G.; Charyulu, M.M.; Ramakumar, K.L.

    2007-01-01

    Accurate and precise determination of uranium in nuclear materials is necessary for chemical quality control as well as for nuclear material accounting purposes. Different types of uranium samples are received for the measurements. Depending upon the nature of the sample dissolution procedure is selected. Mixed oxide samples of uranium and plutonium, for example, are dissolved in nitric acid containing hydrofluoric acid under IR lamp. The fluoride ions are removed by repeated evaporation of the solution. However, some fluoride ions are left in the solutions depending on the conditions of evaporation. Uranium samples and alloy samples are dissolved in dilute hydrochloric acid. The rate of dissolution depends on concentration of acid. Sometimes a mixture of hydrochloric acid and hydrofluoric acid is used for the dissolution metal alloy samples, which may contain silica. Another method of dissolution of these samples is using a mixture of phosphoric acid and 1% hydrofluoric acid. It is necessary to study the interference of hydrofluoric acid and phosphoric acid on the determination of uranium

  12. The Effect of Phosphoric Acid Pre-etching Times on Bonding Performance and Surface Free Energy with Single-step Self-etch Adhesives.

    Science.gov (United States)

    Tsujimoto, A; Barkmeier, W W; Takamizawa, T; Latta, M A; Miyazaki, M

    2016-01-01

    The purpose of this study was to evaluate the effect of phosphoric acid pre-etching times on shear bond strength (SBS) and surface free energy (SFE) with single-step self-etch adhesives. The three single-step self-etch adhesives used were: 1) Scotchbond Universal Adhesive (3M ESPE), 2) Clearfil tri-S Bond (Kuraray Noritake Dental), and 3) G-Bond Plus (GC). Two no pre-etching groups, 1) untreated enamel and 2) enamel surfaces after ultrasonic cleaning with distilled water for 30 seconds to remove the smear layer, were prepared. There were four pre-etching groups: 1) enamel surfaces were pre-etched with phosphoric acid (Etchant, 3M ESPE) for 3 seconds, 2) enamel surfaces were pre-etched for 5 seconds, 3) enamel surfaces were pre-etched for 10 seconds, and 4) enamel surfaces were pre-etched for 15 seconds. Resin composite was bonded to the treated enamel surface to determine SBS. The SFEs of treated enamel surfaces were determined by measuring the contact angles of three test liquids. Scanning electron microscopy was used to examine the enamel surfaces and enamel-adhesive interface. The specimens with phosphoric acid pre-etching showed significantly higher SBS and SFEs than the specimens without phosphoric acid pre-etching regardless of the adhesive system used. SBS and SFEs did not increase for phosphoric acid pre-etching times over 3 seconds. There were no significant differences in SBS and SFEs between the specimens with and without a smear layer. The data suggest that phosphoric acid pre-etching of ground enamel improves the bonding performance of single-step self-etch adhesives, but these bonding properties do not increase for phosphoric acid pre-etching times over 3 seconds.

  13. The immiscible aqueous solutions of alkyl phosphates. Study for the purpose of uranium extraction from phosphoric acid solutions

    International Nuclear Information System (INIS)

    Mauborgne, Bernard

    1979-01-01

    Systems of immiscible aqueous solutions composed by a phase rich in mineral salt and by another phase almost totally containing an organic salt, have been studied for years, with quaternary ammonium salts with an organic cation. The objective of this research is to study systems symmetric to the previous ones, i.e. with organic anions such as alkyl phosphates, and then to try to understand mechanisms of extraction of metals in these environments. Based on properties of immiscible aqueous solutions, an original three-phase process of liquid-liquid extraction has been developed, and is used to separate uranium in phosphoric acids with better performance than the existing industrial processes [fr

  14. Characterization of phosphogypsum wastes associated with phosphoric acid and fertilizers production

    Energy Technology Data Exchange (ETDEWEB)

    El Afifi, E.M.; Hilal, M.A. [Department of Analytical and Environmental Control, Hot Laboratories and Waste Management Center (HLWMC), Atomic Energy Authority, Post Office No. 13759, Abu Zabaal, Cairo (Egypt); Attallah, M.F. [Department of Analytical and Environmental Control, Hot Laboratories and Waste Management Center (HLWMC), Atomic Energy Authority, Post Office No. 13759, Abu Zabaal, Cairo (Egypt)], E-mail: mohamedfathy_79@yahoo.com; EL-Reefy, S.A. [Department of Analytical and Environmental Control, Hot Laboratories and Waste Management Center (HLWMC), Atomic Energy Authority, Post Office No. 13759, Abu Zabaal, Cairo (Egypt)

    2009-05-15

    The present work is directed to characterize the phosphogypsum (PG) wastes associated with phosphoric acid produced by the wet process in industrial facility for the production of fertilizers and chemicals in Egypt. The PG waste samples were characterized in terms of spectroscopic analysis (X-ray diffraction, X-ray fluorescence, IR spectra) and radiometric analysis ({gamma}- and {alpha}-measurements). The {gamma}-ray measurements showed that the average activity concentrations are 140 {+-} 12.6, 459 {+-} 36.7, 323 {+-} 28.4, 8.3 {+-} 0.76 and 64.3 {+-} 4.1 Bq/kg for U-238, Ra-226, Pb-210, Th-232 and K-40, respectively. The {alpha}-particle measurements of uranium isotopes showed that the average activity concentrations of U-238, U-235 and U-234 were 153 {+-} 9.8, 7 {+-} 0.38, 152 {+-} 10.4 Bq/kg, respectively. The average radiochemical recovery (%) of the destructive {alpha}-particle measurements is {approx}70% with a resolution (FWHM) of {approx}30 keV. Activity ratios of U-238/Ra-226 and U-238/Pb-210 were less than unity (i.e., <1) and equal to 0.31 {+-} 0.02 and 0.47 {+-} 0.16, respectively. The isotopic ratios of U-238/U-235 and U-238/U-234 (in PG and PR samples) were close to the normal values of {approx}21.7 and {approx}1, respectively and are not affected by the wet processing of phosphate rock (PR). The obtained results of PG waste samples were compared with phosphate rock (PR) samples. The radiation hazard indices are namely, radium activity index (Ra-Eq > 370 Bq/kg), total absorbed gamma dose rate (D{sub {gamma}}{sub r} > 5 nGy/h) and radon emanation fraction (Rn-EF > 20%). Uncertainty of the sample counting was 95% confidence level of {sigma}. The results indicated the necessity to find suitable routes to decrease and/or redistribute the radionuclide of environmental interest (i.e., Ra-226) in PG wastes, consequently to reduce its radiation impacts in the surrounding environment.

  15. Porous polybenzimidazole membranes doped with phosphoric acid: Preparation and application in high-temperature proton-exchange-membrane fuel cells

    International Nuclear Information System (INIS)

    Li, Jin; Li, Xiaojin; Yu, Shuchun; Hao, Jinkai; Lu, Wangting; Shao, Zhigang; Yi, Baolian

    2014-01-01

    Highlights: • Porous polybenzimidazole membrane was prepared with glucose as porogen. • Phosphoric acid content was as high as 15.7 mol H 3 PO 4 per PBI repeat unit. • 200 h Constant current density test was carried out at 150 °C. • Degradation was due to the gap between membrane and catalyst layer. - Abstract: In this paper, the preparation and characterization of porous polybenzimidazole membranes doped with phosphoric acid were reported. For the preparation of porous polybenzimidazole membranes, glucose and saccharose were selected as porogen and added into PBI resin solution before solvent casting. The prepared porous PBI membranes had high proton conductivity and high content of acid doping at room temperature with 15.7 mol H 3 PO 4 per PBI repeat unit, much higher than pure PBI membrane at the same condition. Further, the performance and stability of the porous PBI membrane in high-temperature proton-exchange-membrane fuel cells was tested. It was found that the cell performance remained stable during 200 h stability test under a constant current discharge of 0.5 A cm −2 except for the last fifty hours. The decay in the last fifty hours was ascribed to the delamination between the catalyst layer and membrane increasing the charge-transfer resistance

  16. Elementary Acid Rain Kit, Interdisciplinary, Grades 4-8.

    Science.gov (United States)

    Stubbs, Harriett S.; And Others

    An interdisciplinary approach for teaching about acid rain is offered in this curriculum guide for teachers of grades 4-8. Skill and concept areas of science, math, social studies, art, and the language arts are developed in 12 activities which focus on the acid rain problems. A matrix of the activities and subject areas indicates the coverage…

  17. Inorganic polymers from laterite using activation with phosphoric acid and alkaline sodium silicate solution: Mechanical and microstructural properties

    International Nuclear Information System (INIS)

    Enzo Ferrari, Università degli studi di Modena e Reggio Emilia, Via Vignolese 905/a, I-41125 Modena (Italy))" data-affiliation=" (Dipartimento di Ingegneria Enzo Ferrari, Università degli studi di Modena e Reggio Emilia, Via Vignolese 905/a, I-41125 Modena (Italy))" >Lassinantti Gualtieri, Magdalena; Enzo Ferrari, Università degli studi di Modena e Reggio Emilia, Via Vignolese 905/a, I-41125 Modena (Italy))" data-affiliation=" (Dipartimento di Ingegneria Enzo Ferrari, Università degli studi di Modena e Reggio Emilia, Via Vignolese 905/a, I-41125 Modena (Italy))" >Romagnoli, Marcello; Pollastri, Simone; Gualtieri, Alessandro F.

    2015-01-01

    Geopolymers from laterite, an iron-rich soil available in developing countries, have great potential as building materials. In this work, laterite from Togo (Africa) was used to prepare geopolymers using both phosphoric acid and alkaline sodium silicate solution. Microstructural properties were investigated by scanning electron microscopy, X-ray powder diffraction and mercury porosimetry, whereas thermal properties were evaluated by thermal analyses. The local environment of iron was studied by X-ray Absorption Spectroscopy (XANES region). The mechanical properties were determined. Modulus of Rupture and Young's modulus fell in the ranges 3.3–4.5 MPa and 12–33 GPa, respectively, rendering the materials good candidates for construction purposes. Heating above 900 °C results in weight-gain, presumably due to iron redox reactions. X-ray Absorption Spectroscopy data evidence changes in the chemical and structural environments of iron following thermal treatment of geopolymers. These changes indicate interaction between the geopolymer structure and iron during heating, possibly leading to redox properties. -- Highlights: •Geopolymerization of laterite is promising for fabrication of building materials. •Both phosphoric acid and alkaline sodium silicate solution can be used for activation. •Thermally activated redox properties of the inorganic polymers were observed

  18. Inorganic polymers from laterite using activation with phosphoric acid and alkaline sodium silicate solution: Mechanical and microstructural properties

    Energy Technology Data Exchange (ETDEWEB)

    Lassinantti Gualtieri, Magdalena, E-mail: magdalena.gualtieri@unimore.it [Dipartimento di Ingegneria " Enzo Ferrari" , Università degli studi di Modena e Reggio Emilia, Via Vignolese 905/a, I-41125 Modena (Italy); Romagnoli, Marcello [Dipartimento di Ingegneria " Enzo Ferrari" , Università degli studi di Modena e Reggio Emilia, Via Vignolese 905/a, I-41125 Modena (Italy); Pollastri, Simone; Gualtieri, Alessandro F. [Dipartimento di Scienze Chimiche e Geologiche, Università degli studi di Modena e Reggio Emilia, Via S. Eufemia 19I, I-41121 Modena (Italy)

    2015-01-15

    Geopolymers from laterite, an iron-rich soil available in developing countries, have great potential as building materials. In this work, laterite from Togo (Africa) was used to prepare geopolymers using both phosphoric acid and alkaline sodium silicate solution. Microstructural properties were investigated by scanning electron microscopy, X-ray powder diffraction and mercury porosimetry, whereas thermal properties were evaluated by thermal analyses. The local environment of iron was studied by X-ray Absorption Spectroscopy (XANES region). The mechanical properties were determined. Modulus of Rupture and Young's modulus fell in the ranges 3.3–4.5 MPa and 12–33 GPa, respectively, rendering the materials good candidates for construction purposes. Heating above 900 °C results in weight-gain, presumably due to iron redox reactions. X-ray Absorption Spectroscopy data evidence changes in the chemical and structural environments of iron following thermal treatment of geopolymers. These changes indicate interaction between the geopolymer structure and iron during heating, possibly leading to redox properties. -- Highlights: •Geopolymerization of laterite is promising for fabrication of building materials. •Both phosphoric acid and alkaline sodium silicate solution can be used for activation. •Thermally activated redox properties of the inorganic polymers were observed.

  19. Deciphering the role and nature of phosphate species at the surface of stainless steel immersed in phosphoric acid solutions

    Science.gov (United States)

    Liascukiene, I.; Ben Salah, M.; Sabot, R.; Refait, Ph.; Dhouibi, L.; Méthivier, C.; Landoulsi, J.; Jeannin, M.

    2018-03-01

    We investigate the evolution of the surface of a highly alloyed stainless steel (Sanicro 28) upon immersion in aqueous phosphoric acid solutions. For this purpose, both short- (few hours) and long-term immersion (several days) were carried out. A detailed analysis of XPS spectra allowed a distinction to be made between oxygen originating from the organic adlayer (adventitious contamination), the passive oxide layer, and adsorbed phosphate species. By estimating the fraction of oxygen due to phosphate species (Oph), it was shown that the Oph/P molar concentration ratio was ranging from about 2 to 3. This suggests the presence of a polyphosphate layer at the stainless steel surface, as also supported by Raman analysis, which influence the electrochemical behavior of SS in the acidic media.

  20. The effect of phosphoric and phosphonic acid primers on bone cement bond strength to total hip stem alloys.

    Science.gov (United States)

    Jakubowitz, Eike; Liehn, Louisa; Jahnke, Alexander; Wöstmann, Bernd; Rickert, Markus; Niem, Thomas

    2017-05-01

    Aseptic loosening at alloy-cement interfaces constitutes a main failure mechanism of cemented total hip replacements (THR). As a potential solution we investigated the effect of metal primers containing phosphoric and phosphonic acid on shear bond strength (SBS) of bone cement to THR alloys (CoCrMo, TiAlNb) and pure tin (Sn) substrates (20×8×3 mm). Metal surfaces were modified by polishing or Al 2 O 3 blasting and primer application. Substrates without primer treatment served as references. Cylindrical cement pins (Ø 5mm) were polymerised onto substrate surfaces and aging (1, 5, 14 and 150 days) was simulated in aqueous NaCl solution (0.9%) before SBS determination and failure mode evaluation. Regardless of surface roughness and aging time, SBS for THR alloys and Sn was always significantly higher with primer treatment. Compared to untreated reference specimens (≤0.2MPa) SBS values increased even up to 350 fold (TiAlNb, 14 days) or 400 fold (CoCrMo, 5 days). In general, the phosphoric acid containing primer revealed significant higher SBS values on THR alloys compared to the phosphonic acid containing one. Al 2 O 3 blasted specimens showed generally higher SBS values than polished ones with the exception of Sn which showed high SBS values in general. With primer treatment on polished Sn a significant reduction of SBS could not be detected even up to 150 days, whereas THR alloys showed only an SBS improvement in the short term (≤14 days). A NaCl-pitting corrosion probably led to an increasing and durable SBS on polished Sn surfaces over time. Compared to modern THR in clinical practice that shows survival rates of 10, 15, 20 or more years, the receivable bond strength enhancements described in this study appeared to be very short. The improved SBS on THR alloys lasted only a few days before it was lost again. In contrast, the phosphoric acid primer treatment of polished Sn appeared to be very promising and may play a key role in further investigations dealing

  1. Influence of the organic solvents on the properties of the phosphoric acid dopant emulsion deposited on multicrystalline silicon wafers

    International Nuclear Information System (INIS)

    Bouhafs, D; Moussi, A; Boumaour, M; Abaidia, S E K; Mahiou, L; Messaoud, A

    2007-01-01

    This study is devoted to the formation of an n + p emitter for multicrystalline silicon (mc-Si) solar cells for photovoltaic (PV) application. The atomization technique has been used to make the emitter from H 3 PO 4 phosphoric acid as a doping source. The doping emulsion has been optimized using several organic solvents. H 3 PO 4 was mixed with one of these solutions: ethanol, 2-butanol, isopropanol alcohol and deionized water. The volume concentration of H 3 PO 4 does not exceed 20% of the total volume emulsion. The deposit characteristics of the emulsion change with the organic solvent. H 3 PO 4 : 2-butanol gives the best deposited layer with acceptable adherence and uniformity on silicon surface. Fourier transform infrared characterizations show the presence of organic and mineral phosphorous bonds in the formed layer. The obtained emitters are characterized by a junction depth in the range 0.2-0.75 μm and a sheet resistance of about 10-90 Ω/□. Such a low cost dopant source combined with a continuous spray process can effectively reduce the cost per Wp of the PV generator

  2. {sup 230}Th, {sup 232}Th and {sup 238}U determinations in phosphoric acid fertilizer and process products by ICP-MS

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, Marcos R.L. do; Guerreiro, Luisa M.R.; Bonifacio, Rodrigo L.; Taddei, Maria H.T., E-mail: pmarcos@cnen.gov.br [Comissao Nacional de Energia Nuclear (LAPOC/CNEN-MG), Pocos de Caldas, MG (Brazil). Laboratorio de Pocos de Caldas

    2015-07-01

    Through processing of Santa Quiteria-CE mine phosphate rock, Brazil has established a project for production of phosphoric acid fertilizer and uranium as a by-product. Under leaching conditions of phosphate rock with sulfuric acid, which is the common route for preparing phosphoric acid fertilizer, a large part of uranium, thorium and their decay products naturally present in the rock are solubilized. In order to assess the contamination potential in phosphoric acid and others process products, this paper describes a previous precipitation and direct methods for routine analysis of thorium and uranium isotopes by ICP-MS. In all samples, {sup 230}Th, {sup 232}Th and {sup 238}U were directly determined after dilution, except {sup 230}Th in phosphoric acid loaded with uranium sample, which to overcome equipment contamination effect, was determined after its separation by oxalate precipitation using lanthanum as a carrier. The results obtained by the proposed method by ICP-MS, were in good agreement when compared to alpha spectrometry for {sup 230}Th, and ICP-OES and spectrophotometry with arsenazo III for elementary uranium and thorium determinations. (author)

  3. TOWARDS A RATIONAL DESIGN FOR RESOLVING AGENTS .5. SUBSTITUENT EFFECTS IN THE RESOLUTION OF EPHEDRINE USING A SERIES OF CYCLIC PHOSPHORIC-ACIDS

    NARCIS (Netherlands)

    VANDERHAEST, AD; WYNBERG, H; LEUSEN, FJJ; BRUGGINK, A

    The effects of various aromatic substituents in both ephedrine and a cyclic phosphoric acid on the quality of resolution via diastereomeric salt formation are investigated. The diastereoselective synthesis of a novel series of chloro-substituted ephedrines is described. These chloroephedrines can be

  4. Isolation and structural characterization of sugarcane bagasse lignin after dilute phosphoric acid plus steam explosion pretreatment and its effect on cellulose hydrolysis

    Science.gov (United States)

    Jijiao Zeng; Zhaohui Tong; Letian Wang; J.Y. Zhu; Lonnie Ingram

    2014-01-01

    The structure of lignin after dilute phosphoric acid plus steam explosion pretreatment process of sugarcane bagasse in a pilot scale and the effect of the lignin extracted by ethanol on subsequent cellulose hydrolysis were investigated. The lignin structural changes caused by pretreatment were identified using advanced nondestructive techniques such as gel permeation...

  5. A new oxidimetric reagent-potassium dichromate in a strong phosphoric acid medium-VIII Potentiometric titration of molybdenum(VI) and vanadium(V).

    Science.gov (United States)

    Muralikrishna, U; Rao, G G

    1968-01-01

    A new titrimetric method is described for the determination of molybdenum(VI) involving prior reduction to Mo(V) with an excess of Fe(II) in a concentrated phosphoric acid solution, followed by titration with dichromate. The titration can be done at room temperature and without protective atmosphere. Uranium interferes, but vanadium may be determined simultaneously.

  6. Natural Radiation in byproducts of the production of phosphoric acid; Radiacao natural em residuos gerados no processo de producao de acido fosforico

    Energy Technology Data Exchange (ETDEWEB)

    Silveira, Marcilei A. Guazzelli da; Cardoso, L.L., E-mail: marcilei@fei.edu.br [Centro Universitario da FEI, Sao Bernardo do Campo, SP (Brazil); Medina, N.H. [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Institutlo de Fisica

    2014-07-01

    Natural radiation is the largest source of radiation exposure to which man is subject. It is formed basically by cosmic radiation and the radionuclides present in the Earth crust, as {sup 40}K and the elements of the decay series of {sup 232}Th and {sup 238}U. Phosphate ores, which constitutes the raw material for the production of phosphoric acid, have a high rate of natural radiation from the decay series of {sup 232}Th and {sup 238}U. Phosphogypsum, which is naturally radioactivity, is a by-product of the production of phosphoric acid by the wet method. For each ton of phosphoric acid it is produced about 4.5 tons of phosphogypsum. This work presents the analysis of samples collected in all stages of the manufacturing process of phosphoric acid, which generates the phosphogypsum. Gamma-ray spectrometry was used to measure the concentration of the elements of the decay series of {sup 232}Th and {sup 238}U. All analyzed samples showed a high concentration of radionuclides, promoting the need for further steps in the process in order to reduce the presence of such radionuclides in the phosphogypsum. The results indicate the radionuclide {sup 238}U has higher contribution in some samples of the intermediate stages of the process. All samples exceeded the international average range of human exposure to terrestrial gamma radiation, which is 0.3 to 1.0 mSv/year. (author)

  7. Adsorption properties of biomass-based activated carbon prepared with spent coffee grounds and pomelo skin by phosphoric acid activation

    Science.gov (United States)

    Ma, Xiaodong; Ouyang, Feng

    2013-03-01

    Activated carbon prepared from spent coffee grounds and pomelo skin by phosphoric acid activation had been employed as the adsorbent for ethylene and n-butane at room temperature. Prepared activated carbon was characterized by means of nitrogen adsorption-desorption, X-ray powder diffraction, scanning electron microscope and Fourier transform infrared spectroscope. It was confirmed that pore structure played an important role during the adsorption testes. Adsorption isotherms of ethylene and n-butane fitted well with Langmuir equation. The prepared samples owned better adsorption capacity for n-butane than commercial activated carbon. Isosteric heats of adsorptions at different coverage were calculated through Clausius-Clapeyron equation. Micropore filling effect was explained in a thermodynamic way.

  8. Effect of sol aging time on the anti-reflective properties of silica coatings templated with phosphoric acid

    Directory of Open Access Journals (Sweden)

    Wen Wen

    Full Text Available Silica anti-reflective coatings have been prepared by a sol–gel dip-coating process using the sol containing phosphoric acid as a pore-forming template. The effect of the aging time of the sol on the anti-reflective properties has been investigated. The surface topography of the silica AR coatings has been characterized. With increasing sol aging time, more over-sized pores larger than 100 nm are formed in the silica coatings. These could act as scattering centers, scattering visible light and thereby lowering transmittance. The optimal aging time was identified as 1 day, and the corresponding silica coatings showed a maximum transmittance of 99.2%, representing an 8% increase compared to the bare glass substrate. Keywords: Thin films, Anti-reflective coatings, Aging, Dip-coating, Sol–gel preparation

  9. Phase Structure Transition and Properties of Salt-Free Phosphoric Acid/Non-ionic Surfactants in Water.

    Science.gov (United States)

    Wang, Lihuan; Zhao, Wenrong; Dong, Renhao; Hao, Jingcheng

    2016-08-23

    Precise control of phase structure transition for the synthesis of multi-dimensional soft materials is a fascinating target in amphiphilic molecule self-assembly. Here, we demonstrate a spontaneous formation of a closely packed lamellar phase consisting of uni- and multi-lamellar vesicles through the incorporation of a small amount of an extractant, di(2-ethylhexyl)phosphoric acid (DEHPA), into the highly swollen, planar lamellar phase of a non-ionic tetraethylene glycol monododecyl ether (C12EO4) surfactant in water. It is figured out that the introduction of negative membrane charges results in the electrostatic repulsion among the lamellae, which suppresses the Helfrich undulation and induces a phase structure transition from planar lamellae to closely packed vesicles. Our results provide important insight into amphiphilic molecule self-assembly, where additives and pH can satisfy the opportunities for the precise tuning of the lamellar structures, which makes a way for the development of lamellar soft materials.

  10. Correlations between the contents of phytic acid and inorganic phosphorous and downy mildew resistance of corn inbred lines

    Directory of Open Access Journals (Sweden)

    Pantipa Na Chiangmai

    2015-10-01

    Full Text Available Seeds of corn inbred lines collected at the National Corn and Sorghum Research Center (NCSRC, Kasetsart University, were analyzed to determine the contents of phytic acid (PA and inorganic phosphorous (InP. These 28 and 29 inbred lines were cultivated at the NCSRC (in the 2008 late rainy season and 2009 early rainy season to evaluate their resistance to corn downy mildew caused by Peronosclerospora sorghi. Results showed that the values of the PA, InP contents and downy mildew infection were statistically different among these inbred lines in both seasons. However, there were no correlations between the contents of either PA or InP and downy mildew infection.

  11. Effects of Chlorine Ions on the Dissolution Mechanism of Cu Thin Film in Phosphoric Acid Based Solution.

    Science.gov (United States)

    Seo, Bo-Hyun; Kim, Byoung O; Seo, Jong Hyun

    2015-10-01

    The dissolution mechanisms of Cu thin film were studied with a focus on the effect of chlorine ion concentrations in mixture solutions of phosphoric and nitric acid. The dissolution behaviors of Cu thin film were investigated by using potentio-dynamic curves and impedance spectroscopy with varying chlorine ion concentrations. The copper dissolution rate decreased and as a result of this change, CuCl, salt films formed on the Cu surface in the presence of chlorine ions in the mixture solution. Such behavior was interpreted as being competitive adsorption between chlorine and nitrate ions on the copper surface. The passive oxide film on the Cu surface was further investigated in detail using X-ray photoelectron spectroscopy in both the absence and presence of differing chlorine ion concentrations.

  12. Natural radionuclides distribution in the products obtained in the phosphoric acid fabrication from the phosphate rock of Itataia, Ceara State, Brazil

    International Nuclear Information System (INIS)

    Fukuma, Henrique Takuji

    1999-11-01

    The Itataia-Ceara deposit is important as the largest uranium reserve presently known in Brazil exhibiting geological characteristics of the phosphorus and uranium association as uraniferous apatite. The total reserve of Itataia is about 13.8 million tons of P 2 O 5 and 142.5 thousand tons of U 3 O 8 . The uranium content in the Itataia phosphate rock is about ten time higher than commercial phosphate rock concentrates produced in the main Brazilian mines. The Itataia phosphate rock was milled in a pilot plant for wet-process phosphoric acid production by dihydrate method. The uranium contained in the phosphoric acid was recovered by solvent extraction using the DEHPA and TOPO mixture as extractant. After separation from the phosphoric acid, the uranium was precipitated as ammonium diuranate. In this work, the distribution of radionuclides with long physical half-life of the 238 U and 232 Th decay series was evaluated in the products and wastes generated during the Itataia phosphate rock milling. The results obtained will be useful to establish the program of environmental and occupational radiological protection for the future Itataia industrial complex. In addition, the knowledge of activity of the radionuclides contained in the uranium-free phosphoric acid that will be commercially available will allow the previous estimation of the radiological impact due to the use of fertilizers produced from this raw material. The radionuclides 226 Ra, 228 Ra and 210 Pb were preferentially concentrated in the phosphogypsum, while 228 Th, 230 Th and 232 Th remained in the phosphoric acid after uranium extraction. (author)

  13. Consequences of enamel preparation with sodium hypochlorite, polyacrylic and phosphoric acids for the bonding of brackets with resin-modified glass ionomer cements

    OpenAIRE

    Trindade, Alessandra Marques; Pereira, Tatiana Bahia Junqueira; Smith Neto, Perrin; Horta, Martinho Campolina Rebello; Pithon, Matheus Melo; Akaki, Emílio; Oliveira, Dauro Douglas

    2013-01-01

    The aim of this study was to evaluate the effects of deproteinization with 5.25% sodium hypochlorite (NaOCl) prior to enamel conditioning with 10% polyacrylic acid (PAA) and 35% phosphoric acid (PA) on the bond strength (BS) of brackets bonded with resin-modified glass ionomer cement (RMGIC). One hundred human premolars extracted for orthodontic reasons were divided into 5 groups (n = 20 in each group): G1 (control), enamel conditioning with PA, application of adhesive and bonding of brackets...

  14. Role of keto–enol tautomerization in a chiral phosphoric acid catalyzed asymmetric thiocarboxylysis of meso-epoxide: a DFT study

    KAUST Repository

    Ajitha, Manjaly John

    2015-09-15

    The mechanism of a chiral phosphoric acid catalyzed thiocarboxylysis of meso-epoxide was investigated by density functional theory (DFT) calculations (M06-2X). The nucleophilic ring opening of epoxide by thiobenzoic acid was found to proceed via a concerted termolecular transition state with a simultaneous dual proton transfer to yield the β-hydroxy thioester product. Electrostatic interactions together with the steric environment inside the chiral catalyst play an important role in determining the enantioselectivity of the reaction.

  15. Food-grade Selection Markers in Lactic Acid Bacteria

    Directory of Open Access Journals (Sweden)

    Song He

    2012-08-01

    Full Text Available Lactic acid bacteria (LAB are generally regarded as safe (GRAS microorganisms and widely used in industry and medicine. We are trying to add additional properties to them by gene engineering. However, the genetically modified bacteria are not acceptable to use in food and medicine due to the presence of antibiotic resistance genes in plasmids. Thus, it is necessary to develop food-grade selection markers. Food-grade markers can be divided into three classes based on their selected characteristics: dominant, complementary and sugar fermentation markers. The developments on these food-grade selection markers were reviewed in order to provide valuable references for the further study. [TAF Prev Med Bull 2012; 11(4.000: 499-510

  16. Radiological, chemical and morphological characterizations of phosphate rock and phosphogypsum from phosphoric acid factories in SW Spain

    International Nuclear Information System (INIS)

    Renteria-Villalobos, Marusia; Vioque, Ignacio; Mantero, Juan; Manjon, Guillermo

    2010-01-01

    In this work, radiological, chemical, and also morphological characterization was performed in phosphate rock and phosphogypsum samples, in order to understand the behavior of toxic elements. Characterization was carried out using X-ray diffraction (XRD), X-ray fluorescence (XRF), gamma spectrometry and scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDX). Our results show that the phosphate rock was mainly composed of fluorapatite, calcite, perovskite, quartz, magnetite, pyrite and kaolinite, whereas phosphogypsum only exhibited dihydrated calcium sulfate. The activity concentration of U-series radioisotopes in phosphate rock was around 1640 Bq/kg. 226 Ra and 210 Pb tend to be distributed into phosphogypsum by up to 80%, whereas the fraction of U-isotopes is 10%. The most abundant trace elements in phosphate rock were Sr, Cr, V, Zn, Y, Ni and Ba. Some elements, such as Ba, Cd, Cu, La, Pb, Se, Sr, Th and Y, were enriched in the phosphogypsum. This enrichment may be attributed to an additional input associated to the sulfuric acid used for the phosphoric acid production. Furthermore, results from SEM-EDX demonstrated that toxic elements are not distributed homogeneously into phosphogypsum. Most of these elements are concentrated in particles <20 μm of high porosity, and could be easily mobilized by leaching and/or erosion.

  17. Radiological, chemical and morphological characterizations of phosphate rock and phosphogypsum from phosphoric acid factories in SW Spain

    Energy Technology Data Exchange (ETDEWEB)

    Renteria-Villalobos, Marusia, E-mail: marusia@us.es [Applied Nuclear Physics Group, University of Seville, ETS Arquitectura, Departamento de Fisica Aplicada, Avda. Reina Mercedes s/n, 41012 Seville (Spain); Advanced Materials Research Center (CIMAV), Miguel de Cervantes 120, 31109 Chihuahua (Mexico); Vioque, Ignacio, E-mail: ivioque@us.es [Applied Nuclear Physics Group, University of Seville, ETS Arquitectura, Departamento de Fisica Aplicada, Avda. Reina Mercedes s/n, 41012 Seville (Spain); Mantero, Juan, E-mail: manter@us.es [Applied Nuclear Physics Group, University of Seville, ETS Arquitectura, Departamento de Fisica Aplicada, Avda. Reina Mercedes s/n, 41012 Seville (Spain); Manjon, Guillermo, E-mail: manjon@us.es [Applied Nuclear Physics Group, University of Seville, ETS Arquitectura, Departamento de Fisica Aplicada, Avda. Reina Mercedes s/n, 41012 Seville (Spain)

    2010-09-15

    In this work, radiological, chemical, and also morphological characterization was performed in phosphate rock and phosphogypsum samples, in order to understand the behavior of toxic elements. Characterization was carried out using X-ray diffraction (XRD), X-ray fluorescence (XRF), gamma spectrometry and scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDX). Our results show that the phosphate rock was mainly composed of fluorapatite, calcite, perovskite, quartz, magnetite, pyrite and kaolinite, whereas phosphogypsum only exhibited dihydrated calcium sulfate. The activity concentration of U-series radioisotopes in phosphate rock was around 1640 Bq/kg. {sup 226}Ra and {sup 210}Pb tend to be distributed into phosphogypsum by up to 80%, whereas the fraction of U-isotopes is 10%. The most abundant trace elements in phosphate rock were Sr, Cr, V, Zn, Y, Ni and Ba. Some elements, such as Ba, Cd, Cu, La, Pb, Se, Sr, Th and Y, were enriched in the phosphogypsum. This enrichment may be attributed to an additional input associated to the sulfuric acid used for the phosphoric acid production. Furthermore, results from SEM-EDX demonstrated that toxic elements are not distributed homogeneously into phosphogypsum. Most of these elements are concentrated in particles <20 {mu}m of high porosity, and could be easily mobilized by leaching and/or erosion.

  18. Solvation of rare earth di-(2-ethylhexyl)phosphates (LnA3) by di-(2-ethylhexyl)phosphoric acid

    International Nuclear Information System (INIS)

    Trifonov, Yu.I.; Legin, E.K.; Suglobov, D.N.

    1993-01-01

    Dissolution of solid rare earth (RE) di-(2-ethylhexyl)phosphates (LnA 3 ) n in octane on addition of di-(2-ethylhexyl)phosphoric acid (HA) is demonstrated to occur through formation of an acidic mixed-ligand complex LnA 2 (AHA). Such a complex is formed in the organic phase after extraction of Ln 3+ by HA solutions in octane with a deficit of HA that leads to precipitation of LnA 3 . The formation constant of LnA 2 (AHA) decreases with increasing lanthanide atomic number. Investigation of the octane solutions of LnA 2 (AHA) by spectroscopic methods (IR, luminescence) demonstrated that the complex is polymeric with neighboring Ln 3+ ions bound to two alkylphosphate bridges and an AHA - chelated to the RE ion. According to the luminescence spectra, the chelate causes great distortion of the LnO 6 coordination sphere. With a large excess of HA, the homoleptic complex Ln(AHA) 3 with three chelating anions and prismatic Ln 3+ coordination is formed

  19. Thermodynamic and structural of the water - dodecane - bis(ethyl-2-hexyl) phosphoric acid and its sodium salt

    International Nuclear Information System (INIS)

    Lovera, Jacqueline

    1985-01-01

    This research thesis reports the study of the appearance and disappearance of the 'third phase' obtained during the salification of the bis(ethyl-2 hexyl) phosphoric acid (HDEHP) diluted in dodecane, by sodium aqueous solutions. After a large bibliographical study on the properties of the intervening compounds (extraction of metallic cation by the acid, parameters influencing the 'third phase' appearance, surfactant properties, direct and inverse micelles, formation of para-crystalline phases), the author presents chemical experimental methods: liquid-liquid extraction tests, tests by the synthetic way, preparation of reactants, dosing method, methods of chemical analysis). Then, she reports and discusses experimental results in terms of determination of phase diagrams at 25 C, of composition by weight of the third phase, of influence of the apolar diluent, and of influence of the electrolyte. Physical experimental methods are then presented (differential calorimetric analysis, NMR, small angle X-ray scattering, light scattering, polarised light microscopy, constrained phase microscopy, photography, infrared spectroscopy, conductometry, transmission electron micrography, volumetric mass measurements, surface and interface tension measurements, viscoelasticity measurements) and their results are discussed and interpreted [fr

  20. Radiological, chemical and morphological characterizations of phosphate rock and phosphogypsum from phosphoric acid factories in SW Spain.

    Science.gov (United States)

    Rentería-Villalobos, Marusia; Vioque, Ignacio; Mantero, Juan; Manjón, Guillermo

    2010-09-15

    In this work, radiological, chemical, and also morphological characterization was performed in phosphate rock and phosphogypsum samples, in order to understand the behavior of toxic elements. Characterization was carried out using X-ray diffraction (XRD), X-ray fluorescence (XRF), gamma spectrometry and scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDX). Our results show that the phosphate rock was mainly composed of fluorapatite, calcite, perovskite, quartz, magnetite, pyrite and kaolinite, whereas phosphogypsum only exhibited dihydrated calcium sulfate. The activity concentration of U-series radioisotopes in phosphate rock was around 1640 Bq/kg. (226)Ra and (210)Pb tend to be distributed into phosphogypsum by up to 80%, whereas the fraction of U-isotopes is 10%. The most abundant trace elements in phosphate rock were Sr, Cr, V, Zn, Y, Ni and Ba. Some elements, such as Ba, Cd, Cu, La, Pb, Se, Sr, Th and Y, were enriched in the phosphogypsum. This enrichment may be attributed to an additional input associated to the sulfuric acid used for the phosphoric acid production. Furthermore, results from SEM-EDX demonstrated that toxic elements are not distributed homogeneously into phosphogypsum. Most of these elements are concentrated in particles <20 microm of high porosity, and could be easily mobilized by leaching and/or erosion. Copyright 2010 Elsevier B.V. All rights reserved.

  1. Optimizing Available Phosphorus in Calcareous Soils Fertilized with Diammonium Phosphate and Phosphoric Acid Using Freundlich Adsorption Isotherm

    Directory of Open Access Journals (Sweden)

    Asif Naeem

    2013-01-01

    Full Text Available In calcareous soils, phosphorus (P retention and immobilization take place due to precipitation and adsorption. Since soil pH is considered a major soil variable affecting the P sorption, an acidic P fertilizer could result in low P adsorption compared to alkaline one. Therefore, P adsorption from DAP and phosphoric acid (PA required to produce desired soil solution P concentration was estimated using Freundlich sorption isotherms. Two soils from Faisalabad and T. T. Singh districts were spiked with 0, 10, and 20 % for 15 days. Freundlich adsorption isotherms ( were constructed, and theoretical doses of PA and DAP to develop a desired soil solution P level (i.e., 0.20 mg L−1 were calculated. It was observed that P adsorption in soil increased with . Moreover, at all the levels of , P adsorption from PA was lower compared to that from DAP in both the soils. Consequently, lesser quantity of PA was required to produce desired solution P, 0.2 mg L−1, compared to DAP. However, extrapolating the developed relationship between soil contents and quantity of fertilizer to other similar textured soils needs confirmation.

  2. Preparation and physical properties of (PVA0.7(NaBr0.3(H3PO4xM solid acid membrane for phosphoric acid – Fuel cells

    Directory of Open Access Journals (Sweden)

    F. Ahmad

    2013-03-01

    Full Text Available A solid acid membranes based on poly (vinyl alcohol (PVA, sodium bromide (NaBr and phosphoric acid (H3PO4 were prepared by a solution casting method. The morphological, IR, electrical and optical properties of the (PVA0.7(NaBr0.3(H3PO4xM solid acid membranes where x = 0.00, 0.85, 1.7, 3.4, 5.1 M were investigated. The variation of film morphology was examined by scanning electron microscopy (SEM studies. FTIR spectroscopy has been used to characterize the structure of polymer and confirms the complexation of phosphoric acid with host polymeric matrix. The temperature dependent nature of ionic conductivity and the impedance of the polymer electrolytes were determined along with the associated activation energy. The ionic conductivity at room temperature was found to be strongly depends on the H3PO4 concentration which it has been achieved to be of the order 4.3 × 10−3 S/cm at ambient temperature. Optical measurements showed a decrease in optical band gap and an increase in band tail width with the increase of phosphoric acid. The data shows that the (PVA0.7(NaBr0.3(H3PO4xM solid acid membrane is promising for intermediate temperature phosphoric acid fuel cell applications.

  3. Phosphoric acid doped AB-PBI membranes and its applications in high temperature PEMFC

    DEFF Research Database (Denmark)

    He, Ronghuan; Qingfeng, Li; Bjerrum, Niels

    2005-01-01

    in a wide temperature range.. The conductivity of the acid doped ab-PBI membranes was studied in a temperature range of 80oC to 200oC under different relative humidity and with different acid doping levels. PEMFC test results indicated that the fuel cell could be operated at temperatures up to 200o...

  4. Phosphoric acid doped polybenzimidazole membranes: Physiochemical characterization and fuel cell applications [PEM fuel cells

    DEFF Research Database (Denmark)

    Qingfeng, Li; Hjuler, Hans Aage; Bjerrum, Niels

    2001-01-01

    to 1600 mol%. Physiochemical properties of the membrane electrolyte have been investigated by measurements of water uptake, acid doping level, electric conductivity, mechanical strength and water drag coefficient. Electrical conductivity is found to be insensitive to humidity but dependent on the acid...

  5. Impact of pH and application time of meta-phosphoric acid on resin-enamel and resin-dentin bonding.

    Science.gov (United States)

    Cardenas, A F M; Siqueira, F S F; Bandeca, M C; Costa, S O; Lemos, M V S; Feitora, V P; Reis, A; Loguercio, A D; Gomes, J C

    2018-02-01

    To evaluate the immediate microshear resin-enamel bond strength (μSBS) and the immediate and 6-month microtensile bond strength (μTBS) and nanoleakage (NL) of the adhesive interface performed by different pHs of 40% meta-phosphoric acid (MPA) were compared with conventional 37% ortho-phosphoric acid (OPA) under different application times. Additionally, the enamel etching patterns were evaluated and the chemical/morphological changes induced by these differents groups were evaluated. One hundred and ninety-eight extracted human molars were randomly assigned into experimental groups according to the combination of independent variables: Acid [37% ortho-phosphoric acid (OPA), 40% meta-phosphoric acid (MPA) at pHs of: 0.5, 1 and 2] and Application Time [7, 15 and 30s]. Enamel-bond specimens were prepared and tested under μSBS. Resin-dentin beams were tested under μTBS tested immediately or after 6-months of water storage. Nanoleakage was evaluated using bonded-beams of each tooth/time-period. Enamel etching pattern and chemical and ultra-morphology analyses were also performed. The μSBS (MPa) data were subjected to a two-way repeated measures ANOVA (Acid vs. Application time). For μTBS, Acid vs application time vs storage time data were subjected to three-way ANOVA and Tukey's test (α = 0.05). MPA pH 0.5 showed μTBS similar to OPA, independently of the application time on enamel (p>0.05) or dentin (p>0.05). OPA provided higher nanoleakage values than MPA (p = 0.003). Significant decreases in TBS and increases in NL were only observed for OPA after 6 months (p = 0.001). An increase in the application time resulted in a more pronounced etching pattern for MPA. Chemical analysis showed that dentin demineralized by MPA depicted peaks of brushite and octacalcium phosphate. MPA exposed less collagen than OPA. However, optimal results for MPA were dependent on pH/application time. The use of 40% meta-phosphoric acid with a pH of 0.5 is an alternative acid

  6. Recovery of valuable metals from waste cathode materials of spent lithium-ion batteries using mild phosphoric acid

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xiangping, E-mail: chenxiangping101@163.com [School of Environmental Science and Engineering, Shaanxi University of Science & Technology, Xi’an 710021 (China); College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Ma, Hongrui, E-mail: mahr@sust.edu.cn [School of Environmental Science and Engineering, Shaanxi University of Science & Technology, Xi’an 710021 (China); Luo, Chuanbao; Zhou, Tao [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China)

    2017-03-15

    Graphical abstract: Cobalt can be directly recovered as Co{sub 3}(PO{sub 4}){sub 2} from waste LiCoO{sub 2} using H{sub 3}PO{sub 4} as leaching and precipitating agent. - Highlights: • Phosphoric acid was innovatively used as leaching and precipitating agent. • Over 99% Co and Li can be separated and recovered in a single leaching step. • Co and Li can be separated under mild conditions of 40 °C and 0.7 M H{sub 3}PO{sub 4}. • Activation energy values for Co and Li are 7.3 and 10.168 kJ/mol. • Cobalt phosphate (97.1% in purity) can be obtained as the leaching product. - Abstract: Sustainable recycling of valuable metals from spent lithium-ion batteries (LIBs) may be necessary to alleviate the depletion of strategic metal resources and potential risk of environmental pollution. Herein a hydrometallurgical process was proposed to explore the possibility for the recovery of valuable metals from the cathode materials (LiCoO{sub 2}) of spent LIBs using phosphoric acid as both leaching and precipitating agent under mild leaching conditions. According to the leaching results, over 99% Co can be separated and recovered as Co{sub 3}(PO{sub 4}){sub 2} in a short-cut process involved merely with leaching and filtrating, under the optimized leaching conditions of 40 °C (T), 60 min (t), 4 vol.% H{sub 2}O{sub 2}, 20 mL g{sup −1} (L/S) and 0.7 mol/L H{sub 3}PO{sub 4}. Then leaching kinetics was investigated based on the logarithmic rate kinetics model and the obtained results indicate that the leaching of Co and Li fits well with this model and the activation energies (Ea) for Co and Li are 7.3 and 10.2 kJ/mol, respectively. Finally, it can be discovered from characterization results that the obtained product is 97.1% pure cobalt phosphate (Co{sub 3}(PO{sub 4}){sub 2}).

  7. A new blue-emitting phosphor, SrZnO{sub 2}:Pb{sup 2+}, synthesized by the adipic acid templated sol-gel route

    Energy Technology Data Exchange (ETDEWEB)

    Manavbasi, A. [Chemical and Metallurgical Engineering, University of Nevada, Mail Stop 388, Reno, NV 89557 (United States); LaCombe, J.C. [Chemical and Metallurgical Engineering, University of Nevada, Mail Stop 388, Reno, NV 89557 (United States)], E-mail: lacomj@unr.edu

    2008-01-15

    A new blue-emitting phosphor, Sr{sub 1-x}Pb{sub x}ZnO{sub 2}, was prepared by a novel adipic acid templated sol-gel route. Photoluminescence and crystalline properties were investigated as functions of calcination temperatures and the Pb{sup 2+} doping levels. It was found that under UV excitation with a wavelength of 283 or 317 nm, the phosphors gave emission from 374 to 615 nm with a peak centered at 451 nm. This broad-band was composed of UV and the visible range was attributed to an impurity-trapped exciton-type emission. The maximum emission intensity of the Sr{sub 1-x}Pb{sub x}ZnO{sub 2} phosphors occurred at a Pb concentration of x=0.01. The decay time was observed to be {approx}33 ms for the compound doped with 1 mol% Pb prepared at 1000 deg. C. Diffuse reflectance spectra revealed the characteristic absorption peaks and the bandgap energy of SrZnO{sub 2} was found to be 3.4 eV. SEM analysis indicated that phosphor particles have an irregularly rounded morphology and the average particle size was found to be approximately 1 {mu}m.

  8. Use of electro-spray ionization mass spectrometry (ESI-MS) for the study of metal (III) extraction by dialkyl phosphoric acid

    Energy Technology Data Exchange (ETDEWEB)

    Leclerc, E.; Berthon, L.; Heres, X.; Gannaz, B.; Berthon, C.; Adnet, J.M

    2004-07-01

    In the framework of nuclear waste reprocessing, separation processes of minor actinide from fission product are developed by CEA. In order to understand the mechanism involved in the extraction process, the complexes ligand - metallic cations formed in organic phase has been characterized. This paper deals with the extraction of lanthanides (III) and actinides (III) cations by dialkyl phosphoric acid (the bis- 1,3-dimethyl-butyl-phosphoric acid). The associative properties of the extractant were studied, the complexes (metal-ligand) present in organic phase were identified and the interactions ligand-metal were characterized. The electro-spray ionization -mass spectrometry (ESI-MS) was used to investigate organic solutions, and the results are compared with those obtained by other techniques like NMR, IRTF and distribution ratio studies. (authors)

  9. Evaluation of efficient glucose release using sodium hydroxide and phosphoric acid as pretreating agents from the biomass of Sesbania grandiflora (L.) Pers.: A fast growing tree legume.

    Science.gov (United States)

    Mund, Nitesh K; Dash, Debabrata; Barik, Chitta R; Goud, Vaibhav V; Sahoo, Lingaraj; Mishra, Prasannajit; Nayak, Nihar R

    2017-07-01

    Sesbania grandiflora (L.) Pers. is one of the fast growing tree legumes having the efficiency to produce around 50tha -1 above ground dry matters in a year. In this study, biomass of 2years old S. grandiflora was selected for the chemical composition, pretreatments and enzymatic hydrolysis studies. The stem biomass with a wood density of 3.89±0.01gmcm -3 contains about 38% cellulose, 12% hemicellulose and 28% lignin. Enzymatic hydrolysis of pretreated biomass revealed that phosphoric acid (H 3 PO 4 ) pretreated samples even at lower cellulase loadings [1 Filter Paper Units (FPU)], could efficiently convert about 86% glucose, while, even at higher cellulase loadings (60FPU) alkali pretreated biomass could convert only about 58% glucose. The effectiveness of phosphoric acid pretreatment was also supported by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared spectroscopy (FTIR) analysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. COMPARATIVE STUDY OF THE SHEAR BOND STRENGTH OF COMPOSITE RESIN TO DENTAL ENAMEL CONDITIONED WITH PHOSPHORIC ACID OR Nd: YAG LASER

    Directory of Open Access Journals (Sweden)

    EDUARDO Carlos de Paula

    1997-01-01

    Full Text Available This study has been focused on a comparison between the shear bond strength of a composite resin attached to dental enamel surface, after a 35% phosphoric acid etching and after a Nd:YAG laser irradiation with 165.8 J/cm2 of energy density per pulse. After etching and attaching resin to these surfaces, the specimens were thermocycled and then underwent the shearing bond strength tests at a speed of 5 mm/min. The results achieved, after statistical analysis with Student's t-test, showed that the adhesion was significantly greater in the 35% phosphoric acid treated group than in the group treated with the Nd:YAG laser, thus demonstrating the need for developing new studies to reach the ideal parameters for an effective enamel surface conditioning as well as specific adhesives and composite resins when Nd:YAG laser is used

  11. Research and development of a phosphoric acid fuel cell/battery power source integrated in a test-bed bus. Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-05-30

    This project, the research and development of a phosphoric acid fuel cell/battery power source integrated into test-bed buses, began as a multi-phase U.S. Department of Energy (DOE) project in 1989. Phase I had a goal of developing two competing half-scale (25 kW) brassboard phosphoric acid fuel cell systems. An air-cooled and a liquid-cooled fuel cell system were developed and tested to verify the concept of using a fuel cell and a battery in a hybrid configuration wherein the fuel cell supplies the average power required for operating the vehicle and a battery supplies the `surge` or excess power required for acceleration and hill-climbing. Work done in Phase I determined that the liquid-cooled system offered higher efficiency.

  12. Influence of duration of phosphoric acid pre-etching on bond durability of universal adhesives and surface free-energy characteristics of enamel.

    Science.gov (United States)

    Tsujimoto, Akimasa; Barkmeier, Wayne W; Takamizawa, Toshiki; Watanabe, Hidehiko; Johnson, William W; Latta, Mark A; Miyazaki, Masashi

    2016-08-01

    The purpose of this study was to evaluate the influence of duration of phosphoric acid pre-etching on the bond durability of universal adhesives and the surface free-energy characteristics of enamel. Three universal adhesives and extracted human molars were used. Two no-pre-etching groups were prepared: ground enamel; and enamel after ultrasonic cleaning with distilled water for 30 s to remove the smear layer. Four pre-etching groups were prepared: enamel pre-etched with phosphoric acid for 3, 5, 10, and 15 s. Shear bond strength (SBS) values of universal adhesive after no thermal cycling and after 30,000 or 60,000 thermal cycles, and surface free-energy values of enamel surfaces, calculated from contact angle measurements, were determined. The specimens that had been pre-etched showed significantly higher SBS and surface free-energy values than the specimens that had not been pre-etched, regardless of the aging condition and adhesive type. The SBS and surface free-energy values did not increase for pre-etching times of longer than 3 s. There were no significant differences in SBS values and surface free-energy characteristics between the specimens with and without a smear layer. The results of this study suggest that phosphoric acid pre-etching of enamel improves the bond durability of universal adhesives and the surface free-energy characteristics of enamel, but these bonding properties do not increase for phosphoric acid pre-etching times of longer than 3 s. © 2016 Eur J Oral Sci.

  13. Effect of temperature on passive film formation of UNS N08031 Cr-Ni alloy in phosphoric acid contaminated with different aggressive anions

    OpenAIRE

    ESCRIVÁ CERDÁN, CLARA; Blasco Tamarit, María Encarnación; García García, Dionisio Miguel; García Antón, José; Akid, R.; Walton, J.

    2013-01-01

    tThe influence of temperature and the effect of aggressive anions on the electrochemical behaviour of UNSN08031 stainless steel in a contaminated phosphoric acid solution were evaluated. Stabilisation of thepassive film was studied by potentiodynamic polarisation curves, potentiostatic tests, electrochemicalimpedance spectroscopy (EIS) measurements, Mott Schottky analysis and X-ray photoelectron spec-troscopy (XPS). The stability of the passive film was found to decrease as temperature increa...

  14. Pretreating wheat straw by phosphoric acid plus hydrogen peroxide for enzymatic saccharification and ethanol production at high solid loading.

    Science.gov (United States)

    Qiu, Jingwen; Ma, Lunjie; Shen, Fei; Yang, Gang; Zhang, Yanzong; Deng, Shihuai; Zhang, Jing; Zeng, Yongmei; Hu, Yaodong

    2017-08-01

    Wheat straw was pretreated by phosphoric acid plus hydrogen peroxide (PHP) for enzymatic hydrolysis and ethanol fermentation at high solid loadings. Results indicated solid loading could reach 20% with 77.4% cellulose-glucose conversion and glucose concentration of 164.9g/L in hydrolysate, it even was promoted to 25% with only 3.4% decrease on cellulose-glucose conversion as the pretreated-wheat straw was dewatered by air-drying. 72.9% cellulose-glucose conversion still was achieved as the minimized enzyme input of 20mg protein/g cellulose was employed for hydrolysis at 20% solid loading. In the corresponding conditions, 100g wheat straw can yield 11.2g ethanol with concentration of 71.2g/L by simultaneous saccharification and fermentation. Thus, PHP-pretreatment benefitted the glucose or ethanol yield at high solid loadings with lower enzyme input. Additionally, decreases on the maximal cellulase adsorption and the direct-orange/direct-blue indicated drying the PHP-pretreated substrates negatively affected the hydrolysis due to the shrinkage of cellulase-size-accommodable pores. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Optimizing Phosphoric Acid plus Hydrogen Peroxide (PHP) Pretreatment on Wheat Straw by Response Surface Method for Enzymatic Saccharification.

    Science.gov (United States)

    Qiu, Jingwen; Wang, Qing; Shen, Fei; Yang, Gang; Zhang, Yanzong; Deng, Shihuai; Zhang, Jing; Zeng, Yongmei; Song, Chun

    2017-03-01

    Wheat straw was pretreated by phosphoric acid plus hydrogen peroxide (PHP), in which temperature, time, and H 3 PO 4 proportion for pretreatment were investigated by using response surface method. Results indicated that hemicellulose and lignin removal positively responded to the increase of pretreatment temperature, H 3 PO 4 proportion, and time. H 3 PO 4 proportion was the most important variable to control cellulose recovery, followed by pretreatment temperature and time. Moreover, these three variables all negatively related to cellulose recovery. Increasing H 3 PO 4 proportion can improve enzymatic hydrolysis; however, reduction on cellulose recovery results in decrease of glucose yield. Extra high temperature or long time for pretreatment was not beneficial to enzymatic hydrolysis and glucose yield. Based on the criterion for minimizing H 3 PO 4 usage and maximizing glucose yield, the optimized pretreatment conditions was 40 °C, 2.0 h, and H 3 PO 4 proportion of 70.2 % (H 2 O 2 proportion of 5.2 %), by which glucose yielded 299 mg/g wheat straw (946.2 mg/g cellulose) after 72-h enzymatic hydrolysis.

  16. On the Analysis of the Mössbauer Spectra of the Rust Converted by Tannic and Phosphoric Acids

    Science.gov (United States)

    Barrero, C. A.; Ríos, J. F.; Morales, A. L.; Bohórquez, A.; Pérez-Alcazar, G.

    2003-06-01

    In previous work, we reported results on the action of rust converters based on a mixture of tannic and phosphoric acids, upon the rust formed on mild steel coupons. There, the rust before and after the application of converters were characterized by room-temperature Mössbauer spectroscopy, among other techniques. The present work is an extension of this one, and additional MS at 77 K, 130 K and 300 K for some samples are presented. Special emphasis is given to the methodology of analysis. Our results confirm previous findings that an important portion of the magnetite remains without conversion. New information was also derived: (i) the converters seem to affect more the magnetite octahedral (B) than the tetrahedral (A) sites; (ii) among the magnetite B sites, the Fe2+ is the most affected; (iii) at least 31% of magnetic goethite at 77 K is transformed by the converter; and (iv) the presence of an additional phase identified as ferrous phosphate, could be resolved un-ambiguously only at these lower temperatures.

  17. (Liquid + liquid) equilibrium data of (water + phosphoric acid + solvents) systems at T = (308.2 and 318.2) K

    International Nuclear Information System (INIS)

    Ghanadzadeh Gilani, H.; Ghanadzadeh Gilani, A.; Shekarsaraee, S.; Uslu, H.

    2012-01-01

    Highlights: ► Phase equilibria of the (water + PA + solvents) systems were investigated. ► Experimental LLE data were correlated with NRTL and UNIQUAC models. ► Distribution coefficients and separation factors were evaluated. - Abstract: Ternary equilibrium data for the mixtures of {water + phosphoric acid + organic solvent (cyclohexane, methylcyclohexane, and toluene)} were determined at T = (308.2 and 318.2) K and atmospheric pressure. Solubility data were determined by the cloud-point titration method. In order to obtain the tie-line data, the concentration of each phase was determined by acidimetric titration, the Karl–Fischer technique, and refractive index measurements. The experimental tie-line data were correlated using the UNIQUAC and NRTL models. The reliability of the experimental data was determined through the Othmer–Tobias and Hand plots. Distribution coefficients and separation factors were evaluated over the immiscibility regions. The Katritzky LSER model was applied to correlate distribution coefficients and separation factors in these ternary systems.

  18. Maximum power output and load matching of a phosphoric acid fuel cell-thermoelectric generator hybrid system

    Science.gov (United States)

    Chen, Xiaohang; Wang, Yuan; Cai, Ling; Zhou, Yinghui

    2015-10-01

    Based on the current models of phosphoric acid fuel cells (PAFCs) and thermoelectric generators (TGs), a new hybrid system is proposed, in which the effects of multi-irreversibilities resulting from the activation, concentration, and ohmic overpotentials in the PAFC, Joule heat and heat leak in the TG, finite-rate heat transfer between the TG and the heat reservoirs, and heat leak from the PAFC to the environment are taken into account. Expressions for the power output and efficiency of the PAFC, TG, and hybrid system are analytically derived and directly used to discuss the performance characteristics of the hybrid system. The optimal relationship between the electric currents in the PAFC and TG is obtained. The maximum power output is numerically calculated. It is found that the maximum power output density of the hybrid system will increase about 150 Wm-2, compared with that of a single PAFC. The problem how to optimally match the load resistances of two subsystems is discussed. Some significant results for practical hybrid systems are obtained.

  19. Comparison of 2-Octanol and Tributyl Phosphate in Recovery of Tungsten from Sulfuric-Phosphoric Acid Leach Solution of Scheelite

    Science.gov (United States)

    Liao, Yulong; Zhao, Zhongwei

    2018-04-01

    Tungsten was recovered from sulfuric-phosphoric acid leach solution of scheelite using 2-octanol and tributyl phosphate (TBP). Approximately 76% of the tungsten and less than 6.2% of the iron were extracted when using 70% 2-octanol, showing good selectivity for tungsten over iron; the tungsten extraction could not be significantly enhanced using a three-stage countercurrent simulation test. Moreover, more than 99.2% of the W and 91.0% of the Fe were extracted when using 70% TBP, showing poor selectivity, but after pretreating the leach solution with iron powder, less than 5.5% of the Fe was extracted. The loaded phases were stripped using deionized water and ammonia solution. The maximum stripping rate of tungsten from loaded 2-octanol was 45.6% when using water, compared with only 13.1% from loaded TBP. Tungsten was efficiently stripped from loaded phases using ammonia solution without formation of Fe(OH)3 precipitate. Finally, a flow sheet for recovery of tungsten with TBP is proposed.

  20. In vitro lead bioaccessibility and phosphate leaching as affected by surface application of phosphoric acid in lead-contaminated soil.

    Science.gov (United States)

    Yang, J; Mosby, D E; Casteel, S W; Blanchar, R W

    2002-11-01

    Phosphate treatment of lead-contaminated soil may be a cost-effective remedial alternative for in situ stabilizing soil Pb and reducing Pb toxicology to human. The leaching behaviors of the P added to soil surface and the effect on subsurface Pb bioaccessibility must be addressed for this remedial technology to be acceptable. A smelter-contaminated soil containing an average of 2,670 mg Pb kg(-1), collected from the Jasper County Superfund Site located in Jasper County, Missouri, was surface treated with 10 g P kg(-1) as phosphoric acid (H(3)PO(4)). Following a simulated column leaching and 90-day treatment of field plots, respectively, bioaccessible Pb, P, and pH in soil profile were measured. Surface treatment using H(3)PO(4) effectively stabilized soil Pb and reduced leachable Pb and the bioaccessibility. Phosphate leached into deeper profile significantly lowered bioaccessible Pb in subsurface. Reduction of Pb bioaccessibility increased as a linear function of increasing soil P. Although surface H(3)PO(4) treatment resulted in an enhanced leaching of added P and may increase potential risk of surface and groundwater pollution, the P leaching under field conditions is very limited. Lime addition following the treatment may reduce the leachability of added P and further immobilize soil Pb.

  1. Field assessment of treatment efficacy by three methods of phosphoric acid application in lead-contaminated urban soil.

    Science.gov (United States)

    Yang, John; Mosby, David

    2006-07-31

    In situ soil treatment using phosphoric acid (H(3)PO(4)) may be an effective remedial technology for immobilizing soil Pb and reducing Pb risk to human health and ecosystem. The treatment efficacy of three H(3)PO(4) application methods was assessed in a smelter-contaminated urban soil located in the Jasper County Superfund Site, Missouri. Soil, with an average of 3529 mg Pb kg(-1) and in the 2- by 4-m plot size, was treated with H(3)PO(4) at a rate of 10 g P kg(-1) in four replicates by each of three methods: rototilling; surface application; pressure injection. Three soil cores, 2.5-cm diameter and 30-cm long, were taken from each plot before and 90 days after treatment and analyzed for soluble P, bioaccessible Pb and solid-Pb speciation. Applications of H(3)PO(4) induced the heterogeneity of soluble P in soil, with the highest concentrations in the surface. Three application methods mixed the H(3)PO(4) more effectively in the horizontals than the verticals of treated soil zone. The H(3)PO(4) applications significantly reduced Pb bioaccessibility in the soil, which was influenced by the concentrations of soil soluble P and solid-Pb species. The risk reductions of soil Pb were achieved by formation of pyromorphites or pyromorphite-like minerals. The rototilling appears to be the most effective treatment method in context of the homogeneity of soluble P and the reduction of Pb bioaccessibility in treated soil.

  2. Development of comprehensive technology of phosphoric acid fuel cell. Research and development of commercial fuel cell power generation system

    Energy Technology Data Exchange (ETDEWEB)

    1987-09-01

    The purpose of this study is to develop a down-sized, easy operation phosphoric acid fuel cell power generation system as a commercial on-site power source for hotel and hospital and to operate the system. The five-year program was initiated in 1986. In FY 1986, the component research such as the moulding process of sheet matrix and electrode for thinner cell and the determination of performance of heat pipe cooler were made. The structure of down-sized reformer and heat-exchanger were investigated. The three-dimensional impeller, material of impeller, gaseous bearing and the structure of soundproof package of the high-performance turbo compressor were studied to determine the basic structure. Hotel A with the floor space of appromixately 50,000 m/sup 2/ was selected to install the system and the demands of power and heat were surveyed. The specifications of a 200 kW-outdoor system were developed based on those results. (2 tabs)

  3. Influence of the solution temperature on the corrosion behavior of an austenitic stainless steel in phosphoric acid medium

    Energy Technology Data Exchange (ETDEWEB)

    Ibanez-Ferrandiz, M.V.; Blasco-Tamarit, E.; Garcia-Garcia, D.M.; Garcia-Anton, J. [Valencia Univ. Politecnica, Dept. de Ingenieria Quimica y Nuclear. ETSI Industriales, Valencia (Spain); Guenbour, A.; Bakour, S.; Benckokroun, A. [University Mohammed V-Agdal, Lab. Corrosion-Electrochimie, Faculty of Sciences, Rabat (Morocco)

    2009-07-01

    The objective of the present work is to study the effect of the solution temperature on the corrosion resistance of a highly alloyed austenitic stainless steel (UNS N08031) used as base metal, the welded metal obtained by TIG (Tungsten Inert Gas) welding using a Nickel-base alloy (UNS N06059) as filler metal, and the Heat Affected Zone (HAZ) of the base metal. The materials were tested in 5.5 M phosphoric acid solution at 25 C, 40 C, 60 C and 80 C. Open Circuit Potential tests and potentiodynamic anodic polarization curves have been carried out to obtain information about the electrochemical behavior of the materials. Corrosion potentials and corrosion current densities were obtained from Tafel analysis. The critic potentials and passivation current densities of the studied materials were also analyzed. The galvanic corrosion generated by the electrical contact between the welded metal, the base metal and the HAZ, was estimated from the polarisation diagrams according to the Mixed Potential Theory. The samples were etched to study their microstructure by Optical Microscopy. Results demonstrated that the corrosion potential values shift to more anodic potentials as temperature increases. The corrosion current densities and the passive current densities increased with temperature. Open circuit potential values were located in the passive zone of the potentiodynamic curves, which means that the materials passivated spontaneously. (authors)

  4. Phosphoric acid doped polybenzimidazole membranes: Physiochemical characterization and fuel cell applications [PEM fuel cells

    DEFF Research Database (Denmark)

    Qingfeng, Li; Hjuler, Hans Aage; Bjerrum, Niels

    2001-01-01

    A polymer electrolyte membrane fuel cell operational at temperatures around 150-200 degrees C is desirable for fast electrode kinetics and high tolerance to fuel impurities. For this purpose polybenzimidazole (PBI) membranes have been prepared and H/sub 3/PO/sub 4/-doped in a doping range from 300...... to 1600 mol%. Physiochemical properties of the membrane electrolyte have been investigated by measurements of water uptake, acid doping level, electric conductivity, mechanical strength and water drag coefficient. Electrical conductivity is found to be insensitive to humidity but dependent on the acid...... doping level. At 160 degrees C a conductivity as high as 0.13 S cm/sup -1/ is obtained for membranes of high doping levels. Mechanical strength measurements show, however, that a high acid doping level results in poor mechanical properties. At operational temperatures up to 190 degrees C, fuel cells...

  5. Significance of the carbonization of volatile pyrolytic products on the properties of activated carbons from phosphoric acid activation of lignocellulosic material

    Energy Technology Data Exchange (ETDEWEB)

    Zuo, Songlin; Yang, Jianxiao; Cai, Xuan [Faculty of Chemical Engineering, Nanjing Forestry University, Nanjing 210037 (China); Liu, Junli [Institute of Chemical Industry of Forest Products, CAF, Nanjing 210042 (China)

    2009-07-15

    Two series of activated carbons derived from China fir (Cunninghamia lanceolata) wood impregnated with phosphoric acid were prepared in a cylindrical container that was kept in a closed state covered with a lid (the covered case) or in an open state. The effects of the carbonization of volatile pyrolytic products of starting materials on the properties of activated carbon were investigated in the process of phosphoric acid activation. Elemental analysis and SEM observation showed that both activating in the covered case and increasing the mass of starting material used favored the carbonization of volatile pyrolytic products. An investigation of N{sub 2} adsorption isotherms revealed that the carbonization of volatile pyrolytic products significantly enhanced mesopore development in the final carbons, especially pores with a size range from 2.5 to 30 nm, with little influence on micropores, and therefore produced a large increase in the adsorption capacity to Vitamin B12 (with a molecular size of 2.09 nm). Activated carbons with highly developed mesopores could be obtained in the covered case. The carbonization mechanism of volatiles was discussed and two different carbonization pathways (in solid and gas phases) were proposed during phosphoric acid activation. (author)

  6. Kinetic study of the precipitation of radioactive elements in the production process of phosphoric acid

    International Nuclear Information System (INIS)

    Ben Mahmoud, Souha

    2009-01-01

    In this engineering study we determined the activities of gamma emitting radionuclides belonging to the families of 238 U , 232 Th and 40K in phosphate, the acid derivatives and gypsum in Tunisian Chemical Group. The most important activities are those of 238 U and 226 Ra, which are located in the phosphate, gypsum and the precipitates formed in the pipes.

  7. Liquid crystalline solutions of cellulose in phosphoric acid for preparing cellulose yarns

    NARCIS (Netherlands)

    Boerstoel, H.

    2006-01-01

    The presen thesis describes a new process for manufacturing high tenacity and high modulus cellulose yarns. A new direct solvent for cellulose has been discovered, leading to liquid crystalline solutions. This new solvent, superphosphoric acid, rapidly dissolves cellulose. These liquid crystalline

  8. Electrochemistry of carbonaceous materials; 2. Anodic electroactivity of coal slurries in 85% phosphoric acid media

    Energy Technology Data Exchange (ETDEWEB)

    Tomat, R.; Salmaso, R.; Zecchin, S. (CNR-Instituto di Polarografia ed Elettrochimica Preparative, Padova (Italy))

    1992-04-01

    Current-potential curves of suspended coal (Sulcis basin, Sardinia, Italy) in 85% H{sub 3}PO{sub 4} were taken on a platinum electrode at 100{degree}C. Anodic current in the potential range of 0-1.5 V versus saturated calomel electrode was due to some humic acid-type substances released by coal in the electrolyte. The leaching of organic matter increased with the lowering of the particle dimensions, and the related oxidation currents attained stable values even during slurry formation. Current-potential curves were still unchanged when coal was filtered off from the suspension. Previous washing of ground coal with diluted mineral acids, including H{sub 3}PO{sub 4}, did not dissolve any significant amount of the substances responsible for the electrochemical activity of the coal sample examined. 14 refs., 6 figs.

  9. Filler masses of zirconium dioxide based on ortho-phosphoric acid

    International Nuclear Information System (INIS)

    Karaulov, A.G.

    1975-01-01

    The paper examines the effect of the content of monoclinal ZrO 2 in ramming mass based on zirconium dioxide, and the quantity of orthophosphoric acid, on the properties of mass over a wide temperature range. The addition of monoclinal ZrO 2 reduces the shrinkage of ramming mass and increases its strength in the range 300 - 1,000 0 C. The introduction of monoclinal ZrO 2 into mass based on partly stabilized ZrO 2 with a maximum grain size of 5 mm ensures a complete absence of shrinkage right up to 1,750 0 C. Such masses, however, have a more marked fall in strength at 1,200 0 C (destabilization temperature of ZrO 2 ). Orthophosphoric acid acts as a surface active agent and improves the density of the samples; increasing its quantity from 2 to 5 % (by weight) increases the strength of ramming mass. (author)

  10. Effects of 401’. Phosphoric Acid Etch on the Compressive Strength of Biodentine

    Science.gov (United States)

    2016-06-10

    cements . ADA specification 96 specifies requirements and test methods for powder/liquid acid-base dental cements intended for permanent cementation ...Bioactivity of Radiopacified Tricalcium Silicate Cement , Biodentine and MTA Angelus . Dental Materials , 580-593. Ceci, M., Beltrami, R., Chiesa, M...Camilleri, J. (2013). Investigation of the Physical Properties of Tricalcium Silicate Cement -Based Root-End FIlling Materials. Dental Materials, 20-28

  11. Determination of specific activity of phosphorus-32 labelled o-phosphoric acid

    International Nuclear Information System (INIS)

    Sane, S.U.

    2015-01-01

    Phosphorus-32 is one of the important radioisotopes used in therapeutic nuclear medicine. This work was aimed at developing a fast and sensitive procedure to determine trace amounts of 32 P which is present in various acidic chemical form thereby enabling to determine its specific activity. The method utilizes ammonium molybdate and metol for complexing with phosphorus in presence of sulphuric acid which was measured using UV-VIS spectrophotometer. The phosphate and molybdate ions form a stable complex which turns blue (molybdenum blue) by reduction with sulphuric acid. The absorbance of the complex thus formed was measured at 700 nm. Five batches of 32 P produced were analyzed using the procedure and specific activity was determined. It was found that radioactivity of 32 P did not interfere in absorbance measurements and the method could be successfully adopted for the determination of specific activity of 32 P. A scope of the method is to find the chemical purity of radioactive phosphorus ( 32 P) in quality control analysis. (author)

  12. Modeling the hydrolysis of perfluorinated compounds containing carboxylic and phosphoric acid ester functions and sulfonamide groups.

    Science.gov (United States)

    Rayne, Sierra; Forest, Kaya

    2010-01-01

    Temperature-dependent rate constants were estimated for the acid- and base-catalyzed and neutral hydrolysis reactions of perfluorinated telomer acrylates (FTAcrs) and phosphate esters (FTPEs), and the S(N)1 and S(N)2 hydrolysis reactions of fluorotelomer iodides (FTIs). Under some environmental conditions, hydrolysis of monomeric FTAcrs could be rapid (half-lives of several years in marine systems and as low as several days in some landfills) and represent a dominant portion of their overall degradation. Abiotic hydrolysis of monomeric FTAcrs may be a significant contributor to current environmental loadings of fluorotelomer alcohols (FTOHs) and perfluoroalkyl carboxylic acids (PFCAs). Polymeric FTAcrs are expected to be hydrolyzed more slowly, with estimated half-lives in soil and natural waters ranging between several centuries to several millenia absent additional surface area limitations on reactivity. Poor agreement was found between the limited experimental data on FTPE hydrolysis and computational estimates, requiring more detailed experimental data before any further modeling can occur on these compounds or their perfluoroalkyl sulfonamidoethanol phosphate ester (PFSamPE) analogs. FTIs are expected to have hydrolytic half-lives of about 130 days in most natural waters, suggesting they may be contributing to substantial FTOH and PFCA inputs in aquatic systems. Perfluoroalkyl sulfonamides (PFSams) appear unlikely to undergo abiotic hydrolysis at the S-N, C-S, or N-C linkages under environmentally relevant conditions, although potentially facile S-N hydrolysis via intramolecular catalysis by ethanol and acetic acid amide substituents warrants further investigation.

  13. A new oxidimetric reagent: potassium dichromate in a strong phosphoric acid medium-VI Potentiometric titration of vanadium(III) alone and in mixture with vanadium(IV).

    Science.gov (United States)

    Rao, G G; Rao, P K

    1966-09-01

    Vanadium(III) can be titrated at room temperature with potassium dichromate in an 8-12M phosphoric acid medium. Two potential breaks are observed in 12M phosphoric add with 0.2N potassium dichromate, the first corresponding to the oxidation of vanadium(III) to vanadium(IV) and the second to the oxidation of vanadium(IV) to vanadium(V). In titrations with 0.05N dichromate only the first break in potential is clearly observed. The method has been extended to the titration of mixtures of vanadium(III) and vanadium(IV). Conditions have also been found for the visual titration of vanadium(III) using ferroln or barium diphenylamine sulphonate as indicator.

  14. Determination of the O/M ratios of polynary uranium oxides by Ce(IV)-Fe(II) back titration after dissolution in mixed sulphuric and phosphoric acids

    International Nuclear Information System (INIS)

    Fujino, T.; Sato, N.; Yamada, K.

    1996-01-01

    Uranium (IV) in polynary uranium oxides is determined after the solid has been dissolved in a warm mixed solution of sulphuric and phosphoric acids containing excess Ce(IV). The latter is titrated with a Fe(II) standard solution using ferroin as indicator. This method is especially effective for (mixed) uranium oxides which are difficult to dissolve in hot Ce(IV) sulphuric acid. The standard deviation of the determined x value in polynary oxides is estimated to be below ± 0.004 for samples of 10-30 mg. (orig.)

  15. Determination of the O/M ratios of polynary uranium oxides by Ce(IV)-Fe(II) back titration after dissolution in mixed sulphuric and phosphoric acids.

    Science.gov (United States)

    Fujino, T; Sato, N; Yamada, K

    1996-01-01

    Uranium (IV) in polynary uranium oxides is determined after the solid has been dissolved in a warm mixed solution of sulphuric and phosphoric acids containing excess Ce(IV). The latter is titrated with a Fe(II) standard solution using ferroin as indicator. This method is especially effective for (mixed) uranium oxides which are difficult to dissolve in hot Ce(IV) sulphuric acid. The standard deviation of the determined x value in polynary oxides is estimated to be below +/- 0.004 for samples of 10-30 mg.

  16. Development of a volumetric Analysis method to determine uranium in the loaded phosphoric acid and the loaded organic phase (DEHPA/TOPO)

    International Nuclear Information System (INIS)

    Shlewit, H.; Koudsi, Y.

    2003-01-01

    Rapid and reliable volumetric analysis method has been developed to determine uranium, on line, at uranium extraction unit from wet-process phosphoric acid, in aqueous and organic phases. This process enable up 300 mg of uranium to be determined in the presence of nitric acid, in a sample volume of up to at least 10 ml. The volume of the sample, the amounts of reagents added, the temperature of the reagents and the standing time of various stages were investigated to ensure that the conditions selected for the final procedure were reasonably non-critical

  17. Effet du biochar sur la biodisponibilité du phosphore dans un sol limoneux acide

    Directory of Open Access Journals (Sweden)

    Houben, D.

    2017-01-01

    Full Text Available Effect of biochar on phosphorus bioavailability in an acidic silt loam soil. Description of the subject. This paper deals with the impact of biochar on soil phosphorus (P bioavailability with a view to improving the management of P fertilization. Objectives. The aim of this study was to explore the potential of biochar to increase P bioavailability in soil. The specific objectives were to elucidate the role of feedstock and the rate of application of biochar on P solubility. Method. Three biochars produced from different feedstocks (Miscanthus straws, coffee husks and woody material were added to an acidic Luvisol at two rates of application (1% and 3%; w/w. At the end of a 76-day incubation period, P bioavailability was assessed (0.01 M CaCl2 extraction. Soil physico-chemical properties and the amount of CO2 emitted over the incubation period were also determined. Results. The wood-derived biochar applied at 3% was the only treatment that increased significantly P bioavailability (+ 75%. This increase might result from the release of P by biochar itself (direct effect but also from an enhanced P solubility in soil (indirect effect related to a large increase in pH (+3.6 units compared to the control and a higher soil biological activity. The other treatments had no significant impact on soil P bioavailability, probably as a result of their minor effect on soil pH. Conclusions. Our study shows that biochar-induced changes in P bioavailability in soil varied greatly with type of feedstock and rate of application. However, the balance between the direct and indirect effects of biochar on P bioavailability was not elucidated. Further investigations are thus essential to clarify the potential of biochar to improve P bioavailability in the soil-plant system.

  18. Surface decoration of polyimide fiber with carbon nanotubes and its application for mechanical enhancement of phosphoric acid-based geopolymers

    Science.gov (United States)

    Yang, Tao; Han, Enlin; Wang, Xiaodong; Wu, Dezhen

    2017-09-01

    A new methodology to decorate the surface of polyimide (PI) fiber with carbon nanotubes (CNTs) has been developed in this study. This surface decoration was carried out through a surface alkali treatment, a carboxylation modification, surface functionalization with acyl chloride groups and then with amino groups, and a surface graft of CNTs onto PI fiber. Fourier-transform infrared and X-ray photoelectron spectroscopic characterizations confirmed that CNTs were chemically grafted onto the surface of PI fiber, and scanning electron microscopic observation demonstrated the fiber surface was uniformly and densely covered with CNTs. The surface energy and wettability of PI fiber were improved in the presence of CNTs on the fiber surface, which made a contribution to enhance the interfacial adhesion of PI fiber with other inorganic matrices when used as a reinforcing fiber. The application of CNTs-decorated PI fiber for the reinforcement of phosphoric acid-based geopolymers was investigated, and the results indicated that the geopolymeric composites gained a noticeable reinforcement. Compared to unreinforced geopolymer, the geopolymeric composites achieved a remarkable increase in compressive strength by 120% and in flexural strength by 283%. Fractography investigation demonstrated that the interaction adhesion between the fibers and matrix was enhanced due to the surface decoration of PI fiber with CNTs, which contributed to an improvement in fracture-energy dissipation by fiber pullout and fiber debonding from the matrix. As a result, a significant reinforcement effect on geopolymeric composites was achieved through a fiber-bridging mechanism. This study provided an effective methodology to improve the interracial bonding force for PI fiber and also proves a highly efficient application of CNTs-decorated PI fiber for the mechanical enhancement of geopolymeric composites.

  19. Luminescence resonance energy transfer-based nucleic acid hybridization assay on cellulose paper with upconverting phosphor as donors.

    Science.gov (United States)

    Zhou, Feng; Noor, M Omair; Krull, Ulrich J

    2014-03-04

    A bioassay based on DNA hybridization on cellulose paper is a promising format for gene fragment detection that may be suited for in-field and rapid diagnostic applications. We demonstrate for the first time that luminescence resonance energy transfer (LRET) associated with upconverting phosphors (UCPs) can be used to develop a paper-based DNA hybridization assay with high sensitivity, selectivity and fast response. UCPs with strong green emission were synthesized and subsequently functionalized with streptavidin (UCP-strep). UCP-strep particles were immobilized on cellulose paper, and then biotinylated single-stranded oligonucleotide probes were conjugated onto the UCPs via streptavidin-biotin linkage. The UCPs served as donors that were LRET-paired with Cy3-labeled target DNA. Selective DNA hybridization enabled the proximity required for LRET-sensitized emission from Cy3, which was used as the detection signal. Hybridization was complete within 2 min, and the limit of detection of the method was 34 fmol, which is a significant improvement in comparison to an analogous fluorescence resonance energy transfer (FRET) assay based on quantum dots. The assay exhibited excellent resistance to nonspecific adsorption of noncomplementary short/long DNA and protein. The selectivity of the assay was further evaluated by one base pair mismatched (1BPM) DNA detection, where a maximum signal ratio of 3.1:1 was achieved between fully complementary and 1BPM samples. This work represents a preliminary but significant step for the development of paper-based UCP-LRET nucleic acid hybridization assays, which offer potential for lowering the limit of detection of luminescent hybridization assays due to the negligible background signal associated with optical excitation by near-infrared (NIR) light.

  20. Removal of arsenic and cadmium with sequential soil washing techniques using Na2EDTA, oxalic and phosphoric acid: Optimization conditions, removal effectiveness and ecological risks.

    Science.gov (United States)

    Wei, Meng; Chen, Jiajun; Wang, Xingwei

    2016-08-01

    Testing of sequential soil washing in triplicate using typical chelating agent (Na2EDTA), organic acid (oxalic acid) and inorganic weak acid (phosphoric acid) was conducted to remediate soil contaminated by heavy metals close to a mining area. The aim of the testing was to improve removal efficiency and reduce mobility of heavy metals. The sequential extraction procedure and further speciation analysis of heavy metals demonstrated that the primary components of arsenic and cadmium in the soil were residual As (O-As) and exchangeable fraction, which accounted for 60% and 70% of total arsenic and cadmium, respectively. It was determined that soil washing agents and their washing order were critical to removal efficiencies of metal fractions, metal bioavailability and potential mobility due to different levels of dissolution of residual fractions and inter-transformation of metal fractions. The optimal soil washing option for arsenic and cadmium was identified as phosphoric-oxalic acid-Na2EDTA sequence (POE) based on the high removal efficiency (41.9% for arsenic and 89.6% for cadmium) and the minimal harmful effects of the mobility and bioavailability of the remaining heavy metals. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Extraction of pentavalent americium by di(2-ethylhexyl)phosphoric acid

    International Nuclear Information System (INIS)

    Molochnikova, N.P.; Myasoedov, B.F.; Frenkel, V.Ya.

    1983-01-01

    Conditions have been found for the extraction of americium(V) by HDEHP in octane from acetate buffer solutions at pH 4.5-5.0 in the presence of ammonium persulphate which was necessary to stabilize oxidized americium under these conditions. The effect of the nature of a solvent on the extraction coefficient of americium(V) was studied. Macroamounts of americium(V) were extracted by 0.5M HDEHP in octane. The absorption spectrum of americium(V) in the extract has been recorded. The stability of americium(V) in the organic phase was evaluated. The absence of interfering influence of the anions of phosphotungstic acids on the extraction of americium(V) by 0.5M HDEHP in octane makes it possible to separate americium(V) from trivalent actinides during one extraction from acetate solutions at pH 4.5-5.0 in the presence of 10 -3 M potassium phosphotungstate; the separation factor is about 10 3 . (author)

  2. Complexes of Cd sup 2 sup +, U(O sub 2 ) sup 2 sup + and Th sup 4 sup + at radiotracer levels with phosphoric acid

    International Nuclear Information System (INIS)

    Bouhlassa, S.; El-Yahyaoui, A.; Brillard, L.; Hussonnois, M.; Guillaumont, R.

    1994-01-01

    In this work, we have turn to account the radiochemical techniques in order to investigate the complexation of Cd sup 2 sup +, U(O sub 2) sup 2 sup + and Th sup 2 sup +, at strength Mu=0,2, in various phosphoric media characterized by C sub ( H sub 3 P O sub 4) <= 4 M and 0.7 <= pH <= 4. The method chosen for this purpose is the liquid-liquid extraction of radioisotopes at tracer scale, with di(2-ethyl hexyl) phosphoric acid dissolved in benzene. The radionuclides used are Cd-109, U-233, U-230 and Th-227. Their distribution between the two phases are established by alpha or gamma spectrometric analysis. The analysis of the distribution data allows to define, in addition of species extracted in organic phase, the nature of phosphoric complexes which take place in aqueous media. Stability constants of these complexes and associated thermodynamic data are determined. 2 tabs.; 2 refs. (author)

  3. Changes in mobility of toxic elements during the production of phosphoric acid in the fertilizer industry of Huelva (SW Spain) and environmental impact of phosphogypsum wastes.

    Science.gov (United States)

    Pérez-López, Rafael; Alvarez-Valero, Antonio M; Nieto, José Miguel

    2007-09-30

    Presently, about 3 million tonnes of phosphogypsum are being generated annually in Spain as by-product from phosphoric acid in a fertilizer factory located in Huelva (southwestern Iberian Peninsula). Phosphate rock from Morocco is used as raw material in this process. Phosphogypsum wastes are stored in a stack containing 100Mt (approximately 1200ha of surface) over salt marshes of an estuary formed by the confluence of the Tinto and Odiel rivers, less than 1km away from the city centre. A very low proportion of this waste is used to improve fertility of agricultural soils in the area of the Guadalquivir river valley (Seville, SW Spain). The chemical speciation of potentially toxic elements (Ba, Cd, Cu, Ni, Sr, U and Zn) in phosphogypsum and phosphate rock was performed using the modified BCR-sequential extraction procedure, as described by the European Community Bureau of Reference (1999). This study has been done with the main of: (1) evaluate changes in the mobility of metals during the production of phosphoric acid; (2) estimate the amount of mobile metals that can affect the environmental surrounding; and (3) verify the environmentally safe use of phosphogypsum as an amendment to agricultural soils. The main environmental concern associated to phosphoric acid production is that Uranium, a radiotoxic element, is transferred from the non-mobile fraction in the phosphate rock to the bioavailable fraction in phosphogypsum in a rate of 23%. Around 21% of Ba, 6% of Cu and Sr, 5% of Cd and Ni, and 2% of Zn are also contained in the water-soluble phase of the final waste. Considering the total mass of phosphogypsum, the amount of metals easily soluble in water is approximately 6178, 3089, 1931, 579, 232, 193 and 77t for Sr, U, Ba, Zn, Ni, Cu and Cd, respectively. This gives an idea of the pollution potential of this waste.

  4. Measurement and modeling of density and viscosity of n-octanol-kerosene-phosphoric acid solutions in a temperature range 293.15-333.15 K

    Science.gov (United States)

    Ye, Changwen; Pei, Xiangjun; Liu, J. C.

    2016-12-01

    Densities and viscosities have been measured for the n-octanol + aviation kerosene (AK) + phosphoric acid (H3PO4) system with the mass fraction of H3PO4 in the range from w = 0 to 0.26 and in the temperature of 293.15-333.15 K. According to the experimental data, the measured viscosities were found well correlated with the temperature and mass fraction of H3PO4, which were fitted to regression equations. The result shows that the dilution effect of AK is obvious under the same temperature and mass fraction of H3PO4.

  5. A new oxidimetric reagent: potassium dichromate in a strong phosphoric acid medium--VII. Photometric titration of vanadium(IV) and of cerium(III) alone and in mixtures with iroN(II).

    Science.gov (United States)

    Rao, G G; Rao, P K

    1967-01-01

    Vanadium(IV) can be accurately titrated with potassium dichromate in media containing phosphoric acid of 3-12M concentration: the change in absorption of vanadium(IV) is followed in the region 660 mmicro using a red filter. It is more convenient to carry out the titration in 3M phosphoric acid because at higher concentrations chloride, nitrate, cerium(III) and manganese(II) may interfere. Photoelcetric titration is more convenient than potentiometric because the former can be made in a 3M phosphoric acid medium, whereas the latter is possible only in 12M phosphoric acid. The simultaneous differential photometric titration of iron(II) and vanadium(IV) is also possible. Conditions have been found for the photometric titration of cerium(III) and of cerium(III) plus iron(II). The titration is carried out (at 450 mmicro or with a blue filter) in about 10.5M phosphoric acid. Application of the method to a cerium mineral is considered.

  6. Recovery of uranium contained in phosphoric acid by a wet method and its transformation in a high-purity uraniferous concentrates

    International Nuclear Information System (INIS)

    Davister, A.; Dubreucq, A.; Granville, G.; Gray, H.

    1984-01-01

    There are altogether three plants in active operation today for the recovery of uranium contained in the phosphoric acid, two in the USA and one in Prayon in Belgium. All three utilize the same solvant, i.e. the Depa-Topo mixture. The Prayon plant was started up in May 1980. Phosphoric acid is desaturated before the extraction for a long time at a low temperature, totally free from mineral and organic solids and rid of its soluble humic matter until a clear acid of very low optical density is obtained. During the re-extraction of the first cycle, the reduction of U 6+ into U 4+ is effected by metallic iron, according to an original patented process which permits the reduction of the introduced iron to a strict minimum. At the end of the second cycle, an original technique permits the precipitation of a uranium and ammonium hydroxide, starting from the aqueous phase, first separated from the organic phase and purified as regards iron; because of this, the concentrate requires no roasting [fr

  7. Determination of Water Vapor Pressure Over Corrosive Chemicals Versus Temperature Using Raman Spectroscopy as Exemplified with 85.5% Phosphoric Acid

    DEFF Research Database (Denmark)

    Rodier, Marion; Li, Qingfeng; Berg, Rolf W.

    2016-01-01

    with a reference gas (either hydrogen or methane) at a known pressure (typically ∼0.5 bar). By comparing the Raman signals from the water vapor and the references, the water pressure was determined as a function of temperature. A considerable amount of data on the vapor pressure of phosphoric acid are available...... in the literature, to which our results could successfully be compared. A record value of the vapor pressure, 3.40 bar, was determined at 210 ℃. The method required a determination of the precise Raman scattering ratios between the substance, water, and the used reference gas, hydrogen or methane. In our case......A method to determine the water vapor pressure over a corrosive substance was developed and tested with 85.5 ± 0.4% phosphoric acid. The water vapor pressure was obtained at a range of temperatures from ∼25 ℃ to ∼200 ℃ using Raman spectrometry. The acid was placed in an ampoule and sealed...

  8. Learning About Acid Rain: A Teacher's Guide for Grades 6 through 8

    Science.gov (United States)

    Find on this page a link to the Acid Rain Teacher's Guide for Students Grades 6-8. This guide contains information, class discussions and experiments teachers can use to teach students about acid rain.

  9. Radiological assessment occupational radionuclides in a phosphoric acid plant; Evaluacion radiologica ocupacional y distribucion de radionucleidos en una planta de acido fosforico

    Energy Technology Data Exchange (ETDEWEB)

    Bolivar, J. P.; Garcia-Tenorio, R.

    2008-07-01

    On the frame of a research project devoted to the control of the exposure due to natural radiation in several NORM industries located at the South of Spain, a detailed to the production of phosphoric acid has been performed. In addition, the behaviour along the mentioned process of the different radionuclides involved has been analysed. It has been concluded that the effective dose which can be received by the workers of the plant is clearly below 1 mSv/year. And it has been demonstrated that the main route of occupational exposure corresponds to the external radiation due mainly to the permanent presence of a radioactive contamination source in different zones of the plant. This contamination source is associated to the presence of scales in the inner surfaces of pipes and equipment as well as to the presence of sludges in the phosphoric acid storage tanks, which in both cases contain elevated concentrations of 226{sup R}a. Moreover, the 222{sup R}n concentrations inside the plant do not overpass 100 Bq/m{sup 3}, which not constitutes a radiological problem. (Author) 9 refs.

  10. The sealing of second mandibular temporary molar pits and fissure with the laser of Nd: YAG, phosphoric acid and the glass ionomer cement

    International Nuclear Information System (INIS)

    Toda, Maria Aparecida

    2003-01-01

    The main of our study was to check the sealing of second mandibular temporary molar pits and fissure, in vitro, with the laser of Nd: YAG, phosphoric acid at 37% and the glass ionomer cement (CIV, Fuji IX GC).The proposal was to check the structural morphologic changes in the laser irradiation upon the enamel surface to watch the pits and fissure sealing with the glass ionomer cement use after the laser irradiation and to verify the efficiency of the 'double conditioning' (phosphoric acid + Nd: YAG). At the same time we watch the evolution of the temperature in the pulp chamber's inside. Our desire was to achieve a therapeutic alternative technic to prevent the dental caries. The Nd: YAG laser parameters were the same: 79 mJ of energy per pulse; frequency of 5 Hz; mean power of 0,4 W; optical fiber on contact of 320 μm diameter; fluency of 99,52 J/ cm 2 , assuming that the only differential was the time of the laser application on the enamel surface. The samples were prepared with this way: Laser Nd: YAG (53 second) + acid + CIV (Fuji IX); Laser Nd: YAG (53 s); Laser Nd: YAG (20 s + 20 s) + acid + CIV; Laser Nd: YAG (20 s + 20 s); Acid + CIV; Control. Through the scanning electron microscopy (MEV) we noticed fusion and resolidification regions due to the laser irradiation and a better adaptation of the glass ionomer cement when we did the 'double conditioning'. Concerning the temperature increase we can conclude that the echeloned period was the best recommended because the temperature was found in a pattern that would not cause any damage to the dental pulp. For future studies we suggest a longer relaxing time between the laser irradiation, a comparative study of this method with other lasers, the use of other sealing materials and the study with the permanent teeth. (author)

  11. Acid Rain. Activities for Grades 4 to 12. A Teacher's Guide.

    Science.gov (United States)

    Wood, David; Bryant, Jeannette

    This teacher's guide on acid rain is divided into three study areas to explain: (1) what causes acid rain; (2) what problems acid rain has created; and (3) what teachers and students can do to help combat acid rain. Instructions for activities within the study areas include suggested grade levels, objectives, materials needed, and directions for…

  12. Solvent Extraction of Rare Earth Elements from a Nitric Acid Leach Solution of Apatite by Mixtures of Tributyl Phosphate and Di-(2-ethylhexyl) Phosphoric Acid

    Science.gov (United States)

    Ferdowsi, Ali; Yoozbashizadeh, Hossein

    2017-12-01

    Solvent extraction of rare earths from nitrate leach liquor of apatite using mixtures of tributyl phosphate (TBP) and di-(2-ethylhexyl) phosphoric acid (D2EHPA) was studied. The effects of nitrate and hydrogen ion concentration of the aqueous phase as well as the composition and concentration of extractants in the organic phase on the extraction behavior of lanthanum, cerium, neodymium, and yttrium were investigated. The distribution ratio of REEs increases by increasing the nitrate concentration in aqueous phase and concentration of extractants in organic phase, but the hydrogen ion concentration in aqueous phase has a decreasing effect. Yttrium as a heavy rare earth is more sensitive to these parameters than light rare earth elements. Although the composition of organic phase has a minor effect on the extraction of light rare earths, the percent of extraction of yttrium decreases dramatically by increasing the TBP content of organic phase. Mixtures of TBP and D2EHPA can show either synergism or antagonism extraction depending on the concentration and composition of extractants in organic phase. The best condition for separating rare earth elements in groups of heavy and light REEs can be achieved at high nitrate concentration, low H+ concentration, and high concentration of D2EHPA in organic phase. Separation of Ce and La by TBP and D2EHPA is practically impossible in the studied conditions; however, low nitrate concentration and high hydrogen ion concentration in aqueous phase and low concentration of extractants in organic phase favor the separation of Nd from other light rare earth elements.

  13. Analysis of the binary mixtures using the reaction between iron(II) and cerium(IV) sulphate in phosphoric acid medium

    International Nuclear Information System (INIS)

    Krishna Murty, N.; Satyanarayana, V.; Rukmini, N.

    1978-01-01

    The reaction between iron(II) and cerium(IV) sulphate in phosphoric acid medium (6-12M) is studied potentiometrically and visually using methylene blue, thionine, azure A, azure B, azure C, toluidine blue, new methylene blue, variamine blue, ferroin, p-ethoxychrysoidine, N-phenylanthranilic acid and barium diphenylamine sulphonate as indicators. This reaction is made use for the analysis of binary mixtures of Fe(II)-Sn(II), Fe(II)-Ti(III), Fe(II)-U(IV), Fe(II)-Mo(V), Fe(II)-Fe(III) with Ce(IV) sulphate and Ce(IV)-U(VI), Ce(IV)-Mo(VI), Ce(IV)-V(V) and Ce(IV)-Cu(II) with iron (II). (author)

  14. In Situ Formed Phosphoric Acid/Phosphosilicate Nanoclusters in the Exceptional Enhancement of Durability of Polybenzimidazole Membrane Fuel Cells at Elevated High Temperatures

    DEFF Research Database (Denmark)

    Zhang, Jin; Aili, David; Bradley, John

    2017-01-01

    Most recently, we developed a phosphotungstic acid impregnated mesoporous silica (PWA-meso-silica) and phosphoric acid doped polybenzimidazole (PA/PBI) composite membrane for use in high temperature fuel cells and achieved exceptional durability under a constant current load of 200 mA cm−2 at 200°C...... for over 2700 h. In this work, the fundamental role of PWA-meso-silica in enhancing the stability of the PA/PBI membrane has been investigated. The microstructure, the PA uptake, swelling ratio, mechanical property and conductivity of PA/PBI/PWA-meso-silica composite membranes depend on the loading of PWA......-meso-silica. The results indicate that the optimum limit of PWA-meso-silica loading in the PA/PBI membranes is 15 wt%. Detaled analysis indicates that the mesoporous structure of the PWA-meso-silica framework disintegrates, forming phosphosilicate phases within the PBI polymeric matrix during fuel cell operation at 200°C...

  15. Practical applications of phosphors

    CERN Document Server

    Yen, William M; Yamamoto, Hajime

    2006-01-01

    Drawn from the second edition of the best-selling Phosphor Handbook, Practical Applications of Phosphors outlines methods for the production of various phosphors and discusses a broad spectrum of applications. Beginning with methods for synthesis and related technologies, the book sets the stage by classifying and then explaining practical phosphors according to usage. It describes the operating principle and structure of phosphor devices and the phosphor characteristics required for a given device, then covers the manufacturing processes and characteristics of phosphors. The book discusses research and development currently under way on phosphors with potential for practical usage and touches briefly on phosphors that have played a historical role, but are no longer of practical use. It provides a comprehensive treatment of applications including lamps and cathode-ray tubes, x-ray and ionizing radiation, and for vacuum fluorescent and field emission displays and covers inorganic and organic electroluminescen...

  16. High Surface Area Tungsten Carbides: Synthesis, Characterization and Catalytic Activity towards the Hydrogen Evolution Reaction in Phosphoric Acid at Elevated Temperatures

    DEFF Research Database (Denmark)

    Tomás García, Antonio Luis; Li, Qingfeng; Jensen, Jens Oluf

    2014-01-01

    Tungsten carbide powders were synthesized as a potential electrocatalyst for the hydrogen evolution reaction in phosphoric acid at elevated temperatures. With ammonium metatungstate as the precursor, two synthetic routes with and without carbon templates were investigated. Through the intermediate...... nitride route and with carbon black as template, the obtained tungsten carbide samples had higher BET area. In 100% H3PO4 at temperatures up to 185°C, the carbide powders showed superior activity towards the hydrogen evolution reaction. A deviation was found in the correlation between the BET area...... and catalytic activity; this was attributed to the presence of excess amorphous carbon in the carbide powder. TEM imaging and TGA-DTA results revealed a better correlation of the activity with the carbide particle size....

  17. Separation of neptunium, plutonium, americium and curium from uranium with di-(2-ethylhexyl)-phosphoric acid (HDEHP) for radiometric and ICP-MS analysis

    International Nuclear Information System (INIS)

    Ramebaeck, H.; Skaalberg, M.

    1998-01-01

    The possibility of using di-(2-ethylhexyl)-phosphoric acid (HDEHP) in solvent extraction for the separation of neptunium, plutonium, americium and curium from large amounts of uranium was studied. Neptunium, plutonium, americium and curium (as well as uranium) were extracted from HNO 3 , whereafter americium and curium were back-extracted with 5M HNO 3 . Thereafter was neptunium back-extracted in 1M HNO 3 containing hydroxylamine hydronitrate. Finally, plutonium was back-extracted in 3M HCl containing Ti(III). The method separates 238 Pu from 241 Am for α-spectroscopy. For ICP-MS analysis, the interferences from 238 U are eliminated: tailing from 238 U, for analysis of 237 Np, and the interference of 238 UH + for analysis of 239 Pu. The method has been used for the analysis of actinides in samples from a spent nuclear fuel leaching and radionuclide transport experiment. (author)

  18. Investigation of the synergistic effect of alcoholic compounds on the extraction of H3PO4 from Syrian wet phosphoric acid by TBP

    International Nuclear Information System (INIS)

    Abdulbaki, M. K.; Shino, O.; Wahoud, A.

    2006-01-01

    This paper studies the synergistic effects of alcoholic compounds such as isoamyl alcohol. Pentanol, hexanol and heptanol on the extraction of H 3 PO 4 from Syrian phosphoric acid by (TBP). The possibility to use these alcoholic compounds as a diluent instead of kerosene was also studied. The results show that the alcoholic compounds has bigger extraction yield than (TBP) diluted in kerosene. The alcoholic compounds has an important synergistic effect, when it was used as a diluent instead of kerosene, on the extraction of H 3 PO 4 by (TBP) and they have a bigger extraction yield and the quicker phase separation comparing with kerosene. Extraction of uranium, fluoride, sulfate and heavy metals is relatively small. (Authors)

  19. Hydrogen Oxidation on Gas Diffusion Electrodes for Phosphoric Acid Fuel Cells in the Presence of Carbon Monoxide and Oxygen

    DEFF Research Database (Denmark)

    Gang, Xiao; Li, Qingfeng; Hjuler, Hans Aage

    1995-01-01

    Hydrogen oxidation has been studied on a carbon-supported platinum gas diffusion electrode in a phosphoric acidelectrolyte in the presence of carbon monoxide and oxygen in the feed gas. The poisoning effect of carbon monoxide presentin the feed gas was measured in the temperature range from 80...... to 150°C. It was found that throughout the temperaturerange, the potential loss due to the CO poisoning can be reduced to a great extent by the injection of small amounts ofgaseous oxygen into the hydrogen gas containing carbon monoxide. By adding 5 volume percent (v/o) oxygen, an almost......CO-free performance can be obtained for carbon monoxide concentrations up to 0.5 v/o CO at 130°C, 0.2 v/o CO at 100°C,and 0.1 v/o CO at 80°C, respectively....

  20. Shear Bond Strength of an Etch-and-rinse Adhesive to Er:YAG Laser- and/or Phosphoric Acid-treated Dentin

    Directory of Open Access Journals (Sweden)

    Abdolrahim Davari

    2013-06-01

    Full Text Available Background and aims. Er:YAG laser irradiation has been claimed to improve the adhesive properties of dentin; therefore, it has been proposed as an alternative to acid etching. The aim of this in vitro study was to investigate the shear bond strength of an etch-and-rinse adhesive system to dentin surfaces following Er:YAG laser and/or phosphoric acid etching. Materials and methods. The roots of 75 sound maxillary premolars were sectioned below the CEJ and the crowns were embedded in auto-polymerizing acrylic resin with the buccal surfaces facing up. The buccal surfaces were ground using a diamond bur and polished until the dentin was exposed; the samples were randomly divided into five groups (n=15 according to the surface treatment: (1 acid etching; (2 laser etching; (3 laser etching followed by acid etching; (4 acid etching followed by laser etching and (5 no acid etching and no laser etching (control group. Composite resin rods (Point 4, Kerr Co were bonded to treated dentin surfaces with an etch-and-rise adhesive system (Optibond FL, Kerr Co and light-cured. After storage for two weeks at 37°C and 100% humidity and then thermocycling, bond strength was measured with a Zwick Universal Testing Machine at a crosshead speed of 1 mm/min. Data was analyzed using parametric and non-parametric tests (P<0.05. Results. Mean shear bond strength for acid etching (20.1±1.8 MPa and acid+laser (15.6±3.5 MPa groups were significantly higher than those for laser+acid (15.6±3.5 MPa, laser etching (14.1±3.4 MPa and control (8.1±2.1 MPa groups. However, there were no significant differences between acid etching and acid+laser groups, and between laser+acid and laser groups. Conclusion. When the cavity is prepared by bur, it is not necessary to etch the dentin surface by Er:YAG laser following acid etching and acid etching after laser etching.

  1. Distribution equilibria of Eu(III) in the system: bis(2-ethylhexyl)phosphoric acid organic diluent-NaCl, lactic acid, polyaminocarboxylic acid, water

    International Nuclear Information System (INIS)

    Danesi, P.R.; Cianetti, C.; Horwitz, E.P.

    1982-01-01

    The distribution equilibria of Eu 3+ between aqueous phases containing lactic acid and N'-(2hydroxyethyl)ethylenediamine-N,N,N'-triacetic acid (HEDTA) or diethylenetriamine-N,N,N',N',N''-penetaacetic acid (DTPA) at constant ionic strength (μ = 1.0), and n-dodecane solutions of HDEHP have been studied. The formation constants of the simple Eu-lactate complexes and Eu-lactate-HEDTA mixed complex were evaluated from the k/sub d/ data. The conclusion is reached that no lactic acid is coextracted into the organic phase at tracer metal concentrations. The separation factors between Eu 3+ , Pm 3+ , and Am 3+ have been evaluated in the presence of HEDTA

  2. Complexability of o-bisguanidinobenzenes with arsenic and phosphoric acids in solution and solid states, and the potential use of their immobilized derivatives as solid base ligands for metal salts and arsenic acid.

    Science.gov (United States)

    Ito, Tomoya; Suda, Koji; Kumamoto, Takuya; Nakanishi, Waka; Watanabe, Toshiko; Ishikawa, Tsutomu; Seki, Hiroko; Kawahata, Masatoshi; Yamaguchi, Kentaro; Ogura, Yasumitsu; Suzuki, Kazuo T

    2010-02-01

    The role of o-bisguanidinobenzenes (BGBs) as new Brønsted base ligands for arsenic and phosphoric acids was examined. In solution state, complexation was evaluated by Job's plot in (1)H NMR experiment, indicating a 1:1 complex formation, whereas in solid state crystalline structures of complexes obtained were addressed by X-ray crystallographic analysis and/or solid state (13)C NMR experiment, in which 1:2 complexes between the BGB and the acid components were normally formed. Based on these results, Merrifield and Hypogel resin-anchored BGBs were designed and prepared as the corresponding polymer-supported host ligands. Evaluation of their coordination ability with metal salts (ZnCl(2) and CoCl(2)) and arsenic acid in aqueous media by ICP-MS showed that the latter Hypogel resin-anchored BGBs acted as effective immobilized base ligands.

  3. Investigation of heterogeneous solid acid catalyst performance on low grade feedstocks for biodiesel production: A review

    International Nuclear Information System (INIS)

    Mansir, Nasar; Taufiq-Yap, Yun Hin; Rashid, Umer; Lokman, Ibrahim M.

    2017-01-01

    Highlights: • Solid acid catalysts are proficient to esterifying high free fatty acid feedstocks to biodiesel. • Heterogeneous catalysts have the advantage of easy separation and reusability. • Heterogeneous basic catalysts have limitations due to high FFA of low cost feedstocks. • Solid catalysts having acid and base sites reveal better catalyst for biodiesel production. - Abstract: The conventional fossil fuel reserves are continually declining worldwide and therefore posing greater challenges to the future of the energy sources. Biofuel alternatives were found promising to replace the diminishing fossil fuels. However, conversion of edible vegetable oils to biodiesel using homogeneous acids and base catalysts is now considered as indefensible for the future particularly due to food versus fuel competition and other environmental problems related to catalyst system and feedstock. This review has discussed the progression in research and growth related to heterogeneous catalysts used for biodiesel production for low grade feedstocks. The heterogeneous base catalysts have revealed effective way to produce biodiesel, but it has the limitation of being sensitive to high free fatty acid (FFA) or low grade feedstocks. Alternatively, solid acid catalysts are capable of converting the low grade feedstocks to biodiesel in the presence of active acid sites. The paper presents a comprehensive review towards the investigation of solid acid catalyst performance on low grade feedstock, their category, properties, advantages, limitations and possible remedy to their drawbacks for biodiesel production.

  4. Measuring the Confidence of 8th Grade Taiwanese Students' Knowledge of Acids and Bases

    Science.gov (United States)

    Jack, Brady Michael; Liu, Chia-Ju; Chiu, Houn-Lin; Tsai, Chun-Yen

    2012-01-01

    The present study investigated whether gender differences were present on the confidence judgments made by 8th grade Taiwanese students on the accuracy of their responses to acid-base test items. A total of 147 (76 male, 71 female) students provided item-specific confidence judgments during a test of their knowledge of acids and bases. Using the…

  5. Thai Grade 11 Students' Alternative Conceptions for Acid-Base Chemistry

    Science.gov (United States)

    Artdej, Romklao; Ratanaroutai, Thasaneeya; Coll, Richard Kevin; Thongpanchang, Tienthong

    2010-01-01

    This study involved the development of a two-tier diagnostic instrument to assess Thai high school students' understanding of acid-base chemistry. The acid-base diagnostic test (ABDT) comprising 18 items was administered to 55 Grade 11 students in a science and mathematics programme during the second semester of the 2008 academic year. Analysis of…

  6. Fundamentals of phosphors

    CERN Document Server

    Yen, William M; Yamamoto, Hajime

    2006-01-01

    Drawing from the second edition of the best-selling Handbook of Phosphors, Fundamentals of Phosphors covers the principles and mechanisms of luminescence in detail and surveys the primary phosphor materials as well as their optical properties. The book addresses cutting-edge developments in phosphor science and technology including oxynitride phosphors and the impact of lanthanide level location on phosphor performance.Beginning with an explanation of the physics underlying luminescence mechanisms in solids, the book goes on to interpret various luminescence phenomena in inorganic and organic materials. This includes the interpretation of the luminescence of recently developed low-dimensional systems, such as quantum wells and dots. The book also discusses the excitation mechanisms by cathode-ray and ionizing radiation and by electric fields to produce electroluminescence. The book classifies phosphor materials according to the type of luminescence centers employed or the class of host materials used and inte...

  7. Solid-phase extraction of phosphorous-containing amino acid herbicides from biological specimens with a zirconia-coated silica cartridge.

    Science.gov (United States)

    Watanabe, Daisuke; Ohta, Hikoto; Yamamuro, Tadashi

    2014-10-15

    We report a rapid solid-phase extraction method for glyphosate (Glyp), glufosinate (Gluf), and bialaphos (Bial) using a zirconia-coated silica cartridge, which interacts specifically with phosphorous-containing amino acid herbicides (PAAHs). We extracted PAAHs from serum and urine samples. The PAAHs were derivatized with trimethyl orthoacetate-acetic acid and analyzed by ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS). The intra-day and inter-day accuracy was within ±13% RE, the intra-day and inter-day precision was less than 12% RSD, and the total recovery was more than 60% for Glyp and more than 80% for Gluf and Bial. The linearity ranges of the calibration curves of the serum samples were 0.2-10,000μg/mL for Glyp, 0.1-1000μg/L for Gluf, and 0.5-1000μg/L for Bial; and those of the urine samples were 0.4-20,000μg/L for Glyp, 0.2-2000μg/L for Gluf, and 0.1-2000μg/L for Bial. This range covers almost all the reported poisoning cases involving these compounds, from very mild to fatal cases. The present paper offers a universal cleanup method for PAAHs in serum and urine samples for clinical and forensic analysis. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Textural And Mineralogical Studies Of Two Tunisian Sedimentary Phosphates Or Carbonated Fluorapatite Used In The Process Of Production Of Phosphoric Acid

    Directory of Open Access Journals (Sweden)

    Ahmed Chaabouni

    2015-08-01

    Full Text Available Tunisian phosphate is a sedimentary rock and is the second major expense in producing phosphoric acid which is used mainly in fertilizer field. Phosphate is a mesoporous solid and has very large specific surface areas which often lead to greater activity due to increased dispersion of the active sites. The reaction between phosphate rocks and acids is essentially a surface reaction. Within the framework of valorization of Tunisian natural phosphate which is a carbonate fluorapatite or francolite and to establish the relations between the reactivity of phosphate rock and their physico-chemical properties.Two Tunisians deposits of phosphate were selected. Several techniques were used such as the SEM physisorption for textural study X-ray diffraction technique and Infra Red Spectroscopy for the mineralogical study. From the textural study we note that the two samples of phosphate have a mesoporous texture and all phosphate rocks contain many impurities. From the mineralogical study we note that the two main constituents of sedimentary phosphate rocks are apatite and calcium carbonate. The results obtained show a slight difference in physico-chemical properties between the two types of sedimentary phosphates and the dependence between the chemical reactivity and the structure of these phosphates.

  9. Phosphor scintillator structure

    International Nuclear Information System (INIS)

    Cusano, D.A.; Prener, J.S.

    1980-01-01

    A method of fabricating scintillators is described in which the phosphor is distributed within the structure in such a way as to enhance the escape of the visible wavelength radiation that would otherwise be dissipated within the scintillator body. Two embodiments of the present invention are disclosed: one in which the phosphor is distributed in a layered structure and another in which the phosphor is dispersed throughout a transparent matrix. (U.K.)

  10. Numerical analysis of the influence of the impregnation ratio on the microporous structure formation of activated carbons, prepared by chemical activation of waste biomass with phosphoric(V) acid

    Science.gov (United States)

    Kwiatkowski, Mirosław; Kalderis, Dimitrios; Diamadopoulos, Evan

    2017-06-01

    This paper presents the results of the application of new mathematical adsorption models with the unique numerical fast multivariate identification procedure as the tool for analysing the influence of the impregnation ratio i.e. activator to the raw material mass ratio on the microporous structure development of the activated carbons, obtained from sugarcane bagasse and rice husk by chemical activation with phosphoric(V) acid.

  11. Some thiazine dyes as redox indicators in the estimations of U(VI), Mo(VI), V(V), Cr(VI) and Cu(II) with Fe(II) in strong phosphoric acid medium

    International Nuclear Information System (INIS)

    Krishna Murty, N.; Satyanarayana, V.

    1977-01-01

    U(VI) and Mo(VI) in 11.5-12.5M, Cr(VI) in 8.5 10.3M and V(V) and V(IV) in 10.5 12.0M phosphoric acid medium can be estimated with Fe(II) visually using azure A, azure B, azure C, toluidine blue and new methylene blue. (author)

  12. Extractive separation of Al(III) and Ni(II) by Di-2-Ethylhexyl phosphoric acid-kerosene system from aqueous fluoride medium

    International Nuclear Information System (INIS)

    Islam, M.F.; Begum, D.A.; Rahman, M.; Rahman, M.S.

    2009-01-01

    In the study of the extractive separation of Al(III) and Ni(II) by di-2-ethylhexyl phosphoric acid D2EHPA-kerosene from aqueous fluoride medium, about 94% Al(III) and 2% Ni(II) were extracted with 0.3 M D2EHPA (pH 2.1 and temperature 30+-1 degree C). Extraction of Ni(II) decreased with increasing extractant concentration. D2EHPA-kerosene-fluoride system showed better extraction of Al(III) with higher extractant concentration and aqueous pH and vice versa for the extraction of Ni(II). The maximum separation factor (beta 1380) was obtained for Al(III) at 20 degree C and decreased to (beta 732) at 60 degree C. The separation of Al(III) from Ni(II) was favoured at normal temperature. Extraction followed the order Al(III), Ni(II). About 99% stripping of Al(III) was attained from the loaded 0.20 M D2EHPA. Much faster extraction of Al(III) compared to Ni(II) and preferential loading were shown by D2EHPA-kerosene in the presence of fluoride ion in the aqueous phase. Separation of Al(III) was the most outstanding from Ni-Al-F-complex solution. (author)

  13. Investigation of electrolyte leaching in the performance degradation of phosphoric acid-doped polybenzimidazole membrane-based high temperature fuel cells

    Science.gov (United States)

    Jeong, Yeon Hun; Oh, Kyeongmin; Ahn, Sungha; Kim, Na Young; Byeon, Ayeong; Park, Hee-Young; Lee, So Young; Park, Hyun S.; Yoo, Sung Jong; Jang, Jong Hyun; Kim, Hyoung-Juhn; Ju, Hyunchul; Kim, Jin Young

    2017-09-01

    Precise monitoring of electrolyte leaching in high-temperature polymer electrolyte membrane fuel cell (HT-PEMFC) devices during lifetime tests is helpful in making a diagnosis of their quality changes and analyzing their electrochemical performance degradation. Here, we investigate electrolyte leaching in the performance degradation of phosphoric acid (PA)-doped polybenzimidazole (PBI) membrane-based HT-PEMFCs. We first perform quantitative analyses to measure PA leakage during cell operation by spectrophotometric means, and a higher PA leakage rate is detected when the current density is elevated in the cell. Second, long-term degradation tests under various current densities of the cells and electrochemical impedance spectroscopy (EIS) analysis are performed to examine the influence of PA loss on the membrane and electrodes during cell performance degradation. The combined results indicate that PA leakage affect cell performance durability, mostly due to an increase in charge transfer resistance and a decrease in the electrochemical surface area (ECSA) of the electrodes. Additionally, a three-dimensional (3-D) HT-PEMFC model is applied to a real-scale experimental cell, and is successfully validated against the polarization curves measured during various long-term experiments. The simulation results highlight that the PA loss from the cathode catalyst layer (CL) is a significant contributor to overall performance degradation.

  14. Ethanol production from glucose and xylose obtained from steam exploded water-extracted olive tree pruning using phosphoric acid as catalyst.

    Science.gov (United States)

    Negro, M J; Alvarez, C; Ballesteros, I; Romero, I; Ballesteros, M; Castro, E; Manzanares, P; Moya, M; Oliva, J M

    2014-02-01

    In this work, the effect of phosphoric acid (1% w/w) in steam explosion pretreatment of water extracted olive tree pruning at 175°C and 195°C was evaluated. The objective is to produce ethanol from all sugars (mainly glucose and xylose) contained in the pretreated material. The water insoluble fraction obtained after pretreatment was used as substrate in a simultaneous saccharification and fermentation (SSF) process by a commercial strain of Saccharomyces cerevisiae. The liquid fraction, containing mainly xylose, was detoxified by alkali and ion-exchange resin and then fermented by the xylose fermenting yeast Scheffersomyces stipitis. Ethanol yields reached in a SSF process were close to 80% when using 15% (w/w) substrate consistency and about 70% of theoretical when using prehydrolysates detoxified by ion-exchange resins. Considering sugars recovery and ethanol yields about 160g of ethanol from kg of water extracted olive tree pruning could be obtained. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Effect of a self-etching primer and phosphoric acid etching on the bond strength of 4-META/MMA-TBB resin to human enamel.

    Science.gov (United States)

    Nogawa, Hiroshi; Koizumi, Hiroyasu; Saiki, Osamu; Hiraba, Haruto; Nakamura, Mitsuo; Matsumura, Hideo

    2015-01-01

    The purpose of this study was to evaluate the shear bond strength and durability of 4-META/MMA-TBB resin to human enamel. A self-etching primer that contained 4-META (Teeth Primer, TP) and 35-45% or 60-65% concentrations of phosphoric acid (K-Etchant Gel, KE, and Super Bond C&B Red Activator, RA) were used as the surface treatment agents. A methyl methacrylate (MMA)-based self-polymerizing resin (Super-Bond C&B) was used as a luting agent. The shear bond strength was determined both pre and post thermocycling. The results were statistically analyzed with a non-parametric procedure. The post-thermocycling shear bond strength of the TP group was significantly higher than that of other groups, and that of the KE group was significantly higher compared with the RA group. These results demonstrated that 4-META was effective. Furthermore, when the degree of tooth demineralization was compared, surface treatment with less demineralization using TP was the most effective treatment.

  16. Features of the Thermodynamics of Trivalent Lanthanide/Actinide Distribution Reactions by Tri-n-Octylphosphine Oxide and Bis(2-EthylHexyl) Phosphoric Acid

    Energy Technology Data Exchange (ETDEWEB)

    Travis S. Grimes; Peter R. Zalupski

    2014-11-01

    A new methodology has been developed to study the thermochemical features of the biphasic transfer reactions of trisnitrato complexes of lanthanides and americium by a mono-functional solvating ligand (tri-n-octyl phosphine oxide - TOPO). Stability constants for successive nitrato complexes (M(NO3)x3-x (aq) where M is Eu3+, Am3+ or Cm3+) were determined to assist in the calculation of the extraction constant, Kex, for the metal ions under study. Enthalpies of extraction (?Hextr) for the lanthanide series (excluding Pm3+) and Am3+ by TOPO have been measured using isothermal titration calorimetry. The observed ?Hextr were found to be constant at ~29 kJ mol-1across the series from La3+-Er3+, with a slight decrease observed from Tm3+-Lu3+. These heats were found to be consistent with enthalpies determined using van ’t Hoff analysis of temperature dependent extraction studies. A complete set of thermodynamic parameters (?G, ?H, ?S) was calculated for Eu(NO3)3, Am(NO3)3 and Cm(NO3)3 extraction by TOPO and Am3+ and Cm3+ extraction by bis(2-ethylhexyl) phosphoric acid (HDEHP). A discussion comparing the energetics of these systems is offered. The measured biphasic extraction heats for the transplutonium elements, ?Hextr, presented in these studies are the first ever direct measurements offered using two-phase calorimetric techniques.

  17. Facilitated transport of Cr(III) through activated composite membrane containing di-(2-ethylhexyl)phosphoric acid (DEHPA) as carrier agent.

    Science.gov (United States)

    Arslan, Gulsin; Tor, Ali; Cengeloglu, Yunus; Ersoz, Mustafa

    2009-06-15

    The facilitated transport of chromium(III) through activated composite membrane (ACM) containing di-(2-ethylhexyl) phosphoric acid (DEHPA) was investigated. DEHPA was immobilised by interfacial polymerisation on polysulfone layer which was deposited on non-woven fabric by using spin coater. Then, ACM was characterised by using scanning electron microscopy (SEM), contact angle measurements and atomic force microscopy (AFM). Initially, batch experiments of liquid-liquid distribution of Cr(III) and the extractant (DEHPA) were carried out to determine the appropriate pH of the feed phase and the results showed that maximum extraction of Cr(III) was achieved at a pH of 4. It was also found that Cr(III) and DEHPA reacted in 1/1 molar ratio. The effects of Cr(III) (in feed phase), HCl (in stripping phase) and DEHPA (in ACM) concentrations were investigated. DEHPA concentration varies from 0.1 to 1.0M and it was determined that the transport of Cr(III) increased with the carrier concentration up to 0.8M. It was also observed that the transport of Cr(III) through the ACM tended to increase with Cr(III) and HCl concentrations. The stability of ACM was also confirmed with replicate experiments.

  18. Liquid–liquid equilibria study of the (water + phosphoric acid + hexyl or cyclohexyl acetate) systems at T = (298.15, 308.15, and 318.15) K: Measurement and thermodynamic modelling

    International Nuclear Information System (INIS)

    Ghanadzadeh Gilani, A.; Ghanadzadeh Gilani, H.; Shekarsaraee, S.; Nasiri-Touli, E.; Seyed Saadat, S.L.

    2016-01-01

    Highlights: • Tie line data for aqueous solutions of phosphoric acid with esters were obtained. • The LLE data were correlated using the UNIQUAC and NRTL models. • The quality of the LLE data was validated using the appropriate equations. • Separation factors were calculated for the chosen solvents. - Abstract: Liquid–liquid equilibrium (LLE) data for the (water + phosphoric acid + n-hexyl acetate or cyclohexyl acetate) ternary systems were determined at T = (298.15, 308.15 and 318.15) K and p = 101.3 kPa. The cloud point method was used to obtain the solubility and the Karl-Fischer, acidimetric titration, and refractive index methods were used to determine the tie-line values. Both the ternary systems exhibit type-1 behavior of LLE. The experimental values were regressed and acceptably correlated using the UNIQUAC and NRTL models. The reliability of the experimental tie lines was confirmed using the Othmer–Tobias plot. Experimental distribution coefficients and separation factors were fitted using the Kamlet–Taft LSER model. The influence of temperature on the biphasic area and separation factor was found to be minor. As a result, both the esters are suitable separating agents for aqueous phosphoric acid mixtures.

  19. Esterification of Free Fatty Acid in Crude Palm Oil Off Grade

    Directory of Open Access Journals (Sweden)

    Muhammad Dani Supardan

    2009-12-01

    Full Text Available The esterification of free fatty acids (FFA found in crude palm oil (CPO off grade with methanol is a promising technique to convert FFA into valuable fatty acid methyl ester (FAME, biodiesel and obtain a FFA-free oil that can be further transesterified using alkali bases. In this work, the effects of the main variables involved in the esterification process i.e. alcohol to oil molar ratio, reaction temperature, agitation speed and the initial amount of FFA of oil, were studied in the presence of sulphuric acid as catalyst at concentration of 1%-w. The experimental results show that the esterification process could lead to a practical and cost effective FFA removal unit in front of typical oil transesterification for biodiesel production. Keywords: CPO off grade, esterification, free fatty acid

  20. The effect of phosphoric acid concentration on the synthesis of nano-whiskers of calcium metaphosphate by chemical precipitation Method

    Science.gov (United States)

    Yao, Nengjian; Zhang, Yin; Kong, Deshuang; Zhu, Jianping; Tao, Yaqiu; Qiu, Tai

    2011-10-01

    Calcium metaphosphate (CMP) nano-whiskers were produced by a chemical precipitation method. In order to produce nano-powders, CMP was prepared by the mixing of two precursors, calcium oxide (CaO) and phosphate acid (H3PO4). Sparingly soluble chemicals, the Ca/P ratio of the mixture was set to be 0.50 to produce stoichiometric CMP, were chemical agitated in phosphate acid solution. At least 3 hours of pre-hydrolysis of phosphorus precursor were required to obtain CMP phase. The CMP powders were dried in a drying oven at 60 °C for 7 days and then followed by a heat treatment at 390 °C for 8hours. The obtained powder was analyzed using XRD, XRF, FT-IR, SEM, TG-DTA, Zeta Potential Meter, Specific Surface Area, and Particle Size Analyzer. The results showed that obtained CMP nano-whiskers have a significantly powder characteristics.

  1. Modeling the hydrolysis of perfluorinated compounds containing carboxylic and phosphoric acid ester functions, alkyl iodides, and sulfonamide groups

    OpenAIRE

    Sierra Rayne; Kaya Forest

    2009-01-01

    Temperature dependent rate constants were estimated for the acid- and base-catalyzed and neutral hydrolysis reactions of perfluorinated telomer acrylates (FTAcrs) and phosphate esters (FTPEs), and the SN1 and SN2 hydrolysis reactions of fluorotelomer iodides (FTIs). Under some environmental conditions, hydrolysis of monomeric FTAcrs could be rapid (half-lives of several years in marine systems and as low as several days in some landfills) and represent a dominant portion of their overall degr...

  2. The Association of Fatty Acid Levels and Gleason Grade among Men Undergoing Radical Prostatectomy.

    Directory of Open Access Journals (Sweden)

    Zhiguo Zhao

    Full Text Available Epidemiological data suggest that omega-6 (ω-6 fatty acids (FAs may be associated with cancer incidence and/or cancer mortality, whereas ω-3 FAs are potentially protective. We examined the association of the ratio of ω-6 to ω-3 FA (ω-6:ω-3 and individual FA components with pathological results among men with prostate cancer (PCa undergoing radical prostatectomy.Sixty-nine men were included in the study. Components of ω-6 (linoleic acid (LA, arachidonic acid (AA, and dihomo-γ-linolenic acid (DGLA and ω-3 (docosahexaenoic acid (DHA and eicosapentaenoic acid (EPA were analyzed by liquid chromatography/mass selective detector separation. Logistic regression analysis was performed to determine association of FA with pathological high grade (Gleason ≥4+3 disease.The were 35 men with low grade disease (Gleason ≤3+4 and 34 men with high grade disease. Men with low grade disease were significantly younger (58y vs 61y, p = 0.012 and had lower D'Amico clinical classification (p = 0.001 compared to men with high grade disease. There was no significant association of ω-6:ω-3 with high grade disease (OR 0.93, p = 0.78, however overall ω-6, ω-3, and individual components of ω-6 and ω-3 FAs except EPA were significantly associated with high grade disease (ω-6: OR 3.37, 95% CI: 1.27,8.98; LA: OR 3.33, 95% CI:1.24,8.94; AA: OR 2.93, 95% CI:1.24,6.94; DGLA: OR 3.21, 95% CI:1.28,8.04; ω-3: OR 3.47, 95% CI:1.22,9.83; DHA: OR 3.13, 95% CI:1.26,7.74. ω-6 and ω-3 FA components were highly correlated (Spearman ρ = 0.77.Higher levels of individual components of ω-6 and ω-3FAs may be associated with higher-grade PCa.Studies into the causative factors/pathways regarding FAs and prostate carcinogenesis may prove a potential association with PCa aggressiveness.

  3. Dilute phosphoric acid-catalysed hydrolysis of municipal bio-waste wood shavings using autoclave parr reactor system.

    Science.gov (United States)

    Orozco, Angela M; Al-Muhtaseb, Ala'a H; Albadarin, Ahmad B; Rooney, David; Walker, Gavin M; Ahmad, Mohammad N M

    2011-10-01

    The visibility of using municipal bio-waste, wood shavings, as a potential feedstock for ethanol production was investigated. Dilute acid hydrolysis of wood shavings with H₃PO₄ was undertaken in autoclave parr reactor. A combined severity factor (CSF) was used to integrate the effects of hydrolysis times, temperature and acid concentration into a single variable. Xylose concentration reached a maximum value of 17 g/100 g dry mass corresponding to a yield of 100% at the best identified conditions of 2.5 wt.% H₃PO₄, 175 °C and 10 min reaction time corresponding to a CSF of 1.9. However, for glucose, an average yield of 30% was obtained at 5 wt.% H₃PO₄, 200 °C and 10 min. Xylose production increased with increasing temperature and acid concentration, but its transformation to the degradation product furfural was also catalysed by those factors. The maximum furfural formed was 3 g/100 g dry mass, corresponding to the 24% yield. Copyright © 2011 Elsevier Ltd. All rights reserved.

  4. Transport of Eu3+ through a Bis(2-ethylhexyl)-phosphoric acid, n-dodecane solid supported liquid membrane

    International Nuclear Information System (INIS)

    Danesi, P.R.; Horwitz, E.P.; Rickert, P.

    1982-01-01

    The coupled transpot of Eu 3 + and H + ions througn a solid supported liquid membrane consisting of a porous polypropylene film immobilizing an HDEHP solution in n-dodecane has been studied as a function of the membrane area, stirring speed of the aqueous solutions, membrane composition, and acidity of the feed solution. The experimental results are in agreement with predictions derived from a theoretical permeability coefficient equation which assumes that membrane diffusion and aqueous film diffusion are the only rate-controlling factors

  5. DISTRIBUTION OF LANTHANIDE AND ACTINIDE ELEMENTS BETWEEN BIS-(2-ETHYLHEXYL)PHOSPHORIC ACID AND BUFFERED LACTATE SOLUTIONS CONTAINING SELECTED COMPLEXANTS

    Energy Technology Data Exchange (ETDEWEB)

    Rudisill, Tracy S.; Diprete, David P.; Thompson, Major C.

    2013-04-15

    With the renewed interest in the closure of the nuclear fuel cycle, the TALSPEAK process is being considered for the separation of Am and Cm from the lanthanide fission products in a next generation reprocessing plant. However, an efficient separation requires tight control of the pH which likely will be difficult to achieve on a large scale. To address this issue, we measured the distribution of lanthanide and actinide elements between aqueous and organic phases in the presence of complexants which were potentially less sensitive to pH control than the diethylenetriaminepentaacetic (DTPA) used in the process. To perform the extractions, a rapid and accurate method was developed for measuring distribution coefficients based on the preparation of lanthanide tracers in the Savannah River National Laboratory neutron activation analysis facility. The complexants tested included aceto-, benzo-, and salicylhydroxamic acids, N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), and ammonium thiocyanate (NH{sub 4}SCN). The hydroxamic acids were the least effective of the complexants tested. The separation factors for TPEN and NH{sub 4}SCN were higher, especially for the heaviest lanthanides in the series; however, no conditions were identified which resulted in separations factors which consistently approached those measured for the use of DTPA.

  6. Characterization and application of expanded graphite modified with phosphoric acid and glucose for the removal of Ni(II) from aqueous solution

    Science.gov (United States)

    Jiang, Li; Zhang, Jian; Xu, Xiaoli; Zhang, Jie; Liu, Hai; Guo, Zizhang; Kang, Yan; Li, Yiran; Xu, Jingtao

    2015-12-01

    Three kinds of modified expanded graphite (EG), impregnated with phosphoric acid (H3PO4) (P-EG), impregnated with glucose (G-EG), and impregnated with H3PO4 and glucose (G-P-EG), were prepared under a low temperature (150 °C). The adsorption capacity of G-P-EG (Qm = 7.016 mg/g) is much higher than original expanded graphite (EG Qm = 0.423 mg/g) and other two kinds of modified expanded graphite (P-EG Qm = 0.770 mg/g; G-EG Qm = 0.507 mg/g). The physicochemical properties of EG and G-P-EG were characterized by N2 adsorption/desorption, Boehm's titration and X-ray photoelectron spectroscopy (XPS). EG exhibited higher values of BET surface area (11.357 m2/g) and total pore volume (0.0303 cm3/g) than that of G-P-EG (4.808 m3/g and 0.0109 cm3/g). However, the results of Bohm's titration and XPS showed that G-P-EG contained more surface oxygen-containing functional groups. The Ni(II) adsorption equilibrium data agreed well with the Langmuir model. And the experimental data of EG and G-P-EG fitted better by pseudo-second order model. Based on the results of batch adsorption experiments and XPS analysis, there were several possible mechanisms for Ni(II) adsorption on the G-P-EG, including chemical adsorption, cation exchange, electrostatic attraction and surface complication.

  7. Molecular and supramolecular speciations of solvent extraction systems based on malonamide and/or dialkyl-phosphoric acids for An(III)/Ln(III)

    International Nuclear Information System (INIS)

    Gannaz, B.

    2006-06-01

    The solvent extraction system used in the DIAMEX-SANEX process, developed for the actinide(III)/lanthanide(III) separation, is based on the use of mixtures of the malonamide DMDOHEMA and a dialkyl-phosphoric acid (HDEHP or HDHP), in hydrogenated tetra-propylene. The complexity of these systems urges on a novel approach to improve the conventional methods (thermodynamics, solvent extraction) which hardly explain the macroscopic behaviors observed (3. phase, over-stoichiometry). This approach combines studies on both supramolecular (VPO, SANS, SAXS) and molecular (liquid-liquid extraction, ESI-MS, IR, EXAFS) speciations of single extractant systems (DMDOHEMA or HDHP in in n-dodecane) and their mixture. In spite of safety constraints due to the handling of radio-material, they were used in the studies as much as possible, like for SAXS measurements on americium-containing samples, a worldwide first-time. In each of the investigated systems, actinides(III) and lanthanides(III) are extracted to the organic phase in polar cores of reversed micelles, the inner and outer-sphere compositions of which are proposed. Thus, the 4f and 5f cations are extracted by reversed micelles such as [(DMDOHEMA) 2 M(NO 3 ) 3 ] inn (DMDOHEMA) x (HNO 3 ) z (H 2 O) w ] out and M(DHP) 3 (HDHP) y-3 (H 2 O) w with y = 3 to 6, for the single extractant systems. In the case of the two extractants system, the less concentrated one acts like a co-surfactant regarding the mixed aggregate formation [(DMDOHEMA) 2 M(NO 3 ) 3-v (DHP) v ] inn [(DMDOFIEMA) x (HDHP) y (HNO 3 )z(H 2 O) w ] out . (author)

  8. Features of the thermodynamics of trivalent lanthanide/actinide distribution reactions by tri-n-octylphosphine oxide and bis(2-ethylhexyl) phosphoric acid.

    Science.gov (United States)

    Grimes, Travis S; Zalupski, Peter R; Martin, Leigh R

    2014-11-06

    A new methodology has been developed to study the thermochemical features of the biphasic transfer reactions of trisnitrato complexes of lanthanides and americium by a monofunctional solvating ligand (tri-n-octylphosphine oxide, TOPO). Stability constants for successive nitrato complexes (M(NO3)x(3-x)(aq) where M is Eu(3+), Am(3+), or Cm(3+)) were determined to assist in the calculation of the extraction constant, K(ex), for the metal ions under study. Enthalpies of extraction (ΔH(extr)) for the lanthanide series (excluding Pm(3+)) and Am(3+) by TOPO have been measured using isothermal titration calorimetry. The observed ΔH(extr) were found to be constant at ~29 kJ mol(-1) across the series from La(3+) to Er(3+), with a slight decrease observed from Tm(3+) to Lu(3+). These heats were found to be consistent with enthalpies determined using van't Hoff analysis of temperature dependent extraction studies. A complete set of thermodynamic parameters (ΔG, ΔH, ΔS) was calculated for Eu(NO3)3, Am(NO3)3, and Cm(NO3)3 extraction by TOPO and Am(3+) and Cm(3+) extraction by bis(2-ethylhexyl) phosphoric acid (HDEHP). A discussion comparing the energetics of these systems is offered. The measured biphasic extraction heats for the transplutonium elements, ΔH(extr), presented in these studies are the first ever direct measurements offered using two-phase calorimetric techniques.

  9. Modelling and Optimization of Corrosion Inhibition of Mild Steel in Phosphoric Acid by Red Pomegranate Peels Aqueous Extract

    Directory of Open Access Journals (Sweden)

    Khalid Hamid Rashid

    2011-11-01

    Full Text Available Taguchi experimental design (TED is applied to find the optimum effectiveness of aqueous Red Pomegranate Peel (RPP extract as a green inhibitor for the corrosion of mild steel in 2M H3PO4 solution. The Taguchi methodology has been used to study the effects of changing, temperature, RPP concentration and contact period, at three levels. Weight-loss measurements were designed by construction a L9 orthogonal arrangement of experiments. Results of the efficiencies of inhibition were embraced for the signal to noise proportion & investigation of variance (ANOVA. The results were further processed with a MINITAB-17 software package to find the optimal conditions for inhibitor usage. Second order polynomial model was used for experimental data fitting. Optimum conditions for achieving the maximum corrosion inhibition efficiency are obtained from optimizing the above model and are found as follow: 39.66 °C temperature of acidic media, 38.29 ml/L inhibitor concentration and 2.95 h contact period. Results demonstrated that rate of corrosion was increased with temperature increasing & decreasing inhibitor concentration. It was concluded that the Taguchi design was adequately useful in the optimization of operating parameters and that RPP sufficiently inhibited the corrosion of steel at the range of variables studied.

  10. Solvent extraction of lanthanoid, yttrium and some polyvalent metal ions with phosphoric acid esters of Triton X-100

    International Nuclear Information System (INIS)

    Yoshida, Isao; Hirasawa, Jun'ichi; Tsumagari, Hiroto; Ueno, Keihei; Takagi, Makoto.

    1986-01-01

    Polyoxyethylene chain-containing nonionic surfactant, Triton X-100 (decaethyleneglycol mono(4-(1,1,3,3-tetramethylbutyl)phenyl) ether; ROH) was derived to phosphate mono-, di-, and tri-esters RH 2 PO 4 , R 2 HPO 4 and R 3 PO 4 ; abbreviated as MTP, DTP and TTP, respectively) and the metal extraction behavior of these phosphate esters was studied in 1,2-dichloroethane-water system with particular emphasis on lanthanoid(III), yttrium(III), and some other polyvalent metal ions. The extraction was carried out at pH 2 in the presence (for TTP) or in the absence (for MTP and DTP) of picric acid. The metal extraction ability of these extractants followed the order of MTP > DTP > TTP under these extraction conditions. In the extraction by MTP and DTP, the extractability of lanthanoid ions increased with the increase in their atomic number. Mean separation factor of thirteen pairs of adjacent lanthanoids was evaluated to be 1.7 for MTP and 1.4 for DTP. On the other hand, the corresponding values for TTP was almost unity. None of these compounds practically extracted other polyvalent metal ions except iron ion. Iron(III) ion was extracted with MTP and with DTP to a similar level to those of lanthanoid ions. (author)

  11. Effect of three organic amendments and of the lime on the readiness and the phosphorous adsorption in an acid soil

    International Nuclear Information System (INIS)

    Gomez L, Carmen Rosa; Narvaez C, Carlos Eduardo

    1999-01-01

    To observe the effects of the organic materials and lime on the availability and sorption of phosphorus in a strongly acid soil (Inceptic Hapludox), poor in P, a greenhouse experiment and a laboratory studied were conducted. Plastic pots were filled with 400 g of soil to which was given a basic N.P.K.S. fertilization with applications of 90 kg P 2 O-5 hectare chicken manure, compost or cowpea (Vigna Unguiculata) were added to soil at the rates of 0.0; 0,8 and 2,4 g O.M. 100 g - 1 separate soil samples were amended with 1,5 ton CaCO 3 hectare. Soils were incubated for periods of 2, 14 and 54 days; after each period, pH, exchangeable AL and available P were determined. In soils incubated 54 days, the P sorption was evaluated trough isotherms and was interrelated the available P with the P sorption. Either, organic materials or lime increased the available P. Chicken manure let levels between 25 and 120 mg P kg - 1 the compost between 12 and 37, the cowpea between 6 and 15 and the lime between 3 and 8 mg P kg - 1. The availability of phosphorus increase with increasing rates of the organics materials but is reduced upon elapsing the incubated period. The treatments decreased drastically exchangeable al and this had relationship to the increase of the available P. The behavior in the P sorption was fitted to freundlich equation. The basic fertilization did not modify the p sorption while the organic amendments and the lime reduced it in different degree. The value of K, in the expression of the isotherms, shows an important reduction of the P sorption capacity in soil, caused by the chicken manure. An inverse relationship was observed between the p available and the value of K

  12. Low lag luminescent phosphors

    International Nuclear Information System (INIS)

    1976-01-01

    The addition of potassium or rubidium salts to europium-activated fluorohalide phosphors produces X-ray screens with low lag, even at very low europium concentrations. The chemical preparation and afterglow test results are described

  13. Phosphor thermometry system

    Science.gov (United States)

    Beshears, David L.; Sitter, Jr., David N.; Andrews, William H.; Simpson, Marc L.; Abston, Ruth A.; Cates, Michael R.; Allison, Steve W.

    2000-01-01

    An apparatus for measuring the temperature of a moving substrate includes an air gun with a powder inlet port in communication with the outlet port of a powder reservoir, an air inlet port in communication with a pressurized air source, and an outlet nozzle spaced from and directed toward the moving substrate. The air gun is activated by the air pulses to spray controlled amounts of the powdered phosphor onto the moving substrate, where the phosphor assumes the temperature of the moving substrate. A laser produces light pulses, and optics direct the light pulses onto the phosphor on the moving substrate, in response to which the phosphor emits a luminescence with a decay rate indicative of the temperature of the phosphor. A collection lens is disposed to focus the luminescence, and a photodetector detects the luminescence focused by the collection lens and produces an electrical signal that is characteristic of the brightness of the luminescence. A processor analyzes the electrical signal to determine the decay characteristic of the luminescence and to determine the temperature of the phosphor from the decay characteristic.

  14. Phosphors for LED lamps

    Science.gov (United States)

    Murphy, James Edward; Manepalli, Satya Kishore; Kumar, Prasanth Nammalwar

    2013-08-13

    A phosphor, a phosphor blend including the phosphor, a phosphor prepared by a process, and a lighting apparatus including the phosphor blend are disclosed. The phosphor has the formula (Ca.sub.1-p-qCe.sub.pK.sub.q).sub.xSc.sub.y(Si.sub.1-rGa.sub.r).sub.zO.su- b.12+.delta. or derived from a process followed using disclosed amounts of reactants. In the formula, (0

  15. High temperature thermometric phosphors

    Science.gov (United States)

    Allison, Stephen W.; Cates, Michael R.; Boatner, Lynn A.; Gillies, George T.

    1999-03-23

    A high temperature phosphor consists essentially of a material having the general formula LuPO.sub.4 :Dy.sub.(x),Eu.sub.y) wherein: 0.1 wt %.ltoreq.x.ltoreq.20 wt % and 0.1 wt %.ltoreq.y.ltoreq.20 wt %. The high temperature phosphor is in contact with an article whose temperature is to be determined. The article having the phosphor in contact with it is placed in the environment for which the temperature of the article is to be determined. The phosphor is excited by a laser causing the phosphor to fluoresce. The emission from the phosphor is optically focused into a beam-splitting mirror which separates the emission into two separate emissions, the emission caused by the dysprosium dopant and the emission caused by the europium dopent. The separated emissions are optically filtered and the intensities of the emission are detected and measured. The ratio of the intensity of each emission is determined and the temperature of the article is calculated from the ratio of the intensities of the separate emissions.

  16. 5-Aminolevulinic Acid Fluorescence in High Grade Glioma Surgery: Surgical Outcome, Intraoperative Findings, and Fluorescence Patterns

    Directory of Open Access Journals (Sweden)

    Alessandro Della Puppa

    2014-01-01

    Full Text Available Background. 5-Aminolevulinic acid (5-ALA fluorescence is a validated technique for resection of high grade gliomas (HGG; the aim of this study was to evaluate the surgical outcome and the intraoperative findings in a consecutive series of patients. Methods. Clinical and surgical data from patients affected by HGG who underwent surgery guided by 5-ALA fluorescence at our Department between June 2011 and February 2014 were retrospectively evaluated. Surgical outcome was evaluated by assessing the resection rate as gross total resection (GTR>98% and GTR>90%. We finally stratified data for recurrent surgery, tumor location, tumor size, and tumor grade (IV versus III grade sec. WHO. Results. 94 patients were finally enrolled. Overall GTR>98% and GTR>90% was achieved in 93% and 100% of patients. Extent of resection (GTR>98% was dependent on tumor location, tumor grade (P<0.05, and tumor size (P<0.05. In 43% of patients the boundaries of fluorescent tissue exceeded those of tumoral tissue detected by neuronavigation, more frequently in larger (57% (P<0.01 and recurrent (60% tumors. Conclusions. 5-ALA fluorescence in HGG surgery enables a GTR in 100% of cases even if selection of patients remains a main bias. Recurrent surgery, and location, size, and tumor grade can predict both the surgical outcome and the intraoperative findings.

  17. Actinide recovery from waste and low-grade sources

    International Nuclear Information System (INIS)

    Navratil, J.D.; Schulz, W.W.

    1982-01-01

    Actinide and nuclear fuel cycle operations generate a variety of process waste streams. New methods are needed to remove and recover actinides. More interest is also being expressed in recovering uranium from oceans, phosphoric acid, and other low grade sources. To meet the need for an up-to-date status report in the area of actinide recovery from waste and low grade sources, these papers were brought together. The papers provide an authoritative, in-depth coverage of an important area of nuclear and industrial and engineering chemistry which cover the following topics: uranium recovery from oceans and phosphoric acid; recovery of actinides from solids and liquid wastes; plutonium scrap recovery technology; and other new developments in actinide recovery processes

  18. Effect of a low-viscosity adhesive resin on the adhesion of metal brackets to enamel etched with hydrochloric or phosphoric acid combined with conventional adhesives.

    Science.gov (United States)

    Yetkiner, Enver; Ozcan, Mutlu; Wegehaupt, Florian Just; Wiegand, Annette; Eden, Ece; Attin, Thomas

    2013-12-01

    This study investigated the effect of a low-viscosity adhesive resin (Icon) applied after either hydrochloric (HCl) or phosphoric acid (H3PO4) on the adhesion of metal brackets to enamel. Failure types were analyzed. The crowns of bovine incisors (N = 20) were sectioned mesio-distally and inciso-gingivally, then randomly assigned to 4 groups according to the following protocols to receive mandibular incisor brackets: 1) H3PO4 (37%)+TransbondXT (3M UNITEK); 2) H3PO4 (37%)+Icon+TransbondXT; 3) HCl (15%)+Icon (DMG)+TransbondXT 4) HCl (15%)+Icon+Heliobond (Ivoclar Vivadent)+TransbondXT. Specimens were stored in distilled water at 37°C for 24 h and thermocycled (5000x, 5°C to 55°C). The shear bond strength (SBS) test was performed using a universal testing machine (1 mm/min). Failure types were classified according to the Adhesive Remnant Index (ARI). Contact angles of adhesive resins were measured (n = 5 per adhesive) on ceramic surfaces. No significant difference in SBS was observed, implying no difference between combinations of adhesive resins and etching agents (p = 0.712; ANOVA). The Weibull distribution presented significantly lower Weibull modulus (m) of group 3 (m = 2.97) compared to other groups (m = 5.2 to 6.6) (p group 1 (45.4 ± 7.9) > group 2 (44.2 ± 10.6) > group 3 (42.6 ± 15.5). While in groups 1, 3, and 4 exclusively an ARI score of 0 (no adhesive left on tooth) was observed, in group 2, only one specimen demonstrated score 1 (less than half of adhesive left on tooth). Contact angle measurements were as follows: Icon (25.86 ± 3.81 degrees), Heliobond (31.98 ± 3.17 degrees), TransbondXT (35 ± 2.21 degrees). Icon can be safely used with the conventional adhesives tested on surfaces etched with either HCl or H3PO4.

  19. Characterization and application of expanded graphite modified with phosphoric acid and glucose for the removal of Ni(II) from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Li [Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan 250100 (China); Zhang, Jian, E-mail: zhangjian00@sdu.edu.cn [Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan 250100 (China); Xu, Xiaoli [Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan 250100 (China); Zhang, Jie [Shandong Experimental High School, Jinan 250100 (China); Liu, Hai; Guo, Zizhang; Kang, Yan; Li, Yiran [Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan 250100 (China); Xu, Jingtao [School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan 250100 (China)

    2015-12-01

    Highlights: • Glucose and H{sub 3}PO{sub 4}, single or together, were used to modify expanded graphite. • The modified condition was at a low temperature (150 °C). • The properties of EG and the highest adsorption ability modified EG were compared. • G-P-EG has the highest adsorption ability, which is much higher than that of EG. - Abstract: Three kinds of modified expanded graphite (EG), impregnated with phosphoric acid (H{sub 3}PO{sub 4}) (P-EG), impregnated with glucose (G-EG), and impregnated with H{sub 3}PO{sub 4} and glucose (G-P-EG), were prepared under a low temperature (150 °C). The adsorption capacity of G-P-EG (Q{sub m} = 7.016 mg/g) is much higher than original expanded graphite (EG Q{sub m} = 0.423 mg/g) and other two kinds of modified expanded graphite (P-EG Q{sub m} = 0.770 mg/g; G-EG Q{sub m} = 0.507 mg/g). The physicochemical properties of EG and G-P-EG were characterized by N{sub 2} adsorption/desorption, Boehm's titration and X-ray photoelectron spectroscopy (XPS). EG exhibited higher values of BET surface area (11.357 m{sup 2}/g) and total pore volume (0.0303 cm{sup 3}/g) than that of G-P-EG (4.808 m{sup 3}/g and 0.0109 cm{sup 3}/g). However, the results of Bohm's titration and XPS showed that G-P-EG contained more surface oxygen-containing functional groups. The Ni(II) adsorption equilibrium data agreed well with the Langmuir model. And the experimental data of EG and G-P-EG fitted better by pseudo-second order model. Based on the results of batch adsorption experiments and XPS analysis, there were several possible mechanisms for Ni(II) adsorption on the G-P-EG, including chemical adsorption, cation exchange, electrostatic attraction and surface complication.

  20. Characterization and application of expanded graphite modified with phosphoric acid and glucose for the removal of Ni(II) from aqueous solution

    International Nuclear Information System (INIS)

    Jiang, Li; Zhang, Jian; Xu, Xiaoli; Zhang, Jie; Liu, Hai; Guo, Zizhang; Kang, Yan; Li, Yiran; Xu, Jingtao

    2015-01-01

    Highlights: • Glucose and H 3 PO 4 , single or together, were used to modify expanded graphite. • The modified condition was at a low temperature (150 °C). • The properties of EG and the highest adsorption ability modified EG were compared. • G-P-EG has the highest adsorption ability, which is much higher than that of EG. - Abstract: Three kinds of modified expanded graphite (EG), impregnated with phosphoric acid (H 3 PO 4 ) (P-EG), impregnated with glucose (G-EG), and impregnated with H 3 PO 4 and glucose (G-P-EG), were prepared under a low temperature (150 °C). The adsorption capacity of G-P-EG (Q m = 7.016 mg/g) is much higher than original expanded graphite (EG Q m = 0.423 mg/g) and other two kinds of modified expanded graphite (P-EG Q m = 0.770 mg/g; G-EG Q m = 0.507 mg/g). The physicochemical properties of EG and G-P-EG were characterized by N 2 adsorption/desorption, Boehm's titration and X-ray photoelectron spectroscopy (XPS). EG exhibited higher values of BET surface area (11.357 m 2 /g) and total pore volume (0.0303 cm 3 /g) than that of G-P-EG (4.808 m 3 /g and 0.0109 cm 3 /g). However, the results of Bohm's titration and XPS showed that G-P-EG contained more surface oxygen-containing functional groups. The Ni(II) adsorption equilibrium data agreed well with the Langmuir model. And the experimental data of EG and G-P-EG fitted better by pseudo-second order model. Based on the results of batch adsorption experiments and XPS analysis, there were several possible mechanisms for Ni(II) adsorption on the G-P-EG, including chemical adsorption, cation exchange, electrostatic attraction and surface complication.

  1. Color stable manganese-doped phosphors

    Science.gov (United States)

    Lyons, Robert Joseph [Burnt Hills, NY; Setlur, Anant Achyut [Niskayuna, NY; Deshpande, Anirudha Rajendra [Twinsburg, OH; Grigorov, Ljudmil Slavchev [Sofia, BG

    2012-08-28

    A process for preparing color stable Mn.sup.+4 doped phosphors includes providing a phosphor of formula I; A.sub.x[MF.sub.y]:Mn.sup.+4 I and contacting the phosphor in particulate form with a saturated solution of a composition of formula II in aqueous hydrofluoric acid; A.sub.x[MF.sub.y]; II wherein A is Li, Na, K, Rb, Cs, NR.sub.4 or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; R is H, lower alkyl, or a combination thereof; x is the absolute value of the charge of the [MF.sub.y] ion; and y is 5, 6 or 7. In particular embodiments, M is Si, Ge, Sn, Ti, Zr, or a combination thereof. A lighting apparatus capable of emitting white light includes a semiconductor light source; and a phosphor composition radiationally coupled to the light source, and which includes a color stable Mn.sup.+4 doped phosphor.

  2. Luminescent phosphor materials

    International Nuclear Information System (INIS)

    Jamieson, P.B.

    1980-01-01

    The invention relates to luminescent phosphors and in particular those phosphors which emit ultra-violet radiation when struck by X-rays. The formula of the phosphor is Lasub(1-x-y-z-a)Gdsub(x)Cesub(y)Tbsub(z)Thsub(a)XO 4 in which X represents phosphorus atoms, arsenic atoms or a mixture of phosphorus and arsenic atoms, x is 0.01 to 0.50 and preferably 0.05 to 0.30, y is 0 or up to 0.50, z is 0 or up to 0.10 and preferably 0 or up to 0.02, a is 0 or up to 0.02, and when X represents phosphor atoms alone y + z + a is at least 0.01. The phosphors emit strong ultra-violet radiation when irradiated by X-rays and so can be used in intensifying screens particularly where the photographic material is UV radiation sensitive. In this case the overall emission should be in the 250-400 nm wavelength range. Another use is in the emission coating of cathode ray tubes. Details of the characteristics of various compositions are given with examples of preparation and emission spectra. (UK)

  3. Contribution to the study of the physico-chemical mechanisms of metallic cation extraction by alkylphosphoric acids. Extraction of zirconium (IV) by di-2-ethylhexyl phosphoric acid (DEHPA)

    International Nuclear Information System (INIS)

    Carbonnier, J.-L.

    1979-02-01

    Extraction of zirconium, especially at high concentration (0.1M), by dodecane diluted DEHPA (HA) from hydrochloric or nitric aqueous phases of 0.1 to 10 M acidity was studied. The composition, structure and polymerisation of the complexes extracted were determined by chemical analysis, viscosimetry, infrared spectrometry and light scattering. A Zr(OH) 2 A 2 .2HNO 3 , type structure is proposed for these complexes instead of the generally accepted form: Zr(OH) 2 (NO 3 ) 2 .2HA. Similarly in hydrochloric solution: Zr(OH) 2 A 2 .2HCl. Polymerisation in the organic phase results from the juxtaposition of two factors; firstly zirconium saturation (formation of bridges by DEHPA between zirconium atoms) and secondly the nature the equeous phase. In slightly acid hydrochloric solution (pH = 1.3) the aqueous plymers of zirconium are extracted in the organic phase as polynuclear complexes; in nitric solution no polynuclear complexes are observed but the nitric acid molecules extracted set up hydrogen bonds which explain the increased viscosity and gelification of the organic phases [fr

  4. Development of an overall technology for phosphoric acid fuel cells. ; Research and development of a fuel cell power generation system for business use. Rinsangata nenryo denchi no sogoteki gijutsu kaihatsu. ; Gyomuyo nenryo denchi hatsuden system no kenkyu kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    1994-02-01

    This paper reports the research and development work on a fuel cell power generation system using phosphoric acid fuel cells for business use. The system researches have included pre-investigation on loads, and discussions on methods to recover heat generated from fuel cells, a performance test, an actual load test, and a trap test in the operational tests. High-temperature thermal output from the fuel cells will be used in a double-effect absorption water freezing/heating machine as a load for air conditioning of guest rooms in a hotel. Low-temperature thermal output will be connected to a part of the hot-water supply systems in a kitchen and guest rooms. The elementary researches have been performed for studies on fuel cell technologies and improvement of fuel cell characteristics. High-performance cooling technologies, reforming technologies, and inverter technologies have been studied, and the system for 100-kW class plant machines has been reviewed. The elementary researches have been used to execute a basic design for a 200-kW fuel cell power plant for business use. A high-performance turbine and a compressor have been developed. Developments have been made on tertiary system catalysts, and capacity increase in phosphoric acid storage system using separators with composite ribs as technologies for improving the fuel cell characteristics. 30 figs., 7 tabs.

  5. Phosphorus, phosphorous, and phosphate.

    Science.gov (United States)

    Iheagwara, O Susan; Ing, Todd S; Kjellstrand, Carl M; Lew, Susie Q

    2013-10-01

    This article distinguishes the terms "phosphorus, phosphorous, and phosphate" which are frequently used interchangeably. We point out the difference between phosphorus and phosphate, with an emphasis on the unit of measure. Expressing a value without the proper name or unit of measure may lead to misunderstanding and erroneous conclusions. We indicate why phosphate must be expressed as milligrams per deciliter or millimoles per liter and not as milliequivalents per liter. Therefore, we elucidate the distinction among the terms "phosphorus, phosphorous, and phosphate" and the importance of saying precisely what one really means. © 2012 The Authors. Hemodialysis International © 2012 International Society for Hemodialysis.

  6. Evaluation of phosphorous biofertilizer and chemical phosphorous influence on fodder quality of corn (Zea mays L. and grass pea (Lathyrus sativa L. intercropping

    Directory of Open Access Journals (Sweden)

    M. Naghizadeh

    2016-05-01

    Full Text Available Intercropping is considered as a method for increasing yield per unit and stability. In order to evaluate the effects of phosphorous biofertilizer and chemical phosphorous on fodder quality of corn (Zea mays L. and grass pea (Lathyrus sativa L. intercropping, two field experiments were conducted as factorial based on randomized complete block design with four replications at two places simultaneously in Kerman and Bardsir during growing season of 2009-2010. The investigated factors included four levels of phosphorous fertilizer (100 g.ha-1 of phosphorous biofertilizer, 150 kg.ha-1 of chemical fertilizer, %50 phosphorous biofertilizer+%50 chemical phosphorous and control and five replacement intercropping patterns consist of sole crop of corn and grass pea, various proportions of corn and grass pea (75:25, 50:50 and 25:75. The result showed that the location effect on dry matter digestibility, crude protein, ash percentage, neutral detergent fiber and acid detergent fiber was significant but location effect on water soluble carbohydrate was not significant. Moreover, dry matter digestibility, crude protein, ash percentage, neutral detergent fiber, acid detergent fiber and water soluble carbohydrate influenced by various proportions of intercropping, extremely. Also, phosphorous applying on all of mentioned traits was significant, unless ash percentage. Dry matter digestibility, water soluble carbohydrate and crude protein of fodder influenced by various proportions of intercropping×phosphorous fertilizer interaction. Various proportions of corn and grass pea intercropping had higher fodder quality than sole cop of them; because, they had higher values of dry Matter digestibility, crude protein, water soluble carbohydrate and ash Percentage and lower values of neutral detergent fiber and acid detergent fiber. Dabble application of phosphorous biofertilizer and chemical phosphorous promote fodder quality due to increase solubility of insoluble

  7. Threshold changes in rat brain docosahexaenoic acid incorporation and concentration following graded reductions in dietary alpha-linolenic acid

    Science.gov (United States)

    Taha, Ameer Y.; Chang, Lisa; Chen, Mei

    2016-01-01

    Background This study tested the dietary level of alpha-linolenic acid (α-LNA, 18:3n-3) sufficient to maintain brain 14C-Docosahexaenoic acid (DHA, 22:6n-3) metabolism and concentration following graded α-LNA reduction. Methods 18–21 day male Fischer-344 (CDF) rats were randomized to the AIN-93G diet containing as a % of total fatty acids, 4.6% (“n-3 adequate”), 3.6%, 2.7%, 0.9% or 0.2% (“n-3 deficient”) α-LNA for 15 weeks. Rats were intravenously infused with 14C-DHA to steady state for 5 minutes, serial blood samples collected to obtain plasma and brains excised following microwave fixation. Labeled and unlabeled DHA concentrations were measured in plasma and brain to calculate the incorporation coefficient, k*, and incorporation rate, Jin. Results Compared to 4.6% α-LNA controls, k* was significantly increased in ethanolamine glycerophospholipids in the 0.2% α-LNA group. Circulating unesterified DHA and brain incorporation rates (Jin) were significantly reduced at 0.2% α-LNA. Brain total lipid and phospholipid DHA concentrations were reduced at or below 0.9% α-LNA. Conclusion Threshold changes for brain DHA metabolism and concentration were maintained at or below 0.9% dietary α-LNA, suggesting the presence of homeostatic mechanisms to maintain brain DHA metabolism when dietary α-LNA intake is low. PMID:26869088

  8. Teor de fósforo e pH no bulbo molhado, com diferentes freqüências de fertirrigação, utilizando ácido fosfórico Phosphorous content and pH in the wet bulb, with diferent frequencies of fertigation using phosphoric acid

    Directory of Open Access Journals (Sweden)

    Leticia C. Foratto

    2007-08-01

    Full Text Available A aplicação de fertilizantes fosfatados, tais como superfosfofato simples, superfosfofato triplo e monofosfato de amônio, via gotejamento, pode apresentar incrustações nas canalizações e obstruções de emissores. No presente trabalho, realizado na UNESP/Jaboticabal - SP, estudaram-se a distribuição do fósforo e a sua influência sobre o pH e a umidade em Latossolo Vermelho, fertirrigado durante um mês, com cinco aplicações semanais de ácido fosfórico. Utilizaram-se quatro repetições e oito tratamentos, constituídos da combinação de doses de P2O5 (0 e 50 kg ha-1 e freqüências de aplicação de 1; 3; 5 e 7 dias. Pelos resultados obtidos, observou-se que a freqüência de irrigação ou de fertirrigação não influenciou na distribuição final da umidade no bulbo molhado; aplicando-se o ácido fosfórico, o pH do solo até 30 cm do gotejador e até 40 cm em profundidade foi reduzido, atingindo valor de 3,6, e o teor de fósforo foi maior nessa mesma porção do bulbo, ultrapassando 1.500 mg dm-3. Isso permite indicar que o ácido fosfórico pode ser utilizado em irrigação localizada, com controle do pH do solo, pois sua redução influencia no desenvolvimento das culturas e, conseqüentemente, na produtividade.Phosphated fertilizers, such as superphosphate, triple superphosphate and monoamonium phosphate, applied throught drip irrigation can present pipe incrustations and emitters obstructions. In this research, carried out in the UNESP - São Paulo State University, Jaboticabal - Brazil, it was studied the phosphorous distribution, the influence on pH and the moisture in one Oxisoil, fertigated during one month, with five applications of phosphoric acid. Four replications and eight treatments were applied, and the treatments combined two rates of P2O5 (0 and 50 kg ha-1 and four frequencies of applications (1; 3; 5 and 7 days. The irrigation or fertigation frequency did not influence the distribution of the moisture in

  9. Encapsulation of strontium aluminate phosphors to enhance water resistance and luminescence

    International Nuclear Information System (INIS)

    Zhu Yong; Zeng Jianghua; Li Wenyu; Xu Li; Guan Qiu; Liu Yingliang

    2009-01-01

    Strontium aluminate SrAl 2 O 4 :Eu 2+ ,Dy 3+ phosphors are chemically unstable against water or even moisture. To enhance the water resistance of the phosphors, an encapsulation was performed by direct surface reactions with phosphoric acid (H 3 PO 4 ). The morphology, surface structure, surface element composition, water resistance, luminescence, and photoacoustic spectrum of the phosphors before and after encapsulation were discussed. Experimental results showed that phosphors were perfectly encapsulated by amorphous layers in nanoscale and crystalline layers in microscale under different conditions. The water resistance of phosphors was greatly enhanced by the two types of layer. More importantly, the amorphous layers enhanced the luminescence of phosphors markedly. The possible mechanism for the enhancements was also proposed.

  10. Photoelectron Pumped Phosphors,

    Science.gov (United States)

    1989-07-01

    recombination of particles which were separated in the process of excitation. RL of semiconductors is the result of recombination of electrons and holes...relatively new phosphors, SnO 2 :Eu presents a certain interest not only because of its luminescence parameters, but also because of its secondary electron...the effective radiative recombination centers in some semiconductor compounas if their ion radius and electro-negativity differ substan- tially from

  11. Preparation and characterization of a composite based on Zr(IV) and phosphoric acid; Preparacao e caracterizacao de um composito a base de Zr(IV) e acido fosforico

    Energy Technology Data Exchange (ETDEWEB)

    Silveira, T.F.S. da; Carmo, D.R. do, E-mail: taylafserantoni@gmail.com [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Ilha Solteira, SP (Brazil). Faculdade de Engenharia. Departamento de Fisica e Quimica

    2014-07-01

    The present work describes the preparation and characterization of a composite formed from zirconium (IV) isopropoxide and phosphoric acid (ZrP). This composite (ZrP) was characterized by techniques such as infrared spectroscopy (FTIR), {sup 13}C and {sup 31}P nuclear magnetic resonance (NMR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and thermogravimetric analysis (TG). Vibrational spectrum for ZrP showed a band at ∼ 1010 cm{sup -1} assigned to the stretching P=O(νP=O). The results obtained by EDS confirmed the presence of elements Zr, P and O in the formed composite, and any C has been detected in concordance of NMR of {sup 13}C. The {sup 31}P NMR spectrum of ZrP showed two pronounced peaks characteristic of zirconium phosphate. In the TG curve three steps of weight loss were observed for ZrP. (author)

  12. Current status and emerging role of glutathione in food grade lactic acid bacteria

    Directory of Open Access Journals (Sweden)

    Pophaly Sarang

    2012-08-01

    Full Text Available Abstract Lactic acid bacteria (LAB have taken centre stage in perspectives of modern fermented food industry and probiotic based therapeutics. These bacteria encounter various stress conditions during industrial processing or in the gastrointestinal environment. Such conditions are overcome by complex molecular assemblies capable of synthesizing and/or metabolizing molecules that play a specific role in stress adaptation. Thiols are important class of molecules which contribute towards stress management in cell. Glutathione, a low molecular weight thiol antioxidant distributed widely in eukaryotes and Gram negative organisms, is present sporadically in Gram positive bacteria. However, new insights on its occurrence and role in the latter group are coming to light. Some LAB and closely related Gram positive organisms are proposed to possess glutathione synthesis and/or utilization machinery. Also, supplementation of glutathione in food grade LAB is gaining attention for its role in stress protection and as a nutrient and sulfur source. Owing to the immense benefits of glutathione, its release by probiotic bacteria could also find important applications in health improvement. This review presents our current understanding about the status of glutathione and its role as an exogenously added molecule in food grade LAB and closely related organisms.

  13. Effects of Peracetic Acid on the Corrosion Resistance of Commercially Pure Titanium (grade 4).

    Science.gov (United States)

    Raimundo, Lariça B; Orsi, Iara A; Kuri, Sebastião E; Rovere, Carlos Alberto D; Busquim, Thaís P; Borie, Eduardo

    2015-01-01

    The aim of this study was to evaluate the corrosion resistance of pure titanium grade 4 (cp-Ti-4), subjected to disinfection with 0.2% and 2% peracetic acid during different immersion periods using anodic potentiodynamic polarization test in acid and neutral artificial saliva. Cylindrical samples of cp-Ti-4 (5 mm x 5 mm) were used to fabricate 24 working electrodes, which were mechanically polished and divided into eight groups (n=3) for disinfection in 2% and 0.2% peracetic acid for 30 and 120 min. After disinfection, anodic polarization was performed in artificial saliva with pH 4.8 and 6.8 to assess the electrochemical behavior of the electrodes. A conventional electrochemical cell, constituting a reference electrode, a platinum counter electrode, and the working electrode (cp-Ti specimens) were used with a scanning rate of 1 mV/s. Three curves were obtained for each working electrode, and corrosion was characterized by using scanning electron microscopy (SEM) and energy dispersive x-ray spectrometry (EDS). Data of corrosion potential (Ecorr) and passive current (Ipass) obtained by the polarization curves were analyzed statistically by Student's t-test (a=0.05). The statistical analysis showed no significant differences (p>0.05) between artificial saliva types at different concentrations and periods of disinfection, as well as between control and experimental groups. No surface changes were observed in all groups evaluated. In conclusion, disinfection with 0.2% and 2% peracetic acid concentrations did not cause corrosion in samples manufactured with cp-Ti-4.

  14. Taxa de emissão de CO2 de um latossolo fertirrigado com ácido fosfórico por gotejamento CO2 emission rate from a fertigated bare soil with phosphoric acid by dripping

    Directory of Open Access Journals (Sweden)

    José R. Zanini

    2005-04-01

    Full Text Available A aplicação de fertilizantes fosfatados por meio de fertirrigação com sistemas de irrigação localizada pode causar obstrução de emissores. Para evitar esse problema, pode ser utilizado o ácido fosfórico como fonte de fósforo às plantas. Porém, têm sido pouco investigados os efeitos da irrigação relacionados às perdas de CO2 do solo para a atmosfera, em conseqüência da decomposição do carbono orgânico e da infiltração de água no solo. Neste trabalho, investigou-se, no período de um mês, o efeito da fertirrigação com ácido fosfórico nas taxas de emissão de CO2 de um latossolo desprovido de vegetação, na Área Experimental de Irrigação da UNESP, Câmpus de Jaboticabal - SP. Utilizou-se de um sistema de irrigação por gotejamento, com delineamento experimental em blocos casualizados, constando de cinco repetições e cinco tratamentos (0; 30; 60; 90 e 120 kg ha-1de P2O5, aplicados via fertirrigação com ácido fosfórico. Verificou-se que as taxas de emissão de CO2 aumentaram significativamente após as fertirrigações, porém não houve efeito da dose do ácido fosfórico sobre as taxas. A umidade do solo mostrou-se um fator importante na relação entre as variações das taxas de emissão e a temperatura do solo ao longo do período estudado.The application of phosphoric fertilizers through fertigation, with localized irrigation systems, can cause emitters obstruction. In order to avoid this problem, the phosphoric acid can be used as phosphorus source to the plants. However, it has been little investigations on the effects of the irrigation practices, related to the CO2 transference to the atmosphere, due to organic matter decomposition in the soil and its water infiltration. At this work, the rates of emissions of CO2 from a bare soil without vegetation, and fertigated along one month were investigated. The experiment was conducted with randomized blocks design in São Paulo State University - UNESP

  15. Blue light emitting thiogallate phosphor

    Science.gov (United States)

    Dye, Robert C.; Smith, David C.; King, Christopher N.; Tuenge, Richard T.

    1998-01-01

    A crystalline blue emitting thiogallate phosphor of the formula RGa.sub.2 S.sub.4 :Ce.sub.x where R is selected from the group consisting of calcium, strontium, barium and zinc, and x is from about 1 to 10 atomic percent, the phosphor characterized as having a crystalline microstructure on the size order of from about 100 .ANG. to about 10,000 .ANG. is provided together with a process of preparing a crystalline blue emitting thiogallate phosphor by depositing on a substrate by CVD and resultant thin film electroluminescent devices including a layer of such deposited phosphor on an ordinary glass substrate.

  16. Triple-layered PLGA/nanoapatite/lauric acid graded composite membrane for periodontal guided bone regeneration.

    Science.gov (United States)

    Jamuna-Thevi, Kalitheertha; Saarani, Nur Najiha; Abdul Kadir, Mohamed Rafiq; Hermawan, Hendra

    2014-10-01

    This paper discusses the successful fabrication of a novel triple-layered poly(lactic-co-glycolic acid) (PLGA)-based composite membrane using only a single step that combines the techniques of solvent casting and thermally induced phase separation/solvent leaching. The resulting graded membrane consists of a small pore size layer-1 containing 10 wt% non-stoichiometric nanoapatite (NAp)+1-3 wt% lauric acid (LA) for fibroblastic cell and bacterial inhibition, an intermediate layer-2 with 20-50 wt% NAp+1 wt% LA, and a large pore size layer-3 containing 30-100 wt% NAp without LA to allow bone cell growth. The synergic effects of 10-30 wt% NAp and 1 wt% LA in the membrane demonstrated higher tensile strength (0.61 MPa) and a more elastic behavior (16.1% elongation at break) in 3 wt% LA added membrane compared with the pure PLGA (0.49 MPa, 9.1%). The addition of LA resulted in a remarkable plasticizing effect on PLGA at 3 wt% due to weak intermolecular interactions in PLGA. The pure and composite PLGA membranes had good cell viability toward human skin fibroblast, regardless of LA and NAp contents. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Temperature effects on the nitric acid oxidation of industrial grade multiwalled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Nadia F., E-mail: nadia@fisica.ufc.br [Universidade Federal do Ceara, Departamento de Fisica (Brazil); Martinez, Diego Stefani T., E-mail: diegostefani.br@gmail.com; Paula, Amauri J., E-mail: amaurijp@gmail.com [Universidade Estadual de Campinas (UNICAMP), Laboratorio de Quimica do Estado Solido (LQES), Instituto de Quimica (Brazil); Silveira, Jose V. [Universidade Federal do Ceara, Departamento de Fisica (Brazil); Alves, Oswaldo L., E-mail: oalves@iqm.unicamp.br [Universidade Estadual de Campinas (UNICAMP), Laboratorio de Quimica do Estado Solido (LQES), Instituto de Quimica (Brazil); Souza Filho, Antonio G., E-mail: agsf@fisica.ufc.br [Universidade Federal do Ceara, Departamento de Fisica (Brazil)

    2013-07-15

    In this study, we report an oxidative treatment of multiwalled carbon nanotubes (MWCNTs) by using nitric acid at different temperatures (25-175 Degree-Sign C). The analyzed materials have diameters varying from 10 to 40 nm and majority lengths between 3 and 6 {mu}m. The characterization results obtained by different techniques (e.g., field emission scanning electron microscopy, thermogravimetric analysis, energy-filtered transmission electron microscopy, Braunauer, Emmet and Teller method, {zeta}-potential and confocal Raman spectroscopy) allowed us to access the effects of temperature treatment on the relevant physico-chemical properties of the MWCNTs samples studied in view of an integrated perspective to use these samples in a bio-toxicological context. Analytical microbalance measurements were used to access the purity of samples (metallic residue) after thermogravimetric analysis. Confocal Raman spectroscopy measurements were used to evaluate the density of structural defects created on the surface of the tubes due to the oxidation process by using 2D Raman image. Finally, we have demonstrated that temperature is an important parameter in the generation of oxidation debris (a byproduct which has not been properly taken into account in the literature) in the industrial grade MWCNTs studied after nitric acid purification and functionalization.

  18. Polymorphism of phosphoric oxide

    Science.gov (United States)

    Hill, W.L.; Faust, G.T.; Hendricks, S.B.

    1943-01-01

    The melting points and monotropic relationship of three crystalline forms of phosphoric oxide were determined by the method of quenching. Previous vapor pressure data are discussed and interpreted to establish a pressure-temperature diagram (70 to 600??) for the one-component system. The system involves three triple points, at which solid, liquid and vapor (P4O10) coexist in equilibrium, namely: 420?? and 360 cm., 562?? and 43.7 cm. and 580?? and 55.5 cm., corresponding to the hexagonal, orthorhombic and stable polymorphs, respectively, and at least two distinct liquids, one a stable polymer of the other, which are identified with the melting of the stable form and the hexagonal modification, respectively. Indices of refraction of the polymorphs and glasses were determined. The density and the thermal, hygroscopic and structural properties of the several phases are discussed.

  19. Adsorption of Free Fatty Acid (FFA) in Low-Grade Cooking Oil Used Activated Natural Zeolite as Adsorbent

    Science.gov (United States)

    Larasati Tres Ayu Putranti, Monika; Kompiang Wirawan, Sang; Made Bendiyasa, I.

    2018-01-01

    Adsorption of free fatty acid (FFA) in low-grade cooking oil using active natural zeolite adsorbent was done as an effort to improve the quality of low-grade cooking oil so that it can fulfill the standard of fried oil which has been set on SNI 01-3741-2013. Adsorption was carried out with natural zeolite which activated with HCl and NaOH solution followed by the calcination process. The results showed that the NaOH activated zeolite decreased FFA content in low-grade cooking oil more than the HCl activated natural zeolite, with optimum NaOH concentration was 0.75 M. In the adsorption equilibrium analysis with temperature variation (25 °C, 40 °C, 80 °C ), obtained that adsorption of FFA with NaOH activated natural zeolite follows Adsorption Isotherm Freundlich Model with equilibrium constant value was 20,5873; 0,9629 dan 0,8053.

  20. Effect of Mg2+, Al3+, and Fe3+ ions on crystallization of type α hemi-hydrated calcium sulfate under simulated conditions of hemi-hydrate process of phosphoric acid

    Science.gov (United States)

    Yang, Lin; Cao, Jianxin; Luo, Tong

    2018-03-01

    The present study investigated the effects of Mg2+, Al3+, and Fe3+ ions, as additives, on crystallization of type α hemi-hydrated calcium sulfate (α-HH) under simulated conditions of hemi-hydrate wet-process phosphoric acid production. Results showed that induction time of α-HH without additives reduces with increasing supersaturated ratios, but increases in the presence of Mg2+, Al3+, and Fe3+ ions. Under the same concentration of impurity ions, the order of extending induction time of α-HH is as follows: Fe3+>Mg2+>Al3+, and surface energy and critical nucleus radius of α-HH increase in the presence of Mg2+, Al3+, and Fe3+ ions. Accordingly, nucleation rate and growth efficiency of α-HH crystals reduce. Length of α-HH crystals decreases and its diameter thicken in the presence of Mg2+, Al3+, and Fe3+ ions. The crystals of α-HH easily grow in the direction of [0 1 0], and feature long-needles. On the other hand, Mg2+, Al3+, and Fe3+ ions are mainly adsorbed on the exposed surface {1 -1 0} of α-HH crystals. Thus, crystal shapes of α-HH eventually show wedge or short columns.

  1. Decoupling of dynamic processes in surfactant-based liquid mixtures: the case of lithium-containing bis(2-ethylhexyl)phosphoric acid/bis(2-ethylhexyl)amine systems.

    Science.gov (United States)

    Nicotera, Isabella; Oliviero Rossi, Cesare; Turco Liveri, Vincenzo; Calandra, Pietro

    2014-07-22

    Pure surfactant liquids and their binary mixtures, because of the amphiphilic nature of the molecules involved, can exhibit nanosegregation and peculiar transport properties. The idea that inspired this work is that the possibility of including in such media salts currently used for technological applications should lead to a synergy between the properties of the salt and those of the medium. Therefore, the dynamic features of bis(2-ethylhexyl)amine (BEEA) and bis(2-ethylhexyl)phosphoric acid (HDEHP) liquid mixtures were investigated as a function of composition and temperature by (1)H nuclear magnetic resonance (NMR) spectroscopy and rheometry. Inclusion of litium trifluoromethanesulfonate (LiT) has been investigated by infrared spectroscopy, pulsed field gradient NMR, and conductimetry methods to highlight the solubilizing and confining properties of these mixtures as well as the lithium conductivity. It was found that BEEA/HDEHP binary liquid mixtures show zero-threshold percolating self-assembly with a maximum in viscosity and a minimum in molecular diffusion at a 1:1 composition. Dissolution of LiT in such system can occur via confinement in the locally self-assembled polar domains. Despite this confinement, Li(+) conduction is scarcely dependent on the medium composition because of the possibility of a field-induced hopping decoupled by the structural and dynamical features of the medium.

  2. Study of phosphorous based resins for the uptake of plutonium from H2SO4 based analytical waste

    International Nuclear Information System (INIS)

    Seshadri, H.; Mohandas, Jaya; Srinivasan, S.; Kumar, T.; Rajan, S.K.

    2006-01-01

    This study indicates that phosphorous based resins can be conveniently employed for the uptake of plutonium from analytical wastes even in strong acid media and also in the presence of diverse ions like silver and chromium. It is also evident that phosphorous based resins have proved to be efficient even in sulphuric acid medium

  3. Fiscal 1997 report on the results of the international standardization R and D. R and D of the standardization of a method to test acceleration life of phosphorous acid fuel cells; 1997 nendo seika hokokusho kokusai hyojun soseigata kenkyu kaihatsu. Rinsangata nenryo denchi no kasoku jumyo shiken hoho no hyojunka ni kansuru kenkyu kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    As for fuel cells, which are expected as a new clean energy, the R and D are being proceeded with in various fields of the world, but the standardization has not been made both in Japan and abroad. In Japan, the situation is that the information on technical terms, indication method, performance test method, and environment/safety test methods of the phosphorous acid fuel cell power generation is publicly spread. In relation to the international promotion of fuel cells to be predicted, it is necessary to internationally standardize cells themselves which are a key component of fuel cell power generation facilities. Phosphorous acid fuel cells are expected of the earliest commercialization of all, but the common test method to evaluate life characteristics of the cell stack has not been established yet. In the R and D, for the purpose of internationally standardizing test methods to evaluate life characteristics of the cell stack, a study on the acceleration life test method of phosphoric acid fuel cells was conducted in terms of the technical trend, data, standard, etc. A plan was prepared on general rules of the method to test acceleration life at the cell reaction part of the small cell, and activities also were started for setting up a technical committee for the fuel cell power system in President`s Advisory Committee on Future Technology. 29 figs., 20 tabs.

  4. Acid Rain: A Teacher's Guide. Activities for Grades 4 to 12.

    Science.gov (United States)

    National Wildlife Federation, Washington, DC.

    This guide on acid rain for elementary and secondary students is divided into three study areas: (1) What Causes Acid Rain; (2) What Problems Acid Rain Has Created; (3) How You and Your Students Can Help Combat Acid Rain. Each section presents background information and a series of lessons pertaining to the section topic. Activities include…

  5. The association between low-grade inflammation, iron status and nucleic acid oxidation in the elderly

    DEFF Research Database (Denmark)

    Broedbaek, Kasper; Siersma, Volkert Dirk; Andersen, Jon T

    2011-01-01

    markers of nucleic acid oxidation between cases and controls were found and multivariable linear regression analysis showed no association between urinary markers of nucleic acid oxidation and inflammatory markers. Post-hoc multivariable linear regression analysis showed significant associations between...

  6. Inorganic Phosphor Materials for Lighting.

    Science.gov (United States)

    Lin, Yuan-Chih; Karlsson, Maths; Bettinelli, Marco

    2016-04-01

    This chapter addresses the development of inorganic phosphor materials capable of converting the near UV or blue radiation emitted by a light emitting diode to visible radiation that can be suitably combined to yield white light. These materials are at the core of the new generation of solid-state lighting devices that are emerging as a crucial clean and energy saving technology. The chapter introduces the problem of white light generation using inorganic phosphors and the structure-property relationships in the broad class of phosphor materials, normally containing lanthanide or transition metal ions as dopants. Radiative and non-radiative relaxation mechanisms are briefly described. Phosphors emitting light of different colors (yellow, blue, green, and red) are described and reviewed, classifying them in different chemical families of the host (silicates, phosphates, aluminates, borates, and non-oxide hosts). This research field has grown rapidly and is still growing, but the discovery of new phosphor materials with optimized properties (in terms of emission efficiency, chemical and thermal stability, color, purity, and cost of fabrication) would still be of the utmost importance.

  7. [The Correlation between Blood Uric Acid and Goldstein Grading in Hepatolenticular Degeneration Patients with Different Chinese Medical Syndrome Types].

    Science.gov (United States)

    Hu, Ji-yuan; Han, Yong-zhu; Ye, Qun-rong; Hong, Ming-fan; Cai, Yong-liang; Ren, Ming-shan; Pan, Fa-ming; Wang, Xun; Yang, Ren-ming

    2015-11-01

    To observe blood uric acid levels and Goldstein grading, as well as their correlation in Wilson's disease (WD) patients with different Chinese medical syndrome types. Totally 906 WD patients in line with inclusive criteria were assigned to 6 groups, i.e., the heart spirit confused by phlegm group (HSCP, 26 cases), the phlegm-fire disturbing heart group (PFDH, 90 cases), the retention of damp-heat group (RDH, 113 cases), deficiency of qi and blood group (DQB, 168 cases), the deficiency of Gan-yin and Shen-yin group (DGYSY, 327 cases), the deficiency of Gan and Shen group (DGS, 182 cases) due to different Chinese medical syndrome types. Recruited were another 160 healthy subjects having similar ages and diet structures, who came for medical examinations, as the healthy control group. Venous blood was collected from the medial cubital vein of each-patient on an empty stomach in early mornings to detect blood uric acid levels. Results Blood uric acid levels were lower in each syndrome type group than in the healthy control group (146.08 +/- 67.24 micromol/L in the HSCP group; 157.08 +/- 69.77 micromol/L in the PFDH group; 162.58 +/- 97.72 micromol/L in the RDH group; 156.20 +/- 62.63 micromol/L in the DQB group; 161.83 +/- 111.23 micromol/L in the DGYSY group; 194.41 +/- 90.01 micromol/L in the DGS group; 242.39 +/- 87.55 micromol/L in the healthy control group, P levels were higher in the DGYSY group than in the other 5 syndrome groups (P levels decreased (P levels decreased more. Blood uric acid levels and Goldstein grading were different in various Chinese medical syndrome types. Blood uric acid levels had certain value in assessing the severity of WD.

  8. Excess ω-6 fatty acids influx in aging drives metabolic dysregulation, electrocardiographic alterations, and low-grade chronic inflammation.

    Science.gov (United States)

    Kain, Vasundhara; Ingle, Kevin A; Kachman, Maureen; Baum, Heidi; Shanmugam, Gobinath; Rajasekaran, Namakkal S; Young, Martin E; Halade, Ganesh V

    2018-02-01

    Maintaining a balance of ω-6 and ω-3 fatty acids is essential for cardiac health. Current ω-6 and ω-3 fatty acids in the American diet have shifted from the ideal ratio of 2:1 to almost 20:1; while there is a body of evidence that suggests the negative impact of such a shift in younger organisms, the underlying age-related metabolic signaling in response to the excess influx of ω-6 fatty acids is incompletely understood. In the present study, young (6 mo old) and aging (≥18 mo old) mice were fed for 2 mo with a ω-6-enriched diet. Excess intake of ω-6 enrichment decreased the total lean mass and increased nighttime carbohydrate utilization, with higher levels of cardiac cytokines indicating low-grade chronic inflammation. Dobutamine-induced stress tests displayed an increase in PR interval, a sign of an atrioventricular defect in ω-6-fed aging mice. Excess ω-6 fatty acid intake in aging mice showed decreased 12-lipoxygenase with a concomitant increase in 15-lipoxygenase levels, resulting in the generation of 15( S)-hydroxyeicosatetraenoic acid, whereas cyclooxygenase-1 and -2 generated prostaglandin E 2 , leukotriene B 4, and thromboxane B 2 . Furthermore, excessive ω-6 fatty acids led to dysregulated nuclear erythroid 2-related factor 2/antioxidant-responsive element in aging mice. Moreover, ω-6 fatty acid-mediated changes were profound in aging mice with respect to the eicosanoid profile while minimal changes were observed in the size and shape of cardiomyocytes. These findings provide compelling evidence that surplus consumption of ω-6 fatty acids, coupled with insufficient intake of ω-3 fatty acids, is linked to abnormal changes in ECG. These manifestations contribute to functional deficiencies and expansion of the inflammatory mediator milieu during later stages of aging. NEW & NOTEWORTHY Aging has a profound impact on the metabolism of fatty acids to maintain heart function. The excess influx of ω-6 fatty acids in aging perturbed

  9. A review of food-grade vectors in lactic acid bacteria: from the laboratory to their application.

    Science.gov (United States)

    Landete, José Maria

    2017-05-01

    Lactic acid bacteria (LAB) have a long history of use in fermented foods and as probiotics. Genetic manipulation of these microorganisms has great potential for new applications in food safety, as well as in the development of improved food products and in health. While genetic engineering of LAB could have a major positive impact on the food and pharmaceutical industries, progress could be prevented by legal issues related to the controversy surrounding this technology. The safe use of genetically modified LAB requires the development of food-grade cloning systems containing only the DNA from homologous hosts or generally considered as safe organisms, and not dependent antibiotic markers. The rationale for the development of cloning vectors derived from cryptic LAB plasmids is the need for new genetic engineering tools, therefore a vision from cryptic plasmids to applications in food-grade vectors for LAB plasmids is shown in this review. Replicative and integrative vectors for the construction of food-grade vectors, and the relationship between resistance mechanism and expression systems, will be treated in depth in this paper. Finally, we will discuss the limited use of these vectors, and the problems arising from their use.

  10. Response of Groundnut (�JL-24� Cultivar to Mycorrhiza Inoculation and Phosphorous Application

    Directory of Open Access Journals (Sweden)

    Khirood DOLEY

    2012-08-01

    Full Text Available A pot experiment was conducted on peanut Arachis hypogaea L. during 2007 growing season to determine their growth characteristics due to mycorrhizal inoculation and two different levels of soluble phosphorous application. Due to inoculation by AM fungi the growth parameters such as leaf number, shoot length, root length, fresh weight, dry weight, pod number and nodule number were significantly increased but two different level of phosphate also showed growth. However, growth parameters showed variable results when two different level of phosphate was applied along with AM fungi. Without phosphorous the mycorrhizal groundnut showed significant growth but when first low level of phosphorous was applied it showed more significant growth, however most significant result was observed with second high level of phosphorous application to the groundnut plant. Total chlorophyll content and acid and alkaline phosphatase activity was also significantly higher but most significant were observed when first level of phosphorous was applied followed by second level of phosphorous. The percent root colonization by mycorrhizal fungus Glomus fasciculatum was higher due to application of phosphorous but mycorrhizal dependency went on decreasing due to increase in the level of phosphorous. The different level of phosphorous had significant effect on growth and physiological parameters of mycorrhizal and non-mycorrhizal Arachis plants after 30, 60 and 90 days of growth period. However, the obtained results proved the improvement in plant growth with application of phosphorous. Thus, for increase in production of groundnut in the state of Maharashtra seems to be feasible option for increasing the overall production and yield.

  11. Phosphorous pentoxide mediated synthesis of 5-HMF in ionic liquid at low temperature.

    Science.gov (United States)

    Ray, Devalina; Mittal, Neha; Chung, Wook-Jin

    2011-10-18

    A convenient, mild and environment-friendly dehydration reaction of fructose in ionic liquid using phosphorous pentoxide (P(2)O(5)) has been investigated. The acidic nature of P(2)O(5) along with its hygroscopic properties has been successfully utilized to afford 81.2% yield of 5-hydroxymethylfurfural (5-HMF) at 50°C in 60 mins. Phosphoric acid yielded remarkably less 5-HMF even at higher temperature and longer reaction times. The reaction was optimized by varying different parameters and the results indicated that no rehydration products, such as levulinic acid or formic acid, were formed. Copyright © 2011 Elsevier Ltd. All rights reserved.

  12. Effects of dietary lead exposure and graded levels of ascorbic acid ...

    African Journals Online (AJOL)

    The effects of dietary lead acetate (LA) exposure on growth performance and haematological characteristics of broiler chickens and possible ameliorative effect of ascorb ic acid (AA) were investigated. One hundred and twenty day-old broiler chicks were randomly divided into six treatment groups of 20 birds with two ...

  13. The relation of saturated fatty acids with low-grade inflammation and cardiovascular disease

    NARCIS (Netherlands)

    Ruiz-Nunez, Begona; Dijck-Brouwer, D. A. Janneke; Muskiet, Frits A. J.

    2016-01-01

    The mantra that dietary (saturated) fat must be minimized to reduce cardiovascular disease (CVD) risk has dominated nutritional guidelines for decades. Parallel to decreasing intakes of fat and saturated fatty acids (SFA), there have been increases in carbohydrate and sugar intakes, overweight,

  14. Phosphoric Acid Fuel Cells Test and Evaluation

    Science.gov (United States)

    2004-10-01

    system configurations and components to achieve lower life cycle cost either through reduced capital cost, reduced operation and maintenance (O&M... capital cost, reduced operation and maintenance (O&M) costs, or increased performance and reliability. Objective The objective of this work was to...samples of natural gas and proc- essed gases at access ports AP001, reformer inlet and AP003, reformer outlet in a batch method, using Suma canisters

  15. Why Not Replace pH and pOH by Just One Real Acidity Grade, AG?

    Science.gov (United States)

    van Lubeck, Henk

    1999-07-01

    The definition of pH according to Sörensen (1909) as pH = -log [H+] offers some striking disadvantages to beginning students in a chemistry course, especially those with no knowledge of logarithms. They will face some puzzling consequences of this definition such as (i) pH of a neutral solution equals 7.0, a value which changes with temperature, and (ii) pH of an acidic solution will rise after dilution. The corresponding disadvantages hold good for pOH in alkaline solutions. These disadvantages disappear after replacing pH and pOH by AG, the acidity grade: AG = log [H+]/[OH-]. AG of neutral solutions equals 0 at all temperatures, whereas AG of acidic solutions is positive and of alkaline solutions, negative. AG offers some other minor advantages as well. Anybody using AG in calculations needs some knowledge of chemical equilibrium, in particular the reversible heterolytic dissociation of water. However, breaking with a long tradition appears to be the major obstacle to an introduction of AG.

  16. Phosphorous loads evaluation from soil

    International Nuclear Information System (INIS)

    Mezzanotte, V.

    1996-01-01

    With reference to the well known difficulty of quantifying non point phosphorous loads, as well as to their growing relative importance where point source leads decrease, a literature review has been carried out concerning soil export coefficients. On such basis, the values which seem to be the most appropriate for Italy have been estimated for different land use categories. The main mechanisms determining non point phosphorous load generation and the factors affecting their importance are also described. In the end, criteria for estimating the importance of non point sources in a basin are suggested to be used for deciding whether a traditional, parametric assessment (inevitably involving a certain error) can be acceptable or experimental measures are needed

  17. Endoscopic Injection of Dextranomer/Hyaluronic Acid as First-Line Treatment in 851 Consecutive Children with High-Grade Vesicoureteral Reflux: Efficacy and Long-Term Results.

    Science.gov (United States)

    Friedmacher, Florian; Colhoun, Eric; Puri, Prem

    2018-03-15

    Endoscopic injection of dextranomer/hyaluronic is widely acknowledged as first-line treatment of lower grade vesicoureteral reflux. Our objective was to demonstrate its long-term efficacy and safety in eradicating high-grade reflux. Eight-hundred-fifty-one children (518 girls, 333 boys), median age 2.3 years (2 months-13.7 years), underwent endoscopic correction of high-grade vesicoureteral reflux using dextranomer/hyaluronic acid. Reflux was unilateral in 415 cases and bilateral in 436, comprising 1,287 refluxing units: grade IV in 1,153 (89.6%) and grade V in 134 (10.4%). 99m technetium-dimercaptosuccinic acid imaging identified renal scarring in 317 (37.3%) patients. Follow-up ultrasound and voiding cystourethrogram were performed 3 months post intervention and renal ultrasound annually thereafter. Median follow-up was 8.5 years (6 months-16 years). Overall resolution rate after the first endoscopic injection was 895/1,287 (69.5%): 70.4% in grade IV and 61.9% in grade V, respectively. Reflux resolved after a second injection in 259 (20.1%) and after a third in 133 (10.4%). Persistent reflux after initial treatment was significantly more common in infants injection of dextranomer/hyaluronic acid. Endoscopic injection of dextranomer/hyaluronic acid is an efficient and safe long-term treatment for grade IV and V vesicoureteral reflux, which can be easily repeated in cases of failure with a high subsequent resolution rate. Copyright © 2018 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  18. Radioluminescent nuclear batteries with different phosphor layers

    International Nuclear Information System (INIS)

    Hong, Liang; Tang, Xiao-Bin; Xu, Zhi-Heng; Liu, Yun-Peng; Chen, Da

    2014-01-01

    Highlights: • We present and test the electrical properties of the nuclear battery. • The best thickness range for ZnS:Cu phosphor layer is 12–14 mg cm −2 for 147 Pm radioisotope. • The best thickness range for Y 2 O 2 S:Eu phosphor layer is 17–21 mg cm −2147 Pm radioisotope. • The battery with ZnS:Cu phosphor layer can provide higher energy conversion efficiency. • The mechanism affecting the nuclear battery output performance is revealed. - Abstract: A radioluminescent nuclear battery based on the beta radioluminescence of phosphors is presented, and which consists of 147 Pm radioisotope, phosphor layers, and GaAs photovoltaic cell. ZnS:Cu and Y 2 O 2 S:Eu phosphor layers for various thickness were fabricated. To investigate the effect of phosphor layer parameters on the battery, the electrical properties were measured. Results indicate that the optimal thickness ranges for the ZnS:Cu and Y 2 O 2 S:Eu phosphor layers are 12 mg cm −2 to 14 mg cm −2 and 17 mg cm −2 to 21 mg cm −2 , respectively. ZnS:Cu phosphor layer exhibits higher fluorescence efficiency compared with the Y 2 O 2 S:Eu phosphor layer. Its spectrum properly matches the spectral response of GaAs photovoltaic cell. As a result, the battery with ZnS:Cu phosphor layer indicates higher energy conversion efficiency than that with Y 2 O 2 S:Eu phosphor layer. Additionally, the mechanism of the phosphor layer parameters that influence the output performance of the battery is discussed through the Monte Carlo method and transmissivity test

  19. Luminescence studies on phosphor screens

    International Nuclear Information System (INIS)

    Panayiotakis, G.; Nomikos, C.; Bakas, A.; Proimos, B.

    1994-01-01

    We report our results on x-ray phosphor screens prepared of some new materials focusing attention on their efficiency under fluoroscopy conditions, on optimization conditions and on comparisons among the various materials. All data are presented in absolute values. A theoretical model is presented, that takes into account the granular structure of the screens, permitting the explanation and prediction of the luminescence properties of the screens. (authors)

  20. Analysis of wide color gamut of green/red bilayered freestanding phosphor film-capped white LEDs for LCD backlight.

    Science.gov (United States)

    Oh, Ji Hye; Kang, Heejoon; Ko, Minji; Do, Young Rag

    2015-07-27

    In this study, we propose green/red bilayered freestanding phosphor film-capped white light-emitting diodes (W-LEDs) using InGaN blue LEDs and narrowband red and green phosphors to realize a wide color gamut in a liquid crystal display (LCD) backlight system. The narrowband K2SiF6:Mn4+ (KSF) red and SrGa2S4:Eu2+ (SGS) green phosphors are synthesized using a facile etching synthetic process and flux-aided solid state reaction under a H2S atmosphere, respectively, and the freestanding phosphor films are fabricated using a delamination method with water-soluble polymer, polystyrene sulfonic acid, PEDOT/PSS, and interlayered phosphor film. Various phosphor concentrations of green/red bilayered freestanding phosphor film-capped W-LEDs exhibit a correlated color temperature (CCT) and luminous efficacy range of 11,390 K ~6,540 K and 99 lm/W ~124 lm/W, respectively, with an applied current of 60 mA. The W-LED with green (12.5 wt%)/red (40 wt%) bilayered phosphor film, which exhibited luminous efficacy of 105 lm/W at the CCT of 8,330 K, is selected and the color gamut of the bare LED and phosphor RG and the filtered RGB triangle is calculated to be more than ~95% and ~86.4%, respectively, relative to the NTSC in the 1931 CIE color coordinates space.

  1. Quality parameters evaluation for the determination of available phosphorous in soils

    International Nuclear Information System (INIS)

    Garcia Galvis, John Brynner; Ballesteros, Maria Ines

    2006-01-01

    There are some colorimetric procedures for determining available phosphorous in soils, and phosphorous is evaluated by means of a blue complex (phosphomolybdic acid); in one of the methods, color appear when ascorbic acid is used as reductor agent, and in the other when stannous chloride is used. Both methods use the same extractive solution bray i i due to its good response for acid soil cultures, like most Colombian soils are. When the two methodologies were compared it was found that the most sensible method and with the best limit of detection and quantification was the one that uses ascorbic acid, antimonious and potassium tartrate. Its variation coefficients and standard deviation were lower, and for this reason it is considered as the most precise method for phosphorous determination

  2. Dextranomer/hyaluronic acid endoscopic injection is effective in the treatment of intermediate and high grade vesicoureteral reflux in patients with complete duplex systems.

    Science.gov (United States)

    Hunziker, Manuela; Mohanan, Nochiparambil; Puri, Prem

    2013-05-01

    Endoscopic subureteral injection of dextranomer/hyaluronic acid has become an established alternative to long-term antibiotic prophylaxis or surgical treatment for vesicoureteral reflux. We evaluated the effectiveness of endoscopic injection of dextranomer/hyaluronic acid in intermediate and high grade vesicoureteral reflux in patients with complete duplex collecting systems. A total of 123 children underwent endoscopic correction of intermediate or high grade vesicoureteral reflux using injection of dextranomer/hyaluronic acid into complete duplex systems between 2001 and 2010. Vesicoureteral reflux was diagnosed by voiding cystourethrogram, and dimercapto-succinic acid scan was performed to evaluate the presence of renal scarring. Followup ultrasound and voiding cystourethrogram were performed 3 months after the outpatient procedure and renal ultrasound thereafter every 2 years. Mean followup was 6.7 years. Complete duplex systems were unilateral in 110 patients and bilateral in 13. Reflux severity in the 136 refluxing units was grade II in 1 (0.7%), III in 52 (38.2%), IV in 61 (44.9%) and V in 22 (16.2%). Dimercapto-succinic acid scan revealed renal functional abnormalities in 63 children (51.2%). Vesicoureteral reflux resolved after the first endoscopic injection of dextranomer/hyaluronic acid in 93 ureters (68.4%), after a second injection in 35 (25.7%) and after a third injection in 8 (5.9%). Febrile urinary tract infection developed in 5 patients (4.1%) during followup. No patient required ureteral reimplantation or experienced significant complications. Our results confirm the safety and efficacy of endoscopic injection of dextranomer/hyaluronic acid in eradicating intermediate and high grade vesicoureteral reflux in patients with complete duplex systems. We recommend this minimally invasive, 15-minute outpatient procedure as a viable option for treating intermediate and high grade vesicoureteral reflux in patients with complete duplex collecting systems

  3. Phosphors for X-ray intensification screens

    International Nuclear Information System (INIS)

    Rebatin, J.G.

    1980-01-01

    An improved rare earth oxyhalide phosphor for x-ray intensification screens is described. The phosphors, of formula LnOX.T where Ln = La or Gd, X = Cl or Br and T = Tm or Tb, are mixed with a small amount of a trivalent antimony compound. The addition of antimony overcomes ageing due to attack by atmospheric moisture and renders the phosphor freeflowing so that dispersions can be readily made. Preferably the phosphor is washed with an aqueous solution of the antimony compound and the compound is the fluoride, chloride or butoxide, or potassium antimony tartrate. (U.K.)

  4. The sealing of second mandibular temporary molar pits and fissure with the laser of Nd: YAG, phosphoric acid and the glass ionomer cement; Selamento de fossulas e fissura de segundo molar deciduo inferior com laser de Nd: YAG, acido fosforico e cimento de ionomero de vidro

    Energy Technology Data Exchange (ETDEWEB)

    Toda, Maria Aparecida

    2003-07-01

    The main of our study was to check the sealing of second mandibular temporary molar pits and fissure, in vitro, with the laser of Nd: YAG, phosphoric acid at 37% and the glass ionomer cement (CIV, Fuji IX GC).The proposal was to check the structural morphologic changes in the laser irradiation upon the enamel surface to watch the pits and fissure sealing with the glass ionomer cement use after the laser irradiation and to verify the efficiency of the 'double conditioning' (phosphoric acid + Nd: YAG). At the same time we watch the evolution of the temperature in the pulp chamber's inside. Our desire was to achieve a therapeutic alternative technic to prevent the dental caries. The Nd: YAG laser parameters were the same: 79 mJ of energy per pulse; frequency of 5 Hz; mean power of 0,4 W; optical fiber on contact of 320 {mu}m diameter; fluency of 99,52 J/ cm{sup 2}, assuming that the only differential was the time of the laser application on the enamel surface. The samples were prepared with this way: Laser Nd: YAG (53 second) + acid + CIV (Fuji IX); Laser Nd: YAG (53 s); Laser Nd: YAG (20 s + 20 s) + acid + CIV; Laser Nd: YAG (20 s + 20 s); Acid + CIV; Control. Through the scanning electron microscopy (MEV) we noticed fusion and resolidification regions due to the laser irradiation and a better adaptation of the glass ionomer cement when we did the 'double conditioning'. Concerning the temperature increase we can conclude that the echeloned period was the best recommended because the temperature was found in a pattern that would not cause any damage to the dental pulp. For future studies we suggest a longer relaxing time between the laser irradiation, a comparative study of this method with other lasers, the use of other sealing materials and the study with the permanent teeth. (author)

  5. Enhancement of gold grade through arsenic removal in the gold concentrate using sulfuric acid baking and hot water leaching

    Science.gov (United States)

    On, Hyun-sung; Lim, Dae-hack; Myung, Eun-ji; Kim, Hyun-soo; Park, Cheon-young

    2017-04-01

    In order to improve gold recovery, in general, the roasting process is carried out on gold concentrate. However in this process, Arsenic(As) is released from the gold concentrate and valuable elements such as Fe, Cu, Zn and Pb are converted into oxides. This causes air pollution through the release of As and loss of valuable elements by discarding the oxide minerals in the tailings. In order to prevent the release of As and the loss of valuable metals, an acid baking experiment was carried out on the gold concentrate with the addition of an H2SO4 solution. The baking effect, H2SO4 concentration effect and the effects of changing the baking time were examined using an electric furnace. In experimental results, soluble metal sulfates such as Rhomboclase and Mikasite were formed in the baked samples as seen through XRD analysis. In hot(70 degree Celsius) water leaching of the roast and baked samples, As the contents leached were 60 times more in the baked sample than the roast sample, and the Fe, Cu, Zn and Pb contents were 17, 10, 14, 13 times in the baked sample than in the roast sample, respectively. In the water leached solid-residues, the maximum gold grade was upgraded by 33% due to the acid baking effect. It is confirmed that acid baking with H2SO4 prevented As release into the air and the recovery of valuable metals through hot water leaching such as Fe, Cu, Zn and Pb which were formerly discarded in the tailings. Acknowledgment : This work was supported by the Energy and Resources Engineering Program Grant funded by the Ministry of Trade, Industry and Energy, Korea

  6. Single center experience with endoscopic subureteral dextranomer/hyaluronic acid injection as first line treatment in 1,551 children with intermediate and high grade vesicoureteral reflux.

    Science.gov (United States)

    Puri, Prem; Kutasy, Balazs; Colhoun, Eric; Hunziker, Manuela

    2012-10-01

    In recent years the endoscopic injection of dextranomer/hyaluronic acid has become an established alternative to long-term antibiotic prophylaxis and the surgical management of vesicoureteral reflux. We determined the safety and effectiveness of the endoscopic injection of dextranomer/hyaluronic acid as first line treatment for high grade vesicoureteral reflux. Between 2001 and 2010, 1,551 children (496 male, 1,055 female, median age 1.6 years) underwent endoscopic correction of intermediate and high grade vesicoureteral reflux using dextranomer/hyaluronic acid soon after the diagnosis of vesicoureteral reflux on initial voiding cystourethrogram. Vesicoureteral reflux was unilateral in 761 children and bilateral in 790. Renal scarring was detected in 369 (26.7%) of the 1,384 patients who underwent dimercapto-succinic acid imaging. Reflux grade in the 2,341 ureters was II in 98 (4.2%), III in 1,340 (57.3%), IV in 818 (34.9%) and V in 85 (3.6%). Followup ultrasound and voiding cystourethrogram were performed 3 months after the outpatient procedure, and renal ultrasound was performed annually thereafter. Patients were followed for 3 months to 10 years (median 5.6 years). Vesicoureteral reflux resolved after the first, second and third endoscopic injection of dextranomer/hyaluronic acid in 2,039 (87.1%), 264 (11.3%) and 38 (1.6%) ureters, respectively. Febrile urinary tract infections developed during followup in 69 (4.6%) patients. None of the patients in the series needed reimplantation of ureters or experienced any significant complications. Our results confirm the safety and efficacy of the endoscopic injection of dextranomer/hyaluronic acid in the eradication of high grade vesicoureteral reflux. We recommend this 15-minute outpatient procedure as the first line of treatment for high grade vesicoureteral reflux. Copyright © 2012 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  7. Chemical process for recovery of uranium values contained in phosphoric mineral lixivia

    International Nuclear Information System (INIS)

    Conceicao, E.L.H. da; Awwal, M.A.; Coelho, S. V.

    1980-01-01

    A recovery process of uranium values from phosporic mineral lixivia for obtaining uranio oxide concentrate adjusted to specifications of purity for its commercialization the process consists of the adjustment of electromotive force of lixiviem to suitable values for uranium extraction, extraction with organic solvent containing phosphoric acid ester and oxidant reextraction from this solvent with phosphoric acid solution, suggesting a new solvent extraction containing synergetic mixture of di-2-ethyl hexyl phosphoric acid and tri-octyl phosphine, leaching this solvent with water and re-extraction/precipitation with ammonium carbonate solution, resulting in the formation of uranyl tricarbonate and ammonium, that by drying and calcination gives the uranium oxide with purity degree for commercialization. (M.C.K.) [pt

  8. LED lamp incorporating remote phosphor with heat dissipation features

    Science.gov (United States)

    Tong, Tao; Letoquin, Ronan; Keller, Bernd; Tarsa, Eric

    2016-11-22

    An LED lamp or bulb is disclosed that comprises a light source, a heat sink structure and a remote planar phosphor carrier having at least one conversion material. The phosphor carrier can be remote to the light sources and mounted to the heat sink so that heat from the phosphor carrier spreads into the heat sink. The phosphor carrier can comprise a thermally conductive transparent material and a phosphor layer, with an LED based light source mounted to the heat sink such that light from the light source passes through the phosphor carrier. At least some of the LED light is converted by the phosphor carrier, with some lamp embodiments emitting a white light combination of LED and phosphor light. The phosphor arranged according to the present invention can operate at lower temperature to thereby operate at greater phosphor conversion efficiency and with reduced heat related damage to the phosphor.

  9. 5-aminolevulinic acid for quantitative seek-and-treat of high-grade dysplasia in Barrett's esophagus cellular models

    Science.gov (United States)

    Yeh, Shu-Chi Allison; Ling, Celine S. N.; Andrews, David W.; Patterson, Michael S.; Diamond, Kevin R.; Hayward, Joseph E.; Armstrong, David; Fang, Qiyin

    2015-02-01

    High-grade dysplasia (HGD) in Barrett's esophagus (BE) poses increased risk for developing esophageal adenocarcinoma. To date, early detection and treatment of HGD regions are still challenging due to the sampling error from tissue biopsy and relocation error during the treatment after histopathological analysis. In this study, CP-A (metaplasia) and CP-B (HGD) cell lines were used to investigate the "seek-and-treat" potential using 5-aminolevulinic acid-induced protoporphyrin IX (PpIX). The photodynamic therapy photosensitizer then provides both a phototoxic effect and additional image contrast for automatic detection and real-time laser treatment. Complementary to our studies on automatic classification, this work focused on characterizing subcellular irradiation and the potential phototoxicity on both metaplasia and HGD. The treatment results showed that the HGD cells are less viable than metaplastic cells due to more PpIX production at earlier times. Also, due to mitochondrial localization of PpIX, a better killing effect was achieved by involving mitochondria or whole cells compared with just nucleus irradiation in the detected region. With the additional toxicity given by PpIX and potential morphological/textural differences for pattern recognition, this cellular platform serves as a platform to further investigate real-time "seek-and-treat" strategies in three-dimensional models for improving early detection and treatment of BE.

  10. 18F-Fluorocholine PET/CT, Brain MRI, and 5-Aminolevulinic Acid for the Assessment of Tumor Resection in High-Grade Glioma.

    Science.gov (United States)

    García Vicente, Ana María; Jiménez Aragón, Fátima; Villena Martín, Maikal; Jiménez Londoño, German Andrés; Borrás Moreno, Jose María

    2017-06-01

    High-grade glioma is a very aggressive and infiltrative tumor in which complete resection is a chance for a better outcome. We present the case of a 57-year-old man with a brain lesion suggestive of high-grade glioma. Brain MRI and F-fluorocholine PET/CT were performed previously to plan the surgery. Surgery was microscope assisted after the administration of 5-aminolevulinic acid. Postsurgery brain MRI and PET were blind evaluated to the surgery results and reported as probably gross total resection.

  11. FREQUENCY CHARACTERISTICS OF MODERN LED PHOSPHOR MATERIALS

    Directory of Open Access Journals (Sweden)

    Maxim S. Fudin

    2014-11-01

    Full Text Available Frequency characteristics of modern LED phosphor materials have been considered for the purpose of assessing the prospects of phosphor-based LEDs in wireless communication data systems which use optical wavelengths. The measurements have been carried out on the dependence of the emission intensity of single LEDs and LED chip-on-board modules with phosphors based on yttrium-aluminum and lutetium-aluminum garnets (with or without addition of nitridebased phosphors as well as silicate-based phosphors, on the frequency of electric pulses exciting the emission. It was shown that from the point of view of data transmission rate, garnet-based phosphors (including systems with added nitride phosphors are more promising than silicate–based ones. Garnet-based materials can be used in optical communication data systems with bandwidth (without extra modulation applied up to 3 MHz with single–chip LEDs and up to 4.5 MHz with 9- chip LED chip-on-board modules. The results of the work indicate that a significant part of white LEDs used in general lighting systems can be even now used for data transfer, for example, in systems assisting positioning in closed spaces to facilitate people searching necessary rooms or objects

  12. Phosphorous-Containing Polymers for Regenerative Medicine

    Science.gov (United States)

    Watson, Brendan M.; Kasper, F. Kurtis; Mikos, Antonios G.

    2014-01-01

    Disease and injury have resulted in a large, unmet need for functional tissue replacements. Polymeric scaffolds can be used to deliver cells and bioactive signals to address this need for regenerating damaged tissue. Phosphorous-containing polymers have been implemented to improve and accelerate the formation of native tissue both by mimicking the native role of phosphorous groups in the body and by attachment of other bioactive molecules. This manuscript reviews the synthesis, properties, and performance of phosphorous-containing polymers that can be useful in regenerative medicine applications. PMID:24565855

  13. Remoção de chumbo(II em sistemas descontínuos por carvões ativados com ácido fosfórico e com vapor Lead(II removal in discontinous systems by carbon activated by phosphoric acid and vapor

    Directory of Open Access Journals (Sweden)

    Cristiane Imenes de Campos Bueno

    2007-01-01

    Full Text Available Adsorption of heavy metal cations by activated carbon is dependent on the capacity of the material in promoting adsorption and the time needed to reach equilibrium. Carbon samples were previously activated either by phosphoric acid treatment at 400 ºC or by steam at 800 ºC. The results of Pb(II adsorption by these activated carbons have shown that equilibrium was typically reached within the first 5 min of contact between carbon and metal solution, with a maximum adsorption capacity higher than 69 mg g-1 for the vapor-activated sample. Temperature influences the sorption capacity, which corresponds to an endothermic process. Lead(II retention is more pronounced at high temperature and low pH.

  14. Phosphate Phosphors for Solid-State Lighting

    CERN Document Server

    Shinde, Kartik N; Swart, H C; Park, Kyeongsoon

    2012-01-01

    The idea for this book arose out of the realization that, although excellent surveys and a phosphor handbook are available, there is no single source covering the area of phosphate based phosphors especially for lamp industry. Moreover, as this field gets only limited attention in most general books on luminescence, there is a clear need for a book in which attention is specifically directed toward this rapidly growing field of solid state lighting and its many applications. This book is aimed at providing a sound introduction to the synthesis and optical characterization of phosphate phosphor for undergraduate and graduate students as well as teachers and researchers. The book provides guidance through the multidisciplinary field of solid state lighting specially phosphate phosphors for beginners, scientists and engineers from universities, research organizations, and especially industry. In order to make it useful for a wide audience, both fundamentals and applications are discussed, together.

  15. White LED phosphors: the next step

    Science.gov (United States)

    Yamamoto, Hajime

    2010-02-01

    Application of white LEDs is extended toward high-output light sources, e.g. for automotive headlights, and better spectral matching with optical filters for LCD backlighting. To meet such new demands, phosphor materials have been investigated with focus on their luminescence spectra, temperature characteristics and reliability. The conventional yellow phosphor based on Y3Al5O12:Ce3+ has excellent performance as a single phosphor combined with a blue LED. More recently developed nitrido- or oxonitrido-silicates activated with Eu2+ are also promising materials showing green to red luminescence depending on a composition and high thermal and chemical stability. And yet, demands for specific application have been made clear and strong. This paper reviews the present status and challenging goals of phosphors in the next stage further to make progress in white LEDs.

  16. Fluorimetrich determination of uranium in mineral samples and phosphoric solutions

    International Nuclear Information System (INIS)

    Pupo Gonzales, I.; Cuevillas, J.; Estevez, J.

    1991-01-01

    In this paper an analytical technique for the determination of uranium in different cuban minerals and acid leaching liquors of phosphorites is proposed. The method used for solid samples includes their disolution and further dilution of the solution obtained. For liquid samples dilution is the only intermediate step used. A study of HNO3 concentration (pH) was made in fluorimetric measurements. The method was applied to the uranium analysis in two IAEA standard reference samples (phosphate base), in natural phosphorites and a synthetic one, in clays and phosphoric liquors. The results agree with those obtained by other methods

  17. Efficient Production Process for Food Grade Acetic Acid by Acetobacter aceti in Shake Flask and in Bioreactor Cultures

    OpenAIRE

    Awad, Hassan M.; Diaz, Richard; Malek, Roslinda A.; Othman, Nor Zalina; Aziz, Ramlan A.; El Enshasy, Hesham A.

    2012-01-01

    Acetic acid is one of the important weak acids which had long history in chemical industries. This weak organic acid has been widely used as one of the key intermediate for many chemical, detergent, wood and food industries. The production of this acid is mainly carried out using submerged fermentation system and the standard strain Acetobacter aceti. In the present work, six different media were chosen from the literatures and tested for acetic acid production. The highest acetic acid produc...

  18. Serous tubal intraepithelial carcinoma upregulates markers associated with high-grade serous carcinomas including Rsf-1 (HBXAP), cyclin E and fatty acid synthase.

    Science.gov (United States)

    Sehdev, Ann Smith; Kurman, Robert J; Kuhn, Elisabetta; Shih, Ie-Ming

    2010-06-01

    Serous tubal intraepithelial carcinoma (STIC) has been proposed as a precursor for many pelvic high-grade serous carcinomas. Our previous analysis of the ovarian cancer genome identified several genes with oncogenic potential that are amplified and/or overexpressed in the majority of high-grade serous carcinomas. Determining whether these genes are upregulated in STICs is important in further elucidating the relationship of STICs to high-grade serous carcinomas and is fundamental in understanding the molecular pathogenesis of high-grade serous carcinomas. In this study, 37 morphologically defined STICs were obtained from 23 patients with stage IIIC/IV high-grade serous carcinomas. Both STICs and the high-grade serous carcinomas were analyzed for expression of Rsf-1 (HBXAP), cyclin E, fatty acid synthase (FASN) and mucin-4. In addition, they were examined for expression of established markers including p53, Ki-67 and p16. We found that diffuse nuclear p53 and p16 immunoreactivity was observed in 27 (75%) of 36 and 18 (55%) of 33 STICs, respectively, whereas an elevated Ki-67 labeling index (>or=10%) was detected in 29 (78%) of 37 STICs. Cyclin E nuclear staining was seen in 24 (77%) of 35 STICs, whereas normal tubal epithelial cells were all negative. Increased Rsf-1 and FASN immunoreactivity occurred in 63%, and 62% of STICs, respectively, compared with adjacent normal-appearing tubal epithelium. Interestingly, only one STIC showed increased mucin-4 immunoreactivity. Carcinomas, when compared with STICs, overexpressed p16, Rsf-1, cyclin E and FASN in a higher proportion of cases. In conclusion, STICs express several markers including Rsf-1, cyclin E and FASN in high-grade serous carcinomas. In contrast, mucin-4 immunoreactivity either did not change or was reduced in most STICs. These results suggest that overexpression of Rsf-1, cyclin E and FASN occurs early in tumor progression.

  19. Endoscopic treatment of grades IV and V vesicoureteral reflux with two bulking substances: Dextranomer hyaluronic acid copolymer versus polyacrylate polyalcohol copolymer in children.

    Science.gov (United States)

    Kocaoglu, Canan

    2016-10-01

    We aimed at evaluating the efficacy and complications of two bulking substances: dextranomer/hyaluronic acid copolymer(Dx/Ha;Dexell®) versus polyacrylate polyalcohol copolymer(PPC;Vantris®) in subureteric injection treatment of children with high grades (grades IV-V) vesicoureteral reflux(VUR). Data of patients undergoing endoscopic treatment of high grade VUR (January 2009-August 2015) were retrospectively investigated. Patients with high grade VUR caused by posterior urethral valve, duplex system, paraureteral diverticula and neurogenic bladder were excluded. Classical subureteric injection method (STING) was used. Seventy-three children (45 girls and 28 boys) who had 88 refluxing renal units (RRUs) with grades IV-V VUR (n=64/n=24) underwent endoscopic treatment using Dx/Ha (n=63 RRUs) and PPC (n=25 RRUs). Mean age of patients in Dx/Ha and PPC groups were 6 (3) and 6 (3.75) year (p=0.81), and volumes of these substances given were 1.3 (1) and 1 (0.5) mL (p=0.003), respectively. Overall, for the first endoscopic injection, success rate of grades IV-V VUR per RRU was 53.9% with Dx/Ha, compared to 80% in PPC-injected group, (p=0.024). Late ureterovesical junction obstruction developed only in one patient in PPC-injected group. No ureteral obstruction was observed in Dx/Ha-injected group. Endoscopic injection of PPC resulted in significantly higher success rate, compared to Dx/Ha in subureteric injection treatment of children with high grade VUR. However, the development of late ureterovesical junction obstruction should also be taken into account in PPC injection. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Molecular and supramolecular speciations of solvent extraction systems based on malonamide and/or dialkyl-phosphoric acids for An(III)/Ln(III); Speciations moleculaire et supramoleculaire de systemes d'extraction liquide-liquide a base de malonamide et/ou d'acides dialkylphosphoriques pour la separation An(III)/Ln(III)

    Energy Technology Data Exchange (ETDEWEB)

    Gannaz, B

    2006-06-15

    The solvent extraction system used in the DIAMEX-SANEX process, developed for the actinide(III)/lanthanide(III) separation, is based on the use of mixtures of the malonamide DMDOHEMA and a dialkyl-phosphoric acid (HDEHP or HDHP), in hydrogenated tetra-propylene. The complexity of these systems urges on a novel approach to improve the conventional methods (thermodynamics, solvent extraction) which hardly explain the macroscopic behaviors observed (3. phase, over-stoichiometry). This approach combines studies on both supramolecular (VPO, SANS, SAXS) and molecular (liquid-liquid extraction, ESI-MS, IR, EXAFS) speciations of single extractant systems (DMDOHEMA or HDHP in in n-dodecane) and their mixture. In spite of safety constraints due to the handling of radio-material, they were used in the studies as much as possible, like for SAXS measurements on americium-containing samples, a worldwide first-time. In each of the investigated systems, actinides(III) and lanthanides(III) are extracted to the organic phase in polar cores of reversed micelles, the inner and outer-sphere compositions of which are proposed. Thus, the 4f and 5f cations are extracted by reversed micelles such as [(DMDOHEMA){sub 2}M(NO{sub 3}){sub 3}]{sub inn} (DMDOHEMA){sub x}(HNO{sub 3}){sub z}(H{sub 2}O){sub w}]{sub out} and M(DHP){sub 3}(HDHP){sub y-3}(H{sub 2}O){sub w} with y = 3 to 6, for the single extractant systems. In the case of the two extractants system, the less concentrated one acts like a co-surfactant regarding the mixed aggregate formation [(DMDOHEMA){sub 2}M(NO{sub 3}){sub 3-v}(DHP){sub v}]{sub inn} [(DMDOFIEMA){sub x}(HDHP){sub y}(HNO{sub 3})z(H{sub 2}O){sub w}]{sub out}. (author)

  1. Fluorescent lighting with aluminum nitride phosphors

    Science.gov (United States)

    Cherepy, Nerine J.; Payne, Stephen A.; Seeley, Zachary M.; Srivastava, Alok M.

    2016-05-10

    A fluorescent lamp includes a glass envelope; at least two electrodes connected to the glass envelope; mercury vapor and an inert gas within the glass envelope; and a phosphor within the glass envelope, wherein the phosphor blend includes aluminum nitride. The phosphor may be a wurtzite (hexagonal) crystalline structure Al.sub.(1-x)M.sub.xN phosphor, where M may be drawn from beryllium, magnesium, calcium, strontium, barium, zinc, scandium, yttrium, lanthanum, cerium, praseodymium, europium, gadolinium, terbium, ytterbium, bismuth, manganese, silicon, germanium, tin, boron, or gallium is synthesized to include dopants to control its luminescence under ultraviolet excitation. The disclosed Al.sub.(1-x)M.sub.xN:Mn phosphor provides bright orange-red emission, comparable in efficiency and spectrum to that of the standard orange-red phosphor used in fluorescent lighting, Y.sub.2O.sub.3:Eu. Furthermore, it offers excellent lumen maintenance in a fluorescent lamp, and does not utilize "critical rare earths," minimizing sensitivity to fluctuating market prices for the rare earth elements.

  2. Comparison analysis on the properties of the phosphor film according to the various composition ratio of phosphor slurry

    Science.gov (United States)

    Park, Jeong Yeon; Lee, Jeong Won; Heo, Young Moo; Won, Si Tae; Yoon, Gil Sang

    2016-03-01

    The conventional method of making a phosphor layer on the LED package by using a dispensing method is difficult to implement the specific color coordinate, color temperature and optical efficiency because the thickness of the phosphor layer is non-uniform due to precipitation of the phosphor. Besides, the dispensing method consume a large amount of phosphor and silicone to fill the LED package. Thus, studies that manufacture phosphor layer with a uniform thickness such as spray coating, screen printing, electrophoresis are active recently. The purpose of this study is to perform the basic research about the change of the characteristics of phosphor film that is molded with uniform thickness using the phosphor slurry according to various silicone resin and phosphor composition ratio. It is expected to be used as useful information for the fabricating properties when production environment of phosphor layer is changed dispensing method into phosphor film fabrication. In the experiment, it was selected three kinds of methyl-phenyl silicone based resin as the phosphor slurry constituents, and mixed with phosphor various amount of 20 ˜ 60wt% content per one silicone resin. Using this mixed phosphor slurry, it was molded the phosphor film with 300 μm thickness and analyzed the mechanical properties and optical properties of the phosphor film. Finally, the results of this study are presented below: (a) As the phenyl group content is increased, the total heat of reaction need to cure the silicone resin is decrease, and also lower the durometer hardness of the phosphor sheet. On the other hand, it was confirmed that there is no relationship between the phenyl group content in the phosphor film and optical characteristics of the phosphor film. (b) If the amount of the phosphor within the film are increased, then the values of shore hardness and CIE color coordinates are increased gradually but the value of CIE color temperature is decreased gradually in case of being

  3. Extracting phosphorous from incinerated sewage sludge ash rich in iron or aluminum

    DEFF Research Database (Denmark)

    Ottosen, Lisbeth M.; Kirkelund, Gunvor M.; Jensen, Pernille E.

    2013-01-01

    Ashes from mono-incineration of sewage sludge (ISSA) generally contain high concentrations of phosphorous (P) and can be regarded as secondary P resources. ISSA has no direct value as fertilizer as P is not plant available. The present paper experimentally compares P extraction in acid from two d...

  4. MULTI-PHOTON PHOSPHOR FEASIBILITY RESEARCH

    Energy Technology Data Exchange (ETDEWEB)

    R. Graham; W. Chow

    2003-05-01

    Development of multi-photon phosphor materials for discharge lamps represents a goal that would achieve up to a doubling of discharge (fluorescent) lamp efficacy. This report reviews the existing literature on multi-photon phosphors, identifies obstacles in developing such phosphors, and recommends directions for future research to address these obstacles. To critically examine issues involved in developing a multi-photon phosphor, the project brought together a team of experts from universities, national laboratories, and an industrial lamp manufacturer. Results and findings are organized into three categories: (1) Multi-Photon Systems and Processes, (2) Chemistry and Materials Issues, and (3) Concepts and Models. Multi-Photon Systems and Processes: This category focuses on how to use our current understanding of multi-photon phosphor systems to design new phosphor systems for application in fluorescent lamps. The quickest way to develop multi-photon lamp phosphors lies in finding sensitizer ions for Gd{sup 3+} and identifying activator ions to red shift the blue emission from Pr{sup 3+} due to the {sup 1}S{sub 0} {yields} {sup 1}I{sub 6} transition associated with the first cascading step. Success in either of these developments would lead to more efficient fluorescent lamps. Chemistry and Materials Issues: The most promising multi-photon phosphors are found in fluoride hosts. However, stability of fluorides in environments typically found in fluorescent lamps needs to be greatly improved. Experimental investigation of fluorides in actual lamp environments needs to be undertaken while working on oxide and oxyfluoride alternative systems for backup. Concepts and Models: Successful design of a multi-photon phosphor system based on cascading transitions of Gd{sup 3+} and Pr{sup 3+} depends critically on how the former can be sensitized and the latter can sensitize an activator ion. Methods to predict energy level diagrams and Judd-Ofelt parameters of multi

  5. Hepatobiliary phase images using gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid-enhanced MRI as an imaging surrogate for the albumin–bilirubin grading system

    Energy Technology Data Exchange (ETDEWEB)

    Takatsu, Yasuo, E-mail: pcblue2@yahoo.co.jp [Department of Radiology, Osaka Red Cross Hospital, 5-30 Fudegasaki, Tennouji-ku, Osaka, 543-8555 (Japan); Division of Health Sciences, Graduate School of Medical Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, 920-0942 (Japan); Kobayashi, Satoshi, E-mail: satoshik@staff.kanazawa-u.ac.jp [Division of Health Sciences, Graduate School of Medical Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, 920-0942 (Japan); Miyati, Tosiaki, E-mail: ramiyati@mhs.mp.kanazawa-u.ac.jp [Division of Health Sciences, Graduate School of Medical Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, 920-0942 (Japan); Shiozaki, Toshiki, E-mail: shiozaki.toshiki@gmail.com [Department of Radiology, Osaka Red Cross Hospital, 5-30 Fudegasaki, Tennouji-ku, Osaka, 543-8555 (Japan)

    2016-12-15

    Objectives: To clarify the correlation between hepatobiliary phase (HBP) images using gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid (Gd-EOB-DTPA) and albumin–bilirubin (ALBI) grading system. Materials and methods: We evaluated 220 consecutive patients who underwent liver magnetic resonance imaging with Gd-EOB-DTPA. Quantitative liver–spleen contrast ratio (Q-LSC) was calculated in HBP images approximately 20 min after Gd-EOB-DTPA administration. To evaluate the degree of association between Q-LSC and ALBI grade, the Child–Pugh (C-P) score was used for comparison. Correlation coefficients were calculated, and median Q-LSC values were compared with the C-P scores and ALBI grades. The Steel–Dwass multiple comparison test was used for statistical analysis. Results: The correlation coefficient between Q-LSC and C-P score was −0.35, P < 0.0001, and the ALBI grade was −0.61, P < 0.0001. Q-LSC of overall median, C-P A, B, and C were 1.94, 1.91, 1.96, and 1.33, respectively. The differences between C-P A and C-P B, C-P B and C-P C, and C-P A and C-P C were P = 0.999, 0.126, and 0.149, respectively. Q-LSC of the overall median, ALBI grade 1, 2, and 3 were 1.94, 2.12, 1.69, and 1.30, respectively. The differences between ALBI grades 1 and 2, 2 and 3, and 1 and 3 were P < 0.0001, P = 0.0466, and P = 0.0035, respectively. Q-LSC was better correlated and discriminated by ALBI grade than C-P score. Conclusion: A strong correlation was observed between Q-LSC of an HBP image with Gd-EOB-DTPA and ALBI grade; HBP imaging could be a surrogate for the ALBI grade.

  6. Clinical response to glycyrrhizinic acid in genital infection due to human papillomavirus and low-grade squamous intraepithelial lesion

    Directory of Open Access Journals (Sweden)

    Marcelino Hernandez Valencia

    2011-11-01

    Full Text Available Human papilloma virus (HPV can infect any of the mucosal areas of the body and cause cervical cancer. Until recently, no specific treatments were available for this condition; therefore, any damaged tissue had to be removed or destroyed, which may have presented obstetrical repercussions for some women. Recently, new drugs have been developed that have shown to be effective for the cure of HPV infection. Glycyrrhizinic acid (GA has shown fewer side effects and its systemic use makes it possible to reach difficultto- treat lesions. The purpose of this study was to evaluate the clinical outcome of GA to eliminate the epithelial lesion and HPV. We carried out a longitudinal, descriptive study that included women of reproductive age who were diagnosed with HPV associated with low-grade squamous intraepithelial lesion (LSIL. Subjects began treatment based on GA using two routes of administration - systemic (oral and topical (spray - with assessments every month to determine the clinical changes of the lesions through colposcopy and Papanicolaou (Pap smear. Simple statistics were used along with two-tailed Student’s t-test; P<0.05 was considered statistically significant before and after treatment. There were 70 eligible patients, of whom 62 fulfilled the inclusion criteria. Age of subjects was 27.8±9.5 years. At the time of the study, 100% of the patients had HPV infection, 40% were associated with LSIL, and only 16% used a barrier contraceptive (condom method. Resolution was achieved in all patients from 4 weeks of treatment initiation and improvement was achieved in the majority of patients at 12 weeks (74% (P<0.001. However, there was persistence of LSIL in 27.7% of patients and only one patient progressed to cervical intraepithelial neoplasia (CIN II. The use of GA proved to be effective in resolving clinical HPV lesions. For cervical lesions with epithelial changes (LSIL, treatment may be required for a longer period as with other drugs used

  7. Evaluation of food grade solvents for lipid extraction and impact of storage temperature on fatty acid composition of edible seaweeds Laminaria digitata (Phaeophyceae) and Palmaria palmata (Rhodophyta).

    Science.gov (United States)

    Schmid, Matthias; Guihéneuf, Freddy; Stengel, Dagmar B

    2016-10-01

    This study evaluated the impact of different food- and non-food grade extraction solvents on yield and fatty acid composition of the lipid extracts of two seaweed species (Palmaria palmata and Laminaria digitata). The application of chloroform/methanol and three different food grade solvents (ethanol, hexane, ethanol/hexane) revealed significant differences in both, extraction yield and fatty acid composition. The extraction efficiency, in terms of yields of total fatty acids (TFA), was in the order: chloroform/methanol>ethanol>hexane>ethanol/hexane for both species. Highest levels of polyunsaturated fatty acids (PUFA) were achieved by the extraction with ethanol. Additionally the effect of storage temperature on the stability of PUFA in ground and freeze-dried seaweed biomass was investigated. Seaweed samples were stored for a total duration of 22months at three different temperatures (-20°C, 4°C and 20°C). Levels of TFA and PUFA were only stable after storage at -20°C for the two seaweed species. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Commercial- and whitewashing-grade limestone as a heterogeneous catalyst for synthesis of fatty acid methyl esters from used frying oil (UFO)

    Energy Technology Data Exchange (ETDEWEB)

    Agrawal, Shweta; Singh, Bhaskar; Sharma, Yogesh C. [Banaras Hindu University, Department of Applied Chemistry, Institute of Technology, Varanasi (India); Frometa, Amado Enrique N. [Universidad Tecnologica de Izucar de Matamoros, Puebla (Mexico)

    2012-12-15

    Commercial-grade limestone used in whitewashing which is a low-cost material has been used as a catalyst for the synthesis of fatty acid methyl esters. The catalyst was characterized by differential thermal analysis/thermogravimetric analysis, X-ray diffraction, and Fourier transform infrared spectroscopy for the study of its physicochemical nature. The catalyst was calcined at 900 C for 2.5 h for the decomposition of calcium carbonate to calcium oxide. The catalyst was further activated by dissolving 1.5 wt% of catalyst in 30 ml methanol (7.5:1, methanol to used frying oil molar ratio) and stirred at 25 C for 1 h on a magnetic stirrer. The transesterification reaction was performed using calcium oxide as a catalyst and then with the ''activated calcium oxide.'' The conversion obtained was 94.4 % with calcium oxide and was found to be lower for the ''activated calcium oxide'' (i.e., 87.36 %). The conversion increased to 96.8 % on increasing the catalyst amount to 2.0 wt% in 5 h. A high yield (>95 %) of fatty acid methyl esters was observed when either calcium oxide or ''activated calcium oxide'' was taken as catalyst. The catalytic activity of calcium oxide obtained from low-grade limestone has been found to be comparable with the laboratory-grade CaO. (orig.)

  9. Phosphor blends for high-CRI fluorescent lamps

    Science.gov (United States)

    Setlur, Anant Achyut [Niskayuna, NY; Srivastava, Alok Mani [Niskayuna, NY; Comanzo, Holly Ann [Niskayuna, NY; Manivannan, Venkatesan [Clifton Park, NY; Beers, William Winder [Chesterland, OH; Toth, Katalin [Pomaz, HU; Balazs, Laszlo D [Budapest, HU

    2008-06-24

    A phosphor blend comprises at least two phosphors each selected from one of the groups of phosphors that absorb UV electromagnetic radiation and emit in a region of visible light. The phosphor blend can be applied to a discharge gas radiation source to produce light sources having high color rendering index. A phosphor blend is advantageously includes the phosphor (Tb,Y,LuLa,Gd).sub.x(Al,Ga).sub.yO.sub.12:Ce.sup.3+, wherein x is in the range from about 2.8 to and including 3 and y is in the range from about 4 to and including 5.

  10. Blue-green phosphor for fluorescent lighting applications

    Science.gov (United States)

    Srivastava, Alok; Comanzo, Holly; Manivannan, Venkatesan; Setlur, Anant Achyut

    2005-03-15

    A fluorescent lamp including a phosphor layer including Sr.sub.4 Al.sub.14 O.sub.25 :Eu.sup.2+ (SAE) and at least one of each of a red, green and blue emitting phosphor. The phosphor layer can optionally include an additional, deep red phosphor and a yellow emitting phosphor. The resulting lamp will exhibit a white light having a color rendering index of 90 or higher with a correlated color temperature of from 2500 to 10000 Kelvin. The use of SAE in phosphor blends of lamps results in high CRI light sources with increased stability and acceptable lumen maintenance over, the course of the lamp life.

  11. Utilization of Ion Chromatography and Statistics to Determine Important Acids in Chromium Plating and Electropolishing Solutions

    National Research Council Canada - National Science Library

    Sopok, Samuel

    1991-01-01

    Inadequate monitoring of sulfuric and chromic acids in chromium plating solutions and phosphoric and sulfluric acids in electropolishing solutions can cause serious problems for the chromium plating...

  12. Recovering Y and Eu from Waste Phosphors Using Chlorination Roasting—Water Leaching Process

    Directory of Open Access Journals (Sweden)

    Mingming Yu

    2016-10-01

    Full Text Available Recovering Y and Eu from waste phosphors using chlorination roasting followed by a water leaching process was investigated in this study. Firstly, by chlorination roasting and water leaching, Y and Eu elements present in waste phosphors were efficiently extracted into a leach solution. Secondly, the majority of the impurities in the solution can be removed by adjusting the pH to 4.5 using a Na2S and NH3·H2O solution. Thirdly, the rare earths can be precipitated afterwards by adding a H2C2O4 solution and adjusting the pH to 2.0. Then rare earth oxides (REOs can be obtained after calcining at 800 °C for 1 h. The characterization study of the waste phosphors and the rare earth oxide products was performed by XRD, XRF, and SEM-EDS analysis to determine the phase and morphological features. Influences of the factors, such as roasting temperatures and time, the addition of ammonium chloride on the roasting of waste phosphors, as well as the pH and the amount of oxalates on the precipitation of Y and Eu, were investigated. The maximum grade (99.84% of mixed rare earth oxides and recovery rate (87.35% of Y and Eu were obtained at the optimized conditions.

  13. 40 CFR 721.3135 - Phosphorous modified epoxy resin (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Phosphorous modified epoxy resin... Specific Chemical Substances § 721.3135 Phosphorous modified epoxy resin (generic). (a) Chemical substance... phosphorous modified epoxy resin (PMNs P-00-992 and P-01-471) is subject to reporting under this section for...

  14. Efficient Production Process for Food Grade Acetic Acid by Acetobacter aceti in Shake Flask and in Bioreactor Cultures

    Directory of Open Access Journals (Sweden)

    Hassan M. Awad

    2012-01-01

    Full Text Available Acetic acid is one of the important weak acids which had long history in chemical industries. This weak organic acid has been widely used as one of the key intermediate for many chemical, detergent, wood and food industries. The production of this acid is mainly carried out using submerged fermentation system and the standard strain Acetobacter aceti. In the present work, six different media were chosen from the literatures and tested for acetic acid production. The highest acetic acid production was produced in medium composed of glucose, yeast extract and peptone. The composition of this medium was optimized by changing the concentration of medium components. The optimized medium was composed of (g/L: glucose, 100; yeast extract, 12 and peptone 5 and yielded 53 g/L acetic acid in shake flask after 144 h fermentation. Further optimization in the production process was achieved by transferring the process to semi-industrial scale 16-L stirred tank bioreactor and cultivation under controlled pH condition. Under fully aerobic conditions, the production of acetic acid reached maximal concentration of about 76 g/L and 51 g/L for uncontrolled and controlled pH cultures, respectively.

  15. Heterogeneous acid-catalyzed biodiesel production from crude tall oil: a low-grade and less expensive feedstock

    CSIR Research Space (South Africa)

    Mkhize, NM

    2015-06-01

    Full Text Available The present study indicates that solid acid catalysis of crude tall oil (CTO) over a WO3/ZrO2 catalyst is effective in converting the CTO fatty acids components into biodiesel in high yield. Preparation of the catalyst by an impregnation method...

  16. Glutathione biosynthesis and activity of dependent enzymes in food grade lactic acid bacteria harboring multidomain bifunctional fusion gene (gshF).

    Science.gov (United States)

    Pophaly, Sarang Dilip; Poonam; Pophaly, Saurabh Dilip; Kapila, Suman; Nanda, Dhiraj Kumar; Tomar, Sudhir Kumar; Singh, Rameshwar

    2017-04-12

    To assess glutathione (GSH) biosynthesis ability and activity of dependent enzymes in food grade lactic acid bacteria and correlating with genomic information on glutathione system in LAB. Whole genome sequences of twenty-six food grade LAB were screened for presence/absence of set of genes involved in de novo glutathione system. Multiple strains of S. thermophilus (37), Lb. casei (37), Lb. rhamnosus (4), Lb. paracasei (8) Lb. plantarum (23) & Lb. fermentum (22) were screened for biochemical evidence of GSH system. Multiple sequence analysis of GshF sequences was carried out for comparing the genomic signatures between GSH producing and non-producing species. Streptococcus thermophilus was found to have de novo glutathione biosynthesis as well as import ability. Lactobacillus spp. were negative for GSH synthesis but could import it from the medium. All the species exhibited prolific glutathione reductase and peroxidase activity. Sequence analysis revealed absence of key amino acid residues as well as a truncated N-terminal region in lactobacilli. The study provides a comprehensive view on status of an important antioxidative system (the glutathione system) in LAB and is expected to serve as a primer for future work on mechanistic role of GSH in the group. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  17. Intravascular imaging with a storage phosphor detector

    Science.gov (United States)

    Shikhaliev, Polad M.; Petrek, Peter; Matthews, Kenneth L., II; Fritz, Shannon G.; Bujenovic, L. Steven; Xu, Tong

    2010-05-01

    The aim of this study is to develop and test an intravascular positron imaging system based on a storage phosphor detector for imaging and detecting vulnerable plaques of human coronary arteries. The radiotracer F18-FDG accumulates in vulnerable plaques with inflammation of the overlying cap. The vulnerable plaques can, therefore, be imaged by recording positrons emitted from F18-FDG with a detector inserted into the artery. A prototype intravascular detector was constructed based on storage phosphor. The detector uses a flexible storage phosphor tube with 55 mm length, 2 mm diameter and 0.28 mm wall thickness. The intravascular detector is guided into the vessel using x-ray fluoroscopy and the accumulated x-ray signal must be erased prior to positron imaging. For this purpose, a light diffuser, 0.9 mm in diameter and 55 mm in length, was inserted into the detector tube. The light diffuser was connected to a laser source through a 2 m long optical fiber. The diffuser redirected the 0.38 W laser light to the inner surface of the phosphor detector to erase it. A heart phantom with 300 cm3 volume and three coronary arteries with 3.2 mm diameter and with several plaques was constructed. FDG solution with 0.5 µCi cm-3 activity concentration was filled in the heart and coronary arteries. The detector was inserted in a coronary artery and the signal from the plaques and surrounding background activity was recorded for 2 min. Then the phosphor detector was extracted and read out using a storage phosphor reader. The light diffuser erased the signal resulting from fluoroscopic exposure to level below that encountered during positron imaging. Vulnerable plaques with area activities higher than 1.2 nCi mm-2 were visualized by the detector. This activity is a factor of 10-20 lower than that expected in human vulnerable plaques. The detector was able to image the internal surface of the coronary vessels with 50 mm length and 360° circumference. Spatial resolution was 0

  18. High Extraction Phosphors for Solid State Lighting

    Energy Technology Data Exchange (ETDEWEB)

    Summers, Chris [Phosphortech Corporation, Kennesaw, GA (United States); Menkara, Hisham [Phosphortech Corporation, Kennesaw, GA (United States); Wagner, Brent [Phosphortech Corporation, Kennesaw, GA (United States)

    2011-09-01

    We have developed high-index, high efficiency bulk luminescent materials and novel nano-sized phosphors for improved solid-state white LED lamps. These advances can potentially contribute to reducing the loss in luminous efficiencies due to scattering, re-absorption, and thermal quenching. The bulk and nanostructured luminescent materials investigated are index matched to GaN and have broad and size-tunable absorption bands, size and impurity tuned emission bands, size-driven elimination of scattering effects, and a separation between absorption and emission bands. These innovations were accomplished through the use of novel synthesis techniques suitable for high volume production for LED lamp applications. The program produced a full-color set of high quantum yield phosphors with high chemical stability. In the bulk phosphor study, the ZnSeS:Cu,Ag phosphor was optimized to achieve >91% efficiency using erbium (Er) and other activators as sensitizers. Detailed analysis of temperature quenching effects on a large number of ZnSeS:Cu,Ag,X and strontium- and calcium-thiogallate phosphors lead to a breakthrough in the understanding of the anti-quenching behavior and a physical bandgap model was developed of this phenomena. In a follow up to this study, optimized phosphor blends for high efficiency and color performance were developed and demonstrated a 2-component phosphor system with good white chromaticity, color temperature, and high color rendering. By extending the protocols of quantum dot synthesis, large nanocrystals, greater than 20 nm in diameter were synthesized and exhibited bulk-like behavior and blue light absorption. The optimization of ZnSe:Mn nanophosphors achieved ~85% QE The limitations of core-shell nanocrystal systems were addressed by investigating alternative deltadoped structures. To address the manufacturability of these systems, a one-pot manufacturing protocol was developed for ZnSe:Mn nanophosphors. To enhance the stability of these material

  19. Research and development of a phosphoric acid fuel cell power generation system. ; Research and development of a fuel cell power generation system used in an isolated island. Rinsangata nenryo denchi no sogoteki gijutsu kaihatsu. ; Ritoyo nenryo denchi hatsuden system no kenkyu kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    1994-02-01

    This paper reports the research and development work on a fuel cell system using phosphoric acid fuel cells to be used in an isolated island. The system researches have included discussions on a technology to link alternating current with a diesel engine generator, a technology for optimal operation with a diesel engine generator, measures against salt damage to the present system, and a methanol acquiring method. The elementary researches have conducted development of composite electrodes, a composite electrode cell technology, and a methanol reforming technology with high load followability. The trial fabrication and operational researches of the power plant have performed plant design, trial fabrication of the fuel cells and reforming devices, and investigative studies on promoting introduction of the present system. In the system researches, an inverter has been designed to suppress overall voltage harmonic distortion the inverter generates to below 2% to 3%. The element researches have realized mass production of 3600-cm[sup 2] class composite electrode substrates. A small methanol reformer experiment has been carried out to verify the reformer's load responsiveness. A life evaluation on the catalyst combusting catalyst has discovered no deterioration in the catalyst in a 1000-hour continuous operation. 8 figs., 4 tabs.

  20. Treated Seawater as a Magnesium Source for Phosphorous Recovery from Wastewater—A Feasibility and Cost Analysis

    Directory of Open Access Journals (Sweden)

    Cejna Anna Quist-Jensen

    2016-12-01

    Full Text Available Conventional resources of phosphorous are at high risk of depletion in the near future due to current practices of its exploitation, thus new and improved exploration methodologies need to be developed to ensure phosphorous security. Today, some treatment plants recover phosphorous from municipal wastewater as struvite (MgNH4PO4·6H2O. Magnesium is often added to the wastewater as MgCl2·6H2O to facilitate the phosphorous recovery. However, the use of magnesium increases the costs of the process and is not aligned with sustainable development, therefore, alternative magnesium sources have to be found. The current study analyzes the feasibility of integrated membrane processes for magnesium recovery from seawater for utilization in the phosphorous recovery process. The integrated membrane systems consist of nanofiltration (NF, membrane distillation (MD, and membrane crystallization (MCr. The lowest associated cost is found for standalone NF treatment. However, the additional treatment with MD and MCr produces fresh water and salts like NaCl or potentially other valuable minerals at the expense of low-grade heat.

  1. Treated Seawater as a Magnesium Source for Phosphorous Recovery from Wastewater—A Feasibility and Cost Analysis

    Science.gov (United States)

    Quist-Jensen, Cejna Anna; Koustrup Jørgensen, Mads; Christensen, Morten Lykkegaard

    2016-01-01

    Conventional resources of phosphorous are at high risk of depletion in the near future due to current practices of its exploitation, thus new and improved exploration methodologies need to be developed to ensure phosphorous security. Today, some treatment plants recover phosphorous from municipal wastewater as struvite (MgNH4PO4·6H2O). Magnesium is often added to the wastewater as MgCl2·6H2O to facilitate the phosphorous recovery. However, the use of magnesium increases the costs of the process and is not aligned with sustainable development, therefore, alternative magnesium sources have to be found. The current study analyzes the feasibility of integrated membrane processes for magnesium recovery from seawater for utilization in the phosphorous recovery process. The integrated membrane systems consist of nanofiltration (NF), membrane distillation (MD), and membrane crystallization (MCr). The lowest associated cost is found for standalone NF treatment. However, the additional treatment with MD and MCr produces fresh water and salts like NaCl or potentially other valuable minerals at the expense of low-grade heat. PMID:27983583

  2. Polarographic determination of indium and thallium iodides in phosphor tablets

    International Nuclear Information System (INIS)

    Babich, G.A.; Dzhurka, G.F.; Kozhushko, G.M.; Kravtsova, K.F.; Magda, V.I.

    1984-01-01

    The technique of polarographic determination of indium and thallium iodides in phosphor tablets without preliminary separation of elements was developed. Mercury-dropping electrode was used as an indicator, and saturated calomel electrode was used as an auxiliary electrode. A recording of reduction currents was performed in the potential interval from -0.25 up to 1.15 V at potential sweep speed of 200 mV/min. Optimum conditions of sample acidic decomposition and polarography were presented. A solution of ethylene diamine (0.5 M), of ammonia (0.25 M) and of potassium chloride (0.05 M) served as a background electrolyte. The suggested technique allows one to determine component contents in tablets with a satisfactory accuracy. A period of one tablet analysis constitutes 1.5 h

  3. A study on the kinetics of high-energy phosphates in myocardium by phosphorous nuclear magnetic resonance

    International Nuclear Information System (INIS)

    Kusuoka, Hideo; Tsuneoka, Yutaka; Inoue, Michitoshi; Abe, Hiroshi; Watari, Hiroshi.

    1982-01-01

    Effect of artificial blood, FC 43 (Perfluorochemicals) on the kinetics of high-energy phosphate in the myocardium was evaluated by 31 P-NMR which permits a continuous and non-invasive assessment of in vivo phosphorus compounds. Cardiac perfusion was carried out on a excised rat heart with a Krebs-Henseleit modified solution and FC 43 alternately. Under the normal condition, ischemic condition, and at second perfusion amounts of intramyocardial creatine phosphoric acid, ATP, and inorganic phosphorus were determined by 31 P-NMR. Coronary flow was simultaneously estimated. The ischemic state due to interruption of perfusion resulted in a decrease in creatine phosphoric acid, which was associated with an increase in inorganic phosphorus and intracellular acidosis. No change of ATP amount was observed under ischemic state. With resumption of perfusion, the levels of creatine phosphoric acid and inorganic phosphorus rapidly returned to the normal. In the group of FC 43, coronary flow was 2.68 ml/min/g of the heart weight, about 1/2 of that of the Krebs-Henseleit group (5.68 ml/min/g of the heart weight). In controls, there was no difference between the two groups concerning creatine phosphoric acid level and recovery of creatine phospohric acid level after ischemia. These results showed that FC 43 supplies sufficient oxygen, and has no effect on the kinetics of energy in the myocardium. (Ueda, J.)

  4. The Influence of Phosphor and Binder Chemistry on the Aging Characteristics of Remote Phosphor Products

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Lynn; Yaga, Robert; Lamvik, Michael; Mills, Karmann; Fletcher, B.

    2017-06-30

    The influence of phosphor and binder layer chemistries on the lumen maintenance and color stability of remote phosphor disks were examined using wet high-temperature operational lifetime testing (WHTOL). As part of the experimental matrix, two different correlated color temperature (CCT) values, 2700 K and 5000 K, were studied and each had a different binder chemistry. The 2700 K samples used a urethane binder whereas the 5000 K samples used an acrylate binder. Experimental conditions were chosen to enable study of the binder and phosphor chemistries and to minimize photo-oxidation of the polycarbonate substrate. Under the more severe WHTOL conditions of 85°C and 85% relative humidity (RH), absorption in the binder layer significantly reduced luminous flux and produced a blue color shift. The milder WHTOL conditions of 75°C and 75% RH, resulted in chemical changes in the binder layer that may alter its index of refraction. As a result, lumen maintenance remained high, but a slight yellow shift was found. The aging of remote phosphor products provides insights into the impact of materials on the performance of phosphors in an LED lighting system.

  5. Micro/nano phosphors for gamma, electron, fast and thermal neutron dosimetry: an overview

    International Nuclear Information System (INIS)

    Dhole, Sanjay D.

    2016-01-01

    In this talk an overview of the micro/nano phosphors, nuclear track in glass and Fricke dosimeter will be covered. Eu and Cu doped K 2 Ca 2 (SO 4 ) 3 by chemical co-precipitation, CaSO 4 :Dy (micro by acid re-crystallization method and Al 2 O 3 :C by Thermal Plasma reactor method were synthesized and their photoluminescence (PL), Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL) properties were characterized

  6. Phosphor for thermoluminescent type radiation dosimeter

    International Nuclear Information System (INIS)

    Nada, N.; Yamashita, T.

    1975-01-01

    This has the accumulation effect of radiation energy and is mainly used as the element for thermoluminescent type radiation dosimeters. It has as the principal constituent a phosphor consisting of calcium sulfate as the principal constituent and other impurity elements such as dysprosium, thulium and the like. It is more sensitive by the order of 1 to 2 or more figures than the conventional ones and is excellent in the retention of absorbed radiation energy. (U.S.)

  7. Ultraviolet dosimetry using thermoluminescent phosphors - an update

    International Nuclear Information System (INIS)

    Nagpal, J.S.

    1998-04-01

    Intrinsic response of various thermoluminescent (TL) materials such as CaSO 4 (Dy, Eu, Mn, Sm, Tb, or Tm), LiF (Mg, Cu, P), Mg 2 SiO 4 :Tb, CaF 2 :Dy, CaF 2 :Tb, ThO 2 :Tb and Al 2 O 3 (Si, Ti); cathodoluminescent phosphors Y 3 Al 5 O 12 :Ce, Y 3 Al 5 O 12 :Tb and Y(V,P)O 4 :Eu; and fluorescent lamp phosphors calcium halophosphate (Mn,Sb) and Ce Mg aluminate (Eu, Tb) to ultraviolet (UV) radiations has been studied. Intrinsic TL response of most of the phosphors is rate (radiant flux) dependent. For the first time, UV response of the materials is reported for a fixed total radiant energy (total UV dose), at a single radiant flux (260 μW.cm -2 ), for an appropriate comparison. A wide range of UV sensitivity is observed. Studies conducted using UV radiation from two unfiltered low pressure mercury lamps show significant differences in glow curves, as compared to those obtained with nearly monochromatic UV radiations. Photons of wavelength 365 nm induce bleaching of TL induced by 254 nm photons, in most of the materials. Sequential/tandem exposures to 254 nm and 365 nm photons have yielded new but alarming results in CaF 2 :Tb. Preferential induction and bleaching of specific TL glow peaks by 365 nm and 254 nm photons are interesting characteristics discovered in CaSO 4 :Eu. Photoluminescence studies of Tb 3+ and Eu 3+ activated phosphors have augmented the inferences drawn from the bleaching effects produced by 365 nm photons. Earlier work carried out on phototransferred thermoluminescence of CaSO 4 :Dy-teflon dosimeters, TLD-100, Mg 2 SiO 4 :Tb and Al 2 O 3 (Si,Ti) has also been reviewed. (author)

  8. Nanopore formation on the surface oxide of commercially pure titanium grade 4 using a pulsed anodization method in sulfuric acid.

    Science.gov (United States)

    Williamson, R S; Disegi, J; Griggs, J A; Roach, M D

    2013-10-01

    Titanium and its alloys form a thin amorphous protective surface oxide when exposed to an oxygen environment. The properties of this oxide layer are thought to be responsible for titanium and its alloys biocompatibility, chemical inertness, and corrosion resistance. Surface oxide crystallinity and pore size are regarded to be two of the more important properties in establishing successful osseointegration. Anodization is an electrochemical method of surface modification used for colorization marking and improved bioactivity on orthopedic and dental titanium implants. Research on titanium anodization using sulphuric acid has been reported in the literature as being primarily conducted in molarity levels 3 M and less using either galvanostatic or potentiostatic methods. A wide range of pore diameters ranging from a few nanometers up to 10 μm have been shown to form in sulfuric acid electrolytes using the potentiostatic and galvanostatic methods. Nano sized pores have been shown to be beneficial for bone cell attachment and proliferation. The purpose of the present research was to investigate oxide crystallinity and pore formation during titanium anodization using a pulsed DC waveform in a series of sulfuric acid electrolytes ranging from 0.5 to 12 M. Anodizing titanium in increasing sulfuric acid molarities showed a trend of increasing transformations of the amorphous natural forming oxide to the crystalline phases of anatase and rutile. The pulsed DC waveform was shown to produce pores with a size range from ≤0.01 to 1 μm(2). The pore size distributions produced may be beneficial for bone cell attachment and proliferation.

  9. Particular aspect of the behaviour of the uranyl ion in phosphoric medium; Aspect particulier du comportement de l'ion uranyle en milieu phosphorique

    Energy Technology Data Exchange (ETDEWEB)

    Sefiani, N.; Hlaibi, M.; Saib, N.; Azzi, M. [Faculte des Sciences Ain Chock, Lab. Interface Materiaux Environnement (LIME), Casablanca (Morocco)

    2007-07-01

    The uranium element is present at trace amounts in phosphate ores. During the production of phosphoric acid by wet way, most of the uranium passes in solution. In order to control its extraction, it is important to understand the behaviour of uranium in this phosphoric medium and to determine under which form it exists. The aim of this work is to study the speciation of the uranyl ion in a phosphoric acid medium. Preliminary tests of conductometry and viscosimetry have shown that the conductivity and the viscosity of the phosphoric medium evolve with the concentration of the uranyl ion. They have allowed to reveal a process of interaction between the metallic cation and the phosphoric acid molecule. Spectrophotometric tests based on the principle of indirect photometry detection have confirmed the interaction between this metallic cation and the phosphate specie. These tests have allowed too to determine the molar uranium/ phosphate ratio and the number of protons involved during this interaction. The influence of the acidity of the medium on the stability of the formed specie coming from the interaction between the uranyl ion and the phosphoric acid molecules has been studied too. Thus, has been established the complexation reaction corresponding to this interaction. In order to obtain more data on the possible interactions between the uranyl and phosphate species, investigations by {sup 31}P NMR and by Raman spectroscopy have been carried out. With these tests, it has been possible to confirm the results obtained by indirect photometry and to identify the nature and the structure of the uranyl complex in phosphoric acid medium. The comparison of these results with previous studies have allowed to propose a structure of the specie in solution. (O.M.)

  10. Selective extraction and recovery of rare earth metals from phosphor powders in waste fluorescent lamps using an ionic liquid system.

    Science.gov (United States)

    Yang, Fan; Kubota, Fukiko; Baba, Yuzo; Kamiya, Noriho; Goto, Masahiro

    2013-06-15

    The recycling of rare earth metals from phosphor powders in waste fluorescent lamps by solvent extraction using ionic liquids was studied. Acid leaching of rare earth metals from the waste phosphor powder was examined first. Yttrium (Y) and europium (Eu) dissolved readily in the acid solution; however, the leaching of other rare earth metals required substantial energy input. Ionization of target rare earth metals from the waste phosphor powders into the leach solution was critical for their successful recovery. As a high temperature was required for the complete leaching of all rare earth metals, ionic liquids, for which vapor pressure is negligible, were used as an alternative extracting phase to the conventional organic diluent. An extractant, N, N-dioctyldiglycol amic acid (DODGAA), which was recently developed, showed a high affinity for rare earth metal ions in liquid-liquid extraction although a conventional commercial phosphonic extractant did not. An effective recovery of the rare earth metals, Y, Eu, La and Ce, from the metal impurities, Fe, Al and Zn, was achieved from the acidic leach solution of phosphor powders using an ionic liquid containing DODGAA as novel extractant system. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Investigation of uranium (VI) extraction mechanisms from phosphoric and sulfuric media by {sup 31}P-NMR

    Energy Technology Data Exchange (ETDEWEB)

    Fries, B.; Marie, C.; Pacary, V.; Berthon, C.; Miguirditchian, M.; Charbonnel, M.C. [CEA, Centre de Marcoule, Nuclear Energy Divison, RadioChemistry and Processes Department - DRCP, F-30207 Bagnols-sur-Ceze (France); Mokhtari, H. [AREVA Mines, Process and Analysis Department - SEPA, F-87250 Bessines-sur-Gartempe (France)

    2016-07-01

    Phosphate rocks contain uranium (∼1000 ppm on average) and are considered as a secondary source for uranium production. Uranium extraction using DEHCNPB (butyl-1-[N,N-bis(2-ethylhexyl)carbamoyl]nonyl phosphonic acid, a bifunctional cationic extractant) has been studied to better understand mechanism differences depending on the original acidic solution (phosphoric or sulfuric). Solvent extraction batch experiments were carried out and the organic phases were probed using {sup 31}P-NMR. This technique enabled to demonstrate that phosphoric acid is poorly extracted by DEHCNPB ([H{sub 3}PO{sub 4}]{sub org} < 2 mM), using direct quantification in the organic phase by {sup 31}P-NMR spectra integration. Moreover, in the presence of uranium in the initial phosphoric acid solution, uranyl extraction by DEHCNPB competes with H{sub 3}PO{sub 4} extraction. Average stoichiometries of U(VI)-DEHCNPB complexes in organic phases were also determined using slope analysis on uranium distribution data. Uranium seems to be extracted from a phosphoric medium by two extractant molecules, whereas more than three DEHCNPB on average would be necessary to extract uranium from a sulfuric medium. Thus, uranium is extracted according to different mechanisms depending on the nature of the initial solution. (authors)

  12. Selective extraction and recovery of rare earth metals from phosphor powders in waste fluorescent lamps using an ionic liquid system

    International Nuclear Information System (INIS)

    Yang, Fan; Kubota, Fukiko; Baba, Yuzo; Kamiya, Noriho; Goto, Masahiro

    2013-01-01

    Highlights: • Recycling of rare earth metals from fluorescent lamps was conducted by ionic liquid-mediated extraction. • Acid leaching from a waste phosphor powder was carried out using sulfuric and nitric acids. • An ionic liquid was used as extracting solvent for the rare earth metals. • Selective extraction of rare earth metals from leach solutions was attained. •The extracting ionic liquid phase was recyclable in the recovery process. -- Abstract: The recycling of rare earth metals from phosphor powders in waste fluorescent lamps by solvent extraction using ionic liquids was studied. Acid leaching of rare earth metals from the waste phosphor powder was examined first. Yttrium (Y) and europium (Eu) dissolved readily in the acid solution; however, the leaching of other rare earth metals required substantial energy input. Ionization of target rare earth metals from the waste phosphor powders into the leach solution was critical for their successful recovery. As a high temperature was required for the complete leaching of all rare earth metals, ionic liquids, for which vapor pressure is negligible, were used as an alternative extracting phase to the conventional organic diluent. An extractant, N, N-dioctyldiglycol amic acid (DODGAA), which was recently developed, showed a high affinity for rare earth metal ions in liquid–liquid extraction although a conventional commercial phosphonic extractant did not. An effective recovery of the rare earth metals, Y, Eu, La and Ce, from the metal impurities, Fe, Al and Zn, was achieved from the acidic leach solution of phosphor powders using an ionic liquid containing DODGAA as novel extractant system

  13. Synthesis of yellow emitting bis-pyrimidine based purely organic phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vinod, E-mail: vinod.phy@gmail.com [Department of Physics, University of the Free State, Bloemfontein, PO Box 9300 (South Africa); Gohain, Mukut [Department of Chemistry, University of the Free State, Bloemfontein, PO Box 9300 (South Africa); Kumar, Vijay [Department of Physics, University of the Free State, Bloemfontein, PO Box 9300 (South Africa); Van Tonder, Johannes H.; Bezuidenhoudt, Barend C.B. [Department of Chemistry, University of the Free State, Bloemfontein, PO Box 9300 (South Africa); Ntwaeaborwa, O.M. [Department of Physics, University of the Free State, Bloemfontein, PO Box 9300 (South Africa); Swart, Hendrik C., E-mail: swarthc@ufs.ac.za [Department of Physics, University of the Free State, Bloemfontein, PO Box 9300 (South Africa)

    2014-05-01

    Two organic phosphors 5,5'-(4-pyridinylmethylene)bis[1,3-dimethyl-2,4,6-(1H,3H,5H) -pyrimidinetrione] (BP) and 5,5'-(4-nitrophenylmethylene)bis[1,3-dimethyl-2,4,6-(1H,3H,5H) -pyrimidinetrione] (BP-NO{sub 2}) have been synthesized through a one pot reaction of N,N-dimethylbarbituric acid and pyridine aldehyde in acetonitrile at 80 °C. The synthesized phosphors were characterized by single-crystal X-ray crystallography, Fourier transform infrared spectroscopy, UV–vis spectroscopy, thermogravimetry analysis and photoluminescence (PL) spectroscopy. A broadband PL emission spectrum ranging from 400 to 800 nm was recorded from both phosphors. The BP showed a luminescence peak at ca. 560 nm (2.21 eV), while the BP-NO{sub 2} exhibited a peak at 590 nm (2.1 eV), which reflect pure yellow emissions. The optimized geometry of the phosphors has been studied with a quantum chemical approach using the density functional theory. The highest occupied and lowest unoccupied molecular orbitals are predicted from the calculations. - Highlights: • Two stable organic phosphors to bridge the yellow gap were synthesized. • PL emission spectrum ranging from 400 to 800 nm was recorded for both. • Luminescence peaks were obtained at 560 nm (2.21 eV) and 590 nm (2.1 eV). • The optimized geometry was obtained with a quantum chemical approach using DFT. • The HOMO and LUMO orbitals were predicted from the calculations.

  14. Phosphor Systems for Illumination Quality Solid State Lighting Products

    Energy Technology Data Exchange (ETDEWEB)

    Setlur, Anant; Briel, Linda; Cleaver, Robert; Clothier, Brent; Gao, Yan; Harlow, Richard; Henderson, Claire; Heward, William; Hill, M Christine; Lyons, Robert; Murphy, James; Siclovan, Oltea; Stoklosa, Stan; Happek, Uwe; Aanegola, Srinath; Aesram, Danny; Deshpande, Anirudha; Jacob, Cherian; Kolodin, Boris; Stoklosa, Emil; Beers, Williams

    2010-03-31

    The objective of this program is to develop phosphor systems that will enable LED lamps with 96 lm/W efficacy at correlated color temperatures, (CCTs) ~3000 K, and color rendering indices (CRIs) >80 and 71 lm/W efficacy at CCT<3100 K and CRI~95 using phosphor downconversion of LEDs. This primarily involves the invention and development of new phosphor materials that have improved efficiency and better match the eye sensitivity curves.

  15. Point defect engineering strategies to retard phosphorous diffusion in germanium.

    Science.gov (United States)

    Tahini, H A; Chroneos, A; Grimes, R W; Schwingenschlögl, U; Bracht, H

    2013-01-07

    The diffusion of phosphorous in germanium is very fast, requiring point defect engineering strategies to retard it in support of technological application. Density functional theory corroborated with hybrid density functional calculations are used to investigate the influence of the isovalent codopants tin and hafnium in the migration of phosphorous via the vacancy-mediated diffusion process. The migration energy barriers for phosphorous are increased significantly in the presence of oversized isovalent codopants. Therefore, it is proposed that tin and in particular hafnium codoping are efficient point defect engineering strategies to retard phosphorous migration.

  16. Challenging and development of phosphors for lighting applications

    Science.gov (United States)

    Panatarani, Camellia; Joni, I. Made

    2016-02-01

    Phosphors (inorganics luminescent material) have been extensively investigated due to their potential application especially for lighting. This article briefly reviews the developments of the phosphors for lighting application. Research and development of phosphors for the application of energy-saving lamps have been developed in the Laboratory of Instrumentation System and Functional Materials Processing, Department of Physics, Universitas Padjadjaran. To fulfill the desired feature for lighting application, we developed host-center type phosphor with compositional modifications prepared by spray pyrolysis and simple solution routes. In order to meet the industry requirement with high production rate, currently we scaled up the spray pyrolysis utilized with a pulse combustion reactor.

  17. Investigation of saturation effects in ceramic phosphors for laser lighting

    DEFF Research Database (Denmark)

    Krasnoshchoka, Anastasiia; Thorseth, Anders; Dam-Hansen, Carsten

    2017-01-01

    We report observation of saturation effects in a Ce:LuAG and Eu-doped nitride ceramic phosphor for conversion of blue laser light for white light generation. The luminous flux from the phosphors material increases linearly with the input power until saturation effects limit the conversion...... of the illumination. A phosphor conversion efficiency up to 140.8 lm/W with CRI of 89.4 was achieved. The saturation in a ceramic phosphor, when illuminated by high intensity laser diodes, is estimated to play the main role in limiting the available luminance from laser based lighting systems....

  18. Point defect engineering strategies to retard phosphorous diffusion in germanium

    KAUST Repository

    Tahini, H. A.

    2013-01-01

    The diffusion of phosphorous in germanium is very fast, requiring point defect engineering strategies to retard it in support of technological application. Density functional theory corroborated with hybrid density functional calculations are used to investigate the influence of the isovalent codopants tin and hafnium in the migration of phosphorous via the vacancy-mediated diffusion process. The migration energy barriers for phosphorous are increased significantly in the presence of oversized isovalent codopants. Therefore, it is proposed that tin and in particular hafnium codoping are efficient point defect engineering strategies to retard phosphorous migration. © the Owner Societies 2013.

  19. Overexpression of fatty acid synthase in human gliomas correlates with the WHO tumor grade and inhibition with Orlistat reduces cell viability and triggers apoptosis.

    Science.gov (United States)

    Grube, Susanne; Dünisch, Pedro; Freitag, Diana; Klausnitzer, Maren; Sakr, Yasser; Walter, Jan; Kalff, Rolf; Ewald, Christian

    2014-06-01

    Fatty acid synthase (FASN), catalyzing the de novo synthesis of fatty acids, is known to be deregulated in several cancers. Inhibition of this enzyme reduces tumor cell proliferation. Unfortunately, adverse effects and chemical instability prevent the in vivo use of the best-known inhibitors, Cerulenin and C75. Orlistat, a drug used for obesity treatment, is also considered as a potential FASN inhibitor, but its impact on glioma cell biology has not yet been described. In this study, we analyzed FASN expression in human glioma samples and primary glioblastoma cell cultures and the effects of FASN inhibition with Orlistat, Cerulenin and C75. Immunohistochemistry followed by densitometric analysis of 20 glioma samples revealed overexpression of FASN that correlated with the WHO tumor grade. Treatment of glioblastoma cells with these inhibitors resulted in a significant, dose-dependent reduction in tumor cell viability and fatty acid synthesis. Compared to Cerulenin and C75, Orlistat was a more potent inhibitor in cell cultures and cell lines. In LN229, cell-growth was reduced by 63.9 ± 8.7 % after 48 h and 200 µM Orlistat compared to controls; in LT68, the reduction in cell growth was 76.3 ± 23.7 %. Nuclear fragmentation assay and Western blotting analysis after targeting FASN with Orlistat demonstrated autophagy and apoptosis. Organotypic slice cultures treated with Orlistat showed reduced proliferation after Ki67 staining and increased caspase-3 cleavage. Our results suggest that FASN may be a therapeutic target in malignant gliomas and identify Orlistat as a possible anti-tumor drug in this setting.

  20. Rare earth activated phosphors for different applications

    International Nuclear Information System (INIS)

    Nazarov, Mihail

    2013-01-01

    For the purpose of development of highly energy-efficient light sources, one needs to design highly efficient green, red and yellow phosphors, which are able to absorb excitation energy and generate emissions. Using double activation, energy can be transferred from one luminescent activator to the other one, resulting in more efficient or brighter device operation. Co-activators can be added to a host material to change the color of the emitted light. The incorporation of Eu 3+ or Tb 3+ ions into the CaWO 4 crystal lattice modifies the luminescence spectrum due to the formation of the emission centers that generate the specific red and green light. Very efficient new red phosphors based on YnbO 4 and doped by Eu 3+ , Ga 3+ , Al 3+ allow recommend these materials as good candidates for different applications including LED and X-ray intensifying screens. For double activated TAG with Ce 3+ and Eu 3+ and for different mole ratio Ce/Eu the color temperature changes from 5500 K (0.331, 0.322) up to 4200 K (0.370, 0.381) and the light becomes 'warmer'. Application of TAG:Ce,Eu in the light emitting device shows the better chromaticity coordinates of luminescence and color rendering index of LEDs. Combination of Eu 2+ with Dy 3+ in SrAl 2 O 4 matrix allows us to create a material that emitted bright light for hours after ending the excitation. In this contribution we present our results on producing some efficient phosphors with improved luminescence properties for different applications: LED and X-ray intensifying screens, marine artificial reefs, biology and medicine. (authors)

  1. Phosphorous Doping of Nanostructured Crystalline Silicon

    DEFF Research Database (Denmark)

    Plakhotnyuk, Maksym; Davidsen, Rasmus Schmidt; Steckel, André

    surface aspect ration (22.25) of bSi to planar surface doping concentration might be slightly higher than on planar surfaces. Therefore, we conducted a study and present recent results of doping of bSi and compared their properties to planar Si. We doped planar, KOH-etched random pyramid and bSi surfaces...... with phosphorous (POCl3) in the temperature range 850-1000oC for 15 and 20 min, respectively. Sheet resistance measurements show slight differences in doping density between planar, KOH pyramidal and bSi structures. bSi samples have lower sheet resistance, pointing to higher doping density presumably due...

  2. Intra-articular Hyaluronic Acid (HA) and Platelet Rich Plasma (PRP) injection versus Hyaluronic acid (HA) injection alone in Patients with Grade III and IV Knee Osteoarthritis (OA): A Retrospective Study on Functional Outcome.

    Science.gov (United States)

    Saturveithan, C; Premganesh, G; Fakhrizzaki, S; Mahathir, M; Karuna, K; Rauf, K; William, H; Akmal, H; Sivapathasundaram, N; Jaspreet, K

    2016-07-01

    Introduction: Intra-articular hyaluronic acid (HA) is widely utilized in the treatment of knee osteoarthritis whereas platelet rich plasma (PRP) enhances the regeneration of articular cartilage. This study analyses the efficacy of HA and PRP in grade III and IV knee osteoarthritis. Methodology: This is a cross sectional study with retrospective review of 64 patients (101 knees) which includes 56 knees injected with HA+ PRP, and 45 knees with HA only. Results: During the post six months International Knee Documentation Committee (IKDC) evaluation, HA+PRP group showed marked improvement of 24.33 compared to 12.15 in HA group. Decrement in visual analogue score (VAS) in HA+PRP was 1.9 compared to 0.8 in HA group. Conclusion: We propose intra-articular HA and PRP injections as an optional treatment modality in Grade III and IV knee osteoarthritis in terms of functional outcome and pain control for up to six months when arthroplasty is not an option.

  3. Deactivation of vanadia-based commercial SCR catalysts by polyphosphoric acids

    DEFF Research Database (Denmark)

    Castellino, Francesco; Rasmussen, Søren Birk; Jensen, Anker Degn

    2008-01-01

    Commercial vanadia-based SCR monoliths have been exposed to flue gases in a pilot-scale Setup into which phosphoric acid has been added and the deactivation has been followed during the exposure time. Separate measurements by SMPS showed that the phosphoric acid formed polyphosphoric acid aerosols...

  4. Concentration and wavelength dependent frequency downshifting photoluminescence from a Tb3+ doped yttria nano-phosphor: A photochromic phosphor

    Science.gov (United States)

    Yadav, Ram Sagar; Rai, Shyam Bahadur

    2018-03-01

    In this article, the Tb3+ doped Y2O3 nano-phosphor has been synthesized through solution combustion method. The structural measurements of the nano-phosphor have been carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques, which reveal nano-crystalline nature. The Fourier transform infrared (FTIR) measurements reveal the presence of different molecular species in the nano-phosphor. The UV-Vis-NIR absorption spectrum of the nano-phosphor shows large number of bands due to charge transfer band (CTB) and 4f-4f electronic transitions of Tb3+ ion. The Tb3+ doped Y2O3 nano-phosphor emits intense green downshifting photoluminescence centered at 543 nm due to 5D4 → 7F5 transition on excitation with 350 nm. The emission intensity of the nano-phosphor is optimized at 1.0 mol% concentration of Tb3+ ion. When the as-synthesized nano-phosphor is annealed at higher temperature the emission intensity of the nano-phosphor enhances upto 5 times. The enhancement in the emission intensity is due to an increase in crystallinity of the nano-phosphor, reduction in surface defects and optical quenching centers. The CIE diagram reveals that the Tb3+ doped nano-phosphor samples show the photochromic nature (color tunability) with a change in the concentration of Tb3+ ion and excitation wavelength. The lifetime measurement indicates an increase in the lifetime for the annealed sample. Thus, the Tb3+ doped Y2O3 nano-phosphor may be used in photochromic displays and photonic devices.

  5. Luminescence spectroscopy of quantum cutting phosphors : materials, measurements and mechanisms

    NARCIS (Netherlands)

    Vergeer, Peter

    2005-01-01

    The industrial drive for this research is to find new phosphors for application in mercury-free fluorescent lamps and plasma display panels. The vacuum-ultraviolet (VUV) excitation light that is used in these devices allows for the use of phosphors that show emission of two photons for each photon

  6. Analysis of phosphoric ore bacterial and eucaryal microbial diversity ...

    African Journals Online (AJOL)

    These findings provided new opportunities into phosphoric ore microbiology that could be useful in biological system removing waste gases generated from the phosphoric industry. Keywords: Microbial community, bacteria, archaea, eucarya, mining residue. African Journal of Biotechnology, Vol 13(30) 3023-3029 ...

  7. Phosphor Scanner For Imaging X-Ray Diffraction

    Science.gov (United States)

    Carter, Daniel C.; Hecht, Diana L.; Witherow, William K.

    1992-01-01

    Improved optoelectronic scanning apparatus generates digitized image of x-ray image recorded in phosphor. Scanning fiber-optic probe supplies laser light stimulating luminescence in areas of phosphor exposed to x rays. Luminescence passes through probe and fiber to integrating sphere and photomultiplier. Sensitivity and resolution exceed previously available scanners. Intended for use in x-ray crystallography, medical radiography, and molecular biology.

  8. Study of the interaction metallic cation - ligand in concentrated phosphorus acid media; Etude de l'interaction cation metallique - ligand en milieu acide phosphorique concentre

    Energy Technology Data Exchange (ETDEWEB)

    Sefiani, N.; Azzi, M.; Hlaibi, M. [Faculte des Sciences Ain Chock, Laboratoire d' Electrochimie et Chimie de l' Environnement (LECE), Casablanca (Morocco); Kossair, A. [Centre de Recherche des Phosphates Mineraux (CERPHOS), Casablanca (Morocco)

    2005-07-01

    The phosphoric acid is more and more used with a high purity. The recovery of recycling element (uranium, vanadium, rare earth...) and the elimination of toxic element (cadmium, molybdenum, lead...) contained in the phosphoric acid are generally realized by extraction or precipitation. It is then very important to understand these impurities behavior in the phosphoric media in order to control their elimination. In this work, the authors considered the presence of some metallic cations (V, Al, fe, U) and fluorides ions as impurity in concentrated phosphoric acid media. (A.L.B.)

  9. Self-activating and doped tantalate phosphors.

    Energy Technology Data Exchange (ETDEWEB)

    Nyman, May Devan; Rohwer, Lauren Elizabeth Shea

    2011-01-01

    An ideal red phosphor for blue LEDs is one of the biggest challenges for the solid-state lighting industry. The appropriate phosphor material should have good adsorption and emission properties, good thermal and chemical stability, minimal thermal quenching, high quantum yield, and is preferably inexpensive and easy to fabricate. Tantalates possess many of these criteria, and lithium lanthanum tantalate materials warrant thorough investigation. In this study, we investigated red luminescence of two lithium lanthanum tantalates via three mechanisms: (1) Eu-doping, (2) Mn-doping and (3) self-activation of the tantalum polyhedra. Of these three mechanisms, Mn-doping proved to be the most promising. These materials exhibit two very broad adsorption peaks; one in the UV and one in the blue region of the spectrum; both can be exploited in LED applications. Furthermore, Mn-doping can be accomplished in two ways; ion-exchange and direct solid-state synthesis. One of the two lithium lanthanum tantalate phases investigated proved to be a superior host for Mn-luminescence, suggesting the crystal chemistry of the host lattice is important.

  10. UVC emitting phosphors obtained by spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Caiut, J.M.A., E-mail: jmacaiut@iq.unesp.b [Centre d' Elaboration de Materiaux et d' Etudes Structurales, CEMES/CNRS-BP 94347, 31055 Toulouse Cedex 4 (France); Institute of Chemistry, UNESP-Universidade Estadual Paulista, CP 355, Araraquara-SP 14801-970 (Brazil); Lechevallier, S.; Dexpert-Ghys, J. [Centre d' Elaboration de Materiaux et d' Etudes Structurales, CEMES/CNRS-BP 94347, 31055 Toulouse Cedex 4 (France); Caillier, B.; Guillot, Ph. [Diagnostic des Plasmas Hors Equilibre, Universite Jean Francois Champollion, place de Verdun, 81012 Albi Cedex 9 (France)

    2011-04-15

    The broadband inter-configurational (4f{sup 1}5d{sup 1{yields}}4f{sup 2}) emission of Pr{sup 3+} doped in lanthanum orthophosphate (LaPO{sub 4}) and in calcium pyrophosphate (Ca{sub 2}P{sub 2}O{sub 7}) has been investigated under plasma excitation. The synthesis by spray pyrolysis at moderate temperature followed by a controlled annealing proves to be a very efficient way to produce good quality UVC emitting phosphor Ca{sub 1.92}Pr{sub 0.04}Na{sub 0.04}P{sub 2}O{sub 7} ({alpha} phase). The emission of this phosphor in the wavelength range 200-350 nm has been measured with a prototype device, which can be employed for anti-microbial testing. - Research Highlights: {yields} The Pr{sup 3+} doped orthophosphate and pyrophosphate were synthesized by spray pyrolysis. {yields} The dense particles present good quality UVC emitting (200-350 nm). {yields} The prototype device can be employed for anti-microbial testing.

  11. Photoluminescence of phosphors for PDP with VUV excitation

    International Nuclear Information System (INIS)

    Lu, H.-C.; Chen, H.-K.; Tseng, T.-Y.; Kuo, W.-L.; Alam, M.S.; Cheng, B.-M.

    2005-01-01

    In a plasma display panel (PDP) He-Xe or Ne-Xe gaseous mixtures are subjected to electric discharge between two glass panels, so to generate VUV light. Red, green and blue phosphors absorb this VUV radiation and re-radiate the energy as visible light to produce the colors that appear on the screen. The phosphor plays an important role in the working of a PDP. To improve the efficiency of phosphors, we have established a photoluminescence end station coupled to the beam line of a synchrotron to study the luminescence of PDP phosphors. This luminescence is analyzed with a 0.32 m monochromator having maximum resolution 0.04 nm, and is monitored with a photomultiplier tube operated in a photon-counting mode. Preliminary data demonstrate the powerful performance of this end-station for studying PDP phosphors

  12. Thermal and Electrical Conductivity Measurements of CDA 510 Phosphor Bronze

    Science.gov (United States)

    Tuttle, James E.; Canavan, Edgar; DiPirro, Michael

    2009-01-01

    Many cryogenic systems use electrical cables containing phosphor bronze wire. While phosphor bronze's electrical and thermal conductivity values have been published, there is significant variation among different phosphor bronze formulations. The James Webb Space Telescope (JWST) will use several phosphor bronze wire harnesses containing a specific formulation (CDA 510, annealed temper). The heat conducted into the JWST instrument stage is dominated by these harnesses, and approximately half of the harness conductance is due to the phosphor bronze wires. Since the JWST radiators are expected to just keep the instruments at their operating temperature with limited cooling margin, it is important to know the thermal conductivity of the actual alloy being used. We describe an experiment which measured the electrical and thermal conductivity of this material between 4 and 295 Kelvin.

  13. Studies on Y{sub 2}SiO{sub 5}:Ce phosphors prepared by gel combustion using new fuels

    Energy Technology Data Exchange (ETDEWEB)

    Muresan, L.E., E-mail: laura_muresan2003@yahoo.com [“Raluca Ripan” Institute for Research in Chemistry, Babeş Bolyai University, Fântânele 30, 400294 Cluj-Napoca (Romania); Oprea, B.F.; Cadis, A.I.; Perhaita, I. [“Raluca Ripan” Institute for Research in Chemistry, Babeş Bolyai University, Fântânele 30, 400294 Cluj-Napoca (Romania); Ponta, O. [Faculty of Physics, Babeş Bolyai University, 400084 Cluj-Napoca (Romania)

    2014-12-05

    Highlights: • Y{sub 2}SiO{sub 5}:Ce was prepared by combustion using aspartic or glutamic acid as fuels. • Combustion process occurs differently depending on the fuels amount. • Single phase X2-Y{sub 2}SiO{sub 5} phosphors were obtained in fuel rich conditions. • PL measurements indicate that aspartic acid is a better fuel than glutamic. • Optimal preparative conditions were established for synthesis of Y{sub 2}SiO{sub 5}:Ce. - Abstract: Cerium activated yttrium silicate (Y{sub 2}SiO{sub 5}:Ce) phosphors were prepared by combustion, using yttrium–cerium nitrate as oxidizer, aspartic or glutamic acid as fuel and TEOS as source of silicon. In this study, aspartic and glutamic acid are used for the first time for the synthesis of Y{sub 2}SiO{sub 5}:Ce phosphors. The fuels molar amount was varied from 0.5 mol to 1.5 mol in order to reveal the thermal behavior of intermediary products (gels and ashes) same as the structural and luminescent characteristics of final products (phosphors). According to thermal analysis correlated with FTIR and XPS investigations, the combustion process occurs differently depending on the fuel amount; unreacted nitrate compounds have been identified in fuel lean conditions and carbonate based compounds along with organic residue in rich fuel conditions. The conversion to well crystallized silicates was revealed by changes of FTIR vibration bands and confirmed by XRD measurements. Based on luminescent spectra, aspartic acid is a better fuel than glutamic acid. A positive effect on the luminescence have been observed for samples fired in air due to complete remove of organic residue. The best luminescence was obtained for combustions with 0.75 mol aspartic acid and 1.25 mol glutamic respectively, fired at 1400 °C for 4 h in air atmosphere.

  14. Determination of Wastewater Acids from Chromium Plating and Electropolishing Solutions

    National Research Council Canada - National Science Library

    Sopok, Samuel

    1995-01-01

    ... Laboratories vessel plating program. The chemical literature provides offline laboratory detection of chromic acid from chromium plating wastewater solutions, as well as phosphoric and sulfuric acids from electropolishing wastewater solutions...

  15. Anthocyanins from purple sweet potato (Ipomoea batatas (L.) Lam.) and their color modulation by the addition of phenolic acids and food-grade phenolic plant extracts.

    Science.gov (United States)

    Gras, Claudia C; Nemetz, Nicole; Carle, Reinhold; Schweiggert, Ralf M

    2017-11-15

    Anthocyanin profiles and contents of three purple sweet potato provenances were investigated by HPLC-DAD-MS n . In contrast to widely uniform profiles, the contents of total (558-2477mg/100gDM) and individual anthocyanins varied widely. Furthermore, quantitative and qualitative effects of intermolecular co-pigmentation were studied by adding chlorogenic and rosmarinic acids, and food-grade phenolic apple and rosemary extracts at various dosages to a diluted purple sweet potato concentrate at pH 0.9, 2.6, 3.6, and 4.6. Addition of co-pigments generally increased pK H estimate -values of anthocyanins from 3.28 (without co-pigments) to up to 4.71, thus substantially broadening the pH range wherein colored forms prevail. The most pronounced hyperchromic shift by up to +50.5% at the absorption maximum was observed at pH 4.6. Simply by blending the co-pigments with purple sweet potato anthocyanins at pH-values ranging from 2.6 to 4.6, purplish-blue, light pink, magenta, brick-red, and intense red hues were accessible as expressed by CIE-L ∗ a ∗ b ∗ color values. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Acid-base properties and surface complexation modeling of phosphate anion adsorption by wasted low grade iron ore with high phosphorus.

    Science.gov (United States)

    Yuan, Xiaoli; Bai, Chenguang; Xia, Wentang; An, Juan

    2014-08-15

    The adsorption phenomena and specific reaction processes of phosphate onto wasted low grade iron ore with high phosphorus (WLGIOWHP) were studied in this work. Zeta potential and Fourier transform infrared spectroscopy (FTIR) analyses were used to elucidate the interaction mechanism between WLGIOWHP and aqueous solution. The results implied that the main adsorption mechanism was the replacement of surface hydroxyl groups by phosphate via the formation of inner-sphere complex. The adsorption process was characterized by chemical adsorption onto WLGIOWHP. The non-electrostatic model (NEM) was used to simulate the surface adsorption of phosphate onto WLGIOWHP. The total surface site density and protonation constants for NEM (N(T)=1.6×10(-4) mol/g, K(a1)=2.2×10(-4), K(a2)=6.82×10(-9)) were obtained by non-linear data fitting of acid-base titrations. In addition, the NEM was used to establish the surface adsorption complexation modeling of phosphate onto WLGIOWHP. The model successfully predicted the adsorption of phosphate onto WLGIOWHP from municipal wastewater. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. High color rendering index WLED based on YAG:Ce phosphor and CdS/ZnS core/shell quantum dots

    Science.gov (United States)

    Shen, Changyu; Li, Ke

    2009-08-01

    White LED combining of blue chip and YAG:Ce phosphor suffers from a red spectral deficiency, resulting in a relatively low value of color rendering index (CRI). In our study, for an effort to improve color rendering properties of YAG:Ce phosphor-based white LEDs, highly luminescent red-orange emitting CdS/ZnS QDs were blended with YAG:Ce phosphors. Core/shell CdS/ZnS quantum dots with the emission wavelength of 618nm, was synthesized by thermal deposition using cadmium oxide and selenium as precursors in a hot lauric acid and hexadecylamine trioctylphosphine oxide hybrid. YAG:Ce phosphor was synthesized by high-temperature solid state reaction at 900-1200°C in a slightly reducing atmosphere for 4 hours. Blends of phosphors and QDs exhibited the prominent spectral evolution with an increasing content of QDs. A hybrid white LED, which combines a blue LED with the blend of YAG phosphor and QDs with a weight ratio of 1.5:1,was demonstrated with an improved CRI value of 86.

  18. Study of the interaction metallic cation - ligand in concentrated phosphorus acid media

    International Nuclear Information System (INIS)

    Sefiani, N.; Azzi, M.; Hlaibi, M.; Kossair, A.

    2005-01-01

    The phosphoric acid is more and more used with a high purity. The recovery of recycling element (uranium, vanadium, rare earth...) and the elimination of toxic element (cadmium, molybdenum, lead...) contained in the phosphoric acid are generally realized by extraction or precipitation. It is then very important to understand these impurities behavior in the phosphoric media in order to control their elimination. In this work, the authors considered the presence of some metallic cations (V, Al, fe, U) and fluorides ions as impurity in concentrated phosphoric acid media. (A.L.B.)

  19. High Efficiency Colloidal Quantum Dot Phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Kahen, Keith

    2013-12-31

    The project showed that non-Cd containing, InP-based nanocrystals (semiconductor materials with dimensions of ~6 nm) have high potential for enabling next-generation, nanocrystal-based, on chip phosphors for solid state lighting. Typical nanocrystals fall short of the requirements for on chip phosphors due to their loss of quantum efficiency under the operating conditions of LEDs, such as, high temperature (up to 150 °C) and high optical flux (up to 200 W/cm2). The InP-based nanocrystals invented during this project maintain high quantum efficiency (>80%) in polymer-based films under these operating conditions for emission wavelengths ranging from ~530 to 620 nm. These nanocrystals also show other desirable attributes, such as, lack of blinking (a common problem with nanocrystals which limits their performance) and no increase in the emission spectral width from room to 150 °C (emitters with narrower spectral widths enable higher efficiency LEDs). Prior to these nanocrystals, no nanocrystal system (regardless of nanocrystal type) showed this collection of properties; in fact, other nanocrystal systems are typically limited to showing only one desirable trait (such as high temperature stability) but being deficient in other properties (such as high flux stability). The project showed that one can reproducibly obtain these properties by generating a novel compositional structure inside of the nanomaterials; in addition, the project formulated an initial theoretical framework linking the compositional structure to the list of high performance optical properties. Over the course of the project, the synthetic methodology for producing the novel composition was evolved to enable the synthesis of these nanomaterials at a cost approximately equal to that required for forming typical conventional nanocrystals. Given the above results, the last major remaining step prior to scale up of the nanomaterials is to limit the oxidation of these materials during the tens of

  20. Compact Regenerable Sulfur Scrubber for Phosphoric Acid Fuel Cells.

    Science.gov (United States)

    1987-11-30

    Giner, Inc. We would also like to thank Dr. Maria Flytzani- Stephanopoulos of the Massachusetts Institute of Technology for providing sorbent samples...commercially (United Catalysts G66B) or were provided by Dr. M. Stephanopoulos of the Massachusetts Institute of Technology (MIT). The sorbents obtained from...Dr. Stephanopoulos are in a highly dispersed, porous form prepared % by a gelation technique (3). The sources and compositions of all of the